6 @documentencoding UTF-8
7 @settitle GNU Guix Reference Manual
12 @c Identifier of the OpenPGP key used to sign tarballs and such.
13 @set OPENPGP-SIGNING-KEY-ID 090B11993D9AEBB5
16 Copyright @copyright{} 2012, 2013, 2014, 2015, 2016 Ludovic Courtès@*
17 Copyright @copyright{} 2013, 2014, 2016 Andreas Enge@*
18 Copyright @copyright{} 2013 Nikita Karetnikov@*
19 Copyright @copyright{} 2014, 2015, 2016 Alex Kost@*
20 Copyright @copyright{} 2015, 2016 Mathieu Lirzin@*
21 Copyright @copyright{} 2014 Pierre-Antoine Rault@*
22 Copyright @copyright{} 2015 Taylan Ulrich Bayırlı/Kammer@*
23 Copyright @copyright{} 2015, 2016 Leo Famulari@*
24 Copyright @copyright{} 2015, 2016 Ricardo Wurmus@*
25 Copyright @copyright{} 2016 Ben Woodcroft@*
26 Copyright @copyright{} 2016 Chris Marusich@*
27 Copyright @copyright{} 2016 Efraim Flashner@*
28 Copyright @copyright{} 2016 John Darrington@*
29 Copyright @copyright{} 2016 ng0
31 Permission is granted to copy, distribute and/or modify this document
32 under the terms of the GNU Free Documentation License, Version 1.3 or
33 any later version published by the Free Software Foundation; with no
34 Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A
35 copy of the license is included in the section entitled ``GNU Free
36 Documentation License''.
39 @dircategory System administration
41 * Guix: (guix). Manage installed software and system configuration.
42 * guix package: (guix)Invoking guix package. Installing, removing, and upgrading packages.
43 * guix build: (guix)Invoking guix build. Building packages.
44 * guix gc: (guix)Invoking guix gc. Reclaiming unused disk space.
45 * guix pull: (guix)Invoking guix pull. Update the list of available packages.
46 * guix system: (guix)Invoking guix system. Manage the operating system configuration.
49 @dircategory Software development
51 * guix environment: (guix)Invoking guix environment. Building development environments with Guix.
56 * Guix user interface: (guix)Emacs Interface. Package management from the comfort of Emacs.
61 @title GNU Guix Reference Manual
62 @subtitle Using the GNU Guix Functional Package Manager
63 @author The GNU Guix Developers
66 @vskip 0pt plus 1filll
67 Edition @value{EDITION} @*
75 @c *********************************************************************
79 This document describes GNU Guix version @value{VERSION}, a functional
80 package management tool written for the GNU system.
83 * Introduction:: What is Guix about?
84 * Installation:: Installing Guix.
85 * Package Management:: Package installation, upgrade, etc.
86 * Emacs Interface:: Using Guix from Emacs.
87 * Programming Interface:: Using Guix in Scheme.
88 * Utilities:: Package management commands.
89 * GNU Distribution:: Software for your friendly GNU system.
90 * Contributing:: Your help needed!
92 * Acknowledgments:: Thanks!
93 * GNU Free Documentation License:: The license of this manual.
94 * Concept Index:: Concepts.
95 * Programming Index:: Data types, functions, and variables.
98 --- The Detailed Node Listing ---
102 * Binary Installation:: Getting Guix running in no time!
103 * Requirements:: Software needed to build and run Guix.
104 * Running the Test Suite:: Testing Guix.
105 * Setting Up the Daemon:: Preparing the build daemon's environment.
106 * Invoking guix-daemon:: Running the build daemon.
107 * Application Setup:: Application-specific setup.
109 Setting Up the Daemon
111 * Build Environment Setup:: Preparing the isolated build environment.
112 * Daemon Offload Setup:: Offloading builds to remote machines.
116 * Features:: How Guix will make your life brighter.
117 * Invoking guix package:: Package installation, removal, etc.
118 * Substitutes:: Downloading pre-built binaries.
119 * Packages with Multiple Outputs:: Single source package, multiple outputs.
120 * Invoking guix gc:: Running the garbage collector.
121 * Invoking guix pull:: Fetching the latest Guix and distribution.
122 * Invoking guix archive:: Exporting and importing store files.
126 * Initial Setup: Emacs Initial Setup. Preparing @file{~/.emacs}.
127 * Package Management: Emacs Package Management. Managing packages and generations.
128 * Licenses: Emacs Licenses. Interface for licenses of Guix packages.
129 * Package Source Locations: Emacs Package Locations. Interface for package location files.
130 * Popup Interface: Emacs Popup Interface. Magit-like interface for guix commands.
131 * Prettify Mode: Emacs Prettify. Abbreviating @file{/gnu/store/@dots{}} file names.
132 * Build Log Mode: Emacs Build Log. Highlighting Guix build logs.
133 * Completions: Emacs Completions. Completing @command{guix} shell command.
134 * Development: Emacs Development. Tools for Guix developers.
135 * Hydra: Emacs Hydra. Interface for Guix build farm.
137 Programming Interface
139 * Defining Packages:: Defining new packages.
140 * Build Systems:: Specifying how packages are built.
141 * The Store:: Manipulating the package store.
142 * Derivations:: Low-level interface to package derivations.
143 * The Store Monad:: Purely functional interface to the store.
144 * G-Expressions:: Manipulating build expressions.
148 * package Reference:: The package data type.
149 * origin Reference:: The origin data type.
153 * Invoking guix build:: Building packages from the command line.
154 * Invoking guix edit:: Editing package definitions.
155 * Invoking guix download:: Downloading a file and printing its hash.
156 * Invoking guix hash:: Computing the cryptographic hash of a file.
157 * Invoking guix import:: Importing package definitions.
158 * Invoking guix refresh:: Updating package definitions.
159 * Invoking guix lint:: Finding errors in package definitions.
160 * Invoking guix size:: Profiling disk usage.
161 * Invoking guix graph:: Visualizing the graph of packages.
162 * Invoking guix environment:: Setting up development environments.
163 * Invoking guix publish:: Sharing substitutes.
164 * Invoking guix challenge:: Challenging substitute servers.
165 * Invoking guix container:: Process isolation.
167 Invoking @command{guix build}
169 * Common Build Options:: Build options for most commands.
170 * Package Transformation Options:: Creating variants of packages.
171 * Additional Build Options:: Options specific to 'guix build'.
175 * System Installation:: Installing the whole operating system.
176 * System Configuration:: Configuring the operating system.
177 * Installing Debugging Files:: Feeding the debugger.
178 * Security Updates:: Deploying security fixes quickly.
179 * Package Modules:: Packages from the programmer's viewpoint.
180 * Packaging Guidelines:: Growing the distribution.
181 * Bootstrapping:: GNU/Linux built from scratch.
182 * Porting:: Targeting another platform or kernel.
186 * Limitations:: What you can expect.
187 * Hardware Considerations:: Supported hardware.
188 * USB Stick Installation:: Preparing the installation medium.
189 * Preparing for Installation:: Networking, partitioning, etc.
190 * Proceeding with the Installation:: The real thing.
191 * Installing GuixSD in a VM:: GuixSD playground.
192 * Building the Installation Image:: How this comes to be.
196 * Using the Configuration System:: Customizing your GNU system.
197 * operating-system Reference:: Detail of operating-system declarations.
198 * File Systems:: Configuring file system mounts.
199 * Mapped Devices:: Block device extra processing.
200 * User Accounts:: Specifying user accounts.
201 * Locales:: Language and cultural convention settings.
202 * Services:: Specifying system services.
203 * Setuid Programs:: Programs running with root privileges.
204 * X.509 Certificates:: Authenticating HTTPS servers.
205 * Name Service Switch:: Configuring libc's name service switch.
206 * Initial RAM Disk:: Linux-Libre bootstrapping.
207 * GRUB Configuration:: Configuring the boot loader.
208 * Invoking guix system:: Instantiating a system configuration.
209 * Running GuixSD in a VM:: How to run GuixSD in a virtual machine.
210 * Defining Services:: Adding new service definitions.
214 * Base Services:: Essential system services.
215 * Scheduled Job Execution:: The mcron service.
216 * Networking Services:: Network setup, SSH daemon, etc.
217 * X Window:: Graphical display.
218 * Desktop Services:: D-Bus and desktop services.
219 * Database Services:: SQL databases.
220 * Mail Services:: IMAP, POP3, SMTP, and all that.
221 * Web Services:: Web servers.
222 * Various Services:: Other services.
226 * Service Composition:: The model for composing services.
227 * Service Types and Services:: Types and services.
228 * Service Reference:: API reference.
229 * Shepherd Services:: A particular type of service.
233 * Software Freedom:: What may go into the distribution.
234 * Package Naming:: What's in a name?
235 * Version Numbers:: When the name is not enough.
236 * Synopses and Descriptions:: Helping users find the right package.
237 * Python Modules:: Taming the snake.
238 * Perl Modules:: Little pearls.
239 * Java Packages:: Coffee break.
240 * Fonts:: Fond of fonts.
244 * Building from Git:: The latest and greatest.
245 * Running Guix Before It Is Installed:: Hacker tricks.
246 * The Perfect Setup:: The right tools.
247 * Coding Style:: Hygiene of the contributor.
248 * Submitting Patches:: Share your work.
252 * Programming Paradigm:: How to compose your elements.
253 * Modules:: Where to store your code?
254 * Data Types and Pattern Matching:: Implementing data structures.
255 * Formatting Code:: Writing conventions.
260 @c *********************************************************************
262 @chapter Introduction
265 GNU Guix@footnote{``Guix'' is pronounced like ``geeks'', or ``ɡiːks''
266 using the international phonetic alphabet (IPA).} is a package
267 management tool for the GNU system. Guix makes it easy for unprivileged
268 users to install, upgrade, or remove packages, to roll back to a
269 previous package set, to build packages from source, and generally
270 assists with the creation and maintenance of software environments.
272 @cindex user interfaces
273 Guix provides a command-line package management interface
274 (@pxref{Invoking guix package}), a set of command-line utilities
275 (@pxref{Utilities}), a visual user interface in Emacs (@pxref{Emacs
276 Interface}), as well as Scheme programming interfaces
277 (@pxref{Programming Interface}).
279 Its @dfn{build daemon} is responsible for building packages on behalf of
280 users (@pxref{Setting Up the Daemon}) and for downloading pre-built
281 binaries from authorized sources (@pxref{Substitutes}).
283 @cindex extensibility of the distribution
284 @cindex customization of packages
285 Guix includes package definitions for many GNU and non-GNU packages, all
286 of which @uref{https://www.gnu.org/philosophy/free-sw.html, respect the
287 user's computing freedom}. It is @emph{extensible}: users can write
288 their own package definitions (@pxref{Defining Packages}) and make them
289 available as independent package modules (@pxref{Package Modules}). It
290 is also @emph{customizable}: users can @emph{derive} specialized package
291 definitions from existing ones, including from the command line
292 (@pxref{Package Transformation Options}).
294 @cindex Guix System Distribution
296 You can install GNU@tie{}Guix on top of an existing GNU/Linux system
297 where it complements the available tools without interference
298 (@pxref{Installation}), or you can use it as part of the standalone
299 @dfn{Guix System Distribution} or GuixSD (@pxref{GNU Distribution}).
300 With GNU@tie{}GuixSD, you @emph{declare} all aspects of the operating
301 system configuration and Guix takes care of instantiating the
302 configuration in a transactional, reproducible, and stateless fashion
303 (@pxref{System Configuration}).
305 @cindex functional package management
306 Under the hood, Guix implements the @dfn{functional package management}
307 discipline pioneered by Nix (@pxref{Acknowledgments}).
308 In Guix, the package build and installation process is seen
309 as a @emph{function}, in the mathematical sense. That function takes inputs,
310 such as build scripts, a compiler, and libraries, and
311 returns an installed package. As a pure function, its result depends
312 solely on its inputs---for instance, it cannot refer to software or
313 scripts that were not explicitly passed as inputs. A build function
314 always produces the same result when passed a given set of inputs. It
315 cannot alter the environment of the running system in
316 any way; for instance, it cannot create, modify, or delete files outside
317 of its build and installation directories. This is achieved by running
318 build processes in isolated environments (or @dfn{containers}), where only their
319 explicit inputs are visible.
322 The result of package build functions is @dfn{cached} in the file
323 system, in a special directory called @dfn{the store} (@pxref{The
324 Store}). Each package is installed in a directory of its own in the
325 store---by default under @file{/gnu/store}. The directory name contains
326 a hash of all the inputs used to build that package; thus, changing an
327 input yields a different directory name.
329 This approach is the foundation for the salient features of Guix: support
330 for transactional package upgrade and rollback, per-user installation, and
331 garbage collection of packages (@pxref{Features}).
334 @c *********************************************************************
336 @chapter Installation
338 GNU Guix is available for download from its website at
339 @url{http://www.gnu.org/software/guix/}. This section describes the
340 software requirements of Guix, as well as how to install it and get
343 Note that this section is concerned with the installation of the package
344 manager, which can be done on top of a running GNU/Linux system. If,
345 instead, you want to install the complete GNU operating system,
346 @pxref{System Installation}.
348 @cindex foreign distro
349 When installed on a running GNU/Linux system---thereafter called a
350 @dfn{foreign distro}---GNU@tie{}Guix complements the available tools
351 without interference. Its data lives exclusively in two directories,
352 usually @file{/gnu/store} and @file{/var/guix}; other files on your
353 system, such as @file{/etc}, are left untouched.
356 * Binary Installation:: Getting Guix running in no time!
357 * Requirements:: Software needed to build and run Guix.
358 * Running the Test Suite:: Testing Guix.
359 * Setting Up the Daemon:: Preparing the build daemon's environment.
360 * Invoking guix-daemon:: Running the build daemon.
361 * Application Setup:: Application-specific setup.
364 @node Binary Installation
365 @section Binary Installation
367 This section describes how to install Guix on an arbitrary system from a
368 self-contained tarball providing binaries for Guix and for all its
369 dependencies. This is often quicker than installing from source, which
370 is described in the next sections. The only requirement is to have
373 Installing goes along these lines:
377 Download the binary tarball from
378 @indicateurl{ftp://alpha.gnu.org/gnu/guix/guix-binary-@value{VERSION}.@var{system}.tar.xz},
379 where @var{system} is @code{x86_64-linux} for an @code{x86_64} machine
380 already running the kernel Linux, and so on.
382 @c The following is somewhat duplicated in ``System Installation''.
383 Make sure to download the associated @file{.sig} file and to verify the
384 authenticity of the tarball against it, along these lines:
387 $ wget ftp://alpha.gnu.org/gnu/guix/guix-binary-@value{VERSION}.@var{system}.tar.xz.sig
388 $ gpg --verify guix-binary-@value{VERSION}.@var{system}.tar.xz.sig
391 If that command fails because you do not have the required public key,
392 then run this command to import it:
395 $ gpg --keyserver pgp.mit.edu --recv-keys @value{OPENPGP-SIGNING-KEY-ID}
399 and rerun the @code{gpg --verify} command.
400 @c end authentication part
407 # tar --warning=no-timestamp -xf \
408 guix-binary-@value{VERSION}.@var{system}.tar.xz
409 # mv var/guix /var/ && mv gnu /
412 This creates @file{/gnu/store} (@pxref{The Store}) and @file{/var/guix}.
413 The latter contains a ready-to-use profile for @code{root} (see next
416 Do @emph{not} unpack the tarball on a working Guix system since that
417 would overwrite its own essential files.
419 The @code{--warning=no-timestamp} option makes sure GNU@tie{}tar does
420 not emit warnings about ``implausibly old time stamps'' (such
421 warnings were triggered by GNU@tie{}tar 1.26 and older; recent
423 They stem from the fact that all the
424 files in the archive have their modification time set to zero (which
425 means January 1st, 1970.) This is done on purpose to make sure the
426 archive content is independent of its creation time, thus making it
430 Make @code{root}'s profile available under @file{~/.guix-profile}:
433 # ln -sf /var/guix/profiles/per-user/root/guix-profile \
438 Create the group and user accounts for build users as explained below
439 (@pxref{Build Environment Setup}).
442 Run the daemon, and set it to automatically start on boot.
444 If your host distro uses the systemd init system, this can be achieved
448 # cp ~root/.guix-profile/lib/systemd/system/guix-daemon.service \
450 # systemctl start guix-daemon && systemctl enable guix-daemon
453 If your host distro uses the Upstart init system:
456 # cp ~root/.guix-profile/lib/upstart/system/guix-daemon.conf /etc/init/
460 Otherwise, you can still start the daemon manually with:
463 # ~root/.guix-profile/bin/guix-daemon --build-users-group=guixbuild
467 Make the @command{guix} command available to other users on the machine,
471 # mkdir -p /usr/local/bin
473 # ln -s /var/guix/profiles/per-user/root/guix-profile/bin/guix
476 It is also a good idea to make the Info version of this manual available
480 # mkdir -p /usr/local/share/info
481 # cd /usr/local/share/info
482 # for i in /var/guix/profiles/per-user/root/guix-profile/share/info/* ;
486 That way, assuming @file{/usr/local/share/info} is in the search path,
487 running @command{info guix} will open this manual (@pxref{Other Info
488 Directories,,, texinfo, GNU Texinfo}, for more details on changing the
492 To use substitutes from @code{hydra.gnu.org} or one of its mirrors
493 (@pxref{Substitutes}), authorize them:
496 # guix archive --authorize < ~root/.guix-profile/share/guix/hydra.gnu.org.pub
500 This completes root-level install of Guix. Each user will need to
501 perform additional steps to make their Guix environment ready for use,
502 @pxref{Application Setup}.
504 You can confirm that Guix is working by installing a sample package into
508 # guix package -i hello
511 The @code{guix} package must remain available in @code{root}'s profile,
512 or it would become subject to garbage collection---in which case you
513 would find yourself badly handicapped by the lack of the @command{guix}
514 command. In other words, do not remove @code{guix} by running
515 @code{guix package -r guix}.
517 The binary installation tarball can be (re)produced and verified simply
518 by running the following command in the Guix source tree:
521 make guix-binary.@var{system}.tar.xz
526 @section Requirements
528 This section lists requirements when building Guix from source. The
529 build procedure for Guix is the same as for other GNU software, and is
530 not covered here. Please see the files @file{README} and @file{INSTALL}
531 in the Guix source tree for additional details.
533 GNU Guix depends on the following packages:
536 @item @url{http://gnu.org/software/guile/, GNU Guile}, version 2.0.7 or later;
537 @item @url{http://gnupg.org/, GNU libgcrypt};
538 @item @url{http://www.gnu.org/software/make/, GNU Make}.
541 The following dependencies are optional:
545 Installing @uref{http://gnutls.org/, GnuTLS-Guile} will allow you to
546 access @code{https} URLs for substitutes, which is highly recommended
547 (@pxref{Substitutes}). It also allows you to access HTTPS URLs with the
548 @command{guix download} command (@pxref{Invoking guix download}), the
549 @command{guix import pypi} command, and the @command{guix import cpan}
550 command. @xref{Guile Preparations, how to install the GnuTLS bindings
551 for Guile,, gnutls-guile, GnuTLS-Guile}.
555 @url{http://savannah.nongnu.org/projects/guile-json/, Guile-JSON} will
556 allow you to use the @command{guix import pypi} command (@pxref{Invoking
557 guix import}). It is of
558 interest primarily for developers and not for casual users.
561 When @url{http://zlib.net, zlib} is available, @command{guix publish}
562 can compress build byproducts (@pxref{Invoking guix publish}).
565 Unless @code{--disable-daemon} was passed to @command{configure}, the
566 following packages are also needed:
569 @item @url{http://sqlite.org, SQLite 3};
570 @item @url{http://www.bzip.org, libbz2};
571 @item @url{http://gcc.gnu.org, GCC's g++}, with support for the
575 When configuring Guix on a system that already has a Guix installation,
576 be sure to specify the same state directory as the existing installation
577 using the @code{--localstatedir} option of the @command{configure}
578 script (@pxref{Directory Variables, @code{localstatedir},, standards,
579 GNU Coding Standards}). The @command{configure} script protects against
580 unintended misconfiguration of @var{localstatedir} so you do not
581 inadvertently corrupt your store (@pxref{The Store}).
583 When a working installation of @url{http://nixos.org/nix/, the Nix package
584 manager} is available, you
585 can instead configure Guix with @code{--disable-daemon}. In that case,
586 Nix replaces the three dependencies above.
588 Guix is compatible with Nix, so it is possible to share the same store
589 between both. To do so, you must pass @command{configure} not only the
590 same @code{--with-store-dir} value, but also the same
591 @code{--localstatedir} value. The latter is essential because it
592 specifies where the database that stores metadata about the store is
593 located, among other things. The default values for Nix are
594 @code{--with-store-dir=/nix/store} and @code{--localstatedir=/nix/var}.
595 Note that @code{--disable-daemon} is not required if
596 your goal is to share the store with Nix.
598 @node Running the Test Suite
599 @section Running the Test Suite
601 After a successful @command{configure} and @code{make} run, it is a good
602 idea to run the test suite. It can help catch issues with the setup or
603 environment, or bugs in Guix itself---and really, reporting test
604 failures is a good way to help improve the software. To run the test
611 Test cases can run in parallel: you can use the @code{-j} option of
612 GNU@tie{}make to speed things up. The first run may take a few minutes
613 on a recent machine; subsequent runs will be faster because the store
614 that is created for test purposes will already have various things in
617 It is also possible to run a subset of the tests by defining the
618 @code{TESTS} makefile variable as in this example:
621 make check TESTS="tests/store.scm tests/cpio.scm"
624 By default, tests results are displayed at a file level. In order to
625 see the details of every individual test cases, it is possible to define
626 the @code{SCM_LOG_DRIVER_FLAGS} makefile variable as in this example:
629 make check TESTS="tests/base64.scm" SCM_LOG_DRIVER_FLAGS="--brief=no"
632 Upon failure, please email @email{bug-guix@@gnu.org} and attach the
633 @file{test-suite.log} file. Please specify the Guix version being used
634 as well as version numbers of the dependencies (@pxref{Requirements}) in
637 Guix also comes with a whole-system test suite that tests complete
638 GuixSD operating system instances. It can only run on systems where
639 Guix is already installed, using:
646 or, again, by defining @code{TESTS} to select a subset of tests to run:
649 make check-system TESTS="basic mcron"
652 These system tests are defined in the @code{(gnu tests @dots{})}
653 modules. They work by running the operating systems under test with
654 lightweight instrumentation in a virtual machine (VM). They can be
655 computationally intensive or rather cheap, depending on whether
656 substitutes are available for their dependencies (@pxref{Substitutes}).
657 Some of them require a lot of storage space to hold VM images.
659 Again in case of test failures, please send @email{bug-guix@@gnu.org}
662 @node Setting Up the Daemon
663 @section Setting Up the Daemon
666 Operations such as building a package or running the garbage collector
667 are all performed by a specialized process, the @dfn{build daemon}, on
668 behalf of clients. Only the daemon may access the store and its
669 associated database. Thus, any operation that manipulates the store
670 goes through the daemon. For instance, command-line tools such as
671 @command{guix package} and @command{guix build} communicate with the
672 daemon (@i{via} remote procedure calls) to instruct it what to do.
674 The following sections explain how to prepare the build daemon's
675 environment. See also @ref{Substitutes}, for information on how to allow
676 the daemon to download pre-built binaries.
679 * Build Environment Setup:: Preparing the isolated build environment.
680 * Daemon Offload Setup:: Offloading builds to remote machines.
683 @node Build Environment Setup
684 @subsection Build Environment Setup
686 In a standard multi-user setup, Guix and its daemon---the
687 @command{guix-daemon} program---are installed by the system
688 administrator; @file{/gnu/store} is owned by @code{root} and
689 @command{guix-daemon} runs as @code{root}. Unprivileged users may use
690 Guix tools to build packages or otherwise access the store, and the
691 daemon will do it on their behalf, ensuring that the store is kept in a
692 consistent state, and allowing built packages to be shared among users.
695 When @command{guix-daemon} runs as @code{root}, you may not want package
696 build processes themselves to run as @code{root} too, for obvious
697 security reasons. To avoid that, a special pool of @dfn{build users}
698 should be created for use by build processes started by the daemon.
699 These build users need not have a shell and a home directory: they will
700 just be used when the daemon drops @code{root} privileges in build
701 processes. Having several such users allows the daemon to launch
702 distinct build processes under separate UIDs, which guarantees that they
703 do not interfere with each other---an essential feature since builds are
704 regarded as pure functions (@pxref{Introduction}).
706 On a GNU/Linux system, a build user pool may be created like this (using
707 Bash syntax and the @code{shadow} commands):
709 @c See http://lists.gnu.org/archive/html/bug-guix/2013-01/msg00239.html
710 @c for why `-G' is needed.
712 # groupadd --system guixbuild
713 # for i in `seq -w 1 10`;
715 useradd -g guixbuild -G guixbuild \
716 -d /var/empty -s `which nologin` \
717 -c "Guix build user $i" --system \
723 The number of build users determines how many build jobs may run in
724 parallel, as specified by the @option{--max-jobs} option
725 (@pxref{Invoking guix-daemon, @option{--max-jobs}}). To use
726 @command{guix system vm} and related commands, you may need to add the
727 build users to the @code{kvm} group so they can access @file{/dev/kvm},
728 using @code{-G guixbuild,kvm} instead of @code{-G guixbuild}
729 (@pxref{Invoking guix system}).
731 The @code{guix-daemon} program may then be run as @code{root} with the
732 following command@footnote{If your machine uses the systemd init system,
733 dropping the @file{@var{prefix}/lib/systemd/system/guix-daemon.service}
734 file in @file{/etc/systemd/system} will ensure that
735 @command{guix-daemon} is automatically started. Similarly, if your
736 machine uses the Upstart init system, drop the
737 @file{@var{prefix}/lib/upstart/system/guix-daemon.conf}
738 file in @file{/etc/init}.}:
741 # guix-daemon --build-users-group=guixbuild
746 This way, the daemon starts build processes in a chroot, under one of
747 the @code{guixbuilder} users. On GNU/Linux, by default, the chroot
748 environment contains nothing but:
750 @c Keep this list in sync with libstore/build.cc! -----------------------
753 a minimal @code{/dev} directory, created mostly independently from the
754 host @code{/dev}@footnote{``Mostly'', because while the set of files
755 that appear in the chroot's @code{/dev} is fixed, most of these files
756 can only be created if the host has them.};
759 the @code{/proc} directory; it only shows the processes of the container
760 since a separate PID name space is used;
763 @file{/etc/passwd} with an entry for the current user and an entry for
767 @file{/etc/group} with an entry for the user's group;
770 @file{/etc/hosts} with an entry that maps @code{localhost} to
774 a writable @file{/tmp} directory.
777 You can influence the directory where the daemon stores build trees
778 @i{via} the @code{TMPDIR} environment variable. However, the build tree
779 within the chroot is always called @file{/tmp/guix-build-@var{name}.drv-0},
780 where @var{name} is the derivation name---e.g., @code{coreutils-8.24}.
781 This way, the value of @code{TMPDIR} does not leak inside build
782 environments, which avoids discrepancies in cases where build processes
783 capture the name of their build tree.
786 The daemon also honors the @code{http_proxy} environment variable for
787 HTTP downloads it performs, be it for fixed-output derivations
788 (@pxref{Derivations}) or for substitutes (@pxref{Substitutes}).
790 If you are installing Guix as an unprivileged user, it is still possible
791 to run @command{guix-daemon} provided you pass @code{--disable-chroot}.
792 However, build processes will not be isolated from one another, and not
793 from the rest of the system. Thus, build processes may interfere with
794 each other, and may access programs, libraries, and other files
795 available on the system---making it much harder to view them as
796 @emph{pure} functions.
799 @node Daemon Offload Setup
800 @subsection Using the Offload Facility
804 When desired, the build daemon can @dfn{offload}
805 derivation builds to other machines
806 running Guix, using the @code{offload} @dfn{build hook}. When that
807 feature is enabled, a list of user-specified build machines is read from
808 @file{/etc/guix/machines.scm}; every time a build is requested, for
809 instance via @code{guix build}, the daemon attempts to offload it to one
810 of the machines that satisfy the constraints of the derivation, in
811 particular its system type---e.g., @file{x86_64-linux}. Missing
812 prerequisites for the build are copied over SSH to the target machine,
813 which then proceeds with the build; upon success the output(s) of the
814 build are copied back to the initial machine.
816 The @file{/etc/guix/machines.scm} file typically looks like this:
820 (name "eightysix.example.org")
821 (system "x86_64-linux")
823 (speed 2.)) ; incredibly fast!
826 (name "meeps.example.org")
827 (system "mips64el-linux")
830 (string-append (getenv "HOME")
831 "/.lsh/identity-for-guix"))))
835 In the example above we specify a list of two build machines, one for
836 the @code{x86_64} architecture and one for the @code{mips64el}
839 In fact, this file is---not surprisingly!---a Scheme file that is
840 evaluated when the @code{offload} hook is started. Its return value
841 must be a list of @code{build-machine} objects. While this example
842 shows a fixed list of build machines, one could imagine, say, using
843 DNS-SD to return a list of potential build machines discovered in the
844 local network (@pxref{Introduction, Guile-Avahi,, guile-avahi, Using
845 Avahi in Guile Scheme Programs}). The @code{build-machine} data type is
848 @deftp {Data Type} build-machine
849 This data type represents build machines to which the daemon may offload
850 builds. The important fields are:
855 The host name of the remote machine.
858 The system type of the remote machine---e.g., @code{"x86_64-linux"}.
861 The user account to use when connecting to the remote machine over SSH.
862 Note that the SSH key pair must @emph{not} be passphrase-protected, to
863 allow non-interactive logins.
867 A number of optional fields may be specified:
872 Port number of SSH server on the machine (default: 22).
875 The SSH private key file to use when connecting to the machine.
877 Currently offloading uses GNU@tie{}lsh as its SSH client
878 (@pxref{Invoking lsh,,, GNU lsh Manual}). Thus, the key file here must
879 be an lsh key file. This may change in the future, though.
881 @item parallel-builds
882 The number of builds that may run in parallel on the machine (1 by
886 A ``relative speed factor''. The offload scheduler will tend to prefer
887 machines with a higher speed factor.
890 A list of strings denoting specific features supported by the machine.
891 An example is @code{"kvm"} for machines that have the KVM Linux modules
892 and corresponding hardware support. Derivations can request features by
893 name, and they will be scheduled on matching build machines.
898 The @code{guix} command must be in the search path on the build
899 machines, since offloading works by invoking the @code{guix archive} and
900 @code{guix build} commands. In addition, the Guix modules must be in
901 @code{$GUILE_LOAD_PATH} on the build machine---you can check whether
902 this is the case by running:
905 lsh build-machine guile -c "'(use-modules (guix config))'"
908 There is one last thing to do once @file{machines.scm} is in place. As
909 explained above, when offloading, files are transferred back and forth
910 between the machine stores. For this to work, you first need to
911 generate a key pair on each machine to allow the daemon to export signed
912 archives of files from the store (@pxref{Invoking guix archive}):
915 # guix archive --generate-key
919 Each build machine must authorize the key of the master machine so that
920 it accepts store items it receives from the master:
923 # guix archive --authorize < master-public-key.txt
927 Likewise, the master machine must authorize the key of each build machine.
929 All the fuss with keys is here to express pairwise mutual trust
930 relations between the master and the build machines. Concretely, when
931 the master receives files from a build machine (and @i{vice versa}), its
932 build daemon can make sure they are genuine, have not been tampered
933 with, and that they are signed by an authorized key.
936 @node Invoking guix-daemon
937 @section Invoking @command{guix-daemon}
939 The @command{guix-daemon} program implements all the functionality to
940 access the store. This includes launching build processes, running the
941 garbage collector, querying the availability of a build result, etc. It
942 is normally run as @code{root} like this:
945 # guix-daemon --build-users-group=guixbuild
949 For details on how to set it up, @pxref{Setting Up the Daemon}.
952 @cindex container, build environment
953 @cindex build environment
954 @cindex reproducible builds
955 By default, @command{guix-daemon} launches build processes under
956 different UIDs, taken from the build group specified with
957 @code{--build-users-group}. In addition, each build process is run in a
958 chroot environment that only contains the subset of the store that the
959 build process depends on, as specified by its derivation
960 (@pxref{Programming Interface, derivation}), plus a set of specific
961 system directories. By default, the latter contains @file{/dev} and
962 @file{/dev/pts}. Furthermore, on GNU/Linux, the build environment is a
963 @dfn{container}: in addition to having its own file system tree, it has
964 a separate mount name space, its own PID name space, network name space,
965 etc. This helps achieve reproducible builds (@pxref{Features}).
967 When the daemon performs a build on behalf of the user, it creates a
968 build directory under @file{/tmp} or under the directory specified by
969 its @code{TMPDIR} environment variable; this directory is shared with
970 the container for the duration of the build. Be aware that using a
971 directory other than @file{/tmp} can affect build results---for example,
972 with a longer directory name, a build process that uses Unix-domain
973 sockets might hit the name length limitation for @code{sun_path}, which
974 it would otherwise not hit.
976 The build directory is automatically deleted upon completion, unless the
977 build failed and the client specified @option{--keep-failed}
978 (@pxref{Invoking guix build, @option{--keep-failed}}).
980 The following command-line options are supported:
983 @item --build-users-group=@var{group}
984 Take users from @var{group} to run build processes (@pxref{Setting Up
985 the Daemon, build users}).
987 @item --no-substitutes
989 Do not use substitutes for build products. That is, always build things
990 locally instead of allowing downloads of pre-built binaries
991 (@pxref{Substitutes}).
993 By default substitutes are used, unless the client---such as the
994 @command{guix package} command---is explicitly invoked with
995 @code{--no-substitutes}.
997 When the daemon runs with @code{--no-substitutes}, clients can still
998 explicitly enable substitution @i{via} the @code{set-build-options}
999 remote procedure call (@pxref{The Store}).
1001 @item --substitute-urls=@var{urls}
1002 @anchor{daemon-substitute-urls}
1003 Consider @var{urls} the default whitespace-separated list of substitute
1004 source URLs. When this option is omitted,
1005 @indicateurl{https://mirror.hydra.gnu.org https://hydra.gnu.org} is used
1006 (@code{mirror.hydra.gnu.org} is a mirror of @code{hydra.gnu.org}).
1008 This means that substitutes may be downloaded from @var{urls}, as long
1009 as they are signed by a trusted signature (@pxref{Substitutes}).
1012 @item --no-build-hook
1013 Do not use the @dfn{build hook}.
1015 The build hook is a helper program that the daemon can start and to
1016 which it submits build requests. This mechanism is used to offload
1017 builds to other machines (@pxref{Daemon Offload Setup}).
1019 @item --cache-failures
1020 Cache build failures. By default, only successful builds are cached.
1022 When this option is used, @command{guix gc --list-failures} can be used
1023 to query the set of store items marked as failed; @command{guix gc
1024 --clear-failures} removes store items from the set of cached failures.
1025 @xref{Invoking guix gc}.
1027 @item --cores=@var{n}
1029 Use @var{n} CPU cores to build each derivation; @code{0} means as many
1032 The default value is @code{0}, but it may be overridden by clients, such
1033 as the @code{--cores} option of @command{guix build} (@pxref{Invoking
1036 The effect is to define the @code{NIX_BUILD_CORES} environment variable
1037 in the build process, which can then use it to exploit internal
1038 parallelism---for instance, by running @code{make -j$NIX_BUILD_CORES}.
1040 @item --max-jobs=@var{n}
1042 Allow at most @var{n} build jobs in parallel. The default value is
1043 @code{1}. Setting it to @code{0} means that no builds will be performed
1044 locally; instead, the daemon will offload builds (@pxref{Daemon Offload
1045 Setup}), or simply fail.
1047 @item --rounds=@var{N}
1048 Build each derivation @var{n} times in a row, and raise an error if
1049 consecutive build results are not bit-for-bit identical. Note that this
1050 setting can be overridden by clients such as @command{guix build}
1051 (@pxref{Invoking guix build}).
1053 When used in conjunction with @option{--keep-failed}, the differing
1054 output is kept in the store, under @file{/gnu/store/@dots{}-check}.
1055 This makes it easy to look for differences between the two results.
1058 Produce debugging output.
1060 This is useful to debug daemon start-up issues, but then it may be
1061 overridden by clients, for example the @code{--verbosity} option of
1062 @command{guix build} (@pxref{Invoking guix build}).
1064 @item --chroot-directory=@var{dir}
1065 Add @var{dir} to the build chroot.
1067 Doing this may change the result of build processes---for instance if
1068 they use optional dependencies found in @var{dir} when it is available,
1069 and not otherwise. For that reason, it is not recommended to do so.
1070 Instead, make sure that each derivation declares all the inputs that it
1073 @item --disable-chroot
1074 Disable chroot builds.
1076 Using this option is not recommended since, again, it would allow build
1077 processes to gain access to undeclared dependencies. It is necessary,
1078 though, when @command{guix-daemon} is running under an unprivileged user
1081 @item --disable-log-compression
1082 Disable compression of the build logs.
1084 Unless @code{--lose-logs} is used, all the build logs are kept in the
1085 @var{localstatedir}. To save space, the daemon automatically compresses
1086 them with bzip2 by default. This option disables that.
1088 @item --disable-deduplication
1089 @cindex deduplication
1090 Disable automatic file ``deduplication'' in the store.
1092 By default, files added to the store are automatically ``deduplicated'':
1093 if a newly added file is identical to another one found in the store,
1094 the daemon makes the new file a hard link to the other file. This can
1095 noticeably reduce disk usage, at the expense of slightly increased
1096 input/output load at the end of a build process. This option disables
1099 @item --gc-keep-outputs[=yes|no]
1100 Tell whether the garbage collector (GC) must keep outputs of live
1103 When set to ``yes'', the GC will keep the outputs of any live derivation
1104 available in the store---the @code{.drv} files. The default is ``no'',
1105 meaning that derivation outputs are kept only if they are GC roots.
1107 @item --gc-keep-derivations[=yes|no]
1108 Tell whether the garbage collector (GC) must keep derivations
1109 corresponding to live outputs.
1111 When set to ``yes'', as is the case by default, the GC keeps
1112 derivations---i.e., @code{.drv} files---as long as at least one of their
1113 outputs is live. This allows users to keep track of the origins of
1114 items in their store. Setting it to ``no'' saves a bit of disk space.
1116 Note that when both @code{--gc-keep-derivations} and
1117 @code{--gc-keep-outputs} are used, the effect is to keep all the build
1118 prerequisites (the sources, compiler, libraries, and other build-time
1119 tools) of live objects in the store, regardless of whether these
1120 prerequisites are live. This is convenient for developers since it
1121 saves rebuilds or downloads.
1123 @item --impersonate-linux-2.6
1124 On Linux-based systems, impersonate Linux 2.6. This means that the
1125 kernel's @code{uname} system call will report 2.6 as the release number.
1127 This might be helpful to build programs that (usually wrongfully) depend
1128 on the kernel version number.
1131 Do not keep build logs. By default they are kept under
1132 @code{@var{localstatedir}/guix/log}.
1134 @item --system=@var{system}
1135 Assume @var{system} as the current system type. By default it is the
1136 architecture/kernel pair found at configure time, such as
1137 @code{x86_64-linux}.
1139 @item --listen=@var{socket}
1140 Listen for connections on @var{socket}, the file name of a Unix-domain
1141 socket. The default socket is
1142 @file{@var{localstatedir}/daemon-socket/socket}. This option is only
1143 useful in exceptional circumstances, such as if you need to run several
1144 daemons on the same machine.
1148 @node Application Setup
1149 @section Application Setup
1151 @cindex foreign distro
1152 When using Guix on top of GNU/Linux distribution other than GuixSD---a
1153 so-called @dfn{foreign distro}---a few additional steps are needed to
1154 get everything in place. Here are some of them.
1158 @anchor{locales-and-locpath}
1159 @cindex locales, when not on GuixSD
1161 @vindex GUIX_LOCPATH
1162 Packages installed @i{via} Guix will not use the locale data of the
1163 host system. Instead, you must first install one of the locale packages
1164 available with Guix and then define the @code{GUIX_LOCPATH} environment
1168 $ guix package -i glibc-locales
1169 $ export GUIX_LOCPATH=$HOME/.guix-profile/lib/locale
1172 Note that the @code{glibc-locales} package contains data for all the
1173 locales supported by the GNU@tie{}libc and weighs in at around
1174 110@tie{}MiB. Alternatively, the @code{glibc-utf8-locales} is smaller but
1175 limited to a few UTF-8 locales.
1177 The @code{GUIX_LOCPATH} variable plays a role similar to @code{LOCPATH}
1178 (@pxref{Locale Names, @code{LOCPATH},, libc, The GNU C Library Reference
1179 Manual}). There are two important differences though:
1183 @code{GUIX_LOCPATH} is honored only by the libc in Guix, and not by the libc
1184 provided by foreign distros. Thus, using @code{GUIX_LOCPATH} allows you
1185 to make sure the programs of the foreign distro will not end up loading
1186 incompatible locale data.
1189 libc suffixes each entry of @code{GUIX_LOCPATH} with @code{/X.Y}, where
1190 @code{X.Y} is the libc version---e.g., @code{2.22}. This means that,
1191 should your Guix profile contain a mixture of programs linked against
1192 different libc version, each libc version will only try to load locale
1193 data in the right format.
1196 This is important because the locale data format used by different libc
1197 versions may be incompatible.
1199 @subsection X11 Fonts
1201 The majority of graphical applications use Fontconfig to locate and
1202 load fonts and perform X11-client-side rendering. The @code{fontconfig}
1203 package in Guix looks for fonts in @file{$HOME/.guix-profile}
1204 by default. Thus, to allow graphical applications installed with Guix
1205 to display fonts, you have to install fonts with Guix as well.
1206 Essential font packages include @code{gs-fonts}, @code{font-dejavu}, and
1207 @code{font-gnu-freefont-ttf}.
1209 To display text written in Chinese languages, Japanese, or Korean in
1210 graphical applications, consider installing
1211 @code{font-adobe-source-han-sans} or @code{font-wqy-zenhei}. The former
1212 has multiple outputs, one per language family (@pxref{Packages with
1213 Multiple Outputs}). For instance, the following command installs fonts
1214 for Chinese languages:
1217 guix package -i font-adobe-source-han-sans:cn
1220 Older programs such as @command{xterm} do not use Fontconfig and instead
1221 rely on server-side font rendering. Such programs require to specify a
1222 full name of a font using XLFD (X Logical Font Description), like this:
1225 -*-dejavu sans-medium-r-normal-*-*-100-*-*-*-*-*-1
1228 To be able to use such full names for the TrueType fonts installed in
1229 your Guix profile, you need to extend the font path of the X server:
1232 xset +fp ~/.guix-profile/share/fonts/truetype
1235 After that, you can run @code{xlsfonts} (from @code{xlsfonts} package)
1236 to make sure your TrueType fonts are listed there.
1238 @subsection X.509 Certificates
1240 The @code{nss-certs} package provides X.509 certificates, which allow
1241 programs to authenticate Web servers accessed over HTTPS.
1243 When using Guix on a foreign distro, you can install this package and
1244 define the relevant environment variables so that packages know where to
1245 look for certificates. @xref{X.509 Certificates}, for detailed
1248 @subsection Emacs Packages
1250 When you install Emacs packages with Guix, the elisp files may be placed
1251 either in @file{$HOME/.guix-profile/share/emacs/site-lisp/} or in
1253 @file{$HOME/.guix-profile/share/emacs/site-lisp/guix.d/}. The latter
1254 directory exists because potentially there may exist thousands of Emacs
1255 packages and storing all their files in a single directory may be not
1256 reliable (because of name conflicts). So we think using a separate
1257 directory for each package is a good idea. It is very similar to how
1258 the Emacs package system organizes the file structure (@pxref{Package
1259 Files,,, emacs, The GNU Emacs Manual}).
1261 By default, Emacs (installed with Guix) ``knows'' where these packages
1262 are placed, so you do not need to perform any configuration. If, for
1263 some reason, you want to avoid auto-loading Emacs packages installed
1264 with Guix, you can do so by running Emacs with @code{--no-site-file}
1265 option (@pxref{Init File,,, emacs, The GNU Emacs Manual}).
1269 @c *********************************************************************
1270 @node Package Management
1271 @chapter Package Management
1273 The purpose of GNU Guix is to allow users to easily install, upgrade, and
1274 remove software packages, without having to know about their build
1275 procedures or dependencies. Guix also goes beyond this obvious set of
1278 This chapter describes the main features of Guix, as well as the package
1279 management tools it provides. Two user interfaces are provided for
1280 routine package management tasks: A command-line interface described below
1281 (@pxref{Invoking guix package, @code{guix package}}), as well as a visual user
1282 interface in Emacs described in a subsequent chapter (@pxref{Emacs Interface}).
1285 * Features:: How Guix will make your life brighter.
1286 * Invoking guix package:: Package installation, removal, etc.
1287 * Substitutes:: Downloading pre-built binaries.
1288 * Packages with Multiple Outputs:: Single source package, multiple outputs.
1289 * Invoking guix gc:: Running the garbage collector.
1290 * Invoking guix pull:: Fetching the latest Guix and distribution.
1291 * Invoking guix archive:: Exporting and importing store files.
1297 When using Guix, each package ends up in the @dfn{package store}, in its
1298 own directory---something that resembles
1299 @file{/gnu/store/xxx-package-1.2}, where @code{xxx} is a base32 string
1300 (note that Guix comes with an Emacs extension to shorten those file
1301 names, @pxref{Emacs Prettify}.)
1303 Instead of referring to these directories, users have their own
1304 @dfn{profile}, which points to the packages that they actually want to
1305 use. These profiles are stored within each user's home directory, at
1306 @code{$HOME/.guix-profile}.
1308 For example, @code{alice} installs GCC 4.7.2. As a result,
1309 @file{/home/alice/.guix-profile/bin/gcc} points to
1310 @file{/gnu/store/@dots{}-gcc-4.7.2/bin/gcc}. Now, on the same machine,
1311 @code{bob} had already installed GCC 4.8.0. The profile of @code{bob}
1312 simply continues to point to
1313 @file{/gnu/store/@dots{}-gcc-4.8.0/bin/gcc}---i.e., both versions of GCC
1314 coexist on the same system without any interference.
1316 The @command{guix package} command is the central tool to manage
1317 packages (@pxref{Invoking guix package}). It operates on the per-user
1318 profiles, and can be used @emph{with normal user privileges}.
1320 The command provides the obvious install, remove, and upgrade
1321 operations. Each invocation is actually a @emph{transaction}: either
1322 the specified operation succeeds, or nothing happens. Thus, if the
1323 @command{guix package} process is terminated during the transaction,
1324 or if a power outage occurs during the transaction, then the user's
1325 profile remains in its previous state, and remains usable.
1327 In addition, any package transaction may be @emph{rolled back}. So, if,
1328 for example, an upgrade installs a new version of a package that turns
1329 out to have a serious bug, users may roll back to the previous instance
1330 of their profile, which was known to work well. Similarly, the global
1331 system configuration on GuixSD is subject to
1332 transactional upgrades and roll-back
1333 (@pxref{Using the Configuration System}).
1335 All packages in the package store may be @emph{garbage-collected}.
1336 Guix can determine which packages are still referenced by user
1337 profiles, and remove those that are provably no longer referenced
1338 (@pxref{Invoking guix gc}). Users may also explicitly remove old
1339 generations of their profile so that the packages they refer to can be
1342 @cindex reproducibility
1343 @cindex reproducible builds
1344 Finally, Guix takes a @dfn{purely functional} approach to package
1345 management, as described in the introduction (@pxref{Introduction}).
1346 Each @file{/gnu/store} package directory name contains a hash of all the
1347 inputs that were used to build that package---compiler, libraries, build
1348 scripts, etc. This direct correspondence allows users to make sure a
1349 given package installation matches the current state of their
1350 distribution. It also helps maximize @dfn{build reproducibility}:
1351 thanks to the isolated build environments that are used, a given build
1352 is likely to yield bit-identical files when performed on different
1353 machines (@pxref{Invoking guix-daemon, container}).
1356 This foundation allows Guix to support @dfn{transparent binary/source
1357 deployment}. When a pre-built binary for a @file{/gnu/store} item is
1358 available from an external source---a @dfn{substitute}, Guix just
1359 downloads it and unpacks it;
1360 otherwise, it builds the package from source, locally
1361 (@pxref{Substitutes}). Because build results are usually bit-for-bit
1362 reproducible, users do not have to trust servers that provide
1363 substitutes: they can force a local build and @emph{challenge} providers
1364 (@pxref{Invoking guix challenge}).
1366 Control over the build environment is a feature that is also useful for
1367 developers. The @command{guix environment} command allows developers of
1368 a package to quickly set up the right development environment for their
1369 package, without having to manually install the dependencies of the
1370 package into their profile (@pxref{Invoking guix environment}).
1372 @node Invoking guix package
1373 @section Invoking @command{guix package}
1375 The @command{guix package} command is the tool that allows users to
1376 install, upgrade, and remove packages, as well as rolling back to
1377 previous configurations. It operates only on the user's own profile,
1378 and works with normal user privileges (@pxref{Features}). Its syntax
1382 guix package @var{options}
1385 Primarily, @var{options} specifies the operations to be performed during
1386 the transaction. Upon completion, a new profile is created, but
1387 previous @dfn{generations} of the profile remain available, should the user
1390 For example, to remove @code{lua} and install @code{guile} and
1391 @code{guile-cairo} in a single transaction:
1394 guix package -r lua -i guile guile-cairo
1397 @command{guix package} also supports a @dfn{declarative approach}
1398 whereby the user specifies the exact set of packages to be available and
1399 passes it @i{via} the @option{--manifest} option
1400 (@pxref{profile-manifest, @option{--manifest}}).
1402 For each user, a symlink to the user's default profile is automatically
1403 created in @file{$HOME/.guix-profile}. This symlink always points to the
1404 current generation of the user's default profile. Thus, users can add
1405 @file{$HOME/.guix-profile/bin} to their @code{PATH} environment
1406 variable, and so on.
1407 @cindex search paths
1408 If you are not using the Guix System Distribution, consider adding the
1409 following lines to your @file{~/.bash_profile} (@pxref{Bash Startup
1410 Files,,, bash, The GNU Bash Reference Manual}) so that newly-spawned
1411 shells get all the right environment variable definitions:
1414 GUIX_PROFILE="$HOME/.guix-profile" \
1415 source "$HOME/.guix-profile/etc/profile"
1418 In a multi-user setup, user profiles are stored in a place registered as
1419 a @dfn{garbage-collector root}, which @file{$HOME/.guix-profile} points
1420 to (@pxref{Invoking guix gc}). That directory is normally
1421 @code{@var{localstatedir}/profiles/per-user/@var{user}}, where
1422 @var{localstatedir} is the value passed to @code{configure} as
1423 @code{--localstatedir}, and @var{user} is the user name. The
1424 @file{per-user} directory is created when @command{guix-daemon} is
1425 started, and the @var{user} sub-directory is created by @command{guix
1428 The @var{options} can be among the following:
1432 @item --install=@var{package} @dots{}
1433 @itemx -i @var{package} @dots{}
1434 Install the specified @var{package}s.
1436 Each @var{package} may specify either a simple package name, such as
1437 @code{guile}, or a package name followed by an at-sign and version number,
1438 such as @code{guile@@1.8.8} or simply @code{guile@@1.8} (in the latter
1439 case, the newest version prefixed by @code{1.8} is selected.)
1441 If no version number is specified, the
1442 newest available version will be selected. In addition, @var{package}
1443 may contain a colon, followed by the name of one of the outputs of the
1444 package, as in @code{gcc:doc} or @code{binutils@@2.22:lib}
1445 (@pxref{Packages with Multiple Outputs}). Packages with a corresponding
1446 name (and optionally version) are searched for among the GNU
1447 distribution modules (@pxref{Package Modules}).
1449 @cindex propagated inputs
1450 Sometimes packages have @dfn{propagated inputs}: these are dependencies
1451 that automatically get installed along with the required package
1452 (@pxref{package-propagated-inputs, @code{propagated-inputs} in
1453 @code{package} objects}, for information about propagated inputs in
1454 package definitions).
1456 @anchor{package-cmd-propagated-inputs}
1457 An example is the GNU MPC library: its C header files refer to those of
1458 the GNU MPFR library, which in turn refer to those of the GMP library.
1459 Thus, when installing MPC, the MPFR and GMP libraries also get installed
1460 in the profile; removing MPC also removes MPFR and GMP---unless they had
1461 also been explicitly installed by the user.
1463 Besides, packages sometimes rely on the definition of environment
1464 variables for their search paths (see explanation of
1465 @code{--search-paths} below). Any missing or possibly incorrect
1466 environment variable definitions are reported here.
1468 @item --install-from-expression=@var{exp}
1470 Install the package @var{exp} evaluates to.
1472 @var{exp} must be a Scheme expression that evaluates to a
1473 @code{<package>} object. This option is notably useful to disambiguate
1474 between same-named variants of a package, with expressions such as
1475 @code{(@@ (gnu packages base) guile-final)}.
1477 Note that this option installs the first output of the specified
1478 package, which may be insufficient when needing a specific output of a
1479 multiple-output package.
1481 @item --install-from-file=@var{file}
1482 @itemx -f @var{file}
1483 Install the package that the code within @var{file} evaluates to.
1485 As an example, @var{file} might contain a definition like this
1486 (@pxref{Defining Packages}):
1489 @verbatiminclude package-hello.scm
1492 Developers may find it useful to include such a @file{guix.scm} file
1493 in the root of their project source tree that can be used to test
1494 development snapshots and create reproducible development environments
1495 (@pxref{Invoking guix environment}).
1497 @item --remove=@var{package} @dots{}
1498 @itemx -r @var{package} @dots{}
1499 Remove the specified @var{package}s.
1501 As for @code{--install}, each @var{package} may specify a version number
1502 and/or output name in addition to the package name. For instance,
1503 @code{-r glibc:debug} would remove the @code{debug} output of
1506 @item --upgrade[=@var{regexp} @dots{}]
1507 @itemx -u [@var{regexp} @dots{}]
1508 Upgrade all the installed packages. If one or more @var{regexp}s are
1509 specified, upgrade only installed packages whose name matches a
1510 @var{regexp}. Also see the @code{--do-not-upgrade} option below.
1512 Note that this upgrades package to the latest version of packages found
1513 in the distribution currently installed. To update your distribution,
1514 you should regularly run @command{guix pull} (@pxref{Invoking guix
1517 @item --do-not-upgrade[=@var{regexp} @dots{}]
1518 When used together with the @code{--upgrade} option, do @emph{not}
1519 upgrade any packages whose name matches a @var{regexp}. For example, to
1520 upgrade all packages in the current profile except those containing the
1521 substring ``emacs'':
1524 $ guix package --upgrade . --do-not-upgrade emacs
1527 @item @anchor{profile-manifest}--manifest=@var{file}
1528 @itemx -m @var{file}
1529 @cindex profile declaration
1530 @cindex profile manifest
1531 Create a new generation of the profile from the manifest object
1532 returned by the Scheme code in @var{file}.
1534 This allows you to @emph{declare} the profile's contents rather than
1535 constructing it through a sequence of @code{--install} and similar
1536 commands. The advantage is that @var{file} can be put under version
1537 control, copied to different machines to reproduce the same profile, and
1540 @c FIXME: Add reference to (guix profile) documentation when available.
1541 @var{file} must return a @dfn{manifest} object, which is roughly a list
1544 @findex packages->manifest
1546 (use-package-modules guile emacs)
1551 ;; Use a specific package output.
1552 (list guile-2.0 "debug")))
1556 Roll back to the previous @dfn{generation} of the profile---i.e., undo
1557 the last transaction.
1559 When combined with options such as @code{--install}, roll back occurs
1560 before any other actions.
1562 When rolling back from the first generation that actually contains
1563 installed packages, the profile is made to point to the @dfn{zeroth
1564 generation}, which contains no files apart from its own metadata.
1566 After having rolled back, installing, removing, or upgrading packages
1567 overwrites previous future generations. Thus, the history of the
1568 generations in a profile is always linear.
1570 @item --switch-generation=@var{pattern}
1571 @itemx -S @var{pattern}
1572 Switch to a particular generation defined by @var{pattern}.
1574 @var{pattern} may be either a generation number or a number prefixed
1575 with ``+'' or ``-''. The latter means: move forward/backward by a
1576 specified number of generations. For example, if you want to return to
1577 the latest generation after @code{--roll-back}, use
1578 @code{--switch-generation=+1}.
1580 The difference between @code{--roll-back} and
1581 @code{--switch-generation=-1} is that @code{--switch-generation} will
1582 not make a zeroth generation, so if a specified generation does not
1583 exist, the current generation will not be changed.
1585 @item --search-paths[=@var{kind}]
1586 @cindex search paths
1587 Report environment variable definitions, in Bash syntax, that may be
1588 needed in order to use the set of installed packages. These environment
1589 variables are used to specify @dfn{search paths} for files used by some
1590 of the installed packages.
1592 For example, GCC needs the @code{CPATH} and @code{LIBRARY_PATH}
1593 environment variables to be defined so it can look for headers and
1594 libraries in the user's profile (@pxref{Environment Variables,,, gcc,
1595 Using the GNU Compiler Collection (GCC)}). If GCC and, say, the C
1596 library are installed in the profile, then @code{--search-paths} will
1597 suggest setting these variables to @code{@var{profile}/include} and
1598 @code{@var{profile}/lib}, respectively.
1600 The typical use case is to define these environment variables in the
1604 $ eval `guix package --search-paths`
1607 @var{kind} may be one of @code{exact}, @code{prefix}, or @code{suffix},
1608 meaning that the returned environment variable definitions will either
1609 be exact settings, or prefixes or suffixes of the current value of these
1610 variables. When omitted, @var{kind} defaults to @code{exact}.
1612 This option can also be used to compute the @emph{combined} search paths
1613 of several profiles. Consider this example:
1616 $ guix package -p foo -i guile
1617 $ guix package -p bar -i guile-json
1618 $ guix package -p foo -p bar --search-paths
1621 The last command above reports about the @code{GUILE_LOAD_PATH}
1622 variable, even though, taken individually, neither @file{foo} nor
1623 @file{bar} would lead to that recommendation.
1626 @item --profile=@var{profile}
1627 @itemx -p @var{profile}
1628 Use @var{profile} instead of the user's default profile.
1631 Produce verbose output. In particular, emit the build log of the
1632 environment on the standard error port.
1635 Use the bootstrap Guile to build the profile. This option is only
1636 useful to distribution developers.
1640 In addition to these actions, @command{guix package} supports the
1641 following options to query the current state of a profile, or the
1642 availability of packages:
1646 @item --search=@var{regexp}
1647 @itemx -s @var{regexp}
1648 @cindex searching for packages
1649 List the available packages whose name, synopsis, or description matches
1650 @var{regexp}. Print all the metadata of matching packages in
1651 @code{recutils} format (@pxref{Top, GNU recutils databases,, recutils,
1652 GNU recutils manual}).
1654 This allows specific fields to be extracted using the @command{recsel}
1655 command, for instance:
1658 $ guix package -s malloc | recsel -p name,version
1666 Similarly, to show the name of all the packages available under the
1667 terms of the GNU@tie{}LGPL version 3:
1670 $ guix package -s "" | recsel -p name -e 'license ~ "LGPL 3"'
1677 It is also possible to refine search results using several @code{-s}
1678 flags. For example, the following command returns a list of board
1682 $ guix package -s '\<board\>' -s game | recsel -p name
1687 If we were to omit @code{-s game}, we would also get software packages
1688 that deal with printed circuit boards; removing the angle brackets
1689 around @code{board} would further add packages that have to do with
1692 And now for a more elaborate example. The following command searches
1693 for cryptographic libraries, filters out Haskell, Perl, Python, and Ruby
1694 libraries, and prints the name and synopsis of the matching packages:
1697 $ guix package -s crypto -s library | \
1698 recsel -e '! (name ~ "^(ghc|perl|python|ruby)")' -p name,synopsis
1702 @xref{Selection Expressions,,, recutils, GNU recutils manual}, for more
1703 information on @dfn{selection expressions} for @code{recsel -e}.
1705 @item --show=@var{package}
1706 Show details about @var{package}, taken from the list of available packages, in
1707 @code{recutils} format (@pxref{Top, GNU recutils databases,, recutils, GNU
1711 $ guix package --show=python | recsel -p name,version
1719 You may also specify the full name of a package to only get details about a
1720 specific version of it:
1722 $ guix package --show=python@@3.4 | recsel -p name,version
1729 @item --list-installed[=@var{regexp}]
1730 @itemx -I [@var{regexp}]
1731 List the currently installed packages in the specified profile, with the
1732 most recently installed packages shown last. When @var{regexp} is
1733 specified, list only installed packages whose name matches @var{regexp}.
1735 For each installed package, print the following items, separated by
1736 tabs: the package name, its version string, the part of the package that
1737 is installed (for instance, @code{out} for the default output,
1738 @code{include} for its headers, etc.), and the path of this package in
1741 @item --list-available[=@var{regexp}]
1742 @itemx -A [@var{regexp}]
1743 List packages currently available in the distribution for this system
1744 (@pxref{GNU Distribution}). When @var{regexp} is specified, list only
1745 installed packages whose name matches @var{regexp}.
1747 For each package, print the following items separated by tabs: its name,
1748 its version string, the parts of the package (@pxref{Packages with
1749 Multiple Outputs}), and the source location of its definition.
1751 @item --list-generations[=@var{pattern}]
1752 @itemx -l [@var{pattern}]
1753 Return a list of generations along with their creation dates; for each
1754 generation, show the installed packages, with the most recently
1755 installed packages shown last. Note that the zeroth generation is never
1758 For each installed package, print the following items, separated by
1759 tabs: the name of a package, its version string, the part of the package
1760 that is installed (@pxref{Packages with Multiple Outputs}), and the
1761 location of this package in the store.
1763 When @var{pattern} is used, the command returns only matching
1764 generations. Valid patterns include:
1767 @item @emph{Integers and comma-separated integers}. Both patterns denote
1768 generation numbers. For instance, @code{--list-generations=1} returns
1771 And @code{--list-generations=1,8,2} outputs three generations in the
1772 specified order. Neither spaces nor trailing commas are allowed.
1774 @item @emph{Ranges}. @code{--list-generations=2..9} prints the
1775 specified generations and everything in between. Note that the start of
1776 a range must be smaller than its end.
1778 It is also possible to omit the endpoint. For example,
1779 @code{--list-generations=2..}, returns all generations starting from the
1782 @item @emph{Durations}. You can also get the last @emph{N}@tie{}days, weeks,
1783 or months by passing an integer along with the first letter of the
1784 duration. For example, @code{--list-generations=20d} lists generations
1785 that are up to 20 days old.
1788 @item --delete-generations[=@var{pattern}]
1789 @itemx -d [@var{pattern}]
1790 When @var{pattern} is omitted, delete all generations except the current
1793 This command accepts the same patterns as @option{--list-generations}.
1794 When @var{pattern} is specified, delete the matching generations. When
1795 @var{pattern} specifies a duration, generations @emph{older} than the
1796 specified duration match. For instance, @code{--delete-generations=1m}
1797 deletes generations that are more than one month old.
1799 If the current generation matches, it is @emph{not} deleted. Also, the
1800 zeroth generation is never deleted.
1802 Note that deleting generations prevents rolling back to them.
1803 Consequently, this command must be used with care.
1807 Finally, since @command{guix package} may actually start build
1808 processes, it supports all the common build options (@pxref{Common Build
1809 Options}). It also supports package transformation options, such as
1810 @option{--with-source} (@pxref{Package Transformation Options}).
1811 However, note that package transformations are lost when upgrading; to
1812 preserve transformations across upgrades, you should define your own
1813 package variant in a Guile module and add it to @code{GUIX_PACKAGE_PATH}
1814 (@pxref{Defining Packages}).
1818 @section Substitutes
1821 @cindex pre-built binaries
1822 Guix supports transparent source/binary deployment, which means that it
1823 can either build things locally, or download pre-built items from a
1824 server. We call these pre-built items @dfn{substitutes}---they are
1825 substitutes for local build results. In many cases, downloading a
1826 substitute is much faster than building things locally.
1828 Substitutes can be anything resulting from a derivation build
1829 (@pxref{Derivations}). Of course, in the common case, they are
1830 pre-built package binaries, but source tarballs, for instance, which
1831 also result from derivation builds, can be available as substitutes.
1833 The @code{hydra.gnu.org} server is a front-end to a build farm that
1834 builds packages from the GNU distribution continuously for some
1835 architectures, and makes them available as substitutes (@pxref{Emacs
1836 Hydra}, for information on how to query the continuous integration
1837 server). This is the
1838 default source of substitutes; it can be overridden by passing the
1839 @option{--substitute-urls} option either to @command{guix-daemon}
1840 (@pxref{daemon-substitute-urls,, @code{guix-daemon --substitute-urls}})
1841 or to client tools such as @command{guix package}
1842 (@pxref{client-substitute-urls,, client @option{--substitute-urls}
1845 Substitute URLs can be either HTTP or HTTPS@footnote{For HTTPS access,
1846 the Guile bindings of GnuTLS must be installed. @xref{Requirements}.}
1847 HTTPS is recommended because communications are encrypted; conversely,
1848 using HTTP makes all communications visible to an eavesdropper, who
1849 could use the information gathered to determine, for instance, whether
1850 your system has unpatched security vulnerabilities.
1853 @cindex digital signatures
1854 To allow Guix to download substitutes from @code{hydra.gnu.org} or a
1856 must add its public key to the access control list (ACL) of archive
1857 imports, using the @command{guix archive} command (@pxref{Invoking guix
1858 archive}). Doing so implies that you trust @code{hydra.gnu.org} to not
1859 be compromised and to serve genuine substitutes.
1861 This public key is installed along with Guix, in
1862 @code{@var{prefix}/share/guix/hydra.gnu.org.pub}, where @var{prefix} is
1863 the installation prefix of Guix. If you installed Guix from source,
1864 make sure you checked the GPG signature of
1865 @file{guix-@value{VERSION}.tar.gz}, which contains this public key file.
1866 Then, you can run something like this:
1869 # guix archive --authorize < hydra.gnu.org.pub
1872 Once this is in place, the output of a command like @code{guix build}
1873 should change from something like:
1876 $ guix build emacs --dry-run
1877 The following derivations would be built:
1878 /gnu/store/yr7bnx8xwcayd6j95r2clmkdl1qh688w-emacs-24.3.drv
1879 /gnu/store/x8qsh1hlhgjx6cwsjyvybnfv2i37z23w-dbus-1.6.4.tar.gz.drv
1880 /gnu/store/1ixwp12fl950d15h2cj11c73733jay0z-alsa-lib-1.0.27.1.tar.bz2.drv
1881 /gnu/store/nlma1pw0p603fpfiqy7kn4zm105r5dmw-util-linux-2.21.drv
1889 $ guix build emacs --dry-run
1890 The following files would be downloaded:
1891 /gnu/store/pk3n22lbq6ydamyymqkkz7i69wiwjiwi-emacs-24.3
1892 /gnu/store/2ygn4ncnhrpr61rssa6z0d9x22si0va3-libjpeg-8d
1893 /gnu/store/71yz6lgx4dazma9dwn2mcjxaah9w77jq-cairo-1.12.16
1894 /gnu/store/7zdhgp0n1518lvfn8mb96sxqfmvqrl7v-libxrender-0.9.7
1899 This indicates that substitutes from @code{hydra.gnu.org} are usable and
1900 will be downloaded, when possible, for future builds.
1902 Guix ignores substitutes that are not signed, or that are not signed by
1903 one of the keys listed in the ACL. It also detects and raises an error
1904 when attempting to use a substitute that has been tampered with.
1907 Substitutes are downloaded over HTTP or HTTPS.
1908 The @code{http_proxy} environment
1909 variable can be set in the environment of @command{guix-daemon} and is
1910 honored for downloads of substitutes. Note that the value of
1911 @code{http_proxy} in the environment where @command{guix build},
1912 @command{guix package}, and other client commands are run has
1913 @emph{absolutely no effect}.
1915 When using HTTPS, the server's X.509 certificate is @emph{not} validated
1916 (in other words, the server is not authenticated), contrary to what
1917 HTTPS clients such as Web browsers usually do. This is because Guix
1918 authenticates substitute information itself, as explained above, which
1919 is what we care about (whereas X.509 certificates are about
1920 authenticating bindings between domain names and public keys.)
1922 The substitute mechanism can be disabled globally by running
1923 @code{guix-daemon} with @code{--no-substitutes} (@pxref{Invoking
1924 guix-daemon}). It can also be disabled temporarily by passing the
1925 @code{--no-substitutes} option to @command{guix package}, @command{guix
1926 build}, and other command-line tools.
1929 @unnumberedsubsec On Trusting Binaries
1931 Today, each individual's control over their own computing is at the
1932 mercy of institutions, corporations, and groups with enough power and
1933 determination to subvert the computing infrastructure and exploit its
1934 weaknesses. While using @code{hydra.gnu.org} substitutes can be
1935 convenient, we encourage users to also build on their own, or even run
1936 their own build farm, such that @code{hydra.gnu.org} is less of an
1937 interesting target. One way to help is by publishing the software you
1938 build using @command{guix publish} so that others have one more choice
1939 of server to download substitutes from (@pxref{Invoking guix publish}).
1941 Guix has the foundations to maximize build reproducibility
1942 (@pxref{Features}). In most cases, independent builds of a given
1943 package or derivation should yield bit-identical results. Thus, through
1944 a diverse set of independent package builds, we can strengthen the
1945 integrity of our systems. The @command{guix challenge} command aims to
1946 help users assess substitute servers, and to assist developers in
1947 finding out about non-deterministic package builds (@pxref{Invoking guix
1948 challenge}). Similarly, the @option{--check} option of @command{guix
1949 build} allows users to check whether previously-installed substitutes
1950 are genuine by rebuilding them locally (@pxref{build-check,
1951 @command{guix build --check}}).
1953 In the future, we want Guix to have support to publish and retrieve
1954 binaries to/from other users, in a peer-to-peer fashion. If you would
1955 like to discuss this project, join us on @email{guix-devel@@gnu.org}.
1958 @node Packages with Multiple Outputs
1959 @section Packages with Multiple Outputs
1961 @cindex multiple-output packages
1962 @cindex package outputs
1964 Often, packages defined in Guix have a single @dfn{output}---i.e., the
1965 source package leads to exactly one directory in the store. When running
1966 @command{guix package -i glibc}, one installs the default output of the
1967 GNU libc package; the default output is called @code{out}, but its name
1968 can be omitted as shown in this command. In this particular case, the
1969 default output of @code{glibc} contains all the C header files, shared
1970 libraries, static libraries, Info documentation, and other supporting
1973 Sometimes it is more appropriate to separate the various types of files
1974 produced from a single source package into separate outputs. For
1975 instance, the GLib C library (used by GTK+ and related packages)
1976 installs more than 20 MiB of reference documentation as HTML pages.
1977 To save space for users who do not need it, the documentation goes to a
1978 separate output, called @code{doc}. To install the main GLib output,
1979 which contains everything but the documentation, one would run:
1982 guix package -i glib
1985 The command to install its documentation is:
1988 guix package -i glib:doc
1991 Some packages install programs with different ``dependency footprints''.
1992 For instance, the WordNet package installs both command-line tools and
1993 graphical user interfaces (GUIs). The former depend solely on the C
1994 library, whereas the latter depend on Tcl/Tk and the underlying X
1995 libraries. In this case, we leave the command-line tools in the default
1996 output, whereas the GUIs are in a separate output. This allows users
1997 who do not need the GUIs to save space. The @command{guix size} command
1998 can help find out about such situations (@pxref{Invoking guix size}).
1999 @command{guix graph} can also be helpful (@pxref{Invoking guix graph}).
2001 There are several such multiple-output packages in the GNU distribution.
2002 Other conventional output names include @code{lib} for libraries and
2003 possibly header files, @code{bin} for stand-alone programs, and
2004 @code{debug} for debugging information (@pxref{Installing Debugging
2005 Files}). The outputs of a packages are listed in the third column of
2006 the output of @command{guix package --list-available} (@pxref{Invoking
2010 @node Invoking guix gc
2011 @section Invoking @command{guix gc}
2013 @cindex garbage collector
2014 Packages that are installed, but not used, may be @dfn{garbage-collected}.
2015 The @command{guix gc} command allows users to explicitly run the garbage
2016 collector to reclaim space from the @file{/gnu/store} directory. It is
2017 the @emph{only} way to remove files from @file{/gnu/store}---removing
2018 files or directories manually may break it beyond repair!
2020 The garbage collector has a set of known @dfn{roots}: any file under
2021 @file{/gnu/store} reachable from a root is considered @dfn{live} and
2022 cannot be deleted; any other file is considered @dfn{dead} and may be
2023 deleted. The set of garbage collector roots includes default user
2024 profiles, and may be augmented with @command{guix build --root}, for
2025 example (@pxref{Invoking guix build}).
2027 Prior to running @code{guix gc --collect-garbage} to make space, it is
2028 often useful to remove old generations from user profiles; that way, old
2029 package builds referenced by those generations can be reclaimed. This
2030 is achieved by running @code{guix package --delete-generations}
2031 (@pxref{Invoking guix package}).
2033 The @command{guix gc} command has three modes of operation: it can be
2034 used to garbage-collect any dead files (the default), to delete specific
2035 files (the @code{--delete} option), to print garbage-collector
2036 information, or for more advanced queries. The garbage collection
2037 options are as follows:
2040 @item --collect-garbage[=@var{min}]
2041 @itemx -C [@var{min}]
2042 Collect garbage---i.e., unreachable @file{/gnu/store} files and
2043 sub-directories. This is the default operation when no option is
2046 When @var{min} is given, stop once @var{min} bytes have been collected.
2047 @var{min} may be a number of bytes, or it may include a unit as a
2048 suffix, such as @code{MiB} for mebibytes and @code{GB} for gigabytes
2049 (@pxref{Block size, size specifications,, coreutils, GNU Coreutils}).
2051 When @var{min} is omitted, collect all the garbage.
2053 @item --free-space=@var{free}
2054 @itemx -F @var{free}
2055 Collect garbage until @var{free} space is available under
2056 @file{/gnu/store}, if possible; @var{free} denotes storage space, such
2057 as @code{500MiB}, as described above.
2059 When @var{free} or more is already available in @file{/gnu/store}, do
2060 nothing and exit immediately.
2064 Attempt to delete all the store files and directories specified as
2065 arguments. This fails if some of the files are not in the store, or if
2066 they are still live.
2068 @item --list-failures
2069 List store items corresponding to cached build failures.
2071 This prints nothing unless the daemon was started with
2072 @option{--cache-failures} (@pxref{Invoking guix-daemon,
2073 @option{--cache-failures}}).
2075 @item --clear-failures
2076 Remove the specified store items from the failed-build cache.
2078 Again, this option only makes sense when the daemon is started with
2079 @option{--cache-failures}. Otherwise, it does nothing.
2082 Show the list of dead files and directories still present in the
2083 store---i.e., files and directories no longer reachable from any root.
2086 Show the list of live store files and directories.
2090 In addition, the references among existing store files can be queried:
2096 List the references (respectively, the referrers) of store files given
2102 List the requisites of the store files passed as arguments. Requisites
2103 include the store files themselves, their references, and the references
2104 of these, recursively. In other words, the returned list is the
2105 @dfn{transitive closure} of the store files.
2107 @xref{Invoking guix size}, for a tool to profile the size of the closure
2108 of an element. @xref{Invoking guix graph}, for a tool to visualize
2109 the graph of references.
2113 Lastly, the following options allow you to check the integrity of the
2114 store and to control disk usage.
2118 @item --verify[=@var{options}]
2119 @cindex integrity, of the store
2120 @cindex integrity checking
2121 Verify the integrity of the store.
2123 By default, make sure that all the store items marked as valid in the
2124 database of the daemon actually exist in @file{/gnu/store}.
2126 When provided, @var{options} must be a comma-separated list containing one
2127 or more of @code{contents} and @code{repair}.
2129 When passing @option{--verify=contents}, the daemon computes the
2130 content hash of each store item and compares it against its hash in the
2131 database. Hash mismatches are reported as data corruptions. Because it
2132 traverses @emph{all the files in the store}, this command can take a
2133 long time, especially on systems with a slow disk drive.
2135 @cindex repairing the store
2136 Using @option{--verify=repair} or @option{--verify=contents,repair}
2137 causes the daemon to try to repair corrupt store items by fetching
2138 substitutes for them (@pxref{Substitutes}). Because repairing is not
2139 atomic, and thus potentially dangerous, it is available only to the
2140 system administrator.
2143 @cindex deduplication
2144 Optimize the store by hard-linking identical files---this is
2145 @dfn{deduplication}.
2147 The daemon performs deduplication after each successful build or archive
2148 import, unless it was started with @code{--disable-deduplication}
2149 (@pxref{Invoking guix-daemon, @code{--disable-deduplication}}). Thus,
2150 this option is primarily useful when the daemon was running with
2151 @code{--disable-deduplication}.
2155 @node Invoking guix pull
2156 @section Invoking @command{guix pull}
2158 Packages are installed or upgraded to the latest version available in
2159 the distribution currently available on your local machine. To update
2160 that distribution, along with the Guix tools, you must run @command{guix
2161 pull}: the command downloads the latest Guix source code and package
2162 descriptions, and deploys it.
2164 On completion, @command{guix package} will use packages and package
2165 versions from this just-retrieved copy of Guix. Not only that, but all
2166 the Guix commands and Scheme modules will also be taken from that latest
2167 version. New @command{guix} sub-commands added by the update also
2170 Any user can update their Guix copy using @command{guix pull}, and the
2171 effect is limited to the user who run @command{guix pull}. For
2172 instance, when user @code{root} runs @command{guix pull}, this has no
2173 effect on the version of Guix that user @code{alice} sees, and vice
2174 versa@footnote{Under the hood, @command{guix pull} updates the
2175 @file{~/.config/guix/latest} symbolic link to point to the latest Guix,
2176 and the @command{guix} command loads code from there.}.
2178 The @command{guix pull} command is usually invoked with no arguments,
2179 but it supports the following options:
2183 Produce verbose output, writing build logs to the standard error output.
2185 @item --url=@var{url}
2186 Download the source tarball of Guix from @var{url}.
2188 By default, the tarball is taken from its canonical address at
2189 @code{gnu.org}, for the stable branch of Guix.
2192 Use the bootstrap Guile to build the latest Guix. This option is only
2193 useful to Guix developers.
2197 @node Invoking guix archive
2198 @section Invoking @command{guix archive}
2200 The @command{guix archive} command allows users to @dfn{export} files
2201 from the store into a single archive, and to later @dfn{import} them.
2202 In particular, it allows store files to be transferred from one machine
2203 to the store on another machine.
2205 To export store files as an archive to standard output, run:
2208 guix archive --export @var{options} @var{specifications}...
2211 @var{specifications} may be either store file names or package
2212 specifications, as for @command{guix package} (@pxref{Invoking guix
2213 package}). For instance, the following command creates an archive
2214 containing the @code{gui} output of the @code{git} package and the main
2215 output of @code{emacs}:
2218 guix archive --export git:gui /gnu/store/...-emacs-24.3 > great.nar
2221 If the specified packages are not built yet, @command{guix archive}
2222 automatically builds them. The build process may be controlled with the
2223 common build options (@pxref{Common Build Options}).
2225 To transfer the @code{emacs} package to a machine connected over SSH,
2229 guix archive --export -r emacs | ssh the-machine guix archive --import
2233 Similarly, a complete user profile may be transferred from one machine
2234 to another like this:
2237 guix archive --export -r $(readlink -f ~/.guix-profile) | \
2238 ssh the-machine guix-archive --import
2242 However, note that, in both examples, all of @code{emacs} and the
2243 profile as well as all of their dependencies are transferred (due to
2244 @code{-r}), regardless of what is already available in the store on the
2245 target machine. The @code{--missing} option can help figure out which
2246 items are missing from the target store.
2248 Archives are stored in the ``Nix archive'' or ``Nar'' format, which is
2249 comparable in spirit to `tar', but with a few noteworthy differences
2250 that make it more appropriate for our purposes. First, rather than
2251 recording all Unix metadata for each file, the Nar format only mentions
2252 the file type (regular, directory, or symbolic link); Unix permissions
2253 and owner/group are dismissed. Second, the order in which directory
2254 entries are stored always follows the order of file names according to
2255 the C locale collation order. This makes archive production fully
2258 When exporting, the daemon digitally signs the contents of the archive,
2259 and that digital signature is appended. When importing, the daemon
2260 verifies the signature and rejects the import in case of an invalid
2261 signature or if the signing key is not authorized.
2262 @c FIXME: Add xref to daemon doc about signatures.
2264 The main options are:
2268 Export the specified store files or packages (see below.) Write the
2269 resulting archive to the standard output.
2271 Dependencies are @emph{not} included in the output, unless
2272 @code{--recursive} is passed.
2276 When combined with @code{--export}, this instructs @command{guix
2277 archive} to include dependencies of the given items in the archive.
2278 Thus, the resulting archive is self-contained: it contains the closure
2279 of the exported store items.
2282 Read an archive from the standard input, and import the files listed
2283 therein into the store. Abort if the archive has an invalid digital
2284 signature, or if it is signed by a public key not among the authorized
2285 keys (see @code{--authorize} below.)
2288 Read a list of store file names from the standard input, one per line,
2289 and write on the standard output the subset of these files missing from
2292 @item --generate-key[=@var{parameters}]
2293 @cindex signing, archives
2294 Generate a new key pair for the daemon. This is a prerequisite before
2295 archives can be exported with @code{--export}. Note that this operation
2296 usually takes time, because it needs to gather enough entropy to
2297 generate the key pair.
2299 The generated key pair is typically stored under @file{/etc/guix}, in
2300 @file{signing-key.pub} (public key) and @file{signing-key.sec} (private
2301 key, which must be kept secret.) When @var{parameters} is omitted,
2302 an ECDSA key using the Ed25519 curve is generated, or, for Libgcrypt
2303 versions before 1.6.0, it is a 4096-bit RSA key.
2304 Alternatively, @var{parameters} can specify
2305 @code{genkey} parameters suitable for Libgcrypt (@pxref{General
2306 public-key related Functions, @code{gcry_pk_genkey},, gcrypt, The
2307 Libgcrypt Reference Manual}).
2310 @cindex authorizing, archives
2311 Authorize imports signed by the public key passed on standard input.
2312 The public key must be in ``s-expression advanced format''---i.e., the
2313 same format as the @file{signing-key.pub} file.
2315 The list of authorized keys is kept in the human-editable file
2316 @file{/etc/guix/acl}. The file contains
2317 @url{http://people.csail.mit.edu/rivest/Sexp.txt, ``advanced-format
2318 s-expressions''} and is structured as an access-control list in the
2319 @url{http://theworld.com/~cme/spki.txt, Simple Public-Key Infrastructure
2322 @item --extract=@var{directory}
2323 @itemx -x @var{directory}
2324 Read a single-item archive as served by substitute servers
2325 (@pxref{Substitutes}) and extract it to @var{directory}. This is a
2326 low-level operation needed in only very narrow use cases; see below.
2328 For example, the following command extracts the substitute for Emacs
2329 served by @code{hydra.gnu.org} to @file{/tmp/emacs}:
2333 https://hydra.gnu.org/nar/@dots{}-emacs-24.5 \
2334 | bunzip2 | guix archive -x /tmp/emacs
2337 Single-item archives are different from multiple-item archives produced
2338 by @command{guix archive --export}; they contain a single store item,
2339 and they do @emph{not} embed a signature. Thus this operation does
2340 @emph{no} signature verification and its output should be considered
2343 The primary purpose of this operation is to facilitate inspection of
2344 archive contents coming from possibly untrusted substitute servers.
2348 @c *********************************************************************
2351 @c *********************************************************************
2352 @node Programming Interface
2353 @chapter Programming Interface
2355 GNU Guix provides several Scheme programming interfaces (APIs) to
2356 define, build, and query packages. The first interface allows users to
2357 write high-level package definitions. These definitions refer to
2358 familiar packaging concepts, such as the name and version of a package,
2359 its build system, and its dependencies. These definitions can then be
2360 turned into concrete build actions.
2362 Build actions are performed by the Guix daemon, on behalf of users. In a
2363 standard setup, the daemon has write access to the store---the
2364 @file{/gnu/store} directory---whereas users do not. The recommended
2365 setup also has the daemon perform builds in chroots, under a specific
2366 build users, to minimize interference with the rest of the system.
2369 Lower-level APIs are available to interact with the daemon and the
2370 store. To instruct the daemon to perform a build action, users actually
2371 provide it with a @dfn{derivation}. A derivation is a low-level
2372 representation of the build actions to be taken, and the environment in
2373 which they should occur---derivations are to package definitions what
2374 assembly is to C programs. The term ``derivation'' comes from the fact
2375 that build results @emph{derive} from them.
2377 This chapter describes all these APIs in turn, starting from high-level
2378 package definitions.
2381 * Defining Packages:: Defining new packages.
2382 * Build Systems:: Specifying how packages are built.
2383 * The Store:: Manipulating the package store.
2384 * Derivations:: Low-level interface to package derivations.
2385 * The Store Monad:: Purely functional interface to the store.
2386 * G-Expressions:: Manipulating build expressions.
2389 @node Defining Packages
2390 @section Defining Packages
2392 The high-level interface to package definitions is implemented in the
2393 @code{(guix packages)} and @code{(guix build-system)} modules. As an
2394 example, the package definition, or @dfn{recipe}, for the GNU Hello
2395 package looks like this:
2398 (define-module (gnu packages hello)
2399 #:use-module (guix packages)
2400 #:use-module (guix download)
2401 #:use-module (guix build-system gnu)
2402 #:use-module (guix licenses)
2403 #:use-module (gnu packages gawk))
2405 (define-public hello
2411 (uri (string-append "mirror://gnu/hello/hello-" version
2415 "0ssi1wpaf7plaswqqjwigppsg5fyh99vdlb9kzl7c9lng89ndq1i"))))
2416 (build-system gnu-build-system)
2417 (arguments '(#:configure-flags '("--enable-silent-rules")))
2418 (inputs `(("gawk" ,gawk)))
2419 (synopsis "Hello, GNU world: An example GNU package")
2420 (description "Guess what GNU Hello prints!")
2421 (home-page "http://www.gnu.org/software/hello/")
2426 Without being a Scheme expert, the reader may have guessed the meaning
2427 of the various fields here. This expression binds the variable
2428 @code{hello} to a @code{<package>} object, which is essentially a record
2429 (@pxref{SRFI-9, Scheme records,, guile, GNU Guile Reference Manual}).
2430 This package object can be inspected using procedures found in the
2431 @code{(guix packages)} module; for instance, @code{(package-name hello)}
2432 returns---surprise!---@code{"hello"}.
2434 With luck, you may be able to import part or all of the definition of
2435 the package you are interested in from another repository, using the
2436 @code{guix import} command (@pxref{Invoking guix import}).
2438 In the example above, @var{hello} is defined in a module of its own,
2439 @code{(gnu packages hello)}. Technically, this is not strictly
2440 necessary, but it is convenient to do so: all the packages defined in
2441 modules under @code{(gnu packages @dots{})} are automatically known to
2442 the command-line tools (@pxref{Package Modules}).
2444 There are a few points worth noting in the above package definition:
2448 The @code{source} field of the package is an @code{<origin>} object
2449 (@pxref{origin Reference}, for the complete reference).
2450 Here, the @code{url-fetch} method from @code{(guix download)} is used,
2451 meaning that the source is a file to be downloaded over FTP or HTTP.
2453 The @code{mirror://gnu} prefix instructs @code{url-fetch} to use one of
2454 the GNU mirrors defined in @code{(guix download)}.
2456 The @code{sha256} field specifies the expected SHA256 hash of the file
2457 being downloaded. It is mandatory, and allows Guix to check the
2458 integrity of the file. The @code{(base32 @dots{})} form introduces the
2459 base32 representation of the hash. You can obtain this information with
2460 @code{guix download} (@pxref{Invoking guix download}) and @code{guix
2461 hash} (@pxref{Invoking guix hash}).
2464 When needed, the @code{origin} form can also have a @code{patches} field
2465 listing patches to be applied, and a @code{snippet} field giving a
2466 Scheme expression to modify the source code.
2469 @cindex GNU Build System
2470 The @code{build-system} field specifies the procedure to build the
2471 package (@pxref{Build Systems}). Here, @var{gnu-build-system}
2472 represents the familiar GNU Build System, where packages may be
2473 configured, built, and installed with the usual @code{./configure &&
2474 make && make check && make install} command sequence.
2477 The @code{arguments} field specifies options for the build system
2478 (@pxref{Build Systems}). Here it is interpreted by
2479 @var{gnu-build-system} as a request run @file{configure} with the
2480 @code{--enable-silent-rules} flag.
2486 What about these quote (@code{'}) characters? They are Scheme syntax to
2487 introduce a literal list; @code{'} is synonymous with @code{quote}.
2488 @xref{Expression Syntax, quoting,, guile, GNU Guile Reference Manual},
2489 for details. Here the value of the @code{arguments} field is a list of
2490 arguments passed to the build system down the road, as with @code{apply}
2491 (@pxref{Fly Evaluation, @code{apply},, guile, GNU Guile Reference
2494 The hash-colon (@code{#:}) sequence defines a Scheme @dfn{keyword}
2495 (@pxref{Keywords,,, guile, GNU Guile Reference Manual}), and
2496 @code{#:configure-flags} is a keyword used to pass a keyword argument
2497 to the build system (@pxref{Coding With Keywords,,, guile, GNU Guile
2501 The @code{inputs} field specifies inputs to the build process---i.e.,
2502 build-time or run-time dependencies of the package. Here, we define an
2503 input called @code{"gawk"} whose value is that of the @var{gawk}
2504 variable; @var{gawk} is itself bound to a @code{<package>} object.
2506 @cindex backquote (quasiquote)
2509 @cindex comma (unquote)
2513 @findex unquote-splicing
2514 Again, @code{`} (a backquote, synonymous with @code{quasiquote}) allows
2515 us to introduce a literal list in the @code{inputs} field, while
2516 @code{,} (a comma, synonymous with @code{unquote}) allows us to insert a
2517 value in that list (@pxref{Expression Syntax, unquote,, guile, GNU Guile
2520 Note that GCC, Coreutils, Bash, and other essential tools do not need to
2521 be specified as inputs here. Instead, @var{gnu-build-system} takes care
2522 of ensuring that they are present (@pxref{Build Systems}).
2524 However, any other dependencies need to be specified in the
2525 @code{inputs} field. Any dependency not specified here will simply be
2526 unavailable to the build process, possibly leading to a build failure.
2529 @xref{package Reference}, for a full description of possible fields.
2531 Once a package definition is in place, the
2532 package may actually be built using the @code{guix build} command-line
2533 tool (@pxref{Invoking guix build}). You can easily jump back to the
2534 package definition using the @command{guix edit} command
2535 (@pxref{Invoking guix edit}).
2536 @xref{Packaging Guidelines}, for
2537 more information on how to test package definitions, and
2538 @ref{Invoking guix lint}, for information on how to check a definition
2539 for style conformance.
2541 Finally, updating the package definition to a new upstream version
2542 can be partly automated by the @command{guix refresh} command
2543 (@pxref{Invoking guix refresh}).
2545 Behind the scenes, a derivation corresponding to the @code{<package>}
2546 object is first computed by the @code{package-derivation} procedure.
2547 That derivation is stored in a @code{.drv} file under @file{/gnu/store}.
2548 The build actions it prescribes may then be realized by using the
2549 @code{build-derivations} procedure (@pxref{The Store}).
2551 @deffn {Scheme Procedure} package-derivation @var{store} @var{package} [@var{system}]
2552 Return the @code{<derivation>} object of @var{package} for @var{system}
2553 (@pxref{Derivations}).
2555 @var{package} must be a valid @code{<package>} object, and @var{system}
2556 must be a string denoting the target system type---e.g.,
2557 @code{"x86_64-linux"} for an x86_64 Linux-based GNU system. @var{store}
2558 must be a connection to the daemon, which operates on the store
2559 (@pxref{The Store}).
2563 @cindex cross-compilation
2564 Similarly, it is possible to compute a derivation that cross-builds a
2565 package for some other system:
2567 @deffn {Scheme Procedure} package-cross-derivation @var{store} @
2568 @var{package} @var{target} [@var{system}]
2569 Return the @code{<derivation>} object of @var{package} cross-built from
2570 @var{system} to @var{target}.
2572 @var{target} must be a valid GNU triplet denoting the target hardware
2573 and operating system, such as @code{"mips64el-linux-gnu"}
2574 (@pxref{Configuration Names, GNU configuration triplets,, configure, GNU
2575 Configure and Build System}).
2578 @cindex package transformations
2579 @cindex input rewriting
2580 @cindex dependency tree rewriting
2581 Packages can be manipulated in arbitrary ways. An example of a useful
2582 transformation is @dfn{input rewriting}, whereby the dependency tree of
2583 a package is rewritten by replacing specific inputs by others:
2585 @deffn {Scheme Procedure} package-input-rewriting @var{replacements} @
2586 [@var{rewrite-name}]
2587 Return a procedure that, when passed a package, replaces its direct and
2588 indirect dependencies (but not its implicit inputs) according to
2589 @var{replacements}. @var{replacements} is a list of package pairs; the
2590 first element of each pair is the package to replace, and the second one
2593 Optionally, @var{rewrite-name} is a one-argument procedure that takes
2594 the name of a package and returns its new name after rewrite.
2598 Consider this example:
2601 (define libressl-instead-of-openssl
2602 ;; This is a procedure to replace OPENSSL by LIBRESSL,
2604 (package-input-rewriting `((,openssl . ,libressl))))
2606 (define git-with-libressl
2607 (libressl-instead-of-openssl git))
2611 Here we first define a rewriting procedure that replaces @var{openssl}
2612 with @var{libressl}. Then we use it to define a @dfn{variant} of the
2613 @var{git} package that uses @var{libressl} instead of @var{openssl}.
2614 This is exactly what the @option{--with-input} command-line option does
2615 (@pxref{Package Transformation Options, @option{--with-input}}).
2618 * package Reference :: The package data type.
2619 * origin Reference:: The origin data type.
2623 @node package Reference
2624 @subsection @code{package} Reference
2626 This section summarizes all the options available in @code{package}
2627 declarations (@pxref{Defining Packages}).
2629 @deftp {Data Type} package
2630 This is the data type representing a package recipe.
2634 The name of the package, as a string.
2636 @item @code{version}
2637 The version of the package, as a string.
2640 An object telling how the source code for the package should be
2641 acquired. Most of the time, this is an @code{origin} object, which
2642 denotes a file fetched from the Internet (@pxref{origin Reference}). It
2643 can also be any other ``file-like'' object such as a @code{local-file},
2644 which denotes a file from the local file system (@pxref{G-Expressions,
2645 @code{local-file}}).
2647 @item @code{build-system}
2648 The build system that should be used to build the package (@pxref{Build
2651 @item @code{arguments} (default: @code{'()})
2652 The arguments that should be passed to the build system. This is a
2653 list, typically containing sequential keyword-value pairs.
2655 @item @code{inputs} (default: @code{'()})
2656 @itemx @code{native-inputs} (default: @code{'()})
2657 @itemx @code{propagated-inputs} (default: @code{'()})
2658 @cindex inputs, of packages
2659 These fields list dependencies of the package. Each one is a list of
2660 tuples, where each tuple has a label for the input (a string) as its
2661 first element, a package, origin, or derivation as its second element,
2662 and optionally the name of the output thereof that should be used, which
2663 defaults to @code{"out"} (@pxref{Packages with Multiple Outputs}, for
2664 more on package outputs). For example, the list below specifies three
2668 `(("libffi" ,libffi)
2669 ("libunistring" ,libunistring)
2670 ("glib:bin" ,glib "bin")) ;the "bin" output of Glib
2673 @cindex cross compilation, package dependencies
2674 The distinction between @code{native-inputs} and @code{inputs} is
2675 necessary when considering cross-compilation. When cross-compiling,
2676 dependencies listed in @code{inputs} are built for the @emph{target}
2677 architecture; conversely, dependencies listed in @code{native-inputs}
2678 are built for the architecture of the @emph{build} machine.
2680 @code{native-inputs} is typically used to list tools needed at
2681 build time, but not at run time, such as Autoconf, Automake, pkg-config,
2682 Gettext, or Bison. @command{guix lint} can report likely mistakes in
2683 this area (@pxref{Invoking guix lint}).
2685 @anchor{package-propagated-inputs}
2686 Lastly, @code{propagated-inputs} is similar to @code{inputs}, but the
2687 specified packages will be automatically installed alongside the package
2688 they belong to (@pxref{package-cmd-propagated-inputs, @command{guix
2689 package}}, for information on how @command{guix package} deals with
2692 For example this is necessary when a C/C++ library needs headers of
2693 another library to compile, or when a pkg-config file refers to another
2694 one @i{via} its @code{Requires} field.
2696 Another example where @code{propagated-inputs} is useful is for languages
2697 that lack a facility to record the run-time search path akin to the
2698 @code{RUNPATH} of ELF files; this includes Guile, Python, Perl, GHC, and
2699 more. To ensure that libraries written in those languages can find
2700 library code they depend on at run time, run-time dependencies must be
2701 listed in @code{propagated-inputs} rather than @code{inputs}.
2703 @item @code{self-native-input?} (default: @code{#f})
2704 This is a Boolean field telling whether the package should use itself as
2705 a native input when cross-compiling.
2707 @item @code{outputs} (default: @code{'("out")})
2708 The list of output names of the package. @xref{Packages with Multiple
2709 Outputs}, for typical uses of additional outputs.
2711 @item @code{native-search-paths} (default: @code{'()})
2712 @itemx @code{search-paths} (default: @code{'()})
2713 A list of @code{search-path-specification} objects describing
2714 search-path environment variables honored by the package.
2716 @item @code{replacement} (default: @code{#f})
2717 This must be either @code{#f} or a package object that will be used as a
2718 @dfn{replacement} for this package. @xref{Security Updates, grafts},
2721 @item @code{synopsis}
2722 A one-line description of the package.
2724 @item @code{description}
2725 A more elaborate description of the package.
2727 @item @code{license}
2728 The license of the package; a value from @code{(guix licenses)},
2729 or a list of such values.
2731 @item @code{home-page}
2732 The URL to the home-page of the package, as a string.
2734 @item @code{supported-systems} (default: @var{%supported-systems})
2735 The list of systems supported by the package, as strings of the form
2736 @code{architecture-kernel}, for example @code{"x86_64-linux"}.
2738 @item @code{maintainers} (default: @code{'()})
2739 The list of maintainers of the package, as @code{maintainer} objects.
2741 @item @code{location} (default: source location of the @code{package} form)
2742 The source location of the package. It is useful to override this when
2743 inheriting from another package, in which case this field is not
2744 automatically corrected.
2749 @node origin Reference
2750 @subsection @code{origin} Reference
2752 This section summarizes all the options available in @code{origin}
2753 declarations (@pxref{Defining Packages}).
2755 @deftp {Data Type} origin
2756 This is the data type representing a source code origin.
2760 An object containing the URI of the source. The object type depends on
2761 the @code{method} (see below). For example, when using the
2762 @var{url-fetch} method of @code{(guix download)}, the valid @code{uri}
2763 values are: a URL represented as a string, or a list thereof.
2766 A procedure that handles the URI.
2771 @item @var{url-fetch} from @code{(guix download)}
2772 download a file from the HTTP, HTTPS, or FTP URL specified in the
2776 @item @var{git-fetch} from @code{(guix git-download)}
2777 clone the Git version control repository, and check out the revision
2778 specified in the @code{uri} field as a @code{git-reference} object; a
2779 @code{git-reference} looks like this:
2783 (url "git://git.debian.org/git/pkg-shadow/shadow")
2784 (commit "v4.1.5.1"))
2789 A bytevector containing the SHA-256 hash of the source. Typically the
2790 @code{base32} form is used here to generate the bytevector from a
2793 You can obtain this information using @code{guix download}
2794 (@pxref{Invoking guix download}) or @code{guix hash} (@pxref{Invoking
2797 @item @code{file-name} (default: @code{#f})
2798 The file name under which the source code should be saved. When this is
2799 @code{#f}, a sensible default value will be used in most cases. In case
2800 the source is fetched from a URL, the file name from the URL will be
2801 used. For version control checkouts, it is recommended to provide the
2802 file name explicitly because the default is not very descriptive.
2804 @item @code{patches} (default: @code{'()})
2805 A list of file names containing patches to be applied to the source.
2807 @item @code{snippet} (default: @code{#f})
2808 A G-expression (@pxref{G-Expressions}) or S-expression that will be run
2809 in the source directory. This is a convenient way to modify the source,
2810 sometimes more convenient than a patch.
2812 @item @code{patch-flags} (default: @code{'("-p1")})
2813 A list of command-line flags that should be passed to the @code{patch}
2816 @item @code{patch-inputs} (default: @code{#f})
2817 Input packages or derivations to the patching process. When this is
2818 @code{#f}, the usual set of inputs necessary for patching are provided,
2819 such as GNU@tie{}Patch.
2821 @item @code{modules} (default: @code{'()})
2822 A list of Guile modules that should be loaded during the patching
2823 process and while running the code in the @code{snippet} field.
2825 @item @code{patch-guile} (default: @code{#f})
2826 The Guile package that should be used in the patching process. When
2827 this is @code{#f}, a sensible default is used.
2833 @section Build Systems
2835 @cindex build system
2836 Each package definition specifies a @dfn{build system} and arguments for
2837 that build system (@pxref{Defining Packages}). This @code{build-system}
2838 field represents the build procedure of the package, as well as implicit
2839 dependencies of that build procedure.
2841 Build systems are @code{<build-system>} objects. The interface to
2842 create and manipulate them is provided by the @code{(guix build-system)}
2843 module, and actual build systems are exported by specific modules.
2845 @cindex bag (low-level package representation)
2846 Under the hood, build systems first compile package objects to
2847 @dfn{bags}. A @dfn{bag} is like a package, but with less
2848 ornamentation---in other words, a bag is a lower-level representation of
2849 a package, which includes all the inputs of that package, including some
2850 that were implicitly added by the build system. This intermediate
2851 representation is then compiled to a derivation (@pxref{Derivations}).
2853 Build systems accept an optional list of @dfn{arguments}. In package
2854 definitions, these are passed @i{via} the @code{arguments} field
2855 (@pxref{Defining Packages}). They are typically keyword arguments
2856 (@pxref{Optional Arguments, keyword arguments in Guile,, guile, GNU
2857 Guile Reference Manual}). The value of these arguments is usually
2858 evaluated in the @dfn{build stratum}---i.e., by a Guile process launched
2859 by the daemon (@pxref{Derivations}).
2861 The main build system is @var{gnu-build-system}, which implements the
2862 standard build procedure for GNU and many other packages. It
2863 is provided by the @code{(guix build-system gnu)} module.
2865 @defvr {Scheme Variable} gnu-build-system
2866 @var{gnu-build-system} represents the GNU Build System, and variants
2867 thereof (@pxref{Configuration, configuration and makefile conventions,,
2868 standards, GNU Coding Standards}).
2870 @cindex build phases
2871 In a nutshell, packages using it are configured, built, and installed with
2872 the usual @code{./configure && make && make check && make install}
2873 command sequence. In practice, a few additional steps are often needed.
2874 All these steps are split up in separate @dfn{phases},
2875 notably@footnote{Please see the @code{(guix build gnu-build-system)}
2876 modules for more details about the build phases.}:
2880 Unpack the source tarball, and change the current directory to the
2881 extracted source tree. If the source is actually a directory, copy it
2882 to the build tree, and enter that directory.
2884 @item patch-source-shebangs
2885 Patch shebangs encountered in source files so they refer to the right
2886 store file names. For instance, this changes @code{#!/bin/sh} to
2887 @code{#!/gnu/store/@dots{}-bash-4.3/bin/sh}.
2890 Run the @file{configure} script with a number of default options, such
2891 as @code{--prefix=/gnu/store/@dots{}}, as well as the options specified
2892 by the @code{#:configure-flags} argument.
2895 Run @code{make} with the list of flags specified with
2896 @code{#:make-flags}. If the @code{#:parallel-build?} argument is true
2897 (the default), build with @code{make -j}.
2900 Run @code{make check}, or some other target specified with
2901 @code{#:test-target}, unless @code{#:tests? #f} is passed. If the
2902 @code{#:parallel-tests?} argument is true (the default), run @code{make
2906 Run @code{make install} with the flags listed in @code{#:make-flags}.
2908 @item patch-shebangs
2909 Patch shebangs on the installed executable files.
2912 Strip debugging symbols from ELF files (unless @code{#:strip-binaries?}
2913 is false), copying them to the @code{debug} output when available
2914 (@pxref{Installing Debugging Files}).
2917 @vindex %standard-phases
2918 The build-side module @code{(guix build gnu-build-system)} defines
2919 @var{%standard-phases} as the default list of build phases.
2920 @var{%standard-phases} is a list of symbol/procedure pairs, where the
2921 procedure implements the actual phase.
2923 The list of phases used for a particular package can be changed with the
2924 @code{#:phases} parameter. For instance, passing:
2927 #:phases (modify-phases %standard-phases (delete 'configure))
2930 means that all the phases described above will be used, except the
2931 @code{configure} phase.
2933 In addition, this build system ensures that the ``standard'' environment
2934 for GNU packages is available. This includes tools such as GCC, libc,
2935 Coreutils, Bash, Make, Diffutils, grep, and sed (see the @code{(guix
2936 build-system gnu)} module for a complete list). We call these the
2937 @dfn{implicit inputs} of a package, because package definitions do not
2938 have to mention them.
2941 Other @code{<build-system>} objects are defined to support other
2942 conventions and tools used by free software packages. They inherit most
2943 of @var{gnu-build-system}, and differ mainly in the set of inputs
2944 implicitly added to the build process, and in the list of phases
2945 executed. Some of these build systems are listed below.
2947 @defvr {Scheme Variable} ant-build-system
2948 This variable is exported by @code{(guix build-system ant)}. It
2949 implements the build procedure for Java packages that can be built with
2950 @url{http://ant.apache.org/, Ant build tool}.
2952 It adds both @code{ant} and the @dfn{Java Development Kit} (JDK) as
2953 provided by the @code{icedtea} package to the set of inputs. Different
2954 packages can be specified with the @code{#:ant} and @code{#:jdk}
2955 parameters, respectively.
2957 When the original package does not provide a suitable Ant build file,
2958 the parameter @code{#:jar-name} can be used to generate a minimal Ant
2959 build file @file{build.xml} with tasks to build the specified jar
2962 The parameter @code{#:build-target} can be used to specify the Ant task
2963 that should be run during the @code{build} phase. By default the
2964 ``jar'' task will be run.
2968 @defvr {Scheme Variable} cmake-build-system
2969 This variable is exported by @code{(guix build-system cmake)}. It
2970 implements the build procedure for packages using the
2971 @url{http://www.cmake.org, CMake build tool}.
2973 It automatically adds the @code{cmake} package to the set of inputs.
2974 Which package is used can be specified with the @code{#:cmake}
2977 The @code{#:configure-flags} parameter is taken as a list of flags
2978 passed to the @command{cmake} command. The @code{#:build-type}
2979 parameter specifies in abstract terms the flags passed to the compiler;
2980 it defaults to @code{"RelWithDebInfo"} (short for ``release mode with
2981 debugging information''), which roughly means that code is compiled with
2982 @code{-O2 -g}, as is the case for Autoconf-based packages by default.
2985 @defvr {Scheme Variable} glib-or-gtk-build-system
2986 This variable is exported by @code{(guix build-system glib-or-gtk)}. It
2987 is intended for use with packages making use of GLib or GTK+.
2989 This build system adds the following two phases to the ones defined by
2990 @var{gnu-build-system}:
2993 @item glib-or-gtk-wrap
2994 The phase @code{glib-or-gtk-wrap} ensures that programs in
2995 @file{bin/} are able to find GLib ``schemas'' and
2996 @uref{https://developer.gnome.org/gtk3/stable/gtk-running.html, GTK+
2997 modules}. This is achieved by wrapping the programs in launch scripts
2998 that appropriately set the @code{XDG_DATA_DIRS} and @code{GTK_PATH}
2999 environment variables.
3001 It is possible to exclude specific package outputs from that wrapping
3002 process by listing their names in the
3003 @code{#:glib-or-gtk-wrap-excluded-outputs} parameter. This is useful
3004 when an output is known not to contain any GLib or GTK+ binaries, and
3005 where wrapping would gratuitously add a dependency of that output on
3008 @item glib-or-gtk-compile-schemas
3009 The phase @code{glib-or-gtk-compile-schemas} makes sure that all
3010 @uref{https://developer.gnome.org/gio/stable/glib-compile-schemas.html,
3011 GSettings schemas} of GLib are compiled. Compilation is performed by the
3012 @command{glib-compile-schemas} program. It is provided by the package
3013 @code{glib:bin} which is automatically imported by the build system.
3014 The @code{glib} package providing @command{glib-compile-schemas} can be
3015 specified with the @code{#:glib} parameter.
3018 Both phases are executed after the @code{install} phase.
3021 @defvr {Scheme Variable} python-build-system
3022 This variable is exported by @code{(guix build-system python)}. It
3023 implements the more or less standard build procedure used by Python
3024 packages, which consists in running @code{python setup.py build} and
3025 then @code{python setup.py install --prefix=/gnu/store/@dots{}}.
3027 For packages that install stand-alone Python programs under @code{bin/},
3028 it takes care of wrapping these programs so that their @code{PYTHONPATH}
3029 environment variable points to all the Python libraries they depend on.
3031 Which Python package is used to perform the build can be specified with
3032 the @code{#:python} parameter. This is a useful way to force a package
3033 to be built for a specific version of the Python interpreter, which
3034 might be necessary if the package is only compatible with a single
3035 interpreter version.
3038 @defvr {Scheme Variable} perl-build-system
3039 This variable is exported by @code{(guix build-system perl)}. It
3040 implements the standard build procedure for Perl packages, which either
3041 consists in running @code{perl Build.PL --prefix=/gnu/store/@dots{}},
3042 followed by @code{Build} and @code{Build install}; or in running
3043 @code{perl Makefile.PL PREFIX=/gnu/store/@dots{}}, followed by
3044 @code{make} and @code{make install}, depending on which of
3045 @code{Build.PL} or @code{Makefile.PL} is present in the package
3046 distribution. Preference is given to the former if both @code{Build.PL}
3047 and @code{Makefile.PL} exist in the package distribution. This
3048 preference can be reversed by specifying @code{#t} for the
3049 @code{#:make-maker?} parameter.
3051 The initial @code{perl Makefile.PL} or @code{perl Build.PL} invocation
3052 passes flags specified by the @code{#:make-maker-flags} or
3053 @code{#:module-build-flags} parameter, respectively.
3055 Which Perl package is used can be specified with @code{#:perl}.
3058 @defvr {Scheme Variable} r-build-system
3059 This variable is exported by @code{(guix build-system r)}. It
3060 implements the build procedure used by @uref{http://r-project.org, R}
3061 packages, which essentially is little more than running @code{R CMD
3062 INSTALL --library=/gnu/store/@dots{}} in an environment where
3063 @code{R_LIBS_SITE} contains the paths to all R package inputs. Tests
3064 are run after installation using the R function
3065 @code{tools::testInstalledPackage}.
3068 @defvr {Scheme Variable} ruby-build-system
3069 This variable is exported by @code{(guix build-system ruby)}. It
3070 implements the RubyGems build procedure used by Ruby packages, which
3071 involves running @code{gem build} followed by @code{gem install}.
3073 The @code{source} field of a package that uses this build system
3074 typically references a gem archive, since this is the format that Ruby
3075 developers use when releasing their software. The build system unpacks
3076 the gem archive, potentially patches the source, runs the test suite,
3077 repackages the gem, and installs it. Additionally, directories and
3078 tarballs may be referenced to allow building unreleased gems from Git or
3079 a traditional source release tarball.
3081 Which Ruby package is used can be specified with the @code{#:ruby}
3082 parameter. A list of additional flags to be passed to the @command{gem}
3083 command can be specified with the @code{#:gem-flags} parameter.
3086 @defvr {Scheme Variable} waf-build-system
3087 This variable is exported by @code{(guix build-system waf)}. It
3088 implements a build procedure around the @code{waf} script. The common
3089 phases---@code{configure}, @code{build}, and @code{install}---are
3090 implemented by passing their names as arguments to the @code{waf}
3093 The @code{waf} script is executed by the Python interpreter. Which
3094 Python package is used to run the script can be specified with the
3095 @code{#:python} parameter.
3098 @defvr {Scheme Variable} haskell-build-system
3099 This variable is exported by @code{(guix build-system haskell)}. It
3100 implements the Cabal build procedure used by Haskell packages, which
3101 involves running @code{runhaskell Setup.hs configure
3102 --prefix=/gnu/store/@dots{}} and @code{runhaskell Setup.hs build}.
3103 Instead of installing the package by running @code{runhaskell Setup.hs
3104 install}, to avoid trying to register libraries in the read-only
3105 compiler store directory, the build system uses @code{runhaskell
3106 Setup.hs copy}, followed by @code{runhaskell Setup.hs register}. In
3107 addition, the build system generates the package documentation by
3108 running @code{runhaskell Setup.hs haddock}, unless @code{#:haddock? #f}
3109 is passed. Optional Haddock parameters can be passed with the help of
3110 the @code{#:haddock-flags} parameter. If the file @code{Setup.hs} is
3111 not found, the build system looks for @code{Setup.lhs} instead.
3113 Which Haskell compiler is used can be specified with the @code{#:haskell}
3114 parameter which defaults to @code{ghc}.
3117 @defvr {Scheme Variable} emacs-build-system
3118 This variable is exported by @code{(guix build-system emacs)}. It
3119 implements an installation procedure similar to the packaging system
3120 of Emacs itself (@pxref{Packages,,, emacs, The GNU Emacs Manual}).
3122 It first creates the @code{@var{package}-autoloads.el} file, then it
3123 byte compiles all Emacs Lisp files. Differently from the Emacs
3124 packaging system, the Info documentation files are moved to the standard
3125 documentation directory and the @file{dir} file is deleted. Each
3126 package is installed in its own directory under
3127 @file{share/emacs/site-lisp/guix.d}.
3130 Lastly, for packages that do not need anything as sophisticated, a
3131 ``trivial'' build system is provided. It is trivial in the sense that
3132 it provides basically no support: it does not pull any implicit inputs,
3133 and does not have a notion of build phases.
3135 @defvr {Scheme Variable} trivial-build-system
3136 This variable is exported by @code{(guix build-system trivial)}.
3138 This build system requires a @code{#:builder} argument. This argument
3139 must be a Scheme expression that builds the package output(s)---as
3140 with @code{build-expression->derivation} (@pxref{Derivations,
3141 @code{build-expression->derivation}}).
3151 Conceptually, the @dfn{store} is the place where derivations that have
3152 been built successfully are stored---by default, @file{/gnu/store}.
3153 Sub-directories in the store are referred to as @dfn{store items} or
3154 sometimes @dfn{store paths}. The store has an associated database that
3155 contains information such as the store paths referred to by each store
3156 path, and the list of @emph{valid} store items---results of successful
3157 builds. This database resides in @file{@var{localstatedir}/guix/db},
3158 where @var{localstatedir} is the state directory specified @i{via}
3159 @option{--localstatedir} at configure time, usually @file{/var}.
3161 The store is @emph{always} accessed by the daemon on behalf of its clients
3162 (@pxref{Invoking guix-daemon}). To manipulate the store, clients
3163 connect to the daemon over a Unix-domain socket, send requests to it,
3164 and read the result---these are remote procedure calls, or RPCs.
3167 Users must @emph{never} modify files under @file{/gnu/store} directly.
3168 This would lead to inconsistencies and break the immutability
3169 assumptions of Guix's functional model (@pxref{Introduction}).
3171 @xref{Invoking guix gc, @command{guix gc --verify}}, for information on
3172 how to check the integrity of the store and attempt recovery from
3173 accidental modifications.
3176 The @code{(guix store)} module provides procedures to connect to the
3177 daemon, and to perform RPCs. These are described below.
3179 @deffn {Scheme Procedure} open-connection [@var{file}] [#:reserve-space? #t]
3180 Connect to the daemon over the Unix-domain socket at @var{file}. When
3181 @var{reserve-space?} is true, instruct it to reserve a little bit of
3182 extra space on the file system so that the garbage collector can still
3183 operate should the disk become full. Return a server object.
3185 @var{file} defaults to @var{%default-socket-path}, which is the normal
3186 location given the options that were passed to @command{configure}.
3189 @deffn {Scheme Procedure} close-connection @var{server}
3190 Close the connection to @var{server}.
3193 @defvr {Scheme Variable} current-build-output-port
3194 This variable is bound to a SRFI-39 parameter, which refers to the port
3195 where build and error logs sent by the daemon should be written.
3198 Procedures that make RPCs all take a server object as their first
3201 @deffn {Scheme Procedure} valid-path? @var{server} @var{path}
3202 @cindex invalid store items
3203 Return @code{#t} when @var{path} designates a valid store item and
3204 @code{#f} otherwise (an invalid item may exist on disk but still be
3205 invalid, for instance because it is the result of an aborted or failed
3208 A @code{&nix-protocol-error} condition is raised if @var{path} is not
3209 prefixed by the store directory (@file{/gnu/store}).
3212 @deffn {Scheme Procedure} add-text-to-store @var{server} @var{name} @var{text} [@var{references}]
3213 Add @var{text} under file @var{name} in the store, and return its store
3214 path. @var{references} is the list of store paths referred to by the
3215 resulting store path.
3218 @deffn {Scheme Procedure} build-derivations @var{server} @var{derivations}
3219 Build @var{derivations} (a list of @code{<derivation>} objects or
3220 derivation paths), and return when the worker is done building them.
3221 Return @code{#t} on success.
3224 Note that the @code{(guix monads)} module provides a monad as well as
3225 monadic versions of the above procedures, with the goal of making it
3226 more convenient to work with code that accesses the store (@pxref{The
3230 @i{This section is currently incomplete.}
3233 @section Derivations
3236 Low-level build actions and the environment in which they are performed
3237 are represented by @dfn{derivations}. A derivation contains the
3238 following pieces of information:
3242 The outputs of the derivation---derivations produce at least one file or
3243 directory in the store, but may produce more.
3246 The inputs of the derivations, which may be other derivations or plain
3247 files in the store (patches, build scripts, etc.)
3250 The system type targeted by the derivation---e.g., @code{x86_64-linux}.
3253 The file name of a build script in the store, along with the arguments
3257 A list of environment variables to be defined.
3261 @cindex derivation path
3262 Derivations allow clients of the daemon to communicate build actions to
3263 the store. They exist in two forms: as an in-memory representation,
3264 both on the client- and daemon-side, and as files in the store whose
3265 name end in @code{.drv}---these files are referred to as @dfn{derivation
3266 paths}. Derivations paths can be passed to the @code{build-derivations}
3267 procedure to perform the build actions they prescribe (@pxref{The
3270 The @code{(guix derivations)} module provides a representation of
3271 derivations as Scheme objects, along with procedures to create and
3272 otherwise manipulate derivations. The lowest-level primitive to create
3273 a derivation is the @code{derivation} procedure:
3275 @deffn {Scheme Procedure} derivation @var{store} @var{name} @var{builder} @
3276 @var{args} [#:outputs '("out")] [#:hash #f] [#:hash-algo #f] @
3277 [#:recursive? #f] [#:inputs '()] [#:env-vars '()] @
3278 [#:system (%current-system)] [#:references-graphs #f] @
3279 [#:allowed-references #f] [#:disallowed-references #f] @
3280 [#:leaked-env-vars #f] [#:local-build? #f] @
3281 [#:substitutable? #t]
3282 Build a derivation with the given arguments, and return the resulting
3283 @code{<derivation>} object.
3285 When @var{hash} and @var{hash-algo} are given, a
3286 @dfn{fixed-output derivation} is created---i.e., one whose result is
3287 known in advance, such as a file download. If, in addition,
3288 @var{recursive?} is true, then that fixed output may be an executable
3289 file or a directory and @var{hash} must be the hash of an archive
3290 containing this output.
3292 When @var{references-graphs} is true, it must be a list of file
3293 name/store path pairs. In that case, the reference graph of each store
3294 path is exported in the build environment in the corresponding file, in
3295 a simple text format.
3297 When @var{allowed-references} is true, it must be a list of store items
3298 or outputs that the derivation's output may refer to. Likewise,
3299 @var{disallowed-references}, if true, must be a list of things the
3300 outputs may @emph{not} refer to.
3302 When @var{leaked-env-vars} is true, it must be a list of strings
3303 denoting environment variables that are allowed to ``leak'' from the
3304 daemon's environment to the build environment. This is only applicable
3305 to fixed-output derivations---i.e., when @var{hash} is true. The main
3306 use is to allow variables such as @code{http_proxy} to be passed to
3307 derivations that download files.
3309 When @var{local-build?} is true, declare that the derivation is not a
3310 good candidate for offloading and should rather be built locally
3311 (@pxref{Daemon Offload Setup}). This is the case for small derivations
3312 where the costs of data transfers would outweigh the benefits.
3314 When @var{substitutable?} is false, declare that substitutes of the
3315 derivation's output should not be used (@pxref{Substitutes}). This is
3316 useful, for instance, when building packages that capture details of the
3317 host CPU instruction set.
3321 Here's an example with a shell script as its builder, assuming
3322 @var{store} is an open connection to the daemon, and @var{bash} points
3323 to a Bash executable in the store:
3326 (use-modules (guix utils)
3330 (let ((builder ; add the Bash script to the store
3331 (add-text-to-store store "my-builder.sh"
3332 "echo hello world > $out\n" '())))
3333 (derivation store "foo"
3334 bash `("-e" ,builder)
3335 #:inputs `((,bash) (,builder))
3336 #:env-vars '(("HOME" . "/homeless"))))
3337 @result{} #<derivation /gnu/store/@dots{}-foo.drv => /gnu/store/@dots{}-foo>
3340 As can be guessed, this primitive is cumbersome to use directly. A
3341 better approach is to write build scripts in Scheme, of course! The
3342 best course of action for that is to write the build code as a
3343 ``G-expression'', and to pass it to @code{gexp->derivation}. For more
3344 information, @pxref{G-Expressions}.
3346 Once upon a time, @code{gexp->derivation} did not exist and constructing
3347 derivations with build code written in Scheme was achieved with
3348 @code{build-expression->derivation}, documented below. This procedure
3349 is now deprecated in favor of the much nicer @code{gexp->derivation}.
3351 @deffn {Scheme Procedure} build-expression->derivation @var{store} @
3352 @var{name} @var{exp} @
3353 [#:system (%current-system)] [#:inputs '()] @
3354 [#:outputs '("out")] [#:hash #f] [#:hash-algo #f] @
3355 [#:recursive? #f] [#:env-vars '()] [#:modules '()] @
3356 [#:references-graphs #f] [#:allowed-references #f] @
3357 [#:disallowed-references #f] @
3358 [#:local-build? #f] [#:substitutable? #t] [#:guile-for-build #f]
3359 Return a derivation that executes Scheme expression @var{exp} as a
3360 builder for derivation @var{name}. @var{inputs} must be a list of
3361 @code{(name drv-path sub-drv)} tuples; when @var{sub-drv} is omitted,
3362 @code{"out"} is assumed. @var{modules} is a list of names of Guile
3363 modules from the current search path to be copied in the store,
3364 compiled, and made available in the load path during the execution of
3365 @var{exp}---e.g., @code{((guix build utils) (guix build
3366 gnu-build-system))}.
3368 @var{exp} is evaluated in an environment where @code{%outputs} is bound
3369 to a list of output/path pairs, and where @code{%build-inputs} is bound
3370 to a list of string/output-path pairs made from @var{inputs}.
3371 Optionally, @var{env-vars} is a list of string pairs specifying the name
3372 and value of environment variables visible to the builder. The builder
3373 terminates by passing the result of @var{exp} to @code{exit}; thus, when
3374 @var{exp} returns @code{#f}, the build is considered to have failed.
3376 @var{exp} is built using @var{guile-for-build} (a derivation). When
3377 @var{guile-for-build} is omitted or is @code{#f}, the value of the
3378 @code{%guile-for-build} fluid is used instead.
3380 See the @code{derivation} procedure for the meaning of
3381 @var{references-graphs}, @var{allowed-references},
3382 @var{disallowed-references}, @var{local-build?}, and
3383 @var{substitutable?}.
3387 Here's an example of a single-output derivation that creates a directory
3388 containing one file:
3391 (let ((builder '(let ((out (assoc-ref %outputs "out")))
3392 (mkdir out) ; create /gnu/store/@dots{}-goo
3393 (call-with-output-file (string-append out "/test")
3395 (display '(hello guix) p))))))
3396 (build-expression->derivation store "goo" builder))
3398 @result{} #<derivation /gnu/store/@dots{}-goo.drv => @dots{}>
3402 @node The Store Monad
3403 @section The Store Monad
3407 The procedures that operate on the store described in the previous
3408 sections all take an open connection to the build daemon as their first
3409 argument. Although the underlying model is functional, they either have
3410 side effects or depend on the current state of the store.
3412 The former is inconvenient: the connection to the build daemon has to be
3413 carried around in all those functions, making it impossible to compose
3414 functions that do not take that parameter with functions that do. The
3415 latter can be problematic: since store operations have side effects
3416 and/or depend on external state, they have to be properly sequenced.
3418 @cindex monadic values
3419 @cindex monadic functions
3420 This is where the @code{(guix monads)} module comes in. This module
3421 provides a framework for working with @dfn{monads}, and a particularly
3422 useful monad for our uses, the @dfn{store monad}. Monads are a
3423 construct that allows two things: associating ``context'' with values
3424 (in our case, the context is the store), and building sequences of
3425 computations (here computations include accesses to the store). Values
3426 in a monad---values that carry this additional context---are called
3427 @dfn{monadic values}; procedures that return such values are called
3428 @dfn{monadic procedures}.
3430 Consider this ``normal'' procedure:
3433 (define (sh-symlink store)
3434 ;; Return a derivation that symlinks the 'bash' executable.
3435 (let* ((drv (package-derivation store bash))
3436 (out (derivation->output-path drv))
3437 (sh (string-append out "/bin/bash")))
3438 (build-expression->derivation store "sh"
3439 `(symlink ,sh %output))))
3442 Using @code{(guix monads)} and @code{(guix gexp)}, it may be rewritten
3443 as a monadic function:
3446 (define (sh-symlink)
3447 ;; Same, but return a monadic value.
3448 (mlet %store-monad ((drv (package->derivation bash)))
3449 (gexp->derivation "sh"
3450 #~(symlink (string-append #$drv "/bin/bash")
3454 There are several things to note in the second version: the @code{store}
3455 parameter is now implicit and is ``threaded'' in the calls to the
3456 @code{package->derivation} and @code{gexp->derivation} monadic
3457 procedures, and the monadic value returned by @code{package->derivation}
3458 is @dfn{bound} using @code{mlet} instead of plain @code{let}.
3460 As it turns out, the call to @code{package->derivation} can even be
3461 omitted since it will take place implicitly, as we will see later
3462 (@pxref{G-Expressions}):
3465 (define (sh-symlink)
3466 (gexp->derivation "sh"
3467 #~(symlink (string-append #$bash "/bin/bash")
3472 @c <https://syntaxexclamation.wordpress.com/2014/06/26/escaping-continuations/>
3473 @c for the funny quote.
3474 Calling the monadic @code{sh-symlink} has no effect. As someone once
3475 said, ``you exit a monad like you exit a building on fire: by running''.
3476 So, to exit the monad and get the desired effect, one must use
3477 @code{run-with-store}:
3480 (run-with-store (open-connection) (sh-symlink))
3481 @result{} /gnu/store/...-sh-symlink
3484 Note that the @code{(guix monad-repl)} module extends the Guile REPL with
3485 new ``meta-commands'' to make it easier to deal with monadic procedures:
3486 @code{run-in-store}, and @code{enter-store-monad}. The former is used
3487 to ``run'' a single monadic value through the store:
3490 scheme@@(guile-user)> ,run-in-store (package->derivation hello)
3491 $1 = #<derivation /gnu/store/@dots{}-hello-2.9.drv => @dots{}>
3494 The latter enters a recursive REPL, where all the return values are
3495 automatically run through the store:
3498 scheme@@(guile-user)> ,enter-store-monad
3499 store-monad@@(guile-user) [1]> (package->derivation hello)
3500 $2 = #<derivation /gnu/store/@dots{}-hello-2.9.drv => @dots{}>
3501 store-monad@@(guile-user) [1]> (text-file "foo" "Hello!")
3502 $3 = "/gnu/store/@dots{}-foo"
3503 store-monad@@(guile-user) [1]> ,q
3504 scheme@@(guile-user)>
3508 Note that non-monadic values cannot be returned in the
3509 @code{store-monad} REPL.
3511 The main syntactic forms to deal with monads in general are provided by
3512 the @code{(guix monads)} module and are described below.
3514 @deffn {Scheme Syntax} with-monad @var{monad} @var{body} ...
3515 Evaluate any @code{>>=} or @code{return} forms in @var{body} as being
3519 @deffn {Scheme Syntax} return @var{val}
3520 Return a monadic value that encapsulates @var{val}.
3523 @deffn {Scheme Syntax} >>= @var{mval} @var{mproc} ...
3524 @dfn{Bind} monadic value @var{mval}, passing its ``contents'' to monadic
3525 procedures @var{mproc}@dots{}@footnote{This operation is commonly
3526 referred to as ``bind'', but that name denotes an unrelated procedure in
3527 Guile. Thus we use this somewhat cryptic symbol inherited from the
3528 Haskell language.}. There can be one @var{mproc} or several of them, as
3533 (with-monad %state-monad
3535 (lambda (x) (return (+ 1 x)))
3536 (lambda (x) (return (* 2 x)))))
3540 @result{} some-state
3544 @deffn {Scheme Syntax} mlet @var{monad} ((@var{var} @var{mval}) ...) @
3546 @deffnx {Scheme Syntax} mlet* @var{monad} ((@var{var} @var{mval}) ...) @
3548 Bind the variables @var{var} to the monadic values @var{mval} in
3549 @var{body}. The form (@var{var} -> @var{val}) binds @var{var} to the
3550 ``normal'' value @var{val}, as per @code{let}.
3552 @code{mlet*} is to @code{mlet} what @code{let*} is to @code{let}
3553 (@pxref{Local Bindings,,, guile, GNU Guile Reference Manual}).
3556 @deffn {Scheme System} mbegin @var{monad} @var{mexp} ...
3557 Bind @var{mexp} and the following monadic expressions in sequence,
3558 returning the result of the last expression.
3560 This is akin to @code{mlet}, except that the return values of the
3561 monadic expressions are ignored. In that sense, it is analogous to
3562 @code{begin}, but applied to monadic expressions.
3566 The @code{(guix monads)} module provides the @dfn{state monad}, which
3567 allows an additional value---the state---to be @emph{threaded} through
3568 monadic procedure calls.
3570 @defvr {Scheme Variable} %state-monad
3571 The state monad. Procedures in the state monad can access and change
3572 the state that is threaded.
3574 Consider the example below. The @code{square} procedure returns a value
3575 in the state monad. It returns the square of its argument, but also
3576 increments the current state value:
3580 (mlet %state-monad ((count (current-state)))
3581 (mbegin %state-monad
3582 (set-current-state (+ 1 count))
3585 (run-with-state (sequence %state-monad (map square (iota 3))) 0)
3590 When ``run'' through @var{%state-monad}, we obtain that additional state
3591 value, which is the number of @code{square} calls.
3594 @deffn {Monadic Procedure} current-state
3595 Return the current state as a monadic value.
3598 @deffn {Monadic Procedure} set-current-state @var{value}
3599 Set the current state to @var{value} and return the previous state as a
3603 @deffn {Monadic Procedure} state-push @var{value}
3604 Push @var{value} to the current state, which is assumed to be a list,
3605 and return the previous state as a monadic value.
3608 @deffn {Monadic Procedure} state-pop
3609 Pop a value from the current state and return it as a monadic value.
3610 The state is assumed to be a list.
3613 @deffn {Scheme Procedure} run-with-state @var{mval} [@var{state}]
3614 Run monadic value @var{mval} starting with @var{state} as the initial
3615 state. Return two values: the resulting value, and the resulting state.
3618 The main interface to the store monad, provided by the @code{(guix
3619 store)} module, is as follows.
3621 @defvr {Scheme Variable} %store-monad
3622 The store monad---an alias for @var{%state-monad}.
3624 Values in the store monad encapsulate accesses to the store. When its
3625 effect is needed, a value of the store monad must be ``evaluated'' by
3626 passing it to the @code{run-with-store} procedure (see below.)
3629 @deffn {Scheme Procedure} run-with-store @var{store} @var{mval} [#:guile-for-build] [#:system (%current-system)]
3630 Run @var{mval}, a monadic value in the store monad, in @var{store}, an
3631 open store connection.
3634 @deffn {Monadic Procedure} text-file @var{name} @var{text} [@var{references}]
3635 Return as a monadic value the absolute file name in the store of the file
3636 containing @var{text}, a string. @var{references} is a list of store items that the
3637 resulting text file refers to; it defaults to the empty list.
3640 @deffn {Monadic Procedure} interned-file @var{file} [@var{name}] @
3641 [#:recursive? #t] [#:select? (const #t)]
3642 Return the name of @var{file} once interned in the store. Use
3643 @var{name} as its store name, or the basename of @var{file} if
3644 @var{name} is omitted.
3646 When @var{recursive?} is true, the contents of @var{file} are added
3647 recursively; if @var{file} designates a flat file and @var{recursive?}
3648 is true, its contents are added, and its permission bits are kept.
3650 When @var{recursive?} is true, call @code{(@var{select?} @var{file}
3651 @var{stat})} for each directory entry, where @var{file} is the entry's
3652 absolute file name and @var{stat} is the result of @code{lstat}; exclude
3653 entries for which @var{select?} does not return true.
3655 The example below adds a file to the store, under two different names:
3658 (run-with-store (open-connection)
3659 (mlet %store-monad ((a (interned-file "README"))
3660 (b (interned-file "README" "LEGU-MIN")))
3661 (return (list a b))))
3663 @result{} ("/gnu/store/rwm@dots{}-README" "/gnu/store/44i@dots{}-LEGU-MIN")
3668 The @code{(guix packages)} module exports the following package-related
3671 @deffn {Monadic Procedure} package-file @var{package} [@var{file}] @
3672 [#:system (%current-system)] [#:target #f] @
3675 value in the absolute file name of @var{file} within the @var{output}
3676 directory of @var{package}. When @var{file} is omitted, return the name
3677 of the @var{output} directory of @var{package}. When @var{target} is
3678 true, use it as a cross-compilation target triplet.
3681 @deffn {Monadic Procedure} package->derivation @var{package} [@var{system}]
3682 @deffnx {Monadic Procedure} package->cross-derivation @var{package} @
3683 @var{target} [@var{system}]
3684 Monadic version of @code{package-derivation} and
3685 @code{package-cross-derivation} (@pxref{Defining Packages}).
3690 @section G-Expressions
3692 @cindex G-expression
3693 @cindex build code quoting
3694 So we have ``derivations'', which represent a sequence of build actions
3695 to be performed to produce an item in the store (@pxref{Derivations}).
3696 These build actions are performed when asking the daemon to actually
3697 build the derivations; they are run by the daemon in a container
3698 (@pxref{Invoking guix-daemon}).
3700 @cindex strata of code
3701 It should come as no surprise that we like to write these build actions
3702 in Scheme. When we do that, we end up with two @dfn{strata} of Scheme
3703 code@footnote{The term @dfn{stratum} in this context was coined by
3704 Manuel Serrano et al.@: in the context of their work on Hop. Oleg
3705 Kiselyov, who has written insightful
3706 @url{http://okmij.org/ftp/meta-programming/#meta-scheme, essays and code
3707 on this topic}, refers to this kind of code generation as
3708 @dfn{staging}.}: the ``host code''---code that defines packages, talks
3709 to the daemon, etc.---and the ``build code''---code that actually
3710 performs build actions, such as making directories, invoking
3711 @command{make}, etc.
3713 To describe a derivation and its build actions, one typically needs to
3714 embed build code inside host code. It boils down to manipulating build
3715 code as data, and the homoiconicity of Scheme---code has a direct
3716 representation as data---comes in handy for that. But we need more than
3717 the normal @code{quasiquote} mechanism in Scheme to construct build
3720 The @code{(guix gexp)} module implements @dfn{G-expressions}, a form of
3721 S-expressions adapted to build expressions. G-expressions, or
3722 @dfn{gexps}, consist essentially of three syntactic forms: @code{gexp},
3723 @code{ungexp}, and @code{ungexp-splicing} (or simply: @code{#~},
3724 @code{#$}, and @code{#$@@}), which are comparable to
3725 @code{quasiquote}, @code{unquote}, and @code{unquote-splicing},
3726 respectively (@pxref{Expression Syntax, @code{quasiquote},, guile,
3727 GNU Guile Reference Manual}). However, there are major differences:
3731 Gexps are meant to be written to a file and run or manipulated by other
3735 When a high-level object such as a package or derivation is unquoted
3736 inside a gexp, the result is as if its output file name had been
3740 Gexps carry information about the packages or derivations they refer to,
3741 and these dependencies are automatically added as inputs to the build
3742 processes that use them.
3745 @cindex lowering, of high-level objects in gexps
3746 This mechanism is not limited to package and derivation
3747 objects: @dfn{compilers} able to ``lower'' other high-level objects to
3748 derivations or files in the store can be defined,
3749 such that these objects can also be inserted
3750 into gexps. For example, a useful type of high-level objects that can be
3751 inserted in a gexp is ``file-like objects'', which make it easy to
3752 add files to the store and to refer to them in
3753 derivations and such (see @code{local-file} and @code{plain-file}
3756 To illustrate the idea, here is an example of a gexp:
3763 (symlink (string-append #$coreutils "/bin/ls")
3767 This gexp can be passed to @code{gexp->derivation}; we obtain a
3768 derivation that builds a directory containing exactly one symlink to
3769 @file{/gnu/store/@dots{}-coreutils-8.22/bin/ls}:
3772 (gexp->derivation "the-thing" build-exp)
3775 As one would expect, the @code{"/gnu/store/@dots{}-coreutils-8.22"} string is
3776 substituted to the reference to the @var{coreutils} package in the
3777 actual build code, and @var{coreutils} is automatically made an input to
3778 the derivation. Likewise, @code{#$output} (equivalent to @code{(ungexp
3779 output)}) is replaced by a string containing the directory name of the
3780 output of the derivation.
3782 @cindex cross compilation
3783 In a cross-compilation context, it is useful to distinguish between
3784 references to the @emph{native} build of a package---that can run on the
3785 host---versus references to cross builds of a package. To that end, the
3786 @code{#+} plays the same role as @code{#$}, but is a reference to a
3787 native package build:
3790 (gexp->derivation "vi"
3793 (system* (string-append #+coreutils "/bin/ln")
3795 (string-append #$emacs "/bin/emacs")
3796 (string-append #$output "/bin/vi")))
3797 #:target "mips64el-linux")
3801 In the example above, the native build of @var{coreutils} is used, so
3802 that @command{ln} can actually run on the host; but then the
3803 cross-compiled build of @var{emacs} is referenced.
3805 @cindex imported modules, for gexps
3806 @findex with-imported-modules
3807 Another gexp feature is @dfn{imported modules}: sometimes you want to be
3808 able to use certain Guile modules from the ``host environment'' in the
3809 gexp, so those modules should be imported in the ``build environment''.
3810 The @code{with-imported-modules} form allows you to express that:
3813 (let ((build (with-imported-modules '((guix build utils))
3815 (use-modules (guix build utils))
3816 (mkdir-p (string-append #$output "/bin"))))))
3817 (gexp->derivation "empty-dir"
3820 (display "success!\n")
3825 In this example, the @code{(guix build utils)} module is automatically
3826 pulled into the isolated build environment of our gexp, such that
3827 @code{(use-modules (guix build utils))} works as expected.
3829 @cindex module closure
3830 @findex source-module-closure
3831 Usually you want the @emph{closure} of the module to be imported---i.e.,
3832 the module itself and all the modules it depends on---rather than just
3833 the module; failing to do that, attempts to use the module will fail
3834 because of missing dependent modules. The @code{source-module-closure}
3835 procedure computes the closure of a module by looking at its source file
3836 headers, which comes in handy in this case:
3839 (use-modules (guix modules)) ;for 'source-module-closure'
3841 (with-imported-modules (source-module-closure
3842 '((guix build utils)
3844 (gexp->derivation "something-with-vms"
3846 (use-modules (guix build utils)
3851 The syntactic form to construct gexps is summarized below.
3853 @deffn {Scheme Syntax} #~@var{exp}
3854 @deffnx {Scheme Syntax} (gexp @var{exp})
3855 Return a G-expression containing @var{exp}. @var{exp} may contain one
3856 or more of the following forms:
3860 @itemx (ungexp @var{obj})
3861 Introduce a reference to @var{obj}. @var{obj} may have one of the
3862 supported types, for example a package or a
3863 derivation, in which case the @code{ungexp} form is replaced by its
3864 output file name---e.g., @code{"/gnu/store/@dots{}-coreutils-8.22}.
3866 If @var{obj} is a list, it is traversed and references to supported
3867 objects are substituted similarly.
3869 If @var{obj} is another gexp, its contents are inserted and its
3870 dependencies are added to those of the containing gexp.
3872 If @var{obj} is another kind of object, it is inserted as is.
3874 @item #$@var{obj}:@var{output}
3875 @itemx (ungexp @var{obj} @var{output})
3876 This is like the form above, but referring explicitly to the
3877 @var{output} of @var{obj}---this is useful when @var{obj} produces
3878 multiple outputs (@pxref{Packages with Multiple Outputs}).
3881 @itemx #+@var{obj}:output
3882 @itemx (ungexp-native @var{obj})
3883 @itemx (ungexp-native @var{obj} @var{output})
3884 Same as @code{ungexp}, but produces a reference to the @emph{native}
3885 build of @var{obj} when used in a cross compilation context.
3887 @item #$output[:@var{output}]
3888 @itemx (ungexp output [@var{output}])
3889 Insert a reference to derivation output @var{output}, or to the main
3890 output when @var{output} is omitted.
3892 This only makes sense for gexps passed to @code{gexp->derivation}.
3895 @itemx (ungexp-splicing @var{lst})
3896 Like the above, but splices the contents of @var{lst} inside the
3900 @itemx (ungexp-native-splicing @var{lst})
3901 Like the above, but refers to native builds of the objects listed in
3906 G-expressions created by @code{gexp} or @code{#~} are run-time objects
3907 of the @code{gexp?} type (see below.)
3910 @deffn {Scheme Syntax} with-imported-modules @var{modules} @var{body}@dots{}
3911 Mark the gexps defined in @var{body}@dots{} as requiring @var{modules}
3912 in their execution environment. @var{modules} must be a list of Guile
3913 module names, such as @code{'((guix build utils) (guix build gremlin))}.
3915 This form has @emph{lexical} scope: it has an effect on the gexps
3916 directly defined in @var{body}@dots{}, but not on those defined, say, in
3917 procedures called from @var{body}@dots{}.
3920 @deffn {Scheme Procedure} gexp? @var{obj}
3921 Return @code{#t} if @var{obj} is a G-expression.
3924 G-expressions are meant to be written to disk, either as code building
3925 some derivation, or as plain files in the store. The monadic procedures
3926 below allow you to do that (@pxref{The Store Monad}, for more
3927 information about monads.)
3929 @deffn {Monadic Procedure} gexp->derivation @var{name} @var{exp} @
3930 [#:system (%current-system)] [#:target #f] [#:graft? #t] @
3931 [#:hash #f] [#:hash-algo #f] @
3932 [#:recursive? #f] [#:env-vars '()] [#:modules '()] @
3933 [#:module-path @var{%load-path}] @
3934 [#:references-graphs #f] [#:allowed-references #f] @
3935 [#:disallowed-references #f] @
3936 [#:leaked-env-vars #f] @
3937 [#:script-name (string-append @var{name} "-builder")] @
3938 [#:local-build? #f] [#:substitutable? #t] [#:guile-for-build #f]
3939 Return a derivation @var{name} that runs @var{exp} (a gexp) with
3940 @var{guile-for-build} (a derivation) on @var{system}; @var{exp} is
3941 stored in a file called @var{script-name}. When @var{target} is true,
3942 it is used as the cross-compilation target triplet for packages referred
3945 @var{modules} is deprecated in favor of @code{with-imported-modules}.
3947 make @var{modules} available in the evaluation context of @var{exp};
3948 @var{modules} is a list of names of Guile modules searched in
3949 @var{module-path} to be copied in the store, compiled, and made available in
3950 the load path during the execution of @var{exp}---e.g., @code{((guix
3951 build utils) (guix build gnu-build-system))}.
3953 @var{graft?} determines whether packages referred to by @var{exp} should be grafted when
3956 When @var{references-graphs} is true, it must be a list of tuples of one of the
3960 (@var{file-name} @var{package})
3961 (@var{file-name} @var{package} @var{output})
3962 (@var{file-name} @var{derivation})
3963 (@var{file-name} @var{derivation} @var{output})
3964 (@var{file-name} @var{store-item})
3967 The right-hand-side of each element of @var{references-graphs} is automatically made
3968 an input of the build process of @var{exp}. In the build environment, each
3969 @var{file-name} contains the reference graph of the corresponding item, in a simple
3972 @var{allowed-references} must be either @code{#f} or a list of output names and packages.
3973 In the latter case, the list denotes store items that the result is allowed to
3974 refer to. Any reference to another store item will lead to a build error.
3975 Similarly for @var{disallowed-references}, which can list items that must not be
3976 referenced by the outputs.
3978 The other arguments are as for @code{derivation} (@pxref{Derivations}).
3981 @cindex file-like objects
3982 The @code{local-file}, @code{plain-file}, @code{computed-file},
3983 @code{program-file}, and @code{scheme-file} procedures below return
3984 @dfn{file-like objects}. That is, when unquoted in a G-expression,
3985 these objects lead to a file in the store. Consider this G-expression:
3988 #~(system* (string-append #$glibc "/sbin/nscd") "-f"
3989 #$(local-file "/tmp/my-nscd.conf"))
3992 The effect here is to ``intern'' @file{/tmp/my-nscd.conf} by copying it
3993 to the store. Once expanded, for instance @i{via}
3994 @code{gexp->derivation}, the G-expression refers to that copy under
3995 @file{/gnu/store}; thus, modifying or removing the file in @file{/tmp}
3996 does not have any effect on what the G-expression does.
3997 @code{plain-file} can be used similarly; it differs in that the file
3998 content is directly passed as a string.
4000 @deffn {Scheme Procedure} local-file @var{file} [@var{name}] @
4001 [#:recursive? #f] [#:select? (const #t)]
4002 Return an object representing local file @var{file} to add to the store; this
4003 object can be used in a gexp. If @var{file} is a relative file name, it is looked
4004 up relative to the source file where this form appears. @var{file} will be added to
4005 the store under @var{name}--by default the base name of @var{file}.
4007 When @var{recursive?} is true, the contents of @var{file} are added recursively; if @var{file}
4008 designates a flat file and @var{recursive?} is true, its contents are added, and its
4009 permission bits are kept.
4011 When @var{recursive?} is true, call @code{(@var{select?} @var{file}
4012 @var{stat})} for each directory entry, where @var{file} is the entry's
4013 absolute file name and @var{stat} is the result of @code{lstat}; exclude
4014 entries for which @var{select?} does not return true.
4016 This is the declarative counterpart of the @code{interned-file} monadic
4017 procedure (@pxref{The Store Monad, @code{interned-file}}).
4020 @deffn {Scheme Procedure} plain-file @var{name} @var{content}
4021 Return an object representing a text file called @var{name} with the given
4022 @var{content} (a string) to be added to the store.
4024 This is the declarative counterpart of @code{text-file}.
4027 @deffn {Scheme Procedure} computed-file @var{name} @var{gexp} @
4028 [#:options '(#:local-build? #t)]
4029 Return an object representing the store item @var{name}, a file or
4030 directory computed by @var{gexp}. @var{options}
4031 is a list of additional arguments to pass to @code{gexp->derivation}.
4033 This is the declarative counterpart of @code{gexp->derivation}.
4036 @deffn {Monadic Procedure} gexp->script @var{name} @var{exp}
4037 Return an executable script @var{name} that runs @var{exp} using
4038 @var{guile}, with @var{exp}'s imported modules in its search path.
4040 The example below builds a script that simply invokes the @command{ls}
4044 (use-modules (guix gexp) (gnu packages base))
4046 (gexp->script "list-files"
4047 #~(execl (string-append #$coreutils "/bin/ls")
4051 When ``running'' it through the store (@pxref{The Store Monad,
4052 @code{run-with-store}}), we obtain a derivation that produces an
4053 executable file @file{/gnu/store/@dots{}-list-files} along these lines:
4056 #!/gnu/store/@dots{}-guile-2.0.11/bin/guile -ds
4058 (execl (string-append "/gnu/store/@dots{}-coreutils-8.22"/bin/ls")
4063 @deffn {Scheme Procedure} program-file @var{name} @var{exp} @
4065 Return an object representing the executable store item @var{name} that
4066 runs @var{gexp}. @var{guile} is the Guile package used to execute that
4069 This is the declarative counterpart of @code{gexp->script}.
4072 @deffn {Monadic Procedure} gexp->file @var{name} @var{exp} @
4073 [#:set-load-path? #t]
4074 Return a derivation that builds a file @var{name} containing @var{exp}.
4075 When @var{set-load-path?} is true, emit code in the resulting file to
4076 set @code{%load-path} and @code{%load-compiled-path} to honor
4077 @var{exp}'s imported modules.
4079 The resulting file holds references to all the dependencies of @var{exp}
4080 or a subset thereof.
4083 @deffn {Scheme Procedure} scheme-file @var{name} @var{exp}
4084 Return an object representing the Scheme file @var{name} that contains
4087 This is the declarative counterpart of @code{gexp->file}.
4090 @deffn {Monadic Procedure} text-file* @var{name} @var{text} @dots{}
4091 Return as a monadic value a derivation that builds a text file
4092 containing all of @var{text}. @var{text} may list, in addition to
4093 strings, objects of any type that can be used in a gexp: packages,
4094 derivations, local file objects, etc. The resulting store file holds
4095 references to all these.
4097 This variant should be preferred over @code{text-file} anytime the file
4098 to create will reference items from the store. This is typically the
4099 case when building a configuration file that embeds store file names,
4103 (define (profile.sh)
4104 ;; Return the name of a shell script in the store that
4105 ;; initializes the 'PATH' environment variable.
4106 (text-file* "profile.sh"
4107 "export PATH=" coreutils "/bin:"
4108 grep "/bin:" sed "/bin\n"))
4111 In this example, the resulting @file{/gnu/store/@dots{}-profile.sh} file
4112 will reference @var{coreutils}, @var{grep}, and @var{sed}, thereby
4113 preventing them from being garbage-collected during its lifetime.
4116 @deffn {Scheme Procedure} mixed-text-file @var{name} @var{text} @dots{}
4117 Return an object representing store file @var{name} containing
4118 @var{text}. @var{text} is a sequence of strings and file-like objects,
4122 (mixed-text-file "profile"
4123 "export PATH=" coreutils "/bin:" grep "/bin")
4126 This is the declarative counterpart of @code{text-file*}.
4129 Of course, in addition to gexps embedded in ``host'' code, there are
4130 also modules containing build tools. To make it clear that they are
4131 meant to be used in the build stratum, these modules are kept in the
4132 @code{(guix build @dots{})} name space.
4134 @cindex lowering, of high-level objects in gexps
4135 Internally, high-level objects are @dfn{lowered}, using their compiler,
4136 to either derivations or store items. For instance, lowering a package
4137 yields a derivation, and lowering a @code{plain-file} yields a store
4138 item. This is achieved using the @code{lower-object} monadic procedure.
4140 @deffn {Monadic Procedure} lower-object @var{obj} [@var{system}] @
4142 Return as a value in @var{%store-monad} the derivation or store item
4143 corresponding to @var{obj} for @var{system}, cross-compiling for
4144 @var{target} if @var{target} is true. @var{obj} must be an object that
4145 has an associated gexp compiler, such as a @code{<package>}.
4149 @c *********************************************************************
4153 This section describes Guix command-line utilities. Some of them are
4154 primarily targeted at developers and users who write new package
4155 definitions, while others are more generally useful. They complement
4156 the Scheme programming interface of Guix in a convenient way.
4159 * Invoking guix build:: Building packages from the command line.
4160 * Invoking guix edit:: Editing package definitions.
4161 * Invoking guix download:: Downloading a file and printing its hash.
4162 * Invoking guix hash:: Computing the cryptographic hash of a file.
4163 * Invoking guix import:: Importing package definitions.
4164 * Invoking guix refresh:: Updating package definitions.
4165 * Invoking guix lint:: Finding errors in package definitions.
4166 * Invoking guix size:: Profiling disk usage.
4167 * Invoking guix graph:: Visualizing the graph of packages.
4168 * Invoking guix environment:: Setting up development environments.
4169 * Invoking guix publish:: Sharing substitutes.
4170 * Invoking guix challenge:: Challenging substitute servers.
4171 * Invoking guix container:: Process isolation.
4174 @node Invoking guix build
4175 @section Invoking @command{guix build}
4177 The @command{guix build} command builds packages or derivations and
4178 their dependencies, and prints the resulting store paths. Note that it
4179 does not modify the user's profile---this is the job of the
4180 @command{guix package} command (@pxref{Invoking guix package}). Thus,
4181 it is mainly useful for distribution developers.
4183 The general syntax is:
4186 guix build @var{options} @var{package-or-derivation}@dots{}
4189 As an example, the following command builds the latest versions of Emacs
4190 and of Guile, displays their build logs, and finally displays the
4191 resulting directories:
4194 guix build emacs guile
4197 Similarly, the following command builds all the available packages:
4200 guix build --quiet --keep-going \
4201 `guix package -A | cut -f1,2 --output-delimiter=@@`
4204 @var{package-or-derivation} may be either the name of a package found in
4205 the software distribution such as @code{coreutils} or
4206 @code{coreutils-8.20}, or a derivation such as
4207 @file{/gnu/store/@dots{}-coreutils-8.19.drv}. In the former case, a
4208 package with the corresponding name (and optionally version) is searched
4209 for among the GNU distribution modules (@pxref{Package Modules}).
4211 Alternatively, the @code{--expression} option may be used to specify a
4212 Scheme expression that evaluates to a package; this is useful when
4213 disambiguating among several same-named packages or package variants is
4216 There may be zero or more @var{options}. The available options are
4217 described in the subsections below.
4220 * Common Build Options:: Build options for most commands.
4221 * Package Transformation Options:: Creating variants of packages.
4222 * Additional Build Options:: Options specific to 'guix build'.
4225 @node Common Build Options
4226 @subsection Common Build Options
4228 A number of options that control the build process are common to
4229 @command{guix build} and other commands that can spawn builds, such as
4230 @command{guix package} or @command{guix archive}. These are the
4235 @item --load-path=@var{directory}
4236 @itemx -L @var{directory}
4237 Add @var{directory} to the front of the package module search path
4238 (@pxref{Package Modules}).
4240 This allows users to define their own packages and make them visible to
4241 the command-line tools.
4245 Keep the build tree of failed builds. Thus, if a build fails, its build
4246 tree is kept under @file{/tmp}, in a directory whose name is shown at
4247 the end of the build log. This is useful when debugging build issues.
4251 Keep going when some of the derivations fail to build; return only once
4252 all the builds have either completed or failed.
4254 The default behavior is to stop as soon as one of the specified
4255 derivations has failed.
4259 Do not build the derivations.
4262 When substituting a pre-built binary fails, fall back to building
4265 @item --substitute-urls=@var{urls}
4266 @anchor{client-substitute-urls}
4267 Consider @var{urls} the whitespace-separated list of substitute source
4268 URLs, overriding the default list of URLs of @command{guix-daemon}
4269 (@pxref{daemon-substitute-urls,, @command{guix-daemon} URLs}).
4271 This means that substitutes may be downloaded from @var{urls}, provided
4272 they are signed by a key authorized by the system administrator
4273 (@pxref{Substitutes}).
4275 When @var{urls} is the empty string, substitutes are effectively
4278 @item --no-substitutes
4279 Do not use substitutes for build products. That is, always build things
4280 locally instead of allowing downloads of pre-built binaries
4281 (@pxref{Substitutes}).
4284 Do not ``graft'' packages. In practice, this means that package updates
4285 available as grafts are not applied. @xref{Security Updates}, for more
4286 information on grafts.
4288 @item --rounds=@var{n}
4289 Build each derivation @var{n} times in a row, and raise an error if
4290 consecutive build results are not bit-for-bit identical.
4292 This is a useful way to detect non-deterministic builds processes.
4293 Non-deterministic build processes are a problem because they make it
4294 practically impossible for users to @emph{verify} whether third-party
4295 binaries are genuine. @xref{Invoking guix challenge}, for more.
4297 Note that, currently, the differing build results are not kept around,
4298 so you will have to manually investigate in case of an error---e.g., by
4299 stashing one of the build results with @code{guix archive --export}
4300 (@pxref{Invoking guix archive}), then rebuilding, and finally comparing
4303 @item --no-build-hook
4304 Do not attempt to offload builds @i{via} the ``build hook'' of the daemon
4305 (@pxref{Daemon Offload Setup}). That is, always build things locally
4306 instead of offloading builds to remote machines.
4308 @item --max-silent-time=@var{seconds}
4309 When the build or substitution process remains silent for more than
4310 @var{seconds}, terminate it and report a build failure.
4312 @item --timeout=@var{seconds}
4313 Likewise, when the build or substitution process lasts for more than
4314 @var{seconds}, terminate it and report a build failure.
4316 By default there is no timeout. This behavior can be restored with
4319 @item --verbosity=@var{level}
4320 Use the given verbosity level. @var{level} must be an integer between 0
4321 and 5; higher means more verbose output. Setting a level of 4 or more
4322 may be helpful when debugging setup issues with the build daemon.
4324 @item --cores=@var{n}
4326 Allow the use of up to @var{n} CPU cores for the build. The special
4327 value @code{0} means to use as many CPU cores as available.
4329 @item --max-jobs=@var{n}
4331 Allow at most @var{n} build jobs in parallel. @xref{Invoking
4332 guix-daemon, @code{--max-jobs}}, for details about this option and the
4333 equivalent @command{guix-daemon} option.
4337 Behind the scenes, @command{guix build} is essentially an interface to
4338 the @code{package-derivation} procedure of the @code{(guix packages)}
4339 module, and to the @code{build-derivations} procedure of the @code{(guix
4340 derivations)} module.
4342 In addition to options explicitly passed on the command line,
4343 @command{guix build} and other @command{guix} commands that support
4344 building honor the @code{GUIX_BUILD_OPTIONS} environment variable.
4346 @defvr {Environment Variable} GUIX_BUILD_OPTIONS
4347 Users can define this variable to a list of command line options that
4348 will automatically be used by @command{guix build} and other
4349 @command{guix} commands that can perform builds, as in the example
4353 $ export GUIX_BUILD_OPTIONS="--no-substitutes -c 2 -L /foo/bar"
4356 These options are parsed independently, and the result is appended to
4357 the parsed command-line options.
4361 @node Package Transformation Options
4362 @subsection Package Transformation Options
4364 @cindex package variants
4365 Another set of command-line options supported by @command{guix build}
4366 and also @command{guix package} are @dfn{package transformation
4367 options}. These are options that make it possible to define @dfn{package
4368 variants}---for instance, packages built from different source code.
4369 This is a convenient way to create customized packages on the fly
4370 without having to type in the definitions of package variants
4371 (@pxref{Defining Packages}).
4375 @item --with-source=@var{source}
4376 Use @var{source} as the source of the corresponding package.
4377 @var{source} must be a file name or a URL, as for @command{guix
4378 download} (@pxref{Invoking guix download}).
4380 The ``corresponding package'' is taken to be the one specified on the
4381 command line the name of which matches the base of @var{source}---e.g.,
4382 if @var{source} is @code{/src/guile-2.0.10.tar.gz}, the corresponding
4383 package is @code{guile}. Likewise, the version string is inferred from
4384 @var{source}; in the previous example, it is @code{2.0.10}.
4386 This option allows users to try out versions of packages other than the
4387 one provided by the distribution. The example below downloads
4388 @file{ed-1.7.tar.gz} from a GNU mirror and uses that as the source for
4389 the @code{ed} package:
4392 guix build ed --with-source=mirror://gnu/ed/ed-1.7.tar.gz
4395 As a developer, @code{--with-source} makes it easy to test release
4399 guix build guile --with-source=../guile-2.0.9.219-e1bb7.tar.xz
4402 @dots{} or to build from a checkout in a pristine environment:
4405 $ git clone git://git.sv.gnu.org/guix.git
4406 $ guix build guix --with-source=./guix
4409 @item --with-input=@var{package}=@var{replacement}
4410 Replace dependency on @var{package} by a dependency on
4411 @var{replacement}. @var{package} must be a package name, and
4412 @var{replacement} must be a package specification such as @code{guile}
4413 or @code{guile@@1.8}.
4415 For instance, the following command builds Guix, but replaces its
4416 dependency on the current stable version of Guile with a dependency on
4417 the development version of Guile, @code{guile-next}:
4420 guix build --with-input=guile=guile-next guix
4423 This is a recursive, deep replacement. So in this example, both
4424 @code{guix} and its dependency @code{guile-json} (which also depends on
4425 @code{guile}) get rebuilt against @code{guile-next}.
4427 This is implemented using the @code{package-input-rewriting} Scheme
4428 procedure (@pxref{Defining Packages, @code{package-input-rewriting}}).
4431 @node Additional Build Options
4432 @subsection Additional Build Options
4434 The command-line options presented below are specific to @command{guix
4441 Build quietly, without displaying the build log. Upon completion, the
4442 build log is kept in @file{/var} (or similar) and can always be
4443 retrieved using the @option{--log-file} option.
4445 @item --file=@var{file}
4446 @itemx -f @var{file}
4448 Build the package or derivation that the code within @var{file}
4451 As an example, @var{file} might contain a package definition like this
4452 (@pxref{Defining Packages}):
4455 @verbatiminclude package-hello.scm
4458 @item --expression=@var{expr}
4459 @itemx -e @var{expr}
4460 Build the package or derivation @var{expr} evaluates to.
4462 For example, @var{expr} may be @code{(@@ (gnu packages guile)
4463 guile-1.8)}, which unambiguously designates this specific variant of
4464 version 1.8 of Guile.
4466 Alternatively, @var{expr} may be a G-expression, in which case it is used
4467 as a build program passed to @code{gexp->derivation}
4468 (@pxref{G-Expressions}).
4470 Lastly, @var{expr} may refer to a zero-argument monadic procedure
4471 (@pxref{The Store Monad}). The procedure must return a derivation as a
4472 monadic value, which is then passed through @code{run-with-store}.
4476 Build the source derivations of the packages, rather than the packages
4479 For instance, @code{guix build -S gcc} returns something like
4480 @file{/gnu/store/@dots{}-gcc-4.7.2.tar.bz2}, which is the GCC
4483 The returned source tarball is the result of applying any patches and
4484 code snippets specified in the package @code{origin} (@pxref{Defining
4488 Fetch and return the source of @var{package-or-derivation} and all their
4489 dependencies, recursively. This is a handy way to obtain a local copy
4490 of all the source code needed to build @var{packages}, allowing you to
4491 eventually build them even without network access. It is an extension
4492 of the @code{--source} option and can accept one of the following
4493 optional argument values:
4497 This value causes the @code{--sources} option to behave in the same way
4498 as the @code{--source} option.
4501 Build the source derivations of all packages, including any source that
4502 might be listed as @code{inputs}. This is the default value.
4505 $ guix build --sources tzdata
4506 The following derivations will be built:
4507 /gnu/store/@dots{}-tzdata2015b.tar.gz.drv
4508 /gnu/store/@dots{}-tzcode2015b.tar.gz.drv
4512 Build the source derivations of all packages, as well of all transitive
4513 inputs to the packages. This can be used e.g. to
4514 prefetch package source for later offline building.
4517 $ guix build --sources=transitive tzdata
4518 The following derivations will be built:
4519 /gnu/store/@dots{}-tzcode2015b.tar.gz.drv
4520 /gnu/store/@dots{}-findutils-4.4.2.tar.xz.drv
4521 /gnu/store/@dots{}-grep-2.21.tar.xz.drv
4522 /gnu/store/@dots{}-coreutils-8.23.tar.xz.drv
4523 /gnu/store/@dots{}-make-4.1.tar.xz.drv
4524 /gnu/store/@dots{}-bash-4.3.tar.xz.drv
4530 @item --system=@var{system}
4531 @itemx -s @var{system}
4532 Attempt to build for @var{system}---e.g., @code{i686-linux}---instead of
4533 the system type of the build host.
4535 An example use of this is on Linux-based systems, which can emulate
4536 different personalities. For instance, passing
4537 @code{--system=i686-linux} on an @code{x86_64-linux} system allows users
4538 to build packages in a complete 32-bit environment.
4540 @item --target=@var{triplet}
4541 @cindex cross-compilation
4542 Cross-build for @var{triplet}, which must be a valid GNU triplet, such
4543 as @code{"mips64el-linux-gnu"} (@pxref{Configuration Names, GNU
4544 configuration triplets,, configure, GNU Configure and Build System}).
4546 @anchor{build-check}
4548 @cindex determinism, checking
4549 @cindex reproducibility, checking
4550 Rebuild @var{package-or-derivation}, which are already available in the
4551 store, and raise an error if the build results are not bit-for-bit
4554 This mechanism allows you to check whether previously installed
4555 substitutes are genuine (@pxref{Substitutes}), or whether the build result
4556 of a package is deterministic. @xref{Invoking guix challenge}, for more
4557 background information and tools.
4559 When used in conjunction with @option{--keep-failed}, the differing
4560 output is kept in the store, under @file{/gnu/store/@dots{}-check}.
4561 This makes it easy to look for differences between the two results.
4565 Return the derivation paths, not the output paths, of the given
4568 @item --root=@var{file}
4569 @itemx -r @var{file}
4570 Make @var{file} a symlink to the result, and register it as a garbage
4574 Return the build log file names or URLs for the given
4575 @var{package-or-derivation}, or raise an error if build logs are
4578 This works regardless of how packages or derivations are specified. For
4579 instance, the following invocations are equivalent:
4582 guix build --log-file `guix build -d guile`
4583 guix build --log-file `guix build guile`
4584 guix build --log-file guile
4585 guix build --log-file -e '(@@ (gnu packages guile) guile-2.0)'
4588 If a log is unavailable locally, and unless @code{--no-substitutes} is
4589 passed, the command looks for a corresponding log on one of the
4590 substitute servers (as specified with @code{--substitute-urls}.)
4592 So for instance, imagine you want to see the build log of GDB on MIPS,
4593 but you are actually on an @code{x86_64} machine:
4596 $ guix build --log-file gdb -s mips64el-linux
4597 https://hydra.gnu.org/log/@dots{}-gdb-7.10
4600 You can freely access a huge library of build logs!
4604 @node Invoking guix edit
4605 @section Invoking @command{guix edit}
4607 @cindex package definition, editing
4608 So many packages, so many source files! The @command{guix edit} command
4609 facilitates the life of users and packagers by pointing their editor at
4610 the source file containing the definition of the specified packages.
4614 guix edit gcc@@4.9 vim
4618 launches the program specified in the @code{VISUAL} or in the
4619 @code{EDITOR} environment variable to view the recipe of GCC@tie{}4.9.3
4622 If you are using a Guix Git checkout (@pxref{Building from Git}), or
4623 have created your own packages on @code{GUIX_PACKAGE_PATH}
4624 (@pxref{Defining Packages}), you will be able to edit the package
4625 recipes. Otherwise, you will be able to examine the read-only recipes
4626 for packages currently in the store.
4628 If you are using Emacs, note that the Emacs user interface provides the
4629 @kbd{M-x guix-edit} command and a similar functionality in the ``package
4630 info'' and ``package list'' buffers created by the @kbd{M-x
4631 guix-search-by-name} and similar commands (@pxref{Emacs Commands}).
4634 @node Invoking guix download
4635 @section Invoking @command{guix download}
4637 When writing a package definition, developers typically need to download
4638 a source tarball, compute its SHA256 hash, and write that
4639 hash in the package definition (@pxref{Defining Packages}). The
4640 @command{guix download} tool helps with this task: it downloads a file
4641 from the given URI, adds it to the store, and prints both its file name
4642 in the store and its SHA256 hash.
4644 The fact that the downloaded file is added to the store saves bandwidth:
4645 when the developer eventually tries to build the newly defined package
4646 with @command{guix build}, the source tarball will not have to be
4647 downloaded again because it is already in the store. It is also a
4648 convenient way to temporarily stash files, which may be deleted
4649 eventually (@pxref{Invoking guix gc}).
4651 The @command{guix download} command supports the same URIs as used in
4652 package definitions. In particular, it supports @code{mirror://} URIs.
4653 @code{https} URIs (HTTP over TLS) are supported @emph{provided} the
4654 Guile bindings for GnuTLS are available in the user's environment; when
4655 they are not available, an error is raised. @xref{Guile Preparations,
4656 how to install the GnuTLS bindings for Guile,, gnutls-guile,
4657 GnuTLS-Guile}, for more information.
4659 The following option is available:
4662 @item --format=@var{fmt}
4664 Write the hash in the format specified by @var{fmt}. For more
4665 information on the valid values for @var{fmt}, @pxref{Invoking guix hash}.
4668 @node Invoking guix hash
4669 @section Invoking @command{guix hash}
4671 The @command{guix hash} command computes the SHA256 hash of a file.
4672 It is primarily a convenience tool for anyone contributing to the
4673 distribution: it computes the cryptographic hash of a file, which can be
4674 used in the definition of a package (@pxref{Defining Packages}).
4676 The general syntax is:
4679 guix hash @var{option} @var{file}
4682 @command{guix hash} has the following options:
4686 @item --format=@var{fmt}
4688 Write the hash in the format specified by @var{fmt}.
4690 Supported formats: @code{nix-base32}, @code{base32}, @code{base16}
4691 (@code{hex} and @code{hexadecimal} can be used as well).
4693 If the @option{--format} option is not specified, @command{guix hash}
4694 will output the hash in @code{nix-base32}. This representation is used
4695 in the definitions of packages.
4699 Compute the hash on @var{file} recursively.
4701 In this case, the hash is computed on an archive containing @var{file},
4702 including its children if it is a directory. Some of the metadata of
4703 @var{file} is part of the archive; for instance, when @var{file} is a
4704 regular file, the hash is different depending on whether @var{file} is
4705 executable or not. Metadata such as time stamps has no impact on the
4706 hash (@pxref{Invoking guix archive}).
4707 @c FIXME: Replace xref above with xref to an ``Archive'' section when
4712 When combined with @option{--recursive}, exclude version control system
4713 directories (@file{.bzr}, @file{.git}, @file{.hg}, etc.)
4716 As an example, here is how you would compute the hash of a Git checkout,
4717 which is useful when using the @code{git-fetch} method (@pxref{origin
4721 $ git clone http://example.org/foo.git
4727 @node Invoking guix import
4728 @section Invoking @command{guix import}
4730 @cindex importing packages
4731 @cindex package import
4732 @cindex package conversion
4733 The @command{guix import} command is useful for people who would like to
4734 add a package to the distribution with as little work as
4735 possible---a legitimate demand. The command knows of a few
4736 repositories from which it can ``import'' package metadata. The result
4737 is a package definition, or a template thereof, in the format we know
4738 (@pxref{Defining Packages}).
4740 The general syntax is:
4743 guix import @var{importer} @var{options}@dots{}
4746 @var{importer} specifies the source from which to import package
4747 metadata, and @var{options} specifies a package identifier and other
4748 options specific to @var{importer}. Currently, the available
4753 Import metadata for the given GNU package. This provides a template
4754 for the latest version of that GNU package, including the hash of its
4755 source tarball, and its canonical synopsis and description.
4757 Additional information such as the package dependencies and its
4758 license needs to be figured out manually.
4760 For example, the following command returns a package definition for
4764 guix import gnu hello
4767 Specific command-line options are:
4770 @item --key-download=@var{policy}
4771 As for @code{guix refresh}, specify the policy to handle missing OpenPGP
4772 keys when verifying the package signature. @xref{Invoking guix
4773 refresh, @code{--key-download}}.
4778 Import metadata from the @uref{https://pypi.python.org/, Python Package
4779 Index}@footnote{This functionality requires Guile-JSON to be installed.
4780 @xref{Requirements}.}. Information is taken from the JSON-formatted
4781 description available at @code{pypi.python.org} and usually includes all
4782 the relevant information, including package dependencies. For maximum
4783 efficiency, it is recommended to install the @command{unzip} utility, so
4784 that the importer can unzip Python wheels and gather data from them.
4786 The command below imports metadata for the @code{itsdangerous} Python
4790 guix import pypi itsdangerous
4795 Import metadata from @uref{https://rubygems.org/,
4796 RubyGems}@footnote{This functionality requires Guile-JSON to be
4797 installed. @xref{Requirements}.}. Information is taken from the
4798 JSON-formatted description available at @code{rubygems.org} and includes
4799 most relevant information, including runtime dependencies. There are
4800 some caveats, however. The metadata doesn't distinguish between
4801 synopses and descriptions, so the same string is used for both fields.
4802 Additionally, the details of non-Ruby dependencies required to build
4803 native extensions is unavailable and left as an exercise to the
4806 The command below imports metadata for the @code{rails} Ruby package:
4809 guix import gem rails
4814 Import metadata from @uref{https://www.metacpan.org/, MetaCPAN}@footnote{This
4815 functionality requires Guile-JSON to be installed.
4816 @xref{Requirements}.}.
4817 Information is taken from the JSON-formatted metadata provided through
4818 @uref{https://api.metacpan.org/, MetaCPAN's API} and includes most
4819 relevant information, such as module dependencies. License information
4820 should be checked closely. If Perl is available in the store, then the
4821 @code{corelist} utility will be used to filter core modules out of the
4822 list of dependencies.
4824 The command command below imports metadata for the @code{Acme::Boolean}
4828 guix import cpan Acme::Boolean
4833 @cindex Bioconductor
4834 Import metadata from @uref{http://cran.r-project.org/, CRAN}, the
4835 central repository for the @uref{http://r-project.org, GNU@tie{}R
4836 statistical and graphical environment}.
4838 Information is extracted from the @code{DESCRIPTION} file of the package.
4840 The command command below imports metadata for the @code{Cairo}
4844 guix import cran Cairo
4847 When @code{--archive=bioconductor} is added, metadata is imported from
4848 @uref{http://www.bioconductor.org/, Bioconductor}, a repository of R
4849 packages for for the analysis and comprehension of high-throughput
4850 genomic data in bioinformatics.
4852 Information is extracted from the @code{DESCRIPTION} file of a package
4853 published on the web interface of the Bioconductor SVN repository.
4855 The command below imports metadata for the @code{GenomicRanges}
4859 guix import cran --archive=bioconductor GenomicRanges
4863 Import metadata from a local copy of the source of the
4864 @uref{http://nixos.org/nixpkgs/, Nixpkgs distribution}@footnote{This
4865 relies on the @command{nix-instantiate} command of
4866 @uref{http://nixos.org/nix/, Nix}.}. Package definitions in Nixpkgs are
4867 typically written in a mixture of Nix-language and Bash code. This
4868 command only imports the high-level package structure that is written in
4869 the Nix language. It normally includes all the basic fields of a
4872 When importing a GNU package, the synopsis and descriptions are replaced
4873 by their canonical upstream variant.
4875 Usually, you will first need to do:
4878 export NIX_REMOTE=daemon
4882 so that @command{nix-instantiate} does not try to open the Nix database.
4884 As an example, the command below imports the package definition of
4885 LibreOffice (more precisely, it imports the definition of the package
4886 bound to the @code{libreoffice} top-level attribute):
4889 guix import nix ~/path/to/nixpkgs libreoffice
4894 Import metadata from the Haskell community's central package archive
4895 @uref{https://hackage.haskell.org/, Hackage}. Information is taken from
4896 Cabal files and includes all the relevant information, including package
4899 Specific command-line options are:
4904 Read a Cabal file from standard input.
4905 @item --no-test-dependencies
4907 Do not include dependencies required only by the test suites.
4908 @item --cabal-environment=@var{alist}
4909 @itemx -e @var{alist}
4910 @var{alist} is a Scheme alist defining the environment in which the
4911 Cabal conditionals are evaluated. The accepted keys are: @code{os},
4912 @code{arch}, @code{impl} and a string representing the name of a flag.
4913 The value associated with a flag has to be either the symbol
4914 @code{true} or @code{false}. The value associated with other keys
4915 has to conform to the Cabal file format definition. The default value
4916 associated with the keys @code{os}, @code{arch} and @code{impl} is
4917 @samp{linux}, @samp{x86_64} and @samp{ghc}, respectively.
4920 The command below imports metadata for the latest version of the
4921 @code{HTTP} Haskell package without including test dependencies and
4922 specifying the value of the flag @samp{network-uri} as @code{false}:
4925 guix import hackage -t -e "'((\"network-uri\" . false))" HTTP
4928 A specific package version may optionally be specified by following the
4929 package name by an at-sign and a version number as in the following example:
4932 guix import hackage mtl@@2.1.3.1
4937 Import metadata from an Emacs Lisp Package Archive (ELPA) package
4938 repository (@pxref{Packages,,, emacs, The GNU Emacs Manual}).
4940 Specific command-line options are:
4943 @item --archive=@var{repo}
4944 @itemx -a @var{repo}
4945 @var{repo} identifies the archive repository from which to retrieve the
4946 information. Currently the supported repositories and their identifiers
4950 @uref{http://elpa.gnu.org/packages, GNU}, selected by the @code{gnu}
4951 identifier. This is the default.
4954 @uref{http://stable.melpa.org/packages, MELPA-Stable}, selected by the
4955 @code{melpa-stable} identifier.
4958 @uref{http://melpa.org/packages, MELPA}, selected by the @code{melpa}
4964 The structure of the @command{guix import} code is modular. It would be
4965 useful to have more importers for other package formats, and your help
4966 is welcome here (@pxref{Contributing}).
4968 @node Invoking guix refresh
4969 @section Invoking @command{guix refresh}
4971 The primary audience of the @command{guix refresh} command is developers
4972 of the GNU software distribution. By default, it reports any packages
4973 provided by the distribution that are outdated compared to the latest
4974 upstream version, like this:
4978 gnu/packages/gettext.scm:29:13: gettext would be upgraded from 0.18.1.1 to 0.18.2.1
4979 gnu/packages/glib.scm:77:12: glib would be upgraded from 2.34.3 to 2.37.0
4982 It does so by browsing the FTP directory of each package and determining
4983 the highest version number of the source tarballs therein. The command
4984 knows how to update specific types of packages: GNU packages, ELPA
4985 packages, etc.---see the documentation for @option{--type} below. The
4986 are many packages, though, for which it lacks a method to determine
4987 whether a new upstream release is available. However, the mechanism is
4988 extensible, so feel free to get in touch with us to add a new method!
4990 When passed @code{--update}, it modifies distribution source files to
4991 update the version numbers and source tarball hashes of those package
4992 recipes (@pxref{Defining Packages}). This is achieved by downloading
4993 each package's latest source tarball and its associated OpenPGP
4994 signature, authenticating the downloaded tarball against its signature
4995 using @command{gpg}, and finally computing its hash. When the public
4996 key used to sign the tarball is missing from the user's keyring, an
4997 attempt is made to automatically retrieve it from a public key server;
4998 when this is successful, the key is added to the user's keyring; otherwise,
4999 @command{guix refresh} reports an error.
5001 The following options are supported:
5005 @item --expression=@var{expr}
5006 @itemx -e @var{expr}
5007 Consider the package @var{expr} evaluates to.
5009 This is useful to precisely refer to a package, as in this example:
5012 guix refresh -l -e '(@@@@ (gnu packages commencement) glibc-final)'
5015 This command lists the dependents of the ``final'' libc (essentially all
5020 Update distribution source files (package recipes) in place. This is
5021 usually run from a checkout of the Guix source tree (@pxref{Running
5022 Guix Before It Is Installed}):
5025 $ ./pre-inst-env guix refresh -s non-core
5028 @xref{Defining Packages}, for more information on package definitions.
5030 @item --select=[@var{subset}]
5031 @itemx -s @var{subset}
5032 Select all the packages in @var{subset}, one of @code{core} or
5035 The @code{core} subset refers to all the packages at the core of the
5036 distribution---i.e., packages that are used to build ``everything
5037 else''. This includes GCC, libc, Binutils, Bash, etc. Usually,
5038 changing one of these packages in the distribution entails a rebuild of
5039 all the others. Thus, such updates are an inconvenience to users in
5040 terms of build time or bandwidth used to achieve the upgrade.
5042 The @code{non-core} subset refers to the remaining packages. It is
5043 typically useful in cases where an update of the core packages would be
5046 @item --type=@var{updater}
5047 @itemx -t @var{updater}
5048 Select only packages handled by @var{updater} (may be a comma-separated
5049 list of updaters). Currently, @var{updater} may be one of:
5053 the updater for GNU packages;
5055 the updater for GNOME packages;
5057 the updater for KDE packages;
5059 the updater for X.org packages;
5061 the updater for @uref{http://elpa.gnu.org/, ELPA} packages;
5063 the updater for @uref{http://cran.r-project.org/, CRAN} packages;
5065 the updater for @uref{http://www.bioconductor.org/, Bioconductor} R packages;
5067 the updater for @uref{https://pypi.python.org, PyPI} packages.
5069 the updater for @uref{https://rubygems.org, RubyGems} packages.
5071 the updater for @uref{https://github.com, GitHub} packages.
5073 the updater for @uref{https://hackage.haskell.org, Hackage} packages.
5076 For instance, the following command only checks for updates of Emacs
5077 packages hosted at @code{elpa.gnu.org} and for updates of CRAN packages:
5080 $ guix refresh --type=elpa,cran
5081 gnu/packages/statistics.scm:819:13: r-testthat would be upgraded from 0.10.0 to 0.11.0
5082 gnu/packages/emacs.scm:856:13: emacs-auctex would be upgraded from 11.88.6 to 11.88.9
5087 In addition, @command{guix refresh} can be passed one or more package
5088 names, as in this example:
5091 $ ./pre-inst-env guix refresh -u emacs idutils gcc-4.8.4
5095 The command above specifically updates the @code{emacs} and
5096 @code{idutils} packages. The @code{--select} option would have no
5097 effect in this case.
5099 When considering whether to upgrade a package, it is sometimes
5100 convenient to know which packages would be affected by the upgrade and
5101 should be checked for compatibility. For this the following option may
5102 be used when passing @command{guix refresh} one or more package names:
5106 @item --list-updaters
5108 List available updaters and exit (see @option{--type} above.)
5110 @item --list-dependent
5112 List top-level dependent packages that would need to be rebuilt as a
5113 result of upgrading one or more packages.
5117 Be aware that the @code{--list-dependent} option only
5118 @emph{approximates} the rebuilds that would be required as a result of
5119 an upgrade. More rebuilds might be required under some circumstances.
5122 $ guix refresh --list-dependent flex
5123 Building the following 120 packages would ensure 213 dependent packages are rebuilt:
5124 hop-2.4.0 geiser-0.4 notmuch-0.18 mu-0.9.9.5 cflow-1.4 idutils-4.6 @dots{}
5127 The command above lists a set of packages that could be built to check
5128 for compatibility with an upgraded @code{flex} package.
5130 The following options can be used to customize GnuPG operation:
5134 @item --gpg=@var{command}
5135 Use @var{command} as the GnuPG 2.x command. @var{command} is searched
5136 for in @code{$PATH}.
5138 @item --key-download=@var{policy}
5139 Handle missing OpenPGP keys according to @var{policy}, which may be one
5144 Always download missing OpenPGP keys from the key server, and add them
5145 to the user's GnuPG keyring.
5148 Never try to download missing OpenPGP keys. Instead just bail out.
5151 When a package signed with an unknown OpenPGP key is encountered, ask
5152 the user whether to download it or not. This is the default behavior.
5155 @item --key-server=@var{host}
5156 Use @var{host} as the OpenPGP key server when importing a public key.
5160 The @code{github} updater uses the
5161 @uref{https://developer.github.com/v3/, GitHub API} to query for new
5162 releases. When used repeatedly e.g. when refreshing all packages,
5163 GitHub will eventually refuse to answer any further API requests. By
5164 default 60 API requests per hour are allowed, and a full refresh on all
5165 GitHub packages in Guix requires more than this. Authentication with
5166 GitHub through the use of an API token alleviates these limits. To use
5167 an API token, set the environment variable @code{GUIX_GITHUB_TOKEN} to a
5168 token procured from @uref{https://github.com/settings/tokens} or
5172 @node Invoking guix lint
5173 @section Invoking @command{guix lint}
5174 The @command{guix lint} command is meant to help package developers avoid
5175 common errors and use a consistent style. It runs a number of checks on
5176 a given set of packages in order to find common mistakes in their
5177 definitions. Available @dfn{checkers} include (see
5178 @code{--list-checkers} for a complete list):
5183 Validate certain typographical and stylistic rules about package
5184 descriptions and synopses.
5186 @item inputs-should-be-native
5187 Identify inputs that should most likely be native inputs.
5191 @itemx source-file-name
5192 Probe @code{home-page} and @code{source} URLs and report those that are
5193 invalid. Check that the source file name is meaningful, e.g. is not
5194 just a version number or ``git-checkout'', without a declared
5195 @code{file-name} (@pxref{origin Reference}).
5198 @cindex security vulnerabilities
5199 @cindex CVE, Common Vulnerabilities and Exposures
5200 Report known vulnerabilities found in the Common Vulnerabilities and
5201 Exposures (CVE) databases of the current and past year
5202 @uref{https://nvd.nist.gov/download.cfm#CVE_FEED, published by the US
5205 To view information about a particular vulnerability, visit pages such as:
5209 @indicateurl{https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-YYYY-ABCD}
5211 @indicateurl{https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-YYYY-ABCD}
5215 where @code{CVE-YYYY-ABCD} is the CVE identifier---e.g.,
5216 @code{CVE-2015-7554}.
5218 Package developers can specify in package recipes the
5219 @uref{https://nvd.nist.gov/cpe.cfm,Common Platform Enumeration (CPE)}
5220 name and version of the package when they differ from the name that Guix
5221 uses, as in this example:
5227 ;; CPE calls this package "grub2".
5228 (properties '((cpe-name . "grub2"))))
5232 Warn about obvious source code formatting issues: trailing white space,
5233 use of tabulations, etc.
5236 The general syntax is:
5239 guix lint @var{options} @var{package}@dots{}
5242 If no package is given on the command line, then all packages are checked.
5243 The @var{options} may be zero or more of the following:
5246 @item --list-checkers
5248 List and describe all the available checkers that will be run on packages
5253 Only enable the checkers specified in a comma-separated list using the
5254 names returned by @code{--list-checkers}.
5258 @node Invoking guix size
5259 @section Invoking @command{guix size}
5261 The @command{guix size} command helps package developers profile the
5262 disk usage of packages. It is easy to overlook the impact of an
5263 additional dependency added to a package, or the impact of using a
5264 single output for a package that could easily be split (@pxref{Packages
5265 with Multiple Outputs}). Such are the typical issues that
5266 @command{guix size} can highlight.
5268 The command can be passed a package specification such as @code{gcc-4.8}
5269 or @code{guile:debug}, or a file name in the store. Consider this
5273 $ guix size coreutils
5274 store item total self
5275 /gnu/store/@dots{}-coreutils-8.23 70.0 13.9 19.8%
5276 /gnu/store/@dots{}-gmp-6.0.0a 55.3 2.5 3.6%
5277 /gnu/store/@dots{}-acl-2.2.52 53.7 0.5 0.7%
5278 /gnu/store/@dots{}-attr-2.4.46 53.2 0.3 0.5%
5279 /gnu/store/@dots{}-gcc-4.8.4-lib 52.9 15.7 22.4%
5280 /gnu/store/@dots{}-glibc-2.21 37.2 37.2 53.1%
5284 The store items listed here constitute the @dfn{transitive closure} of
5285 Coreutils---i.e., Coreutils and all its dependencies, recursively---as
5286 would be returned by:
5289 $ guix gc -R /gnu/store/@dots{}-coreutils-8.23
5292 Here the output shows three columns next to store items. The first column,
5293 labeled ``total'', shows the size in mebibytes (MiB) of the closure of
5294 the store item---that is, its own size plus the size of all its
5295 dependencies. The next column, labeled ``self'', shows the size of the
5296 item itself. The last column shows the ratio of the size of the item
5297 itself to the space occupied by all the items listed here.
5299 In this example, we see that the closure of Coreutils weighs in at
5300 70@tie{}MiB, half of which is taken by libc. (That libc represents a
5301 large fraction of the closure is not a problem @i{per se} because it is
5302 always available on the system anyway.)
5304 When the package passed to @command{guix size} is available in the
5305 store, @command{guix size} queries the daemon to determine its
5306 dependencies, and measures its size in the store, similar to @command{du
5307 -ms --apparent-size} (@pxref{du invocation,,, coreutils, GNU
5310 When the given package is @emph{not} in the store, @command{guix size}
5311 reports information based on the available substitutes
5312 (@pxref{Substitutes}). This makes it possible it to profile disk usage of
5313 store items that are not even on disk, only available remotely.
5315 You can also specify several package names:
5318 $ guix size coreutils grep sed bash
5319 store item total self
5320 /gnu/store/@dots{}-coreutils-8.24 77.8 13.8 13.4%
5321 /gnu/store/@dots{}-grep-2.22 73.1 0.8 0.8%
5322 /gnu/store/@dots{}-bash-4.3.42 72.3 4.7 4.6%
5323 /gnu/store/@dots{}-readline-6.3 67.6 1.2 1.2%
5329 In this example we see that the combination of the four packages takes
5330 102.3@tie{}MiB in total, which is much less than the sum of each closure
5331 since they have a lot of dependencies in common.
5333 The available options are:
5337 @item --substitute-urls=@var{urls}
5338 Use substitute information from @var{urls}.
5339 @xref{client-substitute-urls, the same option for @code{guix build}}.
5341 @item --map-file=@var{file}
5342 Write a graphical map of disk usage in PNG format to @var{file}.
5344 For the example above, the map looks like this:
5346 @image{images/coreutils-size-map,5in,, map of Coreutils disk usage
5347 produced by @command{guix size}}
5349 This option requires that
5350 @uref{http://wingolog.org/software/guile-charting/, Guile-Charting} be
5351 installed and visible in Guile's module search path. When that is not
5352 the case, @command{guix size} fails as it tries to load it.
5354 @item --system=@var{system}
5355 @itemx -s @var{system}
5356 Consider packages for @var{system}---e.g., @code{x86_64-linux}.
5360 @node Invoking guix graph
5361 @section Invoking @command{guix graph}
5364 Packages and their dependencies form a @dfn{graph}, specifically a
5365 directed acyclic graph (DAG). It can quickly become difficult to have a
5366 mental model of the package DAG, so the @command{guix graph} command
5367 provides a visual representation of the DAG. @command{guix graph}
5368 emits a DAG representation in the input format of
5369 @uref{http://www.graphviz.org/, Graphviz}, so its output can be passed
5370 directly to the @command{dot} command of Graphviz. The general
5374 guix graph @var{options} @var{package}@dots{}
5377 For example, the following command generates a PDF file representing the
5378 package DAG for the GNU@tie{}Core Utilities, showing its build-time
5382 guix graph coreutils | dot -Tpdf > dag.pdf
5385 The output looks like this:
5387 @image{images/coreutils-graph,2in,,Dependency graph of the GNU Coreutils}
5389 Nice little graph, no?
5391 But there is more than one graph! The one above is concise: it is the
5392 graph of package objects, omitting implicit inputs such as GCC, libc,
5393 grep, etc. It is often useful to have such a concise graph, but
5394 sometimes one may want to see more details. @command{guix graph} supports
5395 several types of graphs, allowing you to choose the level of detail:
5399 This is the default type used in the example above. It shows the DAG of
5400 package objects, excluding implicit dependencies. It is concise, but
5401 filters out many details.
5404 This is the package DAG, @emph{including} implicit inputs.
5406 For instance, the following command:
5409 guix graph --type=bag-emerged coreutils | dot -Tpdf > dag.pdf
5412 ... yields this bigger graph:
5414 @image{images/coreutils-bag-graph,,5in,Detailed dependency graph of the GNU Coreutils}
5416 At the bottom of the graph, we see all the implicit inputs of
5417 @var{gnu-build-system} (@pxref{Build Systems, @code{gnu-build-system}}).
5419 Now, note that the dependencies of these implicit inputs---that is, the
5420 @dfn{bootstrap dependencies} (@pxref{Bootstrapping})---are not shown
5421 here, for conciseness.
5424 Similar to @code{bag-emerged}, but this time including all the bootstrap
5427 @item bag-with-origins
5428 Similar to @code{bag}, but also showing origins and their dependencies.
5431 This is the most detailed representation: It shows the DAG of
5432 derivations (@pxref{Derivations}) and plain store items. Compared to
5433 the above representation, many additional nodes are visible, including
5434 build scripts, patches, Guile modules, etc.
5436 For this type of graph, it is also possible to pass a @file{.drv} file
5437 name instead of a package name, as in:
5440 guix graph -t derivation `guix system build -d my-config.scm`
5444 All the types above correspond to @emph{build-time dependencies}. The
5445 following graph type represents the @emph{run-time dependencies}:
5449 This is the graph of @dfn{references} of a package output, as returned
5450 by @command{guix gc --references} (@pxref{Invoking guix gc}).
5452 If the given package output is not available in the store, @command{guix
5453 graph} attempts to obtain dependency information from substitutes.
5455 Here you can also pass a store file name instead of a package name. For
5456 example, the command below produces the reference graph of your profile
5457 (which can be big!):
5460 guix graph -t references `readlink -f ~/.guix-profile`
5464 The available options are the following:
5467 @item --type=@var{type}
5468 @itemx -t @var{type}
5469 Produce a graph output of @var{type}, where @var{type} must be one of
5470 the values listed above.
5473 List the supported graph types.
5475 @item --expression=@var{expr}
5476 @itemx -e @var{expr}
5477 Consider the package @var{expr} evaluates to.
5479 This is useful to precisely refer to a package, as in this example:
5482 guix graph -e '(@@@@ (gnu packages commencement) gnu-make-final)'
5487 @node Invoking guix environment
5488 @section Invoking @command{guix environment}
5490 @cindex reproducible build environments
5491 @cindex development environments
5492 The purpose of @command{guix environment} is to assist hackers in
5493 creating reproducible development environments without polluting their
5494 package profile. The @command{guix environment} tool takes one or more
5495 packages, builds all of their inputs, and creates a shell
5496 environment to use them.
5498 The general syntax is:
5501 guix environment @var{options} @var{package}@dots{}
5504 The following example spawns a new shell set up for the development of
5508 guix environment guile
5511 If the needed dependencies are not built yet, @command{guix environment}
5512 automatically builds them. The environment of the new shell is an augmented
5513 version of the environment that @command{guix environment} was run in.
5514 It contains the necessary search paths for building the given package
5515 added to the existing environment variables. To create a ``pure''
5516 environment, in which the original environment variables have been unset,
5517 use the @code{--pure} option@footnote{Users sometimes wrongfully augment
5518 environment variables such as @code{PATH} in their @file{~/.bashrc}
5519 file. As a consequence, when @code{guix environment} launches it, Bash
5520 may read @file{~/.bashrc}, thereby introducing ``impurities'' in these
5521 environment variables. It is an error to define such environment
5522 variables in @file{.bashrc}; instead, they should be defined in
5523 @file{.bash_profile}, which is sourced only by log-in shells.
5524 @xref{Bash Startup Files,,, bash, The GNU Bash Reference Manual}, for
5525 details on Bash start-up files.}.
5527 @vindex GUIX_ENVIRONMENT
5528 @command{guix environment} defines the @code{GUIX_ENVIRONMENT}
5529 variable in the shell it spawns; its value is the file name of the
5530 profile of this environment. This allows users to, say, define a
5531 specific prompt for development environments in their @file{.bashrc}
5532 (@pxref{Bash Startup Files,,, bash, The GNU Bash Reference Manual}):
5535 if [ -n "$GUIX_ENVIRONMENT" ]
5537 export PS1="\u@@\h \w [dev]\$ "
5542 ... or to browse the profile:
5545 $ ls "$GUIX_ENVIRONMENT/bin"
5548 Additionally, more than one package may be specified, in which case the
5549 union of the inputs for the given packages are used. For example, the
5550 command below spawns a shell where all of the dependencies of both Guile
5551 and Emacs are available:
5554 guix environment guile emacs
5557 Sometimes an interactive shell session is not desired. An arbitrary
5558 command may be invoked by placing the @code{--} token to separate the
5559 command from the rest of the arguments:
5562 guix environment guile -- make -j4
5565 In other situations, it is more convenient to specify the list of
5566 packages needed in the environment. For example, the following command
5567 runs @command{python} from an environment containing Python@tie{}2.7 and
5571 guix environment --ad-hoc python2-numpy python-2.7 -- python
5574 Furthermore, one might want the dependencies of a package and also some
5575 additional packages that are not build-time or runtime dependencies, but
5576 are useful when developing nonetheless. Because of this, the
5577 @code{--ad-hoc} flag is positional. Packages appearing before
5578 @code{--ad-hoc} are interpreted as packages whose dependencies will be
5579 added to the environment. Packages appearing after are interpreted as
5580 packages that will be added to the environment directly. For example,
5581 the following command creates a Guix development environment that
5582 additionally includes Git and strace:
5585 guix environment guix --ad-hoc git strace
5588 Sometimes it is desirable to isolate the environment as much as
5589 possible, for maximal purity and reproducibility. In particular, when
5590 using Guix on a host distro that is not GuixSD, it is desirable to
5591 prevent access to @file{/usr/bin} and other system-wide resources from
5592 the development environment. For example, the following command spawns
5593 a Guile REPL in a ``container'' where only the store and the current
5594 working directory are mounted:
5597 guix environment --ad-hoc --container guile -- guile
5601 The @code{--container} option requires Linux-libre 3.19 or newer.
5604 The available options are summarized below.
5607 @item --expression=@var{expr}
5608 @itemx -e @var{expr}
5609 Create an environment for the package or list of packages that
5610 @var{expr} evaluates to.
5612 For example, running:
5615 guix environment -e '(@@ (gnu packages maths) petsc-openmpi)'
5618 starts a shell with the environment for this specific variant of the
5624 guix environment --ad-hoc -e '(@@ (gnu) %base-packages)'
5627 starts a shell with all the GuixSD base packages available.
5629 The above commands only the use default output of the given packages.
5630 To select other outputs, two element tuples can be specified:
5633 guix environment --ad-hoc -e '(list (@ (gnu packages bash) bash) "include")'
5636 @item --load=@var{file}
5637 @itemx -l @var{file}
5638 Create an environment for the package or list of packages that the code
5639 within @var{file} evaluates to.
5641 As an example, @var{file} might contain a definition like this
5642 (@pxref{Defining Packages}):
5645 @verbatiminclude environment-gdb.scm
5649 Include all specified packages in the resulting environment, as if an
5650 @i{ad hoc} package were defined with them as inputs. This option is
5651 useful for quickly creating an environment without having to write a
5652 package expression to contain the desired inputs.
5654 For instance, the command:
5657 guix environment --ad-hoc guile guile-sdl -- guile
5660 runs @command{guile} in an environment where Guile and Guile-SDL are
5663 Note that this example implicitly asks for the default output of
5664 @code{guile} and @code{guile-sdl}, but it is possible to ask for a
5665 specific output---e.g., @code{glib:bin} asks for the @code{bin} output
5666 of @code{glib} (@pxref{Packages with Multiple Outputs}).
5668 This option may be composed with the default behavior of @command{guix
5669 environment}. Packages appearing before @code{--ad-hoc} are interpreted
5670 as packages whose dependencies will be added to the environment, the
5671 default behavior. Packages appearing after are interpreted as packages
5672 that will be added to the environment directly.
5675 Unset existing environment variables when building the new environment.
5676 This has the effect of creating an environment in which search paths
5677 only contain package inputs.
5679 @item --search-paths
5680 Display the environment variable definitions that make up the
5683 @item --system=@var{system}
5684 @itemx -s @var{system}
5685 Attempt to build for @var{system}---e.g., @code{i686-linux}.
5690 Run @var{command} within an isolated container. The current working
5691 directory outside the container is mapped inside the container.
5692 Additionally, a dummy home directory is created that matches the current
5693 user's home directory, and @file{/etc/passwd} is configured accordingly.
5694 The spawned process runs as the current user outside the container, but
5695 has root privileges in the context of the container.
5699 For containers, share the network namespace with the host system.
5700 Containers created without this flag only have access to the loopback
5703 @item --expose=@var{source}[=@var{target}]
5704 For containers, expose the file system @var{source} from the host system
5705 as the read-only file system @var{target} within the container. If
5706 @var{target} is not specified, @var{source} is used as the target mount
5707 point in the container.
5709 The example below spawns a Guile REPL in a container in which the user's
5710 home directory is accessible read-only via the @file{/exchange}
5714 guix environment --container --expose=$HOME=/exchange guile -- guile
5717 @item --share=@var{source}[=@var{target}]
5718 For containers, share the file system @var{source} from the host system
5719 as the writable file system @var{target} within the container. If
5720 @var{target} is not specified, @var{source} is used as the target mount
5721 point in the container.
5723 The example below spawns a Guile REPL in a container in which the user's
5724 home directory is accessible for both reading and writing via the
5725 @file{/exchange} directory:
5728 guix environment --container --share=$HOME=/exchange guile -- guile
5732 It also supports all of the common build options that @command{guix
5733 build} supports (@pxref{Common Build Options}).
5735 @node Invoking guix publish
5736 @section Invoking @command{guix publish}
5738 The purpose of @command{guix publish} is to enable users to easily share
5739 their store with others, who can then use it as a substitute server
5740 (@pxref{Substitutes}).
5742 When @command{guix publish} runs, it spawns an HTTP server which allows
5743 anyone with network access to obtain substitutes from it. This means
5744 that any machine running Guix can also act as if it were a build farm,
5745 since the HTTP interface is compatible with Hydra, the software behind
5746 the @code{hydra.gnu.org} build farm.
5748 For security, each substitute is signed, allowing recipients to check
5749 their authenticity and integrity (@pxref{Substitutes}). Because
5750 @command{guix publish} uses the signing key of the system, which is only
5751 readable by the system administrator, it must be started as root; the
5752 @code{--user} option makes it drop root privileges early on.
5754 The signing key pair must be generated before @command{guix publish} is
5755 launched, using @command{guix archive --generate-key} (@pxref{Invoking
5758 The general syntax is:
5761 guix publish @var{options}@dots{}
5764 Running @command{guix publish} without any additional arguments will
5765 spawn an HTTP server on port 8080:
5771 Once a publishing server has been authorized (@pxref{Invoking guix
5772 archive}), the daemon may download substitutes from it:
5775 guix-daemon --substitute-urls=http://example.org:8080
5778 As a bonus, @command{guix publish} also serves as a content-addressed
5779 mirror for source files referenced in @code{origin} records
5780 (@pxref{origin Reference}). For instance, assuming @command{guix
5781 publish} is running on @code{example.org}, the following URL returns the
5782 raw @file{hello-2.10.tar.gz} file with the given SHA256 hash
5783 (represented in @code{nix-base32} format, @pxref{Invoking guix hash}):
5786 http://example.org/file/hello-2.10.tar.gz/sha256/0ssi1@dots{}ndq1i
5789 Obviously, these URLs only work for files that are in the store; in
5790 other cases, they return 404 (``Not Found'').
5792 The following options are available:
5795 @item --port=@var{port}
5796 @itemx -p @var{port}
5797 Listen for HTTP requests on @var{port}.
5799 @item --listen=@var{host}
5800 Listen on the network interface for @var{host}. The default is to
5801 accept connections from any interface.
5803 @item --user=@var{user}
5804 @itemx -u @var{user}
5805 Change privileges to @var{user} as soon as possible---i.e., once the
5806 server socket is open and the signing key has been read.
5808 @item --compression[=@var{level}]
5809 @itemx -C [@var{level}]
5810 Compress data using the given @var{level}. When @var{level} is zero,
5811 disable compression. The range 1 to 9 corresponds to different gzip
5812 compression levels: 1 is the fastest, and 9 is the best (CPU-intensive).
5815 Compression occurs on the fly and the compressed streams are not
5816 cached. Thus, to reduce load on the machine that runs @command{guix
5817 publish}, it may be a good idea to choose a low compression level, or to
5818 run @command{guix publish} behind a caching proxy.
5820 @item --ttl=@var{ttl}
5821 Produce @code{Cache-Control} HTTP headers that advertise a time-to-live
5822 (TTL) of @var{ttl}. @var{ttl} must denote a duration: @code{5d} means 5
5823 days, @code{1m} means 1 month, and so on.
5825 This allows the user's Guix to keep substitute information in cache for
5826 @var{ttl}. However, note that @code{guix publish} does not itself
5827 guarantee that the store items it provides will indeed remain available
5828 for as long as @var{ttl}.
5830 @item --repl[=@var{port}]
5831 @itemx -r [@var{port}]
5832 Spawn a Guile REPL server (@pxref{REPL Servers,,, guile, GNU Guile
5833 Reference Manual}) on @var{port} (37146 by default). This is used
5834 primarily for debugging a running @command{guix publish} server.
5837 Enabling @command{guix publish} on a GuixSD system is a one-liner: just
5838 add a call to @code{guix-publish-service} in the @code{services} field
5839 of the @code{operating-system} declaration (@pxref{guix-publish-service,
5840 @code{guix-publish-service}}).
5843 @node Invoking guix challenge
5844 @section Invoking @command{guix challenge}
5846 @cindex reproducible builds
5847 @cindex verifiable builds
5849 Do the binaries provided by this server really correspond to the source
5850 code it claims to build? Is a package build process deterministic?
5851 These are the questions the @command{guix challenge} command attempts to
5854 The former is obviously an important question: Before using a substitute
5855 server (@pxref{Substitutes}), one had better @emph{verify} that it
5856 provides the right binaries, and thus @emph{challenge} it. The latter
5857 is what enables the former: If package builds are deterministic, then
5858 independent builds of the package should yield the exact same result,
5859 bit for bit; if a server provides a binary different from the one
5860 obtained locally, it may be either corrupt or malicious.
5862 We know that the hash that shows up in @file{/gnu/store} file names is
5863 the hash of all the inputs of the process that built the file or
5864 directory---compilers, libraries, build scripts,
5865 etc. (@pxref{Introduction}). Assuming deterministic build processes,
5866 one store file name should map to exactly one build output.
5867 @command{guix challenge} checks whether there is, indeed, a single
5868 mapping by comparing the build outputs of several independent builds of
5869 any given store item.
5871 The command output looks like this:
5874 $ guix challenge --substitute-urls="https://hydra.gnu.org https://guix.example.org"
5875 updating list of substitutes from 'https://hydra.gnu.org'... 100.0%
5876 updating list of substitutes from 'https://guix.example.org'... 100.0%
5877 /gnu/store/@dots{}-openssl-1.0.2d contents differ:
5878 local hash: 0725l22r5jnzazaacncwsvp9kgf42266ayyp814v7djxs7nk963q
5879 https://hydra.gnu.org/nar/@dots{}-openssl-1.0.2d: 0725l22r5jnzazaacncwsvp9kgf42266ayyp814v7djxs7nk963q
5880 https://guix.example.org/nar/@dots{}-openssl-1.0.2d: 1zy4fmaaqcnjrzzajkdn3f5gmjk754b43qkq47llbyak9z0qjyim
5881 /gnu/store/@dots{}-git-2.5.0 contents differ:
5882 local hash: 00p3bmryhjxrhpn2gxs2fy0a15lnip05l97205pgbk5ra395hyha
5883 https://hydra.gnu.org/nar/@dots{}-git-2.5.0: 069nb85bv4d4a6slrwjdy8v1cn4cwspm3kdbmyb81d6zckj3nq9f
5884 https://guix.example.org/nar/@dots{}-git-2.5.0: 0mdqa9w1p6cmli6976v4wi0sw9r4p5prkj7lzfd1877wk11c9c73
5885 /gnu/store/@dots{}-pius-2.1.1 contents differ:
5886 local hash: 0k4v3m9z1zp8xzzizb7d8kjj72f9172xv078sq4wl73vnq9ig3ax
5887 https://hydra.gnu.org/nar/@dots{}-pius-2.1.1: 0k4v3m9z1zp8xzzizb7d8kjj72f9172xv078sq4wl73vnq9ig3ax
5888 https://guix.example.org/nar/@dots{}-pius-2.1.1: 1cy25x1a4fzq5rk0pmvc8xhwyffnqz95h2bpvqsz2mpvlbccy0gs
5892 In this example, @command{guix challenge} first scans the store to
5893 determine the set of locally-built derivations---as opposed to store
5894 items that were downloaded from a substitute server---and then queries
5895 all the substitute servers. It then reports those store items for which
5896 the servers obtained a result different from the local build.
5898 @cindex non-determinism, in package builds
5899 As an example, @code{guix.example.org} always gets a different answer.
5900 Conversely, @code{hydra.gnu.org} agrees with local builds, except in the
5901 case of Git. This might indicate that the build process of Git is
5902 non-deterministic, meaning that its output varies as a function of
5903 various things that Guix does not fully control, in spite of building
5904 packages in isolated environments (@pxref{Features}). Most common
5905 sources of non-determinism include the addition of timestamps in build
5906 results, the inclusion of random numbers, and directory listings sorted
5907 by inode number. See @uref{https://reproducible-builds.org/docs/}, for
5910 To find out what is wrong with this Git binary, we can do something along
5911 these lines (@pxref{Invoking guix archive}):
5914 $ wget -q -O - https://hydra.gnu.org/nar/@dots{}-git-2.5.0 \
5915 | guix archive -x /tmp/git
5916 $ diff -ur --no-dereference /gnu/store/@dots{}-git.2.5.0 /tmp/git
5919 This command shows the difference between the files resulting from the
5920 local build, and the files resulting from the build on
5921 @code{hydra.gnu.org} (@pxref{Overview, Comparing and Merging Files,,
5922 diffutils, Comparing and Merging Files}). The @command{diff} command
5923 works great for text files. When binary files differ, a better option
5924 is @uref{https://diffoscope.org/, Diffoscope}, a tool that helps
5925 visualize differences for all kinds of files.
5927 Once you have done that work, you can tell whether the differences are due
5928 to a non-deterministic build process or to a malicious server. We try
5929 hard to remove sources of non-determinism in packages to make it easier
5930 to verify substitutes, but of course, this is a process that
5931 involves not just Guix, but a large part of the free software community.
5932 In the meantime, @command{guix challenge} is one tool to help address
5935 If you are writing packages for Guix, you are encouraged to check
5936 whether @code{hydra.gnu.org} and other substitute servers obtain the
5937 same build result as you did with:
5940 $ guix challenge @var{package}
5944 where @var{package} is a package specification such as
5945 @code{guile@@2.0} or @code{glibc:debug}.
5947 The general syntax is:
5950 guix challenge @var{options} [@var{packages}@dots{}]
5953 When a difference is found between the hash of a locally-built item and
5954 that of a server-provided substitute, or among substitutes provided by
5955 different servers, the command displays it as in the example above and
5956 its exit code is 2 (other non-zero exit codes denote other kinds of
5959 The one option that matters is:
5963 @item --substitute-urls=@var{urls}
5964 Consider @var{urls} the whitespace-separated list of substitute source
5970 @node Invoking guix container
5971 @section Invoking @command{guix container}
5975 As of version @value{VERSION}, this tool is experimental. The interface
5976 is subject to radical change in the future.
5979 The purpose of @command{guix container} is to manipulate processes
5980 running within an isolated environment, commonly known as a
5981 ``container'', typically created by the @command{guix environment}
5982 (@pxref{Invoking guix environment}) and @command{guix system container}
5983 (@pxref{Invoking guix system}) commands.
5985 The general syntax is:
5988 guix container @var{action} @var{options}@dots{}
5991 @var{action} specifies the operation to perform with a container, and
5992 @var{options} specifies the context-specific arguments for the action.
5994 The following actions are available:
5998 Execute a command within the context of a running container.
6003 guix container exec @var{pid} @var{program} @var{arguments}@dots{}
6006 @var{pid} specifies the process ID of the running container.
6007 @var{program} specifies an executable file name within the root file
6008 system of the container. @var{arguments} are the additional options that
6009 will be passed to @var{program}.
6011 The following command launches an interactive login shell inside a
6012 GuixSD container, started by @command{guix system container}, and whose
6016 guix container exec 9001 /run/current-system/profile/bin/bash --login
6019 Note that the @var{pid} cannot be the parent process of a container. It
6020 must be PID 1 of the container or one of its child processes.
6024 @c *********************************************************************
6025 @node GNU Distribution
6026 @chapter GNU Distribution
6028 @cindex Guix System Distribution
6030 Guix comes with a distribution of the GNU system consisting entirely of
6031 free software@footnote{The term ``free'' here refers to the
6032 @url{http://www.gnu.org/philosophy/free-sw.html,freedom provided to
6033 users of that software}.}. The
6034 distribution can be installed on its own (@pxref{System Installation}),
6035 but it is also possible to install Guix as a package manager on top of
6036 an installed GNU/Linux system (@pxref{Installation}). To distinguish
6037 between the two, we refer to the standalone distribution as the Guix
6038 System Distribution, or GuixSD.
6040 The distribution provides core GNU packages such as GNU libc, GCC, and
6041 Binutils, as well as many GNU and non-GNU applications. The complete
6042 list of available packages can be browsed
6043 @url{http://www.gnu.org/software/guix/packages,on-line} or by
6044 running @command{guix package} (@pxref{Invoking guix package}):
6047 guix package --list-available
6050 Our goal is to provide a practical 100% free software distribution of
6051 Linux-based and other variants of GNU, with a focus on the promotion and
6052 tight integration of GNU components, and an emphasis on programs and
6053 tools that help users exert that freedom.
6055 Packages are currently available on the following platforms:
6060 Intel/AMD @code{x86_64} architecture, Linux-Libre kernel;
6063 Intel 32-bit architecture (IA32), Linux-Libre kernel;
6066 ARMv7-A architecture with hard float, Thumb-2 and NEON,
6067 using the EABI hard-float application binary interface (ABI),
6068 and Linux-Libre kernel.
6070 @item mips64el-linux
6071 little-endian 64-bit MIPS processors, specifically the Loongson series,
6072 n32 ABI, and Linux-Libre kernel.
6076 GuixSD itself is currently only available on @code{i686} and @code{x86_64}.
6079 For information on porting to other architectures or kernels,
6083 * System Installation:: Installing the whole operating system.
6084 * System Configuration:: Configuring the operating system.
6085 * Installing Debugging Files:: Feeding the debugger.
6086 * Security Updates:: Deploying security fixes quickly.
6087 * Package Modules:: Packages from the programmer's viewpoint.
6088 * Packaging Guidelines:: Growing the distribution.
6089 * Bootstrapping:: GNU/Linux built from scratch.
6090 * Porting:: Targeting another platform or kernel.
6093 Building this distribution is a cooperative effort, and you are invited
6094 to join! @xref{Contributing}, for information about how you can help.
6096 @node System Installation
6097 @section System Installation
6099 @cindex Guix System Distribution
6100 This section explains how to install the Guix System Distribution (GuixSD)
6101 on a machine. The Guix package manager can
6102 also be installed on top of a running GNU/Linux system,
6103 @pxref{Installation}.
6107 @c This paragraph is for people reading this from tty2 of the
6108 @c installation image.
6109 You are reading this documentation with an Info reader. For details on
6110 how to use it, hit the @key{RET} key (``return'' or ``enter'') on the
6111 link that follows: @pxref{Top, Info reader,, info-stnd, Stand-alone GNU
6112 Info}. Hit @kbd{l} afterwards to come back here.
6114 Alternately, run @command{info info} in another tty to keep the manual
6120 * Limitations:: What you can expect.
6121 * Hardware Considerations:: Supported hardware.
6122 * USB Stick Installation:: Preparing the installation medium.
6123 * Preparing for Installation:: Networking, partitioning, etc.
6124 * Proceeding with the Installation:: The real thing.
6125 * Installing GuixSD in a VM:: GuixSD playground.
6126 * Building the Installation Image:: How this comes to be.
6130 @subsection Limitations
6132 As of version @value{VERSION}, the Guix System Distribution (GuixSD) is
6133 not production-ready. It may contain bugs and lack important
6134 features. Thus, if you are looking for a stable production system that
6135 respects your freedom as a computer user, a good solution at this point
6136 is to consider @url{http://www.gnu.org/distros/free-distros.html, one of
6137 the more established GNU/Linux distributions}. We hope you can soon switch
6138 to the GuixSD without fear, of course. In the meantime, you can
6139 also keep using your distribution and try out the package manager on top
6140 of it (@pxref{Installation}).
6142 Before you proceed with the installation, be aware of the following
6143 noteworthy limitations applicable to version @value{VERSION}:
6147 The installation process does not include a graphical user interface and
6148 requires familiarity with GNU/Linux (see the following subsections to
6149 get a feel of what that means.)
6152 Support for the Logical Volume Manager (LVM) is missing.
6155 Few system services are currently supported out-of-the-box
6159 More than 3,200 packages are available, but you may
6160 occasionally find that a useful package is missing.
6163 GNOME, Xfce, and Enlightenment are available (@pxref{Desktop Services}),
6164 as well as a number of X11 window managers. However, some graphical
6165 applications may be missing, as well as KDE.
6168 You have been warned! But more than a disclaimer, this is an invitation
6169 to report issues (and success stories!), and to join us in improving it.
6170 @xref{Contributing}, for more info.
6173 @node Hardware Considerations
6174 @subsection Hardware Considerations
6176 @cindex hardware support on GuixSD
6177 GNU@tie{}GuixSD focuses on respecting the user's computing freedom. It
6178 builds around the kernel Linux-libre, which means that only hardware for
6179 which free software drivers and firmware exist is supported. Nowadays,
6180 a wide range of off-the-shelf hardware is supported on
6181 GNU/Linux-libre---from keyboards to graphics cards to scanners and
6182 Ethernet controllers. Unfortunately, there are still areas where
6183 hardware vendors deny users control over their own computing, and such
6184 hardware is not supported on GuixSD.
6186 @cindex WiFi, hardware support
6187 One of the main areas where free drivers or firmware are lacking is WiFi
6188 devices. WiFi devices known to work include those using Atheros chips
6189 (AR9271 and AR7010), which corresponds to the @code{ath9k} Linux-libre
6190 driver, and for which free firmware exists and is available
6191 out-of-the-box on GuixSD, as part of @var{%base-firmware}
6192 (@pxref{operating-system Reference, @code{firmware}}).
6194 @cindex RYF, Respects Your Freedom
6195 The @uref{https://www.fsf.org/, Free Software Foundation} runs
6196 @uref{https://www.fsf.org/ryf, @dfn{Respects Your Freedom}} (RYF), a
6197 certification program for hardware products that respect your freedom
6198 and your privacy and ensure that you have control over your device. We
6199 encourage you to check the list of RYF-certified devices.
6201 Another useful resource is the @uref{https://www.h-node.org/, H-Node}
6202 web site. It contains a catalog of hardware devices with information
6203 about their support in GNU/Linux.
6206 @node USB Stick Installation
6207 @subsection USB Stick Installation
6209 An installation image for USB sticks can be downloaded from
6210 @indicateurl{ftp://alpha.gnu.org/gnu/guix/guixsd-usb-install-@value{VERSION}.@var{system}.xz},
6211 where @var{system} is one of:
6215 for a GNU/Linux system on Intel/AMD-compatible 64-bit CPUs;
6218 for a 32-bit GNU/Linux system on Intel-compatible CPUs.
6221 @c start duplication of authentication part from ``Binary Installation''
6222 Make sure to download the associated @file{.sig} file and to verify the
6223 authenticity of the image against it, along these lines:
6226 $ wget ftp://alpha.gnu.org/gnu/guix/guixsd-usb-install-@value{VERSION}.@var{system}.xz.sig
6227 $ gpg --verify guixsd-usb-install-@value{VERSION}.@var{system}.xz.sig
6230 If that command fails because you do not have the required public key,
6231 then run this command to import it:
6234 $ gpg --keyserver pgp.mit.edu --recv-keys @value{OPENPGP-SIGNING-KEY-ID}
6238 and rerun the @code{gpg --verify} command.
6241 This image contains a single partition with the tools necessary for an
6242 installation. It is meant to be copied @emph{as is} to a large-enough
6245 To copy the image to a USB stick, follow these steps:
6249 Decompress the image using the @command{xz} command:
6252 xz -d guixsd-usb-install-@value{VERSION}.@var{system}.xz
6256 Insert a USB stick of 1@tie{}GiB or more into your machine, and determine
6257 its device name. Assuming that the USB stick is known as @file{/dev/sdX},
6258 copy the image with:
6261 dd if=guixsd-usb-install-@value{VERSION}.x86_64 of=/dev/sdX
6264 Access to @file{/dev/sdX} usually requires root privileges.
6267 Once this is done, you should be able to reboot the system and boot from
6268 the USB stick. The latter usually requires you to get in the BIOS' boot
6269 menu, where you can choose to boot from the USB stick.
6271 @xref{Installing GuixSD in a VM}, if, instead, you would like to install
6272 GuixSD in a virtual machine (VM).
6274 @node Preparing for Installation
6275 @subsection Preparing for Installation
6277 Once you have successfully booted the image on the USB stick, you should
6278 end up with a root prompt. Several console TTYs are configured and can
6279 be used to run commands as root. TTY2 shows this documentation,
6280 browsable using the Info reader commands (@pxref{Top,,, info-stnd,
6281 Stand-alone GNU Info}). The installation system runs the GPM mouse
6282 daemon, which allows you to select text with the left mouse button and
6283 to paste it with the middle button.
6286 Installation requires access to the Internet so that any missing
6287 dependencies of your system configuration can be downloaded. See the
6288 ``Networking'' section below.
6291 The installation system includes many common tools needed for this task.
6292 But it is also a full-blown GuixSD system, which means that you can
6293 install additional packages, should you need it, using @command{guix
6294 package} (@pxref{Invoking guix package}).
6296 @subsubsection Keyboard Layout
6298 @cindex keyboard layout
6299 The installation image uses the US qwerty keyboard layout. If you want
6300 to change it, you can use the @command{loadkeys} command. For example,
6301 the following command selects the Dvorak keyboard layout:
6307 See the files under @file{/run/current-system/profile/share/keymaps} for
6308 a list of available keyboard layouts. Run @command{man loadkeys} for
6311 @subsubsection Networking
6313 Run the following command see what your network interfaces are called:
6320 @dots{} or, using the GNU/Linux-specific @command{ip} command:
6326 @c http://cgit.freedesktop.org/systemd/systemd/tree/src/udev/udev-builtin-net_id.c#n20
6327 Wired interfaces have a name starting with @samp{e}; for example, the
6328 interface corresponding to the first on-board Ethernet controller is
6329 called @samp{eno1}. Wireless interfaces have a name starting with
6330 @samp{w}, like @samp{w1p2s0}.
6333 @item Wired connection
6334 To configure a wired network run the following command, substituting
6335 @var{interface} with the name of the wired interface you want to use.
6338 ifconfig @var{interface} up
6341 @item Wireless connection
6342 To configure wireless networking, you can create a configuration file
6343 for the @command{wpa_supplicant} configuration tool (its location is not
6344 important) using one of the available text editors such as
6348 zile wpa_supplicant.conf
6351 As an example, the following stanza can go to this file and will work
6352 for many wireless networks, provided you give the actual SSID and
6353 passphrase for the network you are connecting to:
6357 ssid="@var{my-ssid}"
6359 psk="the network's secret passphrase"
6363 Start the wireless service and run it in the background with the
6364 following command (substitute @var{interface} with the name of the
6365 network interface you want to use):
6368 wpa_supplicant -c wpa_supplicant.conf -i @var{interface} -B
6371 Run @command{man wpa_supplicant} for more information.
6374 At this point, you need to acquire an IP address. On a network where IP
6375 addresses are automatically assigned @i{via} DHCP, you can run:
6378 dhclient -v @var{interface}
6381 Try to ping a server to see if networking is up and running:
6387 Setting up network access is almost always a requirement because the
6388 image does not contain all the software and tools that may be needed.
6390 @subsubsection Disk Partitioning
6392 Unless this has already been done, the next step is to partition, and
6393 then format the target partition(s).
6395 The installation image includes several partitioning tools, including
6396 Parted (@pxref{Overview,,, parted, GNU Parted User Manual}),
6397 @command{fdisk}, and @command{cfdisk}. Run it and set up your disk with
6398 the partition layout you want:
6404 Once you are done partitioning the target hard disk drive, you have to
6405 create a file system on the relevant partition(s)@footnote{Currently
6406 GuixSD pretty much assumes an ext4 file system. In particular, code
6407 that reads partition UUIDs and labels only works with ext4. This will
6408 be fixed in the future.}.
6410 Preferably, assign partitions a label so that you can easily and
6411 reliably refer to them in @code{file-system} declarations (@pxref{File
6412 Systems}). This is typically done using the @code{-L} option of
6413 @command{mkfs.ext4} and related commands. So, assuming the target root
6414 partition lives at @file{/dev/sda1}, a file system with the label
6415 @code{my-root} can be created with:
6418 mkfs.ext4 -L my-root /dev/sda1
6421 @c FIXME: Uncomment this once GRUB fully supports encrypted roots.
6422 @c A typical command sequence may be:
6426 @c @dots{} Create partitions etc.@dots{}
6427 @c # cryptsetup luksFormat /dev/sdX1
6428 @c # cryptsetup open --type luks /dev/sdX1 my-partition
6429 @c # mkfs.ext4 -L my-root /dev/mapper/my-partition
6432 In addition to e2fsprogs, the suite of tools to manipulate
6433 ext2/ext3/ext4 file systems, the installation image includes
6434 Cryptsetup/LUKS for disk encryption.
6436 Once that is done, mount the target root partition under @file{/mnt}
6437 with a command like (again, assuming @file{/dev/sda1} is the root
6441 mount /dev/sda1 /mnt
6444 Finally, if you plan to use one or more swap partitions (@pxref{Memory
6445 Concepts, swap space,, libc, The GNU C Library Reference Manual}), make
6446 sure to initialize them with @command{mkswap}. Assuming you have one
6447 swap partition on @file{/dev/sda2}, you would run:
6453 @node Proceeding with the Installation
6454 @subsection Proceeding with the Installation
6456 With the target partitions ready and the target root mounted on
6457 @file{/mnt}, we're ready to go. First, run:
6460 herd start cow-store /mnt
6463 This makes @file{/gnu/store} copy-on-write, such that packages added to it
6464 during the installation phase are written to the target disk on @file{/mnt}
6465 rather than kept in memory. This is necessary because the first phase of
6466 the @command{guix system init} command (see below) entails downloads or
6467 builds to @file{/gnu/store} which, initially, is an in-memory file system.
6469 Next, you have to edit a file and
6470 provide the declaration of the operating system to be installed. To
6471 that end, the installation system comes with three text editors: GNU nano
6472 (@pxref{Top,,, nano, GNU nano Manual}), GNU Zile (an Emacs clone), and
6473 nvi (a clone of the original BSD @command{vi} editor).
6474 We strongly recommend storing that file on the target root file system, say,
6475 as @file{/mnt/etc/config.scm}. Failing to do that, you will have lost your
6476 configuration file once you have rebooted into the newly-installed system.
6478 @xref{Using the Configuration System}, for an overview of the
6479 configuration file. The example configurations discussed in that
6480 section are available under @file{/etc/configuration} in the
6481 installation image. Thus, to get started with a system configuration
6482 providing a graphical display server (a ``desktop'' system), you can run
6483 something along these lines:
6487 # cp /etc/configuration/desktop.scm /mnt/etc/config.scm
6488 # zile /mnt/etc/config.scm
6491 You should pay attention to what your configuration file contains, and
6496 Make sure the @code{grub-configuration} form refers to the device you
6497 want to install GRUB on.
6500 Be sure that your partition labels match the value of their respective
6501 @code{device} fields in your @code{file-system} configuration, assuming
6502 your @code{file-system} configuration sets the value of @code{title} to
6506 Once you are done preparing the configuration file, the new system must
6507 be initialized (remember that the target root file system is mounted
6511 guix system init /mnt/etc/config.scm /mnt
6515 This copies all the necessary files and installs GRUB on
6516 @file{/dev/sdX}, unless you pass the @option{--no-grub} option. For
6517 more information, @pxref{Invoking guix system}. This command may trigger
6518 downloads or builds of missing packages, which can take some time.
6520 Once that command has completed---and hopefully succeeded!---you can run
6521 @command{reboot} and boot into the new system. The @code{root} password
6522 in the new system is initially empty; other users' passwords need to be
6523 initialized by running the @command{passwd} command as @code{root},
6524 unless your configuration specifies otherwise
6525 (@pxref{user-account-password, user account passwords}).
6527 Join us on @code{#guix} on the Freenode IRC network or on
6528 @file{guix-devel@@gnu.org} to share your experience---good or not so
6531 @node Installing GuixSD in a VM
6532 @subsection Installing GuixSD in a Virtual Machine
6534 @cindex virtual machine, GuixSD installation
6535 If you'd like to install GuixSD in a virtual machine (VM) rather than on
6536 your beloved machine, this section is for you.
6538 To boot a @uref{http://qemu.org/,QEMU} VM for installing GuixSD in a
6539 disk image, follow these steps:
6543 First, retrieve the GuixSD installation image as described previously
6544 (@pxref{USB Stick Installation}).
6547 Create a disk image that will hold the installed system. To make a
6548 qcow2-formatted disk image, use the @command{qemu-img} command:
6551 qemu-img create -f qcow2 guixsd.img 5G
6554 This will create a 5GB file.
6557 Boot the USB installation image in an VM:
6560 qemu-system-x86_64 -m 1024 -smp 1 \
6561 -net default -net nic,model=virtio -boot menu=on \
6562 -drive file=guixsd.img \
6563 -drive file=guixsd-usb-install-@value{VERSION}.@var{system}
6566 In the VM console, quickly press the @kbd{F12} key to enter the boot
6567 menu. Then press the @kbd{2} key and the @kbd{RET} key to validate your
6571 You're now root in the VM, proceed with the installation process.
6572 @xref{Preparing for Installation}, and follow the instructions.
6575 Once installation is complete, you can boot the system that's on your
6576 @file{guixsd.img} image. @xref{Running GuixSD in a VM}, for how to do
6579 @node Building the Installation Image
6580 @subsection Building the Installation Image
6582 The installation image described above was built using the @command{guix
6583 system} command, specifically:
6585 @c FIXME: 1G is too much; see <http://bugs.gnu.org/23077>.
6587 guix system disk-image --image-size=1G gnu/system/install.scm
6590 Have a look at @file{gnu/system/install.scm} in the source tree,
6591 and see also @ref{Invoking guix system} for more information
6592 about the installation image.
6594 @node System Configuration
6595 @section System Configuration
6597 @cindex system configuration
6598 The Guix System Distribution supports a consistent whole-system configuration
6599 mechanism. By that we mean that all aspects of the global system
6600 configuration---such as the available system services, timezone and
6601 locale settings, user accounts---are declared in a single place. Such
6602 a @dfn{system configuration} can be @dfn{instantiated}---i.e., effected.
6604 One of the advantages of putting all the system configuration under the
6605 control of Guix is that it supports transactional system upgrades, and
6606 makes it possible to roll back to a previous system instantiation,
6607 should something go wrong with the new one (@pxref{Features}). Another
6608 advantage is that it makes it easy to replicate the exact same configuration
6609 across different machines, or at different points in time, without
6610 having to resort to additional administration tools layered on top of
6611 the own tools of the system.
6612 @c Yes, we're talking of Puppet, Chef, & co. here. ↑
6614 This section describes this mechanism. First we focus on the system
6615 administrator's viewpoint---explaining how the system is configured and
6616 instantiated. Then we show how this mechanism can be extended, for
6617 instance to support new system services.
6620 * Using the Configuration System:: Customizing your GNU system.
6621 * operating-system Reference:: Detail of operating-system declarations.
6622 * File Systems:: Configuring file system mounts.
6623 * Mapped Devices:: Block device extra processing.
6624 * User Accounts:: Specifying user accounts.
6625 * Locales:: Language and cultural convention settings.
6626 * Services:: Specifying system services.
6627 * Setuid Programs:: Programs running with root privileges.
6628 * X.509 Certificates:: Authenticating HTTPS servers.
6629 * Name Service Switch:: Configuring libc's name service switch.
6630 * Initial RAM Disk:: Linux-Libre bootstrapping.
6631 * GRUB Configuration:: Configuring the boot loader.
6632 * Invoking guix system:: Instantiating a system configuration.
6633 * Running GuixSD in a VM:: How to run GuixSD in a virtual machine.
6634 * Defining Services:: Adding new service definitions.
6637 @node Using the Configuration System
6638 @subsection Using the Configuration System
6640 The operating system is configured by providing an
6641 @code{operating-system} declaration in a file that can then be passed to
6642 the @command{guix system} command (@pxref{Invoking guix system}). A
6643 simple setup, with the default system services, the default Linux-Libre
6644 kernel, initial RAM disk, and boot loader looks like this:
6646 @findex operating-system
6648 @include os-config-bare-bones.texi
6651 This example should be self-describing. Some of the fields defined
6652 above, such as @code{host-name} and @code{bootloader}, are mandatory.
6653 Others, such as @code{packages} and @code{services}, can be omitted, in
6654 which case they get a default value.
6656 Below we discuss the effect of some of the most important fields
6657 (@pxref{operating-system Reference}, for details about all the available
6658 fields), and how to @dfn{instantiate} the operating system using
6659 @command{guix system}.
6661 @unnumberedsubsubsec Globally-Visible Packages
6663 @vindex %base-packages
6664 The @code{packages} field lists packages that will be globally visible
6665 on the system, for all user accounts---i.e., in every user's @code{PATH}
6666 environment variable---in addition to the per-user profiles
6667 (@pxref{Invoking guix package}). The @var{%base-packages} variable
6668 provides all the tools one would expect for basic user and administrator
6669 tasks---including the GNU Core Utilities, the GNU Networking Utilities,
6670 the GNU Zile lightweight text editor, @command{find}, @command{grep},
6671 etc. The example above adds tcpdump to those, taken from the @code{(gnu
6672 packages admin)} module (@pxref{Package Modules}).
6674 @findex specification->package
6675 Referring to packages by variable name, like @var{tcpdump} above, has
6676 the advantage of being unambiguous; it also allows typos and such to be
6677 diagnosed right away as ``unbound variables''. The downside is that one
6678 needs to know which module defines which package, and to augment the
6679 @code{use-package-modules} line accordingly. To avoid that, one can use
6680 the @code{specification->package} procedure of the @code{(gnu packages)}
6681 module, which returns the best package for a given name or name and
6685 (use-modules (gnu packages))
6689 (packages (append (map specification->package
6690 '("tcpdump" "htop" "gnupg@@2.0"))
6694 @unnumberedsubsubsec System Services
6696 @vindex %base-services
6697 The @code{services} field lists @dfn{system services} to be made
6698 available when the system starts (@pxref{Services}).
6699 The @code{operating-system} declaration above specifies that, in
6700 addition to the basic services, we want the @command{lshd} secure shell
6701 daemon listening on port 2222 (@pxref{Networking Services,
6702 @code{lsh-service}}). Under the hood,
6703 @code{lsh-service} arranges so that @code{lshd} is started with the
6704 right command-line options, possibly with supporting configuration files
6705 generated as needed (@pxref{Defining Services}).
6707 @cindex customization, of services
6708 @findex modify-services
6709 Occasionally, instead of using the base services as is, you will want to
6710 customize them. To do this, use @code{modify-services} (@pxref{Service
6711 Reference, @code{modify-services}}) to modify the list.
6713 For example, suppose you want to modify @code{guix-daemon} and Mingetty
6714 (the console log-in) in the @var{%base-services} list (@pxref{Base
6715 Services, @code{%base-services}}). To do that, you can write the
6716 following in your operating system declaration:
6719 (define %my-services
6720 ;; My very own list of services.
6721 (modify-services %base-services
6722 (guix-service-type config =>
6725 (use-substitutes? #f)
6726 (extra-options '("--gc-keep-derivations"))))
6727 (mingetty-service-type config =>
6728 (mingetty-configuration
6730 (motd (plain-file "motd" "Howdy!"))))))
6734 (services %my-services))
6737 This changes the configuration---i.e., the service parameters---of the
6738 @code{guix-service-type} instance, and that of all the
6739 @code{mingetty-service-type} instances in the @var{%base-services} list.
6740 Observe how this is accomplished: first, we arrange for the original
6741 configuration to be bound to the identifier @code{config} in the
6742 @var{body}, and then we write the @var{body} so that it evaluates to the
6743 desired configuration. In particular, notice how we use @code{inherit}
6744 to create a new configuration which has the same values as the old
6745 configuration, but with a few modifications.
6747 The configuration for a typical ``desktop'' usage, with the X11 display
6748 server, GNOME and Xfce (users can choose which of these desktop
6749 environments to use at the log-in screen by pressing @kbd{F1}), network
6750 management, power management, and more, would look like this:
6753 @include os-config-desktop.texi
6756 A graphical environment with a choice of lightweight window managers
6757 instead of full-blown desktop environments would look like this:
6760 @include os-config-lightweight-desktop.texi
6763 @xref{Desktop Services}, for the exact list of services provided by
6764 @var{%desktop-services}. @xref{X.509 Certificates}, for background
6765 information about the @code{nss-certs} package that is used here.
6767 Again, @var{%desktop-services} is just a list of service objects. If
6768 you want to remove services from there, you can do so using the
6769 procedures for list filtering (@pxref{SRFI-1 Filtering and
6770 Partitioning,,, guile, GNU Guile Reference Manual}). For instance, the
6771 following expression returns a list that contains all the services in
6772 @var{%desktop-services} minus the Avahi service:
6775 (remove (lambda (service)
6776 (eq? (service-kind service) avahi-service-type))
6780 @unnumberedsubsubsec Instantiating the System
6782 Assuming the @code{operating-system} declaration
6783 is stored in the @file{my-system-config.scm}
6784 file, the @command{guix system reconfigure my-system-config.scm} command
6785 instantiates that configuration, and makes it the default GRUB boot
6786 entry (@pxref{Invoking guix system}).
6788 The normal way to change the system configuration is by updating this
6789 file and re-running @command{guix system reconfigure}. One should never
6790 have to touch files in @command{/etc} or to run commands that modify the
6791 system state such as @command{useradd} or @command{grub-install}. In
6792 fact, you must avoid that since that would not only void your warranty
6793 but also prevent you from rolling back to previous versions of your
6794 system, should you ever need to.
6796 @cindex roll-back, of the operating system
6797 Speaking of roll-back, each time you run @command{guix system
6798 reconfigure}, a new @dfn{generation} of the system is created---without
6799 modifying or deleting previous generations. Old system generations get
6800 an entry in the GRUB boot menu, allowing you to boot them in case
6801 something went wrong with the latest generation. Reassuring, no? The
6802 @command{guix system list-generations} command lists the system
6803 generations available on disk.
6805 @unnumberedsubsubsec The Programming Interface
6807 At the Scheme level, the bulk of an @code{operating-system} declaration
6808 is instantiated with the following monadic procedure (@pxref{The Store
6811 @deffn {Monadic Procedure} operating-system-derivation os
6812 Return a derivation that builds @var{os}, an @code{operating-system}
6813 object (@pxref{Derivations}).
6815 The output of the derivation is a single directory that refers to all
6816 the packages, configuration files, and other supporting files needed to
6817 instantiate @var{os}.
6820 This procedure is provided by the @code{(gnu system)} module. Along
6821 with @code{(gnu services)} (@pxref{Services}), this module contains the
6822 guts of GuixSD. Make sure to visit it!
6825 @node operating-system Reference
6826 @subsection @code{operating-system} Reference
6828 This section summarizes all the options available in
6829 @code{operating-system} declarations (@pxref{Using the Configuration
6832 @deftp {Data Type} operating-system
6833 This is the data type representing an operating system configuration.
6834 By that, we mean all the global system configuration, not per-user
6835 configuration (@pxref{Using the Configuration System}).
6838 @item @code{kernel} (default: @var{linux-libre})
6839 The package object of the operating system kernel to use@footnote{Currently
6840 only the Linux-libre kernel is supported. In the future, it will be
6841 possible to use the GNU@tie{}Hurd.}.
6843 @item @code{kernel-arguments} (default: @code{'()})
6844 List of strings or gexps representing additional arguments to pass on
6845 the command-line of the kernel---e.g., @code{("console=ttyS0")}.
6847 @item @code{bootloader}
6848 The system bootloader configuration object. @xref{GRUB Configuration}.
6850 @item @code{initrd} (default: @code{base-initrd})
6851 A two-argument monadic procedure that returns an initial RAM disk for
6852 the Linux kernel. @xref{Initial RAM Disk}.
6854 @item @code{firmware} (default: @var{%base-firmware})
6856 List of firmware packages loadable by the operating system kernel.
6858 The default includes firmware needed for Atheros-based WiFi devices
6859 (Linux-libre module @code{ath9k}). @xref{Hardware Considerations}, for
6860 more info on supported hardware.
6862 @item @code{host-name}
6865 @item @code{hosts-file}
6867 A file-like object (@pxref{G-Expressions, file-like objects}) for use as
6868 @file{/etc/hosts} (@pxref{Host Names,,, libc, The GNU C Library
6869 Reference Manual}). The default is a file with entries for
6870 @code{localhost} and @var{host-name}.
6872 @item @code{mapped-devices} (default: @code{'()})
6873 A list of mapped devices. @xref{Mapped Devices}.
6875 @item @code{file-systems}
6876 A list of file systems. @xref{File Systems}.
6878 @item @code{swap-devices} (default: @code{'()})
6879 @cindex swap devices
6880 A list of strings identifying devices to be used for ``swap space''
6881 (@pxref{Memory Concepts,,, libc, The GNU C Library Reference Manual}).
6882 For example, @code{'("/dev/sda3")}.
6884 @item @code{users} (default: @code{%base-user-accounts})
6885 @itemx @code{groups} (default: @var{%base-groups})
6886 List of user accounts and groups. @xref{User Accounts}.
6888 @item @code{skeletons} (default: @code{(default-skeletons)})
6889 A list target file name/file-like object tuples (@pxref{G-Expressions,
6890 file-like objects}). These are the skeleton files that will be added to
6891 the home directory of newly-created user accounts.
6893 For instance, a valid value may look like this:
6896 `((".bashrc" ,(plain-file "bashrc" "echo Hello\n"))
6897 (".guile" ,(plain-file "guile"
6898 "(use-modules (ice-9 readline))
6899 (activate-readline)")))
6902 @item @code{issue} (default: @var{%default-issue})
6903 A string denoting the contents of the @file{/etc/issue} file, which is
6904 displayed when users log in on a text console.
6906 @item @code{packages} (default: @var{%base-packages})
6907 The set of packages installed in the global profile, which is accessible
6908 at @file{/run/current-system/profile}.
6910 The default set includes core utilities and it is good practice to
6911 install non-core utilities in user profiles (@pxref{Invoking guix
6914 @item @code{timezone}
6915 A timezone identifying string---e.g., @code{"Europe/Paris"}.
6917 You can run the @command{tzselect} command to find out which timezone
6918 string corresponds to your region. Choosing an invalid timezone name
6919 causes @command{guix system} to fail.
6921 @item @code{locale} (default: @code{"en_US.utf8"})
6922 The name of the default locale (@pxref{Locale Names,,, libc, The GNU C
6923 Library Reference Manual}). @xref{Locales}, for more information.
6925 @item @code{locale-definitions} (default: @var{%default-locale-definitions})
6926 The list of locale definitions to be compiled and that may be used at
6927 run time. @xref{Locales}.
6929 @item @code{locale-libcs} (default: @code{(list @var{glibc})})
6930 The list of GNU@tie{}libc packages whose locale data and tools are used
6931 to build the locale definitions. @xref{Locales}, for compatibility
6932 considerations that justify this option.
6934 @item @code{name-service-switch} (default: @var{%default-nss})
6935 Configuration of the libc name service switch (NSS)---a
6936 @code{<name-service-switch>} object. @xref{Name Service Switch}, for
6939 @item @code{services} (default: @var{%base-services})
6940 A list of service objects denoting system services. @xref{Services}.
6942 @item @code{pam-services} (default: @code{(base-pam-services)})
6944 @cindex pluggable authentication modules
6945 Linux @dfn{pluggable authentication module} (PAM) services.
6946 @c FIXME: Add xref to PAM services section.
6948 @item @code{setuid-programs} (default: @var{%setuid-programs})
6949 List of string-valued G-expressions denoting setuid programs.
6950 @xref{Setuid Programs}.
6952 @item @code{sudoers-file} (default: @var{%sudoers-specification})
6953 @cindex sudoers file
6954 The contents of the @file{/etc/sudoers} file as a file-like object
6955 (@pxref{G-Expressions, @code{local-file} and @code{plain-file}}).
6957 This file specifies which users can use the @command{sudo} command, what
6958 they are allowed to do, and what privileges they may gain. The default
6959 is that only @code{root} and members of the @code{wheel} group may use
6966 @subsection File Systems
6968 The list of file systems to be mounted is specified in the
6969 @code{file-systems} field of the operating system declaration
6970 (@pxref{Using the Configuration System}). Each file system is declared
6971 using the @code{file-system} form, like this:
6975 (mount-point "/home")
6976 (device "/dev/sda3")
6980 As usual, some of the fields are mandatory---those shown in the example
6981 above---while others can be omitted. These are described below.
6983 @deftp {Data Type} file-system
6984 Objects of this type represent file systems to be mounted. They
6985 contain the following members:
6989 This is a string specifying the type of the file system---e.g.,
6992 @item @code{mount-point}
6993 This designates the place where the file system is to be mounted.
6996 This names the ``source'' of the file system. By default it is the name
6997 of a node under @file{/dev}, but its meaning depends on the @code{title}
6998 field described below.
7000 @item @code{title} (default: @code{'device})
7001 This is a symbol that specifies how the @code{device} field is to be
7004 When it is the symbol @code{device}, then the @code{device} field is
7005 interpreted as a file name; when it is @code{label}, then @code{device}
7006 is interpreted as a partition label name; when it is @code{uuid},
7007 @code{device} is interpreted as a partition unique identifier (UUID).
7009 UUIDs may be converted from their string representation (as shown by the
7010 @command{tune2fs -l} command) using the @code{uuid} form@footnote{The
7011 @code{uuid} form expects 16-byte UUIDs as defined in
7012 @uref{https://tools.ietf.org/html/rfc4122, RFC@tie{}4122}. This is the
7013 form of UUID used by the ext2 family of file systems and others, but it
7014 is different from ``UUIDs'' found in FAT file systems, for instance.},
7019 (mount-point "/home")
7022 (device (uuid "4dab5feb-d176-45de-b287-9b0a6e4c01cb")))
7025 The @code{label} and @code{uuid} options offer a way to refer to disk
7026 partitions without having to hard-code their actual device
7027 name@footnote{Note that, while it is tempting to use
7028 @file{/dev/disk/by-uuid} and similar device names to achieve the same
7029 result, this is not recommended: These special device nodes are created
7030 by the udev daemon and may be unavailable at the time the device is
7033 However, when the source of a file system is a mapped device (@pxref{Mapped
7034 Devices}), its @code{device} field @emph{must} refer to the mapped
7035 device name---e.g., @file{/dev/mapper/root-partition}---and consequently
7036 @code{title} must be set to @code{'device}. This is required so that
7037 the system knows that mounting the file system depends on having the
7038 corresponding device mapping established.
7040 @item @code{flags} (default: @code{'()})
7041 This is a list of symbols denoting mount flags. Recognized flags
7042 include @code{read-only}, @code{bind-mount}, @code{no-dev} (disallow
7043 access to special files), @code{no-suid} (ignore setuid and setgid
7044 bits), and @code{no-exec} (disallow program execution.)
7046 @item @code{options} (default: @code{#f})
7047 This is either @code{#f}, or a string denoting mount options.
7049 @item @code{mount?} (default: @code{#t})
7050 This value indicates whether to automatically mount the file system when
7051 the system is brought up. When set to @code{#f}, the file system gets
7052 an entry in @file{/etc/fstab} (read by the @command{mount} command) but
7053 is not automatically mounted.
7055 @item @code{needed-for-boot?} (default: @code{#f})
7056 This Boolean value indicates whether the file system is needed when
7057 booting. If that is true, then the file system is mounted when the
7058 initial RAM disk (initrd) is loaded. This is always the case, for
7059 instance, for the root file system.
7061 @item @code{check?} (default: @code{#t})
7062 This Boolean indicates whether the file system needs to be checked for
7063 errors before being mounted.
7065 @item @code{create-mount-point?} (default: @code{#f})
7066 When true, the mount point is created if it does not exist yet.
7068 @item @code{dependencies} (default: @code{'()})
7069 This is a list of @code{<file-system>} objects representing file systems
7070 that must be mounted before (and unmounted after) this one.
7072 As an example, consider a hierarchy of mounts: @file{/sys/fs/cgroup} is
7073 a dependency of @file{/sys/fs/cgroup/cpu} and
7074 @file{/sys/fs/cgroup/memory}.
7079 The @code{(gnu system file-systems)} exports the following useful
7082 @defvr {Scheme Variable} %base-file-systems
7083 These are essential file systems that are required on normal systems,
7084 such as @var{%pseudo-terminal-file-system} and @var{%immutable-store} (see
7085 below.) Operating system declarations should always contain at least
7089 @defvr {Scheme Variable} %pseudo-terminal-file-system
7090 This is the file system to be mounted as @file{/dev/pts}. It supports
7091 @dfn{pseudo-terminals} created @i{via} @code{openpty} and similar
7092 functions (@pxref{Pseudo-Terminals,,, libc, The GNU C Library Reference
7093 Manual}). Pseudo-terminals are used by terminal emulators such as
7097 @defvr {Scheme Variable} %shared-memory-file-system
7098 This file system is mounted as @file{/dev/shm} and is used to support
7099 memory sharing across processes (@pxref{Memory-mapped I/O,
7100 @code{shm_open},, libc, The GNU C Library Reference Manual}).
7103 @defvr {Scheme Variable} %immutable-store
7104 This file system performs a read-only ``bind mount'' of
7105 @file{/gnu/store}, making it read-only for all the users including
7106 @code{root}. This prevents against accidental modification by software
7107 running as @code{root} or by system administrators.
7109 The daemon itself is still able to write to the store: it remounts it
7110 read-write in its own ``name space.''
7113 @defvr {Scheme Variable} %binary-format-file-system
7114 The @code{binfmt_misc} file system, which allows handling of arbitrary
7115 executable file types to be delegated to user space. This requires the
7116 @code{binfmt.ko} kernel module to be loaded.
7119 @defvr {Scheme Variable} %fuse-control-file-system
7120 The @code{fusectl} file system, which allows unprivileged users to mount
7121 and unmount user-space FUSE file systems. This requires the
7122 @code{fuse.ko} kernel module to be loaded.
7125 @node Mapped Devices
7126 @subsection Mapped Devices
7128 @cindex device mapping
7129 @cindex mapped devices
7130 The Linux kernel has a notion of @dfn{device mapping}: a block device,
7131 such as a hard disk partition, can be @dfn{mapped} into another device,
7132 usually in @code{/dev/mapper/},
7133 with additional processing over the data that flows through
7134 it@footnote{Note that the GNU@tie{}Hurd makes no difference between the
7135 concept of a ``mapped device'' and that of a file system: both boil down
7136 to @emph{translating} input/output operations made on a file to
7137 operations on its backing store. Thus, the Hurd implements mapped
7138 devices, like file systems, using the generic @dfn{translator} mechanism
7139 (@pxref{Translators,,, hurd, The GNU Hurd Reference Manual}).}. A
7140 typical example is encryption device mapping: all writes to the mapped
7141 device are encrypted, and all reads are deciphered, transparently.
7142 Guix extends this notion by considering any device or set of devices that
7143 are @dfn{transformed} in some way to create a new device; for instance,
7144 RAID devices are obtained by @dfn{assembling} several other devices, such
7145 as hard disks or partitions, into a new one that behaves as one partition.
7146 Other examples, not yet implemented, are LVM logical volumes.
7148 Mapped devices are declared using the @code{mapped-device} form,
7149 defined as follows; for examples, see below.
7151 @deftp {Data Type} mapped-device
7152 Objects of this type represent device mappings that will be made when
7153 the system boots up.
7157 This is either a string specifying the name of the block device to be mapped,
7158 such as @code{"/dev/sda3"}, or a list of such strings when several devices
7159 need to be assembled for creating a new one.
7162 This string specifies the name of the resulting mapped device. For
7163 kernel mappers such as encrypted devices of type @code{luks-device-mapping},
7164 specifying @code{"my-partition"} leads to the creation of
7165 the @code{"/dev/mapper/my-partition"} device.
7166 For RAID devices of type @code{raid-device-mapping}, the full device name
7167 such as @code{"/dev/md0"} needs to be given.
7170 This must be a @code{mapped-device-kind} object, which specifies how
7171 @var{source} is mapped to @var{target}.
7175 @defvr {Scheme Variable} luks-device-mapping
7176 This defines LUKS block device encryption using the @command{cryptsetup}
7177 command from the package with the same name. It relies on the
7178 @code{dm-crypt} Linux kernel module.
7181 @defvr {Scheme Variable} raid-device-mapping
7182 This defines a RAID device, which is assembled using the @code{mdadm}
7183 command from the package with the same name. It requires a Linux kernel
7184 module for the appropriate RAID level to be loaded, such as @code{raid456}
7185 for RAID-4, RAID-5 or RAID-6, or @code{raid10} for RAID-10.
7188 @cindex disk encryption
7190 The following example specifies a mapping from @file{/dev/sda3} to
7191 @file{/dev/mapper/home} using LUKS---the
7192 @url{http://code.google.com/p/cryptsetup,Linux Unified Key Setup}, a
7193 standard mechanism for disk encryption.
7194 The @file{/dev/mapper/home}
7195 device can then be used as the @code{device} of a @code{file-system}
7196 declaration (@pxref{File Systems}).
7200 (source "/dev/sda3")
7202 (type luks-device-mapping))
7205 Alternatively, to become independent of device numbering, one may obtain
7206 the LUKS UUID (@dfn{unique identifier}) of the source device by a
7210 cryptsetup luksUUID /dev/sda3
7213 and use it as follows:
7217 (source (uuid "cb67fc72-0d54-4c88-9d4b-b225f30b0f44"))
7219 (type luks-device-mapping))
7222 A RAID device formed of the partitions @file{/dev/sda1} and @file{/dev/sdb1}
7223 may be declared as follows:
7227 (source (list "/dev/sda1" "/dev/sdb1"))
7229 (type raid-device-mapping))
7232 The @file{/dev/md0} device can then be used as the @code{device} of a
7233 @code{file-system} declaration (@pxref{File Systems}).
7234 Note that the RAID level need not be given; it is chosen during the
7235 initial creation and formatting of the RAID device and is determined
7236 automatically later.
7240 @subsection User Accounts
7242 User accounts and groups are entirely managed through the
7243 @code{operating-system} declaration. They are specified with the
7244 @code{user-account} and @code{user-group} forms:
7250 (supplementary-groups '("wheel" ;allow use of sudo, etc.
7252 "video" ;video devices such as webcams
7253 "cdrom")) ;the good ol' CD-ROM
7254 (comment "Bob's sister")
7255 (home-directory "/home/alice"))
7258 When booting or upon completion of @command{guix system reconfigure},
7259 the system ensures that only the user accounts and groups specified in
7260 the @code{operating-system} declaration exist, and with the specified
7261 properties. Thus, account or group creations or modifications made by
7262 directly invoking commands such as @command{useradd} are lost upon
7263 reconfiguration or reboot. This ensures that the system remains exactly
7266 @deftp {Data Type} user-account
7267 Objects of this type represent user accounts. The following members may
7272 The name of the user account.
7275 This is the name (a string) or identifier (a number) of the user group
7276 this account belongs to.
7278 @item @code{supplementary-groups} (default: @code{'()})
7279 Optionally, this can be defined as a list of group names that this
7282 @item @code{uid} (default: @code{#f})
7283 This is the user ID for this account (a number), or @code{#f}. In the
7284 latter case, a number is automatically chosen by the system when the
7287 @item @code{comment} (default: @code{""})
7288 A comment about the account, such as the account owner's full name.
7290 @item @code{home-directory}
7291 This is the name of the home directory for the account.
7293 @item @code{create-home-directory?} (default: @code{#t})
7294 Indicates whether the home directory of this account should be created
7295 if it does not exist yet.
7297 @item @code{shell} (default: Bash)
7298 This is a G-expression denoting the file name of a program to be used as
7299 the shell (@pxref{G-Expressions}).
7301 @item @code{system?} (default: @code{#f})
7302 This Boolean value indicates whether the account is a ``system''
7303 account. System accounts are sometimes treated specially; for instance,
7304 graphical login managers do not list them.
7306 @anchor{user-account-password}
7307 @item @code{password} (default: @code{#f})
7308 You would normally leave this field to @code{#f}, initialize user
7309 passwords as @code{root} with the @command{passwd} command, and then let
7310 users change it with @command{passwd}. Passwords set with
7311 @command{passwd} are of course preserved across reboot and
7314 If you @emph{do} want to have a preset password for an account, then
7315 this field must contain the encrypted password, as a string.
7316 @xref{crypt,,, libc, The GNU C Library Reference Manual}, for more information
7317 on password encryption, and @ref{Encryption,,, guile, GNU Guile Reference
7318 Manual}, for information on Guile's @code{crypt} procedure.
7323 User group declarations are even simpler:
7326 (user-group (name "students"))
7329 @deftp {Data Type} user-group
7330 This type is for, well, user groups. There are just a few fields:
7334 The name of the group.
7336 @item @code{id} (default: @code{#f})
7337 The group identifier (a number). If @code{#f}, a new number is
7338 automatically allocated when the group is created.
7340 @item @code{system?} (default: @code{#f})
7341 This Boolean value indicates whether the group is a ``system'' group.
7342 System groups have low numerical IDs.
7344 @item @code{password} (default: @code{#f})
7345 What, user groups can have a password? Well, apparently yes. Unless
7346 @code{#f}, this field specifies the password of the group.
7351 For convenience, a variable lists all the basic user groups one may
7354 @defvr {Scheme Variable} %base-groups
7355 This is the list of basic user groups that users and/or packages expect
7356 to be present on the system. This includes groups such as ``root'',
7357 ``wheel'', and ``users'', as well as groups used to control access to
7358 specific devices such as ``audio'', ``disk'', and ``cdrom''.
7361 @defvr {Scheme Variable} %base-user-accounts
7362 This is the list of basic system accounts that programs may expect to
7363 find on a GNU/Linux system, such as the ``nobody'' account.
7365 Note that the ``root'' account is not included here. It is a
7366 special-case and is automatically added whether or not it is specified.
7373 A @dfn{locale} defines cultural conventions for a particular language
7374 and region of the world (@pxref{Locales,,, libc, The GNU C Library
7375 Reference Manual}). Each locale has a name that typically has the form
7376 @code{@var{language}_@var{territory}.@var{codeset}}---e.g.,
7377 @code{fr_LU.utf8} designates the locale for the French language, with
7378 cultural conventions from Luxembourg, and using the UTF-8 encoding.
7380 @cindex locale definition
7381 Usually, you will want to specify the default locale for the machine
7382 using the @code{locale} field of the @code{operating-system} declaration
7383 (@pxref{operating-system Reference, @code{locale}}).
7385 The selected locale is automatically added to the @dfn{locale
7386 definitions} known to the system if needed, with its codeset inferred
7387 from its name---e.g., @code{bo_CN.utf8} will be assumed to use the
7388 @code{UTF-8} codeset. Additional locale definitions can be specified in
7389 the @code{locale-definitions} slot of @code{operating-system}---this is
7390 useful, for instance, if the codeset could not be inferred from the
7391 locale name. The default set of locale definitions includes some widely
7392 used locales, but not all the available locales, in order to save space.
7394 For instance, to add the North Frisian locale for Germany, the value of
7398 (cons (locale-definition
7399 (name "fy_DE.utf8") (source "fy_DE"))
7400 %default-locale-definitions)
7403 Likewise, to save space, one might want @code{locale-definitions} to
7404 list only the locales that are actually used, as in:
7407 (list (locale-definition
7408 (name "ja_JP.eucjp") (source "ja_JP")
7409 (charset "EUC-JP")))
7413 The compiled locale definitions are available at
7414 @file{/run/current-system/locale/X.Y}, where @code{X.Y} is the libc
7415 version, which is the default location where the GNU@tie{}libc provided
7416 by Guix looks for locale data. This can be overridden using the
7417 @code{LOCPATH} environment variable (@pxref{locales-and-locpath,
7418 @code{LOCPATH} and locale packages}).
7420 The @code{locale-definition} form is provided by the @code{(gnu system
7421 locale)} module. Details are given below.
7423 @deftp {Data Type} locale-definition
7424 This is the data type of a locale definition.
7429 The name of the locale. @xref{Locale Names,,, libc, The GNU C Library
7430 Reference Manual}, for more information on locale names.
7433 The name of the source for that locale. This is typically the
7434 @code{@var{language}_@var{territory}} part of the locale name.
7436 @item @code{charset} (default: @code{"UTF-8"})
7437 The ``character set'' or ``code set'' for that locale,
7438 @uref{http://www.iana.org/assignments/character-sets, as defined by
7444 @defvr {Scheme Variable} %default-locale-definitions
7445 A list of commonly used UTF-8 locales, used as the default
7446 value of the @code{locale-definitions} field of @code{operating-system}
7450 @cindex normalized codeset in locale names
7451 These locale definitions use the @dfn{normalized codeset} for the part
7452 that follows the dot in the name (@pxref{Using gettextized software,
7453 normalized codeset,, libc, The GNU C Library Reference Manual}). So for
7454 instance it has @code{uk_UA.utf8} but @emph{not}, say,
7458 @subsubsection Locale Data Compatibility Considerations
7460 @cindex incompatibility, of locale data
7461 @code{operating-system} declarations provide a @code{locale-libcs} field
7462 to specify the GNU@tie{}libc packages that are used to compile locale
7463 declarations (@pxref{operating-system Reference}). ``Why would I
7464 care?'', you may ask. Well, it turns out that the binary format of
7465 locale data is occasionally incompatible from one libc version to
7468 @c See <https://sourceware.org/ml/libc-alpha/2015-09/msg00575.html>
7469 @c and <https://lists.gnu.org/archive/html/guix-devel/2015-08/msg00737.html>.
7470 For instance, a program linked against libc version 2.21 is unable to
7471 read locale data produced with libc 2.22; worse, that program
7472 @emph{aborts} instead of simply ignoring the incompatible locale
7473 data@footnote{Versions 2.23 and later of GNU@tie{}libc will simply skip
7474 the incompatible locale data, which is already an improvement.}.
7475 Similarly, a program linked against libc 2.22 can read most, but not
7476 all, of the locale data from libc 2.21 (specifically, @code{LC_COLLATE}
7477 data is incompatible); thus calls to @code{setlocale} may fail, but
7478 programs will not abort.
7480 The ``problem'' in GuixSD is that users have a lot of freedom: They can
7481 choose whether and when to upgrade software in their profiles, and might
7482 be using a libc version different from the one the system administrator
7483 used to build the system-wide locale data.
7485 Fortunately, unprivileged users can also install their own locale data
7486 and define @var{GUIX_LOCPATH} accordingly (@pxref{locales-and-locpath,
7487 @code{GUIX_LOCPATH} and locale packages}).
7489 Still, it is best if the system-wide locale data at
7490 @file{/run/current-system/locale} is built for all the libc versions
7491 actually in use on the system, so that all the programs can access
7492 it---this is especially crucial on a multi-user system. To do that, the
7493 administrator can specify several libc packages in the
7494 @code{locale-libcs} field of @code{operating-system}:
7497 (use-package-modules base)
7501 (locale-libcs (list glibc-2.21 (canonical-package glibc))))
7504 This example would lead to a system containing locale definitions for
7505 both libc 2.21 and the current version of libc in
7506 @file{/run/current-system/locale}.
7510 @subsection Services
7512 @cindex system services
7513 An important part of preparing an @code{operating-system} declaration is
7514 listing @dfn{system services} and their configuration (@pxref{Using the
7515 Configuration System}). System services are typically daemons launched
7516 when the system boots, or other actions needed at that time---e.g.,
7517 configuring network access.
7519 GuixSD has a broad definition of ``service'' (@pxref{Service
7520 Composition}), but many services are managed by the GNU@tie{}Shepherd
7521 (@pxref{Shepherd Services}). On a running system, the @command{herd}
7522 command allows you to list the available services, show their status,
7523 start and stop them, or do other specific operations (@pxref{Jump
7524 Start,,, shepherd, The GNU Shepherd Manual}). For example:
7530 The above command, run as @code{root}, lists the currently defined
7531 services. The @command{herd doc} command shows a synopsis of the given
7536 Run libc's name service cache daemon (nscd).
7539 The @command{start}, @command{stop}, and @command{restart} sub-commands
7540 have the effect you would expect. For instance, the commands below stop
7541 the nscd service and restart the Xorg display server:
7545 Service nscd has been stopped.
7546 # herd restart xorg-server
7547 Service xorg-server has been stopped.
7548 Service xorg-server has been started.
7551 The following sections document the available services, starting with
7552 the core services, that may be used in an @code{operating-system}
7556 * Base Services:: Essential system services.
7557 * Scheduled Job Execution:: The mcron service.
7558 * Networking Services:: Network setup, SSH daemon, etc.
7559 * X Window:: Graphical display.
7560 * Desktop Services:: D-Bus and desktop services.
7561 * Database Services:: SQL databases.
7562 * Mail Services:: IMAP, POP3, SMTP, and all that.
7563 * Web Services:: Web servers.
7564 * Various Services:: Other services.
7568 @subsubsection Base Services
7570 The @code{(gnu services base)} module provides definitions for the basic
7571 services that one expects from the system. The services exported by
7572 this module are listed below.
7574 @defvr {Scheme Variable} %base-services
7575 This variable contains a list of basic services (@pxref{Service Types
7576 and Services}, for more information on service objects) one would
7577 expect from the system: a login service (mingetty) on each tty, syslogd,
7578 the libc name service cache daemon (nscd), the udev device manager, and
7581 This is the default value of the @code{services} field of
7582 @code{operating-system} declarations. Usually, when customizing a
7583 system, you will want to append services to @var{%base-services}, like
7587 (cons* (avahi-service) (lsh-service) %base-services)
7591 @deffn {Scheme Procedure} host-name-service @var{name}
7592 Return a service that sets the host name to @var{name}.
7595 @deffn {Scheme Procedure} mingetty-service @var{config}
7596 Return a service to run mingetty according to @var{config}, a
7597 @code{<mingetty-configuration>} object, which specifies the tty to run, among
7601 @deftp {Data Type} mingetty-configuration
7602 This is the data type representing the configuration of Mingetty, which
7603 implements console log-in.
7608 The name of the console this Mingetty runs on---e.g., @code{"tty1"}.
7611 A file-like object containing the ``message of the day''.
7613 @item @code{auto-login} (default: @code{#f})
7614 When true, this field must be a string denoting the user name under
7615 which the system automatically logs in. When it is @code{#f}, a
7616 user name and password must be entered to log in.
7618 @item @code{login-program} (default: @code{#f})
7619 This must be either @code{#f}, in which case the default log-in program
7620 is used (@command{login} from the Shadow tool suite), or a gexp denoting
7621 the name of the log-in program.
7623 @item @code{login-pause?} (default: @code{#f})
7624 When set to @code{#t} in conjunction with @var{auto-login}, the user
7625 will have to press a key before the log-in shell is launched.
7627 @item @code{mingetty} (default: @var{mingetty})
7628 The Mingetty package to use.
7633 @cindex name service cache daemon
7635 @deffn {Scheme Procedure} nscd-service [@var{config}] [#:glibc glibc] @
7636 [#:name-services '()]
7637 Return a service that runs the libc name service cache daemon (nscd) with the
7638 given @var{config}---an @code{<nscd-configuration>} object. @xref{Name
7639 Service Switch}, for an example.
7642 @defvr {Scheme Variable} %nscd-default-configuration
7643 This is the default @code{<nscd-configuration>} value (see below) used
7644 by @code{nscd-service}. It uses the caches defined by
7645 @var{%nscd-default-caches}; see below.
7648 @deftp {Data Type} nscd-configuration
7649 This is the data type representing the name service cache daemon (nscd)
7654 @item @code{name-services} (default: @code{'()})
7655 List of packages denoting @dfn{name services} that must be visible to
7656 the nscd---e.g., @code{(list @var{nss-mdns})}.
7658 @item @code{glibc} (default: @var{glibc})
7659 Package object denoting the GNU C Library providing the @command{nscd}
7662 @item @code{log-file} (default: @code{"/var/log/nscd.log"})
7663 Name of the nscd log file. This is where debugging output goes when
7664 @code{debug-level} is strictly positive.
7666 @item @code{debug-level} (default: @code{0})
7667 Integer denoting the debugging levels. Higher numbers mean that more
7668 debugging output is logged.
7670 @item @code{caches} (default: @var{%nscd-default-caches})
7671 List of @code{<nscd-cache>} objects denoting things to be cached; see
7677 @deftp {Data Type} nscd-cache
7678 Data type representing a cache database of nscd and its parameters.
7682 @item @code{database}
7683 This is a symbol representing the name of the database to be cached.
7684 Valid values are @code{passwd}, @code{group}, @code{hosts}, and
7685 @code{services}, which designate the corresponding NSS database
7686 (@pxref{NSS Basics,,, libc, The GNU C Library Reference Manual}).
7688 @item @code{positive-time-to-live}
7689 @itemx @code{negative-time-to-live} (default: @code{20})
7690 A number representing the number of seconds during which a positive or
7691 negative lookup result remains in cache.
7693 @item @code{check-files?} (default: @code{#t})
7694 Whether to check for updates of the files corresponding to
7697 For instance, when @var{database} is @code{hosts}, setting this flag
7698 instructs nscd to check for updates in @file{/etc/hosts} and to take
7701 @item @code{persistent?} (default: @code{#t})
7702 Whether the cache should be stored persistently on disk.
7704 @item @code{shared?} (default: @code{#t})
7705 Whether the cache should be shared among users.
7707 @item @code{max-database-size} (default: 32@tie{}MiB)
7708 Maximum size in bytes of the database cache.
7710 @c XXX: 'suggested-size' and 'auto-propagate?' seem to be expert
7711 @c settings, so leave them out.
7716 @defvr {Scheme Variable} %nscd-default-caches
7717 List of @code{<nscd-cache>} objects used by default by
7718 @code{nscd-configuration} (see above).
7720 It enables persistent and aggressive caching of service and host name
7721 lookups. The latter provides better host name lookup performance,
7722 resilience in the face of unreliable name servers, and also better
7723 privacy---often the result of host name lookups is in local cache, so
7724 external name servers do not even need to be queried.
7727 @anchor{syslog-configuration-type}
7728 @deftp {Data Type} syslog-configuration
7729 This data type represents the configuration of the syslog daemon.
7732 @item @code{syslogd} (default: @code{#~(string-append #$inetutils "/libexec/syslogd")})
7733 The syslog daemon to use.
7735 @item @code{config-file} (default: @code{%default-syslog.conf})
7736 The syslog configuration file to use.
7741 @anchor{syslog-service}
7742 @deffn {Scheme Procedure} syslog-service @var{config}
7743 Return a service that runs a syslog daemon according to @var{config}.
7745 @xref{syslogd invocation,,, inetutils, GNU Inetutils}, for more
7746 information on the configuration file syntax.
7749 @anchor{guix-configuration-type}
7750 @deftp {Data Type} guix-configuration
7751 This data type represents the configuration of the Guix build daemon.
7752 @xref{Invoking guix-daemon}, for more information.
7755 @item @code{guix} (default: @var{guix})
7756 The Guix package to use.
7758 @item @code{build-group} (default: @code{"guixbuild"})
7759 Name of the group for build user accounts.
7761 @item @code{build-accounts} (default: @code{10})
7762 Number of build user accounts to create.
7764 @item @code{authorize-key?} (default: @code{#t})
7765 Whether to authorize the substitute keys listed in
7766 @code{authorized-keys}---by default that of @code{hydra.gnu.org}
7767 (@pxref{Substitutes}).
7769 @vindex %default-authorized-guix-keys
7770 @item @code{authorized-keys} (default: @var{%default-authorized-guix-keys})
7771 The list of authorized key files for archive imports, as a list of
7772 string-valued gexps (@pxref{Invoking guix archive}). By default, it
7773 contains that of @code{hydra.gnu.org} (@pxref{Substitutes}).
7775 @item @code{use-substitutes?} (default: @code{#t})
7776 Whether to use substitutes.
7778 @item @code{substitute-urls} (default: @var{%default-substitute-urls})
7779 The list of URLs where to look for substitutes by default.
7781 @item @code{extra-options} (default: @code{'()})
7782 List of extra command-line options for @command{guix-daemon}.
7784 @item @code{lsof} (default: @var{lsof})
7785 @itemx @code{lsh} (default: @var{lsh})
7786 The lsof and lsh packages to use.
7791 @deffn {Scheme Procedure} guix-service @var{config}
7792 Return a service that runs the Guix build daemon according to
7796 @deffn {Scheme Procedure} udev-service [#:udev udev]
7797 Run @var{udev}, which populates the @file{/dev} directory dynamically.
7800 @deffn {Scheme Procedure} urandom-seed-service @var{#f}
7801 Save some entropy in @var{%random-seed-file} to seed @file{/dev/urandom}
7805 @defvr {Scheme Variable} %random-seed-file
7806 This is the name of the file where some random bytes are saved by
7807 @var{urandom-seed-service} to seed @file{/dev/urandom} when rebooting.
7808 It defaults to @file{/var/lib/random-seed}.
7811 @deffn {Scheme Procedure} console-keymap-service @var{files} ...
7812 @cindex keyboard layout
7813 Return a service to load console keymaps from @var{files} using
7814 @command{loadkeys} command. Most likely, you want to load some default
7815 keymap, which can be done like this:
7818 (console-keymap-service "dvorak")
7821 Or, for example, for a Swedish keyboard, you may need to combine
7822 the following keymaps:
7824 (console-keymap-service "se-lat6" "se-fi-lat6")
7827 Also you can specify a full file name (or file names) of your keymap(s).
7828 See @code{man loadkeys} for details.
7832 @deffn {Scheme Procedure} gpm-service [#:gpm @var{gpm}] @
7834 Run @var{gpm}, the general-purpose mouse daemon, with the given
7835 command-line @var{options}. GPM allows users to use the mouse in the console,
7836 notably to select, copy, and paste text. The default value of @var{options}
7837 uses the @code{ps2} protocol, which works for both USB and PS/2 mice.
7839 This service is not part of @var{%base-services}.
7842 @anchor{guix-publish-service}
7843 @deffn {Scheme Procedure} guix-publish-service [#:guix @var{guix}] @
7844 [#:port 80] [#:host "localhost"]
7845 Return a service that runs @command{guix publish} listening on @var{host}
7846 and @var{port} (@pxref{Invoking guix publish}).
7848 This assumes that @file{/etc/guix} already contains a signing key pair as
7849 created by @command{guix archive --generate-key} (@pxref{Invoking guix
7850 archive}). If that is not the case, the service will fail to start.
7853 @anchor{rngd-service}
7854 @deffn {Scheme Procedure} rngd-service [#:rng-tools @var{rng-tools}] @
7855 [#:device "/dev/hwrng"]
7856 Return a service that runs the @command{rngd} program from @var{rng-tools}
7857 to add @var{device} to the kernel's entropy pool. The service will fail if
7858 @var{device} does not exist.
7861 @anchor{pam-limits-service}
7862 @cindex session limits
7865 @deffn {Scheme Procedure} pam-limits-service [#:limits @var{limits}]
7867 Return a service that installs a configuration file for the
7868 @uref{http://linux-pam.org/Linux-PAM-html/sag-pam_limits.html,
7869 @code{pam_limits} module}. The procedure optionally takes a list of
7870 @code{pam-limits-entry} values, which can be used to specify
7871 @code{ulimit} limits and nice priority limits to user sessions.
7873 The following limits definition sets two hard and soft limits for all
7874 login sessions of users in the @code{realtime} group:
7879 (pam-limits-entry "@@realtime" 'both 'rtprio 99)
7880 (pam-limits-entry "@@realtime" 'both 'memlock 'unlimited)))
7883 The first entry increases the maximum realtime priority for
7884 non-privileged processes; the second entry lifts any restriction of the
7885 maximum address space that can be locked in memory. These settings are
7886 commonly used for real-time audio systems.
7889 @node Scheduled Job Execution
7890 @subsubsection Scheduled Job Execution
7893 @cindex scheduling jobs
7894 The @code{(gnu services mcron)} module provides an interface to
7895 GNU@tie{}mcron, a daemon to run jobs at scheduled times (@pxref{Top,,,
7896 mcron, GNU@tie{}mcron}). GNU@tie{}mcron is similar to the traditional
7897 Unix @command{cron} daemon; the main difference is that it is
7898 implemented in Guile Scheme, which provides a lot of flexibility when
7899 specifying the scheduling of jobs and their actions.
7901 The example below defines an operating system that runs the
7902 @command{updatedb} (@pxref{Invoking updatedb,,, find, Finding Files})
7903 and the @command{guix gc} commands (@pxref{Invoking guix gc}) daily, as
7904 well as the @command{mkid} command on behalf of an unprivileged user
7905 (@pxref{mkid invocation,,, idutils, ID Database Utilities}). It uses
7906 gexps to introduce job definitions that are passed to mcron
7907 (@pxref{G-Expressions}).
7910 (use-modules (guix) (gnu) (gnu services mcron))
7911 (use-package-modules base idutils)
7913 (define updatedb-job
7914 ;; Run 'updatedb' at 3AM every day. Here we write the
7915 ;; job's action as a Scheme procedure.
7916 #~(job '(next-hour '(3))
7918 (execl (string-append #$findutils "/bin/updatedb")
7920 "--prunepaths=/tmp /var/tmp /gnu/store"))))
7922 (define garbage-collector-job
7923 ;; Collect garbage 5 minutes after midnight every day.
7924 ;; The job's action is a shell command.
7925 #~(job "5 0 * * *" ;Vixie cron syntax
7929 ;; Update the index database as user "charlie" at 12:15PM
7930 ;; and 19:15PM. This runs from the user's home directory.
7931 #~(job '(next-minute-from (next-hour '(12 19)) '(15))
7932 (string-append #$idutils "/bin/mkid src")
7937 (services (cons (mcron-service (list garbage-collector-job
7943 @xref{Guile Syntax, mcron job specifications,, mcron, GNU@tie{}mcron},
7944 for more information on mcron job specifications. Below is the
7945 reference of the mcron service.
7947 @deffn {Scheme Procedure} mcron-service @var{jobs} [#:mcron @var{mcron2}]
7948 Return an mcron service running @var{mcron} that schedules @var{jobs}, a
7949 list of gexps denoting mcron job specifications.
7951 This is a shorthand for:
7953 (service mcron-service-type
7954 (mcron-configuration (mcron mcron) (jobs jobs)))
7958 @defvr {Scheme Variable} mcron-service-type
7959 This is the type of the @code{mcron} service, whose value is an
7960 @code{mcron-configuration} object.
7962 This service type can be the target of a service extension that provides
7963 it additional job specifications (@pxref{Service Composition}). In
7964 other words, it is possible to define services that provide additional
7968 @deftp {Data Type} mcron-configuration
7969 Data type representing the configuration of mcron.
7972 @item @code{mcron} (default: @var{mcron2})
7973 The mcron package to use.
7976 This is a list of gexps (@pxref{G-Expressions}), where each gexp
7977 corresponds to an mcron job specification (@pxref{Syntax, mcron job
7978 specifications,, mcron, GNU@tie{}mcron}).
7983 @node Networking Services
7984 @subsubsection Networking Services
7986 The @code{(gnu services networking)} module provides services to configure
7987 the network interface.
7989 @cindex DHCP, networking service
7990 @deffn {Scheme Procedure} dhcp-client-service [#:dhcp @var{isc-dhcp}]
7991 Return a service that runs @var{dhcp}, a Dynamic Host Configuration
7992 Protocol (DHCP) client, on all the non-loopback network interfaces.
7995 @deffn {Scheme Procedure} static-networking-service @var{interface} @var{ip} @
7996 [#:gateway #f] [#:name-servers @code{'()}]
7997 Return a service that starts @var{interface} with address @var{ip}. If
7998 @var{gateway} is true, it must be a string specifying the default network
8003 @cindex network management
8004 @deffn {Scheme Procedure} wicd-service [#:wicd @var{wicd}]
8005 Return a service that runs @url{https://launchpad.net/wicd,Wicd}, a network
8006 management daemon that aims to simplify wired and wireless networking.
8008 This service adds the @var{wicd} package to the global profile, providing
8009 several commands to interact with the daemon and configure networking:
8010 @command{wicd-client}, a graphical user interface, and the @command{wicd-cli}
8011 and @command{wicd-curses} user interfaces.
8014 @cindex NetworkManager
8015 @deffn {Scheme Procedure} network-manager-service @
8016 [#:network-manager @var{network-manager}]
8017 Return a service that runs NetworkManager, a network connection manager
8018 attempting to keep network connectivity active when available.
8022 @deffn {Scheme Procedure} connman-service @
8023 [#:connman @var{connman}]
8024 Return a service that runs @url{https://01.org/connman,Connman}, a network
8027 This service adds the @var{connman} package to the global profile, providing
8028 several the @command{connmanctl} command to interact with the daemon and
8029 configure networking."
8032 @deffn {Scheme Procedure} ntp-service [#:ntp @var{ntp}] @
8033 [#:servers @var{%ntp-servers}]
8034 Return a service that runs the daemon from @var{ntp}, the
8035 @uref{http://www.ntp.org, Network Time Protocol package}. The daemon will
8036 keep the system clock synchronized with that of @var{servers}.
8039 @defvr {Scheme Variable} %ntp-servers
8040 List of host names used as the default NTP servers.
8043 @deffn {Scheme Procedure} tor-service [@var{config-file}] [#:tor @var{tor}]
8044 Return a service to run the @uref{https://torproject.org, Tor} anonymous
8047 The daemon runs as the @code{tor} unprivileged user. It is passed
8048 @var{config-file}, a file-like object, with an additional @code{User tor} line
8049 and lines for hidden services added via @code{tor-hidden-service}. Run
8050 @command{man tor} for information about the configuration file.
8053 @cindex hidden service
8054 @deffn {Scheme Procedure} tor-hidden-service @var{name} @var{mapping}
8055 Define a new Tor @dfn{hidden service} called @var{name} and implementing
8056 @var{mapping}. @var{mapping} is a list of port/host tuples, such as:
8059 '((22 "127.0.0.1:22")
8060 (80 "127.0.0.1:8080"))
8063 In this example, port 22 of the hidden service is mapped to local port 22, and
8064 port 80 is mapped to local port 8080.
8066 This creates a @file{/var/lib/tor/hidden-services/@var{name}} directory, where
8067 the @file{hostname} file contains the @code{.onion} host name for the hidden
8070 See @uref{https://www.torproject.org/docs/tor-hidden-service.html.en, the Tor
8071 project's documentation} for more information.
8074 @deffn {Scheme Procedure} bitlbee-service [#:bitlbee bitlbee] @
8075 [#:interface "127.0.0.1"] [#:port 6667] @
8076 [#:extra-settings ""]
8077 Return a service that runs @url{http://bitlbee.org,BitlBee}, a daemon that
8078 acts as a gateway between IRC and chat networks.
8080 The daemon will listen to the interface corresponding to the IP address
8081 specified in @var{interface}, on @var{port}. @code{127.0.0.1} means that only
8082 local clients can connect, whereas @code{0.0.0.0} means that connections can
8083 come from any networking interface.
8085 In addition, @var{extra-settings} specifies a string to append to the
8089 Furthermore, @code{(gnu services ssh)} provides the following services.
8091 @deffn {Scheme Procedure} lsh-service [#:host-key "/etc/lsh/host-key"] @
8092 [#:daemonic? #t] [#:interfaces '()] [#:port-number 22] @
8093 [#:allow-empty-passwords? #f] [#:root-login? #f] @
8094 [#:syslog-output? #t] [#:x11-forwarding? #t] @
8095 [#:tcp/ip-forwarding? #t] [#:password-authentication? #t] @
8096 [#:public-key-authentication? #t] [#:initialize? #t]
8097 Run the @command{lshd} program from @var{lsh} to listen on port @var{port-number}.
8098 @var{host-key} must designate a file containing the host key, and readable
8101 When @var{daemonic?} is true, @command{lshd} will detach from the
8102 controlling terminal and log its output to syslogd, unless one sets
8103 @var{syslog-output?} to false. Obviously, it also makes lsh-service
8104 depend on existence of syslogd service. When @var{pid-file?} is true,
8105 @command{lshd} writes its PID to the file called @var{pid-file}.
8107 When @var{initialize?} is true, automatically create the seed and host key
8108 upon service activation if they do not exist yet. This may take long and
8109 require interaction.
8111 When @var{initialize?} is false, it is up to the user to initialize the
8112 randomness generator (@pxref{lsh-make-seed,,, lsh, LSH Manual}), and to create
8113 a key pair with the private key stored in file @var{host-key} (@pxref{lshd
8114 basics,,, lsh, LSH Manual}).
8116 When @var{interfaces} is empty, lshd listens for connections on all the
8117 network interfaces; otherwise, @var{interfaces} must be a list of host names
8120 @var{allow-empty-passwords?} specifies whether to accept log-ins with empty
8121 passwords, and @var{root-login?} specifies whether to accept log-ins as
8124 The other options should be self-descriptive.
8127 @deffn {Scheme Procedure} dropbear-service [@var{config}]
8128 Run the @uref{https://matt.ucc.asn.au/dropbear/dropbear.html,Dropbear SSH
8129 daemon} with the given @var{config}, a @code{<dropbear-configuration>}
8132 For example, to specify a Dropbear service listening on port 1234, add
8133 this call to the operating system's @code{services} field:
8136 (dropbear-service (dropbear-configuration
8137 (port-number 1234)))
8141 @deftp {Data Type} dropbear-configuration
8142 This data type represents the configuration of a Dropbear SSH daemon.
8145 @item @code{dropbear} (default: @var{dropbear})
8146 The Dropbear package to use.
8148 @item @code{port-number} (default: 22)
8149 The TCP port where the daemon waits for incoming connections.
8151 @item @code{syslog-output?} (default: @code{#t})
8152 Whether to enable syslog output.
8154 @item @code{pid-file} (default: @code{"/var/run/dropbear.pid"})
8155 File name of the daemon's PID file.
8157 @item @code{root-login?} (default: @code{#f})
8158 Whether to allow @code{root} logins.
8160 @item @code{allow-empty-passwords?} (default: @code{#f})
8161 Whether to allow empty passwords.
8163 @item @code{password-authentication?} (default: @code{#t})
8164 Whether to enable password-based authentication.
8168 @defvr {Scheme Variable} %facebook-host-aliases
8169 This variable contains a string for use in @file{/etc/hosts}
8170 (@pxref{Host Names,,, libc, The GNU C Library Reference Manual}). Each
8171 line contains a entry that maps a known server name of the Facebook
8172 on-line service---e.g., @code{www.facebook.com}---to the local
8173 host---@code{127.0.0.1} or its IPv6 equivalent, @code{::1}.
8175 This variable is typically used in the @code{hosts-file} field of an
8176 @code{operating-system} declaration (@pxref{operating-system Reference,
8177 @file{/etc/hosts}}):
8180 (use-modules (gnu) (guix))
8183 (host-name "mymachine")
8186 ;; Create a /etc/hosts file with aliases for "localhost"
8187 ;; and "mymachine", as well as for Facebook servers.
8189 (string-append (local-host-aliases host-name)
8190 %facebook-host-aliases))))
8193 This mechanism can prevent programs running locally, such as Web
8194 browsers, from accessing Facebook.
8197 The @code{(gnu services avahi)} provides the following definition.
8199 @deffn {Scheme Procedure} avahi-service [#:avahi @var{avahi}] @
8200 [#:host-name #f] [#:publish? #t] [#:ipv4? #t] @
8201 [#:ipv6? #t] [#:wide-area? #f] @
8202 [#:domains-to-browse '()] [#:debug? #f]
8203 Return a service that runs @command{avahi-daemon}, a system-wide
8204 mDNS/DNS-SD responder that allows for service discovery and
8205 "zero-configuration" host name lookups (see @uref{http://avahi.org/}), and
8206 extends the name service cache daemon (nscd) so that it can resolve
8207 @code{.local} host names using
8208 @uref{http://0pointer.de/lennart/projects/nss-mdns/, nss-mdns}. Additionally,
8209 add the @var{avahi} package to the system profile so that commands such as
8210 @command{avahi-browse} are directly usable.
8212 If @var{host-name} is different from @code{#f}, use that as the host name to
8213 publish for this machine; otherwise, use the machine's actual host name.
8215 When @var{publish?} is true, publishing of host names and services is allowed;
8216 in particular, avahi-daemon will publish the machine's host name and IP
8217 address via mDNS on the local network.
8219 When @var{wide-area?} is true, DNS-SD over unicast DNS is enabled.
8221 Boolean values @var{ipv4?} and @var{ipv6?} determine whether to use IPv4/IPv6
8227 @subsubsection X Window
8229 Support for the X Window graphical display system---specifically
8230 Xorg---is provided by the @code{(gnu services xorg)} module. Note that
8231 there is no @code{xorg-service} procedure. Instead, the X server is
8232 started by the @dfn{login manager}, currently SLiM.
8234 @deftp {Data Type} sddm-configuration
8235 This is the data type representing the sddm service configuration.
8238 @item @code{display-server} (default: "x11")
8239 Select display server to use for the greeter. Valid values are "x11"
8242 @item @code{numlock} (default: "on")
8243 Valid values are "on", "off" or "none".
8245 @item @code{halt-command} (default @code{#~(string-apppend #$shepherd "/sbin/halt")})
8246 Command to run when halting.
8248 @item @code{reboot-command} (default @code{#~(string-append #$shepherd "/sbin/reboot")})
8249 Command to run when rebooting.
8251 @item @code{theme} (default "maldives")
8252 Theme to use. Default themes provided by SDDM are "elarun" or "maldives".
8254 @item @code{themes-directory} (default "/run/current-system/profile/share/sddm/themes")
8255 Directory to look for themes.
8257 @item @code{faces-directory} (default "/run/current-system/profile/share/sddm/faces")
8258 Directory to look for faces.
8260 @item @code{default-path} (default "/run/current-system/profile/bin")
8261 Default PATH to use.
8263 @item @code{minimum-uid} (default 1000)
8264 Minimum UID to display in SDDM.
8266 @item @code{maximum-uid} (default 2000)
8267 Maximum UID to display in SDDM
8269 @item @code{remember-last-user?} (default #t)
8272 @item @code{remember-last-session?} (default #t)
8273 Remember last session.
8275 @item @code{hide-users} (default "")
8276 Usernames to hide from SDDM greeter.
8278 @item @code{hide-shells} (default @code{#~(string-append #$shadow "/sbin/nologin")})
8279 Users with shells listed will be hidden from the SDDM greeter.
8281 @item @code{session-command} (default @code{#~(string-append #$sddm "/share/sddm/scripts/wayland-session")})
8282 Script to run before starting a wayland session.
8284 @item @code{sessions-directory} (default "/run/current-system/profile/share/wayland-sessions")
8285 Directory to look for desktop files starting wayland sessions.
8287 @item @code{xorg-server-path} (default @code{xorg-start-command})
8288 Path to xorg-server.
8290 @item @code{xauth-path} (default @code{#~(string-append #$xauth "/bin/xauth")})
8293 @item @code{xephyr-path} (default @code{#~(string-append #$xorg-server "/bin/Xephyr")})
8296 @item @code{xdisplay-start} (default @code{#~(string-append #$sddm "/share/sddm/scripts/Xsetup")})
8297 Script to run after starting xorg-server.
8299 @item @code{xdisplay-stop} (default @code{#~(string-append #$sddm "/share/sddm/scripts/Xstop")})
8300 Script to run before stopping xorg-server.
8302 @item @code{xsession-command} (default: @code{xinitr })
8303 Script to run before starting a X session.
8305 @item @code{xsessions-directory} (default: "/run/current-system/profile/share/xsessions")
8306 Directory to look for desktop files starting X sessions.
8308 @item @code{minimum-vt} (default: 7)
8311 @item @code{xserver-arguments} (default "-nolisten tcp")
8312 Arguments to pass to xorg-server.
8314 @item @code{auto-login-user} (default "")
8315 User to use for auto-login.
8317 @item @code{auto-login-session} (default "")
8318 Desktop file to use for auto-login.
8320 @item @code{relogin?} (default #f)
8321 Relogin after logout.
8326 @deffn {Scheme Procedure} sddm-service config
8327 Return a service that spawns the SDDM graphical login manager for config of
8328 type @code{<sddm-configuration>}.
8331 (sddm-service (sddm-configuration
8332 (auto-login-user "Alice")
8333 (auto-login-session "xfce.desktop")))
8337 @deffn {Scheme Procedure} slim-service [#:allow-empty-passwords? #f] @
8338 [#:auto-login? #f] [#:default-user ""] [#:startx] @
8339 [#:theme @var{%default-slim-theme}] @
8340 [#:theme-name @var{%default-slim-theme-name}]
8341 Return a service that spawns the SLiM graphical login manager, which in
8342 turn starts the X display server with @var{startx}, a command as returned by
8343 @code{xorg-start-command}.
8347 SLiM automatically looks for session types described by the @file{.desktop}
8348 files in @file{/run/current-system/profile/share/xsessions} and allows users
8349 to choose a session from the log-in screen using @kbd{F1}. Packages such as
8350 @var{xfce}, @var{sawfish}, and @var{ratpoison} provide @file{.desktop} files;
8351 adding them to the system-wide set of packages automatically makes them
8352 available at the log-in screen.
8354 In addition, @file{~/.xsession} files are honored. When available,
8355 @file{~/.xsession} must be an executable that starts a window manager
8356 and/or other X clients.
8358 When @var{allow-empty-passwords?} is true, allow logins with an empty
8359 password. When @var{auto-login?} is true, log in automatically as
8362 If @var{theme} is @code{#f}, use the default log-in theme; otherwise
8363 @var{theme} must be a gexp denoting the name of a directory containing the
8364 theme to use. In that case, @var{theme-name} specifies the name of the
8368 @defvr {Scheme Variable} %default-theme
8369 @defvrx {Scheme Variable} %default-theme-name
8370 The G-Expression denoting the default SLiM theme and its name.
8373 @deffn {Scheme Procedure} xorg-start-command [#:guile] @
8374 [#:configuration-file #f] [#:xorg-server @var{xorg-server}]
8375 Return a derivation that builds a @var{guile} script to start the X server
8376 from @var{xorg-server}. @var{configuration-file} is the server configuration
8377 file or a derivation that builds it; when omitted, the result of
8378 @code{xorg-configuration-file} is used.
8380 Usually the X server is started by a login manager.
8383 @deffn {Scheme Procedure} xorg-configuration-file @
8384 [#:drivers '()] [#:resolutions '()] [#:extra-config '()]
8385 Return a configuration file for the Xorg server containing search paths for
8386 all the common drivers.
8388 @var{drivers} must be either the empty list, in which case Xorg chooses a
8389 graphics driver automatically, or a list of driver names that will be tried in
8390 this order---e.g., @code{(\"modesetting\" \"vesa\")}.
8392 Likewise, when @var{resolutions} is the empty list, Xorg chooses an
8393 appropriate screen resolution; otherwise, it must be a list of
8394 resolutions---e.g., @code{((1024 768) (640 480))}.
8396 Last, @var{extra-config} is a list of strings or objects appended to the
8397 @code{text-file*} argument list. It is used to pass extra text to be added
8398 verbatim to the configuration file.
8401 @deffn {Scheme Procedure} screen-locker-service @var{package} [@var{name}]
8402 Add @var{package}, a package for a screen-locker or screen-saver whose
8403 command is @var{program}, to the set of setuid programs and add a PAM entry
8404 for it. For example:
8407 (screen-locker-service xlockmore "xlock")
8410 makes the good ol' XlockMore usable.
8414 @node Desktop Services
8415 @subsubsection Desktop Services
8417 The @code{(gnu services desktop)} module provides services that are
8418 usually useful in the context of a ``desktop'' setup---that is, on a
8419 machine running a graphical display server, possibly with graphical user
8420 interfaces, etc. It also defines services that provide specific desktop
8421 environments like GNOME and XFCE.
8423 To simplify things, the module defines a variable containing the set of
8424 services that users typically expect on a machine with a graphical
8425 environment and networking:
8427 @defvr {Scheme Variable} %desktop-services
8428 This is a list of services that builds upon @var{%base-services} and
8429 adds or adjusts services for a typical ``desktop'' setup.
8431 In particular, it adds a graphical login manager (@pxref{X Window,
8432 @code{slim-service}}), screen lockers,
8433 a network management tool (@pxref{Networking
8434 Services, @code{wicd-service}}), energy and color management services,
8435 the @code{elogind} login and seat manager, the Polkit privilege service,
8436 the GeoClue location service, an NTP client (@pxref{Networking
8437 Services}), the Avahi daemon, and has the name service switch service
8438 configured to be able to use @code{nss-mdns} (@pxref{Name Service
8442 The @var{%desktop-services} variable can be used as the @code{services}
8443 field of an @code{operating-system} declaration (@pxref{operating-system
8444 Reference, @code{services}}).
8446 Additionally, the @code{gnome-desktop-service} and
8447 @code{xfce-desktop-service} procedures can add GNOME and/or XFCE to a
8448 system. To ``add GNOME'' means that system-level services like the
8449 backlight adjustment helpers and the power management utilities are
8450 added to the system, extending @code{polkit} and @code{dbus}
8451 appropriately, allowing GNOME to operate with elevated privileges on a
8452 limited number of special-purpose system interfaces. Additionally,
8453 adding a service made by @code{gnome-desktop-service} adds the GNOME
8454 metapackage to the system profile. Likewise, adding the XFCE service
8455 not only adds the @code{xfce} metapackage to the system profile, but it
8456 also gives the Thunar file manager the ability to open a ``root-mode''
8457 file management window, if the user authenticates using the
8458 administrator's password via the standard polkit graphical interface.
8460 @deffn {Scheme Procedure} gnome-desktop-service
8461 Return a service that adds the @code{gnome} package to the system
8462 profile, and extends polkit with the actions from
8463 @code{gnome-settings-daemon}.
8466 @deffn {Scheme Procedure} xfce-desktop-service
8467 Return a service that adds the @code{xfce} package to the system profile,
8468 and extends polkit with the ability for @code{thunar} to manipulate the
8469 file system as root from within a user session, after the user has
8470 authenticated with the administrator's password.
8473 Because the GNOME and XFCE desktop services pull in so many packages,
8474 the default @code{%desktop-services} variable doesn't include either of
8475 them by default. To add GNOME or XFCE, just @code{cons} them onto
8476 @code{%desktop-services} in the @code{services} field of your
8477 @code{operating-system}:
8481 (use-service-modules desktop)
8484 ;; cons* adds items to the list given as its last argument.
8485 (services (cons* (gnome-desktop-service)
8486 (xfce-desktop-service)
8491 These desktop environments will then be available as options in the
8492 graphical login window.
8494 The actual service definitions included in @code{%desktop-services} and
8495 provided by @code{(gnu services dbus)} and @code{(gnu services desktop)}
8496 are described below.
8498 @deffn {Scheme Procedure} dbus-service [#:dbus @var{dbus}] [#:services '()]
8499 Return a service that runs the ``system bus'', using @var{dbus}, with
8500 support for @var{services}.
8502 @uref{http://dbus.freedesktop.org/, D-Bus} is an inter-process communication
8503 facility. Its system bus is used to allow system services to communicate
8504 and to be notified of system-wide events.
8506 @var{services} must be a list of packages that provide an
8507 @file{etc/dbus-1/system.d} directory containing additional D-Bus configuration
8508 and policy files. For example, to allow avahi-daemon to use the system bus,
8509 @var{services} must be equal to @code{(list avahi)}.
8512 @deffn {Scheme Procedure} elogind-service [#:config @var{config}]
8513 Return a service that runs the @code{elogind} login and
8514 seat management daemon. @uref{https://github.com/andywingo/elogind,
8515 Elogind} exposes a D-Bus interface that can be used to know which users
8516 are logged in, know what kind of sessions they have open, suspend the
8517 system, inhibit system suspend, reboot the system, and other tasks.
8519 Elogind handles most system-level power events for a computer, for
8520 example suspending the system when a lid is closed, or shutting it down
8521 when the power button is pressed.
8523 The @var{config} keyword argument specifies the configuration for
8524 elogind, and should be the result of an @code{(elogind-configuration
8525 (@var{parameter} @var{value})...)} invocation. Available parameters and
8526 their default values are:
8529 @item kill-user-processes?
8531 @item kill-only-users
8533 @item kill-exclude-users
8535 @item inhibit-delay-max-seconds
8537 @item handle-power-key
8539 @item handle-suspend-key
8541 @item handle-hibernate-key
8543 @item handle-lid-switch
8545 @item handle-lid-switch-docked
8547 @item power-key-ignore-inhibited?
8549 @item suspend-key-ignore-inhibited?
8551 @item hibernate-key-ignore-inhibited?
8553 @item lid-switch-ignore-inhibited?
8555 @item holdoff-timeout-seconds
8559 @item idle-action-seconds
8561 @item runtime-directory-size-percent
8563 @item runtime-directory-size
8568 @code{("mem" "standby" "freeze")}
8571 @item hibernate-state
8573 @item hibernate-mode
8574 @code{("platform" "shutdown")}
8575 @item hybrid-sleep-state
8577 @item hybrid-sleep-mode
8578 @code{("suspend" "platform" "shutdown")}
8582 @deffn {Scheme Procedure} polkit-service @
8583 [#:polkit @var{polkit}]
8584 Return a service that runs the
8585 @uref{http://www.freedesktop.org/wiki/Software/polkit/, Polkit privilege
8586 management service}, which allows system administrators to grant access to
8587 privileged operations in a structured way. By querying the Polkit service, a
8588 privileged system component can know when it should grant additional
8589 capabilities to ordinary users. For example, an ordinary user can be granted
8590 the capability to suspend the system if the user is logged in locally.
8593 @deffn {Scheme Procedure} upower-service [#:upower @var{upower}] @
8594 [#:watts-up-pro? #f] @
8595 [#:poll-batteries? #t] @
8596 [#:ignore-lid? #f] @
8597 [#:use-percentage-for-policy? #f] @
8598 [#:percentage-low 10] @
8599 [#:percentage-critical 3] @
8600 [#:percentage-action 2] @
8602 [#:time-critical 300] @
8603 [#:time-action 120] @
8604 [#:critical-power-action 'hybrid-sleep]
8605 Return a service that runs @uref{http://upower.freedesktop.org/,
8606 @command{upowerd}}, a system-wide monitor for power consumption and battery
8607 levels, with the given configuration settings. It implements the
8608 @code{org.freedesktop.UPower} D-Bus interface, and is notably used by
8612 @deffn {Scheme Procedure} udisks-service [#:udisks @var{udisks}]
8613 Return a service for @uref{http://udisks.freedesktop.org/docs/latest/,
8614 UDisks}, a @dfn{disk management} daemon that provides user interfaces with
8615 notifications and ways to mount/unmount disks. Programs that talk to UDisks
8616 include the @command{udisksctl} command, part of UDisks, and GNOME Disks.
8619 @deffn {Scheme Procedure} colord-service [#:colord @var{colord}]
8620 Return a service that runs @command{colord}, a system service with a D-Bus
8621 interface to manage the color profiles of input and output devices such as
8622 screens and scanners. It is notably used by the GNOME Color Manager graphical
8623 tool. See @uref{http://www.freedesktop.org/software/colord/, the colord web
8624 site} for more information.
8627 @deffn {Scheme Procedure} geoclue-application name [#:allowed? #t] [#:system? #f] [#:users '()]
8628 Return a configuration allowing an application to access GeoClue
8629 location data. @var{name} is the Desktop ID of the application, without
8630 the @code{.desktop} part. If @var{allowed?} is true, the application
8631 will have access to location information by default. The boolean
8632 @var{system?} value indicates whether an application is a system component
8633 or not. Finally @var{users} is a list of UIDs of all users for which
8634 this application is allowed location info access. An empty users list
8635 means that all users are allowed.
8638 @defvr {Scheme Variable} %standard-geoclue-applications
8639 The standard list of well-known GeoClue application configurations,
8640 granting authority to the GNOME date-and-time utility to ask for the
8641 current location in order to set the time zone, and allowing the
8642 IceCat and Epiphany web browsers to request location information.
8643 IceCat and Epiphany both query the user before allowing a web page to
8644 know the user's location.
8647 @deffn {Scheme Procedure} geoclue-service [#:colord @var{colord}] @
8649 [#:wifi-geolocation-url "https://location.services.mozilla.com/v1/geolocate?key=geoclue"] @
8651 [#:wifi-submission-url "https://location.services.mozilla.com/v1/submit?key=geoclue"] @
8652 [#:submission-nick "geoclue"] @
8653 [#:applications %standard-geoclue-applications]
8654 Return a service that runs the GeoClue location service. This service
8655 provides a D-Bus interface to allow applications to request access to a
8656 user's physical location, and optionally to add information to online
8657 location databases. See
8658 @uref{https://wiki.freedesktop.org/www/Software/GeoClue/, the GeoClue
8659 web site} for more information.
8662 @deffn {Scheme Procedure} bluetooth-service [#:bluez @var{bluez}]
8663 Return a service that runs the @command{bluetoothd} daemon, which manages
8664 all the Bluetooth devices and provides a number of D-Bus interfaces.
8666 Users need to be in the @code{lp} group to access the D-Bus service.
8669 @node Database Services
8670 @subsubsection Database Services
8672 The @code{(gnu services databases)} module provides the following services.
8674 @deffn {Scheme Procedure} postgresql-service [#:postgresql postgresql] @
8675 [#:config-file] [#:data-directory ``/var/lib/postgresql/data'']
8676 Return a service that runs @var{postgresql}, the PostgreSQL database
8679 The PostgreSQL daemon loads its runtime configuration from
8680 @var{config-file} and stores the database cluster in
8681 @var{data-directory}.
8684 @deffn {Scheme Procedure} mysql-service [#:config (mysql-configuration)]
8685 Return a service that runs @command{mysqld}, the MySQL or MariaDB
8688 The optional @var{config} argument specifies the configuration for
8689 @command{mysqld}, which should be a @code{<mysql-configuraiton>} object.
8692 @deftp {Data Type} mysql-configuration
8693 Data type representing the configuration of @var{mysql-service}.
8696 @item @code{mysql} (default: @var{mariadb})
8697 Package object of the MySQL database server, can be either @var{mariadb}
8700 For MySQL, a temporary root password will be displayed at activation time.
8701 For MariaDB, the root password is empty.
8706 @subsubsection Mail Services
8708 The @code{(gnu services mail)} module provides Guix service definitions
8709 for mail services. Currently the only implemented service is Dovecot,
8710 an IMAP, POP3, and LMTP server.
8712 Guix does not yet have a mail transfer agent (MTA), although for some
8713 lightweight purposes the @code{esmtp} relay-only MTA may suffice. Help
8714 is needed to properly integrate a full MTA, such as Postfix. Patches
8717 To add an IMAP/POP3 server to a GuixSD system, add a
8718 @code{dovecot-service} to the operating system definition:
8720 @deffn {Scheme Procedure} dovecot-service [#:config (dovecot-configuration)]
8721 Return a service that runs the Dovecot IMAP/POP3/LMTP mail server.
8724 By default, Dovecot does not need much configuration; the default
8725 configuration object created by @code{(dovecot-configuration)} will
8726 suffice if your mail is delivered to @code{~/Maildir}. A self-signed
8727 certificate will be generated for TLS-protected connections, though
8728 Dovecot will also listen on cleartext ports by default. There are a
8729 number of options, though, which mail administrators might need to change,
8730 and as is the case with other services, Guix allows the system
8731 administrator to specify these parameters via a uniform Scheme interface.
8733 For example, to specify that mail is located at @code{maildir~/.mail},
8734 one would instantiate the Dovecot service like this:
8737 (dovecot-service #:config
8738 (dovecot-configuration
8739 (mail-location "maildir:~/.mail")))
8742 The available configuration parameters follow. Each parameter
8743 definition is preceded by its type; for example, @samp{string-list foo}
8744 indicates that the @code{foo} parameter should be specified as a list of
8745 strings. There is also a way to specify the configuration as a string,
8746 if you have an old @code{dovecot.conf} file that you want to port over
8747 from some other system; see the end for more details.
8749 @c The following documentation was initially generated by
8750 @c (generate-documentation) in (gnu services mail). Manually maintained
8751 @c documentation is better, so we shouldn't hesitate to edit below as
8752 @c needed. However if the change you want to make to this documentation
8753 @c can be done in an automated way, it's probably easier to change
8754 @c (generate-documentation) than to make it below and have to deal with
8755 @c the churn as dovecot updates.
8757 Available @code{dovecot-configuration} fields are:
8759 @deftypevr {@code{dovecot-configuration} parameter} package dovecot
8760 The dovecot package.
8763 @deftypevr {@code{dovecot-configuration} parameter} comma-separated-string-list listen
8764 A list of IPs or hosts where to listen for connections. @samp{*}
8765 listens on all IPv4 interfaces, @samp{::} listens on all IPv6
8766 interfaces. If you want to specify non-default ports or anything more
8767 complex, customize the address and port fields of the
8768 @samp{inet-listener} of the specific services you are interested in.
8771 @deftypevr {@code{dovecot-configuration} parameter} protocol-configuration-list protocols
8772 List of protocols we want to serve. Available protocols include
8773 @samp{imap}, @samp{pop3}, and @samp{lmtp}.
8775 Available @code{protocol-configuration} fields are:
8777 @deftypevr {@code{protocol-configuration} parameter} string name
8778 The name of the protocol.
8781 @deftypevr {@code{protocol-configuration} parameter} string auth-socket-path
8782 UNIX socket path to the master authentication server to find users.
8783 This is used by imap (for shared users) and lda.
8784 It defaults to @samp{"/var/run/dovecot/auth-userdb"}.
8787 @deftypevr {@code{protocol-configuration} parameter} space-separated-string-list mail-plugins
8788 Space separated list of plugins to load.
8791 @deftypevr {@code{protocol-configuration} parameter} non-negative-integer mail-max-userip-connections
8792 Maximum number of IMAP connections allowed for a user from each IP
8793 address. NOTE: The username is compared case-sensitively.
8794 Defaults to @samp{10}.
8799 @deftypevr {@code{dovecot-configuration} parameter} service-configuration-list services
8800 List of services to enable. Available services include @samp{imap},
8801 @samp{imap-login}, @samp{pop3}, @samp{pop3-login}, @samp{auth}, and
8804 Available @code{service-configuration} fields are:
8806 @deftypevr {@code{service-configuration} parameter} string kind
8807 The service kind. Valid values include @code{director},
8808 @code{imap-login}, @code{pop3-login}, @code{lmtp}, @code{imap},
8809 @code{pop3}, @code{auth}, @code{auth-worker}, @code{dict},
8810 @code{tcpwrap}, @code{quota-warning}, or anything else.
8813 @deftypevr {@code{service-configuration} parameter} listener-configuration-list listeners
8814 Listeners for the service. A listener is either a
8815 @code{unix-listener-configuration}, a @code{fifo-listener-configuration}, or
8816 an @code{inet-listener-configuration}.
8817 Defaults to @samp{()}.
8819 Available @code{unix-listener-configuration} fields are:
8821 @deftypevr {@code{unix-listener-configuration} parameter} file-name path
8822 The file name on which to listen.
8825 @deftypevr {@code{unix-listener-configuration} parameter} string mode
8826 The access mode for the socket.
8827 Defaults to @samp{"0600"}.
8830 @deftypevr {@code{unix-listener-configuration} parameter} string user
8831 The user to own the socket.
8832 Defaults to @samp{""}.
8835 @deftypevr {@code{unix-listener-configuration} parameter} string group
8836 The group to own the socket.
8837 Defaults to @samp{""}.
8841 Available @code{fifo-listener-configuration} fields are:
8843 @deftypevr {@code{fifo-listener-configuration} parameter} file-name path
8844 The file name on which to listen.
8847 @deftypevr {@code{fifo-listener-configuration} parameter} string mode
8848 The access mode for the socket.
8849 Defaults to @samp{"0600"}.
8852 @deftypevr {@code{fifo-listener-configuration} parameter} string user
8853 The user to own the socket.
8854 Defaults to @samp{""}.
8857 @deftypevr {@code{fifo-listener-configuration} parameter} string group
8858 The group to own the socket.
8859 Defaults to @samp{""}.
8863 Available @code{inet-listener-configuration} fields are:
8865 @deftypevr {@code{inet-listener-configuration} parameter} string protocol
8866 The protocol to listen for.
8869 @deftypevr {@code{inet-listener-configuration} parameter} string address
8870 The address on which to listen, or empty for all addresses.
8871 Defaults to @samp{""}.
8874 @deftypevr {@code{inet-listener-configuration} parameter} non-negative-integer port
8875 The port on which to listen.
8878 @deftypevr {@code{inet-listener-configuration} parameter} boolean ssl?
8879 Whether to use SSL for this service; @samp{yes}, @samp{no}, or
8881 Defaults to @samp{#t}.
8886 @deftypevr {@code{service-configuration} parameter} non-negative-integer service-count
8887 Number of connections to handle before starting a new process.
8888 Typically the only useful values are 0 (unlimited) or 1. 1 is more
8889 secure, but 0 is faster. <doc/wiki/LoginProcess.txt>.
8890 Defaults to @samp{1}.
8893 @deftypevr {@code{service-configuration} parameter} non-negative-integer process-min-avail
8894 Number of processes to always keep waiting for more connections.
8895 Defaults to @samp{0}.
8898 @deftypevr {@code{service-configuration} parameter} non-negative-integer vsz-limit
8899 If you set @samp{service-count 0}, you probably need to grow
8901 Defaults to @samp{256000000}.
8906 @deftypevr {@code{dovecot-configuration} parameter} dict-configuration dict
8907 Dict configuration, as created by the @code{dict-configuration}
8910 Available @code{dict-configuration} fields are:
8912 @deftypevr {@code{dict-configuration} parameter} free-form-fields entries
8913 A list of key-value pairs that this dict should hold.
8914 Defaults to @samp{()}.
8919 @deftypevr {@code{dovecot-configuration} parameter} passdb-configuration-list passdbs
8920 A list of passdb configurations, each one created by the
8921 @code{passdb-configuration} constructor.
8923 Available @code{passdb-configuration} fields are:
8925 @deftypevr {@code{passdb-configuration} parameter} string driver
8926 The driver that the passdb should use. Valid values include
8927 @samp{pam}, @samp{passwd}, @samp{shadow}, @samp{bsdauth}, and
8929 Defaults to @samp{"pam"}.
8932 @deftypevr {@code{passdb-configuration} parameter} free-form-args args
8933 A list of key-value args to the passdb driver.
8934 Defaults to @samp{()}.
8939 @deftypevr {@code{dovecot-configuration} parameter} userdb-configuration-list userdbs
8940 List of userdb configurations, each one created by the
8941 @code{userdb-configuration} constructor.
8943 Available @code{userdb-configuration} fields are:
8945 @deftypevr {@code{userdb-configuration} parameter} string driver
8946 The driver that the userdb should use. Valid values include
8947 @samp{passwd} and @samp{static}.
8948 Defaults to @samp{"passwd"}.
8951 @deftypevr {@code{userdb-configuration} parameter} free-form-args args
8952 A list of key-value args to the userdb driver.
8953 Defaults to @samp{()}.
8956 @deftypevr {@code{userdb-configuration} parameter} free-form-args override-fields
8957 Override fields from passwd.
8958 Defaults to @samp{()}.
8963 @deftypevr {@code{dovecot-configuration} parameter} plugin-configuration plugin-configuration
8964 Plug-in configuration, created by the @code{plugin-configuration}
8968 @deftypevr {@code{dovecot-configuration} parameter} list-of-namespace-configuration namespaces
8969 List of namespaces. Each item in the list is created by the
8970 @code{namespace-configuration} constructor.
8972 Available @code{namespace-configuration} fields are:
8974 @deftypevr {@code{namespace-configuration} parameter} string name
8975 Name for this namespace.
8978 @deftypevr {@code{namespace-configuration} parameter} string type
8979 Namespace type: @samp{private}, @samp{shared} or @samp{public}.
8980 Defaults to @samp{"private"}.
8983 @deftypevr {@code{namespace-configuration} parameter} string separator
8984 Hierarchy separator to use. You should use the same separator for
8985 all namespaces or some clients get confused. @samp{/} is usually a good
8986 one. The default however depends on the underlying mail storage
8988 Defaults to @samp{""}.
8991 @deftypevr {@code{namespace-configuration} parameter} string prefix
8992 Prefix required to access this namespace. This needs to be
8993 different for all namespaces. For example @samp{Public/}.
8994 Defaults to @samp{""}.
8997 @deftypevr {@code{namespace-configuration} parameter} string location
8998 Physical location of the mailbox. This is in the same format as
8999 mail_location, which is also the default for it.
9000 Defaults to @samp{""}.
9003 @deftypevr {@code{namespace-configuration} parameter} boolean inbox?
9004 There can be only one INBOX, and this setting defines which
9006 Defaults to @samp{#f}.
9009 @deftypevr {@code{namespace-configuration} parameter} boolean hidden?
9010 If namespace is hidden, it's not advertised to clients via NAMESPACE
9011 extension. You'll most likely also want to set @samp{list? #f}. This is mostly
9012 useful when converting from another server with different namespaces
9013 which you want to deprecate but still keep working. For example you can
9014 create hidden namespaces with prefixes @samp{~/mail/}, @samp{~%u/mail/}
9016 Defaults to @samp{#f}.
9019 @deftypevr {@code{namespace-configuration} parameter} boolean list?
9020 Show the mailboxes under this namespace with the LIST command. This
9021 makes the namespace visible for clients that do not support the NAMESPACE
9022 extension. The special @code{children} value lists child mailboxes, but
9023 hides the namespace prefix.
9024 Defaults to @samp{#t}.
9027 @deftypevr {@code{namespace-configuration} parameter} boolean subscriptions?
9028 Namespace handles its own subscriptions. If set to @code{#f}, the
9029 parent namespace handles them. The empty prefix should always have this
9031 Defaults to @samp{#t}.
9034 @deftypevr {@code{namespace-configuration} parameter} mailbox-configuration-list mailboxes
9035 List of predefined mailboxes in this namespace.
9036 Defaults to @samp{()}.
9038 Available @code{mailbox-configuration} fields are:
9040 @deftypevr {@code{mailbox-configuration} parameter} string name
9041 Name for this mailbox.
9044 @deftypevr {@code{mailbox-configuration} parameter} string auto
9045 @samp{create} will automatically create this mailbox.
9046 @samp{subscribe} will both create and subscribe to the mailbox.
9047 Defaults to @samp{"no"}.
9050 @deftypevr {@code{mailbox-configuration} parameter} space-separated-string-list special-use
9051 List of IMAP @code{SPECIAL-USE} attributes as specified by RFC 6154.
9052 Valid values are @code{\All}, @code{\Archive}, @code{\Drafts},
9053 @code{\Flagged}, @code{\Junk}, @code{\Sent}, and @code{\Trash}.
9054 Defaults to @samp{()}.
9061 @deftypevr {@code{dovecot-configuration} parameter} file-name base-dir
9062 Base directory where to store runtime data.
9063 Defaults to @samp{"/var/run/dovecot/"}.
9066 @deftypevr {@code{dovecot-configuration} parameter} string login-greeting
9067 Greeting message for clients.
9068 Defaults to @samp{"Dovecot ready."}.
9071 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-trusted-networks
9072 List of trusted network ranges. Connections from these IPs are
9073 allowed to override their IP addresses and ports (for logging and for
9074 authentication checks). @samp{disable-plaintext-auth} is also ignored
9075 for these networks. Typically you would specify your IMAP proxy servers
9077 Defaults to @samp{()}.
9080 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-access-sockets
9081 List of login access check sockets (e.g. tcpwrap).
9082 Defaults to @samp{()}.
9085 @deftypevr {@code{dovecot-configuration} parameter} boolean verbose-proctitle?
9086 Show more verbose process titles (in ps). Currently shows user name
9087 and IP address. Useful for seeing who is actually using the IMAP
9088 processes (e.g. shared mailboxes or if the same uid is used for multiple
9090 Defaults to @samp{#f}.
9093 @deftypevr {@code{dovecot-configuration} parameter} boolean shutdown-clients?
9094 Should all processes be killed when Dovecot master process shuts down.
9095 Setting this to @code{#f} means that Dovecot can be upgraded without
9096 forcing existing client connections to close (although that could also
9097 be a problem if the upgrade is e.g. due to a security fix).
9098 Defaults to @samp{#t}.
9101 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer doveadm-worker-count
9102 If non-zero, run mail commands via this many connections to doveadm
9103 server, instead of running them directly in the same process.
9104 Defaults to @samp{0}.
9107 @deftypevr {@code{dovecot-configuration} parameter} string doveadm-socket-path
9108 UNIX socket or host:port used for connecting to doveadm server.
9109 Defaults to @samp{"doveadm-server"}.
9112 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list import-environment
9113 List of environment variables that are preserved on Dovecot startup
9114 and passed down to all of its child processes. You can also give
9115 key=value pairs to always set specific settings.
9118 @deftypevr {@code{dovecot-configuration} parameter} boolean disable-plaintext-auth?
9119 Disable LOGIN command and all other plaintext authentications unless
9120 SSL/TLS is used (LOGINDISABLED capability). Note that if the remote IP
9121 matches the local IP (i.e. you're connecting from the same computer),
9122 the connection is considered secure and plaintext authentication is
9123 allowed. See also ssl=required setting.
9124 Defaults to @samp{#t}.
9127 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer auth-cache-size
9128 Authentication cache size (e.g. @samp{#e10e6}). 0 means it's disabled.
9129 Note that bsdauth, PAM and vpopmail require @samp{cache-key} to be set
9130 for caching to be used.
9131 Defaults to @samp{0}.
9134 @deftypevr {@code{dovecot-configuration} parameter} string auth-cache-ttl
9135 Time to live for cached data. After TTL expires the cached record
9136 is no longer used, *except* if the main database lookup returns internal
9137 failure. We also try to handle password changes automatically: If
9138 user's previous authentication was successful, but this one wasn't, the
9139 cache isn't used. For now this works only with plaintext
9141 Defaults to @samp{"1 hour"}.
9144 @deftypevr {@code{dovecot-configuration} parameter} string auth-cache-negative-ttl
9145 TTL for negative hits (user not found, password mismatch).
9146 0 disables caching them completely.
9147 Defaults to @samp{"1 hour"}.
9150 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list auth-realms
9151 List of realms for SASL authentication mechanisms that need them.
9152 You can leave it empty if you don't want to support multiple realms.
9153 Many clients simply use the first one listed here, so keep the default
9155 Defaults to @samp{()}.
9158 @deftypevr {@code{dovecot-configuration} parameter} string auth-default-realm
9159 Default realm/domain to use if none was specified. This is used for
9160 both SASL realms and appending @@domain to username in plaintext
9162 Defaults to @samp{""}.
9165 @deftypevr {@code{dovecot-configuration} parameter} string auth-username-chars
9166 List of allowed characters in username. If the user-given username
9167 contains a character not listed in here, the login automatically fails.
9168 This is just an extra check to make sure user can't exploit any
9169 potential quote escaping vulnerabilities with SQL/LDAP databases. If
9170 you want to allow all characters, set this value to empty.
9171 Defaults to @samp{"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890.-_@@"}.
9174 @deftypevr {@code{dovecot-configuration} parameter} string auth-username-translation
9175 Username character translations before it's looked up from
9176 databases. The value contains series of from -> to characters. For
9177 example @samp{#@@/@@} means that @samp{#} and @samp{/} characters are
9178 translated to @samp{@@}.
9179 Defaults to @samp{""}.
9182 @deftypevr {@code{dovecot-configuration} parameter} string auth-username-format
9183 Username formatting before it's looked up from databases. You can
9184 use the standard variables here, e.g. %Lu would lowercase the username,
9185 %n would drop away the domain if it was given, or @samp{%n-AT-%d} would
9186 change the @samp{@@} into @samp{-AT-}. This translation is done after
9187 @samp{auth-username-translation} changes.
9188 Defaults to @samp{"%Lu"}.
9191 @deftypevr {@code{dovecot-configuration} parameter} string auth-master-user-separator
9192 If you want to allow master users to log in by specifying the master
9193 username within the normal username string (i.e. not using SASL
9194 mechanism's support for it), you can specify the separator character
9195 here. The format is then <username><separator><master username>.
9196 UW-IMAP uses @samp{*} as the separator, so that could be a good
9198 Defaults to @samp{""}.
9201 @deftypevr {@code{dovecot-configuration} parameter} string auth-anonymous-username
9202 Username to use for users logging in with ANONYMOUS SASL
9204 Defaults to @samp{"anonymous"}.
9207 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer auth-worker-max-count
9208 Maximum number of dovecot-auth worker processes. They're used to
9209 execute blocking passdb and userdb queries (e.g. MySQL and PAM).
9210 They're automatically created and destroyed as needed.
9211 Defaults to @samp{30}.
9214 @deftypevr {@code{dovecot-configuration} parameter} string auth-gssapi-hostname
9215 Host name to use in GSSAPI principal names. The default is to use
9216 the name returned by gethostname(). Use @samp{$ALL} (with quotes) to
9217 allow all keytab entries.
9218 Defaults to @samp{""}.
9221 @deftypevr {@code{dovecot-configuration} parameter} string auth-krb5-keytab
9222 Kerberos keytab to use for the GSSAPI mechanism. Will use the
9223 system default (usually /etc/krb5.keytab) if not specified. You may
9224 need to change the auth service to run as root to be able to read this
9226 Defaults to @samp{""}.
9229 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-use-winbind?
9230 Do NTLM and GSS-SPNEGO authentication using Samba's winbind daemon
9231 and @samp{ntlm-auth} helper.
9232 <doc/wiki/Authentication/Mechanisms/Winbind.txt>.
9233 Defaults to @samp{#f}.
9236 @deftypevr {@code{dovecot-configuration} parameter} file-name auth-winbind-helper-path
9237 Path for Samba's @samp{ntlm-auth} helper binary.
9238 Defaults to @samp{"/usr/bin/ntlm_auth"}.
9241 @deftypevr {@code{dovecot-configuration} parameter} string auth-failure-delay
9242 Time to delay before replying to failed authentications.
9243 Defaults to @samp{"2 secs"}.
9246 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-ssl-require-client-cert?
9247 Require a valid SSL client certificate or the authentication
9249 Defaults to @samp{#f}.
9252 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-ssl-username-from-cert?
9253 Take the username from client's SSL certificate, using
9254 @code{X509_NAME_get_text_by_NID()} which returns the subject's DN's
9256 Defaults to @samp{#f}.
9259 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list auth-mechanisms
9260 List of wanted authentication mechanisms. Supported mechanisms are:
9261 @samp{plain}, @samp{login}, @samp{digest-md5}, @samp{cram-md5},
9262 @samp{ntlm}, @samp{rpa}, @samp{apop}, @samp{anonymous}, @samp{gssapi},
9263 @samp{otp}, @samp{skey}, and @samp{gss-spnego}. NOTE: See also
9264 @samp{disable-plaintext-auth} setting.
9267 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list director-servers
9268 List of IPs or hostnames to all director servers, including ourself.
9269 Ports can be specified as ip:port. The default port is the same as what
9270 director service's @samp{inet-listener} is using.
9271 Defaults to @samp{()}.
9274 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list director-mail-servers
9275 List of IPs or hostnames to all backend mail servers. Ranges are
9276 allowed too, like 10.0.0.10-10.0.0.30.
9277 Defaults to @samp{()}.
9280 @deftypevr {@code{dovecot-configuration} parameter} string director-user-expire
9281 How long to redirect users to a specific server after it no longer
9282 has any connections.
9283 Defaults to @samp{"15 min"}.
9286 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer director-doveadm-port
9287 TCP/IP port that accepts doveadm connections (instead of director
9288 connections) If you enable this, you'll also need to add
9289 @samp{inet-listener} for the port.
9290 Defaults to @samp{0}.
9293 @deftypevr {@code{dovecot-configuration} parameter} string director-username-hash
9294 How the username is translated before being hashed. Useful values
9295 include %Ln if user can log in with or without @@domain, %Ld if mailboxes
9296 are shared within domain.
9297 Defaults to @samp{"%Lu"}.
9300 @deftypevr {@code{dovecot-configuration} parameter} string log-path
9301 Log file to use for error messages. @samp{syslog} logs to syslog,
9302 @samp{/dev/stderr} logs to stderr.
9303 Defaults to @samp{"syslog"}.
9306 @deftypevr {@code{dovecot-configuration} parameter} string info-log-path
9307 Log file to use for informational messages. Defaults to
9309 Defaults to @samp{""}.
9312 @deftypevr {@code{dovecot-configuration} parameter} string debug-log-path
9313 Log file to use for debug messages. Defaults to
9314 @samp{info-log-path}.
9315 Defaults to @samp{""}.
9318 @deftypevr {@code{dovecot-configuration} parameter} string syslog-facility
9319 Syslog facility to use if you're logging to syslog. Usually if you
9320 don't want to use @samp{mail}, you'll use local0..local7. Also other
9321 standard facilities are supported.
9322 Defaults to @samp{"mail"}.
9325 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-verbose?
9326 Log unsuccessful authentication attempts and the reasons why they
9328 Defaults to @samp{#f}.
9331 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-verbose-passwords?
9332 In case of password mismatches, log the attempted password. Valid
9333 values are no, plain and sha1. sha1 can be useful for detecting brute
9334 force password attempts vs. user simply trying the same password over
9335 and over again. You can also truncate the value to n chars by appending
9337 Defaults to @samp{#f}.
9340 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-debug?
9341 Even more verbose logging for debugging purposes. Shows for example
9343 Defaults to @samp{#f}.
9346 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-debug-passwords?
9347 In case of password mismatches, log the passwords and used scheme so
9348 the problem can be debugged. Enabling this also enables
9350 Defaults to @samp{#f}.
9353 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-debug?
9354 Enable mail process debugging. This can help you figure out why
9355 Dovecot isn't finding your mails.
9356 Defaults to @samp{#f}.
9359 @deftypevr {@code{dovecot-configuration} parameter} boolean verbose-ssl?
9360 Show protocol level SSL errors.
9361 Defaults to @samp{#f}.
9364 @deftypevr {@code{dovecot-configuration} parameter} string log-timestamp
9365 Prefix for each line written to log file. % codes are in
9367 Defaults to @samp{"\"%b %d %H:%M:%S \""}.
9370 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-log-format-elements
9371 List of elements we want to log. The elements which have a
9372 non-empty variable value are joined together to form a comma-separated
9376 @deftypevr {@code{dovecot-configuration} parameter} string login-log-format
9377 Login log format. %s contains @samp{login-log-format-elements}
9378 string, %$ contains the data we want to log.
9379 Defaults to @samp{"%$: %s"}.
9382 @deftypevr {@code{dovecot-configuration} parameter} string mail-log-prefix
9383 Log prefix for mail processes. See doc/wiki/Variables.txt for list
9384 of possible variables you can use.
9385 Defaults to @samp{"\"%s(%u): \""}.
9388 @deftypevr {@code{dovecot-configuration} parameter} string deliver-log-format
9389 Format to use for logging mail deliveries. You can use variables:
9392 Delivery status message (e.g. @samp{saved to INBOX})
9404 Defaults to @samp{"msgid=%m: %$"}.
9407 @deftypevr {@code{dovecot-configuration} parameter} string mail-location
9408 Location for users' mailboxes. The default is empty, which means
9409 that Dovecot tries to find the mailboxes automatically. This won't work
9410 if the user doesn't yet have any mail, so you should explicitly tell
9411 Dovecot the full location.
9413 If you're using mbox, giving a path to the INBOX
9414 file (e.g. /var/mail/%u) isn't enough. You'll also need to tell Dovecot
9415 where the other mailboxes are kept. This is called the "root mail
9416 directory", and it must be the first path given in the
9417 @samp{mail-location} setting.
9419 There are a few special variables you can use, eg.:
9425 user part in user@@domain, same as %u if there's no domain
9427 domain part in user@@domain, empty if there's no domain
9432 See doc/wiki/Variables.txt for full list. Some examples:
9434 @item maildir:~/Maildir
9435 @item mbox:~/mail:INBOX=/var/mail/%u
9436 @item mbox:/var/mail/%d/%1n/%n:INDEX=/var/indexes/%d/%1n/%
9438 Defaults to @samp{""}.
9441 @deftypevr {@code{dovecot-configuration} parameter} string mail-uid
9442 System user and group used to access mails. If you use multiple,
9443 userdb can override these by returning uid or gid fields. You can use
9444 either numbers or names. <doc/wiki/UserIds.txt>.
9445 Defaults to @samp{""}.
9448 @deftypevr {@code{dovecot-configuration} parameter} string mail-gid
9450 Defaults to @samp{""}.
9453 @deftypevr {@code{dovecot-configuration} parameter} string mail-privileged-group
9454 Group to enable temporarily for privileged operations. Currently
9455 this is used only with INBOX when either its initial creation or
9456 dotlocking fails. Typically this is set to "mail" to give access to
9458 Defaults to @samp{""}.
9461 @deftypevr {@code{dovecot-configuration} parameter} string mail-access-groups
9462 Grant access to these supplementary groups for mail processes.
9463 Typically these are used to set up access to shared mailboxes. Note
9464 that it may be dangerous to set these if users can create
9465 symlinks (e.g. if "mail" group is set here, ln -s /var/mail ~/mail/var
9466 could allow a user to delete others' mailboxes, or ln -s
9467 /secret/shared/box ~/mail/mybox would allow reading it).
9468 Defaults to @samp{""}.
9471 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-full-filesystem-access?
9472 Allow full filesystem access to clients. There's no access checks
9473 other than what the operating system does for the active UID/GID. It
9474 works with both maildir and mboxes, allowing you to prefix mailboxes
9475 names with e.g. /path/ or ~user/.
9476 Defaults to @samp{#f}.
9479 @deftypevr {@code{dovecot-configuration} parameter} boolean mmap-disable?
9480 Don't use mmap() at all. This is required if you store indexes to
9481 shared filesystems (NFS or clustered filesystem).
9482 Defaults to @samp{#f}.
9485 @deftypevr {@code{dovecot-configuration} parameter} boolean dotlock-use-excl?
9486 Rely on @samp{O_EXCL} to work when creating dotlock files. NFS
9487 supports @samp{O_EXCL} since version 3, so this should be safe to use
9488 nowadays by default.
9489 Defaults to @samp{#t}.
9492 @deftypevr {@code{dovecot-configuration} parameter} string mail-fsync
9493 When to use fsync() or fdatasync() calls:
9496 Whenever necessary to avoid losing important data
9498 Useful with e.g. NFS when write()s are delayed
9500 Never use it (best performance, but crashes can lose data).
9502 Defaults to @samp{"optimized"}.
9505 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-nfs-storage?
9506 Mail storage exists in NFS. Set this to yes to make Dovecot flush
9507 NFS caches whenever needed. If you're using only a single mail server
9509 Defaults to @samp{#f}.
9512 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-nfs-index?
9513 Mail index files also exist in NFS. Setting this to yes requires
9514 @samp{mmap-disable? #t} and @samp{fsync-disable? #f}.
9515 Defaults to @samp{#f}.
9518 @deftypevr {@code{dovecot-configuration} parameter} string lock-method
9519 Locking method for index files. Alternatives are fcntl, flock and
9520 dotlock. Dotlocking uses some tricks which may create more disk I/O
9521 than other locking methods. NFS users: flock doesn't work, remember to
9522 change @samp{mmap-disable}.
9523 Defaults to @samp{"fcntl"}.
9526 @deftypevr {@code{dovecot-configuration} parameter} file-name mail-temp-dir
9527 Directory in which LDA/LMTP temporarily stores incoming mails >128
9529 Defaults to @samp{"/tmp"}.
9532 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer first-valid-uid
9533 Valid UID range for users. This is mostly to make sure that users can't
9534 log in as daemons or other system users. Note that denying root logins is
9535 hardcoded to dovecot binary and can't be done even if @samp{first-valid-uid}
9537 Defaults to @samp{500}.
9540 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer last-valid-uid
9542 Defaults to @samp{0}.
9545 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer first-valid-gid
9546 Valid GID range for users. Users having non-valid GID as primary group ID
9547 aren't allowed to log in. If user belongs to supplementary groups with
9548 non-valid GIDs, those groups are not set.
9549 Defaults to @samp{1}.
9552 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer last-valid-gid
9554 Defaults to @samp{0}.
9557 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-max-keyword-length
9558 Maximum allowed length for mail keyword name. It's only forced when
9559 trying to create new keywords.
9560 Defaults to @samp{50}.
9563 @deftypevr {@code{dovecot-configuration} parameter} colon-separated-file-name-list valid-chroot-dirs
9564 List of directories under which chrooting is allowed for mail
9565 processes (i.e. /var/mail will allow chrooting to /var/mail/foo/bar
9566 too). This setting doesn't affect @samp{login-chroot}
9567 @samp{mail-chroot} or auth chroot settings. If this setting is empty,
9568 "/./" in home dirs are ignored. WARNING: Never add directories here
9569 which local users can modify, that may lead to root exploit. Usually
9570 this should be done only if you don't allow shell access for users.
9571 <doc/wiki/Chrooting.txt>.
9572 Defaults to @samp{()}.
9575 @deftypevr {@code{dovecot-configuration} parameter} string mail-chroot
9576 Default chroot directory for mail processes. This can be overridden
9577 for specific users in user database by giving /./ in user's home
9578 directory (e.g. /home/./user chroots into /home). Note that usually
9579 there is no real need to do chrooting, Dovecot doesn't allow users to
9580 access files outside their mail directory anyway. If your home
9581 directories are prefixed with the chroot directory, append "/." to
9582 @samp{mail-chroot}. <doc/wiki/Chrooting.txt>.
9583 Defaults to @samp{""}.
9586 @deftypevr {@code{dovecot-configuration} parameter} file-name auth-socket-path
9587 UNIX socket path to master authentication server to find users.
9588 This is used by imap (for shared users) and lda.
9589 Defaults to @samp{"/var/run/dovecot/auth-userdb"}.
9592 @deftypevr {@code{dovecot-configuration} parameter} file-name mail-plugin-dir
9593 Directory where to look up mail plugins.
9594 Defaults to @samp{"/usr/lib/dovecot"}.
9597 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mail-plugins
9598 List of plugins to load for all services. Plugins specific to IMAP,
9599 LDA, etc. are added to this list in their own .conf files.
9600 Defaults to @samp{()}.
9603 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-cache-min-mail-count
9604 The minimum number of mails in a mailbox before updates are done to
9605 cache file. This allows optimizing Dovecot's behavior to do less disk
9606 writes at the cost of more disk reads.
9607 Defaults to @samp{0}.
9610 @deftypevr {@code{dovecot-configuration} parameter} string mailbox-idle-check-interval
9611 When IDLE command is running, mailbox is checked once in a while to
9612 see if there are any new mails or other changes. This setting defines
9613 the minimum time to wait between those checks. Dovecot can also use
9614 dnotify, inotify and kqueue to find out immediately when changes
9616 Defaults to @samp{"30 secs"}.
9619 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-save-crlf?
9620 Save mails with CR+LF instead of plain LF. This makes sending those
9621 mails take less CPU, especially with sendfile() syscall with Linux and
9622 FreeBSD. But it also creates a bit more disk I/O which may just make it
9623 slower. Also note that if other software reads the mboxes/maildirs,
9624 they may handle the extra CRs wrong and cause problems.
9625 Defaults to @samp{#f}.
9628 @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-stat-dirs?
9629 By default LIST command returns all entries in maildir beginning
9630 with a dot. Enabling this option makes Dovecot return only entries
9631 which are directories. This is done by stat()ing each entry, so it
9632 causes more disk I/O.
9633 (For systems setting struct @samp{dirent->d_type} this check is free
9634 and it's done always regardless of this setting).
9635 Defaults to @samp{#f}.
9638 @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-copy-with-hardlinks?
9639 When copying a message, do it with hard links whenever possible.
9640 This makes the performance much better, and it's unlikely to have any
9642 Defaults to @samp{#t}.
9645 @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-very-dirty-syncs?
9646 Assume Dovecot is the only MUA accessing Maildir: Scan cur/
9647 directory only when its mtime changes unexpectedly or when we can't find
9649 Defaults to @samp{#f}.
9652 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mbox-read-locks
9653 Which locking methods to use for locking mbox. There are four
9658 Create <mailbox>.lock file. This is the oldest and most NFS-safe
9659 solution. If you want to use /var/mail/ like directory, the users will
9660 need write access to that directory.
9662 Same as dotlock, but if it fails because of permissions or because there
9663 isn't enough disk space, just skip it.
9665 Use this if possible. Works with NFS too if lockd is used.
9667 May not exist in all systems. Doesn't work with NFS.
9669 May not exist in all systems. Doesn't work with NFS.
9672 You can use multiple locking methods; if you do the order they're declared
9673 in is important to avoid deadlocks if other MTAs/MUAs are using multiple
9674 locking methods as well. Some operating systems don't allow using some of
9675 them simultaneously.
9678 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mbox-write-locks
9682 @deftypevr {@code{dovecot-configuration} parameter} string mbox-lock-timeout
9683 Maximum time to wait for lock (all of them) before aborting.
9684 Defaults to @samp{"5 mins"}.
9687 @deftypevr {@code{dovecot-configuration} parameter} string mbox-dotlock-change-timeout
9688 If dotlock exists but the mailbox isn't modified in any way,
9689 override the lock file after this much time.
9690 Defaults to @samp{"2 mins"}.
9693 @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-dirty-syncs?
9694 When mbox changes unexpectedly we have to fully read it to find out
9695 what changed. If the mbox is large this can take a long time. Since
9696 the change is usually just a newly appended mail, it'd be faster to
9697 simply read the new mails. If this setting is enabled, Dovecot does
9698 this but still safely fallbacks to re-reading the whole mbox file
9699 whenever something in mbox isn't how it's expected to be. The only real
9700 downside to this setting is that if some other MUA changes message
9701 flags, Dovecot doesn't notice it immediately. Note that a full sync is
9702 done with SELECT, EXAMINE, EXPUNGE and CHECK commands.
9703 Defaults to @samp{#t}.
9706 @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-very-dirty-syncs?
9707 Like @samp{mbox-dirty-syncs}, but don't do full syncs even with SELECT,
9708 EXAMINE, EXPUNGE or CHECK commands. If this is set,
9709 @samp{mbox-dirty-syncs} is ignored.
9710 Defaults to @samp{#f}.
9713 @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-lazy-writes?
9714 Delay writing mbox headers until doing a full write sync (EXPUNGE
9715 and CHECK commands and when closing the mailbox). This is especially
9716 useful for POP3 where clients often delete all mails. The downside is
9717 that our changes aren't immediately visible to other MUAs.
9718 Defaults to @samp{#t}.
9721 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mbox-min-index-size
9722 If mbox size is smaller than this (e.g. 100k), don't write index
9723 files. If an index file already exists it's still read, just not
9725 Defaults to @samp{0}.
9728 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mdbox-rotate-size
9729 Maximum dbox file size until it's rotated.
9730 Defaults to @samp{2000000}.
9733 @deftypevr {@code{dovecot-configuration} parameter} string mdbox-rotate-interval
9734 Maximum dbox file age until it's rotated. Typically in days. Day
9735 begins from midnight, so 1d = today, 2d = yesterday, etc. 0 = check
9737 Defaults to @samp{"1d"}.
9740 @deftypevr {@code{dovecot-configuration} parameter} boolean mdbox-preallocate-space?
9741 When creating new mdbox files, immediately preallocate their size to
9742 @samp{mdbox-rotate-size}. This setting currently works only in Linux
9743 with some filesystems (ext4, xfs).
9744 Defaults to @samp{#f}.
9747 @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-dir
9748 sdbox and mdbox support saving mail attachments to external files,
9749 which also allows single instance storage for them. Other backends
9750 don't support this for now.
9752 WARNING: This feature hasn't been tested much yet. Use at your own risk.
9754 Directory root where to store mail attachments. Disabled, if empty.
9755 Defaults to @samp{""}.
9758 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-attachment-min-size
9759 Attachments smaller than this aren't saved externally. It's also
9760 possible to write a plugin to disable saving specific attachments
9762 Defaults to @samp{128000}.
9765 @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-fs
9766 Filesystem backend to use for saving attachments:
9769 No SiS done by Dovecot (but this might help FS's own deduplication)
9771 SiS with immediate byte-by-byte comparison during saving
9772 @item sis-queue posix
9773 SiS with delayed comparison and deduplication.
9775 Defaults to @samp{"sis posix"}.
9778 @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-hash
9779 Hash format to use in attachment filenames. You can add any text and
9780 variables: @code{%@{md4@}}, @code{%@{md5@}}, @code{%@{sha1@}},
9781 @code{%@{sha256@}}, @code{%@{sha512@}}, @code{%@{size@}}. Variables can be
9782 truncated, e.g. @code{%@{sha256:80@}} returns only first 80 bits.
9783 Defaults to @samp{"%@{sha1@}"}.
9786 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-process-limit
9788 Defaults to @samp{100}.
9791 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-client-limit
9793 Defaults to @samp{1000}.
9796 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-vsz-limit
9797 Default VSZ (virtual memory size) limit for service processes.
9798 This is mainly intended to catch and kill processes that leak memory
9799 before they eat up everything.
9800 Defaults to @samp{256000000}.
9803 @deftypevr {@code{dovecot-configuration} parameter} string default-login-user
9804 Login user is internally used by login processes. This is the most
9805 untrusted user in Dovecot system. It shouldn't have access to anything
9807 Defaults to @samp{"dovenull"}.
9810 @deftypevr {@code{dovecot-configuration} parameter} string default-internal-user
9811 Internal user is used by unprivileged processes. It should be
9812 separate from login user, so that login processes can't disturb other
9814 Defaults to @samp{"dovecot"}.
9817 @deftypevr {@code{dovecot-configuration} parameter} string ssl?
9818 SSL/TLS support: yes, no, required. <doc/wiki/SSL.txt>.
9819 Defaults to @samp{"required"}.
9822 @deftypevr {@code{dovecot-configuration} parameter} string ssl-cert
9823 PEM encoded X.509 SSL/TLS certificate (public key).
9824 Defaults to @samp{"</etc/dovecot/default.pem"}.
9827 @deftypevr {@code{dovecot-configuration} parameter} string ssl-key
9828 PEM encoded SSL/TLS private key. The key is opened before
9829 dropping root privileges, so keep the key file unreadable by anyone but
9831 Defaults to @samp{"</etc/dovecot/private/default.pem"}.
9834 @deftypevr {@code{dovecot-configuration} parameter} string ssl-key-password
9835 If key file is password protected, give the password here.
9836 Alternatively give it when starting dovecot with -p parameter. Since
9837 this file is often world-readable, you may want to place this setting
9838 instead to a different.
9839 Defaults to @samp{""}.
9842 @deftypevr {@code{dovecot-configuration} parameter} string ssl-ca
9843 PEM encoded trusted certificate authority. Set this only if you
9844 intend to use @samp{ssl-verify-client-cert? #t}. The file should
9845 contain the CA certificate(s) followed by the matching
9846 CRL(s). (e.g. @samp{ssl-ca </etc/ssl/certs/ca.pem}).
9847 Defaults to @samp{""}.
9850 @deftypevr {@code{dovecot-configuration} parameter} boolean ssl-require-crl?
9851 Require that CRL check succeeds for client certificates.
9852 Defaults to @samp{#t}.
9855 @deftypevr {@code{dovecot-configuration} parameter} boolean ssl-verify-client-cert?
9856 Request client to send a certificate. If you also want to require
9857 it, set @samp{auth-ssl-require-client-cert? #t} in auth section.
9858 Defaults to @samp{#f}.
9861 @deftypevr {@code{dovecot-configuration} parameter} string ssl-cert-username-field
9862 Which field from certificate to use for username. commonName and
9863 x500UniqueIdentifier are the usual choices. You'll also need to set
9864 @samp{auth-ssl-username-from-cert? #t}.
9865 Defaults to @samp{"commonName"}.
9868 @deftypevr {@code{dovecot-configuration} parameter} hours ssl-parameters-regenerate
9869 How often to regenerate the SSL parameters file. Generation is
9870 quite CPU intensive operation. The value is in hours, 0 disables
9871 regeneration entirely.
9872 Defaults to @samp{168}.
9875 @deftypevr {@code{dovecot-configuration} parameter} string ssl-protocols
9876 SSL protocols to use.
9877 Defaults to @samp{"!SSLv2"}.
9880 @deftypevr {@code{dovecot-configuration} parameter} string ssl-cipher-list
9882 Defaults to @samp{"ALL:!LOW:!SSLv2:!EXP:!aNULL"}.
9885 @deftypevr {@code{dovecot-configuration} parameter} string ssl-crypto-device
9886 SSL crypto device to use, for valid values run "openssl engine".
9887 Defaults to @samp{""}.
9890 @deftypevr {@code{dovecot-configuration} parameter} string postmaster-address
9891 Address to use when sending rejection mails.
9892 Default is postmaster@@<your domain>. %d expands to recipient domain.
9893 Defaults to @samp{""}.
9896 @deftypevr {@code{dovecot-configuration} parameter} string hostname
9897 Hostname to use in various parts of sent mails (e.g. in Message-Id)
9898 and in LMTP replies. Default is the system's real hostname@@domain.
9899 Defaults to @samp{""}.
9902 @deftypevr {@code{dovecot-configuration} parameter} boolean quota-full-tempfail?
9903 If user is over quota, return with temporary failure instead of
9905 Defaults to @samp{#f}.
9908 @deftypevr {@code{dovecot-configuration} parameter} file-name sendmail-path
9909 Binary to use for sending mails.
9910 Defaults to @samp{"/usr/sbin/sendmail"}.
9913 @deftypevr {@code{dovecot-configuration} parameter} string submission-host
9914 If non-empty, send mails via this SMTP host[:port] instead of
9916 Defaults to @samp{""}.
9919 @deftypevr {@code{dovecot-configuration} parameter} string rejection-subject
9920 Subject: header to use for rejection mails. You can use the same
9921 variables as for @samp{rejection-reason} below.
9922 Defaults to @samp{"Rejected: %s"}.
9925 @deftypevr {@code{dovecot-configuration} parameter} string rejection-reason
9926 Human readable error message for rejection mails. You can use
9939 Defaults to @samp{"Your message to <%t> was automatically rejected:%n%r"}.
9942 @deftypevr {@code{dovecot-configuration} parameter} string recipient-delimiter
9943 Delimiter character between local-part and detail in email
9945 Defaults to @samp{"+"}.
9948 @deftypevr {@code{dovecot-configuration} parameter} string lda-original-recipient-header
9949 Header where the original recipient address (SMTP's RCPT TO:
9950 address) is taken from if not available elsewhere. With dovecot-lda -a
9951 parameter overrides this. A commonly used header for this is
9953 Defaults to @samp{""}.
9956 @deftypevr {@code{dovecot-configuration} parameter} boolean lda-mailbox-autocreate?
9957 Should saving a mail to a nonexistent mailbox automatically create
9959 Defaults to @samp{#f}.
9962 @deftypevr {@code{dovecot-configuration} parameter} boolean lda-mailbox-autosubscribe?
9963 Should automatically created mailboxes be also automatically
9965 Defaults to @samp{#f}.
9968 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer imap-max-line-length
9969 Maximum IMAP command line length. Some clients generate very long
9970 command lines with huge mailboxes, so you may need to raise this if you
9971 get "Too long argument" or "IMAP command line too large" errors
9973 Defaults to @samp{64000}.
9976 @deftypevr {@code{dovecot-configuration} parameter} string imap-logout-format
9977 IMAP logout format string:
9980 total number of bytes read from client
9982 total number of bytes sent to client.
9984 Defaults to @samp{"in=%i out=%o"}.
9987 @deftypevr {@code{dovecot-configuration} parameter} string imap-capability
9988 Override the IMAP CAPABILITY response. If the value begins with '+',
9989 add the given capabilities on top of the defaults (e.g. +XFOO XBAR).
9990 Defaults to @samp{""}.
9993 @deftypevr {@code{dovecot-configuration} parameter} string imap-idle-notify-interval
9994 How long to wait between "OK Still here" notifications when client
9996 Defaults to @samp{"2 mins"}.
9999 @deftypevr {@code{dovecot-configuration} parameter} string imap-id-send
10000 ID field names and values to send to clients. Using * as the value
10001 makes Dovecot use the default value. The following fields have default
10002 values currently: name, version, os, os-version, support-url,
10004 Defaults to @samp{""}.
10007 @deftypevr {@code{dovecot-configuration} parameter} string imap-id-log
10008 ID fields sent by client to log. * means everything.
10009 Defaults to @samp{""}.
10012 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list imap-client-workarounds
10013 Workarounds for various client bugs:
10016 @item delay-newmail
10017 Send EXISTS/RECENT new mail notifications only when replying to NOOP and
10018 CHECK commands. Some clients ignore them otherwise, for example OSX
10019 Mail (<v2.1). Outlook Express breaks more badly though, without this it
10020 may show user "Message no longer in server" errors. Note that OE6
10021 still breaks even with this workaround if synchronization is set to
10024 @item tb-extra-mailbox-sep
10025 Thunderbird gets somehow confused with LAYOUT=fs (mbox and dbox) and
10026 adds extra @samp{/} suffixes to mailbox names. This option causes Dovecot to
10027 ignore the extra @samp{/} instead of treating it as invalid mailbox name.
10029 @item tb-lsub-flags
10030 Show \Noselect flags for LSUB replies with LAYOUT=fs (e.g. mbox).
10031 This makes Thunderbird realize they aren't selectable and show them
10032 greyed out, instead of only later giving "not selectable" popup error.
10034 Defaults to @samp{()}.
10037 @deftypevr {@code{dovecot-configuration} parameter} string imap-urlauth-host
10038 Host allowed in URLAUTH URLs sent by client. "*" allows all.
10039 Defaults to @samp{""}.
10043 Whew! Lots of configuration options. The nice thing about it though is
10044 that GuixSD has a complete interface to Dovecot's configuration
10045 language. This allows not only a nice way to declare configurations,
10046 but also offers reflective capabilities as well: users can write code to
10047 inspect and transform configurations from within Scheme.
10049 However, it could be that you just want to get a @code{dovecot.conf} up
10050 and running. In that case, you can pass an
10051 @code{opaque-dovecot-configuration} as the @code{#:config} parameter to
10052 @code{dovecot-service}. As its name indicates, an opaque configuration
10053 does not have easy reflective capabilities.
10055 Available @code{opaque-dovecot-configuration} fields are:
10057 @deftypevr {@code{opaque-dovecot-configuration} parameter} package dovecot
10058 The dovecot package.
10061 @deftypevr {@code{opaque-dovecot-configuration} parameter} string string
10062 The contents of the @code{dovecot.conf}, as a string.
10065 For example, if your @code{dovecot.conf} is just the empty string, you
10066 could instantiate a dovecot service like this:
10069 (dovecot-service #:config
10070 (opaque-dovecot-configuration
10075 @subsubsection Web Services
10077 The @code{(gnu services web)} module provides the following service:
10079 @deffn {Scheme Procedure} nginx-service [#:nginx nginx] @
10080 [#:log-directory ``/var/log/nginx''] @
10081 [#:run-directory ``/var/run/nginx''] @
10084 Return a service that runs @var{nginx}, the nginx web server.
10086 The nginx daemon loads its runtime configuration from @var{config-file}.
10087 Log files are written to @var{log-directory} and temporary runtime data
10088 files are written to @var{run-directory}. For proper operation, these
10089 arguments should match what is in @var{config-file} to ensure that the
10090 directories are created when the service is activated.
10094 @node Various Services
10095 @subsubsection Various Services
10098 @subsubheading RPC Bind Service
10101 The @code{(gnu services nfs)} module provides the following:
10103 @defvr {Scheme Variable} rpcbind-service-type
10104 A service type for the RPC portmapper daemon.
10108 @deftp {Data Type} rpcbind-configuration
10109 Data type representing the configuration of the RPC Bind Service.
10110 This type has the following parameters:
10112 @item @code{rpcbind} (default: @code{rpcbind})
10113 The rpcbind package to use.
10115 @item @code{warm-start?} (default: @code{#t})
10116 If this parameter is @code{#t}, then the daemon will read a
10117 state file on startup thus reloading state information saved by a previous
10123 @subsubheading Lirc Service
10125 The @code{(gnu services lirc)} module provides the following service.
10127 @deffn {Scheme Procedure} lirc-service [#:lirc lirc] @
10128 [#:device #f] [#:driver #f] [#:config-file #f] @
10129 [#:extra-options '()]
10130 Return a service that runs @url{http://www.lirc.org,LIRC}, a daemon that
10131 decodes infrared signals from remote controls.
10133 Optionally, @var{device}, @var{driver} and @var{config-file}
10134 (configuration file name) may be specified. See @command{lircd} manual
10137 Finally, @var{extra-options} is a list of additional command-line options
10138 passed to @command{lircd}.
10142 @subsubheading Spice Service
10144 The @code{(gnu services spice)} module provides the following service.
10146 @deffn {Scheme Procedure} spice-vdagent-service [#:spice-vdagent]
10147 Returns a service that runs @url{http://www.spice-space.org,VDAGENT}, a daemon
10148 that enables sharing the clipboard with a vm and setting the guest display
10149 resolution when the graphical console window resizes.
10152 @subsubsection Dictionary Services
10153 The @code{(gnu services dict)} module provides the following service:
10155 @deffn {Scheme Procedure} dicod-service [#:config (dicod-configuration)]
10156 Return a service that runs the @command{dicod} daemon, an implementation
10157 of DICT server (@pxref{Dicod,,, dico, GNU Dico Manual}).
10159 The optional @var{config} argument specifies the configuration for
10160 @command{dicod}, which should be a @code{<dicod-configuration>} object, by
10161 default it serves the GNU Collaborative International Dictonary of English.
10163 You can add @command{open localhost} to your @file{~/.dico} file to make
10164 @code{localhost} the default server for @command{dico} client
10165 (@pxref{Initialization File,,, dico, GNU Dico Manual}).
10168 @deftp {Data Type} dicod-configuration
10169 Data type representing the configuration of dicod.
10172 @item @code{dico} (default: @var{dico})
10173 Package object of the GNU Dico dictionary server.
10175 @item @code{interfaces} (default: @var{'("localhost")})
10176 This is the list of IP addresses and ports and possibly socket file
10177 names to listen to (@pxref{Server Settings, @code{listen} directive,,
10178 dico, GNU Dico Manual}).
10180 @item @code{databases} (default: @var{(list %dicod-database:gcide)})
10181 List of @code{<dicod-database>} objects denoting dictionaries to be served.
10185 @deftp {Data Type} dicod-database
10186 Data type representing a dictionary database.
10190 Name of the database, will be used in DICT commands.
10192 @item @code{module}
10193 Name of the dicod module used by this database
10194 (@pxref{Modules,,, dico, GNU Dico Manual}).
10196 @item @code{options}
10197 List of strings or gexps representing the arguments for the module handler
10198 (@pxref{Handlers,,, dico, GNU Dico Manual}).
10202 @defvr {Scheme Variable} %dicod-database:gcide
10203 A @code{<dicod-database>} object serving the GNU Collaborative International
10204 Dictonary of English using the @code{gcide} package.
10207 @node Setuid Programs
10208 @subsection Setuid Programs
10210 @cindex setuid programs
10211 Some programs need to run with ``root'' privileges, even when they are
10212 launched by unprivileged users. A notorious example is the
10213 @command{passwd} program, which users can run to change their
10214 password, and which needs to access the @file{/etc/passwd} and
10215 @file{/etc/shadow} files---something normally restricted to root, for
10216 obvious security reasons. To address that, these executables are
10217 @dfn{setuid-root}, meaning that they always run with root privileges
10218 (@pxref{How Change Persona,,, libc, The GNU C Library Reference Manual},
10219 for more info about the setuid mechanism.)
10221 The store itself @emph{cannot} contain setuid programs: that would be a
10222 security issue since any user on the system can write derivations that
10223 populate the store (@pxref{The Store}). Thus, a different mechanism is
10224 used: instead of changing the setuid bit directly on files that are in
10225 the store, we let the system administrator @emph{declare} which programs
10226 should be setuid root.
10228 The @code{setuid-programs} field of an @code{operating-system}
10229 declaration contains a list of G-expressions denoting the names of
10230 programs to be setuid-root (@pxref{Using the Configuration System}).
10231 For instance, the @command{passwd} program, which is part of the Shadow
10232 package, can be designated by this G-expression (@pxref{G-Expressions}):
10235 #~(string-append #$shadow "/bin/passwd")
10238 A default set of setuid programs is defined by the
10239 @code{%setuid-programs} variable of the @code{(gnu system)} module.
10241 @defvr {Scheme Variable} %setuid-programs
10242 A list of G-expressions denoting common programs that are setuid-root.
10244 The list includes commands such as @command{passwd}, @command{ping},
10245 @command{su}, and @command{sudo}.
10248 Under the hood, the actual setuid programs are created in the
10249 @file{/run/setuid-programs} directory at system activation time. The
10250 files in this directory refer to the ``real'' binaries, which are in the
10253 @node X.509 Certificates
10254 @subsection X.509 Certificates
10256 @cindex HTTPS, certificates
10257 @cindex X.509 certificates
10259 Web servers available over HTTPS (that is, HTTP over the transport-layer
10260 security mechanism, TLS) send client programs an @dfn{X.509 certificate}
10261 that the client can then use to @emph{authenticate} the server. To do
10262 that, clients verify that the server's certificate is signed by a
10263 so-called @dfn{certificate authority} (CA). But to verify the CA's
10264 signature, clients must have first acquired the CA's certificate.
10266 Web browsers such as GNU@tie{}IceCat include their own set of CA
10267 certificates, such that they are able to verify CA signatures
10270 However, most other programs that can talk HTTPS---@command{wget},
10271 @command{git}, @command{w3m}, etc.---need to be told where CA
10272 certificates can be found.
10274 @cindex @code{nss-certs}
10275 In GuixSD, this is done by adding a package that provides certificates
10276 to the @code{packages} field of the @code{operating-system} declaration
10277 (@pxref{operating-system Reference}). GuixSD includes one such package,
10278 @code{nss-certs}, which is a set of CA certificates provided as part of
10279 Mozilla's Network Security Services.
10281 Note that it is @emph{not} part of @var{%base-packages}, so you need to
10282 explicitly add it. The @file{/etc/ssl/certs} directory, which is where
10283 most applications and libraries look for certificates by default, points
10284 to the certificates installed globally.
10286 Unprivileged users, including users of Guix on a foreign distro,
10287 can also install their own certificate package in
10288 their profile. A number of environment variables need to be defined so
10289 that applications and libraries know where to find them. Namely, the
10290 OpenSSL library honors the @code{SSL_CERT_DIR} and @code{SSL_CERT_FILE}
10291 variables. Some applications add their own environment variables; for
10292 instance, the Git version control system honors the certificate bundle
10293 pointed to by the @code{GIT_SSL_CAINFO} environment variable. Thus, you
10294 would typically run something like:
10297 $ guix package -i nss-certs
10298 $ export SSL_CERT_DIR="$HOME/.guix-profile/etc/ssl/certs"
10299 $ export SSL_CERT_FILE="$HOME/.guix-profile/etc/ssl/certs/ca-certificates.crt"
10300 $ export GIT_SSL_CAINFO="$SSL_CERT_FILE"
10303 @node Name Service Switch
10304 @subsection Name Service Switch
10306 @cindex name service switch
10308 The @code{(gnu system nss)} module provides bindings to the
10309 configuration file of the libc @dfn{name service switch} or @dfn{NSS}
10310 (@pxref{NSS Configuration File,,, libc, The GNU C Library Reference
10311 Manual}). In a nutshell, the NSS is a mechanism that allows libc to be
10312 extended with new ``name'' lookup methods for system databases, which
10313 includes host names, service names, user accounts, and more (@pxref{Name
10314 Service Switch, System Databases and Name Service Switch,, libc, The GNU
10315 C Library Reference Manual}).
10317 The NSS configuration specifies, for each system database, which lookup
10318 method is to be used, and how the various methods are chained
10319 together---for instance, under which circumstances NSS should try the
10320 next method in the list. The NSS configuration is given in the
10321 @code{name-service-switch} field of @code{operating-system} declarations
10322 (@pxref{operating-system Reference, @code{name-service-switch}}).
10325 @cindex .local, host name lookup
10326 As an example, the declaration below configures the NSS to use the
10327 @uref{http://0pointer.de/lennart/projects/nss-mdns/, @code{nss-mdns}
10328 back-end}, which supports host name lookups over multicast DNS (mDNS)
10329 for host names ending in @code{.local}:
10332 (name-service-switch
10333 (hosts (list %files ;first, check /etc/hosts
10335 ;; If the above did not succeed, try
10336 ;; with 'mdns_minimal'.
10338 (name "mdns_minimal")
10340 ;; 'mdns_minimal' is authoritative for
10341 ;; '.local'. When it returns "not found",
10342 ;; no need to try the next methods.
10343 (reaction (lookup-specification
10344 (not-found => return))))
10346 ;; Then fall back to DNS.
10350 ;; Finally, try with the "full" 'mdns'.
10355 Do not worry: the @code{%mdns-host-lookup-nss} variable (see below)
10356 contains this configuration, so you will not have to type it if all you
10357 want is to have @code{.local} host lookup working.
10359 Note that, in this case, in addition to setting the
10360 @code{name-service-switch} of the @code{operating-system} declaration,
10361 you also need to use @code{avahi-service} (@pxref{Networking Services,
10362 @code{avahi-service}}), or @var{%desktop-services}, which includes it
10363 (@pxref{Desktop Services}). Doing this makes @code{nss-mdns} accessible
10364 to the name service cache daemon (@pxref{Base Services,
10365 @code{nscd-service}}).
10367 For convenience, the following variables provide typical NSS
10370 @defvr {Scheme Variable} %default-nss
10371 This is the default name service switch configuration, a
10372 @code{name-service-switch} object.
10375 @defvr {Scheme Variable} %mdns-host-lookup-nss
10376 This is the name service switch configuration with support for host name
10377 lookup over multicast DNS (mDNS) for host names ending in @code{.local}.
10380 The reference for name service switch configuration is given below. It
10381 is a direct mapping of the configuration file format of the C library , so
10382 please refer to the C library manual for more information (@pxref{NSS
10383 Configuration File,,, libc, The GNU C Library Reference Manual}).
10384 Compared to the configuration file format of libc NSS, it has the advantage
10385 not only of adding this warm parenthetic feel that we like, but also
10386 static checks: you will know about syntax errors and typos as soon as you
10387 run @command{guix system}.
10389 @deftp {Data Type} name-service-switch
10391 This is the data type representation the configuration of libc's name
10392 service switch (NSS). Each field below represents one of the supported
10409 The system databases handled by the NSS. Each of these fields must be a
10410 list of @code{<name-service>} objects (see below).
10414 @deftp {Data Type} name-service
10416 This is the data type representing an actual name service and the
10417 associated lookup action.
10421 A string denoting the name service (@pxref{Services in the NSS
10422 configuration,,, libc, The GNU C Library Reference Manual}).
10424 Note that name services listed here must be visible to nscd. This is
10425 achieved by passing the @code{#:name-services} argument to
10426 @code{nscd-service} the list of packages providing the needed name
10427 services (@pxref{Base Services, @code{nscd-service}}).
10430 An action specified using the @code{lookup-specification} macro
10431 (@pxref{Actions in the NSS configuration,,, libc, The GNU C Library
10432 Reference Manual}). For example:
10435 (lookup-specification (unavailable => continue)
10436 (success => return))
10441 @node Initial RAM Disk
10442 @subsection Initial RAM Disk
10444 @cindex initial RAM disk (initrd)
10445 @cindex initrd (initial RAM disk)
10446 For bootstrapping purposes, the Linux-Libre kernel is passed an
10447 @dfn{initial RAM disk}, or @dfn{initrd}. An initrd contains a temporary
10448 root file system as well as an initialization script. The latter is
10449 responsible for mounting the real root file system, and for loading any
10450 kernel modules that may be needed to achieve that.
10452 The @code{initrd} field of an @code{operating-system} declaration allows
10453 you to specify which initrd you would like to use. The @code{(gnu
10454 system linux-initrd)} module provides two ways to build an initrd: the
10455 high-level @code{base-initrd} procedure, and the low-level
10456 @code{expression->initrd} procedure.
10458 The @code{base-initrd} procedure is intended to cover most common uses.
10459 For example, if you want to add a bunch of kernel modules to be loaded
10460 at boot time, you can define the @code{initrd} field of the operating
10461 system declaration like this:
10464 (initrd (lambda (file-systems . rest)
10465 ;; Create a standard initrd that has modules "foo.ko"
10466 ;; and "bar.ko", as well as their dependencies, in
10467 ;; addition to the modules available by default.
10468 (apply base-initrd file-systems
10469 #:extra-modules '("foo" "bar")
10473 The @code{base-initrd} procedure also handles common use cases that
10474 involves using the system as a QEMU guest, or as a ``live'' system with
10475 volatile root file system.
10477 The initial RAM disk produced by @code{base-initrd} honors several
10478 options passed on the Linux kernel command line (that is, arguments
10479 passed @i{via} the @code{linux} command of GRUB, or the
10480 @code{-append} option) of QEMU, notably:
10483 @item --load=@var{boot}
10484 Tell the initial RAM disk to load @var{boot}, a file containing a Scheme
10485 program, once it has mounted the root file system.
10487 GuixSD uses this option to yield control to a boot program that runs the
10488 service activation programs and then spawns the GNU@tie{}Shepherd, the
10489 initialization system.
10491 @item --root=@var{root}
10492 Mount @var{root} as the root file system. @var{root} can be a
10493 device name like @code{/dev/sda1}, a partition label, or a partition
10496 @item --system=@var{system}
10497 Have @file{/run/booted-system} and @file{/run/current-system} point to
10500 @item modprobe.blacklist=@var{modules}@dots{}
10501 @cindex module, black-listing
10502 @cindex black list, of kernel modules
10503 Instruct the initial RAM disk as well as the @command{modprobe} command
10504 (from the kmod package) to refuse to load @var{modules}. @var{modules}
10505 must be a comma-separated list of module names---e.g.,
10506 @code{usbkbd,9pnet}.
10509 Start a read-eval-print loop (REPL) from the initial RAM disk before it
10510 tries to load kernel modules and to mount the root file system. Our
10511 marketing team calls it @dfn{boot-to-Guile}. The Schemer in you will
10512 love it. @xref{Using Guile Interactively,,, guile, GNU Guile Reference
10513 Manual}, for more information on Guile's REPL.
10517 Now that you know all the features that initial RAM disks produced by
10518 @code{base-initrd} provide, here is how to use it and customize it
10521 @deffn {Monadic Procedure} base-initrd @var{file-systems} @
10522 [#:qemu-networking? #f] [#:virtio? #t] [#:volatile-root? #f] @
10523 [#:extra-modules '()] [#:mapped-devices '()]
10524 Return a monadic derivation that builds a generic initrd. @var{file-systems} is
10525 a list of file systems to be mounted by the initrd, possibly in addition to
10526 the root file system specified on the kernel command line via @code{--root}.
10527 @var{mapped-devices} is a list of device mappings to realize before
10528 @var{file-systems} are mounted (@pxref{Mapped Devices}).
10530 When @var{qemu-networking?} is true, set up networking with the standard QEMU
10531 parameters. When @var{virtio?} is true, load additional modules so that the
10532 initrd can be used as a QEMU guest with para-virtualized I/O drivers.
10534 When @var{volatile-root?} is true, the root file system is writable but any changes
10537 The initrd is automatically populated with all the kernel modules necessary
10538 for @var{file-systems} and for the given options. However, additional kernel
10539 modules can be listed in @var{extra-modules}. They will be added to the initrd, and
10540 loaded at boot time in the order in which they appear.
10543 Needless to say, the initrds we produce and use embed a
10544 statically-linked Guile, and the initialization program is a Guile
10545 program. That gives a lot of flexibility. The
10546 @code{expression->initrd} procedure builds such an initrd, given the
10547 program to run in that initrd.
10549 @deffn {Monadic Procedure} expression->initrd @var{exp} @
10550 [#:guile %guile-static-stripped] [#:name "guile-initrd"]
10551 Return a derivation that builds a Linux initrd (a gzipped cpio archive)
10552 containing @var{guile} and that evaluates @var{exp}, a G-expression,
10553 upon booting. All the derivations referenced by @var{exp} are
10554 automatically copied to the initrd.
10557 @node GRUB Configuration
10558 @subsection GRUB Configuration
10561 @cindex boot loader
10563 The operating system uses GNU@tie{}GRUB as its boot loader
10564 (@pxref{Overview, overview of GRUB,, grub, GNU GRUB Manual}). It is
10565 configured using a @code{grub-configuration} declaration. This data type
10566 is exported by the @code{(gnu system grub)} module and described below.
10568 @deftp {Data Type} grub-configuration
10569 The type of a GRUB configuration declaration.
10573 @item @code{device}
10574 This is a string denoting the boot device. It must be a device name
10575 understood by the @command{grub-install} command, such as
10576 @code{/dev/sda} or @code{(hd0)} (@pxref{Invoking grub-install,,, grub,
10579 @item @code{menu-entries} (default: @code{()})
10580 A possibly empty list of @code{menu-entry} objects (see below), denoting
10581 entries to appear in the GRUB boot menu, in addition to the current
10582 system entry and the entry pointing to previous system generations.
10584 @item @code{default-entry} (default: @code{0})
10585 The index of the default boot menu entry. Index 0 is for the entry of the
10588 @item @code{timeout} (default: @code{5})
10589 The number of seconds to wait for keyboard input before booting. Set to
10590 0 to boot immediately, and to -1 to wait indefinitely.
10592 @item @code{theme} (default: @var{%default-theme})
10593 The @code{grub-theme} object describing the theme to use.
10598 Should you want to list additional boot menu entries @i{via} the
10599 @code{menu-entries} field above, you will need to create them with the
10600 @code{menu-entry} form:
10602 @deftp {Data Type} menu-entry
10603 The type of an entry in the GRUB boot menu.
10608 The label to show in the menu---e.g., @code{"GNU"}.
10611 The Linux kernel to boot.
10613 @item @code{linux-arguments} (default: @code{()})
10614 The list of extra Linux kernel command-line arguments---e.g.,
10615 @code{("console=ttyS0")}.
10617 @item @code{initrd}
10618 A G-Expression or string denoting the file name of the initial RAM disk
10619 to use (@pxref{G-Expressions}).
10624 @c FIXME: Write documentation once it's stable.
10625 Themes are created using the @code{grub-theme} form, which is not
10628 @defvr {Scheme Variable} %default-theme
10629 This is the default GRUB theme used by the operating system, with a
10630 fancy background image displaying the GNU and Guix logos.
10634 @node Invoking guix system
10635 @subsection Invoking @code{guix system}
10637 Once you have written an operating system declaration as seen in the
10638 previous section, it can be @dfn{instantiated} using the @command{guix
10639 system} command. The synopsis is:
10642 guix system @var{options}@dots{} @var{action} @var{file}
10645 @var{file} must be the name of a file containing an
10646 @code{operating-system} declaration. @var{action} specifies how the
10647 operating system is instantiated. Currently the following values are
10652 Build the operating system described in @var{file}, activate it, and
10653 switch to it@footnote{This action is usable only on systems already
10656 This effects all the configuration specified in @var{file}: user
10657 accounts, system services, global package list, setuid programs, etc.
10658 The command starts system services specified in @var{file} that are not
10659 currently running; if a service is currently running, it does not
10660 attempt to upgrade it since this would not be possible without stopping it
10663 It also adds a GRUB menu entry for the new OS configuration, and moves
10664 entries for older configurations to a submenu---unless
10665 @option{--no-grub} is passed.
10668 @c The paragraph below refers to the problem discussed at
10669 @c <http://lists.gnu.org/archive/html/guix-devel/2014-08/msg00057.html>.
10670 It is highly recommended to run @command{guix pull} once before you run
10671 @command{guix system reconfigure} for the first time (@pxref{Invoking
10672 guix pull}). Failing to do that you would see an older version of Guix
10673 once @command{reconfigure} has completed.
10677 Build the derivation of the operating system, which includes all the
10678 configuration files and programs needed to boot and run the system.
10679 This action does not actually install anything.
10682 Populate the given directory with all the files necessary to run the
10683 operating system specified in @var{file}. This is useful for first-time
10684 installations of GuixSD. For instance:
10687 guix system init my-os-config.scm /mnt
10690 copies to @file{/mnt} all the store items required by the configuration
10691 specified in @file{my-os-config.scm}. This includes configuration
10692 files, packages, and so on. It also creates other essential files
10693 needed for the system to operate correctly---e.g., the @file{/etc},
10694 @file{/var}, and @file{/run} directories, and the @file{/bin/sh} file.
10696 This command also installs GRUB on the device specified in
10697 @file{my-os-config}, unless the @option{--no-grub} option was passed.
10700 @cindex virtual machine
10702 @anchor{guix system vm}
10703 Build a virtual machine that contains the operating system declared in
10704 @var{file}, and return a script to run that virtual machine (VM).
10705 Arguments given to the script are passed to QEMU.
10707 The VM shares its store with the host system.
10709 Additional file systems can be shared between the host and the VM using
10710 the @code{--share} and @code{--expose} command-line options: the former
10711 specifies a directory to be shared with write access, while the latter
10712 provides read-only access to the shared directory.
10714 The example below creates a VM in which the user's home directory is
10715 accessible read-only, and where the @file{/exchange} directory is a
10716 read-write mapping of @file{$HOME/tmp} on the host:
10719 guix system vm my-config.scm \
10720 --expose=$HOME --share=$HOME/tmp=/exchange
10723 On GNU/Linux, the default is to boot directly to the kernel; this has
10724 the advantage of requiring only a very tiny root disk image since the
10725 store of the host can then be mounted.
10727 The @code{--full-boot} option forces a complete boot sequence, starting
10728 with the bootloader. This requires more disk space since a root image
10729 containing at least the kernel, initrd, and bootloader data files must
10730 be created. The @code{--image-size} option can be used to specify the
10735 Return a virtual machine or disk image of the operating system declared
10736 in @var{file} that stands alone. Use the @option{--image-size} option
10737 to specify the size of the image.
10739 When using @code{vm-image}, the returned image is in qcow2 format, which
10740 the QEMU emulator can efficiently use. @xref{Running GuixSD in a VM},
10741 for more information on how to run the image in a virtual machine.
10743 When using @code{disk-image}, a raw disk image is produced; it can be
10744 copied as is to a USB stick, for instance. Assuming @code{/dev/sdc} is
10745 the device corresponding to a USB stick, one can copy the image to it
10746 using the following command:
10749 # dd if=$(guix system disk-image my-os.scm) of=/dev/sdc
10753 Return a script to run the operating system declared in @var{file}
10754 within a container. Containers are a set of lightweight isolation
10755 mechanisms provided by the kernel Linux-libre. Containers are
10756 substantially less resource-demanding than full virtual machines since
10757 the kernel, shared objects, and other resources can be shared with the
10758 host system; this also means they provide thinner isolation.
10760 Currently, the script must be run as root in order to support more than
10761 a single user and group. The container shares its store with the host
10764 As with the @code{vm} action (@pxref{guix system vm}), additional file
10765 systems to be shared between the host and container can be specified
10766 using the @option{--share} and @option{--expose} options:
10769 guix system container my-config.scm \
10770 --expose=$HOME --share=$HOME/tmp=/exchange
10774 This option requires Linux-libre 3.19 or newer.
10779 @var{options} can contain any of the common build options (@pxref{Common
10780 Build Options}). In addition, @var{options} can contain one of the
10784 @item --system=@var{system}
10785 @itemx -s @var{system}
10786 Attempt to build for @var{system} instead of the host system type.
10787 This works as per @command{guix build} (@pxref{Invoking guix build}).
10791 Return the derivation file name of the given operating system without
10794 @item --image-size=@var{size}
10795 For the @code{vm-image} and @code{disk-image} actions, create an image
10796 of the given @var{size}. @var{size} may be a number of bytes, or it may
10797 include a unit as a suffix (@pxref{Block size, size specifications,,
10798 coreutils, GNU Coreutils}).
10800 @item --on-error=@var{strategy}
10801 Apply @var{strategy} when an error occurs when reading @var{file}.
10802 @var{strategy} may be one of the following:
10805 @item nothing-special
10806 Report the error concisely and exit. This is the default strategy.
10809 Likewise, but also display a backtrace.
10812 Report the error and enter Guile's debugger. From there, you can run
10813 commands such as @code{,bt} to get a backtrace, @code{,locals} to
10814 display local variable values, and more generally inspect the state of the
10815 program. @xref{Debug Commands,,, guile, GNU Guile Reference Manual}, for
10816 a list of available debugging commands.
10821 All the actions above, except @code{build} and @code{init},
10822 can use KVM support in the Linux-libre kernel. Specifically, if the
10823 machine has hardware virtualization support, the corresponding
10824 KVM kernel module should be loaded, and the @file{/dev/kvm} device node
10825 must exist and be readable and writable by the user and by the
10826 build users of the daemon (@pxref{Build Environment Setup}).
10829 Once you have built, configured, re-configured, and re-re-configured
10830 your GuixSD installation, you may find it useful to list the operating
10831 system generations available on disk---and that you can choose from the
10836 @item list-generations
10837 List a summary of each generation of the operating system available on
10838 disk, in a human-readable way. This is similar to the
10839 @option{--list-generations} option of @command{guix package}
10840 (@pxref{Invoking guix package}).
10842 Optionally, one can specify a pattern, with the same syntax that is used
10843 in @command{guix package --list-generations}, to restrict the list of
10844 generations displayed. For instance, the following command displays
10845 generations that are up to 10 days old:
10848 $ guix system list-generations 10d
10853 The @command{guix system} command has even more to offer! The following
10854 sub-commands allow you to visualize how your system services relate to
10857 @anchor{system-extension-graph}
10860 @item extension-graph
10861 Emit in Dot/Graphviz format to standard output the @dfn{service
10862 extension graph} of the operating system defined in @var{file}
10863 (@pxref{Service Composition}, for more information on service
10869 $ guix system extension-graph @var{file} | dot -Tpdf > services.pdf
10872 produces a PDF file showing the extension relations among services.
10874 @anchor{system-shepherd-graph}
10875 @item shepherd-graph
10876 Emit in Dot/Graphviz format to standard output the @dfn{dependency
10877 graph} of shepherd services of the operating system defined in
10878 @var{file}. @xref{Shepherd Services}, for more information and for an
10883 @node Running GuixSD in a VM
10884 @subsection Running GuixSD in a Virtual Machine
10886 One way to run GuixSD in a virtual machine (VM) is to build a GuixSD
10887 virtual machine image using @command{guix system vm-image}
10888 (@pxref{Invoking guix system}). The returned image is in qcow2 format,
10889 which the @uref{http://qemu.org/, QEMU emulator} can efficiently use.
10891 To run the image in QEMU, copy it out of the store (@pxref{The Store})
10892 and give yourself permission to write to the copy. When invoking QEMU,
10893 you must choose a system emulator that is suitable for your hardware
10894 platform. Here is a minimal QEMU invocation that will boot the result
10895 of @command{guix system vm-image} on x86_64 hardware:
10898 $ qemu-system-x86_64 \
10899 -net user -net nic,model=virtio \
10900 -enable-kvm -m 256 /tmp/qemu-image
10903 Here is what each of these options means:
10906 @item qemu-system-x86_64
10907 This specifies the hardware platform to emulate. This should match the
10911 Enable the unprivileged user-mode network stack. The guest OS can
10912 access the host but not vice versa. This is the simplest way to get the
10913 guest OS online. If you do not choose a network stack, the boot will
10916 @item -net nic,model=virtio
10917 You must create a network interface of a given model. If you do not
10918 create a NIC, the boot will fail. Assuming your hardware platform is
10919 x86_64, you can get a list of available NIC models by running
10920 @command{qemu-system-x86_64 -net nic,model=help}.
10923 If your system has hardware virtualization extensions, enabling the
10924 virtual machine support (KVM) of the Linux kernel will make things run
10928 RAM available to the guest OS, in mebibytes. Defaults to 128@tie{}MiB,
10929 which may be insufficient for some operations.
10931 @item /tmp/qemu-image
10932 The file name of the qcow2 image.
10935 @node Defining Services
10936 @subsection Defining Services
10938 The previous sections show the available services and how one can combine
10939 them in an @code{operating-system} declaration. But how do we define
10940 them in the first place? And what is a service anyway?
10943 * Service Composition:: The model for composing services.
10944 * Service Types and Services:: Types and services.
10945 * Service Reference:: API reference.
10946 * Shepherd Services:: A particular type of service.
10949 @node Service Composition
10950 @subsubsection Service Composition
10954 Here we define a @dfn{service} as, broadly, something that extends the
10955 functionality of the operating system. Often a service is a process---a
10956 @dfn{daemon}---started when the system boots: a secure shell server, a
10957 Web server, the Guix build daemon, etc. Sometimes a service is a daemon
10958 whose execution can be triggered by another daemon---e.g., an FTP server
10959 started by @command{inetd} or a D-Bus service activated by
10960 @command{dbus-daemon}. Occasionally, a service does not map to a
10961 daemon. For instance, the ``account'' service collects user accounts
10962 and makes sure they exist when the system runs; the ``udev'' service
10963 collects device management rules and makes them available to the eudev
10964 daemon; the @file{/etc} service populates the @file{/etc} directory
10967 @cindex service extensions
10968 GuixSD services are connected by @dfn{extensions}. For instance, the
10969 secure shell service @emph{extends} the Shepherd---the GuixSD
10970 initialization system, running as PID@tie{}1---by giving it the command
10971 lines to start and stop the secure shell daemon (@pxref{Networking
10972 Services, @code{lsh-service}}); the UPower service extends the D-Bus
10973 service by passing it its @file{.service} specification, and extends the
10974 udev service by passing it device management rules (@pxref{Desktop
10975 Services, @code{upower-service}}); the Guix daemon service extends the
10976 Shepherd by passing it the command lines to start and stop the daemon,
10977 and extends the account service by passing it a list of required build
10978 user accounts (@pxref{Base Services}).
10980 All in all, services and their ``extends'' relations form a directed
10981 acyclic graph (DAG). If we represent services as boxes and extensions
10982 as arrows, a typical system might provide something like this:
10984 @image{images/service-graph,,5in,Typical service extension graph.}
10986 @cindex system service
10987 At the bottom, we see the @dfn{system service}, which produces the
10988 directory containing everything to run and boot the system, as returned
10989 by the @command{guix system build} command. @xref{Service Reference},
10990 to learn about the other service types shown here.
10991 @xref{system-extension-graph, the @command{guix system extension-graph}
10992 command}, for information on how to generate this representation for a
10993 particular operating system definition.
10995 @cindex service types
10996 Technically, developers can define @dfn{service types} to express these
10997 relations. There can be any number of services of a given type on the
10998 system---for instance, a system running two instances of the GNU secure
10999 shell server (lsh) has two instances of @var{lsh-service-type}, with
11000 different parameters.
11002 The following section describes the programming interface for service
11003 types and services.
11005 @node Service Types and Services
11006 @subsubsection Service Types and Services
11008 A @dfn{service type} is a node in the DAG described above. Let us start
11009 with a simple example, the service type for the Guix build daemon
11010 (@pxref{Invoking guix-daemon}):
11013 (define guix-service-type
11017 (list (service-extension shepherd-root-service-type guix-shepherd-service)
11018 (service-extension account-service-type guix-accounts)
11019 (service-extension activation-service-type guix-activation)))))
11023 It defines two things:
11027 A name, whose sole purpose is to make inspection and debugging easier.
11030 A list of @dfn{service extensions}, where each extension designates the
11031 target service type and a procedure that, given the parameters of the
11032 service, returns a list of objects to extend the service of that type.
11034 Every service type has at least one service extension. The only
11035 exception is the @dfn{boot service type}, which is the ultimate service.
11038 In this example, @var{guix-service-type} extends three services:
11041 @item shepherd-root-service-type
11042 The @var{guix-shepherd-service} procedure defines how the Shepherd
11043 service is extended. Namely, it returns a @code{<shepherd-service>}
11044 object that defines how @command{guix-daemon} is started and stopped
11045 (@pxref{Shepherd Services}).
11047 @item account-service-type
11048 This extension for this service is computed by @var{guix-accounts},
11049 which returns a list of @code{user-group} and @code{user-account}
11050 objects representing the build user accounts (@pxref{Invoking
11053 @item activation-service-type
11054 Here @var{guix-activation} is a procedure that returns a gexp, which is
11055 a code snippet to run at ``activation time''---e.g., when the service is
11059 A service of this type is instantiated like this:
11062 (service guix-service-type
11063 (guix-configuration
11065 (use-substitutes? #f)))
11068 The second argument to the @code{service} form is a value representing
11069 the parameters of this specific service instance.
11070 @xref{guix-configuration-type, @code{guix-configuration}}, for
11071 information about the @code{guix-configuration} data type.
11073 @var{guix-service-type} is quite simple because it extends other
11074 services but is not extensible itself.
11076 @c @subsubsubsection Extensible Service Types
11078 The service type for an @emph{extensible} service looks like this:
11081 (define udev-service-type
11082 (service-type (name 'udev)
11084 (list (service-extension shepherd-root-service-type
11085 udev-shepherd-service)))
11087 (compose concatenate) ;concatenate the list of rules
11088 (extend (lambda (config rules)
11090 (($ <udev-configuration> udev initial-rules)
11091 (udev-configuration
11092 (udev udev) ;the udev package to use
11093 (rules (append initial-rules rules)))))))))
11096 This is the service type for the
11097 @uref{https://wiki.gentoo.org/wiki/Project:Eudev, eudev device
11098 management daemon}. Compared to the previous example, in addition to an
11099 extension of @var{shepherd-root-service-type}, we see two new fields:
11103 This is the procedure to @dfn{compose} the list of extensions to
11104 services of this type.
11106 Services can extend the udev service by passing it lists of rules; we
11107 compose those extensions simply by concatenating them.
11110 This procedure defines how the value of the service is @dfn{extended} with
11111 the composition of the extensions.
11113 Udev extensions are composed into a list of rules, but the udev service
11114 value is itself a @code{<udev-configuration>} record. So here, we
11115 extend that record by appending the list of rules it contains to the
11116 list of contributed rules.
11119 There can be only one instance of an extensible service type such as
11120 @var{udev-service-type}. If there were more, the
11121 @code{service-extension} specifications would be ambiguous.
11123 Still here? The next section provides a reference of the programming
11124 interface for services.
11126 @node Service Reference
11127 @subsubsection Service Reference
11129 We have seen an overview of service types (@pxref{Service Types and
11130 Services}). This section provides a reference on how to manipulate
11131 services and service types. This interface is provided by the
11132 @code{(gnu services)} module.
11134 @deffn {Scheme Procedure} service @var{type} @var{value}
11135 Return a new service of @var{type}, a @code{<service-type>} object (see
11136 below.) @var{value} can be any object; it represents the parameters of
11137 this particular service instance.
11140 @deffn {Scheme Procedure} service? @var{obj}
11141 Return true if @var{obj} is a service.
11144 @deffn {Scheme Procedure} service-kind @var{service}
11145 Return the type of @var{service}---i.e., a @code{<service-type>} object.
11148 @deffn {Scheme Procedure} service-parameters @var{service}
11149 Return the value associated with @var{service}. It represents its
11153 Here is an example of how a service is created and manipulated:
11157 (service nginx-service-type
11158 (nginx-configuration
11160 (log-directory log-directory)
11161 (run-directory run-directory)
11162 (file config-file))))
11167 (eq? (service-kind s) nginx-service-type)
11171 The @code{modify-services} form provides a handy way to change the
11172 parameters of some of the services of a list such as
11173 @var{%base-services} (@pxref{Base Services, @code{%base-services}}). It
11174 evaluates to a list of services. Of course, you could always use
11175 standard list combinators such as @code{map} and @code{fold} to do that
11176 (@pxref{SRFI-1, List Library,, guile, GNU Guile Reference Manual});
11177 @code{modify-services} simply provides a more concise form for this
11180 @deffn {Scheme Syntax} modify-services @var{services} @
11181 (@var{type} @var{variable} => @var{body}) @dots{}
11183 Modify the services listed in @var{services} according to the given
11184 clauses. Each clause has the form:
11187 (@var{type} @var{variable} => @var{body})
11190 where @var{type} is a service type---e.g.,
11191 @code{guix-service-type}---and @var{variable} is an identifier that is
11192 bound within the @var{body} to the service parameters---e.g., a
11193 @code{guix-configuration} instance---of the original service of that
11196 The @var{body} should evaluate to the new service parameters, which will
11197 be used to configure the new service. This new service will replace the
11198 original in the resulting list. Because a service's service parameters
11199 are created using @code{define-record-type*}, you can write a succinct
11200 @var{body} that evaluates to the new service parameters by using the
11201 @code{inherit} feature that @code{define-record-type*} provides.
11203 @xref{Using the Configuration System}, for example usage.
11207 Next comes the programming interface for service types. This is
11208 something you want to know when writing new service definitions, but not
11209 necessarily when simply looking for ways to customize your
11210 @code{operating-system} declaration.
11212 @deftp {Data Type} service-type
11213 @cindex service type
11214 This is the representation of a @dfn{service type} (@pxref{Service Types
11219 This is a symbol, used only to simplify inspection and debugging.
11221 @item @code{extensions}
11222 A non-empty list of @code{<service-extension>} objects (see below).
11224 @item @code{compose} (default: @code{#f})
11225 If this is @code{#f}, then the service type denotes services that cannot
11226 be extended---i.e., services that do not receive ``values'' from other
11229 Otherwise, it must be a one-argument procedure. The procedure is called
11230 by @code{fold-services} and is passed a list of values collected from
11231 extensions. It must return a value that is a valid parameter value for
11232 the service instance.
11234 @item @code{extend} (default: @code{#f})
11235 If this is @code{#f}, services of this type cannot be extended.
11237 Otherwise, it must be a two-argument procedure: @code{fold-services}
11238 calls it, passing it the initial value of the service as the first argument
11239 and the result of applying @code{compose} to the extension values as the
11243 @xref{Service Types and Services}, for examples.
11246 @deffn {Scheme Procedure} service-extension @var{target-type} @
11248 Return a new extension for services of type @var{target-type}.
11249 @var{compute} must be a one-argument procedure: @code{fold-services}
11250 calls it, passing it the value associated with the service that provides
11251 the extension; it must return a valid value for the target service.
11254 @deffn {Scheme Procedure} service-extension? @var{obj}
11255 Return true if @var{obj} is a service extension.
11258 At the core of the service abstraction lies the @code{fold-services}
11259 procedure, which is responsible for ``compiling'' a list of services
11260 down to a single directory that contains everything needed to boot and
11261 run the system---the directory shown by the @command{guix system build}
11262 command (@pxref{Invoking guix system}). In essence, it propagates
11263 service extensions down the service graph, updating each node parameters
11264 on the way, until it reaches the root node.
11266 @deffn {Scheme Procedure} fold-services @var{services} @
11267 [#:target-type @var{system-service-type}]
11268 Fold @var{services} by propagating their extensions down to the root of
11269 type @var{target-type}; return the root service adjusted accordingly.
11272 Lastly, the @code{(gnu services)} module also defines several essential
11273 service types, some of which are listed below.
11275 @defvr {Scheme Variable} system-service-type
11276 This is the root of the service graph. It produces the system directory
11277 as returned by the @command{guix system build} command.
11280 @defvr {Scheme Variable} boot-service-type
11281 The type of the ``boot service'', which produces the @dfn{boot script}.
11282 The boot script is what the initial RAM disk runs when booting.
11285 @defvr {Scheme Variable} etc-service-type
11286 The type of the @file{/etc} service. This service can be extended by
11287 passing it name/file tuples such as:
11290 (list `("issue" ,(plain-file "issue" "Welcome!\n")))
11293 In this example, the effect would be to add an @file{/etc/issue} file
11294 pointing to the given file.
11297 @defvr {Scheme Variable} setuid-program-service-type
11298 Type for the ``setuid-program service''. This service collects lists of
11299 executable file names, passed as gexps, and adds them to the set of
11300 setuid-root programs on the system (@pxref{Setuid Programs}).
11303 @defvr {Scheme Variable} profile-service-type
11304 Type of the service that populates the @dfn{system profile}---i.e., the
11305 programs under @file{/run/current-system/profile}. Other services can
11306 extend it by passing it lists of packages to add to the system profile.
11310 @node Shepherd Services
11311 @subsubsection Shepherd Services
11314 @cindex init system
11315 The @code{(gnu services shepherd)} module provides a way to define
11316 services managed by the GNU@tie{}Shepherd, which is the GuixSD
11317 initialization system---the first process that is started when the
11318 system boots, also known as PID@tie{}1
11319 (@pxref{Introduction,,, shepherd, The GNU Shepherd Manual}).
11321 Services in the Shepherd can depend on each other. For instance, the
11322 SSH daemon may need to be started after the syslog daemon has been
11323 started, which in turn can only happen once all the file systems have
11324 been mounted. The simple operating system defined earlier (@pxref{Using
11325 the Configuration System}) results in a service graph like this:
11327 @image{images/shepherd-graph,,5in,Typical shepherd service graph.}
11329 You can actually generate such a graph for any operating system
11330 definition using the @command{guix system shepherd-graph} command
11331 (@pxref{system-shepherd-graph, @command{guix system shepherd-graph}}).
11333 The @var{%shepherd-root-service} is a service object representing
11334 PID@tie{}1, of type @var{shepherd-root-service-type}; it can be extended
11335 by passing it lists of @code{<shepherd-service>} objects.
11337 @deftp {Data Type} shepherd-service
11338 The data type representing a service managed by the Shepherd.
11341 @item @code{provision}
11342 This is a list of symbols denoting what the service provides.
11344 These are the names that may be passed to @command{herd start},
11345 @command{herd status}, and similar commands (@pxref{Invoking herd,,,
11346 shepherd, The GNU Shepherd Manual}). @xref{Slots of services, the
11347 @code{provides} slot,, shepherd, The GNU Shepherd Manual}, for details.
11349 @item @code{requirements} (default: @code{'()})
11350 List of symbols denoting the Shepherd services this one depends on.
11352 @item @code{respawn?} (default: @code{#t})
11353 Whether to restart the service when it stops, for instance when the
11354 underlying process dies.
11357 @itemx @code{stop} (default: @code{#~(const #f)})
11358 The @code{start} and @code{stop} fields refer to the Shepherd's
11359 facilities to start and stop processes (@pxref{Service De- and
11360 Constructors,,, shepherd, The GNU Shepherd Manual}). They are given as
11361 G-expressions that get expanded in the Shepherd configuration file
11362 (@pxref{G-Expressions}).
11364 @item @code{documentation}
11365 A documentation string, as shown when running:
11368 herd doc @var{service-name}
11371 where @var{service-name} is one of the symbols in @var{provision}
11372 (@pxref{Invoking herd,,, shepherd, The GNU Shepherd Manual}).
11374 @item @code{modules} (default: @var{%default-modules})
11375 This is the list of modules that must be in scope when @code{start} and
11376 @code{stop} are evaluated.
11381 @defvr {Scheme Variable} shepherd-root-service-type
11382 The service type for the Shepherd ``root service''---i.e., PID@tie{}1.
11384 This is the service type that extensions target when they want to create
11385 shepherd services (@pxref{Service Types and Services}, for an example).
11386 Each extension must pass a list of @code{<shepherd-service>}.
11389 @defvr {Scheme Variable} %shepherd-root-service
11390 This service represents PID@tie{}1.
11394 @node Installing Debugging Files
11395 @section Installing Debugging Files
11397 @cindex debugging files
11398 Program binaries, as produced by the GCC compilers for instance, are
11399 typically written in the ELF format, with a section containing
11400 @dfn{debugging information}. Debugging information is what allows the
11401 debugger, GDB, to map binary code to source code; it is required to
11402 debug a compiled program in good conditions.
11404 The problem with debugging information is that is takes up a fair amount
11405 of disk space. For example, debugging information for the GNU C Library
11406 weighs in at more than 60 MiB. Thus, as a user, keeping all the
11407 debugging info of all the installed programs is usually not an option.
11408 Yet, space savings should not come at the cost of an impediment to
11409 debugging---especially in the GNU system, which should make it easier
11410 for users to exert their computing freedom (@pxref{GNU Distribution}).
11412 Thankfully, the GNU Binary Utilities (Binutils) and GDB provide a
11413 mechanism that allows users to get the best of both worlds: debugging
11414 information can be stripped from the binaries and stored in separate
11415 files. GDB is then able to load debugging information from those files,
11416 when they are available (@pxref{Separate Debug Files,,, gdb, Debugging
11419 The GNU distribution takes advantage of this by storing debugging
11420 information in the @code{lib/debug} sub-directory of a separate package
11421 output unimaginatively called @code{debug} (@pxref{Packages with
11422 Multiple Outputs}). Users can choose to install the @code{debug} output
11423 of a package when they need it. For instance, the following command
11424 installs the debugging information for the GNU C Library and for GNU
11428 guix package -i glibc:debug guile:debug
11431 GDB must then be told to look for debug files in the user's profile, by
11432 setting the @code{debug-file-directory} variable (consider setting it
11433 from the @file{~/.gdbinit} file, @pxref{Startup,,, gdb, Debugging with
11437 (gdb) set debug-file-directory ~/.guix-profile/lib/debug
11440 From there on, GDB will pick up debugging information from the
11441 @code{.debug} files under @file{~/.guix-profile/lib/debug}.
11443 In addition, you will most likely want GDB to be able to show the source
11444 code being debugged. To do that, you will have to unpack the source
11445 code of the package of interest (obtained with @code{guix build
11446 --source}, @pxref{Invoking guix build}), and to point GDB to that source
11447 directory using the @code{directory} command (@pxref{Source Path,
11448 @code{directory},, gdb, Debugging with GDB}).
11450 @c XXX: keep me up-to-date
11451 The @code{debug} output mechanism in Guix is implemented by the
11452 @code{gnu-build-system} (@pxref{Build Systems}). Currently, it is
11453 opt-in---debugging information is available only for the packages
11454 with definitions explicitly declaring a @code{debug} output. This may be
11455 changed to opt-out in the future if our build farm servers can handle
11456 the load. To check whether a package has a @code{debug} output, use
11457 @command{guix package --list-available} (@pxref{Invoking guix package}).
11460 @node Security Updates
11461 @section Security Updates
11463 @cindex security updates
11464 @cindex security vulnerabilities
11465 Occasionally, important security vulnerabilities are discovered in software
11466 packages and must be patched. Guix developers try hard to keep track of
11467 known vulnerabilities and to apply fixes as soon as possible in the
11468 @code{master} branch of Guix (we do not yet provide a ``stable'' branch
11469 containing only security updates.) The @command{guix lint} tool helps
11470 developers find out about vulnerable versions of software packages in the
11475 gnu/packages/base.scm:652:2: glibc-2.21: probably vulnerable to CVE-2015-1781, CVE-2015-7547
11476 gnu/packages/gcc.scm:334:2: gcc-4.9.3: probably vulnerable to CVE-2015-5276
11477 gnu/packages/image.scm:312:2: openjpeg-2.1.0: probably vulnerable to CVE-2016-1923, CVE-2016-1924
11481 @xref{Invoking guix lint}, for more information.
11484 As of version @value{VERSION}, the feature described below is considered
11488 Guix follows a functional
11489 package management discipline (@pxref{Introduction}), which implies
11490 that, when a package is changed, @emph{every package that depends on it}
11491 must be rebuilt. This can significantly slow down the deployment of
11492 fixes in core packages such as libc or Bash, since basically the whole
11493 distribution would need to be rebuilt. Using pre-built binaries helps
11494 (@pxref{Substitutes}), but deployment may still take more time than
11498 To address this, Guix implements @dfn{grafts}, a mechanism that allows
11499 for fast deployment of critical updates without the costs associated
11500 with a whole-distribution rebuild. The idea is to rebuild only the
11501 package that needs to be patched, and then to ``graft'' it onto packages
11502 explicitly installed by the user and that were previously referring to
11503 the original package. The cost of grafting is typically very low, and
11504 order of magnitudes lower than a full rebuild of the dependency chain.
11506 @cindex replacements of packages, for grafts
11507 For instance, suppose a security update needs to be applied to Bash.
11508 Guix developers will provide a package definition for the ``fixed''
11509 Bash, say @var{bash-fixed}, in the usual way (@pxref{Defining
11510 Packages}). Then, the original package definition is augmented with a
11511 @code{replacement} field pointing to the package containing the bug fix:
11518 (replacement bash-fixed)))
11521 From there on, any package depending directly or indirectly on Bash---as
11522 reported by @command{guix gc --requisites} (@pxref{Invoking guix
11523 gc})---that is installed is automatically ``rewritten'' to refer to
11524 @var{bash-fixed} instead of @var{bash}. This grafting process takes
11525 time proportional to the size of the package, usually less than a
11526 minute for an ``average'' package on a recent machine. Grafting is
11527 recursive: when an indirect dependency requires grafting, then grafting
11528 ``propagates'' up to the package that the user is installing.
11530 Currently, the graft and the package it replaces (@var{bash-fixed} and
11531 @var{bash} in the example above) must have the exact same @code{name}
11532 and @code{version} fields. This restriction mostly comes from the fact
11533 that grafting works by patching files, including binary files, directly.
11534 Other restrictions may apply: for instance, when adding a graft to a
11535 package providing a shared library, the original shared library and its
11536 replacement must have the same @code{SONAME} and be binary-compatible.
11538 The @option{--no-grafts} command-line option allows you to forcefully
11539 avoid grafting (@pxref{Common Build Options, @option{--no-grafts}}).
11543 guix build bash --no-grafts
11547 returns the store file name of the original Bash, whereas:
11554 returns the store file name of the ``fixed'', replacement Bash. This
11555 allows you to distinguish between the two variants of Bash.
11557 To verify which Bash your whole profile refers to, you can run
11558 (@pxref{Invoking guix gc}):
11561 guix gc -R `readlink -f ~/.guix-profile` | grep bash
11565 @dots{} and compare the store file names that you get with those above.
11566 Likewise for a complete GuixSD system generation:
11569 guix gc -R `guix system build my-config.scm` | grep bash
11572 Lastly, to check which Bash running processes are using, you can use the
11573 @command{lsof} command:
11576 lsof | grep /gnu/store/.*bash
11580 @node Package Modules
11581 @section Package Modules
11583 From a programming viewpoint, the package definitions of the
11584 GNU distribution are provided by Guile modules in the @code{(gnu packages
11585 @dots{})} name space@footnote{Note that packages under the @code{(gnu
11586 packages @dots{})} module name space are not necessarily ``GNU
11587 packages''. This module naming scheme follows the usual Guile module
11588 naming convention: @code{gnu} means that these modules are distributed
11589 as part of the GNU system, and @code{packages} identifies modules that
11590 define packages.} (@pxref{Modules, Guile modules,, guile, GNU Guile
11591 Reference Manual}). For instance, the @code{(gnu packages emacs)}
11592 module exports a variable named @code{emacs}, which is bound to a
11593 @code{<package>} object (@pxref{Defining Packages}).
11595 The @code{(gnu packages @dots{})} module name space is
11596 automatically scanned for packages by the command-line tools. For
11597 instance, when running @code{guix package -i emacs}, all the @code{(gnu
11598 packages @dots{})} modules are scanned until one that exports a package
11599 object whose name is @code{emacs} is found. This package search
11600 facility is implemented in the @code{(gnu packages)} module.
11602 @cindex customization, of packages
11603 @cindex package module search path
11604 Users can store package definitions in modules with different
11605 names---e.g., @code{(my-packages emacs)}@footnote{Note that the file
11606 name and module name must match. For instance, the @code{(my-packages
11607 emacs)} module must be stored in a @file{my-packages/emacs.scm} file
11608 relative to the load path specified with @option{--load-path} or
11609 @code{GUIX_PACKAGE_PATH}. @xref{Modules and the File System,,,
11610 guile, GNU Guile Reference Manual}, for details.}. These package definitions
11611 will not be visible by default. Users can invoke commands such as
11612 @command{guix package} and @command{guix build} with the
11613 @code{-e} option so that they know where to find the package. Better
11614 yet, they can use the
11615 @code{-L} option of these commands to make those modules visible
11616 (@pxref{Invoking guix build, @code{--load-path}}), or define the
11617 @code{GUIX_PACKAGE_PATH} environment variable. This environment
11618 variable makes it easy to extend or customize the distribution and is
11619 honored by all the user interfaces.
11621 @defvr {Environment Variable} GUIX_PACKAGE_PATH
11622 This is a colon-separated list of directories to search for additional
11623 package modules. Directories listed in this variable take precedence
11624 over the own modules of the distribution.
11627 The distribution is fully @dfn{bootstrapped} and @dfn{self-contained}:
11628 each package is built based solely on other packages in the
11629 distribution. The root of this dependency graph is a small set of
11630 @dfn{bootstrap binaries}, provided by the @code{(gnu packages
11631 bootstrap)} module. For more information on bootstrapping,
11632 @pxref{Bootstrapping}.
11634 @node Packaging Guidelines
11635 @section Packaging Guidelines
11637 The GNU distribution is nascent and may well lack some of your favorite
11638 packages. This section describes how you can help make the distribution
11639 grow. @xref{Contributing}, for additional information on how you can
11642 Free software packages are usually distributed in the form of
11643 @dfn{source code tarballs}---typically @file{tar.gz} files that contain
11644 all the source files. Adding a package to the distribution means
11645 essentially two things: adding a @dfn{recipe} that describes how to
11646 build the package, including a list of other packages required to build
11647 it, and adding @dfn{package metadata} along with that recipe, such as a
11648 description and licensing information.
11650 In Guix all this information is embodied in @dfn{package definitions}.
11651 Package definitions provide a high-level view of the package. They are
11652 written using the syntax of the Scheme programming language; in fact,
11653 for each package we define a variable bound to the package definition,
11654 and export that variable from a module (@pxref{Package Modules}).
11655 However, in-depth Scheme knowledge is @emph{not} a prerequisite for
11656 creating packages. For more information on package definitions,
11657 @pxref{Defining Packages}.
11659 Once a package definition is in place, stored in a file in the Guix
11660 source tree, it can be tested using the @command{guix build} command
11661 (@pxref{Invoking guix build}). For example, assuming the new package is
11662 called @code{gnew}, you may run this command from the Guix build tree
11663 (@pxref{Running Guix Before It Is Installed}):
11666 ./pre-inst-env guix build gnew --keep-failed
11669 Using @code{--keep-failed} makes it easier to debug build failures since
11670 it provides access to the failed build tree. Another useful
11671 command-line option when debugging is @code{--log-file}, to access the
11674 If the package is unknown to the @command{guix} command, it may be that
11675 the source file contains a syntax error, or lacks a @code{define-public}
11676 clause to export the package variable. To figure it out, you may load
11677 the module from Guile to get more information about the actual error:
11680 ./pre-inst-env guile -c '(use-modules (gnu packages gnew))'
11683 Once your package builds correctly, please send us a patch
11684 (@pxref{Contributing}). Well, if you need help, we will be happy to
11685 help you too. Once the patch is committed in the Guix repository, the
11686 new package automatically gets built on the supported platforms by
11687 @url{http://hydra.gnu.org/jobset/gnu/master, our continuous integration
11690 @cindex substituter
11691 Users can obtain the new package definition simply by running
11692 @command{guix pull} (@pxref{Invoking guix pull}). When
11693 @code{hydra.gnu.org} is done building the package, installing the
11694 package automatically downloads binaries from there
11695 (@pxref{Substitutes}). The only place where human intervention is
11696 needed is to review and apply the patch.
11700 * Software Freedom:: What may go into the distribution.
11701 * Package Naming:: What's in a name?
11702 * Version Numbers:: When the name is not enough.
11703 * Synopses and Descriptions:: Helping users find the right package.
11704 * Python Modules:: Taming the snake.
11705 * Perl Modules:: Little pearls.
11706 * Java Packages:: Coffee break.
11707 * Fonts:: Fond of fonts.
11710 @node Software Freedom
11711 @subsection Software Freedom
11713 @c Adapted from http://www.gnu.org/philosophy/philosophy.html.
11715 The GNU operating system has been developed so that users can have
11716 freedom in their computing. GNU is @dfn{free software}, meaning that
11717 users have the @url{http://www.gnu.org/philosophy/free-sw.html,four
11718 essential freedoms}: to run the program, to study and change the program
11719 in source code form, to redistribute exact copies, and to distribute
11720 modified versions. Packages found in the GNU distribution provide only
11721 software that conveys these four freedoms.
11723 In addition, the GNU distribution follow the
11724 @url{http://www.gnu.org/distros/free-system-distribution-guidelines.html,free
11725 software distribution guidelines}. Among other things, these guidelines
11726 reject non-free firmware, recommendations of non-free software, and
11727 discuss ways to deal with trademarks and patents.
11729 Some otherwise free upstream package sources contain a small and optional
11730 subset that violates the above guidelines, for instance because this subset
11731 is itself non-free code. When that happens, the offending items are removed
11732 with appropriate patches or code snippets in the @code{origin} form of the
11733 package (@pxref{Defining Packages}). This way, @code{guix
11734 build --source} returns the ``freed'' source rather than the unmodified
11738 @node Package Naming
11739 @subsection Package Naming
11741 A package has actually two names associated with it:
11742 First, there is the name of the @emph{Scheme variable}, the one following
11743 @code{define-public}. By this name, the package can be made known in the
11744 Scheme code, for instance as input to another package. Second, there is
11745 the string in the @code{name} field of a package definition. This name
11746 is used by package management commands such as
11747 @command{guix package} and @command{guix build}.
11749 Both are usually the same and correspond to the lowercase conversion of
11750 the project name chosen upstream, with underscores replaced with
11751 hyphens. For instance, GNUnet is available as @code{gnunet}, and
11752 SDL_net as @code{sdl-net}.
11754 We do not add @code{lib} prefixes for library packages, unless these are
11755 already part of the official project name. But @pxref{Python
11756 Modules} and @ref{Perl Modules} for special rules concerning modules for
11757 the Python and Perl languages.
11759 Font package names are handled differently, @pxref{Fonts}.
11762 @node Version Numbers
11763 @subsection Version Numbers
11765 We usually package only the latest version of a given free software
11766 project. But sometimes, for instance for incompatible library versions,
11767 two (or more) versions of the same package are needed. These require
11768 different Scheme variable names. We use the name as defined
11769 in @ref{Package Naming}
11770 for the most recent version; previous versions use the same name, suffixed
11771 by @code{-} and the smallest prefix of the version number that may
11772 distinguish the two versions.
11774 The name inside the package definition is the same for all versions of a
11775 package and does not contain any version number.
11777 For instance, the versions 2.24.20 and 3.9.12 of GTK+ may be packaged as follows:
11780 (define-public gtk+
11785 (define-public gtk+-2
11788 (version "2.24.20")
11791 If we also wanted GTK+ 3.8.2, this would be packaged as
11793 (define-public gtk+-3.8
11800 @c See <https://lists.gnu.org/archive/html/guix-devel/2016-01/msg00425.html>,
11801 @c for a discussion of what follows.
11802 @cindex version number, for VCS snapshots
11803 Occasionally, we package snapshots of upstream's version control system
11804 (VCS) instead of formal releases. This should remain exceptional,
11805 because it is up to upstream developers to clarify what the stable
11806 release is. Yet, it is sometimes necessary. So, what should we put in
11807 the @code{version} field?
11809 Clearly, we need to make the commit identifier of the VCS snapshot
11810 visible in the version string, but we also need to make sure that the
11811 version string is monotonically increasing so that @command{guix package
11812 --upgrade} can determine which version is newer. Since commit
11813 identifiers, notably with Git, are not monotonically increasing, we add
11814 a revision number that we increase each time we upgrade to a newer
11815 snapshot. The resulting version string looks like this:
11820 | | `-- upstream commit ID
11822 | `--- Guix package revision
11824 latest upstream version
11827 It is a good idea to strip commit identifiers in the @code{version}
11828 field to, say, 7 digits. It avoids an aesthetic annoyance (assuming
11829 aesthetics have a role to play here) as well as problems related to OS
11830 limits such as the maximum shebang length (127 bytes for the Linux
11831 kernel.) It is best to use the full commit identifiers in
11832 @code{origin}s, though, to avoid ambiguities. A typical package
11833 definition may look like this:
11837 (let ((commit "c3f29bc928d5900971f65965feaae59e1272a3f7")
11838 (revision "1")) ;Guix package revision
11840 (version (string-append "0.9-" revision "."
11841 (string-take commit 7)))
11844 (uri (git-reference
11845 (url "git://example.org/my-package.git")
11847 (sha256 (base32 "1mbikn@dots{}"))
11848 (file-name (string-append "my-package-" version
11854 @node Synopses and Descriptions
11855 @subsection Synopses and Descriptions
11857 As we have seen before, each package in GNU@tie{}Guix includes a
11858 synopsis and a description (@pxref{Defining Packages}). Synopses and
11859 descriptions are important: They are what @command{guix package
11860 --search} searches, and a crucial piece of information to help users
11861 determine whether a given package suits their needs. Consequently,
11862 packagers should pay attention to what goes into them.
11864 Synopses must start with a capital letter and must not end with a
11865 period. They must not start with ``a'' or ``the'', which usually does
11866 not bring anything; for instance, prefer ``File-frobbing tool'' over ``A
11867 tool that frobs files''. The synopsis should say what the package
11868 is---e.g., ``Core GNU utilities (file, text, shell)''---or what it is
11869 used for---e.g., the synopsis for GNU@tie{}grep is ``Print lines
11870 matching a pattern''.
11872 Keep in mind that the synopsis must be meaningful for a very wide
11873 audience. For example, ``Manipulate alignments in the SAM format''
11874 might make sense for a seasoned bioinformatics researcher, but might be
11875 fairly unhelpful or even misleading to a non-specialized audience. It
11876 is a good idea to come up with a synopsis that gives an idea of the
11877 application domain of the package. In this example, this might give
11878 something like ``Manipulate nucleotide sequence alignments'', which
11879 hopefully gives the user a better idea of whether this is what they are
11882 Descriptions should take between five and ten lines. Use full
11883 sentences, and avoid using acronyms without first introducing them.
11884 Please avoid marketing phrases such as ``world-leading'',
11885 ``industrial-strength'', and ``next-generation'', and avoid superlatives
11886 like ``the most advanced''---they are not helpful to users looking for a
11887 package and may even sound suspicious. Instead, try to be factual,
11888 mentioning use cases and features.
11890 @cindex Texinfo markup, in package descriptions
11891 Descriptions can include Texinfo markup, which is useful to introduce
11892 ornaments such as @code{@@code} or @code{@@dfn}, bullet lists, or
11893 hyperlinks (@pxref{Overview,,, texinfo, GNU Texinfo}). However you
11894 should be careful when using some characters for example @samp{@@} and
11895 curly braces which are the basic special characters in Texinfo
11896 (@pxref{Special Characters,,, texinfo, GNU Texinfo}). User interfaces
11897 such as @command{guix package --show} take care of rendering it
11900 Synopses and descriptions are translated by volunteers
11901 @uref{http://translationproject.org/domain/guix-packages.html, at the
11902 Translation Project} so that as many users as possible can read them in
11903 their native language. User interfaces search them and display them in
11904 the language specified by the current locale.
11906 Translation is a lot of work so, as a packager, please pay even more
11907 attention to your synopses and descriptions as every change may entail
11908 additional work for translators. In order to help them, it is possible
11909 to make recommendations or instructions visible to them by inserting
11910 special comments like this (@pxref{xgettext Invocation,,, gettext, GNU
11914 ;; TRANSLATORS: "X11 resize-and-rotate" should not be translated.
11915 (description "ARandR is designed to provide a simple visual front end
11916 for the X11 resize-and-rotate (RandR) extension. @dots{}")
11920 @node Python Modules
11921 @subsection Python Modules
11923 We currently package Python 2 and Python 3, under the Scheme variable names
11924 @code{python-2} and @code{python} as explained in @ref{Version Numbers}.
11925 To avoid confusion and naming clashes with other programming languages, it
11926 seems desirable that the name of a package for a Python module contains
11927 the word @code{python}.
11929 Some modules are compatible with only one version of Python, others with both.
11930 If the package Foo compiles only with Python 3, we name it
11931 @code{python-foo}; if it compiles only with Python 2, we name it
11932 @code{python2-foo}. If it is compatible with both versions, we create two
11933 packages with the corresponding names.
11935 If a project already contains the word @code{python}, we drop this;
11936 for instance, the module python-dateutil is packaged under the names
11937 @code{python-dateutil} and @code{python2-dateutil}. If the project name
11938 starts with @code{py} (e.g. @code{pytz}), we keep it and prefix it as
11943 @subsection Perl Modules
11945 Perl programs standing for themselves are named as any other package,
11946 using the lowercase upstream name.
11947 For Perl packages containing a single class, we use the lowercase class name,
11948 replace all occurrences of @code{::} by dashes and prepend the prefix
11950 So the class @code{XML::Parser} becomes @code{perl-xml-parser}.
11951 Modules containing several classes keep their lowercase upstream name and
11952 are also prepended by @code{perl-}. Such modules tend to have the word
11953 @code{perl} somewhere in their name, which gets dropped in favor of the
11954 prefix. For instance, @code{libwww-perl} becomes @code{perl-libwww}.
11957 @node Java Packages
11958 @subsection Java Packages
11960 Java programs standing for themselves are named as any other package,
11961 using the lowercase upstream name.
11963 To avoid confusion and naming clashes with other programming languages,
11964 it is desirable that the name of a package for a Java package is
11965 prefixed with @code{java-}. If a project already contains the word
11966 @code{java}, we drop this; for instance, the package @code{ngsjava} is
11967 packaged under the name @code{java-ngs}.
11969 For Java packages containing a single class or a small class hierarchy,
11970 we use the lowercase class name, replace all occurrences of @code{.} by
11971 dashes and prepend the prefix @code{java-}. So the class
11972 @code{apache.commons.cli} becomes package
11973 @code{java-apache-commons-cli}.
11979 For fonts that are in general not installed by a user for typesetting
11980 purposes, or that are distributed as part of a larger software package,
11981 we rely on the general packaging rules for software; for instance, this
11982 applies to the fonts delivered as part of the X.Org system or fonts that
11983 are part of TeX Live.
11985 To make it easier for a user to search for fonts, names for other packages
11986 containing only fonts are constructed as follows, independently of the
11987 upstream package name.
11989 The name of a package containing only one font family starts with
11990 @code{font-}; it is followed by the foundry name and a dash @code{-}
11991 if the foundry is known, and the font family name, in which spaces are
11992 replaced by dashes (and as usual, all upper case letters are transformed
11994 For example, the Gentium font family by SIL is packaged under the name
11995 @code{font-sil-gentium}.
11997 For a package containing several font families, the name of the collection
11998 is used in the place of the font family name.
11999 For instance, the Liberation fonts consist of three families,
12000 Liberation Sans, Liberation Serif and Liberation Mono.
12001 These could be packaged separately under the names
12002 @code{font-liberation-sans} and so on; but as they are distributed together
12003 under a common name, we prefer to package them together as
12004 @code{font-liberation}.
12006 In the case where several formats of the same font family or font collection
12007 are packaged separately, a short form of the format, prepended by a dash,
12008 is added to the package name. We use @code{-ttf} for TrueType fonts,
12009 @code{-otf} for OpenType fonts and @code{-type1} for PostScript Type 1
12014 @node Bootstrapping
12015 @section Bootstrapping
12017 @c Adapted from the ELS 2013 paper.
12019 @cindex bootstrapping
12021 Bootstrapping in our context refers to how the distribution gets built
12022 ``from nothing''. Remember that the build environment of a derivation
12023 contains nothing but its declared inputs (@pxref{Introduction}). So
12024 there's an obvious chicken-and-egg problem: how does the first package
12025 get built? How does the first compiler get compiled? Note that this is
12026 a question of interest only to the curious hacker, not to the regular
12027 user, so you can shamelessly skip this section if you consider yourself
12028 a ``regular user''.
12030 @cindex bootstrap binaries
12031 The GNU system is primarily made of C code, with libc at its core. The
12032 GNU build system itself assumes the availability of a Bourne shell and
12033 command-line tools provided by GNU Coreutils, Awk, Findutils, `sed', and
12034 `grep'. Furthermore, build programs---programs that run
12035 @code{./configure}, @code{make}, etc.---are written in Guile Scheme
12036 (@pxref{Derivations}). Consequently, to be able to build anything at
12037 all, from scratch, Guix relies on pre-built binaries of Guile, GCC,
12038 Binutils, libc, and the other packages mentioned above---the
12039 @dfn{bootstrap binaries}.
12041 These bootstrap binaries are ``taken for granted'', though we can also
12042 re-create them if needed (more on that later).
12044 @unnumberedsubsec Preparing to Use the Bootstrap Binaries
12046 @c As of Emacs 24.3, Info-mode displays the image, but since it's a
12047 @c large image, it's hard to scroll. Oh well.
12048 @image{images/bootstrap-graph,6in,,Dependency graph of the early bootstrap derivations}
12050 The figure above shows the very beginning of the dependency graph of the
12051 distribution, corresponding to the package definitions of the @code{(gnu
12052 packages bootstrap)} module. A similar figure can be generated with
12053 @command{guix graph} (@pxref{Invoking guix graph}), along the lines of:
12056 guix graph -t derivation \
12057 -e '(@@@@ (gnu packages bootstrap) %bootstrap-gcc)' \
12061 At this level of detail, things are
12062 slightly complex. First, Guile itself consists of an ELF executable,
12063 along with many source and compiled Scheme files that are dynamically
12064 loaded when it runs. This gets stored in the @file{guile-2.0.7.tar.xz}
12065 tarball shown in this graph. This tarball is part of Guix's ``source''
12066 distribution, and gets inserted into the store with @code{add-to-store}
12067 (@pxref{The Store}).
12069 But how do we write a derivation that unpacks this tarball and adds it
12070 to the store? To solve this problem, the @code{guile-bootstrap-2.0.drv}
12071 derivation---the first one that gets built---uses @code{bash} as its
12072 builder, which runs @code{build-bootstrap-guile.sh}, which in turn calls
12073 @code{tar} to unpack the tarball. Thus, @file{bash}, @file{tar},
12074 @file{xz}, and @file{mkdir} are statically-linked binaries, also part of
12075 the Guix source distribution, whose sole purpose is to allow the Guile
12076 tarball to be unpacked.
12078 Once @code{guile-bootstrap-2.0.drv} is built, we have a functioning
12079 Guile that can be used to run subsequent build programs. Its first task
12080 is to download tarballs containing the other pre-built binaries---this
12081 is what the @code{.tar.xz.drv} derivations do. Guix modules such as
12082 @code{ftp-client.scm} are used for this purpose. The
12083 @code{module-import.drv} derivations import those modules in a directory
12084 in the store, using the original layout. The
12085 @code{module-import-compiled.drv} derivations compile those modules, and
12086 write them in an output directory with the right layout. This
12087 corresponds to the @code{#:modules} argument of
12088 @code{build-expression->derivation} (@pxref{Derivations}).
12090 Finally, the various tarballs are unpacked by the
12091 derivations @code{gcc-bootstrap-0.drv}, @code{glibc-bootstrap-0.drv},
12092 etc., at which point we have a working C tool chain.
12095 @unnumberedsubsec Building the Build Tools
12097 Bootstrapping is complete when we have a full tool chain that does not
12098 depend on the pre-built bootstrap tools discussed above. This
12099 no-dependency requirement is verified by checking whether the files of
12100 the final tool chain contain references to the @file{/gnu/store}
12101 directories of the bootstrap inputs. The process that leads to this
12102 ``final'' tool chain is described by the package definitions found in
12103 the @code{(gnu packages commencement)} module.
12105 The @command{guix graph} command allows us to ``zoom out'' compared to
12106 the graph above, by looking at the level of package objects instead of
12107 individual derivations---remember that a package may translate to
12108 several derivations, typically one derivation to download its source,
12109 one to build the Guile modules it needs, and one to actually build the
12110 package from source. The command:
12113 guix graph -t bag \
12114 -e '(@@@@ (gnu packages commencement)
12115 glibc-final-with-bootstrap-bash)' | dot -Tps > t.ps
12119 produces the dependency graph leading to the ``final'' C
12120 library@footnote{You may notice the @code{glibc-intermediate} label,
12121 suggesting that it is not @emph{quite} final, but as a good
12122 approximation, we will consider it final.}, depicted below.
12124 @image{images/bootstrap-packages,6in,,Dependency graph of the early packages}
12126 @c See <http://lists.gnu.org/archive/html/gnu-system-discuss/2012-10/msg00000.html>.
12127 The first tool that gets built with the bootstrap binaries is
12128 GNU@tie{}Make---noted @code{make-boot0} above---which is a prerequisite
12129 for all the following packages. From there Findutils and Diffutils get
12132 Then come the first-stage Binutils and GCC, built as pseudo cross
12133 tools---i.e., with @code{--target} equal to @code{--host}. They are
12134 used to build libc. Thanks to this cross-build trick, this libc is
12135 guaranteed not to hold any reference to the initial tool chain.
12137 From there the final Binutils and GCC (not shown above) are built.
12139 from the final Binutils, and links programs against the just-built libc.
12140 This tool chain is used to build the other packages used by Guix and by
12141 the GNU Build System: Guile, Bash, Coreutils, etc.
12143 And voilà! At this point we have the complete set of build tools that
12144 the GNU Build System expects. These are in the @code{%final-inputs}
12145 variable of the @code{(gnu packages commencement)} module, and are
12146 implicitly used by any package that uses @code{gnu-build-system}
12147 (@pxref{Build Systems, @code{gnu-build-system}}).
12150 @unnumberedsubsec Building the Bootstrap Binaries
12152 Because the final tool chain does not depend on the bootstrap binaries,
12153 those rarely need to be updated. Nevertheless, it is useful to have an
12154 automated way to produce them, should an update occur, and this is what
12155 the @code{(gnu packages make-bootstrap)} module provides.
12157 The following command builds the tarballs containing the bootstrap
12158 binaries (Guile, Binutils, GCC, libc, and a tarball containing a mixture
12159 of Coreutils and other basic command-line tools):
12162 guix build bootstrap-tarballs
12165 The generated tarballs are those that should be referred to in the
12166 @code{(gnu packages bootstrap)} module mentioned at the beginning of
12169 Still here? Then perhaps by now you've started to wonder: when do we
12170 reach a fixed point? That is an interesting question! The answer is
12171 unknown, but if you would like to investigate further (and have
12172 significant computational and storage resources to do so), then let us
12176 @section Porting to a New Platform
12178 As discussed above, the GNU distribution is self-contained, and
12179 self-containment is achieved by relying on pre-built ``bootstrap
12180 binaries'' (@pxref{Bootstrapping}). These binaries are specific to an
12181 operating system kernel, CPU architecture, and application binary
12182 interface (ABI). Thus, to port the distribution to a platform that is
12183 not yet supported, one must build those bootstrap binaries, and update
12184 the @code{(gnu packages bootstrap)} module to use them on that platform.
12186 Fortunately, Guix can @emph{cross compile} those bootstrap binaries.
12187 When everything goes well, and assuming the GNU tool chain supports the
12188 target platform, this can be as simple as running a command like this
12192 guix build --target=armv5tel-linux-gnueabi bootstrap-tarballs
12195 For this to work, the @code{glibc-dynamic-linker} procedure in
12196 @code{(gnu packages bootstrap)} must be augmented to return the right
12197 file name for libc's dynamic linker on that platform; likewise,
12198 @code{system->linux-architecture} in @code{(gnu packages linux)} must be
12199 taught about the new platform.
12201 Once these are built, the @code{(gnu packages bootstrap)} module needs
12202 to be updated to refer to these binaries on the target platform. That
12203 is, the hashes and URLs of the bootstrap tarballs for the new platform
12204 must be added alongside those of the currently supported platforms. The
12205 bootstrap Guile tarball is treated specially: it is expected to be
12206 available locally, and @file{gnu/local.mk} has rules do download it for
12207 the supported architectures; a rule for the new platform must be added
12210 In practice, there may be some complications. First, it may be that the
12211 extended GNU triplet that specifies an ABI (like the @code{eabi} suffix
12212 above) is not recognized by all the GNU tools. Typically, glibc
12213 recognizes some of these, whereas GCC uses an extra @code{--with-abi}
12214 configure flag (see @code{gcc.scm} for examples of how to handle this).
12215 Second, some of the required packages could fail to build for that
12216 platform. Lastly, the generated binaries could be broken for some
12219 @c *********************************************************************
12220 @include contributing.texi
12222 @c *********************************************************************
12223 @node Acknowledgments
12224 @chapter Acknowledgments
12226 Guix is based on the @uref{http://nixos.org/nix/, Nix package manager},
12227 which was designed and
12228 implemented by Eelco Dolstra, with contributions from other people (see
12229 the @file{nix/AUTHORS} file in Guix.) Nix pioneered functional package
12230 management, and promoted unprecedented features, such as transactional
12231 package upgrades and rollbacks, per-user profiles, and referentially
12232 transparent build processes. Without this work, Guix would not exist.
12234 The Nix-based software distributions, Nixpkgs and NixOS, have also been
12235 an inspiration for Guix.
12237 GNU@tie{}Guix itself is a collective work with contributions from a
12238 number of people. See the @file{AUTHORS} file in Guix for more
12239 information on these fine people. The @file{THANKS} file lists people
12240 who have helped by reporting bugs, taking care of the infrastructure,
12241 providing artwork and themes, making suggestions, and more---thank you!
12244 @c *********************************************************************
12245 @node GNU Free Documentation License
12246 @appendix GNU Free Documentation License
12248 @include fdl-1.3.texi
12250 @c *********************************************************************
12251 @node Concept Index
12252 @unnumbered Concept Index
12255 @node Programming Index
12256 @unnumbered Programming Index
12257 @syncodeindex tp fn
12258 @syncodeindex vr fn
12263 @c Local Variables:
12264 @c ispell-local-dictionary: "american";