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 ng0
30 Permission is granted to copy, distribute and/or modify this document
31 under the terms of the GNU Free Documentation License, Version 1.3 or
32 any later version published by the Free Software Foundation; with no
33 Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A
34 copy of the license is included in the section entitled ``GNU Free
35 Documentation License''.
38 @dircategory System administration
40 * Guix: (guix). Manage installed software and system configuration.
41 * guix package: (guix)Invoking guix package. Installing, removing, and upgrading packages.
42 * guix build: (guix)Invoking guix build. Building packages.
43 * guix gc: (guix)Invoking guix gc. Reclaiming unused disk space.
44 * guix pull: (guix)Invoking guix pull. Update the list of available packages.
45 * guix system: (guix)Invoking guix system. Manage the operating system configuration.
48 @dircategory Software development
50 * guix environment: (guix)Invoking guix environment. Building development environments with Guix.
55 * Guix user interface: (guix)Emacs Interface. Package management from the comfort of Emacs.
60 @title GNU Guix Reference Manual
61 @subtitle Using the GNU Guix Functional Package Manager
62 @author The GNU Guix Developers
65 @vskip 0pt plus 1filll
66 Edition @value{EDITION} @*
74 @c *********************************************************************
78 This document describes GNU Guix version @value{VERSION}, a functional
79 package management tool written for the GNU system.
82 * Introduction:: What is Guix about?
83 * Installation:: Installing Guix.
84 * Package Management:: Package installation, upgrade, etc.
85 * Emacs Interface:: Using Guix from Emacs.
86 * Programming Interface:: Using Guix in Scheme.
87 * Utilities:: Package management commands.
88 * GNU Distribution:: Software for your friendly GNU system.
89 * Contributing:: Your help needed!
91 * Acknowledgments:: Thanks!
92 * GNU Free Documentation License:: The license of this manual.
93 * Concept Index:: Concepts.
94 * Programming Index:: Data types, functions, and variables.
97 --- The Detailed Node Listing ---
101 * Binary Installation:: Getting Guix running in no time!
102 * Requirements:: Software needed to build and run Guix.
103 * Running the Test Suite:: Testing Guix.
104 * Setting Up the Daemon:: Preparing the build daemon's environment.
105 * Invoking guix-daemon:: Running the build daemon.
106 * Application Setup:: Application-specific setup.
108 Setting Up the Daemon
110 * Build Environment Setup:: Preparing the isolated build environment.
111 * Daemon Offload Setup:: Offloading builds to remote machines.
115 * Features:: How Guix will make your life brighter.
116 * Invoking guix package:: Package installation, removal, etc.
117 * Substitutes:: Downloading pre-built binaries.
118 * Packages with Multiple Outputs:: Single source package, multiple outputs.
119 * Invoking guix gc:: Running the garbage collector.
120 * Invoking guix pull:: Fetching the latest Guix and distribution.
121 * Invoking guix archive:: Exporting and importing store files.
125 * Initial Setup: Emacs Initial Setup. Preparing @file{~/.emacs}.
126 * Package Management: Emacs Package Management. Managing packages and generations.
127 * Licenses: Emacs Licenses. Interface for licenses of Guix packages.
128 * Package Source Locations: Emacs Package Locations. Interface for package location files.
129 * Popup Interface: Emacs Popup Interface. Magit-like interface for guix commands.
130 * Prettify Mode: Emacs Prettify. Abbreviating @file{/gnu/store/@dots{}} file names.
131 * Build Log Mode: Emacs Build Log. Highlighting Guix build logs.
132 * Completions: Emacs Completions. Completing @command{guix} shell command.
133 * Development: Emacs Development. Tools for Guix developers.
134 * Hydra: Emacs Hydra. Interface for Guix build farm.
136 Programming Interface
138 * Defining Packages:: Defining new packages.
139 * Build Systems:: Specifying how packages are built.
140 * The Store:: Manipulating the package store.
141 * Derivations:: Low-level interface to package derivations.
142 * The Store Monad:: Purely functional interface to the store.
143 * G-Expressions:: Manipulating build expressions.
147 * package Reference:: The package data type.
148 * origin Reference:: The origin data type.
152 * Invoking guix build:: Building packages from the command line.
153 * Invoking guix edit:: Editing package definitions.
154 * Invoking guix download:: Downloading a file and printing its hash.
155 * Invoking guix hash:: Computing the cryptographic hash of a file.
156 * Invoking guix import:: Importing package definitions.
157 * Invoking guix refresh:: Updating package definitions.
158 * Invoking guix lint:: Finding errors in package definitions.
159 * Invoking guix size:: Profiling disk usage.
160 * Invoking guix graph:: Visualizing the graph of packages.
161 * Invoking guix environment:: Setting up development environments.
162 * Invoking guix publish:: Sharing substitutes.
163 * Invoking guix challenge:: Challenging substitute servers.
164 * Invoking guix container:: Process isolation.
166 Invoking @command{guix build}
168 * Common Build Options:: Build options for most commands.
169 * Package Transformation Options:: Creating variants of packages.
170 * Additional Build Options:: Options specific to 'guix build'.
174 * System Installation:: Installing the whole operating system.
175 * System Configuration:: Configuring the operating system.
176 * Installing Debugging Files:: Feeding the debugger.
177 * Security Updates:: Deploying security fixes quickly.
178 * Package Modules:: Packages from the programmer's viewpoint.
179 * Packaging Guidelines:: Growing the distribution.
180 * Bootstrapping:: GNU/Linux built from scratch.
181 * Porting:: Targeting another platform or kernel.
185 * Limitations:: What you can expect.
186 * Hardware Considerations:: Supported hardware.
187 * USB Stick Installation:: Preparing the installation medium.
188 * Preparing for Installation:: Networking, partitioning, etc.
189 * Proceeding with the Installation:: The real thing.
190 * Installing GuixSD in a VM:: GuixSD playground.
191 * Building the Installation Image:: How this comes to be.
195 * Using the Configuration System:: Customizing your GNU system.
196 * operating-system Reference:: Detail of operating-system declarations.
197 * File Systems:: Configuring file system mounts.
198 * Mapped Devices:: Block device extra processing.
199 * User Accounts:: Specifying user accounts.
200 * Locales:: Language and cultural convention settings.
201 * Services:: Specifying system services.
202 * Setuid Programs:: Programs running with root privileges.
203 * X.509 Certificates:: Authenticating HTTPS servers.
204 * Name Service Switch:: Configuring libc's name service switch.
205 * Initial RAM Disk:: Linux-Libre bootstrapping.
206 * GRUB Configuration:: Configuring the boot loader.
207 * Invoking guix system:: Instantiating a system configuration.
208 * Running GuixSD in a VM:: How to run GuixSD in a virtual machine.
209 * Defining Services:: Adding new service definitions.
213 * Base Services:: Essential system services.
214 * Scheduled Job Execution:: The mcron service.
215 * Networking Services:: Network setup, SSH daemon, etc.
216 * X Window:: Graphical display.
217 * Desktop Services:: D-Bus and desktop services.
218 * Database Services:: SQL databases.
219 * Mail Services:: IMAP, POP3, SMTP, and all that.
220 * Web Services:: Web servers.
221 * Various Services:: Other services.
225 * Service Composition:: The model for composing services.
226 * Service Types and Services:: Types and services.
227 * Service Reference:: API reference.
228 * Shepherd Services:: A particular type of service.
232 * Software Freedom:: What may go into the distribution.
233 * Package Naming:: What's in a name?
234 * Version Numbers:: When the name is not enough.
235 * Synopses and Descriptions:: Helping users find the right package.
236 * Python Modules:: Taming the snake.
237 * Perl Modules:: Little pearls.
238 * Java Packages:: Coffee break.
239 * Fonts:: Fond of fonts.
243 * Building from Git:: The latest and greatest.
244 * Running Guix Before It Is Installed:: Hacker tricks.
245 * The Perfect Setup:: The right tools.
246 * Coding Style:: Hygiene of the contributor.
247 * Submitting Patches:: Share your work.
251 * Programming Paradigm:: How to compose your elements.
252 * Modules:: Where to store your code?
253 * Data Types and Pattern Matching:: Implementing data structures.
254 * Formatting Code:: Writing conventions.
259 @c *********************************************************************
261 @chapter Introduction
264 GNU Guix@footnote{``Guix'' is pronounced like ``geeks'', or ``ɡiːks''
265 using the international phonetic alphabet (IPA).} is a package
266 management tool for the GNU system. Guix makes it easy for unprivileged
267 users to install, upgrade, or remove packages, to roll back to a
268 previous package set, to build packages from source, and generally
269 assists with the creation and maintenance of software environments.
271 @cindex user interfaces
272 Guix provides a command-line package management interface
273 (@pxref{Invoking guix package}), a set of command-line utilities
274 (@pxref{Utilities}), a visual user interface in Emacs (@pxref{Emacs
275 Interface}), as well as Scheme programming interfaces
276 (@pxref{Programming Interface}).
278 Its @dfn{build daemon} is responsible for building packages on behalf of
279 users (@pxref{Setting Up the Daemon}) and for downloading pre-built
280 binaries from authorized sources (@pxref{Substitutes}).
282 @cindex extensibility of the distribution
283 @cindex customization of packages
284 Guix includes package definitions for many GNU and non-GNU packages, all
285 of which @uref{https://www.gnu.org/philosophy/free-sw.html, respect the
286 user's computing freedom}. It is @emph{extensible}: users can write
287 their own package definitions (@pxref{Defining Packages}) and make them
288 available as independent package modules (@pxref{Package Modules}). It
289 is also @emph{customizable}: users can @emph{derive} specialized package
290 definitions from existing ones, including from the command line
291 (@pxref{Package Transformation Options}).
293 @cindex Guix System Distribution
295 You can install GNU@tie{}Guix on top of an existing GNU/Linux system
296 where it complements the available tools without interference
297 (@pxref{Installation}), or you can use it as part of the standalone
298 @dfn{Guix System Distribution} or GuixSD (@pxref{GNU Distribution}).
299 With GNU@tie{}GuixSD, you @emph{declare} all aspects of the operating
300 system configuration and Guix takes care of instantiating the
301 configuration in a transactional, reproducible, and stateless fashion
302 (@pxref{System Configuration}).
304 @cindex functional package management
305 Under the hood, Guix implements the @dfn{functional package management}
306 discipline pioneered by Nix (@pxref{Acknowledgments}).
307 In Guix, the package build and installation process is seen
308 as a @emph{function}, in the mathematical sense. That function takes inputs,
309 such as build scripts, a compiler, and libraries, and
310 returns an installed package. As a pure function, its result depends
311 solely on its inputs---for instance, it cannot refer to software or
312 scripts that were not explicitly passed as inputs. A build function
313 always produces the same result when passed a given set of inputs. It
314 cannot alter the environment of the running system in
315 any way; for instance, it cannot create, modify, or delete files outside
316 of its build and installation directories. This is achieved by running
317 build processes in isolated environments (or @dfn{containers}), where only their
318 explicit inputs are visible.
321 The result of package build functions is @dfn{cached} in the file
322 system, in a special directory called @dfn{the store} (@pxref{The
323 Store}). Each package is installed in a directory of its own in the
324 store---by default under @file{/gnu/store}. The directory name contains
325 a hash of all the inputs used to build that package; thus, changing an
326 input yields a different directory name.
328 This approach is the foundation for the salient features of Guix: support
329 for transactional package upgrade and rollback, per-user installation, and
330 garbage collection of packages (@pxref{Features}).
333 @c *********************************************************************
335 @chapter Installation
337 GNU Guix is available for download from its website at
338 @url{http://www.gnu.org/software/guix/}. This section describes the
339 software requirements of Guix, as well as how to install it and get
342 Note that this section is concerned with the installation of the package
343 manager, which can be done on top of a running GNU/Linux system. If,
344 instead, you want to install the complete GNU operating system,
345 @pxref{System Installation}.
347 @cindex foreign distro
348 When installed on a running GNU/Linux system---thereafter called a
349 @dfn{foreign distro}---GNU@tie{}Guix complements the available tools
350 without interference. Its data lives exclusively in two directories,
351 usually @file{/gnu/store} and @file{/var/guix}; other files on your
352 system, such as @file{/etc}, are left untouched.
355 * Binary Installation:: Getting Guix running in no time!
356 * Requirements:: Software needed to build and run Guix.
357 * Running the Test Suite:: Testing Guix.
358 * Setting Up the Daemon:: Preparing the build daemon's environment.
359 * Invoking guix-daemon:: Running the build daemon.
360 * Application Setup:: Application-specific setup.
363 @node Binary Installation
364 @section Binary Installation
366 This section describes how to install Guix on an arbitrary system from a
367 self-contained tarball providing binaries for Guix and for all its
368 dependencies. This is often quicker than installing from source, which
369 is described in the next sections. The only requirement is to have
372 Installing goes along these lines:
376 Download the binary tarball from
377 @indicateurl{ftp://alpha.gnu.org/gnu/guix/guix-binary-@value{VERSION}.@var{system}.tar.xz},
378 where @var{system} is @code{x86_64-linux} for an @code{x86_64} machine
379 already running the kernel Linux, and so on.
381 @c The following is somewhat duplicated in ``System Installation''.
382 Make sure to download the associated @file{.sig} file and to verify the
383 authenticity of the tarball against it, along these lines:
386 $ wget ftp://alpha.gnu.org/gnu/guix/guix-binary-@value{VERSION}.@var{system}.tar.xz.sig
387 $ gpg --verify guix-binary-@value{VERSION}.@var{system}.tar.xz.sig
390 If that command fails because you do not have the required public key,
391 then run this command to import it:
394 $ gpg --keyserver pgp.mit.edu --recv-keys @value{OPENPGP-SIGNING-KEY-ID}
398 and rerun the @code{gpg --verify} command.
399 @c end authentication part
406 # tar --warning=no-timestamp -xf \
407 guix-binary-@value{VERSION}.@var{system}.tar.xz
408 # mv var/guix /var/ && mv gnu /
411 This creates @file{/gnu/store} (@pxref{The Store}) and @file{/var/guix}.
412 The latter contains a ready-to-use profile for @code{root} (see next
415 Do @emph{not} unpack the tarball on a working Guix system since that
416 would overwrite its own essential files.
418 The @code{--warning=no-timestamp} option makes sure GNU@tie{}tar does
419 not emit warnings about ``implausibly old time stamps'' (such
420 warnings were triggered by GNU@tie{}tar 1.26 and older; recent
422 They stem from the fact that all the
423 files in the archive have their modification time set to zero (which
424 means January 1st, 1970.) This is done on purpose to make sure the
425 archive content is independent of its creation time, thus making it
429 Make @code{root}'s profile available under @file{~/.guix-profile}:
432 # ln -sf /var/guix/profiles/per-user/root/guix-profile \
437 Create the group and user accounts for build users as explained below
438 (@pxref{Build Environment Setup}).
441 Run the daemon, and set it to automatically start on boot.
443 If your host distro uses the systemd init system, this can be achieved
447 # cp ~root/.guix-profile/lib/systemd/system/guix-daemon.service \
449 # systemctl start guix-daemon && systemctl enable guix-daemon
452 If your host distro uses the Upstart init system:
455 # cp ~root/.guix-profile/lib/upstart/system/guix-daemon.conf /etc/init/
459 Otherwise, you can still start the daemon manually with:
462 # ~root/.guix-profile/bin/guix-daemon --build-users-group=guixbuild
466 Make the @command{guix} command available to other users on the machine,
470 # mkdir -p /usr/local/bin
472 # ln -s /var/guix/profiles/per-user/root/guix-profile/bin/guix
475 It is also a good idea to make the Info version of this manual available
479 # mkdir -p /usr/local/share/info
480 # cd /usr/local/share/info
481 # for i in /var/guix/profiles/per-user/root/guix-profile/share/info/* ;
485 That way, assuming @file{/usr/local/share/info} is in the search path,
486 running @command{info guix} will open this manual (@pxref{Other Info
487 Directories,,, texinfo, GNU Texinfo}, for more details on changing the
491 To use substitutes from @code{hydra.gnu.org} or one of its mirrors
492 (@pxref{Substitutes}), authorize them:
495 # guix archive --authorize < ~root/.guix-profile/share/guix/hydra.gnu.org.pub
499 This completes root-level install of Guix. Each user will need to
500 perform additional steps to make their Guix environment ready for use,
501 @pxref{Application Setup}.
503 You can confirm that Guix is working by installing a sample package into
507 # guix package -i hello
510 The @code{guix} package must remain available in @code{root}'s profile,
511 or it would become subject to garbage collection---in which case you
512 would find yourself badly handicapped by the lack of the @command{guix}
513 command. In other words, do not remove @code{guix} by running
514 @code{guix package -r guix}.
516 The binary installation tarball can be (re)produced and verified simply
517 by running the following command in the Guix source tree:
520 make guix-binary.@var{system}.tar.xz
525 @section Requirements
527 This section lists requirements when building Guix from source. The
528 build procedure for Guix is the same as for other GNU software, and is
529 not covered here. Please see the files @file{README} and @file{INSTALL}
530 in the Guix source tree for additional details.
532 GNU Guix depends on the following packages:
535 @item @url{http://gnu.org/software/guile/, GNU Guile}, version 2.0.7 or later;
536 @item @url{http://gnupg.org/, GNU libgcrypt};
537 @item @url{http://www.gnu.org/software/make/, GNU Make}.
540 The following dependencies are optional:
544 Installing @uref{http://gnutls.org/, GnuTLS-Guile} will allow you to
545 access @code{https} URLs for substitutes, which is highly recommended
546 (@pxref{Substitutes}). It also allows you to access HTTPS URLs with the
547 @command{guix download} command (@pxref{Invoking guix download}), the
548 @command{guix import pypi} command, and the @command{guix import cpan}
549 command. @xref{Guile Preparations, how to install the GnuTLS bindings
550 for Guile,, gnutls-guile, GnuTLS-Guile}.
554 @url{http://savannah.nongnu.org/projects/guile-json/, Guile-JSON} will
555 allow you to use the @command{guix import pypi} command (@pxref{Invoking
556 guix import}). It is of
557 interest primarily for developers and not for casual users.
560 When @url{http://zlib.net, zlib} is available, @command{guix publish}
561 can compress build byproducts (@pxref{Invoking guix publish}).
564 Unless @code{--disable-daemon} was passed to @command{configure}, the
565 following packages are also needed:
568 @item @url{http://sqlite.org, SQLite 3};
569 @item @url{http://www.bzip.org, libbz2};
570 @item @url{http://gcc.gnu.org, GCC's g++}, with support for the
574 When configuring Guix on a system that already has a Guix installation,
575 be sure to specify the same state directory as the existing installation
576 using the @code{--localstatedir} option of the @command{configure}
577 script (@pxref{Directory Variables, @code{localstatedir},, standards,
578 GNU Coding Standards}). The @command{configure} script protects against
579 unintended misconfiguration of @var{localstatedir} so you do not
580 inadvertently corrupt your store (@pxref{The Store}).
582 When a working installation of @url{http://nixos.org/nix/, the Nix package
583 manager} is available, you
584 can instead configure Guix with @code{--disable-daemon}. In that case,
585 Nix replaces the three dependencies above.
587 Guix is compatible with Nix, so it is possible to share the same store
588 between both. To do so, you must pass @command{configure} not only the
589 same @code{--with-store-dir} value, but also the same
590 @code{--localstatedir} value. The latter is essential because it
591 specifies where the database that stores metadata about the store is
592 located, among other things. The default values for Nix are
593 @code{--with-store-dir=/nix/store} and @code{--localstatedir=/nix/var}.
594 Note that @code{--disable-daemon} is not required if
595 your goal is to share the store with Nix.
597 @node Running the Test Suite
598 @section Running the Test Suite
600 After a successful @command{configure} and @code{make} run, it is a good
601 idea to run the test suite. It can help catch issues with the setup or
602 environment, or bugs in Guix itself---and really, reporting test
603 failures is a good way to help improve the software. To run the test
610 Test cases can run in parallel: you can use the @code{-j} option of
611 GNU@tie{}make to speed things up. The first run may take a few minutes
612 on a recent machine; subsequent runs will be faster because the store
613 that is created for test purposes will already have various things in
616 It is also possible to run a subset of the tests by defining the
617 @code{TESTS} makefile variable as in this example:
620 make check TESTS="tests/store.scm tests/cpio.scm"
623 By default, tests results are displayed at a file level. In order to
624 see the details of every individual test cases, it is possible to define
625 the @code{SCM_LOG_DRIVER_FLAGS} makefile variable as in this example:
628 make check TESTS="tests/base64.scm" SCM_LOG_DRIVER_FLAGS="--brief=no"
631 Upon failure, please email @email{bug-guix@@gnu.org} and attach the
632 @file{test-suite.log} file. Please specify the Guix version being used
633 as well as version numbers of the dependencies (@pxref{Requirements}) in
636 Guix also comes with a whole-system test suite that tests complete
637 GuixSD operating system instances. It can only run on systems where
638 Guix is already installed, using:
645 or, again, by defining @code{TESTS} to select a subset of tests to run:
648 make check-system TESTS="basic mcron"
651 These system tests are defined in the @code{(gnu tests @dots{})}
652 modules. They work by running the operating systems under test with
653 lightweight instrumentation in a virtual machine (VM). They can be
654 computationally intensive or rather cheap, depending on whether
655 substitutes are available for their dependencies (@pxref{Substitutes}).
656 Some of them require a lot of storage space to hold VM images.
658 Again in case of test failures, please send @email{bug-guix@@gnu.org}
661 @node Setting Up the Daemon
662 @section Setting Up the Daemon
665 Operations such as building a package or running the garbage collector
666 are all performed by a specialized process, the @dfn{build daemon}, on
667 behalf of clients. Only the daemon may access the store and its
668 associated database. Thus, any operation that manipulates the store
669 goes through the daemon. For instance, command-line tools such as
670 @command{guix package} and @command{guix build} communicate with the
671 daemon (@i{via} remote procedure calls) to instruct it what to do.
673 The following sections explain how to prepare the build daemon's
674 environment. See also @ref{Substitutes}, for information on how to allow
675 the daemon to download pre-built binaries.
678 * Build Environment Setup:: Preparing the isolated build environment.
679 * Daemon Offload Setup:: Offloading builds to remote machines.
682 @node Build Environment Setup
683 @subsection Build Environment Setup
685 In a standard multi-user setup, Guix and its daemon---the
686 @command{guix-daemon} program---are installed by the system
687 administrator; @file{/gnu/store} is owned by @code{root} and
688 @command{guix-daemon} runs as @code{root}. Unprivileged users may use
689 Guix tools to build packages or otherwise access the store, and the
690 daemon will do it on their behalf, ensuring that the store is kept in a
691 consistent state, and allowing built packages to be shared among users.
694 When @command{guix-daemon} runs as @code{root}, you may not want package
695 build processes themselves to run as @code{root} too, for obvious
696 security reasons. To avoid that, a special pool of @dfn{build users}
697 should be created for use by build processes started by the daemon.
698 These build users need not have a shell and a home directory: they will
699 just be used when the daemon drops @code{root} privileges in build
700 processes. Having several such users allows the daemon to launch
701 distinct build processes under separate UIDs, which guarantees that they
702 do not interfere with each other---an essential feature since builds are
703 regarded as pure functions (@pxref{Introduction}).
705 On a GNU/Linux system, a build user pool may be created like this (using
706 Bash syntax and the @code{shadow} commands):
708 @c See http://lists.gnu.org/archive/html/bug-guix/2013-01/msg00239.html
709 @c for why `-G' is needed.
711 # groupadd --system guixbuild
712 # for i in `seq -w 1 10`;
714 useradd -g guixbuild -G guixbuild \
715 -d /var/empty -s `which nologin` \
716 -c "Guix build user $i" --system \
722 The number of build users determines how many build jobs may run in
723 parallel, as specified by the @option{--max-jobs} option
724 (@pxref{Invoking guix-daemon, @option{--max-jobs}}). To use
725 @command{guix system vm} and related commands, you may need to add the
726 build users to the @code{kvm} group so they can access @file{/dev/kvm},
727 using @code{-G guixbuild,kvm} instead of @code{-G guixbuild}
728 (@pxref{Invoking guix system}).
730 The @code{guix-daemon} program may then be run as @code{root} with the
731 following command@footnote{If your machine uses the systemd init system,
732 dropping the @file{@var{prefix}/lib/systemd/system/guix-daemon.service}
733 file in @file{/etc/systemd/system} will ensure that
734 @command{guix-daemon} is automatically started. Similarly, if your
735 machine uses the Upstart init system, drop the
736 @file{@var{prefix}/lib/upstart/system/guix-daemon.conf}
737 file in @file{/etc/init}.}:
740 # guix-daemon --build-users-group=guixbuild
745 This way, the daemon starts build processes in a chroot, under one of
746 the @code{guixbuilder} users. On GNU/Linux, by default, the chroot
747 environment contains nothing but:
749 @c Keep this list in sync with libstore/build.cc! -----------------------
752 a minimal @code{/dev} directory, created mostly independently from the
753 host @code{/dev}@footnote{``Mostly'', because while the set of files
754 that appear in the chroot's @code{/dev} is fixed, most of these files
755 can only be created if the host has them.};
758 the @code{/proc} directory; it only shows the processes of the container
759 since a separate PID name space is used;
762 @file{/etc/passwd} with an entry for the current user and an entry for
766 @file{/etc/group} with an entry for the user's group;
769 @file{/etc/hosts} with an entry that maps @code{localhost} to
773 a writable @file{/tmp} directory.
776 You can influence the directory where the daemon stores build trees
777 @i{via} the @code{TMPDIR} environment variable. However, the build tree
778 within the chroot is always called @file{/tmp/guix-build-@var{name}.drv-0},
779 where @var{name} is the derivation name---e.g., @code{coreutils-8.24}.
780 This way, the value of @code{TMPDIR} does not leak inside build
781 environments, which avoids discrepancies in cases where build processes
782 capture the name of their build tree.
785 The daemon also honors the @code{http_proxy} environment variable for
786 HTTP downloads it performs, be it for fixed-output derivations
787 (@pxref{Derivations}) or for substitutes (@pxref{Substitutes}).
789 If you are installing Guix as an unprivileged user, it is still possible
790 to run @command{guix-daemon} provided you pass @code{--disable-chroot}.
791 However, build processes will not be isolated from one another, and not
792 from the rest of the system. Thus, build processes may interfere with
793 each other, and may access programs, libraries, and other files
794 available on the system---making it much harder to view them as
795 @emph{pure} functions.
798 @node Daemon Offload Setup
799 @subsection Using the Offload Facility
803 When desired, the build daemon can @dfn{offload}
804 derivation builds to other machines
805 running Guix, using the @code{offload} @dfn{build hook}. When that
806 feature is enabled, a list of user-specified build machines is read from
807 @file{/etc/guix/machines.scm}; every time a build is requested, for
808 instance via @code{guix build}, the daemon attempts to offload it to one
809 of the machines that satisfy the constraints of the derivation, in
810 particular its system type---e.g., @file{x86_64-linux}. Missing
811 prerequisites for the build are copied over SSH to the target machine,
812 which then proceeds with the build; upon success the output(s) of the
813 build are copied back to the initial machine.
815 The @file{/etc/guix/machines.scm} file typically looks like this:
819 (name "eightysix.example.org")
820 (system "x86_64-linux")
822 (speed 2.)) ; incredibly fast!
825 (name "meeps.example.org")
826 (system "mips64el-linux")
829 (string-append (getenv "HOME")
830 "/.lsh/identity-for-guix"))))
834 In the example above we specify a list of two build machines, one for
835 the @code{x86_64} architecture and one for the @code{mips64el}
838 In fact, this file is---not surprisingly!---a Scheme file that is
839 evaluated when the @code{offload} hook is started. Its return value
840 must be a list of @code{build-machine} objects. While this example
841 shows a fixed list of build machines, one could imagine, say, using
842 DNS-SD to return a list of potential build machines discovered in the
843 local network (@pxref{Introduction, Guile-Avahi,, guile-avahi, Using
844 Avahi in Guile Scheme Programs}). The @code{build-machine} data type is
847 @deftp {Data Type} build-machine
848 This data type represents build machines to which the daemon may offload
849 builds. The important fields are:
854 The host name of the remote machine.
857 The system type of the remote machine---e.g., @code{"x86_64-linux"}.
860 The user account to use when connecting to the remote machine over SSH.
861 Note that the SSH key pair must @emph{not} be passphrase-protected, to
862 allow non-interactive logins.
866 A number of optional fields may be specified:
871 Port number of SSH server on the machine (default: 22).
874 The SSH private key file to use when connecting to the machine.
876 Currently offloading uses GNU@tie{}lsh as its SSH client
877 (@pxref{Invoking lsh,,, GNU lsh Manual}). Thus, the key file here must
878 be an lsh key file. This may change in the future, though.
880 @item parallel-builds
881 The number of builds that may run in parallel on the machine (1 by
885 A ``relative speed factor''. The offload scheduler will tend to prefer
886 machines with a higher speed factor.
889 A list of strings denoting specific features supported by the machine.
890 An example is @code{"kvm"} for machines that have the KVM Linux modules
891 and corresponding hardware support. Derivations can request features by
892 name, and they will be scheduled on matching build machines.
897 The @code{guix} command must be in the search path on the build
898 machines, since offloading works by invoking the @code{guix archive} and
899 @code{guix build} commands. In addition, the Guix modules must be in
900 @code{$GUILE_LOAD_PATH} on the build machine---you can check whether
901 this is the case by running:
904 lsh build-machine guile -c "'(use-modules (guix config))'"
907 There is one last thing to do once @file{machines.scm} is in place. As
908 explained above, when offloading, files are transferred back and forth
909 between the machine stores. For this to work, you first need to
910 generate a key pair on each machine to allow the daemon to export signed
911 archives of files from the store (@pxref{Invoking guix archive}):
914 # guix archive --generate-key
918 Each build machine must authorize the key of the master machine so that
919 it accepts store items it receives from the master:
922 # guix archive --authorize < master-public-key.txt
926 Likewise, the master machine must authorize the key of each build machine.
928 All the fuss with keys is here to express pairwise mutual trust
929 relations between the master and the build machines. Concretely, when
930 the master receives files from a build machine (and @i{vice versa}), its
931 build daemon can make sure they are genuine, have not been tampered
932 with, and that they are signed by an authorized key.
935 @node Invoking guix-daemon
936 @section Invoking @command{guix-daemon}
938 The @command{guix-daemon} program implements all the functionality to
939 access the store. This includes launching build processes, running the
940 garbage collector, querying the availability of a build result, etc. It
941 is normally run as @code{root} like this:
944 # guix-daemon --build-users-group=guixbuild
948 For details on how to set it up, @pxref{Setting Up the Daemon}.
951 @cindex container, build environment
952 @cindex build environment
953 @cindex reproducible builds
954 By default, @command{guix-daemon} launches build processes under
955 different UIDs, taken from the build group specified with
956 @code{--build-users-group}. In addition, each build process is run in a
957 chroot environment that only contains the subset of the store that the
958 build process depends on, as specified by its derivation
959 (@pxref{Programming Interface, derivation}), plus a set of specific
960 system directories. By default, the latter contains @file{/dev} and
961 @file{/dev/pts}. Furthermore, on GNU/Linux, the build environment is a
962 @dfn{container}: in addition to having its own file system tree, it has
963 a separate mount name space, its own PID name space, network name space,
964 etc. This helps achieve reproducible builds (@pxref{Features}).
966 When the daemon performs a build on behalf of the user, it creates a
967 build directory under @file{/tmp} or under the directory specified by
968 its @code{TMPDIR} environment variable; this directory is shared with
969 the container for the duration of the build. Be aware that using a
970 directory other than @file{/tmp} can affect build results---for example,
971 with a longer directory name, a build process that uses Unix-domain
972 sockets might hit the name length limitation for @code{sun_path}, which
973 it would otherwise not hit.
975 The build directory is automatically deleted upon completion, unless the
976 build failed and the client specified @option{--keep-failed}
977 (@pxref{Invoking guix build, @option{--keep-failed}}).
979 The following command-line options are supported:
982 @item --build-users-group=@var{group}
983 Take users from @var{group} to run build processes (@pxref{Setting Up
984 the Daemon, build users}).
986 @item --no-substitutes
988 Do not use substitutes for build products. That is, always build things
989 locally instead of allowing downloads of pre-built binaries
990 (@pxref{Substitutes}).
992 By default substitutes are used, unless the client---such as the
993 @command{guix package} command---is explicitly invoked with
994 @code{--no-substitutes}.
996 When the daemon runs with @code{--no-substitutes}, clients can still
997 explicitly enable substitution @i{via} the @code{set-build-options}
998 remote procedure call (@pxref{The Store}).
1000 @item --substitute-urls=@var{urls}
1001 @anchor{daemon-substitute-urls}
1002 Consider @var{urls} the default whitespace-separated list of substitute
1003 source URLs. When this option is omitted,
1004 @indicateurl{https://mirror.hydra.gnu.org https://hydra.gnu.org} is used
1005 (@code{mirror.hydra.gnu.org} is a mirror of @code{hydra.gnu.org}).
1007 This means that substitutes may be downloaded from @var{urls}, as long
1008 as they are signed by a trusted signature (@pxref{Substitutes}).
1011 @item --no-build-hook
1012 Do not use the @dfn{build hook}.
1014 The build hook is a helper program that the daemon can start and to
1015 which it submits build requests. This mechanism is used to offload
1016 builds to other machines (@pxref{Daemon Offload Setup}).
1018 @item --cache-failures
1019 Cache build failures. By default, only successful builds are cached.
1021 When this option is used, @command{guix gc --list-failures} can be used
1022 to query the set of store items marked as failed; @command{guix gc
1023 --clear-failures} removes store items from the set of cached failures.
1024 @xref{Invoking guix gc}.
1026 @item --cores=@var{n}
1028 Use @var{n} CPU cores to build each derivation; @code{0} means as many
1031 The default value is @code{0}, but it may be overridden by clients, such
1032 as the @code{--cores} option of @command{guix build} (@pxref{Invoking
1035 The effect is to define the @code{NIX_BUILD_CORES} environment variable
1036 in the build process, which can then use it to exploit internal
1037 parallelism---for instance, by running @code{make -j$NIX_BUILD_CORES}.
1039 @item --max-jobs=@var{n}
1041 Allow at most @var{n} build jobs in parallel. The default value is
1042 @code{1}. Setting it to @code{0} means that no builds will be performed
1043 locally; instead, the daemon will offload builds (@pxref{Daemon Offload
1044 Setup}), or simply fail.
1046 @item --rounds=@var{N}
1047 Build each derivation @var{n} times in a row, and raise an error if
1048 consecutive build results are not bit-for-bit identical. Note that this
1049 setting can be overridden by clients such as @command{guix build}
1050 (@pxref{Invoking guix build}).
1052 When used in conjunction with @option{--keep-failed}, the differing
1053 output is kept in the store, under @file{/gnu/store/@dots{}-check}.
1054 This makes it easy to look for differences between the two results.
1057 Produce debugging output.
1059 This is useful to debug daemon start-up issues, but then it may be
1060 overridden by clients, for example the @code{--verbosity} option of
1061 @command{guix build} (@pxref{Invoking guix build}).
1063 @item --chroot-directory=@var{dir}
1064 Add @var{dir} to the build chroot.
1066 Doing this may change the result of build processes---for instance if
1067 they use optional dependencies found in @var{dir} when it is available,
1068 and not otherwise. For that reason, it is not recommended to do so.
1069 Instead, make sure that each derivation declares all the inputs that it
1072 @item --disable-chroot
1073 Disable chroot builds.
1075 Using this option is not recommended since, again, it would allow build
1076 processes to gain access to undeclared dependencies. It is necessary,
1077 though, when @command{guix-daemon} is running under an unprivileged user
1080 @item --disable-log-compression
1081 Disable compression of the build logs.
1083 Unless @code{--lose-logs} is used, all the build logs are kept in the
1084 @var{localstatedir}. To save space, the daemon automatically compresses
1085 them with bzip2 by default. This option disables that.
1087 @item --disable-deduplication
1088 @cindex deduplication
1089 Disable automatic file ``deduplication'' in the store.
1091 By default, files added to the store are automatically ``deduplicated'':
1092 if a newly added file is identical to another one found in the store,
1093 the daemon makes the new file a hard link to the other file. This can
1094 noticeably reduce disk usage, at the expense of slightly increased
1095 input/output load at the end of a build process. This option disables
1098 @item --gc-keep-outputs[=yes|no]
1099 Tell whether the garbage collector (GC) must keep outputs of live
1102 When set to ``yes'', the GC will keep the outputs of any live derivation
1103 available in the store---the @code{.drv} files. The default is ``no'',
1104 meaning that derivation outputs are kept only if they are GC roots.
1106 @item --gc-keep-derivations[=yes|no]
1107 Tell whether the garbage collector (GC) must keep derivations
1108 corresponding to live outputs.
1110 When set to ``yes'', as is the case by default, the GC keeps
1111 derivations---i.e., @code{.drv} files---as long as at least one of their
1112 outputs is live. This allows users to keep track of the origins of
1113 items in their store. Setting it to ``no'' saves a bit of disk space.
1115 Note that when both @code{--gc-keep-derivations} and
1116 @code{--gc-keep-outputs} are used, the effect is to keep all the build
1117 prerequisites (the sources, compiler, libraries, and other build-time
1118 tools) of live objects in the store, regardless of whether these
1119 prerequisites are live. This is convenient for developers since it
1120 saves rebuilds or downloads.
1122 @item --impersonate-linux-2.6
1123 On Linux-based systems, impersonate Linux 2.6. This means that the
1124 kernel's @code{uname} system call will report 2.6 as the release number.
1126 This might be helpful to build programs that (usually wrongfully) depend
1127 on the kernel version number.
1130 Do not keep build logs. By default they are kept under
1131 @code{@var{localstatedir}/guix/log}.
1133 @item --system=@var{system}
1134 Assume @var{system} as the current system type. By default it is the
1135 architecture/kernel pair found at configure time, such as
1136 @code{x86_64-linux}.
1138 @item --listen=@var{socket}
1139 Listen for connections on @var{socket}, the file name of a Unix-domain
1140 socket. The default socket is
1141 @file{@var{localstatedir}/daemon-socket/socket}. This option is only
1142 useful in exceptional circumstances, such as if you need to run several
1143 daemons on the same machine.
1147 @node Application Setup
1148 @section Application Setup
1150 @cindex foreign distro
1151 When using Guix on top of GNU/Linux distribution other than GuixSD---a
1152 so-called @dfn{foreign distro}---a few additional steps are needed to
1153 get everything in place. Here are some of them.
1157 @anchor{locales-and-locpath}
1158 @cindex locales, when not on GuixSD
1160 @vindex GUIX_LOCPATH
1161 Packages installed @i{via} Guix will not use the locale data of the
1162 host system. Instead, you must first install one of the locale packages
1163 available with Guix and then define the @code{GUIX_LOCPATH} environment
1167 $ guix package -i glibc-locales
1168 $ export GUIX_LOCPATH=$HOME/.guix-profile/lib/locale
1171 Note that the @code{glibc-locales} package contains data for all the
1172 locales supported by the GNU@tie{}libc and weighs in at around
1173 110@tie{}MiB. Alternatively, the @code{glibc-utf8-locales} is smaller but
1174 limited to a few UTF-8 locales.
1176 The @code{GUIX_LOCPATH} variable plays a role similar to @code{LOCPATH}
1177 (@pxref{Locale Names, @code{LOCPATH},, libc, The GNU C Library Reference
1178 Manual}). There are two important differences though:
1182 @code{GUIX_LOCPATH} is honored only by the libc in Guix, and not by the libc
1183 provided by foreign distros. Thus, using @code{GUIX_LOCPATH} allows you
1184 to make sure the programs of the foreign distro will not end up loading
1185 incompatible locale data.
1188 libc suffixes each entry of @code{GUIX_LOCPATH} with @code{/X.Y}, where
1189 @code{X.Y} is the libc version---e.g., @code{2.22}. This means that,
1190 should your Guix profile contain a mixture of programs linked against
1191 different libc version, each libc version will only try to load locale
1192 data in the right format.
1195 This is important because the locale data format used by different libc
1196 versions may be incompatible.
1198 @subsection X11 Fonts
1200 The majority of graphical applications use Fontconfig to locate and
1201 load fonts and perform X11-client-side rendering. The @code{fontconfig}
1202 package in Guix looks for fonts in @file{$HOME/.guix-profile}
1203 by default. Thus, to allow graphical applications installed with Guix
1204 to display fonts, you have to install fonts with Guix as well.
1205 Essential font packages include @code{gs-fonts}, @code{font-dejavu}, and
1206 @code{font-gnu-freefont-ttf}.
1208 To display text written in Chinese languages, Japanese, or Korean in
1209 graphical applications, consider installing
1210 @code{font-adobe-source-han-sans} or @code{font-wqy-zenhei}. The former
1211 has multiple outputs, one per language family (@pxref{Packages with
1212 Multiple Outputs}). For instance, the following command installs fonts
1213 for Chinese languages:
1216 guix package -i font-adobe-source-han-sans:cn
1219 Older programs such as @command{xterm} do not use Fontconfig and instead
1220 rely on server-side font rendering. Such programs require to specify a
1221 full name of a font using XLFD (X Logical Font Description), like this:
1224 -*-dejavu sans-medium-r-normal-*-*-100-*-*-*-*-*-1
1227 To be able to use such full names for the TrueType fonts installed in
1228 your Guix profile, you need to extend the font path of the X server:
1231 xset +fp ~/.guix-profile/share/fonts/truetype
1234 After that, you can run @code{xlsfonts} (from @code{xlsfonts} package)
1235 to make sure your TrueType fonts are listed there.
1237 @subsection X.509 Certificates
1239 The @code{nss-certs} package provides X.509 certificates, which allow
1240 programs to authenticate Web servers accessed over HTTPS.
1242 When using Guix on a foreign distro, you can install this package and
1243 define the relevant environment variables so that packages know where to
1244 look for certificates. @xref{X.509 Certificates}, for detailed
1247 @subsection Emacs Packages
1249 When you install Emacs packages with Guix, the elisp files may be placed
1250 either in @file{$HOME/.guix-profile/share/emacs/site-lisp/} or in
1252 @file{$HOME/.guix-profile/share/emacs/site-lisp/guix.d/}. The latter
1253 directory exists because potentially there may exist thousands of Emacs
1254 packages and storing all their files in a single directory may be not
1255 reliable (because of name conflicts). So we think using a separate
1256 directory for each package is a good idea. It is very similar to how
1257 the Emacs package system organizes the file structure (@pxref{Package
1258 Files,,, emacs, The GNU Emacs Manual}).
1260 By default, Emacs (installed with Guix) ``knows'' where these packages
1261 are placed, so you do not need to perform any configuration. If, for
1262 some reason, you want to avoid auto-loading Emacs packages installed
1263 with Guix, you can do so by running Emacs with @code{--no-site-file}
1264 option (@pxref{Init File,,, emacs, The GNU Emacs Manual}).
1268 @c *********************************************************************
1269 @node Package Management
1270 @chapter Package Management
1272 The purpose of GNU Guix is to allow users to easily install, upgrade, and
1273 remove software packages, without having to know about their build
1274 procedures or dependencies. Guix also goes beyond this obvious set of
1277 This chapter describes the main features of Guix, as well as the package
1278 management tools it provides. Two user interfaces are provided for
1279 routine package management tasks: A command-line interface described below
1280 (@pxref{Invoking guix package, @code{guix package}}), as well as a visual user
1281 interface in Emacs described in a subsequent chapter (@pxref{Emacs Interface}).
1284 * Features:: How Guix will make your life brighter.
1285 * Invoking guix package:: Package installation, removal, etc.
1286 * Substitutes:: Downloading pre-built binaries.
1287 * Packages with Multiple Outputs:: Single source package, multiple outputs.
1288 * Invoking guix gc:: Running the garbage collector.
1289 * Invoking guix pull:: Fetching the latest Guix and distribution.
1290 * Invoking guix archive:: Exporting and importing store files.
1296 When using Guix, each package ends up in the @dfn{package store}, in its
1297 own directory---something that resembles
1298 @file{/gnu/store/xxx-package-1.2}, where @code{xxx} is a base32 string
1299 (note that Guix comes with an Emacs extension to shorten those file
1300 names, @pxref{Emacs Prettify}.)
1302 Instead of referring to these directories, users have their own
1303 @dfn{profile}, which points to the packages that they actually want to
1304 use. These profiles are stored within each user's home directory, at
1305 @code{$HOME/.guix-profile}.
1307 For example, @code{alice} installs GCC 4.7.2. As a result,
1308 @file{/home/alice/.guix-profile/bin/gcc} points to
1309 @file{/gnu/store/@dots{}-gcc-4.7.2/bin/gcc}. Now, on the same machine,
1310 @code{bob} had already installed GCC 4.8.0. The profile of @code{bob}
1311 simply continues to point to
1312 @file{/gnu/store/@dots{}-gcc-4.8.0/bin/gcc}---i.e., both versions of GCC
1313 coexist on the same system without any interference.
1315 The @command{guix package} command is the central tool to manage
1316 packages (@pxref{Invoking guix package}). It operates on the per-user
1317 profiles, and can be used @emph{with normal user privileges}.
1319 The command provides the obvious install, remove, and upgrade
1320 operations. Each invocation is actually a @emph{transaction}: either
1321 the specified operation succeeds, or nothing happens. Thus, if the
1322 @command{guix package} process is terminated during the transaction,
1323 or if a power outage occurs during the transaction, then the user's
1324 profile remains in its previous state, and remains usable.
1326 In addition, any package transaction may be @emph{rolled back}. So, if,
1327 for example, an upgrade installs a new version of a package that turns
1328 out to have a serious bug, users may roll back to the previous instance
1329 of their profile, which was known to work well. Similarly, the global
1330 system configuration on GuixSD is subject to
1331 transactional upgrades and roll-back
1332 (@pxref{Using the Configuration System}).
1334 All packages in the package store may be @emph{garbage-collected}.
1335 Guix can determine which packages are still referenced by user
1336 profiles, and remove those that are provably no longer referenced
1337 (@pxref{Invoking guix gc}). Users may also explicitly remove old
1338 generations of their profile so that the packages they refer to can be
1341 @cindex reproducibility
1342 @cindex reproducible builds
1343 Finally, Guix takes a @dfn{purely functional} approach to package
1344 management, as described in the introduction (@pxref{Introduction}).
1345 Each @file{/gnu/store} package directory name contains a hash of all the
1346 inputs that were used to build that package---compiler, libraries, build
1347 scripts, etc. This direct correspondence allows users to make sure a
1348 given package installation matches the current state of their
1349 distribution. It also helps maximize @dfn{build reproducibility}:
1350 thanks to the isolated build environments that are used, a given build
1351 is likely to yield bit-identical files when performed on different
1352 machines (@pxref{Invoking guix-daemon, container}).
1355 This foundation allows Guix to support @dfn{transparent binary/source
1356 deployment}. When a pre-built binary for a @file{/gnu/store} item is
1357 available from an external source---a @dfn{substitute}, Guix just
1358 downloads it and unpacks it;
1359 otherwise, it builds the package from source, locally
1360 (@pxref{Substitutes}). Because build results are usually bit-for-bit
1361 reproducible, users do not have to trust servers that provide
1362 substitutes: they can force a local build and @emph{challenge} providers
1363 (@pxref{Invoking guix challenge}).
1365 Control over the build environment is a feature that is also useful for
1366 developers. The @command{guix environment} command allows developers of
1367 a package to quickly set up the right development environment for their
1368 package, without having to manually install the dependencies of the
1369 package into their profile (@pxref{Invoking guix environment}).
1371 @node Invoking guix package
1372 @section Invoking @command{guix package}
1374 The @command{guix package} command is the tool that allows users to
1375 install, upgrade, and remove packages, as well as rolling back to
1376 previous configurations. It operates only on the user's own profile,
1377 and works with normal user privileges (@pxref{Features}). Its syntax
1381 guix package @var{options}
1384 Primarily, @var{options} specifies the operations to be performed during
1385 the transaction. Upon completion, a new profile is created, but
1386 previous @dfn{generations} of the profile remain available, should the user
1389 For example, to remove @code{lua} and install @code{guile} and
1390 @code{guile-cairo} in a single transaction:
1393 guix package -r lua -i guile guile-cairo
1396 @command{guix package} also supports a @dfn{declarative approach}
1397 whereby the user specifies the exact set of packages to be available and
1398 passes it @i{via} the @option{--manifest} option
1399 (@pxref{profile-manifest, @option{--manifest}}).
1401 For each user, a symlink to the user's default profile is automatically
1402 created in @file{$HOME/.guix-profile}. This symlink always points to the
1403 current generation of the user's default profile. Thus, users can add
1404 @file{$HOME/.guix-profile/bin} to their @code{PATH} environment
1405 variable, and so on.
1406 @cindex search paths
1407 If you are not using the Guix System Distribution, consider adding the
1408 following lines to your @file{~/.bash_profile} (@pxref{Bash Startup
1409 Files,,, bash, The GNU Bash Reference Manual}) so that newly-spawned
1410 shells get all the right environment variable definitions:
1413 GUIX_PROFILE="$HOME/.guix-profile" \
1414 source "$HOME/.guix-profile/etc/profile"
1417 In a multi-user setup, user profiles are stored in a place registered as
1418 a @dfn{garbage-collector root}, which @file{$HOME/.guix-profile} points
1419 to (@pxref{Invoking guix gc}). That directory is normally
1420 @code{@var{localstatedir}/profiles/per-user/@var{user}}, where
1421 @var{localstatedir} is the value passed to @code{configure} as
1422 @code{--localstatedir}, and @var{user} is the user name. The
1423 @file{per-user} directory is created when @command{guix-daemon} is
1424 started, and the @var{user} sub-directory is created by @command{guix
1427 The @var{options} can be among the following:
1431 @item --install=@var{package} @dots{}
1432 @itemx -i @var{package} @dots{}
1433 Install the specified @var{package}s.
1435 Each @var{package} may specify either a simple package name, such as
1436 @code{guile}, or a package name followed by an at-sign and version number,
1437 such as @code{guile@@1.8.8} or simply @code{guile@@1.8} (in the latter
1438 case, the newest version prefixed by @code{1.8} is selected.)
1440 If no version number is specified, the
1441 newest available version will be selected. In addition, @var{package}
1442 may contain a colon, followed by the name of one of the outputs of the
1443 package, as in @code{gcc:doc} or @code{binutils@@2.22:lib}
1444 (@pxref{Packages with Multiple Outputs}). Packages with a corresponding
1445 name (and optionally version) are searched for among the GNU
1446 distribution modules (@pxref{Package Modules}).
1448 @cindex propagated inputs
1449 Sometimes packages have @dfn{propagated inputs}: these are dependencies
1450 that automatically get installed along with the required package
1451 (@pxref{package-propagated-inputs, @code{propagated-inputs} in
1452 @code{package} objects}, for information about propagated inputs in
1453 package definitions).
1455 @anchor{package-cmd-propagated-inputs}
1456 An example is the GNU MPC library: its C header files refer to those of
1457 the GNU MPFR library, which in turn refer to those of the GMP library.
1458 Thus, when installing MPC, the MPFR and GMP libraries also get installed
1459 in the profile; removing MPC also removes MPFR and GMP---unless they had
1460 also been explicitly installed by the user.
1462 Besides, packages sometimes rely on the definition of environment
1463 variables for their search paths (see explanation of
1464 @code{--search-paths} below). Any missing or possibly incorrect
1465 environment variable definitions are reported here.
1467 @item --install-from-expression=@var{exp}
1469 Install the package @var{exp} evaluates to.
1471 @var{exp} must be a Scheme expression that evaluates to a
1472 @code{<package>} object. This option is notably useful to disambiguate
1473 between same-named variants of a package, with expressions such as
1474 @code{(@@ (gnu packages base) guile-final)}.
1476 Note that this option installs the first output of the specified
1477 package, which may be insufficient when needing a specific output of a
1478 multiple-output package.
1480 @item --install-from-file=@var{file}
1481 @itemx -f @var{file}
1482 Install the package that the code within @var{file} evaluates to.
1484 As an example, @var{file} might contain a definition like this
1485 (@pxref{Defining Packages}):
1488 @verbatiminclude package-hello.scm
1491 Developers may find it useful to include such a @file{guix.scm} file
1492 in the root of their project source tree that can be used to test
1493 development snapshots and create reproducible development environments
1494 (@pxref{Invoking guix environment}).
1496 @item --remove=@var{package} @dots{}
1497 @itemx -r @var{package} @dots{}
1498 Remove the specified @var{package}s.
1500 As for @code{--install}, each @var{package} may specify a version number
1501 and/or output name in addition to the package name. For instance,
1502 @code{-r glibc:debug} would remove the @code{debug} output of
1505 @item --upgrade[=@var{regexp} @dots{}]
1506 @itemx -u [@var{regexp} @dots{}]
1507 Upgrade all the installed packages. If one or more @var{regexp}s are
1508 specified, upgrade only installed packages whose name matches a
1509 @var{regexp}. Also see the @code{--do-not-upgrade} option below.
1511 Note that this upgrades package to the latest version of packages found
1512 in the distribution currently installed. To update your distribution,
1513 you should regularly run @command{guix pull} (@pxref{Invoking guix
1516 @item --do-not-upgrade[=@var{regexp} @dots{}]
1517 When used together with the @code{--upgrade} option, do @emph{not}
1518 upgrade any packages whose name matches a @var{regexp}. For example, to
1519 upgrade all packages in the current profile except those containing the
1520 substring ``emacs'':
1523 $ guix package --upgrade . --do-not-upgrade emacs
1526 @item @anchor{profile-manifest}--manifest=@var{file}
1527 @itemx -m @var{file}
1528 @cindex profile declaration
1529 @cindex profile manifest
1530 Create a new generation of the profile from the manifest object
1531 returned by the Scheme code in @var{file}.
1533 This allows you to @emph{declare} the profile's contents rather than
1534 constructing it through a sequence of @code{--install} and similar
1535 commands. The advantage is that @var{file} can be put under version
1536 control, copied to different machines to reproduce the same profile, and
1539 @c FIXME: Add reference to (guix profile) documentation when available.
1540 @var{file} must return a @dfn{manifest} object, which is roughly a list
1543 @findex packages->manifest
1545 (use-package-modules guile emacs)
1550 ;; Use a specific package output.
1551 (list guile-2.0 "debug")))
1555 Roll back to the previous @dfn{generation} of the profile---i.e., undo
1556 the last transaction.
1558 When combined with options such as @code{--install}, roll back occurs
1559 before any other actions.
1561 When rolling back from the first generation that actually contains
1562 installed packages, the profile is made to point to the @dfn{zeroth
1563 generation}, which contains no files apart from its own metadata.
1565 After having rolled back, installing, removing, or upgrading packages
1566 overwrites previous future generations. Thus, the history of the
1567 generations in a profile is always linear.
1569 @item --switch-generation=@var{pattern}
1570 @itemx -S @var{pattern}
1571 Switch to a particular generation defined by @var{pattern}.
1573 @var{pattern} may be either a generation number or a number prefixed
1574 with ``+'' or ``-''. The latter means: move forward/backward by a
1575 specified number of generations. For example, if you want to return to
1576 the latest generation after @code{--roll-back}, use
1577 @code{--switch-generation=+1}.
1579 The difference between @code{--roll-back} and
1580 @code{--switch-generation=-1} is that @code{--switch-generation} will
1581 not make a zeroth generation, so if a specified generation does not
1582 exist, the current generation will not be changed.
1584 @item --search-paths[=@var{kind}]
1585 @cindex search paths
1586 Report environment variable definitions, in Bash syntax, that may be
1587 needed in order to use the set of installed packages. These environment
1588 variables are used to specify @dfn{search paths} for files used by some
1589 of the installed packages.
1591 For example, GCC needs the @code{CPATH} and @code{LIBRARY_PATH}
1592 environment variables to be defined so it can look for headers and
1593 libraries in the user's profile (@pxref{Environment Variables,,, gcc,
1594 Using the GNU Compiler Collection (GCC)}). If GCC and, say, the C
1595 library are installed in the profile, then @code{--search-paths} will
1596 suggest setting these variables to @code{@var{profile}/include} and
1597 @code{@var{profile}/lib}, respectively.
1599 The typical use case is to define these environment variables in the
1603 $ eval `guix package --search-paths`
1606 @var{kind} may be one of @code{exact}, @code{prefix}, or @code{suffix},
1607 meaning that the returned environment variable definitions will either
1608 be exact settings, or prefixes or suffixes of the current value of these
1609 variables. When omitted, @var{kind} defaults to @code{exact}.
1611 This option can also be used to compute the @emph{combined} search paths
1612 of several profiles. Consider this example:
1615 $ guix package -p foo -i guile
1616 $ guix package -p bar -i guile-json
1617 $ guix package -p foo -p bar --search-paths
1620 The last command above reports about the @code{GUILE_LOAD_PATH}
1621 variable, even though, taken individually, neither @file{foo} nor
1622 @file{bar} would lead to that recommendation.
1625 @item --profile=@var{profile}
1626 @itemx -p @var{profile}
1627 Use @var{profile} instead of the user's default profile.
1630 Produce verbose output. In particular, emit the build log of the
1631 environment on the standard error port.
1634 Use the bootstrap Guile to build the profile. This option is only
1635 useful to distribution developers.
1639 In addition to these actions, @command{guix package} supports the
1640 following options to query the current state of a profile, or the
1641 availability of packages:
1645 @item --search=@var{regexp}
1646 @itemx -s @var{regexp}
1647 @cindex searching for packages
1648 List the available packages whose name, synopsis, or description matches
1649 @var{regexp}. Print all the metadata of matching packages in
1650 @code{recutils} format (@pxref{Top, GNU recutils databases,, recutils,
1651 GNU recutils manual}).
1653 This allows specific fields to be extracted using the @command{recsel}
1654 command, for instance:
1657 $ guix package -s malloc | recsel -p name,version
1665 Similarly, to show the name of all the packages available under the
1666 terms of the GNU@tie{}LGPL version 3:
1669 $ guix package -s "" | recsel -p name -e 'license ~ "LGPL 3"'
1676 It is also possible to refine search results using several @code{-s}
1677 flags. For example, the following command returns a list of board
1681 $ guix package -s '\<board\>' -s game | recsel -p name
1686 If we were to omit @code{-s game}, we would also get software packages
1687 that deal with printed circuit boards; removing the angle brackets
1688 around @code{board} would further add packages that have to do with
1691 And now for a more elaborate example. The following command searches
1692 for cryptographic libraries, filters out Haskell, Perl, Python, and Ruby
1693 libraries, and prints the name and synopsis of the matching packages:
1696 $ guix package -s crypto -s library | \
1697 recsel -e '! (name ~ "^(ghc|perl|python|ruby)")' -p name,synopsis
1701 @xref{Selection Expressions,,, recutils, GNU recutils manual}, for more
1702 information on @dfn{selection expressions} for @code{recsel -e}.
1704 @item --show=@var{package}
1705 Show details about @var{package}, taken from the list of available packages, in
1706 @code{recutils} format (@pxref{Top, GNU recutils databases,, recutils, GNU
1710 $ guix package --show=python | recsel -p name,version
1718 You may also specify the full name of a package to only get details about a
1719 specific version of it:
1721 $ guix package --show=python@@3.4 | recsel -p name,version
1728 @item --list-installed[=@var{regexp}]
1729 @itemx -I [@var{regexp}]
1730 List the currently installed packages in the specified profile, with the
1731 most recently installed packages shown last. When @var{regexp} is
1732 specified, list only installed packages whose name matches @var{regexp}.
1734 For each installed package, print the following items, separated by
1735 tabs: the package name, its version string, the part of the package that
1736 is installed (for instance, @code{out} for the default output,
1737 @code{include} for its headers, etc.), and the path of this package in
1740 @item --list-available[=@var{regexp}]
1741 @itemx -A [@var{regexp}]
1742 List packages currently available in the distribution for this system
1743 (@pxref{GNU Distribution}). When @var{regexp} is specified, list only
1744 installed packages whose name matches @var{regexp}.
1746 For each package, print the following items separated by tabs: its name,
1747 its version string, the parts of the package (@pxref{Packages with
1748 Multiple Outputs}), and the source location of its definition.
1750 @item --list-generations[=@var{pattern}]
1751 @itemx -l [@var{pattern}]
1752 Return a list of generations along with their creation dates; for each
1753 generation, show the installed packages, with the most recently
1754 installed packages shown last. Note that the zeroth generation is never
1757 For each installed package, print the following items, separated by
1758 tabs: the name of a package, its version string, the part of the package
1759 that is installed (@pxref{Packages with Multiple Outputs}), and the
1760 location of this package in the store.
1762 When @var{pattern} is used, the command returns only matching
1763 generations. Valid patterns include:
1766 @item @emph{Integers and comma-separated integers}. Both patterns denote
1767 generation numbers. For instance, @code{--list-generations=1} returns
1770 And @code{--list-generations=1,8,2} outputs three generations in the
1771 specified order. Neither spaces nor trailing commas are allowed.
1773 @item @emph{Ranges}. @code{--list-generations=2..9} prints the
1774 specified generations and everything in between. Note that the start of
1775 a range must be smaller than its end.
1777 It is also possible to omit the endpoint. For example,
1778 @code{--list-generations=2..}, returns all generations starting from the
1781 @item @emph{Durations}. You can also get the last @emph{N}@tie{}days, weeks,
1782 or months by passing an integer along with the first letter of the
1783 duration. For example, @code{--list-generations=20d} lists generations
1784 that are up to 20 days old.
1787 @item --delete-generations[=@var{pattern}]
1788 @itemx -d [@var{pattern}]
1789 When @var{pattern} is omitted, delete all generations except the current
1792 This command accepts the same patterns as @option{--list-generations}.
1793 When @var{pattern} is specified, delete the matching generations. When
1794 @var{pattern} specifies a duration, generations @emph{older} than the
1795 specified duration match. For instance, @code{--delete-generations=1m}
1796 deletes generations that are more than one month old.
1798 If the current generation matches, it is @emph{not} deleted. Also, the
1799 zeroth generation is never deleted.
1801 Note that deleting generations prevents rolling back to them.
1802 Consequently, this command must be used with care.
1806 Finally, since @command{guix package} may actually start build
1807 processes, it supports all the common build options (@pxref{Common Build
1808 Options}). It also supports package transformation options, such as
1809 @option{--with-source} (@pxref{Package Transformation Options}).
1810 However, note that package transformations are lost when upgrading; to
1811 preserve transformations across upgrades, you should define your own
1812 package variant in a Guile module and add it to @code{GUIX_PACKAGE_PATH}
1813 (@pxref{Defining Packages}).
1817 @section Substitutes
1820 @cindex pre-built binaries
1821 Guix supports transparent source/binary deployment, which means that it
1822 can either build things locally, or download pre-built items from a
1823 server. We call these pre-built items @dfn{substitutes}---they are
1824 substitutes for local build results. In many cases, downloading a
1825 substitute is much faster than building things locally.
1827 Substitutes can be anything resulting from a derivation build
1828 (@pxref{Derivations}). Of course, in the common case, they are
1829 pre-built package binaries, but source tarballs, for instance, which
1830 also result from derivation builds, can be available as substitutes.
1832 The @code{hydra.gnu.org} server is a front-end to a build farm that
1833 builds packages from the GNU distribution continuously for some
1834 architectures, and makes them available as substitutes (@pxref{Emacs
1835 Hydra}, for information on how to query the continuous integration
1836 server). This is the
1837 default source of substitutes; it can be overridden by passing the
1838 @option{--substitute-urls} option either to @command{guix-daemon}
1839 (@pxref{daemon-substitute-urls,, @code{guix-daemon --substitute-urls}})
1840 or to client tools such as @command{guix package}
1841 (@pxref{client-substitute-urls,, client @option{--substitute-urls}
1844 Substitute URLs can be either HTTP or HTTPS@footnote{For HTTPS access,
1845 the Guile bindings of GnuTLS must be installed. @xref{Requirements}.}
1846 HTTPS is recommended because communications are encrypted; conversely,
1847 using HTTP makes all communications visible to an eavesdropper, who
1848 could use the information gathered to determine, for instance, whether
1849 your system has unpatched security vulnerabilities.
1852 @cindex digital signatures
1853 To allow Guix to download substitutes from @code{hydra.gnu.org} or a
1855 must add its public key to the access control list (ACL) of archive
1856 imports, using the @command{guix archive} command (@pxref{Invoking guix
1857 archive}). Doing so implies that you trust @code{hydra.gnu.org} to not
1858 be compromised and to serve genuine substitutes.
1860 This public key is installed along with Guix, in
1861 @code{@var{prefix}/share/guix/hydra.gnu.org.pub}, where @var{prefix} is
1862 the installation prefix of Guix. If you installed Guix from source,
1863 make sure you checked the GPG signature of
1864 @file{guix-@value{VERSION}.tar.gz}, which contains this public key file.
1865 Then, you can run something like this:
1868 # guix archive --authorize < hydra.gnu.org.pub
1871 Once this is in place, the output of a command like @code{guix build}
1872 should change from something like:
1875 $ guix build emacs --dry-run
1876 The following derivations would be built:
1877 /gnu/store/yr7bnx8xwcayd6j95r2clmkdl1qh688w-emacs-24.3.drv
1878 /gnu/store/x8qsh1hlhgjx6cwsjyvybnfv2i37z23w-dbus-1.6.4.tar.gz.drv
1879 /gnu/store/1ixwp12fl950d15h2cj11c73733jay0z-alsa-lib-1.0.27.1.tar.bz2.drv
1880 /gnu/store/nlma1pw0p603fpfiqy7kn4zm105r5dmw-util-linux-2.21.drv
1888 $ guix build emacs --dry-run
1889 The following files would be downloaded:
1890 /gnu/store/pk3n22lbq6ydamyymqkkz7i69wiwjiwi-emacs-24.3
1891 /gnu/store/2ygn4ncnhrpr61rssa6z0d9x22si0va3-libjpeg-8d
1892 /gnu/store/71yz6lgx4dazma9dwn2mcjxaah9w77jq-cairo-1.12.16
1893 /gnu/store/7zdhgp0n1518lvfn8mb96sxqfmvqrl7v-libxrender-0.9.7
1898 This indicates that substitutes from @code{hydra.gnu.org} are usable and
1899 will be downloaded, when possible, for future builds.
1901 Guix ignores substitutes that are not signed, or that are not signed by
1902 one of the keys listed in the ACL. It also detects and raises an error
1903 when attempting to use a substitute that has been tampered with.
1906 Substitutes are downloaded over HTTP or HTTPS.
1907 The @code{http_proxy} environment
1908 variable can be set in the environment of @command{guix-daemon} and is
1909 honored for downloads of substitutes. Note that the value of
1910 @code{http_proxy} in the environment where @command{guix build},
1911 @command{guix package}, and other client commands are run has
1912 @emph{absolutely no effect}.
1914 When using HTTPS, the server's X.509 certificate is @emph{not} validated
1915 (in other words, the server is not authenticated), contrary to what
1916 HTTPS clients such as Web browsers usually do. This is because Guix
1917 authenticates substitute information itself, as explained above, which
1918 is what we care about (whereas X.509 certificates are about
1919 authenticating bindings between domain names and public keys.)
1921 The substitute mechanism can be disabled globally by running
1922 @code{guix-daemon} with @code{--no-substitutes} (@pxref{Invoking
1923 guix-daemon}). It can also be disabled temporarily by passing the
1924 @code{--no-substitutes} option to @command{guix package}, @command{guix
1925 build}, and other command-line tools.
1928 @unnumberedsubsec On Trusting Binaries
1930 Today, each individual's control over their own computing is at the
1931 mercy of institutions, corporations, and groups with enough power and
1932 determination to subvert the computing infrastructure and exploit its
1933 weaknesses. While using @code{hydra.gnu.org} substitutes can be
1934 convenient, we encourage users to also build on their own, or even run
1935 their own build farm, such that @code{hydra.gnu.org} is less of an
1936 interesting target. One way to help is by publishing the software you
1937 build using @command{guix publish} so that others have one more choice
1938 of server to download substitutes from (@pxref{Invoking guix publish}).
1940 Guix has the foundations to maximize build reproducibility
1941 (@pxref{Features}). In most cases, independent builds of a given
1942 package or derivation should yield bit-identical results. Thus, through
1943 a diverse set of independent package builds, we can strengthen the
1944 integrity of our systems. The @command{guix challenge} command aims to
1945 help users assess substitute servers, and to assist developers in
1946 finding out about non-deterministic package builds (@pxref{Invoking guix
1947 challenge}). Similarly, the @option{--check} option of @command{guix
1948 build} allows users to check whether previously-installed substitutes
1949 are genuine by rebuilding them locally (@pxref{build-check,
1950 @command{guix build --check}}).
1952 In the future, we want Guix to have support to publish and retrieve
1953 binaries to/from other users, in a peer-to-peer fashion. If you would
1954 like to discuss this project, join us on @email{guix-devel@@gnu.org}.
1957 @node Packages with Multiple Outputs
1958 @section Packages with Multiple Outputs
1960 @cindex multiple-output packages
1961 @cindex package outputs
1963 Often, packages defined in Guix have a single @dfn{output}---i.e., the
1964 source package leads to exactly one directory in the store. When running
1965 @command{guix package -i glibc}, one installs the default output of the
1966 GNU libc package; the default output is called @code{out}, but its name
1967 can be omitted as shown in this command. In this particular case, the
1968 default output of @code{glibc} contains all the C header files, shared
1969 libraries, static libraries, Info documentation, and other supporting
1972 Sometimes it is more appropriate to separate the various types of files
1973 produced from a single source package into separate outputs. For
1974 instance, the GLib C library (used by GTK+ and related packages)
1975 installs more than 20 MiB of reference documentation as HTML pages.
1976 To save space for users who do not need it, the documentation goes to a
1977 separate output, called @code{doc}. To install the main GLib output,
1978 which contains everything but the documentation, one would run:
1981 guix package -i glib
1984 The command to install its documentation is:
1987 guix package -i glib:doc
1990 Some packages install programs with different ``dependency footprints''.
1991 For instance, the WordNet package installs both command-line tools and
1992 graphical user interfaces (GUIs). The former depend solely on the C
1993 library, whereas the latter depend on Tcl/Tk and the underlying X
1994 libraries. In this case, we leave the command-line tools in the default
1995 output, whereas the GUIs are in a separate output. This allows users
1996 who do not need the GUIs to save space. The @command{guix size} command
1997 can help find out about such situations (@pxref{Invoking guix size}).
1998 @command{guix graph} can also be helpful (@pxref{Invoking guix graph}).
2000 There are several such multiple-output packages in the GNU distribution.
2001 Other conventional output names include @code{lib} for libraries and
2002 possibly header files, @code{bin} for stand-alone programs, and
2003 @code{debug} for debugging information (@pxref{Installing Debugging
2004 Files}). The outputs of a packages are listed in the third column of
2005 the output of @command{guix package --list-available} (@pxref{Invoking
2009 @node Invoking guix gc
2010 @section Invoking @command{guix gc}
2012 @cindex garbage collector
2013 Packages that are installed, but not used, may be @dfn{garbage-collected}.
2014 The @command{guix gc} command allows users to explicitly run the garbage
2015 collector to reclaim space from the @file{/gnu/store} directory. It is
2016 the @emph{only} way to remove files from @file{/gnu/store}---removing
2017 files or directories manually may break it beyond repair!
2019 The garbage collector has a set of known @dfn{roots}: any file under
2020 @file{/gnu/store} reachable from a root is considered @dfn{live} and
2021 cannot be deleted; any other file is considered @dfn{dead} and may be
2022 deleted. The set of garbage collector roots includes default user
2023 profiles, and may be augmented with @command{guix build --root}, for
2024 example (@pxref{Invoking guix build}).
2026 Prior to running @code{guix gc --collect-garbage} to make space, it is
2027 often useful to remove old generations from user profiles; that way, old
2028 package builds referenced by those generations can be reclaimed. This
2029 is achieved by running @code{guix package --delete-generations}
2030 (@pxref{Invoking guix package}).
2032 The @command{guix gc} command has three modes of operation: it can be
2033 used to garbage-collect any dead files (the default), to delete specific
2034 files (the @code{--delete} option), to print garbage-collector
2035 information, or for more advanced queries. The garbage collection
2036 options are as follows:
2039 @item --collect-garbage[=@var{min}]
2040 @itemx -C [@var{min}]
2041 Collect garbage---i.e., unreachable @file{/gnu/store} files and
2042 sub-directories. This is the default operation when no option is
2045 When @var{min} is given, stop once @var{min} bytes have been collected.
2046 @var{min} may be a number of bytes, or it may include a unit as a
2047 suffix, such as @code{MiB} for mebibytes and @code{GB} for gigabytes
2048 (@pxref{Block size, size specifications,, coreutils, GNU Coreutils}).
2050 When @var{min} is omitted, collect all the garbage.
2052 @item --free-space=@var{free}
2053 @itemx -F @var{free}
2054 Collect garbage until @var{free} space is available under
2055 @file{/gnu/store}, if possible; @var{free} denotes storage space, such
2056 as @code{500MiB}, as described above.
2058 When @var{free} or more is already available in @file{/gnu/store}, do
2059 nothing and exit immediately.
2063 Attempt to delete all the store files and directories specified as
2064 arguments. This fails if some of the files are not in the store, or if
2065 they are still live.
2067 @item --list-failures
2068 List store items corresponding to cached build failures.
2070 This prints nothing unless the daemon was started with
2071 @option{--cache-failures} (@pxref{Invoking guix-daemon,
2072 @option{--cache-failures}}).
2074 @item --clear-failures
2075 Remove the specified store items from the failed-build cache.
2077 Again, this option only makes sense when the daemon is started with
2078 @option{--cache-failures}. Otherwise, it does nothing.
2081 Show the list of dead files and directories still present in the
2082 store---i.e., files and directories no longer reachable from any root.
2085 Show the list of live store files and directories.
2089 In addition, the references among existing store files can be queried:
2095 List the references (respectively, the referrers) of store files given
2101 List the requisites of the store files passed as arguments. Requisites
2102 include the store files themselves, their references, and the references
2103 of these, recursively. In other words, the returned list is the
2104 @dfn{transitive closure} of the store files.
2106 @xref{Invoking guix size}, for a tool to profile the size of the closure
2107 of an element. @xref{Invoking guix graph}, for a tool to visualize
2108 the graph of references.
2112 Lastly, the following options allow you to check the integrity of the
2113 store and to control disk usage.
2117 @item --verify[=@var{options}]
2118 @cindex integrity, of the store
2119 @cindex integrity checking
2120 Verify the integrity of the store.
2122 By default, make sure that all the store items marked as valid in the
2123 database of the daemon actually exist in @file{/gnu/store}.
2125 When provided, @var{options} must be a comma-separated list containing one
2126 or more of @code{contents} and @code{repair}.
2128 When passing @option{--verify=contents}, the daemon computes the
2129 content hash of each store item and compares it against its hash in the
2130 database. Hash mismatches are reported as data corruptions. Because it
2131 traverses @emph{all the files in the store}, this command can take a
2132 long time, especially on systems with a slow disk drive.
2134 @cindex repairing the store
2135 Using @option{--verify=repair} or @option{--verify=contents,repair}
2136 causes the daemon to try to repair corrupt store items by fetching
2137 substitutes for them (@pxref{Substitutes}). Because repairing is not
2138 atomic, and thus potentially dangerous, it is available only to the
2139 system administrator.
2142 @cindex deduplication
2143 Optimize the store by hard-linking identical files---this is
2144 @dfn{deduplication}.
2146 The daemon performs deduplication after each successful build or archive
2147 import, unless it was started with @code{--disable-deduplication}
2148 (@pxref{Invoking guix-daemon, @code{--disable-deduplication}}). Thus,
2149 this option is primarily useful when the daemon was running with
2150 @code{--disable-deduplication}.
2154 @node Invoking guix pull
2155 @section Invoking @command{guix pull}
2157 Packages are installed or upgraded to the latest version available in
2158 the distribution currently available on your local machine. To update
2159 that distribution, along with the Guix tools, you must run @command{guix
2160 pull}: the command downloads the latest Guix source code and package
2161 descriptions, and deploys it.
2163 On completion, @command{guix package} will use packages and package
2164 versions from this just-retrieved copy of Guix. Not only that, but all
2165 the Guix commands and Scheme modules will also be taken from that latest
2166 version. New @command{guix} sub-commands added by the update also
2169 Any user can update their Guix copy using @command{guix pull}, and the
2170 effect is limited to the user who run @command{guix pull}. For
2171 instance, when user @code{root} runs @command{guix pull}, this has no
2172 effect on the version of Guix that user @code{alice} sees, and vice
2173 versa@footnote{Under the hood, @command{guix pull} updates the
2174 @file{~/.config/guix/latest} symbolic link to point to the latest Guix,
2175 and the @command{guix} command loads code from there.}.
2177 The @command{guix pull} command is usually invoked with no arguments,
2178 but it supports the following options:
2182 Produce verbose output, writing build logs to the standard error output.
2184 @item --url=@var{url}
2185 Download the source tarball of Guix from @var{url}.
2187 By default, the tarball is taken from its canonical address at
2188 @code{gnu.org}, for the stable branch of Guix.
2191 Use the bootstrap Guile to build the latest Guix. This option is only
2192 useful to Guix developers.
2196 @node Invoking guix archive
2197 @section Invoking @command{guix archive}
2199 The @command{guix archive} command allows users to @dfn{export} files
2200 from the store into a single archive, and to later @dfn{import} them.
2201 In particular, it allows store files to be transferred from one machine
2202 to the store on another machine.
2204 To export store files as an archive to standard output, run:
2207 guix archive --export @var{options} @var{specifications}...
2210 @var{specifications} may be either store file names or package
2211 specifications, as for @command{guix package} (@pxref{Invoking guix
2212 package}). For instance, the following command creates an archive
2213 containing the @code{gui} output of the @code{git} package and the main
2214 output of @code{emacs}:
2217 guix archive --export git:gui /gnu/store/...-emacs-24.3 > great.nar
2220 If the specified packages are not built yet, @command{guix archive}
2221 automatically builds them. The build process may be controlled with the
2222 common build options (@pxref{Common Build Options}).
2224 To transfer the @code{emacs} package to a machine connected over SSH,
2228 guix archive --export -r emacs | ssh the-machine guix archive --import
2232 Similarly, a complete user profile may be transferred from one machine
2233 to another like this:
2236 guix archive --export -r $(readlink -f ~/.guix-profile) | \
2237 ssh the-machine guix-archive --import
2241 However, note that, in both examples, all of @code{emacs} and the
2242 profile as well as all of their dependencies are transferred (due to
2243 @code{-r}), regardless of what is already available in the store on the
2244 target machine. The @code{--missing} option can help figure out which
2245 items are missing from the target store.
2247 Archives are stored in the ``Nix archive'' or ``Nar'' format, which is
2248 comparable in spirit to `tar', but with a few noteworthy differences
2249 that make it more appropriate for our purposes. First, rather than
2250 recording all Unix metadata for each file, the Nar format only mentions
2251 the file type (regular, directory, or symbolic link); Unix permissions
2252 and owner/group are dismissed. Second, the order in which directory
2253 entries are stored always follows the order of file names according to
2254 the C locale collation order. This makes archive production fully
2257 When exporting, the daemon digitally signs the contents of the archive,
2258 and that digital signature is appended. When importing, the daemon
2259 verifies the signature and rejects the import in case of an invalid
2260 signature or if the signing key is not authorized.
2261 @c FIXME: Add xref to daemon doc about signatures.
2263 The main options are:
2267 Export the specified store files or packages (see below.) Write the
2268 resulting archive to the standard output.
2270 Dependencies are @emph{not} included in the output, unless
2271 @code{--recursive} is passed.
2275 When combined with @code{--export}, this instructs @command{guix
2276 archive} to include dependencies of the given items in the archive.
2277 Thus, the resulting archive is self-contained: it contains the closure
2278 of the exported store items.
2281 Read an archive from the standard input, and import the files listed
2282 therein into the store. Abort if the archive has an invalid digital
2283 signature, or if it is signed by a public key not among the authorized
2284 keys (see @code{--authorize} below.)
2287 Read a list of store file names from the standard input, one per line,
2288 and write on the standard output the subset of these files missing from
2291 @item --generate-key[=@var{parameters}]
2292 @cindex signing, archives
2293 Generate a new key pair for the daemon. This is a prerequisite before
2294 archives can be exported with @code{--export}. Note that this operation
2295 usually takes time, because it needs to gather enough entropy to
2296 generate the key pair.
2298 The generated key pair is typically stored under @file{/etc/guix}, in
2299 @file{signing-key.pub} (public key) and @file{signing-key.sec} (private
2300 key, which must be kept secret.) When @var{parameters} is omitted,
2301 an ECDSA key using the Ed25519 curve is generated, or, for Libgcrypt
2302 versions before 1.6.0, it is a 4096-bit RSA key.
2303 Alternatively, @var{parameters} can specify
2304 @code{genkey} parameters suitable for Libgcrypt (@pxref{General
2305 public-key related Functions, @code{gcry_pk_genkey},, gcrypt, The
2306 Libgcrypt Reference Manual}).
2309 @cindex authorizing, archives
2310 Authorize imports signed by the public key passed on standard input.
2311 The public key must be in ``s-expression advanced format''---i.e., the
2312 same format as the @file{signing-key.pub} file.
2314 The list of authorized keys is kept in the human-editable file
2315 @file{/etc/guix/acl}. The file contains
2316 @url{http://people.csail.mit.edu/rivest/Sexp.txt, ``advanced-format
2317 s-expressions''} and is structured as an access-control list in the
2318 @url{http://theworld.com/~cme/spki.txt, Simple Public-Key Infrastructure
2321 @item --extract=@var{directory}
2322 @itemx -x @var{directory}
2323 Read a single-item archive as served by substitute servers
2324 (@pxref{Substitutes}) and extract it to @var{directory}. This is a
2325 low-level operation needed in only very narrow use cases; see below.
2327 For example, the following command extracts the substitute for Emacs
2328 served by @code{hydra.gnu.org} to @file{/tmp/emacs}:
2332 https://hydra.gnu.org/nar/@dots{}-emacs-24.5 \
2333 | bunzip2 | guix archive -x /tmp/emacs
2336 Single-item archives are different from multiple-item archives produced
2337 by @command{guix archive --export}; they contain a single store item,
2338 and they do @emph{not} embed a signature. Thus this operation does
2339 @emph{no} signature verification and its output should be considered
2342 The primary purpose of this operation is to facilitate inspection of
2343 archive contents coming from possibly untrusted substitute servers.
2347 @c *********************************************************************
2350 @c *********************************************************************
2351 @node Programming Interface
2352 @chapter Programming Interface
2354 GNU Guix provides several Scheme programming interfaces (APIs) to
2355 define, build, and query packages. The first interface allows users to
2356 write high-level package definitions. These definitions refer to
2357 familiar packaging concepts, such as the name and version of a package,
2358 its build system, and its dependencies. These definitions can then be
2359 turned into concrete build actions.
2361 Build actions are performed by the Guix daemon, on behalf of users. In a
2362 standard setup, the daemon has write access to the store---the
2363 @file{/gnu/store} directory---whereas users do not. The recommended
2364 setup also has the daemon perform builds in chroots, under a specific
2365 build users, to minimize interference with the rest of the system.
2368 Lower-level APIs are available to interact with the daemon and the
2369 store. To instruct the daemon to perform a build action, users actually
2370 provide it with a @dfn{derivation}. A derivation is a low-level
2371 representation of the build actions to be taken, and the environment in
2372 which they should occur---derivations are to package definitions what
2373 assembly is to C programs. The term ``derivation'' comes from the fact
2374 that build results @emph{derive} from them.
2376 This chapter describes all these APIs in turn, starting from high-level
2377 package definitions.
2380 * Defining Packages:: Defining new packages.
2381 * Build Systems:: Specifying how packages are built.
2382 * The Store:: Manipulating the package store.
2383 * Derivations:: Low-level interface to package derivations.
2384 * The Store Monad:: Purely functional interface to the store.
2385 * G-Expressions:: Manipulating build expressions.
2388 @node Defining Packages
2389 @section Defining Packages
2391 The high-level interface to package definitions is implemented in the
2392 @code{(guix packages)} and @code{(guix build-system)} modules. As an
2393 example, the package definition, or @dfn{recipe}, for the GNU Hello
2394 package looks like this:
2397 (define-module (gnu packages hello)
2398 #:use-module (guix packages)
2399 #:use-module (guix download)
2400 #:use-module (guix build-system gnu)
2401 #:use-module (guix licenses)
2402 #:use-module (gnu packages gawk))
2404 (define-public hello
2410 (uri (string-append "mirror://gnu/hello/hello-" version
2414 "0ssi1wpaf7plaswqqjwigppsg5fyh99vdlb9kzl7c9lng89ndq1i"))))
2415 (build-system gnu-build-system)
2416 (arguments '(#:configure-flags '("--enable-silent-rules")))
2417 (inputs `(("gawk" ,gawk)))
2418 (synopsis "Hello, GNU world: An example GNU package")
2419 (description "Guess what GNU Hello prints!")
2420 (home-page "http://www.gnu.org/software/hello/")
2425 Without being a Scheme expert, the reader may have guessed the meaning
2426 of the various fields here. This expression binds the variable
2427 @code{hello} to a @code{<package>} object, which is essentially a record
2428 (@pxref{SRFI-9, Scheme records,, guile, GNU Guile Reference Manual}).
2429 This package object can be inspected using procedures found in the
2430 @code{(guix packages)} module; for instance, @code{(package-name hello)}
2431 returns---surprise!---@code{"hello"}.
2433 With luck, you may be able to import part or all of the definition of
2434 the package you are interested in from another repository, using the
2435 @code{guix import} command (@pxref{Invoking guix import}).
2437 In the example above, @var{hello} is defined in a module of its own,
2438 @code{(gnu packages hello)}. Technically, this is not strictly
2439 necessary, but it is convenient to do so: all the packages defined in
2440 modules under @code{(gnu packages @dots{})} are automatically known to
2441 the command-line tools (@pxref{Package Modules}).
2443 There are a few points worth noting in the above package definition:
2447 The @code{source} field of the package is an @code{<origin>} object
2448 (@pxref{origin Reference}, for the complete reference).
2449 Here, the @code{url-fetch} method from @code{(guix download)} is used,
2450 meaning that the source is a file to be downloaded over FTP or HTTP.
2452 The @code{mirror://gnu} prefix instructs @code{url-fetch} to use one of
2453 the GNU mirrors defined in @code{(guix download)}.
2455 The @code{sha256} field specifies the expected SHA256 hash of the file
2456 being downloaded. It is mandatory, and allows Guix to check the
2457 integrity of the file. The @code{(base32 @dots{})} form introduces the
2458 base32 representation of the hash. You can obtain this information with
2459 @code{guix download} (@pxref{Invoking guix download}) and @code{guix
2460 hash} (@pxref{Invoking guix hash}).
2463 When needed, the @code{origin} form can also have a @code{patches} field
2464 listing patches to be applied, and a @code{snippet} field giving a
2465 Scheme expression to modify the source code.
2468 @cindex GNU Build System
2469 The @code{build-system} field specifies the procedure to build the
2470 package (@pxref{Build Systems}). Here, @var{gnu-build-system}
2471 represents the familiar GNU Build System, where packages may be
2472 configured, built, and installed with the usual @code{./configure &&
2473 make && make check && make install} command sequence.
2476 The @code{arguments} field specifies options for the build system
2477 (@pxref{Build Systems}). Here it is interpreted by
2478 @var{gnu-build-system} as a request run @file{configure} with the
2479 @code{--enable-silent-rules} flag.
2485 What about these quote (@code{'}) characters? They are Scheme syntax to
2486 introduce a literal list; @code{'} is synonymous with @code{quote}.
2487 @xref{Expression Syntax, quoting,, guile, GNU Guile Reference Manual},
2488 for details. Here the value of the @code{arguments} field is a list of
2489 arguments passed to the build system down the road, as with @code{apply}
2490 (@pxref{Fly Evaluation, @code{apply},, guile, GNU Guile Reference
2493 The hash-colon (@code{#:}) sequence defines a Scheme @dfn{keyword}
2494 (@pxref{Keywords,,, guile, GNU Guile Reference Manual}), and
2495 @code{#:configure-flags} is a keyword used to pass a keyword argument
2496 to the build system (@pxref{Coding With Keywords,,, guile, GNU Guile
2500 The @code{inputs} field specifies inputs to the build process---i.e.,
2501 build-time or run-time dependencies of the package. Here, we define an
2502 input called @code{"gawk"} whose value is that of the @var{gawk}
2503 variable; @var{gawk} is itself bound to a @code{<package>} object.
2505 @cindex backquote (quasiquote)
2508 @cindex comma (unquote)
2512 @findex unquote-splicing
2513 Again, @code{`} (a backquote, synonymous with @code{quasiquote}) allows
2514 us to introduce a literal list in the @code{inputs} field, while
2515 @code{,} (a comma, synonymous with @code{unquote}) allows us to insert a
2516 value in that list (@pxref{Expression Syntax, unquote,, guile, GNU Guile
2519 Note that GCC, Coreutils, Bash, and other essential tools do not need to
2520 be specified as inputs here. Instead, @var{gnu-build-system} takes care
2521 of ensuring that they are present (@pxref{Build Systems}).
2523 However, any other dependencies need to be specified in the
2524 @code{inputs} field. Any dependency not specified here will simply be
2525 unavailable to the build process, possibly leading to a build failure.
2528 @xref{package Reference}, for a full description of possible fields.
2530 Once a package definition is in place, the
2531 package may actually be built using the @code{guix build} command-line
2532 tool (@pxref{Invoking guix build}). You can easily jump back to the
2533 package definition using the @command{guix edit} command
2534 (@pxref{Invoking guix edit}).
2535 @xref{Packaging Guidelines}, for
2536 more information on how to test package definitions, and
2537 @ref{Invoking guix lint}, for information on how to check a definition
2538 for style conformance.
2540 Finally, updating the package definition to a new upstream version
2541 can be partly automated by the @command{guix refresh} command
2542 (@pxref{Invoking guix refresh}).
2544 Behind the scenes, a derivation corresponding to the @code{<package>}
2545 object is first computed by the @code{package-derivation} procedure.
2546 That derivation is stored in a @code{.drv} file under @file{/gnu/store}.
2547 The build actions it prescribes may then be realized by using the
2548 @code{build-derivations} procedure (@pxref{The Store}).
2550 @deffn {Scheme Procedure} package-derivation @var{store} @var{package} [@var{system}]
2551 Return the @code{<derivation>} object of @var{package} for @var{system}
2552 (@pxref{Derivations}).
2554 @var{package} must be a valid @code{<package>} object, and @var{system}
2555 must be a string denoting the target system type---e.g.,
2556 @code{"x86_64-linux"} for an x86_64 Linux-based GNU system. @var{store}
2557 must be a connection to the daemon, which operates on the store
2558 (@pxref{The Store}).
2562 @cindex cross-compilation
2563 Similarly, it is possible to compute a derivation that cross-builds a
2564 package for some other system:
2566 @deffn {Scheme Procedure} package-cross-derivation @var{store} @
2567 @var{package} @var{target} [@var{system}]
2568 Return the @code{<derivation>} object of @var{package} cross-built from
2569 @var{system} to @var{target}.
2571 @var{target} must be a valid GNU triplet denoting the target hardware
2572 and operating system, such as @code{"mips64el-linux-gnu"}
2573 (@pxref{Configuration Names, GNU configuration triplets,, configure, GNU
2574 Configure and Build System}).
2577 @cindex package transformations
2578 @cindex input rewriting
2579 @cindex dependency tree rewriting
2580 Packages can be manipulated in arbitrary ways. An example of a useful
2581 transformation is @dfn{input rewriting}, whereby the dependency tree of
2582 a package is rewritten by replacing specific inputs by others:
2584 @deffn {Scheme Procedure} package-input-rewriting @var{replacements} @
2585 [@var{rewrite-name}]
2586 Return a procedure that, when passed a package, replaces its direct and
2587 indirect dependencies (but not its implicit inputs) according to
2588 @var{replacements}. @var{replacements} is a list of package pairs; the
2589 first element of each pair is the package to replace, and the second one
2592 Optionally, @var{rewrite-name} is a one-argument procedure that takes
2593 the name of a package and returns its new name after rewrite.
2597 Consider this example:
2600 (define libressl-instead-of-openssl
2601 ;; This is a procedure to replace OPENSSL by LIBRESSL,
2603 (package-input-rewriting `((,openssl . ,libressl))))
2605 (define git-with-libressl
2606 (libressl-instead-of-openssl git))
2610 Here we first define a rewriting procedure that replaces @var{openssl}
2611 with @var{libressl}. Then we use it to define a @dfn{variant} of the
2612 @var{git} package that uses @var{libressl} instead of @var{openssl}.
2613 This is exactly what the @option{--with-input} command-line option does
2614 (@pxref{Package Transformation Options, @option{--with-input}}).
2617 * package Reference :: The package data type.
2618 * origin Reference:: The origin data type.
2622 @node package Reference
2623 @subsection @code{package} Reference
2625 This section summarizes all the options available in @code{package}
2626 declarations (@pxref{Defining Packages}).
2628 @deftp {Data Type} package
2629 This is the data type representing a package recipe.
2633 The name of the package, as a string.
2635 @item @code{version}
2636 The version of the package, as a string.
2639 An object telling how the source code for the package should be
2640 acquired. Most of the time, this is an @code{origin} object, which
2641 denotes a file fetched from the Internet (@pxref{origin Reference}). It
2642 can also be any other ``file-like'' object such as a @code{local-file},
2643 which denotes a file from the local file system (@pxref{G-Expressions,
2644 @code{local-file}}).
2646 @item @code{build-system}
2647 The build system that should be used to build the package (@pxref{Build
2650 @item @code{arguments} (default: @code{'()})
2651 The arguments that should be passed to the build system. This is a
2652 list, typically containing sequential keyword-value pairs.
2654 @item @code{inputs} (default: @code{'()})
2655 @itemx @code{native-inputs} (default: @code{'()})
2656 @itemx @code{propagated-inputs} (default: @code{'()})
2657 @cindex inputs, of packages
2658 These fields list dependencies of the package. Each one is a list of
2659 tuples, where each tuple has a label for the input (a string) as its
2660 first element, a package, origin, or derivation as its second element,
2661 and optionally the name of the output thereof that should be used, which
2662 defaults to @code{"out"} (@pxref{Packages with Multiple Outputs}, for
2663 more on package outputs). For example, the list below specifies three
2667 `(("libffi" ,libffi)
2668 ("libunistring" ,libunistring)
2669 ("glib:bin" ,glib "bin")) ;the "bin" output of Glib
2672 @cindex cross compilation, package dependencies
2673 The distinction between @code{native-inputs} and @code{inputs} is
2674 necessary when considering cross-compilation. When cross-compiling,
2675 dependencies listed in @code{inputs} are built for the @emph{target}
2676 architecture; conversely, dependencies listed in @code{native-inputs}
2677 are built for the architecture of the @emph{build} machine.
2679 @code{native-inputs} is typically used to list tools needed at
2680 build time, but not at run time, such as Autoconf, Automake, pkg-config,
2681 Gettext, or Bison. @command{guix lint} can report likely mistakes in
2682 this area (@pxref{Invoking guix lint}).
2684 @anchor{package-propagated-inputs}
2685 Lastly, @code{propagated-inputs} is similar to @code{inputs}, but the
2686 specified packages will be automatically installed alongside the package
2687 they belong to (@pxref{package-cmd-propagated-inputs, @command{guix
2688 package}}, for information on how @command{guix package} deals with
2691 For example this is necessary when a C/C++ library needs headers of
2692 another library to compile, or when a pkg-config file refers to another
2693 one @i{via} its @code{Requires} field.
2695 Another example where @code{propagated-inputs} is useful is for languages
2696 that lack a facility to record the run-time search path akin to the
2697 @code{RUNPATH} of ELF files; this includes Guile, Python, Perl, GHC, and
2698 more. To ensure that libraries written in those languages can find
2699 library code they depend on at run time, run-time dependencies must be
2700 listed in @code{propagated-inputs} rather than @code{inputs}.
2702 @item @code{self-native-input?} (default: @code{#f})
2703 This is a Boolean field telling whether the package should use itself as
2704 a native input when cross-compiling.
2706 @item @code{outputs} (default: @code{'("out")})
2707 The list of output names of the package. @xref{Packages with Multiple
2708 Outputs}, for typical uses of additional outputs.
2710 @item @code{native-search-paths} (default: @code{'()})
2711 @itemx @code{search-paths} (default: @code{'()})
2712 A list of @code{search-path-specification} objects describing
2713 search-path environment variables honored by the package.
2715 @item @code{replacement} (default: @code{#f})
2716 This must be either @code{#f} or a package object that will be used as a
2717 @dfn{replacement} for this package. @xref{Security Updates, grafts},
2720 @item @code{synopsis}
2721 A one-line description of the package.
2723 @item @code{description}
2724 A more elaborate description of the package.
2726 @item @code{license}
2727 The license of the package; a value from @code{(guix licenses)},
2728 or a list of such values.
2730 @item @code{home-page}
2731 The URL to the home-page of the package, as a string.
2733 @item @code{supported-systems} (default: @var{%supported-systems})
2734 The list of systems supported by the package, as strings of the form
2735 @code{architecture-kernel}, for example @code{"x86_64-linux"}.
2737 @item @code{maintainers} (default: @code{'()})
2738 The list of maintainers of the package, as @code{maintainer} objects.
2740 @item @code{location} (default: source location of the @code{package} form)
2741 The source location of the package. It is useful to override this when
2742 inheriting from another package, in which case this field is not
2743 automatically corrected.
2748 @node origin Reference
2749 @subsection @code{origin} Reference
2751 This section summarizes all the options available in @code{origin}
2752 declarations (@pxref{Defining Packages}).
2754 @deftp {Data Type} origin
2755 This is the data type representing a source code origin.
2759 An object containing the URI of the source. The object type depends on
2760 the @code{method} (see below). For example, when using the
2761 @var{url-fetch} method of @code{(guix download)}, the valid @code{uri}
2762 values are: a URL represented as a string, or a list thereof.
2765 A procedure that handles the URI.
2770 @item @var{url-fetch} from @code{(guix download)}
2771 download a file from the HTTP, HTTPS, or FTP URL specified in the
2775 @item @var{git-fetch} from @code{(guix git-download)}
2776 clone the Git version control repository, and check out the revision
2777 specified in the @code{uri} field as a @code{git-reference} object; a
2778 @code{git-reference} looks like this:
2782 (url "git://git.debian.org/git/pkg-shadow/shadow")
2783 (commit "v4.1.5.1"))
2788 A bytevector containing the SHA-256 hash of the source. Typically the
2789 @code{base32} form is used here to generate the bytevector from a
2792 You can obtain this information using @code{guix download}
2793 (@pxref{Invoking guix download}) or @code{guix hash} (@pxref{Invoking
2796 @item @code{file-name} (default: @code{#f})
2797 The file name under which the source code should be saved. When this is
2798 @code{#f}, a sensible default value will be used in most cases. In case
2799 the source is fetched from a URL, the file name from the URL will be
2800 used. For version control checkouts, it is recommended to provide the
2801 file name explicitly because the default is not very descriptive.
2803 @item @code{patches} (default: @code{'()})
2804 A list of file names containing patches to be applied to the source.
2806 @item @code{snippet} (default: @code{#f})
2807 A G-expression (@pxref{G-Expressions}) or S-expression that will be run
2808 in the source directory. This is a convenient way to modify the source,
2809 sometimes more convenient than a patch.
2811 @item @code{patch-flags} (default: @code{'("-p1")})
2812 A list of command-line flags that should be passed to the @code{patch}
2815 @item @code{patch-inputs} (default: @code{#f})
2816 Input packages or derivations to the patching process. When this is
2817 @code{#f}, the usual set of inputs necessary for patching are provided,
2818 such as GNU@tie{}Patch.
2820 @item @code{modules} (default: @code{'()})
2821 A list of Guile modules that should be loaded during the patching
2822 process and while running the code in the @code{snippet} field.
2824 @item @code{patch-guile} (default: @code{#f})
2825 The Guile package that should be used in the patching process. When
2826 this is @code{#f}, a sensible default is used.
2832 @section Build Systems
2834 @cindex build system
2835 Each package definition specifies a @dfn{build system} and arguments for
2836 that build system (@pxref{Defining Packages}). This @code{build-system}
2837 field represents the build procedure of the package, as well as implicit
2838 dependencies of that build procedure.
2840 Build systems are @code{<build-system>} objects. The interface to
2841 create and manipulate them is provided by the @code{(guix build-system)}
2842 module, and actual build systems are exported by specific modules.
2844 @cindex bag (low-level package representation)
2845 Under the hood, build systems first compile package objects to
2846 @dfn{bags}. A @dfn{bag} is like a package, but with less
2847 ornamentation---in other words, a bag is a lower-level representation of
2848 a package, which includes all the inputs of that package, including some
2849 that were implicitly added by the build system. This intermediate
2850 representation is then compiled to a derivation (@pxref{Derivations}).
2852 Build systems accept an optional list of @dfn{arguments}. In package
2853 definitions, these are passed @i{via} the @code{arguments} field
2854 (@pxref{Defining Packages}). They are typically keyword arguments
2855 (@pxref{Optional Arguments, keyword arguments in Guile,, guile, GNU
2856 Guile Reference Manual}). The value of these arguments is usually
2857 evaluated in the @dfn{build stratum}---i.e., by a Guile process launched
2858 by the daemon (@pxref{Derivations}).
2860 The main build system is @var{gnu-build-system}, which implements the
2861 standard build procedure for GNU and many other packages. It
2862 is provided by the @code{(guix build-system gnu)} module.
2864 @defvr {Scheme Variable} gnu-build-system
2865 @var{gnu-build-system} represents the GNU Build System, and variants
2866 thereof (@pxref{Configuration, configuration and makefile conventions,,
2867 standards, GNU Coding Standards}).
2869 @cindex build phases
2870 In a nutshell, packages using it are configured, built, and installed with
2871 the usual @code{./configure && make && make check && make install}
2872 command sequence. In practice, a few additional steps are often needed.
2873 All these steps are split up in separate @dfn{phases},
2874 notably@footnote{Please see the @code{(guix build gnu-build-system)}
2875 modules for more details about the build phases.}:
2879 Unpack the source tarball, and change the current directory to the
2880 extracted source tree. If the source is actually a directory, copy it
2881 to the build tree, and enter that directory.
2883 @item patch-source-shebangs
2884 Patch shebangs encountered in source files so they refer to the right
2885 store file names. For instance, this changes @code{#!/bin/sh} to
2886 @code{#!/gnu/store/@dots{}-bash-4.3/bin/sh}.
2889 Run the @file{configure} script with a number of default options, such
2890 as @code{--prefix=/gnu/store/@dots{}}, as well as the options specified
2891 by the @code{#:configure-flags} argument.
2894 Run @code{make} with the list of flags specified with
2895 @code{#:make-flags}. If the @code{#:parallel-build?} argument is true
2896 (the default), build with @code{make -j}.
2899 Run @code{make check}, or some other target specified with
2900 @code{#:test-target}, unless @code{#:tests? #f} is passed. If the
2901 @code{#:parallel-tests?} argument is true (the default), run @code{make
2905 Run @code{make install} with the flags listed in @code{#:make-flags}.
2907 @item patch-shebangs
2908 Patch shebangs on the installed executable files.
2911 Strip debugging symbols from ELF files (unless @code{#:strip-binaries?}
2912 is false), copying them to the @code{debug} output when available
2913 (@pxref{Installing Debugging Files}).
2916 @vindex %standard-phases
2917 The build-side module @code{(guix build gnu-build-system)} defines
2918 @var{%standard-phases} as the default list of build phases.
2919 @var{%standard-phases} is a list of symbol/procedure pairs, where the
2920 procedure implements the actual phase.
2922 The list of phases used for a particular package can be changed with the
2923 @code{#:phases} parameter. For instance, passing:
2926 #:phases (modify-phases %standard-phases (delete 'configure))
2929 means that all the phases described above will be used, except the
2930 @code{configure} phase.
2932 In addition, this build system ensures that the ``standard'' environment
2933 for GNU packages is available. This includes tools such as GCC, libc,
2934 Coreutils, Bash, Make, Diffutils, grep, and sed (see the @code{(guix
2935 build-system gnu)} module for a complete list). We call these the
2936 @dfn{implicit inputs} of a package, because package definitions do not
2937 have to mention them.
2940 Other @code{<build-system>} objects are defined to support other
2941 conventions and tools used by free software packages. They inherit most
2942 of @var{gnu-build-system}, and differ mainly in the set of inputs
2943 implicitly added to the build process, and in the list of phases
2944 executed. Some of these build systems are listed below.
2946 @defvr {Scheme Variable} ant-build-system
2947 This variable is exported by @code{(guix build-system ant)}. It
2948 implements the build procedure for Java packages that can be built with
2949 @url{http://ant.apache.org/, Ant build tool}.
2951 It adds both @code{ant} and the @dfn{Java Development Kit} (JDK) as
2952 provided by the @code{icedtea} package to the set of inputs. Different
2953 packages can be specified with the @code{#:ant} and @code{#:jdk}
2954 parameters, respectively.
2956 When the original package does not provide a suitable Ant build file,
2957 the parameter @code{#:jar-name} can be used to generate a minimal Ant
2958 build file @file{build.xml} with tasks to build the specified jar
2961 The parameter @code{#:build-target} can be used to specify the Ant task
2962 that should be run during the @code{build} phase. By default the
2963 ``jar'' task will be run.
2967 @defvr {Scheme Variable} cmake-build-system
2968 This variable is exported by @code{(guix build-system cmake)}. It
2969 implements the build procedure for packages using the
2970 @url{http://www.cmake.org, CMake build tool}.
2972 It automatically adds the @code{cmake} package to the set of inputs.
2973 Which package is used can be specified with the @code{#:cmake}
2976 The @code{#:configure-flags} parameter is taken as a list of flags
2977 passed to the @command{cmake} command. The @code{#:build-type}
2978 parameter specifies in abstract terms the flags passed to the compiler;
2979 it defaults to @code{"RelWithDebInfo"} (short for ``release mode with
2980 debugging information''), which roughly means that code is compiled with
2981 @code{-O2 -g}, as is the case for Autoconf-based packages by default.
2984 @defvr {Scheme Variable} glib-or-gtk-build-system
2985 This variable is exported by @code{(guix build-system glib-or-gtk)}. It
2986 is intended for use with packages making use of GLib or GTK+.
2988 This build system adds the following two phases to the ones defined by
2989 @var{gnu-build-system}:
2992 @item glib-or-gtk-wrap
2993 The phase @code{glib-or-gtk-wrap} ensures that programs in
2994 @file{bin/} are able to find GLib ``schemas'' and
2995 @uref{https://developer.gnome.org/gtk3/stable/gtk-running.html, GTK+
2996 modules}. This is achieved by wrapping the programs in launch scripts
2997 that appropriately set the @code{XDG_DATA_DIRS} and @code{GTK_PATH}
2998 environment variables.
3000 It is possible to exclude specific package outputs from that wrapping
3001 process by listing their names in the
3002 @code{#:glib-or-gtk-wrap-excluded-outputs} parameter. This is useful
3003 when an output is known not to contain any GLib or GTK+ binaries, and
3004 where wrapping would gratuitously add a dependency of that output on
3007 @item glib-or-gtk-compile-schemas
3008 The phase @code{glib-or-gtk-compile-schemas} makes sure that all
3009 @uref{https://developer.gnome.org/gio/stable/glib-compile-schemas.html,
3010 GSettings schemas} of GLib are compiled. Compilation is performed by the
3011 @command{glib-compile-schemas} program. It is provided by the package
3012 @code{glib:bin} which is automatically imported by the build system.
3013 The @code{glib} package providing @command{glib-compile-schemas} can be
3014 specified with the @code{#:glib} parameter.
3017 Both phases are executed after the @code{install} phase.
3020 @defvr {Scheme Variable} python-build-system
3021 This variable is exported by @code{(guix build-system python)}. It
3022 implements the more or less standard build procedure used by Python
3023 packages, which consists in running @code{python setup.py build} and
3024 then @code{python setup.py install --prefix=/gnu/store/@dots{}}.
3026 For packages that install stand-alone Python programs under @code{bin/},
3027 it takes care of wrapping these programs so that their @code{PYTHONPATH}
3028 environment variable points to all the Python libraries they depend on.
3030 Which Python package is used to perform the build can be specified with
3031 the @code{#:python} parameter. This is a useful way to force a package
3032 to be built for a specific version of the Python interpreter, which
3033 might be necessary if the package is only compatible with a single
3034 interpreter version.
3037 @defvr {Scheme Variable} perl-build-system
3038 This variable is exported by @code{(guix build-system perl)}. It
3039 implements the standard build procedure for Perl packages, which either
3040 consists in running @code{perl Build.PL --prefix=/gnu/store/@dots{}},
3041 followed by @code{Build} and @code{Build install}; or in running
3042 @code{perl Makefile.PL PREFIX=/gnu/store/@dots{}}, followed by
3043 @code{make} and @code{make install}, depending on which of
3044 @code{Build.PL} or @code{Makefile.PL} is present in the package
3045 distribution. Preference is given to the former if both @code{Build.PL}
3046 and @code{Makefile.PL} exist in the package distribution. This
3047 preference can be reversed by specifying @code{#t} for the
3048 @code{#:make-maker?} parameter.
3050 The initial @code{perl Makefile.PL} or @code{perl Build.PL} invocation
3051 passes flags specified by the @code{#:make-maker-flags} or
3052 @code{#:module-build-flags} parameter, respectively.
3054 Which Perl package is used can be specified with @code{#:perl}.
3057 @defvr {Scheme Variable} r-build-system
3058 This variable is exported by @code{(guix build-system r)}. It
3059 implements the build procedure used by @uref{http://r-project.org, R}
3060 packages, which essentially is little more than running @code{R CMD
3061 INSTALL --library=/gnu/store/@dots{}} in an environment where
3062 @code{R_LIBS_SITE} contains the paths to all R package inputs. Tests
3063 are run after installation using the R function
3064 @code{tools::testInstalledPackage}.
3067 @defvr {Scheme Variable} ruby-build-system
3068 This variable is exported by @code{(guix build-system ruby)}. It
3069 implements the RubyGems build procedure used by Ruby packages, which
3070 involves running @code{gem build} followed by @code{gem install}.
3072 The @code{source} field of a package that uses this build system
3073 typically references a gem archive, since this is the format that Ruby
3074 developers use when releasing their software. The build system unpacks
3075 the gem archive, potentially patches the source, runs the test suite,
3076 repackages the gem, and installs it. Additionally, directories and
3077 tarballs may be referenced to allow building unreleased gems from Git or
3078 a traditional source release tarball.
3080 Which Ruby package is used can be specified with the @code{#:ruby}
3081 parameter. A list of additional flags to be passed to the @command{gem}
3082 command can be specified with the @code{#:gem-flags} parameter.
3085 @defvr {Scheme Variable} waf-build-system
3086 This variable is exported by @code{(guix build-system waf)}. It
3087 implements a build procedure around the @code{waf} script. The common
3088 phases---@code{configure}, @code{build}, and @code{install}---are
3089 implemented by passing their names as arguments to the @code{waf}
3092 The @code{waf} script is executed by the Python interpreter. Which
3093 Python package is used to run the script can be specified with the
3094 @code{#:python} parameter.
3097 @defvr {Scheme Variable} haskell-build-system
3098 This variable is exported by @code{(guix build-system haskell)}. It
3099 implements the Cabal build procedure used by Haskell packages, which
3100 involves running @code{runhaskell Setup.hs configure
3101 --prefix=/gnu/store/@dots{}} and @code{runhaskell Setup.hs build}.
3102 Instead of installing the package by running @code{runhaskell Setup.hs
3103 install}, to avoid trying to register libraries in the read-only
3104 compiler store directory, the build system uses @code{runhaskell
3105 Setup.hs copy}, followed by @code{runhaskell Setup.hs register}. In
3106 addition, the build system generates the package documentation by
3107 running @code{runhaskell Setup.hs haddock}, unless @code{#:haddock? #f}
3108 is passed. Optional Haddock parameters can be passed with the help of
3109 the @code{#:haddock-flags} parameter. If the file @code{Setup.hs} is
3110 not found, the build system looks for @code{Setup.lhs} instead.
3112 Which Haskell compiler is used can be specified with the @code{#:haskell}
3113 parameter which defaults to @code{ghc}.
3116 @defvr {Scheme Variable} emacs-build-system
3117 This variable is exported by @code{(guix build-system emacs)}. It
3118 implements an installation procedure similar to the packaging system
3119 of Emacs itself (@pxref{Packages,,, emacs, The GNU Emacs Manual}).
3121 It first creates the @code{@var{package}-autoloads.el} file, then it
3122 byte compiles all Emacs Lisp files. Differently from the Emacs
3123 packaging system, the Info documentation files are moved to the standard
3124 documentation directory and the @file{dir} file is deleted. Each
3125 package is installed in its own directory under
3126 @file{share/emacs/site-lisp/guix.d}.
3129 Lastly, for packages that do not need anything as sophisticated, a
3130 ``trivial'' build system is provided. It is trivial in the sense that
3131 it provides basically no support: it does not pull any implicit inputs,
3132 and does not have a notion of build phases.
3134 @defvr {Scheme Variable} trivial-build-system
3135 This variable is exported by @code{(guix build-system trivial)}.
3137 This build system requires a @code{#:builder} argument. This argument
3138 must be a Scheme expression that builds the package output(s)---as
3139 with @code{build-expression->derivation} (@pxref{Derivations,
3140 @code{build-expression->derivation}}).
3150 Conceptually, the @dfn{store} is the place where derivations that have
3151 been built successfully are stored---by default, @file{/gnu/store}.
3152 Sub-directories in the store are referred to as @dfn{store items} or
3153 sometimes @dfn{store paths}. The store has an associated database that
3154 contains information such as the store paths referred to by each store
3155 path, and the list of @emph{valid} store items---results of successful
3156 builds. This database resides in @file{@var{localstatedir}/guix/db},
3157 where @var{localstatedir} is the state directory specified @i{via}
3158 @option{--localstatedir} at configure time, usually @file{/var}.
3160 The store is @emph{always} accessed by the daemon on behalf of its clients
3161 (@pxref{Invoking guix-daemon}). To manipulate the store, clients
3162 connect to the daemon over a Unix-domain socket, send requests to it,
3163 and read the result---these are remote procedure calls, or RPCs.
3166 Users must @emph{never} modify files under @file{/gnu/store} directly.
3167 This would lead to inconsistencies and break the immutability
3168 assumptions of Guix's functional model (@pxref{Introduction}).
3170 @xref{Invoking guix gc, @command{guix gc --verify}}, for information on
3171 how to check the integrity of the store and attempt recovery from
3172 accidental modifications.
3175 The @code{(guix store)} module provides procedures to connect to the
3176 daemon, and to perform RPCs. These are described below.
3178 @deffn {Scheme Procedure} open-connection [@var{file}] [#:reserve-space? #t]
3179 Connect to the daemon over the Unix-domain socket at @var{file}. When
3180 @var{reserve-space?} is true, instruct it to reserve a little bit of
3181 extra space on the file system so that the garbage collector can still
3182 operate should the disk become full. Return a server object.
3184 @var{file} defaults to @var{%default-socket-path}, which is the normal
3185 location given the options that were passed to @command{configure}.
3188 @deffn {Scheme Procedure} close-connection @var{server}
3189 Close the connection to @var{server}.
3192 @defvr {Scheme Variable} current-build-output-port
3193 This variable is bound to a SRFI-39 parameter, which refers to the port
3194 where build and error logs sent by the daemon should be written.
3197 Procedures that make RPCs all take a server object as their first
3200 @deffn {Scheme Procedure} valid-path? @var{server} @var{path}
3201 @cindex invalid store items
3202 Return @code{#t} when @var{path} designates a valid store item and
3203 @code{#f} otherwise (an invalid item may exist on disk but still be
3204 invalid, for instance because it is the result of an aborted or failed
3207 A @code{&nix-protocol-error} condition is raised if @var{path} is not
3208 prefixed by the store directory (@file{/gnu/store}).
3211 @deffn {Scheme Procedure} add-text-to-store @var{server} @var{name} @var{text} [@var{references}]
3212 Add @var{text} under file @var{name} in the store, and return its store
3213 path. @var{references} is the list of store paths referred to by the
3214 resulting store path.
3217 @deffn {Scheme Procedure} build-derivations @var{server} @var{derivations}
3218 Build @var{derivations} (a list of @code{<derivation>} objects or
3219 derivation paths), and return when the worker is done building them.
3220 Return @code{#t} on success.
3223 Note that the @code{(guix monads)} module provides a monad as well as
3224 monadic versions of the above procedures, with the goal of making it
3225 more convenient to work with code that accesses the store (@pxref{The
3229 @i{This section is currently incomplete.}
3232 @section Derivations
3235 Low-level build actions and the environment in which they are performed
3236 are represented by @dfn{derivations}. A derivation contains the
3237 following pieces of information:
3241 The outputs of the derivation---derivations produce at least one file or
3242 directory in the store, but may produce more.
3245 The inputs of the derivations, which may be other derivations or plain
3246 files in the store (patches, build scripts, etc.)
3249 The system type targeted by the derivation---e.g., @code{x86_64-linux}.
3252 The file name of a build script in the store, along with the arguments
3256 A list of environment variables to be defined.
3260 @cindex derivation path
3261 Derivations allow clients of the daemon to communicate build actions to
3262 the store. They exist in two forms: as an in-memory representation,
3263 both on the client- and daemon-side, and as files in the store whose
3264 name end in @code{.drv}---these files are referred to as @dfn{derivation
3265 paths}. Derivations paths can be passed to the @code{build-derivations}
3266 procedure to perform the build actions they prescribe (@pxref{The
3269 The @code{(guix derivations)} module provides a representation of
3270 derivations as Scheme objects, along with procedures to create and
3271 otherwise manipulate derivations. The lowest-level primitive to create
3272 a derivation is the @code{derivation} procedure:
3274 @deffn {Scheme Procedure} derivation @var{store} @var{name} @var{builder} @
3275 @var{args} [#:outputs '("out")] [#:hash #f] [#:hash-algo #f] @
3276 [#:recursive? #f] [#:inputs '()] [#:env-vars '()] @
3277 [#:system (%current-system)] [#:references-graphs #f] @
3278 [#:allowed-references #f] [#:disallowed-references #f] @
3279 [#:leaked-env-vars #f] [#:local-build? #f] @
3280 [#:substitutable? #t]
3281 Build a derivation with the given arguments, and return the resulting
3282 @code{<derivation>} object.
3284 When @var{hash} and @var{hash-algo} are given, a
3285 @dfn{fixed-output derivation} is created---i.e., one whose result is
3286 known in advance, such as a file download. If, in addition,
3287 @var{recursive?} is true, then that fixed output may be an executable
3288 file or a directory and @var{hash} must be the hash of an archive
3289 containing this output.
3291 When @var{references-graphs} is true, it must be a list of file
3292 name/store path pairs. In that case, the reference graph of each store
3293 path is exported in the build environment in the corresponding file, in
3294 a simple text format.
3296 When @var{allowed-references} is true, it must be a list of store items
3297 or outputs that the derivation's output may refer to. Likewise,
3298 @var{disallowed-references}, if true, must be a list of things the
3299 outputs may @emph{not} refer to.
3301 When @var{leaked-env-vars} is true, it must be a list of strings
3302 denoting environment variables that are allowed to ``leak'' from the
3303 daemon's environment to the build environment. This is only applicable
3304 to fixed-output derivations---i.e., when @var{hash} is true. The main
3305 use is to allow variables such as @code{http_proxy} to be passed to
3306 derivations that download files.
3308 When @var{local-build?} is true, declare that the derivation is not a
3309 good candidate for offloading and should rather be built locally
3310 (@pxref{Daemon Offload Setup}). This is the case for small derivations
3311 where the costs of data transfers would outweigh the benefits.
3313 When @var{substitutable?} is false, declare that substitutes of the
3314 derivation's output should not be used (@pxref{Substitutes}). This is
3315 useful, for instance, when building packages that capture details of the
3316 host CPU instruction set.
3320 Here's an example with a shell script as its builder, assuming
3321 @var{store} is an open connection to the daemon, and @var{bash} points
3322 to a Bash executable in the store:
3325 (use-modules (guix utils)
3329 (let ((builder ; add the Bash script to the store
3330 (add-text-to-store store "my-builder.sh"
3331 "echo hello world > $out\n" '())))
3332 (derivation store "foo"
3333 bash `("-e" ,builder)
3334 #:inputs `((,bash) (,builder))
3335 #:env-vars '(("HOME" . "/homeless"))))
3336 @result{} #<derivation /gnu/store/@dots{}-foo.drv => /gnu/store/@dots{}-foo>
3339 As can be guessed, this primitive is cumbersome to use directly. A
3340 better approach is to write build scripts in Scheme, of course! The
3341 best course of action for that is to write the build code as a
3342 ``G-expression'', and to pass it to @code{gexp->derivation}. For more
3343 information, @pxref{G-Expressions}.
3345 Once upon a time, @code{gexp->derivation} did not exist and constructing
3346 derivations with build code written in Scheme was achieved with
3347 @code{build-expression->derivation}, documented below. This procedure
3348 is now deprecated in favor of the much nicer @code{gexp->derivation}.
3350 @deffn {Scheme Procedure} build-expression->derivation @var{store} @
3351 @var{name} @var{exp} @
3352 [#:system (%current-system)] [#:inputs '()] @
3353 [#:outputs '("out")] [#:hash #f] [#:hash-algo #f] @
3354 [#:recursive? #f] [#:env-vars '()] [#:modules '()] @
3355 [#:references-graphs #f] [#:allowed-references #f] @
3356 [#:disallowed-references #f] @
3357 [#:local-build? #f] [#:substitutable? #t] [#:guile-for-build #f]
3358 Return a derivation that executes Scheme expression @var{exp} as a
3359 builder for derivation @var{name}. @var{inputs} must be a list of
3360 @code{(name drv-path sub-drv)} tuples; when @var{sub-drv} is omitted,
3361 @code{"out"} is assumed. @var{modules} is a list of names of Guile
3362 modules from the current search path to be copied in the store,
3363 compiled, and made available in the load path during the execution of
3364 @var{exp}---e.g., @code{((guix build utils) (guix build
3365 gnu-build-system))}.
3367 @var{exp} is evaluated in an environment where @code{%outputs} is bound
3368 to a list of output/path pairs, and where @code{%build-inputs} is bound
3369 to a list of string/output-path pairs made from @var{inputs}.
3370 Optionally, @var{env-vars} is a list of string pairs specifying the name
3371 and value of environment variables visible to the builder. The builder
3372 terminates by passing the result of @var{exp} to @code{exit}; thus, when
3373 @var{exp} returns @code{#f}, the build is considered to have failed.
3375 @var{exp} is built using @var{guile-for-build} (a derivation). When
3376 @var{guile-for-build} is omitted or is @code{#f}, the value of the
3377 @code{%guile-for-build} fluid is used instead.
3379 See the @code{derivation} procedure for the meaning of
3380 @var{references-graphs}, @var{allowed-references},
3381 @var{disallowed-references}, @var{local-build?}, and
3382 @var{substitutable?}.
3386 Here's an example of a single-output derivation that creates a directory
3387 containing one file:
3390 (let ((builder '(let ((out (assoc-ref %outputs "out")))
3391 (mkdir out) ; create /gnu/store/@dots{}-goo
3392 (call-with-output-file (string-append out "/test")
3394 (display '(hello guix) p))))))
3395 (build-expression->derivation store "goo" builder))
3397 @result{} #<derivation /gnu/store/@dots{}-goo.drv => @dots{}>
3401 @node The Store Monad
3402 @section The Store Monad
3406 The procedures that operate on the store described in the previous
3407 sections all take an open connection to the build daemon as their first
3408 argument. Although the underlying model is functional, they either have
3409 side effects or depend on the current state of the store.
3411 The former is inconvenient: the connection to the build daemon has to be
3412 carried around in all those functions, making it impossible to compose
3413 functions that do not take that parameter with functions that do. The
3414 latter can be problematic: since store operations have side effects
3415 and/or depend on external state, they have to be properly sequenced.
3417 @cindex monadic values
3418 @cindex monadic functions
3419 This is where the @code{(guix monads)} module comes in. This module
3420 provides a framework for working with @dfn{monads}, and a particularly
3421 useful monad for our uses, the @dfn{store monad}. Monads are a
3422 construct that allows two things: associating ``context'' with values
3423 (in our case, the context is the store), and building sequences of
3424 computations (here computations include accesses to the store). Values
3425 in a monad---values that carry this additional context---are called
3426 @dfn{monadic values}; procedures that return such values are called
3427 @dfn{monadic procedures}.
3429 Consider this ``normal'' procedure:
3432 (define (sh-symlink store)
3433 ;; Return a derivation that symlinks the 'bash' executable.
3434 (let* ((drv (package-derivation store bash))
3435 (out (derivation->output-path drv))
3436 (sh (string-append out "/bin/bash")))
3437 (build-expression->derivation store "sh"
3438 `(symlink ,sh %output))))
3441 Using @code{(guix monads)} and @code{(guix gexp)}, it may be rewritten
3442 as a monadic function:
3445 (define (sh-symlink)
3446 ;; Same, but return a monadic value.
3447 (mlet %store-monad ((drv (package->derivation bash)))
3448 (gexp->derivation "sh"
3449 #~(symlink (string-append #$drv "/bin/bash")
3453 There are several things to note in the second version: the @code{store}
3454 parameter is now implicit and is ``threaded'' in the calls to the
3455 @code{package->derivation} and @code{gexp->derivation} monadic
3456 procedures, and the monadic value returned by @code{package->derivation}
3457 is @dfn{bound} using @code{mlet} instead of plain @code{let}.
3459 As it turns out, the call to @code{package->derivation} can even be
3460 omitted since it will take place implicitly, as we will see later
3461 (@pxref{G-Expressions}):
3464 (define (sh-symlink)
3465 (gexp->derivation "sh"
3466 #~(symlink (string-append #$bash "/bin/bash")
3471 @c <https://syntaxexclamation.wordpress.com/2014/06/26/escaping-continuations/>
3472 @c for the funny quote.
3473 Calling the monadic @code{sh-symlink} has no effect. As someone once
3474 said, ``you exit a monad like you exit a building on fire: by running''.
3475 So, to exit the monad and get the desired effect, one must use
3476 @code{run-with-store}:
3479 (run-with-store (open-connection) (sh-symlink))
3480 @result{} /gnu/store/...-sh-symlink
3483 Note that the @code{(guix monad-repl)} module extends the Guile REPL with
3484 new ``meta-commands'' to make it easier to deal with monadic procedures:
3485 @code{run-in-store}, and @code{enter-store-monad}. The former is used
3486 to ``run'' a single monadic value through the store:
3489 scheme@@(guile-user)> ,run-in-store (package->derivation hello)
3490 $1 = #<derivation /gnu/store/@dots{}-hello-2.9.drv => @dots{}>
3493 The latter enters a recursive REPL, where all the return values are
3494 automatically run through the store:
3497 scheme@@(guile-user)> ,enter-store-monad
3498 store-monad@@(guile-user) [1]> (package->derivation hello)
3499 $2 = #<derivation /gnu/store/@dots{}-hello-2.9.drv => @dots{}>
3500 store-monad@@(guile-user) [1]> (text-file "foo" "Hello!")
3501 $3 = "/gnu/store/@dots{}-foo"
3502 store-monad@@(guile-user) [1]> ,q
3503 scheme@@(guile-user)>
3507 Note that non-monadic values cannot be returned in the
3508 @code{store-monad} REPL.
3510 The main syntactic forms to deal with monads in general are provided by
3511 the @code{(guix monads)} module and are described below.
3513 @deffn {Scheme Syntax} with-monad @var{monad} @var{body} ...
3514 Evaluate any @code{>>=} or @code{return} forms in @var{body} as being
3518 @deffn {Scheme Syntax} return @var{val}
3519 Return a monadic value that encapsulates @var{val}.
3522 @deffn {Scheme Syntax} >>= @var{mval} @var{mproc} ...
3523 @dfn{Bind} monadic value @var{mval}, passing its ``contents'' to monadic
3524 procedures @var{mproc}@dots{}@footnote{This operation is commonly
3525 referred to as ``bind'', but that name denotes an unrelated procedure in
3526 Guile. Thus we use this somewhat cryptic symbol inherited from the
3527 Haskell language.}. There can be one @var{mproc} or several of them, as
3532 (with-monad %state-monad
3534 (lambda (x) (return (+ 1 x)))
3535 (lambda (x) (return (* 2 x)))))
3539 @result{} some-state
3543 @deffn {Scheme Syntax} mlet @var{monad} ((@var{var} @var{mval}) ...) @
3545 @deffnx {Scheme Syntax} mlet* @var{monad} ((@var{var} @var{mval}) ...) @
3547 Bind the variables @var{var} to the monadic values @var{mval} in
3548 @var{body}. The form (@var{var} -> @var{val}) binds @var{var} to the
3549 ``normal'' value @var{val}, as per @code{let}.
3551 @code{mlet*} is to @code{mlet} what @code{let*} is to @code{let}
3552 (@pxref{Local Bindings,,, guile, GNU Guile Reference Manual}).
3555 @deffn {Scheme System} mbegin @var{monad} @var{mexp} ...
3556 Bind @var{mexp} and the following monadic expressions in sequence,
3557 returning the result of the last expression.
3559 This is akin to @code{mlet}, except that the return values of the
3560 monadic expressions are ignored. In that sense, it is analogous to
3561 @code{begin}, but applied to monadic expressions.
3565 The @code{(guix monads)} module provides the @dfn{state monad}, which
3566 allows an additional value---the state---to be @emph{threaded} through
3567 monadic procedure calls.
3569 @defvr {Scheme Variable} %state-monad
3570 The state monad. Procedures in the state monad can access and change
3571 the state that is threaded.
3573 Consider the example below. The @code{square} procedure returns a value
3574 in the state monad. It returns the square of its argument, but also
3575 increments the current state value:
3579 (mlet %state-monad ((count (current-state)))
3580 (mbegin %state-monad
3581 (set-current-state (+ 1 count))
3584 (run-with-state (sequence %state-monad (map square (iota 3))) 0)
3589 When ``run'' through @var{%state-monad}, we obtain that additional state
3590 value, which is the number of @code{square} calls.
3593 @deffn {Monadic Procedure} current-state
3594 Return the current state as a monadic value.
3597 @deffn {Monadic Procedure} set-current-state @var{value}
3598 Set the current state to @var{value} and return the previous state as a
3602 @deffn {Monadic Procedure} state-push @var{value}
3603 Push @var{value} to the current state, which is assumed to be a list,
3604 and return the previous state as a monadic value.
3607 @deffn {Monadic Procedure} state-pop
3608 Pop a value from the current state and return it as a monadic value.
3609 The state is assumed to be a list.
3612 @deffn {Scheme Procedure} run-with-state @var{mval} [@var{state}]
3613 Run monadic value @var{mval} starting with @var{state} as the initial
3614 state. Return two values: the resulting value, and the resulting state.
3617 The main interface to the store monad, provided by the @code{(guix
3618 store)} module, is as follows.
3620 @defvr {Scheme Variable} %store-monad
3621 The store monad---an alias for @var{%state-monad}.
3623 Values in the store monad encapsulate accesses to the store. When its
3624 effect is needed, a value of the store monad must be ``evaluated'' by
3625 passing it to the @code{run-with-store} procedure (see below.)
3628 @deffn {Scheme Procedure} run-with-store @var{store} @var{mval} [#:guile-for-build] [#:system (%current-system)]
3629 Run @var{mval}, a monadic value in the store monad, in @var{store}, an
3630 open store connection.
3633 @deffn {Monadic Procedure} text-file @var{name} @var{text} [@var{references}]
3634 Return as a monadic value the absolute file name in the store of the file
3635 containing @var{text}, a string. @var{references} is a list of store items that the
3636 resulting text file refers to; it defaults to the empty list.
3639 @deffn {Monadic Procedure} interned-file @var{file} [@var{name}] @
3640 [#:recursive? #t] [#:select? (const #t)]
3641 Return the name of @var{file} once interned in the store. Use
3642 @var{name} as its store name, or the basename of @var{file} if
3643 @var{name} is omitted.
3645 When @var{recursive?} is true, the contents of @var{file} are added
3646 recursively; if @var{file} designates a flat file and @var{recursive?}
3647 is true, its contents are added, and its permission bits are kept.
3649 When @var{recursive?} is true, call @code{(@var{select?} @var{file}
3650 @var{stat})} for each directory entry, where @var{file} is the entry's
3651 absolute file name and @var{stat} is the result of @code{lstat}; exclude
3652 entries for which @var{select?} does not return true.
3654 The example below adds a file to the store, under two different names:
3657 (run-with-store (open-connection)
3658 (mlet %store-monad ((a (interned-file "README"))
3659 (b (interned-file "README" "LEGU-MIN")))
3660 (return (list a b))))
3662 @result{} ("/gnu/store/rwm@dots{}-README" "/gnu/store/44i@dots{}-LEGU-MIN")
3667 The @code{(guix packages)} module exports the following package-related
3670 @deffn {Monadic Procedure} package-file @var{package} [@var{file}] @
3671 [#:system (%current-system)] [#:target #f] @
3674 value in the absolute file name of @var{file} within the @var{output}
3675 directory of @var{package}. When @var{file} is omitted, return the name
3676 of the @var{output} directory of @var{package}. When @var{target} is
3677 true, use it as a cross-compilation target triplet.
3680 @deffn {Monadic Procedure} package->derivation @var{package} [@var{system}]
3681 @deffnx {Monadic Procedure} package->cross-derivation @var{package} @
3682 @var{target} [@var{system}]
3683 Monadic version of @code{package-derivation} and
3684 @code{package-cross-derivation} (@pxref{Defining Packages}).
3689 @section G-Expressions
3691 @cindex G-expression
3692 @cindex build code quoting
3693 So we have ``derivations'', which represent a sequence of build actions
3694 to be performed to produce an item in the store (@pxref{Derivations}).
3695 These build actions are performed when asking the daemon to actually
3696 build the derivations; they are run by the daemon in a container
3697 (@pxref{Invoking guix-daemon}).
3699 @cindex strata of code
3700 It should come as no surprise that we like to write these build actions
3701 in Scheme. When we do that, we end up with two @dfn{strata} of Scheme
3702 code@footnote{The term @dfn{stratum} in this context was coined by
3703 Manuel Serrano et al.@: in the context of their work on Hop. Oleg
3704 Kiselyov, who has written insightful
3705 @url{http://okmij.org/ftp/meta-programming/#meta-scheme, essays and code
3706 on this topic}, refers to this kind of code generation as
3707 @dfn{staging}.}: the ``host code''---code that defines packages, talks
3708 to the daemon, etc.---and the ``build code''---code that actually
3709 performs build actions, such as making directories, invoking
3710 @command{make}, etc.
3712 To describe a derivation and its build actions, one typically needs to
3713 embed build code inside host code. It boils down to manipulating build
3714 code as data, and the homoiconicity of Scheme---code has a direct
3715 representation as data---comes in handy for that. But we need more than
3716 the normal @code{quasiquote} mechanism in Scheme to construct build
3719 The @code{(guix gexp)} module implements @dfn{G-expressions}, a form of
3720 S-expressions adapted to build expressions. G-expressions, or
3721 @dfn{gexps}, consist essentially of three syntactic forms: @code{gexp},
3722 @code{ungexp}, and @code{ungexp-splicing} (or simply: @code{#~},
3723 @code{#$}, and @code{#$@@}), which are comparable to
3724 @code{quasiquote}, @code{unquote}, and @code{unquote-splicing},
3725 respectively (@pxref{Expression Syntax, @code{quasiquote},, guile,
3726 GNU Guile Reference Manual}). However, there are major differences:
3730 Gexps are meant to be written to a file and run or manipulated by other
3734 When a high-level object such as a package or derivation is unquoted
3735 inside a gexp, the result is as if its output file name had been
3739 Gexps carry information about the packages or derivations they refer to,
3740 and these dependencies are automatically added as inputs to the build
3741 processes that use them.
3744 @cindex lowering, of high-level objects in gexps
3745 This mechanism is not limited to package and derivation
3746 objects: @dfn{compilers} able to ``lower'' other high-level objects to
3747 derivations or files in the store can be defined,
3748 such that these objects can also be inserted
3749 into gexps. For example, a useful type of high-level objects that can be
3750 inserted in a gexp is ``file-like objects'', which make it easy to
3751 add files to the store and to refer to them in
3752 derivations and such (see @code{local-file} and @code{plain-file}
3755 To illustrate the idea, here is an example of a gexp:
3762 (symlink (string-append #$coreutils "/bin/ls")
3766 This gexp can be passed to @code{gexp->derivation}; we obtain a
3767 derivation that builds a directory containing exactly one symlink to
3768 @file{/gnu/store/@dots{}-coreutils-8.22/bin/ls}:
3771 (gexp->derivation "the-thing" build-exp)
3774 As one would expect, the @code{"/gnu/store/@dots{}-coreutils-8.22"} string is
3775 substituted to the reference to the @var{coreutils} package in the
3776 actual build code, and @var{coreutils} is automatically made an input to
3777 the derivation. Likewise, @code{#$output} (equivalent to @code{(ungexp
3778 output)}) is replaced by a string containing the directory name of the
3779 output of the derivation.
3781 @cindex cross compilation
3782 In a cross-compilation context, it is useful to distinguish between
3783 references to the @emph{native} build of a package---that can run on the
3784 host---versus references to cross builds of a package. To that end, the
3785 @code{#+} plays the same role as @code{#$}, but is a reference to a
3786 native package build:
3789 (gexp->derivation "vi"
3792 (system* (string-append #+coreutils "/bin/ln")
3794 (string-append #$emacs "/bin/emacs")
3795 (string-append #$output "/bin/vi")))
3796 #:target "mips64el-linux")
3800 In the example above, the native build of @var{coreutils} is used, so
3801 that @command{ln} can actually run on the host; but then the
3802 cross-compiled build of @var{emacs} is referenced.
3804 @cindex imported modules, for gexps
3805 @findex with-imported-modules
3806 Another gexp feature is @dfn{imported modules}: sometimes you want to be
3807 able to use certain Guile modules from the ``host environment'' in the
3808 gexp, so those modules should be imported in the ``build environment''.
3809 The @code{with-imported-modules} form allows you to express that:
3812 (let ((build (with-imported-modules '((guix build utils))
3814 (use-modules (guix build utils))
3815 (mkdir-p (string-append #$output "/bin"))))))
3816 (gexp->derivation "empty-dir"
3819 (display "success!\n")
3824 In this example, the @code{(guix build utils)} module is automatically
3825 pulled into the isolated build environment of our gexp, such that
3826 @code{(use-modules (guix build utils))} works as expected.
3828 @cindex module closure
3829 @findex source-module-closure
3830 Usually you want the @emph{closure} of the module to be imported---i.e.,
3831 the module itself and all the modules it depends on---rather than just
3832 the module; failing to do that, attempts to use the module will fail
3833 because of missing dependent modules. The @code{source-module-closure}
3834 procedure computes the closure of a module by looking at its source file
3835 headers, which comes in handy in this case:
3838 (use-modules (guix modules)) ;for 'source-module-closure'
3840 (with-imported-modules (source-module-closure
3841 '((guix build utils)
3843 (gexp->derivation "something-with-vms"
3845 (use-modules (guix build utils)
3850 The syntactic form to construct gexps is summarized below.
3852 @deffn {Scheme Syntax} #~@var{exp}
3853 @deffnx {Scheme Syntax} (gexp @var{exp})
3854 Return a G-expression containing @var{exp}. @var{exp} may contain one
3855 or more of the following forms:
3859 @itemx (ungexp @var{obj})
3860 Introduce a reference to @var{obj}. @var{obj} may have one of the
3861 supported types, for example a package or a
3862 derivation, in which case the @code{ungexp} form is replaced by its
3863 output file name---e.g., @code{"/gnu/store/@dots{}-coreutils-8.22}.
3865 If @var{obj} is a list, it is traversed and references to supported
3866 objects are substituted similarly.
3868 If @var{obj} is another gexp, its contents are inserted and its
3869 dependencies are added to those of the containing gexp.
3871 If @var{obj} is another kind of object, it is inserted as is.
3873 @item #$@var{obj}:@var{output}
3874 @itemx (ungexp @var{obj} @var{output})
3875 This is like the form above, but referring explicitly to the
3876 @var{output} of @var{obj}---this is useful when @var{obj} produces
3877 multiple outputs (@pxref{Packages with Multiple Outputs}).
3880 @itemx #+@var{obj}:output
3881 @itemx (ungexp-native @var{obj})
3882 @itemx (ungexp-native @var{obj} @var{output})
3883 Same as @code{ungexp}, but produces a reference to the @emph{native}
3884 build of @var{obj} when used in a cross compilation context.
3886 @item #$output[:@var{output}]
3887 @itemx (ungexp output [@var{output}])
3888 Insert a reference to derivation output @var{output}, or to the main
3889 output when @var{output} is omitted.
3891 This only makes sense for gexps passed to @code{gexp->derivation}.
3894 @itemx (ungexp-splicing @var{lst})
3895 Like the above, but splices the contents of @var{lst} inside the
3899 @itemx (ungexp-native-splicing @var{lst})
3900 Like the above, but refers to native builds of the objects listed in
3905 G-expressions created by @code{gexp} or @code{#~} are run-time objects
3906 of the @code{gexp?} type (see below.)
3909 @deffn {Scheme Syntax} with-imported-modules @var{modules} @var{body}@dots{}
3910 Mark the gexps defined in @var{body}@dots{} as requiring @var{modules}
3911 in their execution environment. @var{modules} must be a list of Guile
3912 module names, such as @code{'((guix build utils) (guix build gremlin))}.
3914 This form has @emph{lexical} scope: it has an effect on the gexps
3915 directly defined in @var{body}@dots{}, but not on those defined, say, in
3916 procedures called from @var{body}@dots{}.
3919 @deffn {Scheme Procedure} gexp? @var{obj}
3920 Return @code{#t} if @var{obj} is a G-expression.
3923 G-expressions are meant to be written to disk, either as code building
3924 some derivation, or as plain files in the store. The monadic procedures
3925 below allow you to do that (@pxref{The Store Monad}, for more
3926 information about monads.)
3928 @deffn {Monadic Procedure} gexp->derivation @var{name} @var{exp} @
3929 [#:system (%current-system)] [#:target #f] [#:graft? #t] @
3930 [#:hash #f] [#:hash-algo #f] @
3931 [#:recursive? #f] [#:env-vars '()] [#:modules '()] @
3932 [#:module-path @var{%load-path}] @
3933 [#:references-graphs #f] [#:allowed-references #f] @
3934 [#:disallowed-references #f] @
3935 [#:leaked-env-vars #f] @
3936 [#:script-name (string-append @var{name} "-builder")] @
3937 [#:local-build? #f] [#:substitutable? #t] [#:guile-for-build #f]
3938 Return a derivation @var{name} that runs @var{exp} (a gexp) with
3939 @var{guile-for-build} (a derivation) on @var{system}; @var{exp} is
3940 stored in a file called @var{script-name}. When @var{target} is true,
3941 it is used as the cross-compilation target triplet for packages referred
3944 @var{modules} is deprecated in favor of @code{with-imported-modules}.
3946 make @var{modules} available in the evaluation context of @var{exp};
3947 @var{modules} is a list of names of Guile modules searched in
3948 @var{module-path} to be copied in the store, compiled, and made available in
3949 the load path during the execution of @var{exp}---e.g., @code{((guix
3950 build utils) (guix build gnu-build-system))}.
3952 @var{graft?} determines whether packages referred to by @var{exp} should be grafted when
3955 When @var{references-graphs} is true, it must be a list of tuples of one of the
3959 (@var{file-name} @var{package})
3960 (@var{file-name} @var{package} @var{output})
3961 (@var{file-name} @var{derivation})
3962 (@var{file-name} @var{derivation} @var{output})
3963 (@var{file-name} @var{store-item})
3966 The right-hand-side of each element of @var{references-graphs} is automatically made
3967 an input of the build process of @var{exp}. In the build environment, each
3968 @var{file-name} contains the reference graph of the corresponding item, in a simple
3971 @var{allowed-references} must be either @code{#f} or a list of output names and packages.
3972 In the latter case, the list denotes store items that the result is allowed to
3973 refer to. Any reference to another store item will lead to a build error.
3974 Similarly for @var{disallowed-references}, which can list items that must not be
3975 referenced by the outputs.
3977 The other arguments are as for @code{derivation} (@pxref{Derivations}).
3980 @cindex file-like objects
3981 The @code{local-file}, @code{plain-file}, @code{computed-file},
3982 @code{program-file}, and @code{scheme-file} procedures below return
3983 @dfn{file-like objects}. That is, when unquoted in a G-expression,
3984 these objects lead to a file in the store. Consider this G-expression:
3987 #~(system* (string-append #$glibc "/sbin/nscd") "-f"
3988 #$(local-file "/tmp/my-nscd.conf"))
3991 The effect here is to ``intern'' @file{/tmp/my-nscd.conf} by copying it
3992 to the store. Once expanded, for instance @i{via}
3993 @code{gexp->derivation}, the G-expression refers to that copy under
3994 @file{/gnu/store}; thus, modifying or removing the file in @file{/tmp}
3995 does not have any effect on what the G-expression does.
3996 @code{plain-file} can be used similarly; it differs in that the file
3997 content is directly passed as a string.
3999 @deffn {Scheme Procedure} local-file @var{file} [@var{name}] @
4000 [#:recursive? #f] [#:select? (const #t)]
4001 Return an object representing local file @var{file} to add to the store; this
4002 object can be used in a gexp. If @var{file} is a relative file name, it is looked
4003 up relative to the source file where this form appears. @var{file} will be added to
4004 the store under @var{name}--by default the base name of @var{file}.
4006 When @var{recursive?} is true, the contents of @var{file} are added recursively; if @var{file}
4007 designates a flat file and @var{recursive?} is true, its contents are added, and its
4008 permission bits are kept.
4010 When @var{recursive?} is true, call @code{(@var{select?} @var{file}
4011 @var{stat})} for each directory entry, where @var{file} is the entry's
4012 absolute file name and @var{stat} is the result of @code{lstat}; exclude
4013 entries for which @var{select?} does not return true.
4015 This is the declarative counterpart of the @code{interned-file} monadic
4016 procedure (@pxref{The Store Monad, @code{interned-file}}).
4019 @deffn {Scheme Procedure} plain-file @var{name} @var{content}
4020 Return an object representing a text file called @var{name} with the given
4021 @var{content} (a string) to be added to the store.
4023 This is the declarative counterpart of @code{text-file}.
4026 @deffn {Scheme Procedure} computed-file @var{name} @var{gexp} @
4027 [#:options '(#:local-build? #t)]
4028 Return an object representing the store item @var{name}, a file or
4029 directory computed by @var{gexp}. @var{options}
4030 is a list of additional arguments to pass to @code{gexp->derivation}.
4032 This is the declarative counterpart of @code{gexp->derivation}.
4035 @deffn {Monadic Procedure} gexp->script @var{name} @var{exp}
4036 Return an executable script @var{name} that runs @var{exp} using
4037 @var{guile}, with @var{exp}'s imported modules in its search path.
4039 The example below builds a script that simply invokes the @command{ls}
4043 (use-modules (guix gexp) (gnu packages base))
4045 (gexp->script "list-files"
4046 #~(execl (string-append #$coreutils "/bin/ls")
4050 When ``running'' it through the store (@pxref{The Store Monad,
4051 @code{run-with-store}}), we obtain a derivation that produces an
4052 executable file @file{/gnu/store/@dots{}-list-files} along these lines:
4055 #!/gnu/store/@dots{}-guile-2.0.11/bin/guile -ds
4057 (execl (string-append "/gnu/store/@dots{}-coreutils-8.22"/bin/ls")
4062 @deffn {Scheme Procedure} program-file @var{name} @var{exp} @
4064 Return an object representing the executable store item @var{name} that
4065 runs @var{gexp}. @var{guile} is the Guile package used to execute that
4068 This is the declarative counterpart of @code{gexp->script}.
4071 @deffn {Monadic Procedure} gexp->file @var{name} @var{exp} @
4072 [#:set-load-path? #t]
4073 Return a derivation that builds a file @var{name} containing @var{exp}.
4074 When @var{set-load-path?} is true, emit code in the resulting file to
4075 set @code{%load-path} and @code{%load-compiled-path} to honor
4076 @var{exp}'s imported modules.
4078 The resulting file holds references to all the dependencies of @var{exp}
4079 or a subset thereof.
4082 @deffn {Scheme Procedure} scheme-file @var{name} @var{exp}
4083 Return an object representing the Scheme file @var{name} that contains
4086 This is the declarative counterpart of @code{gexp->file}.
4089 @deffn {Monadic Procedure} text-file* @var{name} @var{text} @dots{}
4090 Return as a monadic value a derivation that builds a text file
4091 containing all of @var{text}. @var{text} may list, in addition to
4092 strings, objects of any type that can be used in a gexp: packages,
4093 derivations, local file objects, etc. The resulting store file holds
4094 references to all these.
4096 This variant should be preferred over @code{text-file} anytime the file
4097 to create will reference items from the store. This is typically the
4098 case when building a configuration file that embeds store file names,
4102 (define (profile.sh)
4103 ;; Return the name of a shell script in the store that
4104 ;; initializes the 'PATH' environment variable.
4105 (text-file* "profile.sh"
4106 "export PATH=" coreutils "/bin:"
4107 grep "/bin:" sed "/bin\n"))
4110 In this example, the resulting @file{/gnu/store/@dots{}-profile.sh} file
4111 will reference @var{coreutils}, @var{grep}, and @var{sed}, thereby
4112 preventing them from being garbage-collected during its lifetime.
4115 @deffn {Scheme Procedure} mixed-text-file @var{name} @var{text} @dots{}
4116 Return an object representing store file @var{name} containing
4117 @var{text}. @var{text} is a sequence of strings and file-like objects,
4121 (mixed-text-file "profile"
4122 "export PATH=" coreutils "/bin:" grep "/bin")
4125 This is the declarative counterpart of @code{text-file*}.
4128 Of course, in addition to gexps embedded in ``host'' code, there are
4129 also modules containing build tools. To make it clear that they are
4130 meant to be used in the build stratum, these modules are kept in the
4131 @code{(guix build @dots{})} name space.
4133 @cindex lowering, of high-level objects in gexps
4134 Internally, high-level objects are @dfn{lowered}, using their compiler,
4135 to either derivations or store items. For instance, lowering a package
4136 yields a derivation, and lowering a @code{plain-file} yields a store
4137 item. This is achieved using the @code{lower-object} monadic procedure.
4139 @deffn {Monadic Procedure} lower-object @var{obj} [@var{system}] @
4141 Return as a value in @var{%store-monad} the derivation or store item
4142 corresponding to @var{obj} for @var{system}, cross-compiling for
4143 @var{target} if @var{target} is true. @var{obj} must be an object that
4144 has an associated gexp compiler, such as a @code{<package>}.
4148 @c *********************************************************************
4152 This section describes Guix command-line utilities. Some of them are
4153 primarily targeted at developers and users who write new package
4154 definitions, while others are more generally useful. They complement
4155 the Scheme programming interface of Guix in a convenient way.
4158 * Invoking guix build:: Building packages from the command line.
4159 * Invoking guix edit:: Editing package definitions.
4160 * Invoking guix download:: Downloading a file and printing its hash.
4161 * Invoking guix hash:: Computing the cryptographic hash of a file.
4162 * Invoking guix import:: Importing package definitions.
4163 * Invoking guix refresh:: Updating package definitions.
4164 * Invoking guix lint:: Finding errors in package definitions.
4165 * Invoking guix size:: Profiling disk usage.
4166 * Invoking guix graph:: Visualizing the graph of packages.
4167 * Invoking guix environment:: Setting up development environments.
4168 * Invoking guix publish:: Sharing substitutes.
4169 * Invoking guix challenge:: Challenging substitute servers.
4170 * Invoking guix container:: Process isolation.
4173 @node Invoking guix build
4174 @section Invoking @command{guix build}
4176 The @command{guix build} command builds packages or derivations and
4177 their dependencies, and prints the resulting store paths. Note that it
4178 does not modify the user's profile---this is the job of the
4179 @command{guix package} command (@pxref{Invoking guix package}). Thus,
4180 it is mainly useful for distribution developers.
4182 The general syntax is:
4185 guix build @var{options} @var{package-or-derivation}@dots{}
4188 As an example, the following command builds the latest versions of Emacs
4189 and of Guile, displays their build logs, and finally displays the
4190 resulting directories:
4193 guix build emacs guile
4196 Similarly, the following command builds all the available packages:
4199 guix build --quiet --keep-going \
4200 `guix package -A | cut -f1,2 --output-delimiter=@@`
4203 @var{package-or-derivation} may be either the name of a package found in
4204 the software distribution such as @code{coreutils} or
4205 @code{coreutils-8.20}, or a derivation such as
4206 @file{/gnu/store/@dots{}-coreutils-8.19.drv}. In the former case, a
4207 package with the corresponding name (and optionally version) is searched
4208 for among the GNU distribution modules (@pxref{Package Modules}).
4210 Alternatively, the @code{--expression} option may be used to specify a
4211 Scheme expression that evaluates to a package; this is useful when
4212 disambiguating among several same-named packages or package variants is
4215 There may be zero or more @var{options}. The available options are
4216 described in the subsections below.
4219 * Common Build Options:: Build options for most commands.
4220 * Package Transformation Options:: Creating variants of packages.
4221 * Additional Build Options:: Options specific to 'guix build'.
4224 @node Common Build Options
4225 @subsection Common Build Options
4227 A number of options that control the build process are common to
4228 @command{guix build} and other commands that can spawn builds, such as
4229 @command{guix package} or @command{guix archive}. These are the
4234 @item --load-path=@var{directory}
4235 @itemx -L @var{directory}
4236 Add @var{directory} to the front of the package module search path
4237 (@pxref{Package Modules}).
4239 This allows users to define their own packages and make them visible to
4240 the command-line tools.
4244 Keep the build tree of failed builds. Thus, if a build fails, its build
4245 tree is kept under @file{/tmp}, in a directory whose name is shown at
4246 the end of the build log. This is useful when debugging build issues.
4250 Keep going when some of the derivations fail to build; return only once
4251 all the builds have either completed or failed.
4253 The default behavior is to stop as soon as one of the specified
4254 derivations has failed.
4258 Do not build the derivations.
4261 When substituting a pre-built binary fails, fall back to building
4264 @item --substitute-urls=@var{urls}
4265 @anchor{client-substitute-urls}
4266 Consider @var{urls} the whitespace-separated list of substitute source
4267 URLs, overriding the default list of URLs of @command{guix-daemon}
4268 (@pxref{daemon-substitute-urls,, @command{guix-daemon} URLs}).
4270 This means that substitutes may be downloaded from @var{urls}, provided
4271 they are signed by a key authorized by the system administrator
4272 (@pxref{Substitutes}).
4274 When @var{urls} is the empty string, substitutes are effectively
4277 @item --no-substitutes
4278 Do not use substitutes for build products. That is, always build things
4279 locally instead of allowing downloads of pre-built binaries
4280 (@pxref{Substitutes}).
4283 Do not ``graft'' packages. In practice, this means that package updates
4284 available as grafts are not applied. @xref{Security Updates}, for more
4285 information on grafts.
4287 @item --rounds=@var{n}
4288 Build each derivation @var{n} times in a row, and raise an error if
4289 consecutive build results are not bit-for-bit identical.
4291 This is a useful way to detect non-deterministic builds processes.
4292 Non-deterministic build processes are a problem because they make it
4293 practically impossible for users to @emph{verify} whether third-party
4294 binaries are genuine. @xref{Invoking guix challenge}, for more.
4296 Note that, currently, the differing build results are not kept around,
4297 so you will have to manually investigate in case of an error---e.g., by
4298 stashing one of the build results with @code{guix archive --export}
4299 (@pxref{Invoking guix archive}), then rebuilding, and finally comparing
4302 @item --no-build-hook
4303 Do not attempt to offload builds @i{via} the ``build hook'' of the daemon
4304 (@pxref{Daemon Offload Setup}). That is, always build things locally
4305 instead of offloading builds to remote machines.
4307 @item --max-silent-time=@var{seconds}
4308 When the build or substitution process remains silent for more than
4309 @var{seconds}, terminate it and report a build failure.
4311 @item --timeout=@var{seconds}
4312 Likewise, when the build or substitution process lasts for more than
4313 @var{seconds}, terminate it and report a build failure.
4315 By default there is no timeout. This behavior can be restored with
4318 @item --verbosity=@var{level}
4319 Use the given verbosity level. @var{level} must be an integer between 0
4320 and 5; higher means more verbose output. Setting a level of 4 or more
4321 may be helpful when debugging setup issues with the build daemon.
4323 @item --cores=@var{n}
4325 Allow the use of up to @var{n} CPU cores for the build. The special
4326 value @code{0} means to use as many CPU cores as available.
4328 @item --max-jobs=@var{n}
4330 Allow at most @var{n} build jobs in parallel. @xref{Invoking
4331 guix-daemon, @code{--max-jobs}}, for details about this option and the
4332 equivalent @command{guix-daemon} option.
4336 Behind the scenes, @command{guix build} is essentially an interface to
4337 the @code{package-derivation} procedure of the @code{(guix packages)}
4338 module, and to the @code{build-derivations} procedure of the @code{(guix
4339 derivations)} module.
4341 In addition to options explicitly passed on the command line,
4342 @command{guix build} and other @command{guix} commands that support
4343 building honor the @code{GUIX_BUILD_OPTIONS} environment variable.
4345 @defvr {Environment Variable} GUIX_BUILD_OPTIONS
4346 Users can define this variable to a list of command line options that
4347 will automatically be used by @command{guix build} and other
4348 @command{guix} commands that can perform builds, as in the example
4352 $ export GUIX_BUILD_OPTIONS="--no-substitutes -c 2 -L /foo/bar"
4355 These options are parsed independently, and the result is appended to
4356 the parsed command-line options.
4360 @node Package Transformation Options
4361 @subsection Package Transformation Options
4363 @cindex package variants
4364 Another set of command-line options supported by @command{guix build}
4365 and also @command{guix package} are @dfn{package transformation
4366 options}. These are options that make it possible to define @dfn{package
4367 variants}---for instance, packages built from different source code.
4368 This is a convenient way to create customized packages on the fly
4369 without having to type in the definitions of package variants
4370 (@pxref{Defining Packages}).
4374 @item --with-source=@var{source}
4375 Use @var{source} as the source of the corresponding package.
4376 @var{source} must be a file name or a URL, as for @command{guix
4377 download} (@pxref{Invoking guix download}).
4379 The ``corresponding package'' is taken to be the one specified on the
4380 command line the name of which matches the base of @var{source}---e.g.,
4381 if @var{source} is @code{/src/guile-2.0.10.tar.gz}, the corresponding
4382 package is @code{guile}. Likewise, the version string is inferred from
4383 @var{source}; in the previous example, it is @code{2.0.10}.
4385 This option allows users to try out versions of packages other than the
4386 one provided by the distribution. The example below downloads
4387 @file{ed-1.7.tar.gz} from a GNU mirror and uses that as the source for
4388 the @code{ed} package:
4391 guix build ed --with-source=mirror://gnu/ed/ed-1.7.tar.gz
4394 As a developer, @code{--with-source} makes it easy to test release
4398 guix build guile --with-source=../guile-2.0.9.219-e1bb7.tar.xz
4401 @dots{} or to build from a checkout in a pristine environment:
4404 $ git clone git://git.sv.gnu.org/guix.git
4405 $ guix build guix --with-source=./guix
4408 @item --with-input=@var{package}=@var{replacement}
4409 Replace dependency on @var{package} by a dependency on
4410 @var{replacement}. @var{package} must be a package name, and
4411 @var{replacement} must be a package specification such as @code{guile}
4412 or @code{guile@@1.8}.
4414 For instance, the following command builds Guix, but replaces its
4415 dependency on the current stable version of Guile with a dependency on
4416 the development version of Guile, @code{guile-next}:
4419 guix build --with-input=guile=guile-next guix
4422 This is a recursive, deep replacement. So in this example, both
4423 @code{guix} and its dependency @code{guile-json} (which also depends on
4424 @code{guile}) get rebuilt against @code{guile-next}.
4426 This is implemented using the @code{package-input-rewriting} Scheme
4427 procedure (@pxref{Defining Packages, @code{package-input-rewriting}}).
4430 @node Additional Build Options
4431 @subsection Additional Build Options
4433 The command-line options presented below are specific to @command{guix
4440 Build quietly, without displaying the build log. Upon completion, the
4441 build log is kept in @file{/var} (or similar) and can always be
4442 retrieved using the @option{--log-file} option.
4444 @item --file=@var{file}
4445 @itemx -f @var{file}
4447 Build the package or derivation that the code within @var{file}
4450 As an example, @var{file} might contain a package definition like this
4451 (@pxref{Defining Packages}):
4454 @verbatiminclude package-hello.scm
4457 @item --expression=@var{expr}
4458 @itemx -e @var{expr}
4459 Build the package or derivation @var{expr} evaluates to.
4461 For example, @var{expr} may be @code{(@@ (gnu packages guile)
4462 guile-1.8)}, which unambiguously designates this specific variant of
4463 version 1.8 of Guile.
4465 Alternatively, @var{expr} may be a G-expression, in which case it is used
4466 as a build program passed to @code{gexp->derivation}
4467 (@pxref{G-Expressions}).
4469 Lastly, @var{expr} may refer to a zero-argument monadic procedure
4470 (@pxref{The Store Monad}). The procedure must return a derivation as a
4471 monadic value, which is then passed through @code{run-with-store}.
4475 Build the source derivations of the packages, rather than the packages
4478 For instance, @code{guix build -S gcc} returns something like
4479 @file{/gnu/store/@dots{}-gcc-4.7.2.tar.bz2}, which is the GCC
4482 The returned source tarball is the result of applying any patches and
4483 code snippets specified in the package @code{origin} (@pxref{Defining
4487 Fetch and return the source of @var{package-or-derivation} and all their
4488 dependencies, recursively. This is a handy way to obtain a local copy
4489 of all the source code needed to build @var{packages}, allowing you to
4490 eventually build them even without network access. It is an extension
4491 of the @code{--source} option and can accept one of the following
4492 optional argument values:
4496 This value causes the @code{--sources} option to behave in the same way
4497 as the @code{--source} option.
4500 Build the source derivations of all packages, including any source that
4501 might be listed as @code{inputs}. This is the default value.
4504 $ guix build --sources tzdata
4505 The following derivations will be built:
4506 /gnu/store/@dots{}-tzdata2015b.tar.gz.drv
4507 /gnu/store/@dots{}-tzcode2015b.tar.gz.drv
4511 Build the source derivations of all packages, as well of all transitive
4512 inputs to the packages. This can be used e.g. to
4513 prefetch package source for later offline building.
4516 $ guix build --sources=transitive tzdata
4517 The following derivations will be built:
4518 /gnu/store/@dots{}-tzcode2015b.tar.gz.drv
4519 /gnu/store/@dots{}-findutils-4.4.2.tar.xz.drv
4520 /gnu/store/@dots{}-grep-2.21.tar.xz.drv
4521 /gnu/store/@dots{}-coreutils-8.23.tar.xz.drv
4522 /gnu/store/@dots{}-make-4.1.tar.xz.drv
4523 /gnu/store/@dots{}-bash-4.3.tar.xz.drv
4529 @item --system=@var{system}
4530 @itemx -s @var{system}
4531 Attempt to build for @var{system}---e.g., @code{i686-linux}---instead of
4532 the system type of the build host.
4534 An example use of this is on Linux-based systems, which can emulate
4535 different personalities. For instance, passing
4536 @code{--system=i686-linux} on an @code{x86_64-linux} system allows users
4537 to build packages in a complete 32-bit environment.
4539 @item --target=@var{triplet}
4540 @cindex cross-compilation
4541 Cross-build for @var{triplet}, which must be a valid GNU triplet, such
4542 as @code{"mips64el-linux-gnu"} (@pxref{Configuration Names, GNU
4543 configuration triplets,, configure, GNU Configure and Build System}).
4545 @anchor{build-check}
4547 @cindex determinism, checking
4548 @cindex reproducibility, checking
4549 Rebuild @var{package-or-derivation}, which are already available in the
4550 store, and raise an error if the build results are not bit-for-bit
4553 This mechanism allows you to check whether previously installed
4554 substitutes are genuine (@pxref{Substitutes}), or whether the build result
4555 of a package is deterministic. @xref{Invoking guix challenge}, for more
4556 background information and tools.
4558 When used in conjunction with @option{--keep-failed}, the differing
4559 output is kept in the store, under @file{/gnu/store/@dots{}-check}.
4560 This makes it easy to look for differences between the two results.
4564 Return the derivation paths, not the output paths, of the given
4567 @item --root=@var{file}
4568 @itemx -r @var{file}
4569 Make @var{file} a symlink to the result, and register it as a garbage
4573 Return the build log file names or URLs for the given
4574 @var{package-or-derivation}, or raise an error if build logs are
4577 This works regardless of how packages or derivations are specified. For
4578 instance, the following invocations are equivalent:
4581 guix build --log-file `guix build -d guile`
4582 guix build --log-file `guix build guile`
4583 guix build --log-file guile
4584 guix build --log-file -e '(@@ (gnu packages guile) guile-2.0)'
4587 If a log is unavailable locally, and unless @code{--no-substitutes} is
4588 passed, the command looks for a corresponding log on one of the
4589 substitute servers (as specified with @code{--substitute-urls}.)
4591 So for instance, imagine you want to see the build log of GDB on MIPS,
4592 but you are actually on an @code{x86_64} machine:
4595 $ guix build --log-file gdb -s mips64el-linux
4596 https://hydra.gnu.org/log/@dots{}-gdb-7.10
4599 You can freely access a huge library of build logs!
4603 @node Invoking guix edit
4604 @section Invoking @command{guix edit}
4606 @cindex package definition, editing
4607 So many packages, so many source files! The @command{guix edit} command
4608 facilitates the life of users and packagers by pointing their editor at
4609 the source file containing the definition of the specified packages.
4613 guix edit gcc@@4.9 vim
4617 launches the program specified in the @code{VISUAL} or in the
4618 @code{EDITOR} environment variable to view the recipe of GCC@tie{}4.9.3
4621 If you are using a Guix Git checkout (@pxref{Building from Git}), or
4622 have created your own packages on @code{GUIX_PACKAGE_PATH}
4623 (@pxref{Defining Packages}), you will be able to edit the package
4624 recipes. Otherwise, you will be able to examine the read-only recipes
4625 for packages currently in the store.
4627 If you are using Emacs, note that the Emacs user interface provides the
4628 @kbd{M-x guix-edit} command and a similar functionality in the ``package
4629 info'' and ``package list'' buffers created by the @kbd{M-x
4630 guix-search-by-name} and similar commands (@pxref{Emacs Commands}).
4633 @node Invoking guix download
4634 @section Invoking @command{guix download}
4636 When writing a package definition, developers typically need to download
4637 a source tarball, compute its SHA256 hash, and write that
4638 hash in the package definition (@pxref{Defining Packages}). The
4639 @command{guix download} tool helps with this task: it downloads a file
4640 from the given URI, adds it to the store, and prints both its file name
4641 in the store and its SHA256 hash.
4643 The fact that the downloaded file is added to the store saves bandwidth:
4644 when the developer eventually tries to build the newly defined package
4645 with @command{guix build}, the source tarball will not have to be
4646 downloaded again because it is already in the store. It is also a
4647 convenient way to temporarily stash files, which may be deleted
4648 eventually (@pxref{Invoking guix gc}).
4650 The @command{guix download} command supports the same URIs as used in
4651 package definitions. In particular, it supports @code{mirror://} URIs.
4652 @code{https} URIs (HTTP over TLS) are supported @emph{provided} the
4653 Guile bindings for GnuTLS are available in the user's environment; when
4654 they are not available, an error is raised. @xref{Guile Preparations,
4655 how to install the GnuTLS bindings for Guile,, gnutls-guile,
4656 GnuTLS-Guile}, for more information.
4658 The following option is available:
4661 @item --format=@var{fmt}
4663 Write the hash in the format specified by @var{fmt}. For more
4664 information on the valid values for @var{fmt}, @pxref{Invoking guix hash}.
4667 @node Invoking guix hash
4668 @section Invoking @command{guix hash}
4670 The @command{guix hash} command computes the SHA256 hash of a file.
4671 It is primarily a convenience tool for anyone contributing to the
4672 distribution: it computes the cryptographic hash of a file, which can be
4673 used in the definition of a package (@pxref{Defining Packages}).
4675 The general syntax is:
4678 guix hash @var{option} @var{file}
4681 @command{guix hash} has the following option:
4685 @item --format=@var{fmt}
4687 Write the hash in the format specified by @var{fmt}.
4689 Supported formats: @code{nix-base32}, @code{base32}, @code{base16}
4690 (@code{hex} and @code{hexadecimal} can be used as well).
4692 If the @option{--format} option is not specified, @command{guix hash}
4693 will output the hash in @code{nix-base32}. This representation is used
4694 in the definitions of packages.
4698 Compute the hash on @var{file} recursively.
4700 In this case, the hash is computed on an archive containing @var{file},
4701 including its children if it is a directory. Some of the metadata of
4702 @var{file} is part of the archive; for instance, when @var{file} is a
4703 regular file, the hash is different depending on whether @var{file} is
4704 executable or not. Metadata such as time stamps has no impact on the
4705 hash (@pxref{Invoking guix archive}).
4706 @c FIXME: Replace xref above with xref to an ``Archive'' section when
4710 As an example, here is how you would compute the hash of a Git checkout,
4711 which is useful when using the @code{git-fetch} method (@pxref{origin
4715 $ git clone http://example.org/foo.git
4722 @node Invoking guix import
4723 @section Invoking @command{guix import}
4725 @cindex importing packages
4726 @cindex package import
4727 @cindex package conversion
4728 The @command{guix import} command is useful for people who would like to
4729 add a package to the distribution with as little work as
4730 possible---a legitimate demand. The command knows of a few
4731 repositories from which it can ``import'' package metadata. The result
4732 is a package definition, or a template thereof, in the format we know
4733 (@pxref{Defining Packages}).
4735 The general syntax is:
4738 guix import @var{importer} @var{options}@dots{}
4741 @var{importer} specifies the source from which to import package
4742 metadata, and @var{options} specifies a package identifier and other
4743 options specific to @var{importer}. Currently, the available
4748 Import metadata for the given GNU package. This provides a template
4749 for the latest version of that GNU package, including the hash of its
4750 source tarball, and its canonical synopsis and description.
4752 Additional information such as the package dependencies and its
4753 license needs to be figured out manually.
4755 For example, the following command returns a package definition for
4759 guix import gnu hello
4762 Specific command-line options are:
4765 @item --key-download=@var{policy}
4766 As for @code{guix refresh}, specify the policy to handle missing OpenPGP
4767 keys when verifying the package signature. @xref{Invoking guix
4768 refresh, @code{--key-download}}.
4773 Import metadata from the @uref{https://pypi.python.org/, Python Package
4774 Index}@footnote{This functionality requires Guile-JSON to be installed.
4775 @xref{Requirements}.}. Information is taken from the JSON-formatted
4776 description available at @code{pypi.python.org} and usually includes all
4777 the relevant information, including package dependencies. For maximum
4778 efficiency, it is recommended to install the @command{unzip} utility, so
4779 that the importer can unzip Python wheels and gather data from them.
4781 The command below imports metadata for the @code{itsdangerous} Python
4785 guix import pypi itsdangerous
4790 Import metadata from @uref{https://rubygems.org/,
4791 RubyGems}@footnote{This functionality requires Guile-JSON to be
4792 installed. @xref{Requirements}.}. Information is taken from the
4793 JSON-formatted description available at @code{rubygems.org} and includes
4794 most relevant information, including runtime dependencies. There are
4795 some caveats, however. The metadata doesn't distinguish between
4796 synopses and descriptions, so the same string is used for both fields.
4797 Additionally, the details of non-Ruby dependencies required to build
4798 native extensions is unavailable and left as an exercise to the
4801 The command below imports metadata for the @code{rails} Ruby package:
4804 guix import gem rails
4809 Import metadata from @uref{https://www.metacpan.org/, MetaCPAN}@footnote{This
4810 functionality requires Guile-JSON to be installed.
4811 @xref{Requirements}.}.
4812 Information is taken from the JSON-formatted metadata provided through
4813 @uref{https://api.metacpan.org/, MetaCPAN's API} and includes most
4814 relevant information, such as module dependencies. License information
4815 should be checked closely. If Perl is available in the store, then the
4816 @code{corelist} utility will be used to filter core modules out of the
4817 list of dependencies.
4819 The command command below imports metadata for the @code{Acme::Boolean}
4823 guix import cpan Acme::Boolean
4828 @cindex Bioconductor
4829 Import metadata from @uref{http://cran.r-project.org/, CRAN}, the
4830 central repository for the @uref{http://r-project.org, GNU@tie{}R
4831 statistical and graphical environment}.
4833 Information is extracted from the @code{DESCRIPTION} file of the package.
4835 The command command below imports metadata for the @code{Cairo}
4839 guix import cran Cairo
4842 When @code{--archive=bioconductor} is added, metadata is imported from
4843 @uref{http://www.bioconductor.org/, Bioconductor}, a repository of R
4844 packages for for the analysis and comprehension of high-throughput
4845 genomic data in bioinformatics.
4847 Information is extracted from the @code{DESCRIPTION} file of a package
4848 published on the web interface of the Bioconductor SVN repository.
4850 The command below imports metadata for the @code{GenomicRanges}
4854 guix import cran --archive=bioconductor GenomicRanges
4858 Import metadata from a local copy of the source of the
4859 @uref{http://nixos.org/nixpkgs/, Nixpkgs distribution}@footnote{This
4860 relies on the @command{nix-instantiate} command of
4861 @uref{http://nixos.org/nix/, Nix}.}. Package definitions in Nixpkgs are
4862 typically written in a mixture of Nix-language and Bash code. This
4863 command only imports the high-level package structure that is written in
4864 the Nix language. It normally includes all the basic fields of a
4867 When importing a GNU package, the synopsis and descriptions are replaced
4868 by their canonical upstream variant.
4870 Usually, you will first need to do:
4873 export NIX_REMOTE=daemon
4877 so that @command{nix-instantiate} does not try to open the Nix database.
4879 As an example, the command below imports the package definition of
4880 LibreOffice (more precisely, it imports the definition of the package
4881 bound to the @code{libreoffice} top-level attribute):
4884 guix import nix ~/path/to/nixpkgs libreoffice
4889 Import metadata from the Haskell community's central package archive
4890 @uref{https://hackage.haskell.org/, Hackage}. Information is taken from
4891 Cabal files and includes all the relevant information, including package
4894 Specific command-line options are:
4899 Read a Cabal file from standard input.
4900 @item --no-test-dependencies
4902 Do not include dependencies required only by the test suites.
4903 @item --cabal-environment=@var{alist}
4904 @itemx -e @var{alist}
4905 @var{alist} is a Scheme alist defining the environment in which the
4906 Cabal conditionals are evaluated. The accepted keys are: @code{os},
4907 @code{arch}, @code{impl} and a string representing the name of a flag.
4908 The value associated with a flag has to be either the symbol
4909 @code{true} or @code{false}. The value associated with other keys
4910 has to conform to the Cabal file format definition. The default value
4911 associated with the keys @code{os}, @code{arch} and @code{impl} is
4912 @samp{linux}, @samp{x86_64} and @samp{ghc}, respectively.
4915 The command below imports metadata for the latest version of the
4916 @code{HTTP} Haskell package without including test dependencies and
4917 specifying the value of the flag @samp{network-uri} as @code{false}:
4920 guix import hackage -t -e "'((\"network-uri\" . false))" HTTP
4923 A specific package version may optionally be specified by following the
4924 package name by an at-sign and a version number as in the following example:
4927 guix import hackage mtl@@2.1.3.1
4932 Import metadata from an Emacs Lisp Package Archive (ELPA) package
4933 repository (@pxref{Packages,,, emacs, The GNU Emacs Manual}).
4935 Specific command-line options are:
4938 @item --archive=@var{repo}
4939 @itemx -a @var{repo}
4940 @var{repo} identifies the archive repository from which to retrieve the
4941 information. Currently the supported repositories and their identifiers
4945 @uref{http://elpa.gnu.org/packages, GNU}, selected by the @code{gnu}
4946 identifier. This is the default.
4949 @uref{http://stable.melpa.org/packages, MELPA-Stable}, selected by the
4950 @code{melpa-stable} identifier.
4953 @uref{http://melpa.org/packages, MELPA}, selected by the @code{melpa}
4959 The structure of the @command{guix import} code is modular. It would be
4960 useful to have more importers for other package formats, and your help
4961 is welcome here (@pxref{Contributing}).
4963 @node Invoking guix refresh
4964 @section Invoking @command{guix refresh}
4966 The primary audience of the @command{guix refresh} command is developers
4967 of the GNU software distribution. By default, it reports any packages
4968 provided by the distribution that are outdated compared to the latest
4969 upstream version, like this:
4973 gnu/packages/gettext.scm:29:13: gettext would be upgraded from 0.18.1.1 to 0.18.2.1
4974 gnu/packages/glib.scm:77:12: glib would be upgraded from 2.34.3 to 2.37.0
4977 It does so by browsing the FTP directory of each package and determining
4978 the highest version number of the source tarballs therein. The command
4979 knows how to update specific types of packages: GNU packages, ELPA
4980 packages, etc.---see the documentation for @option{--type} below. The
4981 are many packages, though, for which it lacks a method to determine
4982 whether a new upstream release is available. However, the mechanism is
4983 extensible, so feel free to get in touch with us to add a new method!
4985 When passed @code{--update}, it modifies distribution source files to
4986 update the version numbers and source tarball hashes of those package
4987 recipes (@pxref{Defining Packages}). This is achieved by downloading
4988 each package's latest source tarball and its associated OpenPGP
4989 signature, authenticating the downloaded tarball against its signature
4990 using @command{gpg}, and finally computing its hash. When the public
4991 key used to sign the tarball is missing from the user's keyring, an
4992 attempt is made to automatically retrieve it from a public key server;
4993 when this is successful, the key is added to the user's keyring; otherwise,
4994 @command{guix refresh} reports an error.
4996 The following options are supported:
5000 @item --expression=@var{expr}
5001 @itemx -e @var{expr}
5002 Consider the package @var{expr} evaluates to.
5004 This is useful to precisely refer to a package, as in this example:
5007 guix refresh -l -e '(@@@@ (gnu packages commencement) glibc-final)'
5010 This command lists the dependents of the ``final'' libc (essentially all
5015 Update distribution source files (package recipes) in place. This is
5016 usually run from a checkout of the Guix source tree (@pxref{Running
5017 Guix Before It Is Installed}):
5020 $ ./pre-inst-env guix refresh -s non-core
5023 @xref{Defining Packages}, for more information on package definitions.
5025 @item --select=[@var{subset}]
5026 @itemx -s @var{subset}
5027 Select all the packages in @var{subset}, one of @code{core} or
5030 The @code{core} subset refers to all the packages at the core of the
5031 distribution---i.e., packages that are used to build ``everything
5032 else''. This includes GCC, libc, Binutils, Bash, etc. Usually,
5033 changing one of these packages in the distribution entails a rebuild of
5034 all the others. Thus, such updates are an inconvenience to users in
5035 terms of build time or bandwidth used to achieve the upgrade.
5037 The @code{non-core} subset refers to the remaining packages. It is
5038 typically useful in cases where an update of the core packages would be
5041 @item --type=@var{updater}
5042 @itemx -t @var{updater}
5043 Select only packages handled by @var{updater} (may be a comma-separated
5044 list of updaters). Currently, @var{updater} may be one of:
5048 the updater for GNU packages;
5050 the updater for GNOME packages;
5052 the updater for KDE packages;
5054 the updater for X.org packages;
5056 the updater for @uref{http://elpa.gnu.org/, ELPA} packages;
5058 the updater for @uref{http://cran.r-project.org/, CRAN} packages;
5060 the updater for @uref{http://www.bioconductor.org/, Bioconductor} R packages;
5062 the updater for @uref{https://pypi.python.org, PyPI} packages.
5064 the updater for @uref{https://rubygems.org, RubyGems} packages.
5066 the updater for @uref{https://github.com, GitHub} packages.
5068 the updater for @uref{https://hackage.haskell.org, Hackage} packages.
5071 For instance, the following command only checks for updates of Emacs
5072 packages hosted at @code{elpa.gnu.org} and for updates of CRAN packages:
5075 $ guix refresh --type=elpa,cran
5076 gnu/packages/statistics.scm:819:13: r-testthat would be upgraded from 0.10.0 to 0.11.0
5077 gnu/packages/emacs.scm:856:13: emacs-auctex would be upgraded from 11.88.6 to 11.88.9
5082 In addition, @command{guix refresh} can be passed one or more package
5083 names, as in this example:
5086 $ ./pre-inst-env guix refresh -u emacs idutils gcc-4.8.4
5090 The command above specifically updates the @code{emacs} and
5091 @code{idutils} packages. The @code{--select} option would have no
5092 effect in this case.
5094 When considering whether to upgrade a package, it is sometimes
5095 convenient to know which packages would be affected by the upgrade and
5096 should be checked for compatibility. For this the following option may
5097 be used when passing @command{guix refresh} one or more package names:
5101 @item --list-updaters
5103 List available updaters and exit (see @option{--type} above.)
5105 @item --list-dependent
5107 List top-level dependent packages that would need to be rebuilt as a
5108 result of upgrading one or more packages.
5112 Be aware that the @code{--list-dependent} option only
5113 @emph{approximates} the rebuilds that would be required as a result of
5114 an upgrade. More rebuilds might be required under some circumstances.
5117 $ guix refresh --list-dependent flex
5118 Building the following 120 packages would ensure 213 dependent packages are rebuilt:
5119 hop-2.4.0 geiser-0.4 notmuch-0.18 mu-0.9.9.5 cflow-1.4 idutils-4.6 @dots{}
5122 The command above lists a set of packages that could be built to check
5123 for compatibility with an upgraded @code{flex} package.
5125 The following options can be used to customize GnuPG operation:
5129 @item --gpg=@var{command}
5130 Use @var{command} as the GnuPG 2.x command. @var{command} is searched
5131 for in @code{$PATH}.
5133 @item --key-download=@var{policy}
5134 Handle missing OpenPGP keys according to @var{policy}, which may be one
5139 Always download missing OpenPGP keys from the key server, and add them
5140 to the user's GnuPG keyring.
5143 Never try to download missing OpenPGP keys. Instead just bail out.
5146 When a package signed with an unknown OpenPGP key is encountered, ask
5147 the user whether to download it or not. This is the default behavior.
5150 @item --key-server=@var{host}
5151 Use @var{host} as the OpenPGP key server when importing a public key.
5155 The @code{github} updater uses the
5156 @uref{https://developer.github.com/v3/, GitHub API} to query for new
5157 releases. When used repeatedly e.g. when refreshing all packages,
5158 GitHub will eventually refuse to answer any further API requests. By
5159 default 60 API requests per hour are allowed, and a full refresh on all
5160 GitHub packages in Guix requires more than this. Authentication with
5161 GitHub through the use of an API token alleviates these limits. To use
5162 an API token, set the environment variable @code{GUIX_GITHUB_TOKEN} to a
5163 token procured from @uref{https://github.com/settings/tokens} or
5167 @node Invoking guix lint
5168 @section Invoking @command{guix lint}
5169 The @command{guix lint} command is meant to help package developers avoid
5170 common errors and use a consistent style. It runs a number of checks on
5171 a given set of packages in order to find common mistakes in their
5172 definitions. Available @dfn{checkers} include (see
5173 @code{--list-checkers} for a complete list):
5178 Validate certain typographical and stylistic rules about package
5179 descriptions and synopses.
5181 @item inputs-should-be-native
5182 Identify inputs that should most likely be native inputs.
5186 @itemx source-file-name
5187 Probe @code{home-page} and @code{source} URLs and report those that are
5188 invalid. Check that the source file name is meaningful, e.g. is not
5189 just a version number or ``git-checkout'', without a declared
5190 @code{file-name} (@pxref{origin Reference}).
5193 @cindex security vulnerabilities
5194 @cindex CVE, Common Vulnerabilities and Exposures
5195 Report known vulnerabilities found in the Common Vulnerabilities and
5196 Exposures (CVE) databases of the current and past year
5197 @uref{https://nvd.nist.gov/download.cfm#CVE_FEED, published by the US
5200 To view information about a particular vulnerability, visit pages such as:
5204 @indicateurl{https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-YYYY-ABCD}
5206 @indicateurl{https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-YYYY-ABCD}
5210 where @code{CVE-YYYY-ABCD} is the CVE identifier---e.g.,
5211 @code{CVE-2015-7554}.
5213 Package developers can specify in package recipes the
5214 @uref{https://nvd.nist.gov/cpe.cfm,Common Platform Enumeration (CPE)}
5215 name and version of the package when they differ from the name that Guix
5216 uses, as in this example:
5222 ;; CPE calls this package "grub2".
5223 (properties '((cpe-name . "grub2"))))
5227 Warn about obvious source code formatting issues: trailing white space,
5228 use of tabulations, etc.
5231 The general syntax is:
5234 guix lint @var{options} @var{package}@dots{}
5237 If no package is given on the command line, then all packages are checked.
5238 The @var{options} may be zero or more of the following:
5241 @item --list-checkers
5243 List and describe all the available checkers that will be run on packages
5248 Only enable the checkers specified in a comma-separated list using the
5249 names returned by @code{--list-checkers}.
5253 @node Invoking guix size
5254 @section Invoking @command{guix size}
5256 The @command{guix size} command helps package developers profile the
5257 disk usage of packages. It is easy to overlook the impact of an
5258 additional dependency added to a package, or the impact of using a
5259 single output for a package that could easily be split (@pxref{Packages
5260 with Multiple Outputs}). Such are the typical issues that
5261 @command{guix size} can highlight.
5263 The command can be passed a package specification such as @code{gcc-4.8}
5264 or @code{guile:debug}, or a file name in the store. Consider this
5268 $ guix size coreutils
5269 store item total self
5270 /gnu/store/@dots{}-coreutils-8.23 70.0 13.9 19.8%
5271 /gnu/store/@dots{}-gmp-6.0.0a 55.3 2.5 3.6%
5272 /gnu/store/@dots{}-acl-2.2.52 53.7 0.5 0.7%
5273 /gnu/store/@dots{}-attr-2.4.46 53.2 0.3 0.5%
5274 /gnu/store/@dots{}-gcc-4.8.4-lib 52.9 15.7 22.4%
5275 /gnu/store/@dots{}-glibc-2.21 37.2 37.2 53.1%
5279 The store items listed here constitute the @dfn{transitive closure} of
5280 Coreutils---i.e., Coreutils and all its dependencies, recursively---as
5281 would be returned by:
5284 $ guix gc -R /gnu/store/@dots{}-coreutils-8.23
5287 Here the output shows three columns next to store items. The first column,
5288 labeled ``total'', shows the size in mebibytes (MiB) of the closure of
5289 the store item---that is, its own size plus the size of all its
5290 dependencies. The next column, labeled ``self'', shows the size of the
5291 item itself. The last column shows the ratio of the size of the item
5292 itself to the space occupied by all the items listed here.
5294 In this example, we see that the closure of Coreutils weighs in at
5295 70@tie{}MiB, half of which is taken by libc. (That libc represents a
5296 large fraction of the closure is not a problem @i{per se} because it is
5297 always available on the system anyway.)
5299 When the package passed to @command{guix size} is available in the
5300 store, @command{guix size} queries the daemon to determine its
5301 dependencies, and measures its size in the store, similar to @command{du
5302 -ms --apparent-size} (@pxref{du invocation,,, coreutils, GNU
5305 When the given package is @emph{not} in the store, @command{guix size}
5306 reports information based on the available substitutes
5307 (@pxref{Substitutes}). This makes it possible it to profile disk usage of
5308 store items that are not even on disk, only available remotely.
5310 You can also specify several package names:
5313 $ guix size coreutils grep sed bash
5314 store item total self
5315 /gnu/store/@dots{}-coreutils-8.24 77.8 13.8 13.4%
5316 /gnu/store/@dots{}-grep-2.22 73.1 0.8 0.8%
5317 /gnu/store/@dots{}-bash-4.3.42 72.3 4.7 4.6%
5318 /gnu/store/@dots{}-readline-6.3 67.6 1.2 1.2%
5324 In this example we see that the combination of the four packages takes
5325 102.3@tie{}MiB in total, which is much less than the sum of each closure
5326 since they have a lot of dependencies in common.
5328 The available options are:
5332 @item --substitute-urls=@var{urls}
5333 Use substitute information from @var{urls}.
5334 @xref{client-substitute-urls, the same option for @code{guix build}}.
5336 @item --map-file=@var{file}
5337 Write a graphical map of disk usage in PNG format to @var{file}.
5339 For the example above, the map looks like this:
5341 @image{images/coreutils-size-map,5in,, map of Coreutils disk usage
5342 produced by @command{guix size}}
5344 This option requires that
5345 @uref{http://wingolog.org/software/guile-charting/, Guile-Charting} be
5346 installed and visible in Guile's module search path. When that is not
5347 the case, @command{guix size} fails as it tries to load it.
5349 @item --system=@var{system}
5350 @itemx -s @var{system}
5351 Consider packages for @var{system}---e.g., @code{x86_64-linux}.
5355 @node Invoking guix graph
5356 @section Invoking @command{guix graph}
5359 Packages and their dependencies form a @dfn{graph}, specifically a
5360 directed acyclic graph (DAG). It can quickly become difficult to have a
5361 mental model of the package DAG, so the @command{guix graph} command
5362 provides a visual representation of the DAG. @command{guix graph}
5363 emits a DAG representation in the input format of
5364 @uref{http://www.graphviz.org/, Graphviz}, so its output can be passed
5365 directly to the @command{dot} command of Graphviz. The general
5369 guix graph @var{options} @var{package}@dots{}
5372 For example, the following command generates a PDF file representing the
5373 package DAG for the GNU@tie{}Core Utilities, showing its build-time
5377 guix graph coreutils | dot -Tpdf > dag.pdf
5380 The output looks like this:
5382 @image{images/coreutils-graph,2in,,Dependency graph of the GNU Coreutils}
5384 Nice little graph, no?
5386 But there is more than one graph! The one above is concise: it is the
5387 graph of package objects, omitting implicit inputs such as GCC, libc,
5388 grep, etc. It is often useful to have such a concise graph, but
5389 sometimes one may want to see more details. @command{guix graph} supports
5390 several types of graphs, allowing you to choose the level of detail:
5394 This is the default type used in the example above. It shows the DAG of
5395 package objects, excluding implicit dependencies. It is concise, but
5396 filters out many details.
5399 This is the package DAG, @emph{including} implicit inputs.
5401 For instance, the following command:
5404 guix graph --type=bag-emerged coreutils | dot -Tpdf > dag.pdf
5407 ... yields this bigger graph:
5409 @image{images/coreutils-bag-graph,,5in,Detailed dependency graph of the GNU Coreutils}
5411 At the bottom of the graph, we see all the implicit inputs of
5412 @var{gnu-build-system} (@pxref{Build Systems, @code{gnu-build-system}}).
5414 Now, note that the dependencies of these implicit inputs---that is, the
5415 @dfn{bootstrap dependencies} (@pxref{Bootstrapping})---are not shown
5416 here, for conciseness.
5419 Similar to @code{bag-emerged}, but this time including all the bootstrap
5422 @item bag-with-origins
5423 Similar to @code{bag}, but also showing origins and their dependencies.
5426 This is the most detailed representation: It shows the DAG of
5427 derivations (@pxref{Derivations}) and plain store items. Compared to
5428 the above representation, many additional nodes are visible, including
5429 build scripts, patches, Guile modules, etc.
5431 For this type of graph, it is also possible to pass a @file{.drv} file
5432 name instead of a package name, as in:
5435 guix graph -t derivation `guix system build -d my-config.scm`
5439 All the types above correspond to @emph{build-time dependencies}. The
5440 following graph type represents the @emph{run-time dependencies}:
5444 This is the graph of @dfn{references} of a package output, as returned
5445 by @command{guix gc --references} (@pxref{Invoking guix gc}).
5447 If the given package output is not available in the store, @command{guix
5448 graph} attempts to obtain dependency information from substitutes.
5450 Here you can also pass a store file name instead of a package name. For
5451 example, the command below produces the reference graph of your profile
5452 (which can be big!):
5455 guix graph -t references `readlink -f ~/.guix-profile`
5459 The available options are the following:
5462 @item --type=@var{type}
5463 @itemx -t @var{type}
5464 Produce a graph output of @var{type}, where @var{type} must be one of
5465 the values listed above.
5468 List the supported graph types.
5470 @item --expression=@var{expr}
5471 @itemx -e @var{expr}
5472 Consider the package @var{expr} evaluates to.
5474 This is useful to precisely refer to a package, as in this example:
5477 guix graph -e '(@@@@ (gnu packages commencement) gnu-make-final)'
5482 @node Invoking guix environment
5483 @section Invoking @command{guix environment}
5485 @cindex reproducible build environments
5486 @cindex development environments
5487 The purpose of @command{guix environment} is to assist hackers in
5488 creating reproducible development environments without polluting their
5489 package profile. The @command{guix environment} tool takes one or more
5490 packages, builds all of their inputs, and creates a shell
5491 environment to use them.
5493 The general syntax is:
5496 guix environment @var{options} @var{package}@dots{}
5499 The following example spawns a new shell set up for the development of
5503 guix environment guile
5506 If the needed dependencies are not built yet, @command{guix environment}
5507 automatically builds them. The environment of the new shell is an augmented
5508 version of the environment that @command{guix environment} was run in.
5509 It contains the necessary search paths for building the given package
5510 added to the existing environment variables. To create a ``pure''
5511 environment, in which the original environment variables have been unset,
5512 use the @code{--pure} option@footnote{Users sometimes wrongfully augment
5513 environment variables such as @code{PATH} in their @file{~/.bashrc}
5514 file. As a consequence, when @code{guix environment} launches it, Bash
5515 may read @file{~/.bashrc}, thereby introducing ``impurities'' in these
5516 environment variables. It is an error to define such environment
5517 variables in @file{.bashrc}; instead, they should be defined in
5518 @file{.bash_profile}, which is sourced only by log-in shells.
5519 @xref{Bash Startup Files,,, bash, The GNU Bash Reference Manual}, for
5520 details on Bash start-up files.}.
5522 @vindex GUIX_ENVIRONMENT
5523 @command{guix environment} defines the @code{GUIX_ENVIRONMENT}
5524 variable in the shell it spawns; its value is the file name of the
5525 profile of this environment. This allows users to, say, define a
5526 specific prompt for development environments in their @file{.bashrc}
5527 (@pxref{Bash Startup Files,,, bash, The GNU Bash Reference Manual}):
5530 if [ -n "$GUIX_ENVIRONMENT" ]
5532 export PS1="\u@@\h \w [dev]\$ "
5537 ... or to browse the profile:
5540 $ ls "$GUIX_ENVIRONMENT/bin"
5543 Additionally, more than one package may be specified, in which case the
5544 union of the inputs for the given packages are used. For example, the
5545 command below spawns a shell where all of the dependencies of both Guile
5546 and Emacs are available:
5549 guix environment guile emacs
5552 Sometimes an interactive shell session is not desired. An arbitrary
5553 command may be invoked by placing the @code{--} token to separate the
5554 command from the rest of the arguments:
5557 guix environment guile -- make -j4
5560 In other situations, it is more convenient to specify the list of
5561 packages needed in the environment. For example, the following command
5562 runs @command{python} from an environment containing Python@tie{}2.7 and
5566 guix environment --ad-hoc python2-numpy python-2.7 -- python
5569 Furthermore, one might want the dependencies of a package and also some
5570 additional packages that are not build-time or runtime dependencies, but
5571 are useful when developing nonetheless. Because of this, the
5572 @code{--ad-hoc} flag is positional. Packages appearing before
5573 @code{--ad-hoc} are interpreted as packages whose dependencies will be
5574 added to the environment. Packages appearing after are interpreted as
5575 packages that will be added to the environment directly. For example,
5576 the following command creates a Guix development environment that
5577 additionally includes Git and strace:
5580 guix environment guix --ad-hoc git strace
5583 Sometimes it is desirable to isolate the environment as much as
5584 possible, for maximal purity and reproducibility. In particular, when
5585 using Guix on a host distro that is not GuixSD, it is desirable to
5586 prevent access to @file{/usr/bin} and other system-wide resources from
5587 the development environment. For example, the following command spawns
5588 a Guile REPL in a ``container'' where only the store and the current
5589 working directory are mounted:
5592 guix environment --ad-hoc --container guile -- guile
5596 The @code{--container} option requires Linux-libre 3.19 or newer.
5599 The available options are summarized below.
5602 @item --expression=@var{expr}
5603 @itemx -e @var{expr}
5604 Create an environment for the package or list of packages that
5605 @var{expr} evaluates to.
5607 For example, running:
5610 guix environment -e '(@@ (gnu packages maths) petsc-openmpi)'
5613 starts a shell with the environment for this specific variant of the
5619 guix environment --ad-hoc -e '(@@ (gnu) %base-packages)'
5622 starts a shell with all the GuixSD base packages available.
5624 The above commands only the use default output of the given packages.
5625 To select other outputs, two element tuples can be specified:
5628 guix environment --ad-hoc -e '(list (@ (gnu packages bash) bash) "include")'
5631 @item --load=@var{file}
5632 @itemx -l @var{file}
5633 Create an environment for the package or list of packages that the code
5634 within @var{file} evaluates to.
5636 As an example, @var{file} might contain a definition like this
5637 (@pxref{Defining Packages}):
5640 @verbatiminclude environment-gdb.scm
5644 Include all specified packages in the resulting environment, as if an
5645 @i{ad hoc} package were defined with them as inputs. This option is
5646 useful for quickly creating an environment without having to write a
5647 package expression to contain the desired inputs.
5649 For instance, the command:
5652 guix environment --ad-hoc guile guile-sdl -- guile
5655 runs @command{guile} in an environment where Guile and Guile-SDL are
5658 Note that this example implicitly asks for the default output of
5659 @code{guile} and @code{guile-sdl}, but it is possible to ask for a
5660 specific output---e.g., @code{glib:bin} asks for the @code{bin} output
5661 of @code{glib} (@pxref{Packages with Multiple Outputs}).
5663 This option may be composed with the default behavior of @command{guix
5664 environment}. Packages appearing before @code{--ad-hoc} are interpreted
5665 as packages whose dependencies will be added to the environment, the
5666 default behavior. Packages appearing after are interpreted as packages
5667 that will be added to the environment directly.
5670 Unset existing environment variables when building the new environment.
5671 This has the effect of creating an environment in which search paths
5672 only contain package inputs.
5674 @item --search-paths
5675 Display the environment variable definitions that make up the
5678 @item --system=@var{system}
5679 @itemx -s @var{system}
5680 Attempt to build for @var{system}---e.g., @code{i686-linux}.
5685 Run @var{command} within an isolated container. The current working
5686 directory outside the container is mapped inside the container.
5687 Additionally, a dummy home directory is created that matches the current
5688 user's home directory, and @file{/etc/passwd} is configured accordingly.
5689 The spawned process runs as the current user outside the container, but
5690 has root privileges in the context of the container.
5694 For containers, share the network namespace with the host system.
5695 Containers created without this flag only have access to the loopback
5698 @item --expose=@var{source}[=@var{target}]
5699 For containers, expose the file system @var{source} from the host system
5700 as the read-only file system @var{target} within the container. If
5701 @var{target} is not specified, @var{source} is used as the target mount
5702 point in the container.
5704 The example below spawns a Guile REPL in a container in which the user's
5705 home directory is accessible read-only via the @file{/exchange}
5709 guix environment --container --expose=$HOME=/exchange guile -- guile
5712 @item --share=@var{source}[=@var{target}]
5713 For containers, share the file system @var{source} from the host system
5714 as the writable file system @var{target} within the container. If
5715 @var{target} is not specified, @var{source} is used as the target mount
5716 point in the container.
5718 The example below spawns a Guile REPL in a container in which the user's
5719 home directory is accessible for both reading and writing via the
5720 @file{/exchange} directory:
5723 guix environment --container --share=$HOME=/exchange guile -- guile
5727 It also supports all of the common build options that @command{guix
5728 build} supports (@pxref{Common Build Options}).
5730 @node Invoking guix publish
5731 @section Invoking @command{guix publish}
5733 The purpose of @command{guix publish} is to enable users to easily share
5734 their store with others, who can then use it as a substitute server
5735 (@pxref{Substitutes}).
5737 When @command{guix publish} runs, it spawns an HTTP server which allows
5738 anyone with network access to obtain substitutes from it. This means
5739 that any machine running Guix can also act as if it were a build farm,
5740 since the HTTP interface is compatible with Hydra, the software behind
5741 the @code{hydra.gnu.org} build farm.
5743 For security, each substitute is signed, allowing recipients to check
5744 their authenticity and integrity (@pxref{Substitutes}). Because
5745 @command{guix publish} uses the signing key of the system, which is only
5746 readable by the system administrator, it must be started as root; the
5747 @code{--user} option makes it drop root privileges early on.
5749 The signing key pair must be generated before @command{guix publish} is
5750 launched, using @command{guix archive --generate-key} (@pxref{Invoking
5753 The general syntax is:
5756 guix publish @var{options}@dots{}
5759 Running @command{guix publish} without any additional arguments will
5760 spawn an HTTP server on port 8080:
5766 Once a publishing server has been authorized (@pxref{Invoking guix
5767 archive}), the daemon may download substitutes from it:
5770 guix-daemon --substitute-urls=http://example.org:8080
5773 As a bonus, @command{guix publish} also serves as a content-addressed
5774 mirror for source files referenced in @code{origin} records
5775 (@pxref{origin Reference}). For instance, assuming @command{guix
5776 publish} is running on @code{example.org}, the following URL returns the
5777 raw @file{hello-2.10.tar.gz} file with the given SHA256 hash
5778 (represented in @code{nix-base32} format, @pxref{Invoking guix hash}):
5781 http://example.org/file/hello-2.10.tar.gz/sha256/0ssi1@dots{}ndq1i
5784 Obviously, these URLs only work for files that are in the store; in
5785 other cases, they return 404 (``Not Found'').
5787 The following options are available:
5790 @item --port=@var{port}
5791 @itemx -p @var{port}
5792 Listen for HTTP requests on @var{port}.
5794 @item --listen=@var{host}
5795 Listen on the network interface for @var{host}. The default is to
5796 accept connections from any interface.
5798 @item --user=@var{user}
5799 @itemx -u @var{user}
5800 Change privileges to @var{user} as soon as possible---i.e., once the
5801 server socket is open and the signing key has been read.
5803 @item --compression[=@var{level}]
5804 @itemx -C [@var{level}]
5805 Compress data using the given @var{level}. When @var{level} is zero,
5806 disable compression. The range 1 to 9 corresponds to different gzip
5807 compression levels: 1 is the fastest, and 9 is the best (CPU-intensive).
5810 Compression occurs on the fly and the compressed streams are not
5811 cached. Thus, to reduce load on the machine that runs @command{guix
5812 publish}, it may be a good idea to choose a low compression level, or to
5813 run @command{guix publish} behind a caching proxy.
5815 @item --ttl=@var{ttl}
5816 Produce @code{Cache-Control} HTTP headers that advertise a time-to-live
5817 (TTL) of @var{ttl}. @var{ttl} must denote a duration: @code{5d} means 5
5818 days, @code{1m} means 1 month, and so on.
5820 This allows the user's Guix to keep substitute information in cache for
5821 @var{ttl}. However, note that @code{guix publish} does not itself
5822 guarantee that the store items it provides will indeed remain available
5823 for as long as @var{ttl}.
5825 @item --repl[=@var{port}]
5826 @itemx -r [@var{port}]
5827 Spawn a Guile REPL server (@pxref{REPL Servers,,, guile, GNU Guile
5828 Reference Manual}) on @var{port} (37146 by default). This is used
5829 primarily for debugging a running @command{guix publish} server.
5832 Enabling @command{guix publish} on a GuixSD system is a one-liner: just
5833 add a call to @code{guix-publish-service} in the @code{services} field
5834 of the @code{operating-system} declaration (@pxref{guix-publish-service,
5835 @code{guix-publish-service}}).
5838 @node Invoking guix challenge
5839 @section Invoking @command{guix challenge}
5841 @cindex reproducible builds
5842 @cindex verifiable builds
5844 Do the binaries provided by this server really correspond to the source
5845 code it claims to build? Is a package build process deterministic?
5846 These are the questions the @command{guix challenge} command attempts to
5849 The former is obviously an important question: Before using a substitute
5850 server (@pxref{Substitutes}), one had better @emph{verify} that it
5851 provides the right binaries, and thus @emph{challenge} it. The latter
5852 is what enables the former: If package builds are deterministic, then
5853 independent builds of the package should yield the exact same result,
5854 bit for bit; if a server provides a binary different from the one
5855 obtained locally, it may be either corrupt or malicious.
5857 We know that the hash that shows up in @file{/gnu/store} file names is
5858 the hash of all the inputs of the process that built the file or
5859 directory---compilers, libraries, build scripts,
5860 etc. (@pxref{Introduction}). Assuming deterministic build processes,
5861 one store file name should map to exactly one build output.
5862 @command{guix challenge} checks whether there is, indeed, a single
5863 mapping by comparing the build outputs of several independent builds of
5864 any given store item.
5866 The command output looks like this:
5869 $ guix challenge --substitute-urls="https://hydra.gnu.org https://guix.example.org"
5870 updating list of substitutes from 'https://hydra.gnu.org'... 100.0%
5871 updating list of substitutes from 'https://guix.example.org'... 100.0%
5872 /gnu/store/@dots{}-openssl-1.0.2d contents differ:
5873 local hash: 0725l22r5jnzazaacncwsvp9kgf42266ayyp814v7djxs7nk963q
5874 https://hydra.gnu.org/nar/@dots{}-openssl-1.0.2d: 0725l22r5jnzazaacncwsvp9kgf42266ayyp814v7djxs7nk963q
5875 https://guix.example.org/nar/@dots{}-openssl-1.0.2d: 1zy4fmaaqcnjrzzajkdn3f5gmjk754b43qkq47llbyak9z0qjyim
5876 /gnu/store/@dots{}-git-2.5.0 contents differ:
5877 local hash: 00p3bmryhjxrhpn2gxs2fy0a15lnip05l97205pgbk5ra395hyha
5878 https://hydra.gnu.org/nar/@dots{}-git-2.5.0: 069nb85bv4d4a6slrwjdy8v1cn4cwspm3kdbmyb81d6zckj3nq9f
5879 https://guix.example.org/nar/@dots{}-git-2.5.0: 0mdqa9w1p6cmli6976v4wi0sw9r4p5prkj7lzfd1877wk11c9c73
5880 /gnu/store/@dots{}-pius-2.1.1 contents differ:
5881 local hash: 0k4v3m9z1zp8xzzizb7d8kjj72f9172xv078sq4wl73vnq9ig3ax
5882 https://hydra.gnu.org/nar/@dots{}-pius-2.1.1: 0k4v3m9z1zp8xzzizb7d8kjj72f9172xv078sq4wl73vnq9ig3ax
5883 https://guix.example.org/nar/@dots{}-pius-2.1.1: 1cy25x1a4fzq5rk0pmvc8xhwyffnqz95h2bpvqsz2mpvlbccy0gs
5887 In this example, @command{guix challenge} first scans the store to
5888 determine the set of locally-built derivations---as opposed to store
5889 items that were downloaded from a substitute server---and then queries
5890 all the substitute servers. It then reports those store items for which
5891 the servers obtained a result different from the local build.
5893 @cindex non-determinism, in package builds
5894 As an example, @code{guix.example.org} always gets a different answer.
5895 Conversely, @code{hydra.gnu.org} agrees with local builds, except in the
5896 case of Git. This might indicate that the build process of Git is
5897 non-deterministic, meaning that its output varies as a function of
5898 various things that Guix does not fully control, in spite of building
5899 packages in isolated environments (@pxref{Features}). Most common
5900 sources of non-determinism include the addition of timestamps in build
5901 results, the inclusion of random numbers, and directory listings sorted
5902 by inode number. See @uref{https://reproducible-builds.org/docs/}, for
5905 To find out what is wrong with this Git binary, we can do something along
5906 these lines (@pxref{Invoking guix archive}):
5909 $ wget -q -O - https://hydra.gnu.org/nar/@dots{}-git-2.5.0 \
5910 | guix archive -x /tmp/git
5911 $ diff -ur --no-dereference /gnu/store/@dots{}-git.2.5.0 /tmp/git
5914 This command shows the difference between the files resulting from the
5915 local build, and the files resulting from the build on
5916 @code{hydra.gnu.org} (@pxref{Overview, Comparing and Merging Files,,
5917 diffutils, Comparing and Merging Files}). The @command{diff} command
5918 works great for text files. When binary files differ, a better option
5919 is @uref{https://diffoscope.org/, Diffoscope}, a tool that helps
5920 visualize differences for all kinds of files.
5922 Once you have done that work, you can tell whether the differences are due
5923 to a non-deterministic build process or to a malicious server. We try
5924 hard to remove sources of non-determinism in packages to make it easier
5925 to verify substitutes, but of course, this is a process that
5926 involves not just Guix, but a large part of the free software community.
5927 In the meantime, @command{guix challenge} is one tool to help address
5930 If you are writing packages for Guix, you are encouraged to check
5931 whether @code{hydra.gnu.org} and other substitute servers obtain the
5932 same build result as you did with:
5935 $ guix challenge @var{package}
5939 where @var{package} is a package specification such as
5940 @code{guile@@2.0} or @code{glibc:debug}.
5942 The general syntax is:
5945 guix challenge @var{options} [@var{packages}@dots{}]
5948 When a difference is found between the hash of a locally-built item and
5949 that of a server-provided substitute, or among substitutes provided by
5950 different servers, the command displays it as in the example above and
5951 its exit code is 2 (other non-zero exit codes denote other kinds of
5954 The one option that matters is:
5958 @item --substitute-urls=@var{urls}
5959 Consider @var{urls} the whitespace-separated list of substitute source
5965 @node Invoking guix container
5966 @section Invoking @command{guix container}
5970 As of version @value{VERSION}, this tool is experimental. The interface
5971 is subject to radical change in the future.
5974 The purpose of @command{guix container} is to manipulate processes
5975 running within an isolated environment, commonly known as a
5976 ``container'', typically created by the @command{guix environment}
5977 (@pxref{Invoking guix environment}) and @command{guix system container}
5978 (@pxref{Invoking guix system}) commands.
5980 The general syntax is:
5983 guix container @var{action} @var{options}@dots{}
5986 @var{action} specifies the operation to perform with a container, and
5987 @var{options} specifies the context-specific arguments for the action.
5989 The following actions are available:
5993 Execute a command within the context of a running container.
5998 guix container exec @var{pid} @var{program} @var{arguments}@dots{}
6001 @var{pid} specifies the process ID of the running container.
6002 @var{program} specifies an executable file name within the root file
6003 system of the container. @var{arguments} are the additional options that
6004 will be passed to @var{program}.
6006 The following command launches an interactive login shell inside a
6007 GuixSD container, started by @command{guix system container}, and whose
6011 guix container exec 9001 /run/current-system/profile/bin/bash --login
6014 Note that the @var{pid} cannot be the parent process of a container. It
6015 must be PID 1 of the container or one of its child processes.
6019 @c *********************************************************************
6020 @node GNU Distribution
6021 @chapter GNU Distribution
6023 @cindex Guix System Distribution
6025 Guix comes with a distribution of the GNU system consisting entirely of
6026 free software@footnote{The term ``free'' here refers to the
6027 @url{http://www.gnu.org/philosophy/free-sw.html,freedom provided to
6028 users of that software}.}. The
6029 distribution can be installed on its own (@pxref{System Installation}),
6030 but it is also possible to install Guix as a package manager on top of
6031 an installed GNU/Linux system (@pxref{Installation}). To distinguish
6032 between the two, we refer to the standalone distribution as the Guix
6033 System Distribution, or GuixSD.
6035 The distribution provides core GNU packages such as GNU libc, GCC, and
6036 Binutils, as well as many GNU and non-GNU applications. The complete
6037 list of available packages can be browsed
6038 @url{http://www.gnu.org/software/guix/packages,on-line} or by
6039 running @command{guix package} (@pxref{Invoking guix package}):
6042 guix package --list-available
6045 Our goal is to provide a practical 100% free software distribution of
6046 Linux-based and other variants of GNU, with a focus on the promotion and
6047 tight integration of GNU components, and an emphasis on programs and
6048 tools that help users exert that freedom.
6050 Packages are currently available on the following platforms:
6055 Intel/AMD @code{x86_64} architecture, Linux-Libre kernel;
6058 Intel 32-bit architecture (IA32), Linux-Libre kernel;
6061 ARMv7-A architecture with hard float, Thumb-2 and NEON,
6062 using the EABI hard-float application binary interface (ABI),
6063 and Linux-Libre kernel.
6065 @item mips64el-linux
6066 little-endian 64-bit MIPS processors, specifically the Loongson series,
6067 n32 ABI, and Linux-Libre kernel.
6071 GuixSD itself is currently only available on @code{i686} and @code{x86_64}.
6074 For information on porting to other architectures or kernels,
6078 * System Installation:: Installing the whole operating system.
6079 * System Configuration:: Configuring the operating system.
6080 * Installing Debugging Files:: Feeding the debugger.
6081 * Security Updates:: Deploying security fixes quickly.
6082 * Package Modules:: Packages from the programmer's viewpoint.
6083 * Packaging Guidelines:: Growing the distribution.
6084 * Bootstrapping:: GNU/Linux built from scratch.
6085 * Porting:: Targeting another platform or kernel.
6088 Building this distribution is a cooperative effort, and you are invited
6089 to join! @xref{Contributing}, for information about how you can help.
6091 @node System Installation
6092 @section System Installation
6094 @cindex Guix System Distribution
6095 This section explains how to install the Guix System Distribution (GuixSD)
6096 on a machine. The Guix package manager can
6097 also be installed on top of a running GNU/Linux system,
6098 @pxref{Installation}.
6102 @c This paragraph is for people reading this from tty2 of the
6103 @c installation image.
6104 You are reading this documentation with an Info reader. For details on
6105 how to use it, hit the @key{RET} key (``return'' or ``enter'') on the
6106 link that follows: @pxref{Top, Info reader,, info-stnd, Stand-alone GNU
6107 Info}. Hit @kbd{l} afterwards to come back here.
6109 Alternately, run @command{info info} in another tty to keep the manual
6115 * Limitations:: What you can expect.
6116 * Hardware Considerations:: Supported hardware.
6117 * USB Stick Installation:: Preparing the installation medium.
6118 * Preparing for Installation:: Networking, partitioning, etc.
6119 * Proceeding with the Installation:: The real thing.
6120 * Installing GuixSD in a VM:: GuixSD playground.
6121 * Building the Installation Image:: How this comes to be.
6125 @subsection Limitations
6127 As of version @value{VERSION}, the Guix System Distribution (GuixSD) is
6128 not production-ready. It may contain bugs and lack important
6129 features. Thus, if you are looking for a stable production system that
6130 respects your freedom as a computer user, a good solution at this point
6131 is to consider @url{http://www.gnu.org/distros/free-distros.html, one of
6132 the more established GNU/Linux distributions}. We hope you can soon switch
6133 to the GuixSD without fear, of course. In the meantime, you can
6134 also keep using your distribution and try out the package manager on top
6135 of it (@pxref{Installation}).
6137 Before you proceed with the installation, be aware of the following
6138 noteworthy limitations applicable to version @value{VERSION}:
6142 The installation process does not include a graphical user interface and
6143 requires familiarity with GNU/Linux (see the following subsections to
6144 get a feel of what that means.)
6147 Support for the Logical Volume Manager (LVM) is missing.
6150 Few system services are currently supported out-of-the-box
6154 More than 3,200 packages are available, but you may
6155 occasionally find that a useful package is missing.
6158 GNOME, Xfce, and Enlightenment are available (@pxref{Desktop Services}),
6159 as well as a number of X11 window managers. However, some graphical
6160 applications may be missing, as well as KDE.
6163 You have been warned! But more than a disclaimer, this is an invitation
6164 to report issues (and success stories!), and to join us in improving it.
6165 @xref{Contributing}, for more info.
6168 @node Hardware Considerations
6169 @subsection Hardware Considerations
6171 @cindex hardware support on GuixSD
6172 GNU@tie{}GuixSD focuses on respecting the user's computing freedom. It
6173 builds around the kernel Linux-libre, which means that only hardware for
6174 which free software drivers and firmware exist is supported. Nowadays,
6175 a wide range of off-the-shelf hardware is supported on
6176 GNU/Linux-libre---from keyboards to graphics cards to scanners and
6177 Ethernet controllers. Unfortunately, there are still areas where
6178 hardware vendors deny users control over their own computing, and such
6179 hardware is not supported on GuixSD.
6181 @cindex WiFi, hardware support
6182 One of the main areas where free drivers or firmware are lacking is WiFi
6183 devices. WiFi devices known to work include those using Atheros chips
6184 (AR9271 and AR7010), which corresponds to the @code{ath9k} Linux-libre
6185 driver, and for which free firmware exists and is available
6186 out-of-the-box on GuixSD, as part of @var{%base-firmware}
6187 (@pxref{operating-system Reference, @code{firmware}}).
6189 @cindex RYF, Respects Your Freedom
6190 The @uref{https://www.fsf.org/, Free Software Foundation} runs
6191 @uref{https://www.fsf.org/ryf, @dfn{Respects Your Freedom}} (RYF), a
6192 certification program for hardware products that respect your freedom
6193 and your privacy and ensure that you have control over your device. We
6194 encourage you to check the list of RYF-certified devices.
6196 Another useful resource is the @uref{https://www.h-node.org/, H-Node}
6197 web site. It contains a catalog of hardware devices with information
6198 about their support in GNU/Linux.
6201 @node USB Stick Installation
6202 @subsection USB Stick Installation
6204 An installation image for USB sticks can be downloaded from
6205 @indicateurl{ftp://alpha.gnu.org/gnu/guix/guixsd-usb-install-@value{VERSION}.@var{system}.xz},
6206 where @var{system} is one of:
6210 for a GNU/Linux system on Intel/AMD-compatible 64-bit CPUs;
6213 for a 32-bit GNU/Linux system on Intel-compatible CPUs.
6216 @c start duplication of authentication part from ``Binary Installation''
6217 Make sure to download the associated @file{.sig} file and to verify the
6218 authenticity of the image against it, along these lines:
6221 $ wget ftp://alpha.gnu.org/gnu/guix/guixsd-usb-install-@value{VERSION}.@var{system}.xz.sig
6222 $ gpg --verify guixsd-usb-install-@value{VERSION}.@var{system}.xz.sig
6225 If that command fails because you do not have the required public key,
6226 then run this command to import it:
6229 $ gpg --keyserver pgp.mit.edu --recv-keys @value{OPENPGP-SIGNING-KEY-ID}
6233 and rerun the @code{gpg --verify} command.
6236 This image contains a single partition with the tools necessary for an
6237 installation. It is meant to be copied @emph{as is} to a large-enough
6240 To copy the image to a USB stick, follow these steps:
6244 Decompress the image using the @command{xz} command:
6247 xz -d guixsd-usb-install-@value{VERSION}.@var{system}.xz
6251 Insert a USB stick of 1@tie{}GiB or more into your machine, and determine
6252 its device name. Assuming that the USB stick is known as @file{/dev/sdX},
6253 copy the image with:
6256 dd if=guixsd-usb-install-@value{VERSION}.x86_64 of=/dev/sdX
6259 Access to @file{/dev/sdX} usually requires root privileges.
6262 Once this is done, you should be able to reboot the system and boot from
6263 the USB stick. The latter usually requires you to get in the BIOS' boot
6264 menu, where you can choose to boot from the USB stick.
6266 @xref{Installing GuixSD in a VM}, if, instead, you would like to install
6267 GuixSD in a virtual machine (VM).
6269 @node Preparing for Installation
6270 @subsection Preparing for Installation
6272 Once you have successfully booted the image on the USB stick, you should
6273 end up with a root prompt. Several console TTYs are configured and can
6274 be used to run commands as root. TTY2 shows this documentation,
6275 browsable using the Info reader commands (@pxref{Top,,, info-stnd,
6276 Stand-alone GNU Info}). The installation system runs the GPM mouse
6277 daemon, which allows you to select text with the left mouse button and
6278 to paste it with the middle button.
6281 Installation requires access to the Internet so that any missing
6282 dependencies of your system configuration can be downloaded. See the
6283 ``Networking'' section below.
6286 The installation system includes many common tools needed for this task.
6287 But it is also a full-blown GuixSD system, which means that you can
6288 install additional packages, should you need it, using @command{guix
6289 package} (@pxref{Invoking guix package}).
6291 @subsubsection Keyboard Layout
6293 @cindex keyboard layout
6294 The installation image uses the US qwerty keyboard layout. If you want
6295 to change it, you can use the @command{loadkeys} command. For example,
6296 the following command selects the Dvorak keyboard layout:
6302 See the files under @file{/run/current-system/profile/share/keymaps} for
6303 a list of available keyboard layouts. Run @command{man loadkeys} for
6306 @subsubsection Networking
6308 Run the following command see what your network interfaces are called:
6315 @dots{} or, using the GNU/Linux-specific @command{ip} command:
6321 @c http://cgit.freedesktop.org/systemd/systemd/tree/src/udev/udev-builtin-net_id.c#n20
6322 Wired interfaces have a name starting with @samp{e}; for example, the
6323 interface corresponding to the first on-board Ethernet controller is
6324 called @samp{eno1}. Wireless interfaces have a name starting with
6325 @samp{w}, like @samp{w1p2s0}.
6328 @item Wired connection
6329 To configure a wired network run the following command, substituting
6330 @var{interface} with the name of the wired interface you want to use.
6333 ifconfig @var{interface} up
6336 @item Wireless connection
6337 To configure wireless networking, you can create a configuration file
6338 for the @command{wpa_supplicant} configuration tool (its location is not
6339 important) using one of the available text editors such as
6343 zile wpa_supplicant.conf
6346 As an example, the following stanza can go to this file and will work
6347 for many wireless networks, provided you give the actual SSID and
6348 passphrase for the network you are connecting to:
6352 ssid="@var{my-ssid}"
6354 psk="the network's secret passphrase"
6358 Start the wireless service and run it in the background with the
6359 following command (substitute @var{interface} with the name of the
6360 network interface you want to use):
6363 wpa_supplicant -c wpa_supplicant.conf -i @var{interface} -B
6366 Run @command{man wpa_supplicant} for more information.
6369 At this point, you need to acquire an IP address. On a network where IP
6370 addresses are automatically assigned @i{via} DHCP, you can run:
6373 dhclient -v @var{interface}
6376 Try to ping a server to see if networking is up and running:
6382 Setting up network access is almost always a requirement because the
6383 image does not contain all the software and tools that may be needed.
6385 @subsubsection Disk Partitioning
6387 Unless this has already been done, the next step is to partition, and
6388 then format the target partition(s).
6390 The installation image includes several partitioning tools, including
6391 Parted (@pxref{Overview,,, parted, GNU Parted User Manual}),
6392 @command{fdisk}, and @command{cfdisk}. Run it and set up your disk with
6393 the partition layout you want:
6399 Once you are done partitioning the target hard disk drive, you have to
6400 create a file system on the relevant partition(s)@footnote{Currently
6401 GuixSD pretty much assumes an ext4 file system. In particular, code
6402 that reads partition UUIDs and labels only works with ext4. This will
6403 be fixed in the future.}.
6405 Preferably, assign partitions a label so that you can easily and
6406 reliably refer to them in @code{file-system} declarations (@pxref{File
6407 Systems}). This is typically done using the @code{-L} option of
6408 @command{mkfs.ext4} and related commands. So, assuming the target root
6409 partition lives at @file{/dev/sda1}, a file system with the label
6410 @code{my-root} can be created with:
6413 mkfs.ext4 -L my-root /dev/sda1
6416 @c FIXME: Uncomment this once GRUB fully supports encrypted roots.
6417 @c A typical command sequence may be:
6421 @c @dots{} Create partitions etc.@dots{}
6422 @c # cryptsetup luksFormat /dev/sdX1
6423 @c # cryptsetup open --type luks /dev/sdX1 my-partition
6424 @c # mkfs.ext4 -L my-root /dev/mapper/my-partition
6427 In addition to e2fsprogs, the suite of tools to manipulate
6428 ext2/ext3/ext4 file systems, the installation image includes
6429 Cryptsetup/LUKS for disk encryption.
6431 Once that is done, mount the target root partition under @file{/mnt}
6432 with a command like (again, assuming @file{/dev/sda1} is the root
6436 mount /dev/sda1 /mnt
6439 Finally, if you plan to use one or more swap partitions (@pxref{Memory
6440 Concepts, swap space,, libc, The GNU C Library Reference Manual}), make
6441 sure to initialize them with @command{mkswap}. Assuming you have one
6442 swap partition on @file{/dev/sda2}, you would run:
6448 @node Proceeding with the Installation
6449 @subsection Proceeding with the Installation
6451 With the target partitions ready and the target root mounted on
6452 @file{/mnt}, we're ready to go. First, run:
6455 herd start cow-store /mnt
6458 This makes @file{/gnu/store} copy-on-write, such that packages added to it
6459 during the installation phase are written to the target disk on @file{/mnt}
6460 rather than kept in memory. This is necessary because the first phase of
6461 the @command{guix system init} command (see below) entails downloads or
6462 builds to @file{/gnu/store} which, initially, is an in-memory file system.
6464 Next, you have to edit a file and
6465 provide the declaration of the operating system to be installed. To
6466 that end, the installation system comes with three text editors: GNU nano
6467 (@pxref{Top,,, nano, GNU nano Manual}), GNU Zile (an Emacs clone), and
6468 nvi (a clone of the original BSD @command{vi} editor).
6469 We strongly recommend storing that file on the target root file system, say,
6470 as @file{/mnt/etc/config.scm}. Failing to do that, you will have lost your
6471 configuration file once you have rebooted into the newly-installed system.
6473 @xref{Using the Configuration System}, for an overview of the
6474 configuration file. The example configurations discussed in that
6475 section are available under @file{/etc/configuration} in the
6476 installation image. Thus, to get started with a system configuration
6477 providing a graphical display server (a ``desktop'' system), you can run
6478 something along these lines:
6482 # cp /etc/configuration/desktop.scm /mnt/etc/config.scm
6483 # zile /mnt/etc/config.scm
6486 You should pay attention to what your configuration file contains, and
6491 Make sure the @code{grub-configuration} form refers to the device you
6492 want to install GRUB on.
6495 Be sure that your partition labels match the value of their respective
6496 @code{device} fields in your @code{file-system} configuration, assuming
6497 your @code{file-system} configuration sets the value of @code{title} to
6501 Once you are done preparing the configuration file, the new system must
6502 be initialized (remember that the target root file system is mounted
6506 guix system init /mnt/etc/config.scm /mnt
6510 This copies all the necessary files and installs GRUB on
6511 @file{/dev/sdX}, unless you pass the @option{--no-grub} option. For
6512 more information, @pxref{Invoking guix system}. This command may trigger
6513 downloads or builds of missing packages, which can take some time.
6515 Once that command has completed---and hopefully succeeded!---you can run
6516 @command{reboot} and boot into the new system. The @code{root} password
6517 in the new system is initially empty; other users' passwords need to be
6518 initialized by running the @command{passwd} command as @code{root},
6519 unless your configuration specifies otherwise
6520 (@pxref{user-account-password, user account passwords}).
6522 Join us on @code{#guix} on the Freenode IRC network or on
6523 @file{guix-devel@@gnu.org} to share your experience---good or not so
6526 @node Installing GuixSD in a VM
6527 @subsection Installing GuixSD in a Virtual Machine
6529 @cindex virtual machine, GuixSD installation
6530 If you'd like to install GuixSD in a virtual machine (VM) rather than on
6531 your beloved machine, this section is for you.
6533 To boot a @uref{http://qemu.org/,QEMU} VM for installing GuixSD in a
6534 disk image, follow these steps:
6538 First, retrieve the GuixSD installation image as described previously
6539 (@pxref{USB Stick Installation}).
6542 Create a disk image that will hold the installed system. To make a
6543 qcow2-formatted disk image, use the @command{qemu-img} command:
6546 qemu-img create -f qcow2 guixsd.img 5G
6549 This will create a 5GB file.
6552 Boot the USB installation image in an VM:
6555 qemu-system-x86_64 -m 1024 -smp 1 \
6556 -net default -net nic,model=virtio -boot menu=on \
6557 -drive file=guixsd.img \
6558 -drive file=guixsd-usb-install-@value{VERSION}.@var{system}
6561 In the VM console, quickly press the @kbd{F12} key to enter the boot
6562 menu. Then press the @kbd{2} key and the @kbd{RET} key to validate your
6566 You're now root in the VM, proceed with the installation process.
6567 @xref{Preparing for Installation}, and follow the instructions.
6570 Once installation is complete, you can boot the system that's on your
6571 @file{guixsd.img} image. @xref{Running GuixSD in a VM}, for how to do
6574 @node Building the Installation Image
6575 @subsection Building the Installation Image
6577 The installation image described above was built using the @command{guix
6578 system} command, specifically:
6580 @c FIXME: 1G is too much; see <http://bugs.gnu.org/23077>.
6582 guix system disk-image --image-size=1G gnu/system/install.scm
6585 Have a look at @file{gnu/system/install.scm} in the source tree,
6586 and see also @ref{Invoking guix system} for more information
6587 about the installation image.
6589 @node System Configuration
6590 @section System Configuration
6592 @cindex system configuration
6593 The Guix System Distribution supports a consistent whole-system configuration
6594 mechanism. By that we mean that all aspects of the global system
6595 configuration---such as the available system services, timezone and
6596 locale settings, user accounts---are declared in a single place. Such
6597 a @dfn{system configuration} can be @dfn{instantiated}---i.e., effected.
6599 One of the advantages of putting all the system configuration under the
6600 control of Guix is that it supports transactional system upgrades, and
6601 makes it possible to roll back to a previous system instantiation,
6602 should something go wrong with the new one (@pxref{Features}). Another
6603 advantage is that it makes it easy to replicate the exact same configuration
6604 across different machines, or at different points in time, without
6605 having to resort to additional administration tools layered on top of
6606 the own tools of the system.
6607 @c Yes, we're talking of Puppet, Chef, & co. here. ↑
6609 This section describes this mechanism. First we focus on the system
6610 administrator's viewpoint---explaining how the system is configured and
6611 instantiated. Then we show how this mechanism can be extended, for
6612 instance to support new system services.
6615 * Using the Configuration System:: Customizing your GNU system.
6616 * operating-system Reference:: Detail of operating-system declarations.
6617 * File Systems:: Configuring file system mounts.
6618 * Mapped Devices:: Block device extra processing.
6619 * User Accounts:: Specifying user accounts.
6620 * Locales:: Language and cultural convention settings.
6621 * Services:: Specifying system services.
6622 * Setuid Programs:: Programs running with root privileges.
6623 * X.509 Certificates:: Authenticating HTTPS servers.
6624 * Name Service Switch:: Configuring libc's name service switch.
6625 * Initial RAM Disk:: Linux-Libre bootstrapping.
6626 * GRUB Configuration:: Configuring the boot loader.
6627 * Invoking guix system:: Instantiating a system configuration.
6628 * Running GuixSD in a VM:: How to run GuixSD in a virtual machine.
6629 * Defining Services:: Adding new service definitions.
6632 @node Using the Configuration System
6633 @subsection Using the Configuration System
6635 The operating system is configured by providing an
6636 @code{operating-system} declaration in a file that can then be passed to
6637 the @command{guix system} command (@pxref{Invoking guix system}). A
6638 simple setup, with the default system services, the default Linux-Libre
6639 kernel, initial RAM disk, and boot loader looks like this:
6641 @findex operating-system
6643 @include os-config-bare-bones.texi
6646 This example should be self-describing. Some of the fields defined
6647 above, such as @code{host-name} and @code{bootloader}, are mandatory.
6648 Others, such as @code{packages} and @code{services}, can be omitted, in
6649 which case they get a default value.
6651 Below we discuss the effect of some of the most important fields
6652 (@pxref{operating-system Reference}, for details about all the available
6653 fields), and how to @dfn{instantiate} the operating system using
6654 @command{guix system}.
6656 @unnumberedsubsubsec Globally-Visible Packages
6658 @vindex %base-packages
6659 The @code{packages} field lists packages that will be globally visible
6660 on the system, for all user accounts---i.e., in every user's @code{PATH}
6661 environment variable---in addition to the per-user profiles
6662 (@pxref{Invoking guix package}). The @var{%base-packages} variable
6663 provides all the tools one would expect for basic user and administrator
6664 tasks---including the GNU Core Utilities, the GNU Networking Utilities,
6665 the GNU Zile lightweight text editor, @command{find}, @command{grep},
6666 etc. The example above adds tcpdump to those, taken from the @code{(gnu
6667 packages admin)} module (@pxref{Package Modules}).
6669 @findex specification->package
6670 Referring to packages by variable name, like @var{tcpdump} above, has
6671 the advantage of being unambiguous; it also allows typos and such to be
6672 diagnosed right away as ``unbound variables''. The downside is that one
6673 needs to know which module defines which package, and to augment the
6674 @code{use-package-modules} line accordingly. To avoid that, one can use
6675 the @code{specification->package} procedure of the @code{(gnu packages)}
6676 module, which returns the best package for a given name or name and
6680 (use-modules (gnu packages))
6684 (packages (append (map specification->package
6685 '("tcpdump" "htop" "gnupg@@2.0"))
6689 @unnumberedsubsubsec System Services
6691 @vindex %base-services
6692 The @code{services} field lists @dfn{system services} to be made
6693 available when the system starts (@pxref{Services}).
6694 The @code{operating-system} declaration above specifies that, in
6695 addition to the basic services, we want the @command{lshd} secure shell
6696 daemon listening on port 2222 (@pxref{Networking Services,
6697 @code{lsh-service}}). Under the hood,
6698 @code{lsh-service} arranges so that @code{lshd} is started with the
6699 right command-line options, possibly with supporting configuration files
6700 generated as needed (@pxref{Defining Services}).
6702 @cindex customization, of services
6703 @findex modify-services
6704 Occasionally, instead of using the base services as is, you will want to
6705 customize them. To do this, use @code{modify-services} (@pxref{Service
6706 Reference, @code{modify-services}}) to modify the list.
6708 For example, suppose you want to modify @code{guix-daemon} and Mingetty
6709 (the console log-in) in the @var{%base-services} list (@pxref{Base
6710 Services, @code{%base-services}}). To do that, you can write the
6711 following in your operating system declaration:
6714 (define %my-services
6715 ;; My very own list of services.
6716 (modify-services %base-services
6717 (guix-service-type config =>
6720 (use-substitutes? #f)
6721 (extra-options '("--gc-keep-derivations"))))
6722 (mingetty-service-type config =>
6723 (mingetty-configuration
6725 (motd (plain-file "motd" "Howdy!"))))))
6729 (services %my-services))
6732 This changes the configuration---i.e., the service parameters---of the
6733 @code{guix-service-type} instance, and that of all the
6734 @code{mingetty-service-type} instances in the @var{%base-services} list.
6735 Observe how this is accomplished: first, we arrange for the original
6736 configuration to be bound to the identifier @code{config} in the
6737 @var{body}, and then we write the @var{body} so that it evaluates to the
6738 desired configuration. In particular, notice how we use @code{inherit}
6739 to create a new configuration which has the same values as the old
6740 configuration, but with a few modifications.
6742 The configuration for a typical ``desktop'' usage, with the X11 display
6743 server, GNOME and Xfce (users can choose which of these desktop
6744 environments to use at the log-in screen by pressing @kbd{F1}), network
6745 management, power management, and more, would look like this:
6748 @include os-config-desktop.texi
6751 A graphical environment with a choice of lightweight window managers
6752 instead of full-blown desktop environments would look like this:
6755 @include os-config-lightweight-desktop.texi
6758 @xref{Desktop Services}, for the exact list of services provided by
6759 @var{%desktop-services}. @xref{X.509 Certificates}, for background
6760 information about the @code{nss-certs} package that is used here.
6762 Again, @var{%desktop-services} is just a list of service objects. If
6763 you want to remove services from there, you can do so using the
6764 procedures for list filtering (@pxref{SRFI-1 Filtering and
6765 Partitioning,,, guile, GNU Guile Reference Manual}). For instance, the
6766 following expression returns a list that contains all the services in
6767 @var{%desktop-services} minus the Avahi service:
6770 (remove (lambda (service)
6771 (eq? (service-kind service) avahi-service-type))
6775 @unnumberedsubsubsec Instantiating the System
6777 Assuming the @code{operating-system} declaration
6778 is stored in the @file{my-system-config.scm}
6779 file, the @command{guix system reconfigure my-system-config.scm} command
6780 instantiates that configuration, and makes it the default GRUB boot
6781 entry (@pxref{Invoking guix system}).
6783 The normal way to change the system configuration is by updating this
6784 file and re-running @command{guix system reconfigure}. One should never
6785 have to touch files in @command{/etc} or to run commands that modify the
6786 system state such as @command{useradd} or @command{grub-install}. In
6787 fact, you must avoid that since that would not only void your warranty
6788 but also prevent you from rolling back to previous versions of your
6789 system, should you ever need to.
6791 @cindex roll-back, of the operating system
6792 Speaking of roll-back, each time you run @command{guix system
6793 reconfigure}, a new @dfn{generation} of the system is created---without
6794 modifying or deleting previous generations. Old system generations get
6795 an entry in the GRUB boot menu, allowing you to boot them in case
6796 something went wrong with the latest generation. Reassuring, no? The
6797 @command{guix system list-generations} command lists the system
6798 generations available on disk.
6800 @unnumberedsubsubsec The Programming Interface
6802 At the Scheme level, the bulk of an @code{operating-system} declaration
6803 is instantiated with the following monadic procedure (@pxref{The Store
6806 @deffn {Monadic Procedure} operating-system-derivation os
6807 Return a derivation that builds @var{os}, an @code{operating-system}
6808 object (@pxref{Derivations}).
6810 The output of the derivation is a single directory that refers to all
6811 the packages, configuration files, and other supporting files needed to
6812 instantiate @var{os}.
6815 This procedure is provided by the @code{(gnu system)} module. Along
6816 with @code{(gnu services)} (@pxref{Services}), this module contains the
6817 guts of GuixSD. Make sure to visit it!
6820 @node operating-system Reference
6821 @subsection @code{operating-system} Reference
6823 This section summarizes all the options available in
6824 @code{operating-system} declarations (@pxref{Using the Configuration
6827 @deftp {Data Type} operating-system
6828 This is the data type representing an operating system configuration.
6829 By that, we mean all the global system configuration, not per-user
6830 configuration (@pxref{Using the Configuration System}).
6833 @item @code{kernel} (default: @var{linux-libre})
6834 The package object of the operating system kernel to use@footnote{Currently
6835 only the Linux-libre kernel is supported. In the future, it will be
6836 possible to use the GNU@tie{}Hurd.}.
6838 @item @code{kernel-arguments} (default: @code{'()})
6839 List of strings or gexps representing additional arguments to pass on
6840 the command-line of the kernel---e.g., @code{("console=ttyS0")}.
6842 @item @code{bootloader}
6843 The system bootloader configuration object. @xref{GRUB Configuration}.
6845 @item @code{initrd} (default: @code{base-initrd})
6846 A two-argument monadic procedure that returns an initial RAM disk for
6847 the Linux kernel. @xref{Initial RAM Disk}.
6849 @item @code{firmware} (default: @var{%base-firmware})
6851 List of firmware packages loadable by the operating system kernel.
6853 The default includes firmware needed for Atheros-based WiFi devices
6854 (Linux-libre module @code{ath9k}). @xref{Hardware Considerations}, for
6855 more info on supported hardware.
6857 @item @code{host-name}
6860 @item @code{hosts-file}
6862 A file-like object (@pxref{G-Expressions, file-like objects}) for use as
6863 @file{/etc/hosts} (@pxref{Host Names,,, libc, The GNU C Library
6864 Reference Manual}). The default is a file with entries for
6865 @code{localhost} and @var{host-name}.
6867 @item @code{mapped-devices} (default: @code{'()})
6868 A list of mapped devices. @xref{Mapped Devices}.
6870 @item @code{file-systems}
6871 A list of file systems. @xref{File Systems}.
6873 @item @code{swap-devices} (default: @code{'()})
6874 @cindex swap devices
6875 A list of strings identifying devices to be used for ``swap space''
6876 (@pxref{Memory Concepts,,, libc, The GNU C Library Reference Manual}).
6877 For example, @code{'("/dev/sda3")}.
6879 @item @code{users} (default: @code{%base-user-accounts})
6880 @itemx @code{groups} (default: @var{%base-groups})
6881 List of user accounts and groups. @xref{User Accounts}.
6883 @item @code{skeletons} (default: @code{(default-skeletons)})
6884 A list target file name/file-like object tuples (@pxref{G-Expressions,
6885 file-like objects}). These are the skeleton files that will be added to
6886 the home directory of newly-created user accounts.
6888 For instance, a valid value may look like this:
6891 `((".bashrc" ,(plain-file "bashrc" "echo Hello\n"))
6892 (".guile" ,(plain-file "guile"
6893 "(use-modules (ice-9 readline))
6894 (activate-readline)")))
6897 @item @code{issue} (default: @var{%default-issue})
6898 A string denoting the contents of the @file{/etc/issue} file, which is
6899 displayed when users log in on a text console.
6901 @item @code{packages} (default: @var{%base-packages})
6902 The set of packages installed in the global profile, which is accessible
6903 at @file{/run/current-system/profile}.
6905 The default set includes core utilities and it is good practice to
6906 install non-core utilities in user profiles (@pxref{Invoking guix
6909 @item @code{timezone}
6910 A timezone identifying string---e.g., @code{"Europe/Paris"}.
6912 You can run the @command{tzselect} command to find out which timezone
6913 string corresponds to your region. Choosing an invalid timezone name
6914 causes @command{guix system} to fail.
6916 @item @code{locale} (default: @code{"en_US.utf8"})
6917 The name of the default locale (@pxref{Locale Names,,, libc, The GNU C
6918 Library Reference Manual}). @xref{Locales}, for more information.
6920 @item @code{locale-definitions} (default: @var{%default-locale-definitions})
6921 The list of locale definitions to be compiled and that may be used at
6922 run time. @xref{Locales}.
6924 @item @code{locale-libcs} (default: @code{(list @var{glibc})})
6925 The list of GNU@tie{}libc packages whose locale data and tools are used
6926 to build the locale definitions. @xref{Locales}, for compatibility
6927 considerations that justify this option.
6929 @item @code{name-service-switch} (default: @var{%default-nss})
6930 Configuration of the libc name service switch (NSS)---a
6931 @code{<name-service-switch>} object. @xref{Name Service Switch}, for
6934 @item @code{services} (default: @var{%base-services})
6935 A list of service objects denoting system services. @xref{Services}.
6937 @item @code{pam-services} (default: @code{(base-pam-services)})
6939 @cindex pluggable authentication modules
6940 Linux @dfn{pluggable authentication module} (PAM) services.
6941 @c FIXME: Add xref to PAM services section.
6943 @item @code{setuid-programs} (default: @var{%setuid-programs})
6944 List of string-valued G-expressions denoting setuid programs.
6945 @xref{Setuid Programs}.
6947 @item @code{sudoers-file} (default: @var{%sudoers-specification})
6948 @cindex sudoers file
6949 The contents of the @file{/etc/sudoers} file as a file-like object
6950 (@pxref{G-Expressions, @code{local-file} and @code{plain-file}}).
6952 This file specifies which users can use the @command{sudo} command, what
6953 they are allowed to do, and what privileges they may gain. The default
6954 is that only @code{root} and members of the @code{wheel} group may use
6961 @subsection File Systems
6963 The list of file systems to be mounted is specified in the
6964 @code{file-systems} field of the operating system declaration
6965 (@pxref{Using the Configuration System}). Each file system is declared
6966 using the @code{file-system} form, like this:
6970 (mount-point "/home")
6971 (device "/dev/sda3")
6975 As usual, some of the fields are mandatory---those shown in the example
6976 above---while others can be omitted. These are described below.
6978 @deftp {Data Type} file-system
6979 Objects of this type represent file systems to be mounted. They
6980 contain the following members:
6984 This is a string specifying the type of the file system---e.g.,
6987 @item @code{mount-point}
6988 This designates the place where the file system is to be mounted.
6991 This names the ``source'' of the file system. By default it is the name
6992 of a node under @file{/dev}, but its meaning depends on the @code{title}
6993 field described below.
6995 @item @code{title} (default: @code{'device})
6996 This is a symbol that specifies how the @code{device} field is to be
6999 When it is the symbol @code{device}, then the @code{device} field is
7000 interpreted as a file name; when it is @code{label}, then @code{device}
7001 is interpreted as a partition label name; when it is @code{uuid},
7002 @code{device} is interpreted as a partition unique identifier (UUID).
7004 UUIDs may be converted from their string representation (as shown by the
7005 @command{tune2fs -l} command) using the @code{uuid} form@footnote{The
7006 @code{uuid} form expects 16-byte UUIDs as defined in
7007 @uref{https://tools.ietf.org/html/rfc4122, RFC@tie{}4122}. This is the
7008 form of UUID used by the ext2 family of file systems and others, but it
7009 is different from ``UUIDs'' found in FAT file systems, for instance.},
7014 (mount-point "/home")
7017 (device (uuid "4dab5feb-d176-45de-b287-9b0a6e4c01cb")))
7020 The @code{label} and @code{uuid} options offer a way to refer to disk
7021 partitions without having to hard-code their actual device
7022 name@footnote{Note that, while it is tempting to use
7023 @file{/dev/disk/by-uuid} and similar device names to achieve the same
7024 result, this is not recommended: These special device nodes are created
7025 by the udev daemon and may be unavailable at the time the device is
7028 However, when the source of a file system is a mapped device (@pxref{Mapped
7029 Devices}), its @code{device} field @emph{must} refer to the mapped
7030 device name---e.g., @file{/dev/mapper/root-partition}---and consequently
7031 @code{title} must be set to @code{'device}. This is required so that
7032 the system knows that mounting the file system depends on having the
7033 corresponding device mapping established.
7035 @item @code{flags} (default: @code{'()})
7036 This is a list of symbols denoting mount flags. Recognized flags
7037 include @code{read-only}, @code{bind-mount}, @code{no-dev} (disallow
7038 access to special files), @code{no-suid} (ignore setuid and setgid
7039 bits), and @code{no-exec} (disallow program execution.)
7041 @item @code{options} (default: @code{#f})
7042 This is either @code{#f}, or a string denoting mount options.
7044 @item @code{mount?} (default: @code{#t})
7045 This value indicates whether to automatically mount the file system when
7046 the system is brought up. When set to @code{#f}, the file system gets
7047 an entry in @file{/etc/fstab} (read by the @command{mount} command) but
7048 is not automatically mounted.
7050 @item @code{needed-for-boot?} (default: @code{#f})
7051 This Boolean value indicates whether the file system is needed when
7052 booting. If that is true, then the file system is mounted when the
7053 initial RAM disk (initrd) is loaded. This is always the case, for
7054 instance, for the root file system.
7056 @item @code{check?} (default: @code{#t})
7057 This Boolean indicates whether the file system needs to be checked for
7058 errors before being mounted.
7060 @item @code{create-mount-point?} (default: @code{#f})
7061 When true, the mount point is created if it does not exist yet.
7063 @item @code{dependencies} (default: @code{'()})
7064 This is a list of @code{<file-system>} objects representing file systems
7065 that must be mounted before (and unmounted after) this one.
7067 As an example, consider a hierarchy of mounts: @file{/sys/fs/cgroup} is
7068 a dependency of @file{/sys/fs/cgroup/cpu} and
7069 @file{/sys/fs/cgroup/memory}.
7074 The @code{(gnu system file-systems)} exports the following useful
7077 @defvr {Scheme Variable} %base-file-systems
7078 These are essential file systems that are required on normal systems,
7079 such as @var{%pseudo-terminal-file-system} and @var{%immutable-store} (see
7080 below.) Operating system declarations should always contain at least
7084 @defvr {Scheme Variable} %pseudo-terminal-file-system
7085 This is the file system to be mounted as @file{/dev/pts}. It supports
7086 @dfn{pseudo-terminals} created @i{via} @code{openpty} and similar
7087 functions (@pxref{Pseudo-Terminals,,, libc, The GNU C Library Reference
7088 Manual}). Pseudo-terminals are used by terminal emulators such as
7092 @defvr {Scheme Variable} %shared-memory-file-system
7093 This file system is mounted as @file{/dev/shm} and is used to support
7094 memory sharing across processes (@pxref{Memory-mapped I/O,
7095 @code{shm_open},, libc, The GNU C Library Reference Manual}).
7098 @defvr {Scheme Variable} %immutable-store
7099 This file system performs a read-only ``bind mount'' of
7100 @file{/gnu/store}, making it read-only for all the users including
7101 @code{root}. This prevents against accidental modification by software
7102 running as @code{root} or by system administrators.
7104 The daemon itself is still able to write to the store: it remounts it
7105 read-write in its own ``name space.''
7108 @defvr {Scheme Variable} %binary-format-file-system
7109 The @code{binfmt_misc} file system, which allows handling of arbitrary
7110 executable file types to be delegated to user space. This requires the
7111 @code{binfmt.ko} kernel module to be loaded.
7114 @defvr {Scheme Variable} %fuse-control-file-system
7115 The @code{fusectl} file system, which allows unprivileged users to mount
7116 and unmount user-space FUSE file systems. This requires the
7117 @code{fuse.ko} kernel module to be loaded.
7120 @node Mapped Devices
7121 @subsection Mapped Devices
7123 @cindex device mapping
7124 @cindex mapped devices
7125 The Linux kernel has a notion of @dfn{device mapping}: a block device,
7126 such as a hard disk partition, can be @dfn{mapped} into another device,
7127 usually in @code{/dev/mapper/},
7128 with additional processing over the data that flows through
7129 it@footnote{Note that the GNU@tie{}Hurd makes no difference between the
7130 concept of a ``mapped device'' and that of a file system: both boil down
7131 to @emph{translating} input/output operations made on a file to
7132 operations on its backing store. Thus, the Hurd implements mapped
7133 devices, like file systems, using the generic @dfn{translator} mechanism
7134 (@pxref{Translators,,, hurd, The GNU Hurd Reference Manual}).}. A
7135 typical example is encryption device mapping: all writes to the mapped
7136 device are encrypted, and all reads are deciphered, transparently.
7137 Guix extends this notion by considering any device or set of devices that
7138 are @dfn{transformed} in some way to create a new device; for instance,
7139 RAID devices are obtained by @dfn{assembling} several other devices, such
7140 as hard disks or partitions, into a new one that behaves as one partition.
7141 Other examples, not yet implemented, are LVM logical volumes.
7143 Mapped devices are declared using the @code{mapped-device} form,
7144 defined as follows; for examples, see below.
7146 @deftp {Data Type} mapped-device
7147 Objects of this type represent device mappings that will be made when
7148 the system boots up.
7152 This is either a string specifying the name of the block device to be mapped,
7153 such as @code{"/dev/sda3"}, or a list of such strings when several devices
7154 need to be assembled for creating a new one.
7157 This string specifies the name of the resulting mapped device. For
7158 kernel mappers such as encrypted devices of type @code{luks-device-mapping},
7159 specifying @code{"my-partition"} leads to the creation of
7160 the @code{"/dev/mapper/my-partition"} device.
7161 For RAID devices of type @code{raid-device-mapping}, the full device name
7162 such as @code{"/dev/md0"} needs to be given.
7165 This must be a @code{mapped-device-kind} object, which specifies how
7166 @var{source} is mapped to @var{target}.
7170 @defvr {Scheme Variable} luks-device-mapping
7171 This defines LUKS block device encryption using the @command{cryptsetup}
7172 command from the package with the same name. It relies on the
7173 @code{dm-crypt} Linux kernel module.
7176 @defvr {Scheme Variable} raid-device-mapping
7177 This defines a RAID device, which is assembled using the @code{mdadm}
7178 command from the package with the same name. It requires a Linux kernel
7179 module for the appropriate RAID level to be loaded, such as @code{raid456}
7180 for RAID-4, RAID-5 or RAID-6, or @code{raid10} for RAID-10.
7183 @cindex disk encryption
7185 The following example specifies a mapping from @file{/dev/sda3} to
7186 @file{/dev/mapper/home} using LUKS---the
7187 @url{http://code.google.com/p/cryptsetup,Linux Unified Key Setup}, a
7188 standard mechanism for disk encryption.
7189 The @file{/dev/mapper/home}
7190 device can then be used as the @code{device} of a @code{file-system}
7191 declaration (@pxref{File Systems}).
7195 (source "/dev/sda3")
7197 (type luks-device-mapping))
7200 Alternatively, to become independent of device numbering, one may obtain
7201 the LUKS UUID (@dfn{unique identifier}) of the source device by a
7205 cryptsetup luksUUID /dev/sda3
7208 and use it as follows:
7212 (source (uuid "cb67fc72-0d54-4c88-9d4b-b225f30b0f44"))
7214 (type luks-device-mapping))
7217 A RAID device formed of the partitions @file{/dev/sda1} and @file{/dev/sdb1}
7218 may be declared as follows:
7222 (source (list "/dev/sda1" "/dev/sdb1"))
7224 (type raid-device-mapping))
7227 The @file{/dev/md0} device can then be used as the @code{device} of a
7228 @code{file-system} declaration (@pxref{File Systems}).
7229 Note that the RAID level need not be given; it is chosen during the
7230 initial creation and formatting of the RAID device and is determined
7231 automatically later.
7235 @subsection User Accounts
7237 User accounts and groups are entirely managed through the
7238 @code{operating-system} declaration. They are specified with the
7239 @code{user-account} and @code{user-group} forms:
7245 (supplementary-groups '("wheel" ;allow use of sudo, etc.
7247 "video" ;video devices such as webcams
7248 "cdrom")) ;the good ol' CD-ROM
7249 (comment "Bob's sister")
7250 (home-directory "/home/alice"))
7253 When booting or upon completion of @command{guix system reconfigure},
7254 the system ensures that only the user accounts and groups specified in
7255 the @code{operating-system} declaration exist, and with the specified
7256 properties. Thus, account or group creations or modifications made by
7257 directly invoking commands such as @command{useradd} are lost upon
7258 reconfiguration or reboot. This ensures that the system remains exactly
7261 @deftp {Data Type} user-account
7262 Objects of this type represent user accounts. The following members may
7267 The name of the user account.
7270 This is the name (a string) or identifier (a number) of the user group
7271 this account belongs to.
7273 @item @code{supplementary-groups} (default: @code{'()})
7274 Optionally, this can be defined as a list of group names that this
7277 @item @code{uid} (default: @code{#f})
7278 This is the user ID for this account (a number), or @code{#f}. In the
7279 latter case, a number is automatically chosen by the system when the
7282 @item @code{comment} (default: @code{""})
7283 A comment about the account, such as the account owner's full name.
7285 @item @code{home-directory}
7286 This is the name of the home directory for the account.
7288 @item @code{create-home-directory?} (default: @code{#t})
7289 Indicates whether the home directory of this account should be created
7290 if it does not exist yet.
7292 @item @code{shell} (default: Bash)
7293 This is a G-expression denoting the file name of a program to be used as
7294 the shell (@pxref{G-Expressions}).
7296 @item @code{system?} (default: @code{#f})
7297 This Boolean value indicates whether the account is a ``system''
7298 account. System accounts are sometimes treated specially; for instance,
7299 graphical login managers do not list them.
7301 @anchor{user-account-password}
7302 @item @code{password} (default: @code{#f})
7303 You would normally leave this field to @code{#f}, initialize user
7304 passwords as @code{root} with the @command{passwd} command, and then let
7305 users change it with @command{passwd}. Passwords set with
7306 @command{passwd} are of course preserved across reboot and
7309 If you @emph{do} want to have a preset password for an account, then
7310 this field must contain the encrypted password, as a string.
7311 @xref{crypt,,, libc, The GNU C Library Reference Manual}, for more information
7312 on password encryption, and @ref{Encryption,,, guile, GNU Guile Reference
7313 Manual}, for information on Guile's @code{crypt} procedure.
7318 User group declarations are even simpler:
7321 (user-group (name "students"))
7324 @deftp {Data Type} user-group
7325 This type is for, well, user groups. There are just a few fields:
7329 The name of the group.
7331 @item @code{id} (default: @code{#f})
7332 The group identifier (a number). If @code{#f}, a new number is
7333 automatically allocated when the group is created.
7335 @item @code{system?} (default: @code{#f})
7336 This Boolean value indicates whether the group is a ``system'' group.
7337 System groups have low numerical IDs.
7339 @item @code{password} (default: @code{#f})
7340 What, user groups can have a password? Well, apparently yes. Unless
7341 @code{#f}, this field specifies the password of the group.
7346 For convenience, a variable lists all the basic user groups one may
7349 @defvr {Scheme Variable} %base-groups
7350 This is the list of basic user groups that users and/or packages expect
7351 to be present on the system. This includes groups such as ``root'',
7352 ``wheel'', and ``users'', as well as groups used to control access to
7353 specific devices such as ``audio'', ``disk'', and ``cdrom''.
7356 @defvr {Scheme Variable} %base-user-accounts
7357 This is the list of basic system accounts that programs may expect to
7358 find on a GNU/Linux system, such as the ``nobody'' account.
7360 Note that the ``root'' account is not included here. It is a
7361 special-case and is automatically added whether or not it is specified.
7368 A @dfn{locale} defines cultural conventions for a particular language
7369 and region of the world (@pxref{Locales,,, libc, The GNU C Library
7370 Reference Manual}). Each locale has a name that typically has the form
7371 @code{@var{language}_@var{territory}.@var{codeset}}---e.g.,
7372 @code{fr_LU.utf8} designates the locale for the French language, with
7373 cultural conventions from Luxembourg, and using the UTF-8 encoding.
7375 @cindex locale definition
7376 Usually, you will want to specify the default locale for the machine
7377 using the @code{locale} field of the @code{operating-system} declaration
7378 (@pxref{operating-system Reference, @code{locale}}).
7380 The selected locale is automatically added to the @dfn{locale
7381 definitions} known to the system if needed, with its codeset inferred
7382 from its name---e.g., @code{bo_CN.utf8} will be assumed to use the
7383 @code{UTF-8} codeset. Additional locale definitions can be specified in
7384 the @code{locale-definitions} slot of @code{operating-system}---this is
7385 useful, for instance, if the codeset could not be inferred from the
7386 locale name. The default set of locale definitions includes some widely
7387 used locales, but not all the available locales, in order to save space.
7389 For instance, to add the North Frisian locale for Germany, the value of
7393 (cons (locale-definition
7394 (name "fy_DE.utf8") (source "fy_DE"))
7395 %default-locale-definitions)
7398 Likewise, to save space, one might want @code{locale-definitions} to
7399 list only the locales that are actually used, as in:
7402 (list (locale-definition
7403 (name "ja_JP.eucjp") (source "ja_JP")
7404 (charset "EUC-JP")))
7408 The compiled locale definitions are available at
7409 @file{/run/current-system/locale/X.Y}, where @code{X.Y} is the libc
7410 version, which is the default location where the GNU@tie{}libc provided
7411 by Guix looks for locale data. This can be overridden using the
7412 @code{LOCPATH} environment variable (@pxref{locales-and-locpath,
7413 @code{LOCPATH} and locale packages}).
7415 The @code{locale-definition} form is provided by the @code{(gnu system
7416 locale)} module. Details are given below.
7418 @deftp {Data Type} locale-definition
7419 This is the data type of a locale definition.
7424 The name of the locale. @xref{Locale Names,,, libc, The GNU C Library
7425 Reference Manual}, for more information on locale names.
7428 The name of the source for that locale. This is typically the
7429 @code{@var{language}_@var{territory}} part of the locale name.
7431 @item @code{charset} (default: @code{"UTF-8"})
7432 The ``character set'' or ``code set'' for that locale,
7433 @uref{http://www.iana.org/assignments/character-sets, as defined by
7439 @defvr {Scheme Variable} %default-locale-definitions
7440 A list of commonly used UTF-8 locales, used as the default
7441 value of the @code{locale-definitions} field of @code{operating-system}
7445 @cindex normalized codeset in locale names
7446 These locale definitions use the @dfn{normalized codeset} for the part
7447 that follows the dot in the name (@pxref{Using gettextized software,
7448 normalized codeset,, libc, The GNU C Library Reference Manual}). So for
7449 instance it has @code{uk_UA.utf8} but @emph{not}, say,
7453 @subsubsection Locale Data Compatibility Considerations
7455 @cindex incompatibility, of locale data
7456 @code{operating-system} declarations provide a @code{locale-libcs} field
7457 to specify the GNU@tie{}libc packages that are used to compile locale
7458 declarations (@pxref{operating-system Reference}). ``Why would I
7459 care?'', you may ask. Well, it turns out that the binary format of
7460 locale data is occasionally incompatible from one libc version to
7463 @c See <https://sourceware.org/ml/libc-alpha/2015-09/msg00575.html>
7464 @c and <https://lists.gnu.org/archive/html/guix-devel/2015-08/msg00737.html>.
7465 For instance, a program linked against libc version 2.21 is unable to
7466 read locale data produced with libc 2.22; worse, that program
7467 @emph{aborts} instead of simply ignoring the incompatible locale
7468 data@footnote{Versions 2.23 and later of GNU@tie{}libc will simply skip
7469 the incompatible locale data, which is already an improvement.}.
7470 Similarly, a program linked against libc 2.22 can read most, but not
7471 all, of the locale data from libc 2.21 (specifically, @code{LC_COLLATE}
7472 data is incompatible); thus calls to @code{setlocale} may fail, but
7473 programs will not abort.
7475 The ``problem'' in GuixSD is that users have a lot of freedom: They can
7476 choose whether and when to upgrade software in their profiles, and might
7477 be using a libc version different from the one the system administrator
7478 used to build the system-wide locale data.
7480 Fortunately, unprivileged users can also install their own locale data
7481 and define @var{GUIX_LOCPATH} accordingly (@pxref{locales-and-locpath,
7482 @code{GUIX_LOCPATH} and locale packages}).
7484 Still, it is best if the system-wide locale data at
7485 @file{/run/current-system/locale} is built for all the libc versions
7486 actually in use on the system, so that all the programs can access
7487 it---this is especially crucial on a multi-user system. To do that, the
7488 administrator can specify several libc packages in the
7489 @code{locale-libcs} field of @code{operating-system}:
7492 (use-package-modules base)
7496 (locale-libcs (list glibc-2.21 (canonical-package glibc))))
7499 This example would lead to a system containing locale definitions for
7500 both libc 2.21 and the current version of libc in
7501 @file{/run/current-system/locale}.
7505 @subsection Services
7507 @cindex system services
7508 An important part of preparing an @code{operating-system} declaration is
7509 listing @dfn{system services} and their configuration (@pxref{Using the
7510 Configuration System}). System services are typically daemons launched
7511 when the system boots, or other actions needed at that time---e.g.,
7512 configuring network access.
7514 GuixSD has a broad definition of ``service'' (@pxref{Service
7515 Composition}), but many services are managed by the GNU@tie{}Shepherd
7516 (@pxref{Shepherd Services}). On a running system, the @command{herd}
7517 command allows you to list the available services, show their status,
7518 start and stop them, or do other specific operations (@pxref{Jump
7519 Start,,, shepherd, The GNU Shepherd Manual}). For example:
7525 The above command, run as @code{root}, lists the currently defined
7526 services. The @command{herd doc} command shows a synopsis of the given
7531 Run libc's name service cache daemon (nscd).
7534 The @command{start}, @command{stop}, and @command{restart} sub-commands
7535 have the effect you would expect. For instance, the commands below stop
7536 the nscd service and restart the Xorg display server:
7540 Service nscd has been stopped.
7541 # herd restart xorg-server
7542 Service xorg-server has been stopped.
7543 Service xorg-server has been started.
7546 The following sections document the available services, starting with
7547 the core services, that may be used in an @code{operating-system}
7551 * Base Services:: Essential system services.
7552 * Scheduled Job Execution:: The mcron service.
7553 * Networking Services:: Network setup, SSH daemon, etc.
7554 * X Window:: Graphical display.
7555 * Desktop Services:: D-Bus and desktop services.
7556 * Database Services:: SQL databases.
7557 * Mail Services:: IMAP, POP3, SMTP, and all that.
7558 * Web Services:: Web servers.
7559 * Various Services:: Other services.
7563 @subsubsection Base Services
7565 The @code{(gnu services base)} module provides definitions for the basic
7566 services that one expects from the system. The services exported by
7567 this module are listed below.
7569 @defvr {Scheme Variable} %base-services
7570 This variable contains a list of basic services (@pxref{Service Types
7571 and Services}, for more information on service objects) one would
7572 expect from the system: a login service (mingetty) on each tty, syslogd,
7573 the libc name service cache daemon (nscd), the udev device manager, and
7576 This is the default value of the @code{services} field of
7577 @code{operating-system} declarations. Usually, when customizing a
7578 system, you will want to append services to @var{%base-services}, like
7582 (cons* (avahi-service) (lsh-service) %base-services)
7586 @deffn {Scheme Procedure} host-name-service @var{name}
7587 Return a service that sets the host name to @var{name}.
7590 @deffn {Scheme Procedure} mingetty-service @var{config}
7591 Return a service to run mingetty according to @var{config}, a
7592 @code{<mingetty-configuration>} object, which specifies the tty to run, among
7596 @deftp {Data Type} mingetty-configuration
7597 This is the data type representing the configuration of Mingetty, which
7598 implements console log-in.
7603 The name of the console this Mingetty runs on---e.g., @code{"tty1"}.
7606 A file-like object containing the ``message of the day''.
7608 @item @code{auto-login} (default: @code{#f})
7609 When true, this field must be a string denoting the user name under
7610 which the system automatically logs in. When it is @code{#f}, a
7611 user name and password must be entered to log in.
7613 @item @code{login-program} (default: @code{#f})
7614 This must be either @code{#f}, in which case the default log-in program
7615 is used (@command{login} from the Shadow tool suite), or a gexp denoting
7616 the name of the log-in program.
7618 @item @code{login-pause?} (default: @code{#f})
7619 When set to @code{#t} in conjunction with @var{auto-login}, the user
7620 will have to press a key before the log-in shell is launched.
7622 @item @code{mingetty} (default: @var{mingetty})
7623 The Mingetty package to use.
7628 @cindex name service cache daemon
7630 @deffn {Scheme Procedure} nscd-service [@var{config}] [#:glibc glibc] @
7631 [#:name-services '()]
7632 Return a service that runs the libc name service cache daemon (nscd) with the
7633 given @var{config}---an @code{<nscd-configuration>} object. @xref{Name
7634 Service Switch}, for an example.
7637 @defvr {Scheme Variable} %nscd-default-configuration
7638 This is the default @code{<nscd-configuration>} value (see below) used
7639 by @code{nscd-service}. It uses the caches defined by
7640 @var{%nscd-default-caches}; see below.
7643 @deftp {Data Type} nscd-configuration
7644 This is the data type representing the name service cache daemon (nscd)
7649 @item @code{name-services} (default: @code{'()})
7650 List of packages denoting @dfn{name services} that must be visible to
7651 the nscd---e.g., @code{(list @var{nss-mdns})}.
7653 @item @code{glibc} (default: @var{glibc})
7654 Package object denoting the GNU C Library providing the @command{nscd}
7657 @item @code{log-file} (default: @code{"/var/log/nscd.log"})
7658 Name of the nscd log file. This is where debugging output goes when
7659 @code{debug-level} is strictly positive.
7661 @item @code{debug-level} (default: @code{0})
7662 Integer denoting the debugging levels. Higher numbers mean that more
7663 debugging output is logged.
7665 @item @code{caches} (default: @var{%nscd-default-caches})
7666 List of @code{<nscd-cache>} objects denoting things to be cached; see
7672 @deftp {Data Type} nscd-cache
7673 Data type representing a cache database of nscd and its parameters.
7677 @item @code{database}
7678 This is a symbol representing the name of the database to be cached.
7679 Valid values are @code{passwd}, @code{group}, @code{hosts}, and
7680 @code{services}, which designate the corresponding NSS database
7681 (@pxref{NSS Basics,,, libc, The GNU C Library Reference Manual}).
7683 @item @code{positive-time-to-live}
7684 @itemx @code{negative-time-to-live} (default: @code{20})
7685 A number representing the number of seconds during which a positive or
7686 negative lookup result remains in cache.
7688 @item @code{check-files?} (default: @code{#t})
7689 Whether to check for updates of the files corresponding to
7692 For instance, when @var{database} is @code{hosts}, setting this flag
7693 instructs nscd to check for updates in @file{/etc/hosts} and to take
7696 @item @code{persistent?} (default: @code{#t})
7697 Whether the cache should be stored persistently on disk.
7699 @item @code{shared?} (default: @code{#t})
7700 Whether the cache should be shared among users.
7702 @item @code{max-database-size} (default: 32@tie{}MiB)
7703 Maximum size in bytes of the database cache.
7705 @c XXX: 'suggested-size' and 'auto-propagate?' seem to be expert
7706 @c settings, so leave them out.
7711 @defvr {Scheme Variable} %nscd-default-caches
7712 List of @code{<nscd-cache>} objects used by default by
7713 @code{nscd-configuration} (see above).
7715 It enables persistent and aggressive caching of service and host name
7716 lookups. The latter provides better host name lookup performance,
7717 resilience in the face of unreliable name servers, and also better
7718 privacy---often the result of host name lookups is in local cache, so
7719 external name servers do not even need to be queried.
7722 @anchor{syslog-configuration-type}
7723 @deftp {Data Type} syslog-configuration
7724 This data type represents the configuration of the syslog daemon.
7727 @item @code{syslogd} (default: @code{#~(string-append #$inetutils "/libexec/syslogd")})
7728 The syslog daemon to use.
7730 @item @code{config-file} (default: @code{%default-syslog.conf})
7731 The syslog configuration file to use.
7736 @anchor{syslog-service}
7737 @deffn {Scheme Procedure} syslog-service @var{config}
7738 Return a service that runs a syslog daemon according to @var{config}.
7740 @xref{syslogd invocation,,, inetutils, GNU Inetutils}, for more
7741 information on the configuration file syntax.
7744 @anchor{guix-configuration-type}
7745 @deftp {Data Type} guix-configuration
7746 This data type represents the configuration of the Guix build daemon.
7747 @xref{Invoking guix-daemon}, for more information.
7750 @item @code{guix} (default: @var{guix})
7751 The Guix package to use.
7753 @item @code{build-group} (default: @code{"guixbuild"})
7754 Name of the group for build user accounts.
7756 @item @code{build-accounts} (default: @code{10})
7757 Number of build user accounts to create.
7759 @item @code{authorize-key?} (default: @code{#t})
7760 Whether to authorize the substitute keys listed in
7761 @code{authorized-keys}---by default that of @code{hydra.gnu.org}
7762 (@pxref{Substitutes}).
7764 @vindex %default-authorized-guix-keys
7765 @item @code{authorized-keys} (default: @var{%default-authorized-guix-keys})
7766 The list of authorized key files for archive imports, as a list of
7767 string-valued gexps (@pxref{Invoking guix archive}). By default, it
7768 contains that of @code{hydra.gnu.org} (@pxref{Substitutes}).
7770 @item @code{use-substitutes?} (default: @code{#t})
7771 Whether to use substitutes.
7773 @item @code{substitute-urls} (default: @var{%default-substitute-urls})
7774 The list of URLs where to look for substitutes by default.
7776 @item @code{extra-options} (default: @code{'()})
7777 List of extra command-line options for @command{guix-daemon}.
7779 @item @code{lsof} (default: @var{lsof})
7780 @itemx @code{lsh} (default: @var{lsh})
7781 The lsof and lsh packages to use.
7786 @deffn {Scheme Procedure} guix-service @var{config}
7787 Return a service that runs the Guix build daemon according to
7791 @deffn {Scheme Procedure} udev-service [#:udev udev]
7792 Run @var{udev}, which populates the @file{/dev} directory dynamically.
7795 @deffn {Scheme Procedure} urandom-seed-service @var{#f}
7796 Save some entropy in @var{%random-seed-file} to seed @file{/dev/urandom}
7800 @defvr {Scheme Variable} %random-seed-file
7801 This is the name of the file where some random bytes are saved by
7802 @var{urandom-seed-service} to seed @file{/dev/urandom} when rebooting.
7803 It defaults to @file{/var/lib/random-seed}.
7806 @deffn {Scheme Procedure} console-keymap-service @var{files} ...
7807 @cindex keyboard layout
7808 Return a service to load console keymaps from @var{files} using
7809 @command{loadkeys} command. Most likely, you want to load some default
7810 keymap, which can be done like this:
7813 (console-keymap-service "dvorak")
7816 Or, for example, for a Swedish keyboard, you may need to combine
7817 the following keymaps:
7819 (console-keymap-service "se-lat6" "se-fi-lat6")
7822 Also you can specify a full file name (or file names) of your keymap(s).
7823 See @code{man loadkeys} for details.
7827 @deffn {Scheme Procedure} gpm-service [#:gpm @var{gpm}] @
7829 Run @var{gpm}, the general-purpose mouse daemon, with the given
7830 command-line @var{options}. GPM allows users to use the mouse in the console,
7831 notably to select, copy, and paste text. The default value of @var{options}
7832 uses the @code{ps2} protocol, which works for both USB and PS/2 mice.
7834 This service is not part of @var{%base-services}.
7837 @anchor{guix-publish-service}
7838 @deffn {Scheme Procedure} guix-publish-service [#:guix @var{guix}] @
7839 [#:port 80] [#:host "localhost"]
7840 Return a service that runs @command{guix publish} listening on @var{host}
7841 and @var{port} (@pxref{Invoking guix publish}).
7843 This assumes that @file{/etc/guix} already contains a signing key pair as
7844 created by @command{guix archive --generate-key} (@pxref{Invoking guix
7845 archive}). If that is not the case, the service will fail to start.
7848 @anchor{rngd-service}
7849 @deffn {Scheme Procedure} rngd-service [#:rng-tools @var{rng-tools}] @
7850 [#:device "/dev/hwrng"]
7851 Return a service that runs the @command{rngd} program from @var{rng-tools}
7852 to add @var{device} to the kernel's entropy pool. The service will fail if
7853 @var{device} does not exist.
7856 @anchor{pam-limits-service}
7857 @cindex session limits
7860 @deffn {Scheme Procedure} pam-limits-service [#:limits @var{limits}]
7862 Return a service that installs a configuration file for the
7863 @uref{http://linux-pam.org/Linux-PAM-html/sag-pam_limits.html,
7864 @code{pam_limits} module}. The procedure optionally takes a list of
7865 @code{pam-limits-entry} values, which can be used to specify
7866 @code{ulimit} limits and nice priority limits to user sessions.
7868 The following limits definition sets two hard and soft limits for all
7869 login sessions of users in the @code{realtime} group:
7874 (pam-limits-entry "@@realtime" 'both 'rtprio 99)
7875 (pam-limits-entry "@@realtime" 'both 'memlock 'unlimited)))
7878 The first entry increases the maximum realtime priority for
7879 non-privileged processes; the second entry lifts any restriction of the
7880 maximum address space that can be locked in memory. These settings are
7881 commonly used for real-time audio systems.
7884 @node Scheduled Job Execution
7885 @subsubsection Scheduled Job Execution
7888 @cindex scheduling jobs
7889 The @code{(gnu services mcron)} module provides an interface to
7890 GNU@tie{}mcron, a daemon to run jobs at scheduled times (@pxref{Top,,,
7891 mcron, GNU@tie{}mcron}). GNU@tie{}mcron is similar to the traditional
7892 Unix @command{cron} daemon; the main difference is that it is
7893 implemented in Guile Scheme, which provides a lot of flexibility when
7894 specifying the scheduling of jobs and their actions.
7896 The example below defines an operating system that runs the
7897 @command{updatedb} (@pxref{Invoking updatedb,,, find, Finding Files})
7898 and the @command{guix gc} commands (@pxref{Invoking guix gc}) daily, as
7899 well as the @command{mkid} command on behalf of an unprivileged user
7900 (@pxref{mkid invocation,,, idutils, ID Database Utilities}). It uses
7901 gexps to introduce job definitions that are passed to mcron
7902 (@pxref{G-Expressions}).
7905 (use-modules (guix) (gnu) (gnu services mcron))
7906 (use-package-modules base idutils)
7908 (define updatedb-job
7909 ;; Run 'updatedb' at 3AM every day. Here we write the
7910 ;; job's action as a Scheme procedure.
7911 #~(job '(next-hour '(3))
7913 (execl (string-append #$findutils "/bin/updatedb")
7915 "--prunepaths=/tmp /var/tmp /gnu/store"))))
7917 (define garbage-collector-job
7918 ;; Collect garbage 5 minutes after midnight every day.
7919 ;; The job's action is a shell command.
7920 #~(job "5 0 * * *" ;Vixie cron syntax
7924 ;; Update the index database as user "charlie" at 12:15PM
7925 ;; and 19:15PM. This runs from the user's home directory.
7926 #~(job '(next-minute-from (next-hour '(12 19)) '(15))
7927 (string-append #$idutils "/bin/mkid src")
7932 (services (cons (mcron-service (list garbage-collector-job
7938 @xref{Guile Syntax, mcron job specifications,, mcron, GNU@tie{}mcron},
7939 for more information on mcron job specifications. Below is the
7940 reference of the mcron service.
7942 @deffn {Scheme Procedure} mcron-service @var{jobs} [#:mcron @var{mcron2}]
7943 Return an mcron service running @var{mcron} that schedules @var{jobs}, a
7944 list of gexps denoting mcron job specifications.
7946 This is a shorthand for:
7948 (service mcron-service-type
7949 (mcron-configuration (mcron mcron) (jobs jobs)))
7953 @defvr {Scheme Variable} mcron-service-type
7954 This is the type of the @code{mcron} service, whose value is an
7955 @code{mcron-configuration} object.
7957 This service type can be the target of a service extension that provides
7958 it additional job specifications (@pxref{Service Composition}). In
7959 other words, it is possible to define services that provide additional
7963 @deftp {Data Type} mcron-configuration
7964 Data type representing the configuration of mcron.
7967 @item @code{mcron} (default: @var{mcron2})
7968 The mcron package to use.
7971 This is a list of gexps (@pxref{G-Expressions}), where each gexp
7972 corresponds to an mcron job specification (@pxref{Syntax, mcron job
7973 specifications,, mcron, GNU@tie{}mcron}).
7978 @node Networking Services
7979 @subsubsection Networking Services
7981 The @code{(gnu services networking)} module provides services to configure
7982 the network interface.
7984 @cindex DHCP, networking service
7985 @deffn {Scheme Procedure} dhcp-client-service [#:dhcp @var{isc-dhcp}]
7986 Return a service that runs @var{dhcp}, a Dynamic Host Configuration
7987 Protocol (DHCP) client, on all the non-loopback network interfaces.
7990 @deffn {Scheme Procedure} static-networking-service @var{interface} @var{ip} @
7991 [#:gateway #f] [#:name-servers @code{'()}]
7992 Return a service that starts @var{interface} with address @var{ip}. If
7993 @var{gateway} is true, it must be a string specifying the default network
7998 @cindex network management
7999 @deffn {Scheme Procedure} wicd-service [#:wicd @var{wicd}]
8000 Return a service that runs @url{https://launchpad.net/wicd,Wicd}, a network
8001 management daemon that aims to simplify wired and wireless networking.
8003 This service adds the @var{wicd} package to the global profile, providing
8004 several commands to interact with the daemon and configure networking:
8005 @command{wicd-client}, a graphical user interface, and the @command{wicd-cli}
8006 and @command{wicd-curses} user interfaces.
8009 @cindex NetworkManager
8010 @deffn {Scheme Procedure} network-manager-service @
8011 [#:network-manager @var{network-manager}]
8012 Return a service that runs NetworkManager, a network connection manager
8013 attempting to keep network connectivity active when available.
8017 @deffn {Scheme Procedure} connman-service @
8018 [#:connman @var{connman}]
8019 Return a service that runs @url{https://01.org/connman,Connman}, a network
8022 This service adds the @var{connman} package to the global profile, providing
8023 several the @command{connmanctl} command to interact with the daemon and
8024 configure networking."
8027 @deffn {Scheme Procedure} ntp-service [#:ntp @var{ntp}] @
8028 [#:servers @var{%ntp-servers}]
8029 Return a service that runs the daemon from @var{ntp}, the
8030 @uref{http://www.ntp.org, Network Time Protocol package}. The daemon will
8031 keep the system clock synchronized with that of @var{servers}.
8034 @defvr {Scheme Variable} %ntp-servers
8035 List of host names used as the default NTP servers.
8038 @deffn {Scheme Procedure} tor-service [@var{config-file}] [#:tor @var{tor}]
8039 Return a service to run the @uref{https://torproject.org, Tor} anonymous
8042 The daemon runs as the @code{tor} unprivileged user. It is passed
8043 @var{config-file}, a file-like object, with an additional @code{User tor} line
8044 and lines for hidden services added via @code{tor-hidden-service}. Run
8045 @command{man tor} for information about the configuration file.
8048 @cindex hidden service
8049 @deffn {Scheme Procedure} tor-hidden-service @var{name} @var{mapping}
8050 Define a new Tor @dfn{hidden service} called @var{name} and implementing
8051 @var{mapping}. @var{mapping} is a list of port/host tuples, such as:
8054 '((22 "127.0.0.1:22")
8055 (80 "127.0.0.1:8080"))
8058 In this example, port 22 of the hidden service is mapped to local port 22, and
8059 port 80 is mapped to local port 8080.
8061 This creates a @file{/var/lib/tor/hidden-services/@var{name}} directory, where
8062 the @file{hostname} file contains the @code{.onion} host name for the hidden
8065 See @uref{https://www.torproject.org/docs/tor-hidden-service.html.en, the Tor
8066 project's documentation} for more information.
8069 @deffn {Scheme Procedure} bitlbee-service [#:bitlbee bitlbee] @
8070 [#:interface "127.0.0.1"] [#:port 6667] @
8071 [#:extra-settings ""]
8072 Return a service that runs @url{http://bitlbee.org,BitlBee}, a daemon that
8073 acts as a gateway between IRC and chat networks.
8075 The daemon will listen to the interface corresponding to the IP address
8076 specified in @var{interface}, on @var{port}. @code{127.0.0.1} means that only
8077 local clients can connect, whereas @code{0.0.0.0} means that connections can
8078 come from any networking interface.
8080 In addition, @var{extra-settings} specifies a string to append to the
8084 Furthermore, @code{(gnu services ssh)} provides the following services.
8086 @deffn {Scheme Procedure} lsh-service [#:host-key "/etc/lsh/host-key"] @
8087 [#:daemonic? #t] [#:interfaces '()] [#:port-number 22] @
8088 [#:allow-empty-passwords? #f] [#:root-login? #f] @
8089 [#:syslog-output? #t] [#:x11-forwarding? #t] @
8090 [#:tcp/ip-forwarding? #t] [#:password-authentication? #t] @
8091 [#:public-key-authentication? #t] [#:initialize? #t]
8092 Run the @command{lshd} program from @var{lsh} to listen on port @var{port-number}.
8093 @var{host-key} must designate a file containing the host key, and readable
8096 When @var{daemonic?} is true, @command{lshd} will detach from the
8097 controlling terminal and log its output to syslogd, unless one sets
8098 @var{syslog-output?} to false. Obviously, it also makes lsh-service
8099 depend on existence of syslogd service. When @var{pid-file?} is true,
8100 @command{lshd} writes its PID to the file called @var{pid-file}.
8102 When @var{initialize?} is true, automatically create the seed and host key
8103 upon service activation if they do not exist yet. This may take long and
8104 require interaction.
8106 When @var{initialize?} is false, it is up to the user to initialize the
8107 randomness generator (@pxref{lsh-make-seed,,, lsh, LSH Manual}), and to create
8108 a key pair with the private key stored in file @var{host-key} (@pxref{lshd
8109 basics,,, lsh, LSH Manual}).
8111 When @var{interfaces} is empty, lshd listens for connections on all the
8112 network interfaces; otherwise, @var{interfaces} must be a list of host names
8115 @var{allow-empty-passwords?} specifies whether to accept log-ins with empty
8116 passwords, and @var{root-login?} specifies whether to accept log-ins as
8119 The other options should be self-descriptive.
8122 @deffn {Scheme Procedure} dropbear-service [@var{config}]
8123 Run the @uref{https://matt.ucc.asn.au/dropbear/dropbear.html,Dropbear SSH
8124 daemon} with the given @var{config}, a @code{<dropbear-configuration>}
8127 For example, to specify a Dropbear service listening on port 1234, add
8128 this call to the operating system's @code{services} field:
8131 (dropbear-service (dropbear-configuration
8132 (port-number 1234)))
8136 @deftp {Data Type} dropbear-configuration
8137 This data type represents the configuration of a Dropbear SSH daemon.
8140 @item @code{dropbear} (default: @var{dropbear})
8141 The Dropbear package to use.
8143 @item @code{port-number} (default: 22)
8144 The TCP port where the daemon waits for incoming connections.
8146 @item @code{syslog-output?} (default: @code{#t})
8147 Whether to enable syslog output.
8149 @item @code{pid-file} (default: @code{"/var/run/dropbear.pid"})
8150 File name of the daemon's PID file.
8152 @item @code{root-login?} (default: @code{#f})
8153 Whether to allow @code{root} logins.
8155 @item @code{allow-empty-passwords?} (default: @code{#f})
8156 Whether to allow empty passwords.
8158 @item @code{password-authentication?} (default: @code{#t})
8159 Whether to enable password-based authentication.
8163 @defvr {Scheme Variable} %facebook-host-aliases
8164 This variable contains a string for use in @file{/etc/hosts}
8165 (@pxref{Host Names,,, libc, The GNU C Library Reference Manual}). Each
8166 line contains a entry that maps a known server name of the Facebook
8167 on-line service---e.g., @code{www.facebook.com}---to the local
8168 host---@code{127.0.0.1} or its IPv6 equivalent, @code{::1}.
8170 This variable is typically used in the @code{hosts-file} field of an
8171 @code{operating-system} declaration (@pxref{operating-system Reference,
8172 @file{/etc/hosts}}):
8175 (use-modules (gnu) (guix))
8178 (host-name "mymachine")
8181 ;; Create a /etc/hosts file with aliases for "localhost"
8182 ;; and "mymachine", as well as for Facebook servers.
8184 (string-append (local-host-aliases host-name)
8185 %facebook-host-aliases))))
8188 This mechanism can prevent programs running locally, such as Web
8189 browsers, from accessing Facebook.
8192 The @code{(gnu services avahi)} provides the following definition.
8194 @deffn {Scheme Procedure} avahi-service [#:avahi @var{avahi}] @
8195 [#:host-name #f] [#:publish? #t] [#:ipv4? #t] @
8196 [#:ipv6? #t] [#:wide-area? #f] @
8197 [#:domains-to-browse '()] [#:debug? #f]
8198 Return a service that runs @command{avahi-daemon}, a system-wide
8199 mDNS/DNS-SD responder that allows for service discovery and
8200 "zero-configuration" host name lookups (see @uref{http://avahi.org/}), and
8201 extends the name service cache daemon (nscd) so that it can resolve
8202 @code{.local} host names using
8203 @uref{http://0pointer.de/lennart/projects/nss-mdns/, nss-mdns}. Additionally,
8204 add the @var{avahi} package to the system profile so that commands such as
8205 @command{avahi-browse} are directly usable.
8207 If @var{host-name} is different from @code{#f}, use that as the host name to
8208 publish for this machine; otherwise, use the machine's actual host name.
8210 When @var{publish?} is true, publishing of host names and services is allowed;
8211 in particular, avahi-daemon will publish the machine's host name and IP
8212 address via mDNS on the local network.
8214 When @var{wide-area?} is true, DNS-SD over unicast DNS is enabled.
8216 Boolean values @var{ipv4?} and @var{ipv6?} determine whether to use IPv4/IPv6
8222 @subsubsection X Window
8224 Support for the X Window graphical display system---specifically
8225 Xorg---is provided by the @code{(gnu services xorg)} module. Note that
8226 there is no @code{xorg-service} procedure. Instead, the X server is
8227 started by the @dfn{login manager}, currently SLiM.
8229 @deftp {Data Type} sddm-configuration
8230 This is the data type representing the sddm service configuration.
8233 @item @code{display-server} (default: "x11")
8234 Select display server to use for the greeter. Valid values are "x11"
8237 @item @code{numlock} (default: "on")
8238 Valid values are "on", "off" or "none".
8240 @item @code{halt-command} (default @code{#~(string-apppend #$shepherd "/sbin/halt")})
8241 Command to run when halting.
8243 @item @code{reboot-command} (default @code{#~(string-append #$shepherd "/sbin/reboot")})
8244 Command to run when rebooting.
8246 @item @code{theme} (default "maldives")
8247 Theme to use. Default themes provided by SDDM are "elarun" or "maldives".
8249 @item @code{themes-directory} (default "/run/current-system/profile/share/sddm/themes")
8250 Directory to look for themes.
8252 @item @code{faces-directory} (default "/run/current-system/profile/share/sddm/faces")
8253 Directory to look for faces.
8255 @item @code{default-path} (default "/run/current-system/profile/bin")
8256 Default PATH to use.
8258 @item @code{minimum-uid} (default 1000)
8259 Minimum UID to display in SDDM.
8261 @item @code{maximum-uid} (default 2000)
8262 Maximum UID to display in SDDM
8264 @item @code{remember-last-user?} (default #t)
8267 @item @code{remember-last-session?} (default #t)
8268 Remember last session.
8270 @item @code{hide-users} (default "")
8271 Usernames to hide from SDDM greeter.
8273 @item @code{hide-shells} (default @code{#~(string-append #$shadow "/sbin/nologin")})
8274 Users with shells listed will be hidden from the SDDM greeter.
8276 @item @code{session-command} (default @code{#~(string-append #$sddm "/share/sddm/scripts/wayland-session")})
8277 Script to run before starting a wayland session.
8279 @item @code{sessions-directory} (default "/run/current-system/profile/share/wayland-sessions")
8280 Directory to look for desktop files starting wayland sessions.
8282 @item @code{xorg-server-path} (default @code{xorg-start-command})
8283 Path to xorg-server.
8285 @item @code{xauth-path} (default @code{#~(string-append #$xauth "/bin/xauth")})
8288 @item @code{xephyr-path} (default @code{#~(string-append #$xorg-server "/bin/Xephyr")})
8291 @item @code{xdisplay-start} (default @code{#~(string-append #$sddm "/share/sddm/scripts/Xsetup")})
8292 Script to run after starting xorg-server.
8294 @item @code{xdisplay-stop} (default @code{#~(string-append #$sddm "/share/sddm/scripts/Xstop")})
8295 Script to run before stopping xorg-server.
8297 @item @code{xsession-command} (default: @code{xinitr })
8298 Script to run before starting a X session.
8300 @item @code{xsessions-directory} (default: "/run/current-system/profile/share/xsessions")
8301 Directory to look for desktop files starting X sessions.
8303 @item @code{minimum-vt} (default: 7)
8306 @item @code{xserver-arguments} (default "-nolisten tcp")
8307 Arguments to pass to xorg-server.
8309 @item @code{auto-login-user} (default "")
8310 User to use for auto-login.
8312 @item @code{auto-login-session} (default "")
8313 Desktop file to use for auto-login.
8315 @item @code{relogin?} (default #f)
8316 Relogin after logout.
8321 @deffn {Scheme Procedure} sddm-service config
8322 Return a service that spawns the SDDM graphical login manager for config of
8323 type @code{<sddm-configuration>}.
8326 (sddm-service (sddm-configuration
8327 (auto-login-user "Alice")
8328 (auto-login-session "xfce.desktop")))
8332 @deffn {Scheme Procedure} slim-service [#:allow-empty-passwords? #f] @
8333 [#:auto-login? #f] [#:default-user ""] [#:startx] @
8334 [#:theme @var{%default-slim-theme}] @
8335 [#:theme-name @var{%default-slim-theme-name}]
8336 Return a service that spawns the SLiM graphical login manager, which in
8337 turn starts the X display server with @var{startx}, a command as returned by
8338 @code{xorg-start-command}.
8342 SLiM automatically looks for session types described by the @file{.desktop}
8343 files in @file{/run/current-system/profile/share/xsessions} and allows users
8344 to choose a session from the log-in screen using @kbd{F1}. Packages such as
8345 @var{xfce}, @var{sawfish}, and @var{ratpoison} provide @file{.desktop} files;
8346 adding them to the system-wide set of packages automatically makes them
8347 available at the log-in screen.
8349 In addition, @file{~/.xsession} files are honored. When available,
8350 @file{~/.xsession} must be an executable that starts a window manager
8351 and/or other X clients.
8353 When @var{allow-empty-passwords?} is true, allow logins with an empty
8354 password. When @var{auto-login?} is true, log in automatically as
8357 If @var{theme} is @code{#f}, use the default log-in theme; otherwise
8358 @var{theme} must be a gexp denoting the name of a directory containing the
8359 theme to use. In that case, @var{theme-name} specifies the name of the
8363 @defvr {Scheme Variable} %default-theme
8364 @defvrx {Scheme Variable} %default-theme-name
8365 The G-Expression denoting the default SLiM theme and its name.
8368 @deffn {Scheme Procedure} xorg-start-command [#:guile] @
8369 [#:configuration-file #f] [#:xorg-server @var{xorg-server}]
8370 Return a derivation that builds a @var{guile} script to start the X server
8371 from @var{xorg-server}. @var{configuration-file} is the server configuration
8372 file or a derivation that builds it; when omitted, the result of
8373 @code{xorg-configuration-file} is used.
8375 Usually the X server is started by a login manager.
8378 @deffn {Scheme Procedure} xorg-configuration-file @
8379 [#:drivers '()] [#:resolutions '()] [#:extra-config '()]
8380 Return a configuration file for the Xorg server containing search paths for
8381 all the common drivers.
8383 @var{drivers} must be either the empty list, in which case Xorg chooses a
8384 graphics driver automatically, or a list of driver names that will be tried in
8385 this order---e.g., @code{(\"modesetting\" \"vesa\")}.
8387 Likewise, when @var{resolutions} is the empty list, Xorg chooses an
8388 appropriate screen resolution; otherwise, it must be a list of
8389 resolutions---e.g., @code{((1024 768) (640 480))}.
8391 Last, @var{extra-config} is a list of strings or objects appended to the
8392 @code{text-file*} argument list. It is used to pass extra text to be added
8393 verbatim to the configuration file.
8396 @deffn {Scheme Procedure} screen-locker-service @var{package} [@var{name}]
8397 Add @var{package}, a package for a screen-locker or screen-saver whose
8398 command is @var{program}, to the set of setuid programs and add a PAM entry
8399 for it. For example:
8402 (screen-locker-service xlockmore "xlock")
8405 makes the good ol' XlockMore usable.
8409 @node Desktop Services
8410 @subsubsection Desktop Services
8412 The @code{(gnu services desktop)} module provides services that are
8413 usually useful in the context of a ``desktop'' setup---that is, on a
8414 machine running a graphical display server, possibly with graphical user
8415 interfaces, etc. It also defines services that provide specific desktop
8416 environments like GNOME and XFCE.
8418 To simplify things, the module defines a variable containing the set of
8419 services that users typically expect on a machine with a graphical
8420 environment and networking:
8422 @defvr {Scheme Variable} %desktop-services
8423 This is a list of services that builds upon @var{%base-services} and
8424 adds or adjusts services for a typical ``desktop'' setup.
8426 In particular, it adds a graphical login manager (@pxref{X Window,
8427 @code{slim-service}}), screen lockers,
8428 a network management tool (@pxref{Networking
8429 Services, @code{wicd-service}}), energy and color management services,
8430 the @code{elogind} login and seat manager, the Polkit privilege service,
8431 the GeoClue location service, an NTP client (@pxref{Networking
8432 Services}), the Avahi daemon, and has the name service switch service
8433 configured to be able to use @code{nss-mdns} (@pxref{Name Service
8437 The @var{%desktop-services} variable can be used as the @code{services}
8438 field of an @code{operating-system} declaration (@pxref{operating-system
8439 Reference, @code{services}}).
8441 Additionally, the @code{gnome-desktop-service} and
8442 @code{xfce-desktop-service} procedures can add GNOME and/or XFCE to a
8443 system. To ``add GNOME'' means that system-level services like the
8444 backlight adjustment helpers and the power management utilities are
8445 added to the system, extending @code{polkit} and @code{dbus}
8446 appropriately, allowing GNOME to operate with elevated privileges on a
8447 limited number of special-purpose system interfaces. Additionally,
8448 adding a service made by @code{gnome-desktop-service} adds the GNOME
8449 metapackage to the system profile. Likewise, adding the XFCE service
8450 not only adds the @code{xfce} metapackage to the system profile, but it
8451 also gives the Thunar file manager the ability to open a ``root-mode''
8452 file management window, if the user authenticates using the
8453 administrator's password via the standard polkit graphical interface.
8455 @deffn {Scheme Procedure} gnome-desktop-service
8456 Return a service that adds the @code{gnome} package to the system
8457 profile, and extends polkit with the actions from
8458 @code{gnome-settings-daemon}.
8461 @deffn {Scheme Procedure} xfce-desktop-service
8462 Return a service that adds the @code{xfce} package to the system profile,
8463 and extends polkit with the ability for @code{thunar} to manipulate the
8464 file system as root from within a user session, after the user has
8465 authenticated with the administrator's password.
8468 Because the GNOME and XFCE desktop services pull in so many packages,
8469 the default @code{%desktop-services} variable doesn't include either of
8470 them by default. To add GNOME or XFCE, just @code{cons} them onto
8471 @code{%desktop-services} in the @code{services} field of your
8472 @code{operating-system}:
8476 (use-service-modules desktop)
8479 ;; cons* adds items to the list given as its last argument.
8480 (services (cons* (gnome-desktop-service)
8481 (xfce-desktop-service)
8486 These desktop environments will then be available as options in the
8487 graphical login window.
8489 The actual service definitions included in @code{%desktop-services} and
8490 provided by @code{(gnu services dbus)} and @code{(gnu services desktop)}
8491 are described below.
8493 @deffn {Scheme Procedure} dbus-service [#:dbus @var{dbus}] [#:services '()]
8494 Return a service that runs the ``system bus'', using @var{dbus}, with
8495 support for @var{services}.
8497 @uref{http://dbus.freedesktop.org/, D-Bus} is an inter-process communication
8498 facility. Its system bus is used to allow system services to communicate
8499 and to be notified of system-wide events.
8501 @var{services} must be a list of packages that provide an
8502 @file{etc/dbus-1/system.d} directory containing additional D-Bus configuration
8503 and policy files. For example, to allow avahi-daemon to use the system bus,
8504 @var{services} must be equal to @code{(list avahi)}.
8507 @deffn {Scheme Procedure} elogind-service [#:config @var{config}]
8508 Return a service that runs the @code{elogind} login and
8509 seat management daemon. @uref{https://github.com/andywingo/elogind,
8510 Elogind} exposes a D-Bus interface that can be used to know which users
8511 are logged in, know what kind of sessions they have open, suspend the
8512 system, inhibit system suspend, reboot the system, and other tasks.
8514 Elogind handles most system-level power events for a computer, for
8515 example suspending the system when a lid is closed, or shutting it down
8516 when the power button is pressed.
8518 The @var{config} keyword argument specifies the configuration for
8519 elogind, and should be the result of an @code{(elogind-configuration
8520 (@var{parameter} @var{value})...)} invocation. Available parameters and
8521 their default values are:
8524 @item kill-user-processes?
8526 @item kill-only-users
8528 @item kill-exclude-users
8530 @item inhibit-delay-max-seconds
8532 @item handle-power-key
8534 @item handle-suspend-key
8536 @item handle-hibernate-key
8538 @item handle-lid-switch
8540 @item handle-lid-switch-docked
8542 @item power-key-ignore-inhibited?
8544 @item suspend-key-ignore-inhibited?
8546 @item hibernate-key-ignore-inhibited?
8548 @item lid-switch-ignore-inhibited?
8550 @item holdoff-timeout-seconds
8554 @item idle-action-seconds
8556 @item runtime-directory-size-percent
8558 @item runtime-directory-size
8563 @code{("mem" "standby" "freeze")}
8566 @item hibernate-state
8568 @item hibernate-mode
8569 @code{("platform" "shutdown")}
8570 @item hybrid-sleep-state
8572 @item hybrid-sleep-mode
8573 @code{("suspend" "platform" "shutdown")}
8577 @deffn {Scheme Procedure} polkit-service @
8578 [#:polkit @var{polkit}]
8579 Return a service that runs the
8580 @uref{http://www.freedesktop.org/wiki/Software/polkit/, Polkit privilege
8581 management service}, which allows system administrators to grant access to
8582 privileged operations in a structured way. By querying the Polkit service, a
8583 privileged system component can know when it should grant additional
8584 capabilities to ordinary users. For example, an ordinary user can be granted
8585 the capability to suspend the system if the user is logged in locally.
8588 @deffn {Scheme Procedure} upower-service [#:upower @var{upower}] @
8589 [#:watts-up-pro? #f] @
8590 [#:poll-batteries? #t] @
8591 [#:ignore-lid? #f] @
8592 [#:use-percentage-for-policy? #f] @
8593 [#:percentage-low 10] @
8594 [#:percentage-critical 3] @
8595 [#:percentage-action 2] @
8597 [#:time-critical 300] @
8598 [#:time-action 120] @
8599 [#:critical-power-action 'hybrid-sleep]
8600 Return a service that runs @uref{http://upower.freedesktop.org/,
8601 @command{upowerd}}, a system-wide monitor for power consumption and battery
8602 levels, with the given configuration settings. It implements the
8603 @code{org.freedesktop.UPower} D-Bus interface, and is notably used by
8607 @deffn {Scheme Procedure} udisks-service [#:udisks @var{udisks}]
8608 Return a service for @uref{http://udisks.freedesktop.org/docs/latest/,
8609 UDisks}, a @dfn{disk management} daemon that provides user interfaces with
8610 notifications and ways to mount/unmount disks. Programs that talk to UDisks
8611 include the @command{udisksctl} command, part of UDisks, and GNOME Disks.
8614 @deffn {Scheme Procedure} colord-service [#:colord @var{colord}]
8615 Return a service that runs @command{colord}, a system service with a D-Bus
8616 interface to manage the color profiles of input and output devices such as
8617 screens and scanners. It is notably used by the GNOME Color Manager graphical
8618 tool. See @uref{http://www.freedesktop.org/software/colord/, the colord web
8619 site} for more information.
8622 @deffn {Scheme Procedure} geoclue-application name [#:allowed? #t] [#:system? #f] [#:users '()]
8623 Return a configuration allowing an application to access GeoClue
8624 location data. @var{name} is the Desktop ID of the application, without
8625 the @code{.desktop} part. If @var{allowed?} is true, the application
8626 will have access to location information by default. The boolean
8627 @var{system?} value indicates whether an application is a system component
8628 or not. Finally @var{users} is a list of UIDs of all users for which
8629 this application is allowed location info access. An empty users list
8630 means that all users are allowed.
8633 @defvr {Scheme Variable} %standard-geoclue-applications
8634 The standard list of well-known GeoClue application configurations,
8635 granting authority to the GNOME date-and-time utility to ask for the
8636 current location in order to set the time zone, and allowing the
8637 IceCat and Epiphany web browsers to request location information.
8638 IceCat and Epiphany both query the user before allowing a web page to
8639 know the user's location.
8642 @deffn {Scheme Procedure} geoclue-service [#:colord @var{colord}] @
8644 [#:wifi-geolocation-url "https://location.services.mozilla.com/v1/geolocate?key=geoclue"] @
8646 [#:wifi-submission-url "https://location.services.mozilla.com/v1/submit?key=geoclue"] @
8647 [#:submission-nick "geoclue"] @
8648 [#:applications %standard-geoclue-applications]
8649 Return a service that runs the GeoClue location service. This service
8650 provides a D-Bus interface to allow applications to request access to a
8651 user's physical location, and optionally to add information to online
8652 location databases. See
8653 @uref{https://wiki.freedesktop.org/www/Software/GeoClue/, the GeoClue
8654 web site} for more information.
8657 @deffn {Scheme Procedure} bluetooth-service [#:bluez @var{bluez}]
8658 Return a service that runs the @command{bluetoothd} daemon, which manages
8659 all the Bluetooth devices and provides a number of D-Bus interfaces.
8661 Users need to be in the @code{lp} group to access the D-Bus service.
8664 @node Database Services
8665 @subsubsection Database Services
8667 The @code{(gnu services databases)} module provides the following services.
8669 @deffn {Scheme Procedure} postgresql-service [#:postgresql postgresql] @
8670 [#:config-file] [#:data-directory ``/var/lib/postgresql/data'']
8671 Return a service that runs @var{postgresql}, the PostgreSQL database
8674 The PostgreSQL daemon loads its runtime configuration from
8675 @var{config-file} and stores the database cluster in
8676 @var{data-directory}.
8679 @deffn {Scheme Procedure} mysql-service [#:config (mysql-configuration)]
8680 Return a service that runs @command{mysqld}, the MySQL or MariaDB
8683 The optional @var{config} argument specifies the configuration for
8684 @command{mysqld}, which should be a @code{<mysql-configuraiton>} object.
8687 @deftp {Data Type} mysql-configuration
8688 Data type representing the configuration of @var{mysql-service}.
8691 @item @code{mysql} (default: @var{mariadb})
8692 Package object of the MySQL database server, can be either @var{mariadb}
8695 For MySQL, a temporary root password will be displayed at activation time.
8696 For MariaDB, the root password is empty.
8701 @subsubsection Mail Services
8703 The @code{(gnu services mail)} module provides Guix service definitions
8704 for mail services. Currently the only implemented service is Dovecot,
8705 an IMAP, POP3, and LMTP server.
8707 Guix does not yet have a mail transfer agent (MTA), although for some
8708 lightweight purposes the @code{esmtp} relay-only MTA may suffice. Help
8709 is needed to properly integrate a full MTA, such as Postfix. Patches
8712 To add an IMAP/POP3 server to a GuixSD system, add a
8713 @code{dovecot-service} to the operating system definition:
8715 @deffn {Scheme Procedure} dovecot-service [#:config (dovecot-configuration)]
8716 Return a service that runs the Dovecot IMAP/POP3/LMTP mail server.
8719 By default, Dovecot does not need much configuration; the default
8720 configuration object created by @code{(dovecot-configuration)} will
8721 suffice if your mail is delivered to @code{~/Maildir}. A self-signed
8722 certificate will be generated for TLS-protected connections, though
8723 Dovecot will also listen on cleartext ports by default. There are a
8724 number of options, though, which mail administrators might need to change,
8725 and as is the case with other services, Guix allows the system
8726 administrator to specify these parameters via a uniform Scheme interface.
8728 For example, to specify that mail is located at @code{maildir~/.mail},
8729 one would instantiate the Dovecot service like this:
8732 (dovecot-service #:config
8733 (dovecot-configuration
8734 (mail-location "maildir:~/.mail")))
8737 The available configuration parameters follow. Each parameter
8738 definition is preceded by its type; for example, @samp{string-list foo}
8739 indicates that the @code{foo} parameter should be specified as a list of
8740 strings. There is also a way to specify the configuration as a string,
8741 if you have an old @code{dovecot.conf} file that you want to port over
8742 from some other system; see the end for more details.
8744 @c The following documentation was initially generated by
8745 @c (generate-documentation) in (gnu services mail). Manually maintained
8746 @c documentation is better, so we shouldn't hesitate to edit below as
8747 @c needed. However if the change you want to make to this documentation
8748 @c can be done in an automated way, it's probably easier to change
8749 @c (generate-documentation) than to make it below and have to deal with
8750 @c the churn as dovecot updates.
8752 Available @code{dovecot-configuration} fields are:
8754 @deftypevr {@code{dovecot-configuration} parameter} package dovecot
8755 The dovecot package.
8758 @deftypevr {@code{dovecot-configuration} parameter} comma-separated-string-list listen
8759 A list of IPs or hosts where to listen for connections. @samp{*}
8760 listens on all IPv4 interfaces, @samp{::} listens on all IPv6
8761 interfaces. If you want to specify non-default ports or anything more
8762 complex, customize the address and port fields of the
8763 @samp{inet-listener} of the specific services you are interested in.
8766 @deftypevr {@code{dovecot-configuration} parameter} protocol-configuration-list protocols
8767 List of protocols we want to serve. Available protocols include
8768 @samp{imap}, @samp{pop3}, and @samp{lmtp}.
8770 Available @code{protocol-configuration} fields are:
8772 @deftypevr {@code{protocol-configuration} parameter} string name
8773 The name of the protocol.
8776 @deftypevr {@code{protocol-configuration} parameter} string auth-socket-path
8777 UNIX socket path to the master authentication server to find users.
8778 This is used by imap (for shared users) and lda.
8779 It defaults to @samp{"/var/run/dovecot/auth-userdb"}.
8782 @deftypevr {@code{protocol-configuration} parameter} space-separated-string-list mail-plugins
8783 Space separated list of plugins to load.
8786 @deftypevr {@code{protocol-configuration} parameter} non-negative-integer mail-max-userip-connections
8787 Maximum number of IMAP connections allowed for a user from each IP
8788 address. NOTE: The username is compared case-sensitively.
8789 Defaults to @samp{10}.
8794 @deftypevr {@code{dovecot-configuration} parameter} service-configuration-list services
8795 List of services to enable. Available services include @samp{imap},
8796 @samp{imap-login}, @samp{pop3}, @samp{pop3-login}, @samp{auth}, and
8799 Available @code{service-configuration} fields are:
8801 @deftypevr {@code{service-configuration} parameter} string kind
8802 The service kind. Valid values include @code{director},
8803 @code{imap-login}, @code{pop3-login}, @code{lmtp}, @code{imap},
8804 @code{pop3}, @code{auth}, @code{auth-worker}, @code{dict},
8805 @code{tcpwrap}, @code{quota-warning}, or anything else.
8808 @deftypevr {@code{service-configuration} parameter} listener-configuration-list listeners
8809 Listeners for the service. A listener is either a
8810 @code{unix-listener-configuration}, a @code{fifo-listener-configuration}, or
8811 an @code{inet-listener-configuration}.
8812 Defaults to @samp{()}.
8814 Available @code{unix-listener-configuration} fields are:
8816 @deftypevr {@code{unix-listener-configuration} parameter} file-name path
8817 The file name on which to listen.
8820 @deftypevr {@code{unix-listener-configuration} parameter} string mode
8821 The access mode for the socket.
8822 Defaults to @samp{"0600"}.
8825 @deftypevr {@code{unix-listener-configuration} parameter} string user
8826 The user to own the socket.
8827 Defaults to @samp{""}.
8830 @deftypevr {@code{unix-listener-configuration} parameter} string group
8831 The group to own the socket.
8832 Defaults to @samp{""}.
8836 Available @code{fifo-listener-configuration} fields are:
8838 @deftypevr {@code{fifo-listener-configuration} parameter} file-name path
8839 The file name on which to listen.
8842 @deftypevr {@code{fifo-listener-configuration} parameter} string mode
8843 The access mode for the socket.
8844 Defaults to @samp{"0600"}.
8847 @deftypevr {@code{fifo-listener-configuration} parameter} string user
8848 The user to own the socket.
8849 Defaults to @samp{""}.
8852 @deftypevr {@code{fifo-listener-configuration} parameter} string group
8853 The group to own the socket.
8854 Defaults to @samp{""}.
8858 Available @code{inet-listener-configuration} fields are:
8860 @deftypevr {@code{inet-listener-configuration} parameter} string protocol
8861 The protocol to listen for.
8864 @deftypevr {@code{inet-listener-configuration} parameter} string address
8865 The address on which to listen, or empty for all addresses.
8866 Defaults to @samp{""}.
8869 @deftypevr {@code{inet-listener-configuration} parameter} non-negative-integer port
8870 The port on which to listen.
8873 @deftypevr {@code{inet-listener-configuration} parameter} boolean ssl?
8874 Whether to use SSL for this service; @samp{yes}, @samp{no}, or
8876 Defaults to @samp{#t}.
8881 @deftypevr {@code{service-configuration} parameter} non-negative-integer service-count
8882 Number of connections to handle before starting a new process.
8883 Typically the only useful values are 0 (unlimited) or 1. 1 is more
8884 secure, but 0 is faster. <doc/wiki/LoginProcess.txt>.
8885 Defaults to @samp{1}.
8888 @deftypevr {@code{service-configuration} parameter} non-negative-integer process-min-avail
8889 Number of processes to always keep waiting for more connections.
8890 Defaults to @samp{0}.
8893 @deftypevr {@code{service-configuration} parameter} non-negative-integer vsz-limit
8894 If you set @samp{service-count 0}, you probably need to grow
8896 Defaults to @samp{256000000}.
8901 @deftypevr {@code{dovecot-configuration} parameter} dict-configuration dict
8902 Dict configuration, as created by the @code{dict-configuration}
8905 Available @code{dict-configuration} fields are:
8907 @deftypevr {@code{dict-configuration} parameter} free-form-fields entries
8908 A list of key-value pairs that this dict should hold.
8909 Defaults to @samp{()}.
8914 @deftypevr {@code{dovecot-configuration} parameter} passdb-configuration-list passdbs
8915 A list of passdb configurations, each one created by the
8916 @code{passdb-configuration} constructor.
8918 Available @code{passdb-configuration} fields are:
8920 @deftypevr {@code{passdb-configuration} parameter} string driver
8921 The driver that the passdb should use. Valid values include
8922 @samp{pam}, @samp{passwd}, @samp{shadow}, @samp{bsdauth}, and
8924 Defaults to @samp{"pam"}.
8927 @deftypevr {@code{passdb-configuration} parameter} free-form-args args
8928 A list of key-value args to the passdb driver.
8929 Defaults to @samp{()}.
8934 @deftypevr {@code{dovecot-configuration} parameter} userdb-configuration-list userdbs
8935 List of userdb configurations, each one created by the
8936 @code{userdb-configuration} constructor.
8938 Available @code{userdb-configuration} fields are:
8940 @deftypevr {@code{userdb-configuration} parameter} string driver
8941 The driver that the userdb should use. Valid values include
8942 @samp{passwd} and @samp{static}.
8943 Defaults to @samp{"passwd"}.
8946 @deftypevr {@code{userdb-configuration} parameter} free-form-args args
8947 A list of key-value args to the userdb driver.
8948 Defaults to @samp{()}.
8951 @deftypevr {@code{userdb-configuration} parameter} free-form-args override-fields
8952 Override fields from passwd.
8953 Defaults to @samp{()}.
8958 @deftypevr {@code{dovecot-configuration} parameter} plugin-configuration plugin-configuration
8959 Plug-in configuration, created by the @code{plugin-configuration}
8963 @deftypevr {@code{dovecot-configuration} parameter} list-of-namespace-configuration namespaces
8964 List of namespaces. Each item in the list is created by the
8965 @code{namespace-configuration} constructor.
8967 Available @code{namespace-configuration} fields are:
8969 @deftypevr {@code{namespace-configuration} parameter} string name
8970 Name for this namespace.
8973 @deftypevr {@code{namespace-configuration} parameter} string type
8974 Namespace type: @samp{private}, @samp{shared} or @samp{public}.
8975 Defaults to @samp{"private"}.
8978 @deftypevr {@code{namespace-configuration} parameter} string separator
8979 Hierarchy separator to use. You should use the same separator for
8980 all namespaces or some clients get confused. @samp{/} is usually a good
8981 one. The default however depends on the underlying mail storage
8983 Defaults to @samp{""}.
8986 @deftypevr {@code{namespace-configuration} parameter} string prefix
8987 Prefix required to access this namespace. This needs to be
8988 different for all namespaces. For example @samp{Public/}.
8989 Defaults to @samp{""}.
8992 @deftypevr {@code{namespace-configuration} parameter} string location
8993 Physical location of the mailbox. This is in the same format as
8994 mail_location, which is also the default for it.
8995 Defaults to @samp{""}.
8998 @deftypevr {@code{namespace-configuration} parameter} boolean inbox?
8999 There can be only one INBOX, and this setting defines which
9001 Defaults to @samp{#f}.
9004 @deftypevr {@code{namespace-configuration} parameter} boolean hidden?
9005 If namespace is hidden, it's not advertised to clients via NAMESPACE
9006 extension. You'll most likely also want to set @samp{list? #f}. This is mostly
9007 useful when converting from another server with different namespaces
9008 which you want to deprecate but still keep working. For example you can
9009 create hidden namespaces with prefixes @samp{~/mail/}, @samp{~%u/mail/}
9011 Defaults to @samp{#f}.
9014 @deftypevr {@code{namespace-configuration} parameter} boolean list?
9015 Show the mailboxes under this namespace with the LIST command. This
9016 makes the namespace visible for clients that do not support the NAMESPACE
9017 extension. The special @code{children} value lists child mailboxes, but
9018 hides the namespace prefix.
9019 Defaults to @samp{#t}.
9022 @deftypevr {@code{namespace-configuration} parameter} boolean subscriptions?
9023 Namespace handles its own subscriptions. If set to @code{#f}, the
9024 parent namespace handles them. The empty prefix should always have this
9026 Defaults to @samp{#t}.
9029 @deftypevr {@code{namespace-configuration} parameter} mailbox-configuration-list mailboxes
9030 List of predefined mailboxes in this namespace.
9031 Defaults to @samp{()}.
9033 Available @code{mailbox-configuration} fields are:
9035 @deftypevr {@code{mailbox-configuration} parameter} string name
9036 Name for this mailbox.
9039 @deftypevr {@code{mailbox-configuration} parameter} string auto
9040 @samp{create} will automatically create this mailbox.
9041 @samp{subscribe} will both create and subscribe to the mailbox.
9042 Defaults to @samp{"no"}.
9045 @deftypevr {@code{mailbox-configuration} parameter} space-separated-string-list special-use
9046 List of IMAP @code{SPECIAL-USE} attributes as specified by RFC 6154.
9047 Valid values are @code{\All}, @code{\Archive}, @code{\Drafts},
9048 @code{\Flagged}, @code{\Junk}, @code{\Sent}, and @code{\Trash}.
9049 Defaults to @samp{()}.
9056 @deftypevr {@code{dovecot-configuration} parameter} file-name base-dir
9057 Base directory where to store runtime data.
9058 Defaults to @samp{"/var/run/dovecot/"}.
9061 @deftypevr {@code{dovecot-configuration} parameter} string login-greeting
9062 Greeting message for clients.
9063 Defaults to @samp{"Dovecot ready."}.
9066 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-trusted-networks
9067 List of trusted network ranges. Connections from these IPs are
9068 allowed to override their IP addresses and ports (for logging and for
9069 authentication checks). @samp{disable-plaintext-auth} is also ignored
9070 for these networks. Typically you would specify your IMAP proxy servers
9072 Defaults to @samp{()}.
9075 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-access-sockets
9076 List of login access check sockets (e.g. tcpwrap).
9077 Defaults to @samp{()}.
9080 @deftypevr {@code{dovecot-configuration} parameter} boolean verbose-proctitle?
9081 Show more verbose process titles (in ps). Currently shows user name
9082 and IP address. Useful for seeing who is actually using the IMAP
9083 processes (e.g. shared mailboxes or if the same uid is used for multiple
9085 Defaults to @samp{#f}.
9088 @deftypevr {@code{dovecot-configuration} parameter} boolean shutdown-clients?
9089 Should all processes be killed when Dovecot master process shuts down.
9090 Setting this to @code{#f} means that Dovecot can be upgraded without
9091 forcing existing client connections to close (although that could also
9092 be a problem if the upgrade is e.g. due to a security fix).
9093 Defaults to @samp{#t}.
9096 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer doveadm-worker-count
9097 If non-zero, run mail commands via this many connections to doveadm
9098 server, instead of running them directly in the same process.
9099 Defaults to @samp{0}.
9102 @deftypevr {@code{dovecot-configuration} parameter} string doveadm-socket-path
9103 UNIX socket or host:port used for connecting to doveadm server.
9104 Defaults to @samp{"doveadm-server"}.
9107 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list import-environment
9108 List of environment variables that are preserved on Dovecot startup
9109 and passed down to all of its child processes. You can also give
9110 key=value pairs to always set specific settings.
9113 @deftypevr {@code{dovecot-configuration} parameter} boolean disable-plaintext-auth?
9114 Disable LOGIN command and all other plaintext authentications unless
9115 SSL/TLS is used (LOGINDISABLED capability). Note that if the remote IP
9116 matches the local IP (i.e. you're connecting from the same computer),
9117 the connection is considered secure and plaintext authentication is
9118 allowed. See also ssl=required setting.
9119 Defaults to @samp{#t}.
9122 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer auth-cache-size
9123 Authentication cache size (e.g. @samp{#e10e6}). 0 means it's disabled.
9124 Note that bsdauth, PAM and vpopmail require @samp{cache-key} to be set
9125 for caching to be used.
9126 Defaults to @samp{0}.
9129 @deftypevr {@code{dovecot-configuration} parameter} string auth-cache-ttl
9130 Time to live for cached data. After TTL expires the cached record
9131 is no longer used, *except* if the main database lookup returns internal
9132 failure. We also try to handle password changes automatically: If
9133 user's previous authentication was successful, but this one wasn't, the
9134 cache isn't used. For now this works only with plaintext
9136 Defaults to @samp{"1 hour"}.
9139 @deftypevr {@code{dovecot-configuration} parameter} string auth-cache-negative-ttl
9140 TTL for negative hits (user not found, password mismatch).
9141 0 disables caching them completely.
9142 Defaults to @samp{"1 hour"}.
9145 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list auth-realms
9146 List of realms for SASL authentication mechanisms that need them.
9147 You can leave it empty if you don't want to support multiple realms.
9148 Many clients simply use the first one listed here, so keep the default
9150 Defaults to @samp{()}.
9153 @deftypevr {@code{dovecot-configuration} parameter} string auth-default-realm
9154 Default realm/domain to use if none was specified. This is used for
9155 both SASL realms and appending @@domain to username in plaintext
9157 Defaults to @samp{""}.
9160 @deftypevr {@code{dovecot-configuration} parameter} string auth-username-chars
9161 List of allowed characters in username. If the user-given username
9162 contains a character not listed in here, the login automatically fails.
9163 This is just an extra check to make sure user can't exploit any
9164 potential quote escaping vulnerabilities with SQL/LDAP databases. If
9165 you want to allow all characters, set this value to empty.
9166 Defaults to @samp{"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890.-_@@"}.
9169 @deftypevr {@code{dovecot-configuration} parameter} string auth-username-translation
9170 Username character translations before it's looked up from
9171 databases. The value contains series of from -> to characters. For
9172 example @samp{#@@/@@} means that @samp{#} and @samp{/} characters are
9173 translated to @samp{@@}.
9174 Defaults to @samp{""}.
9177 @deftypevr {@code{dovecot-configuration} parameter} string auth-username-format
9178 Username formatting before it's looked up from databases. You can
9179 use the standard variables here, e.g. %Lu would lowercase the username,
9180 %n would drop away the domain if it was given, or @samp{%n-AT-%d} would
9181 change the @samp{@@} into @samp{-AT-}. This translation is done after
9182 @samp{auth-username-translation} changes.
9183 Defaults to @samp{"%Lu"}.
9186 @deftypevr {@code{dovecot-configuration} parameter} string auth-master-user-separator
9187 If you want to allow master users to log in by specifying the master
9188 username within the normal username string (i.e. not using SASL
9189 mechanism's support for it), you can specify the separator character
9190 here. The format is then <username><separator><master username>.
9191 UW-IMAP uses @samp{*} as the separator, so that could be a good
9193 Defaults to @samp{""}.
9196 @deftypevr {@code{dovecot-configuration} parameter} string auth-anonymous-username
9197 Username to use for users logging in with ANONYMOUS SASL
9199 Defaults to @samp{"anonymous"}.
9202 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer auth-worker-max-count
9203 Maximum number of dovecot-auth worker processes. They're used to
9204 execute blocking passdb and userdb queries (e.g. MySQL and PAM).
9205 They're automatically created and destroyed as needed.
9206 Defaults to @samp{30}.
9209 @deftypevr {@code{dovecot-configuration} parameter} string auth-gssapi-hostname
9210 Host name to use in GSSAPI principal names. The default is to use
9211 the name returned by gethostname(). Use @samp{$ALL} (with quotes) to
9212 allow all keytab entries.
9213 Defaults to @samp{""}.
9216 @deftypevr {@code{dovecot-configuration} parameter} string auth-krb5-keytab
9217 Kerberos keytab to use for the GSSAPI mechanism. Will use the
9218 system default (usually /etc/krb5.keytab) if not specified. You may
9219 need to change the auth service to run as root to be able to read this
9221 Defaults to @samp{""}.
9224 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-use-winbind?
9225 Do NTLM and GSS-SPNEGO authentication using Samba's winbind daemon
9226 and @samp{ntlm-auth} helper.
9227 <doc/wiki/Authentication/Mechanisms/Winbind.txt>.
9228 Defaults to @samp{#f}.
9231 @deftypevr {@code{dovecot-configuration} parameter} file-name auth-winbind-helper-path
9232 Path for Samba's @samp{ntlm-auth} helper binary.
9233 Defaults to @samp{"/usr/bin/ntlm_auth"}.
9236 @deftypevr {@code{dovecot-configuration} parameter} string auth-failure-delay
9237 Time to delay before replying to failed authentications.
9238 Defaults to @samp{"2 secs"}.
9241 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-ssl-require-client-cert?
9242 Require a valid SSL client certificate or the authentication
9244 Defaults to @samp{#f}.
9247 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-ssl-username-from-cert?
9248 Take the username from client's SSL certificate, using
9249 @code{X509_NAME_get_text_by_NID()} which returns the subject's DN's
9251 Defaults to @samp{#f}.
9254 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list auth-mechanisms
9255 List of wanted authentication mechanisms. Supported mechanisms are:
9256 @samp{plain}, @samp{login}, @samp{digest-md5}, @samp{cram-md5},
9257 @samp{ntlm}, @samp{rpa}, @samp{apop}, @samp{anonymous}, @samp{gssapi},
9258 @samp{otp}, @samp{skey}, and @samp{gss-spnego}. NOTE: See also
9259 @samp{disable-plaintext-auth} setting.
9262 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list director-servers
9263 List of IPs or hostnames to all director servers, including ourself.
9264 Ports can be specified as ip:port. The default port is the same as what
9265 director service's @samp{inet-listener} is using.
9266 Defaults to @samp{()}.
9269 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list director-mail-servers
9270 List of IPs or hostnames to all backend mail servers. Ranges are
9271 allowed too, like 10.0.0.10-10.0.0.30.
9272 Defaults to @samp{()}.
9275 @deftypevr {@code{dovecot-configuration} parameter} string director-user-expire
9276 How long to redirect users to a specific server after it no longer
9277 has any connections.
9278 Defaults to @samp{"15 min"}.
9281 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer director-doveadm-port
9282 TCP/IP port that accepts doveadm connections (instead of director
9283 connections) If you enable this, you'll also need to add
9284 @samp{inet-listener} for the port.
9285 Defaults to @samp{0}.
9288 @deftypevr {@code{dovecot-configuration} parameter} string director-username-hash
9289 How the username is translated before being hashed. Useful values
9290 include %Ln if user can log in with or without @@domain, %Ld if mailboxes
9291 are shared within domain.
9292 Defaults to @samp{"%Lu"}.
9295 @deftypevr {@code{dovecot-configuration} parameter} string log-path
9296 Log file to use for error messages. @samp{syslog} logs to syslog,
9297 @samp{/dev/stderr} logs to stderr.
9298 Defaults to @samp{"syslog"}.
9301 @deftypevr {@code{dovecot-configuration} parameter} string info-log-path
9302 Log file to use for informational messages. Defaults to
9304 Defaults to @samp{""}.
9307 @deftypevr {@code{dovecot-configuration} parameter} string debug-log-path
9308 Log file to use for debug messages. Defaults to
9309 @samp{info-log-path}.
9310 Defaults to @samp{""}.
9313 @deftypevr {@code{dovecot-configuration} parameter} string syslog-facility
9314 Syslog facility to use if you're logging to syslog. Usually if you
9315 don't want to use @samp{mail}, you'll use local0..local7. Also other
9316 standard facilities are supported.
9317 Defaults to @samp{"mail"}.
9320 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-verbose?
9321 Log unsuccessful authentication attempts and the reasons why they
9323 Defaults to @samp{#f}.
9326 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-verbose-passwords?
9327 In case of password mismatches, log the attempted password. Valid
9328 values are no, plain and sha1. sha1 can be useful for detecting brute
9329 force password attempts vs. user simply trying the same password over
9330 and over again. You can also truncate the value to n chars by appending
9332 Defaults to @samp{#f}.
9335 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-debug?
9336 Even more verbose logging for debugging purposes. Shows for example
9338 Defaults to @samp{#f}.
9341 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-debug-passwords?
9342 In case of password mismatches, log the passwords and used scheme so
9343 the problem can be debugged. Enabling this also enables
9345 Defaults to @samp{#f}.
9348 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-debug?
9349 Enable mail process debugging. This can help you figure out why
9350 Dovecot isn't finding your mails.
9351 Defaults to @samp{#f}.
9354 @deftypevr {@code{dovecot-configuration} parameter} boolean verbose-ssl?
9355 Show protocol level SSL errors.
9356 Defaults to @samp{#f}.
9359 @deftypevr {@code{dovecot-configuration} parameter} string log-timestamp
9360 Prefix for each line written to log file. % codes are in
9362 Defaults to @samp{"\"%b %d %H:%M:%S \""}.
9365 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-log-format-elements
9366 List of elements we want to log. The elements which have a
9367 non-empty variable value are joined together to form a comma-separated
9371 @deftypevr {@code{dovecot-configuration} parameter} string login-log-format
9372 Login log format. %s contains @samp{login-log-format-elements}
9373 string, %$ contains the data we want to log.
9374 Defaults to @samp{"%$: %s"}.
9377 @deftypevr {@code{dovecot-configuration} parameter} string mail-log-prefix
9378 Log prefix for mail processes. See doc/wiki/Variables.txt for list
9379 of possible variables you can use.
9380 Defaults to @samp{"\"%s(%u): \""}.
9383 @deftypevr {@code{dovecot-configuration} parameter} string deliver-log-format
9384 Format to use for logging mail deliveries. You can use variables:
9387 Delivery status message (e.g. @samp{saved to INBOX})
9399 Defaults to @samp{"msgid=%m: %$"}.
9402 @deftypevr {@code{dovecot-configuration} parameter} string mail-location
9403 Location for users' mailboxes. The default is empty, which means
9404 that Dovecot tries to find the mailboxes automatically. This won't work
9405 if the user doesn't yet have any mail, so you should explicitly tell
9406 Dovecot the full location.
9408 If you're using mbox, giving a path to the INBOX
9409 file (e.g. /var/mail/%u) isn't enough. You'll also need to tell Dovecot
9410 where the other mailboxes are kept. This is called the "root mail
9411 directory", and it must be the first path given in the
9412 @samp{mail-location} setting.
9414 There are a few special variables you can use, eg.:
9420 user part in user@@domain, same as %u if there's no domain
9422 domain part in user@@domain, empty if there's no domain
9427 See doc/wiki/Variables.txt for full list. Some examples:
9429 @item maildir:~/Maildir
9430 @item mbox:~/mail:INBOX=/var/mail/%u
9431 @item mbox:/var/mail/%d/%1n/%n:INDEX=/var/indexes/%d/%1n/%
9433 Defaults to @samp{""}.
9436 @deftypevr {@code{dovecot-configuration} parameter} string mail-uid
9437 System user and group used to access mails. If you use multiple,
9438 userdb can override these by returning uid or gid fields. You can use
9439 either numbers or names. <doc/wiki/UserIds.txt>.
9440 Defaults to @samp{""}.
9443 @deftypevr {@code{dovecot-configuration} parameter} string mail-gid
9445 Defaults to @samp{""}.
9448 @deftypevr {@code{dovecot-configuration} parameter} string mail-privileged-group
9449 Group to enable temporarily for privileged operations. Currently
9450 this is used only with INBOX when either its initial creation or
9451 dotlocking fails. Typically this is set to "mail" to give access to
9453 Defaults to @samp{""}.
9456 @deftypevr {@code{dovecot-configuration} parameter} string mail-access-groups
9457 Grant access to these supplementary groups for mail processes.
9458 Typically these are used to set up access to shared mailboxes. Note
9459 that it may be dangerous to set these if users can create
9460 symlinks (e.g. if "mail" group is set here, ln -s /var/mail ~/mail/var
9461 could allow a user to delete others' mailboxes, or ln -s
9462 /secret/shared/box ~/mail/mybox would allow reading it).
9463 Defaults to @samp{""}.
9466 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-full-filesystem-access?
9467 Allow full filesystem access to clients. There's no access checks
9468 other than what the operating system does for the active UID/GID. It
9469 works with both maildir and mboxes, allowing you to prefix mailboxes
9470 names with e.g. /path/ or ~user/.
9471 Defaults to @samp{#f}.
9474 @deftypevr {@code{dovecot-configuration} parameter} boolean mmap-disable?
9475 Don't use mmap() at all. This is required if you store indexes to
9476 shared filesystems (NFS or clustered filesystem).
9477 Defaults to @samp{#f}.
9480 @deftypevr {@code{dovecot-configuration} parameter} boolean dotlock-use-excl?
9481 Rely on @samp{O_EXCL} to work when creating dotlock files. NFS
9482 supports @samp{O_EXCL} since version 3, so this should be safe to use
9483 nowadays by default.
9484 Defaults to @samp{#t}.
9487 @deftypevr {@code{dovecot-configuration} parameter} string mail-fsync
9488 When to use fsync() or fdatasync() calls:
9491 Whenever necessary to avoid losing important data
9493 Useful with e.g. NFS when write()s are delayed
9495 Never use it (best performance, but crashes can lose data).
9497 Defaults to @samp{"optimized"}.
9500 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-nfs-storage?
9501 Mail storage exists in NFS. Set this to yes to make Dovecot flush
9502 NFS caches whenever needed. If you're using only a single mail server
9504 Defaults to @samp{#f}.
9507 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-nfs-index?
9508 Mail index files also exist in NFS. Setting this to yes requires
9509 @samp{mmap-disable? #t} and @samp{fsync-disable? #f}.
9510 Defaults to @samp{#f}.
9513 @deftypevr {@code{dovecot-configuration} parameter} string lock-method
9514 Locking method for index files. Alternatives are fcntl, flock and
9515 dotlock. Dotlocking uses some tricks which may create more disk I/O
9516 than other locking methods. NFS users: flock doesn't work, remember to
9517 change @samp{mmap-disable}.
9518 Defaults to @samp{"fcntl"}.
9521 @deftypevr {@code{dovecot-configuration} parameter} file-name mail-temp-dir
9522 Directory in which LDA/LMTP temporarily stores incoming mails >128
9524 Defaults to @samp{"/tmp"}.
9527 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer first-valid-uid
9528 Valid UID range for users. This is mostly to make sure that users can't
9529 log in as daemons or other system users. Note that denying root logins is
9530 hardcoded to dovecot binary and can't be done even if @samp{first-valid-uid}
9532 Defaults to @samp{500}.
9535 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer last-valid-uid
9537 Defaults to @samp{0}.
9540 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer first-valid-gid
9541 Valid GID range for users. Users having non-valid GID as primary group ID
9542 aren't allowed to log in. If user belongs to supplementary groups with
9543 non-valid GIDs, those groups are not set.
9544 Defaults to @samp{1}.
9547 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer last-valid-gid
9549 Defaults to @samp{0}.
9552 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-max-keyword-length
9553 Maximum allowed length for mail keyword name. It's only forced when
9554 trying to create new keywords.
9555 Defaults to @samp{50}.
9558 @deftypevr {@code{dovecot-configuration} parameter} colon-separated-file-name-list valid-chroot-dirs
9559 List of directories under which chrooting is allowed for mail
9560 processes (i.e. /var/mail will allow chrooting to /var/mail/foo/bar
9561 too). This setting doesn't affect @samp{login-chroot}
9562 @samp{mail-chroot} or auth chroot settings. If this setting is empty,
9563 "/./" in home dirs are ignored. WARNING: Never add directories here
9564 which local users can modify, that may lead to root exploit. Usually
9565 this should be done only if you don't allow shell access for users.
9566 <doc/wiki/Chrooting.txt>.
9567 Defaults to @samp{()}.
9570 @deftypevr {@code{dovecot-configuration} parameter} string mail-chroot
9571 Default chroot directory for mail processes. This can be overridden
9572 for specific users in user database by giving /./ in user's home
9573 directory (e.g. /home/./user chroots into /home). Note that usually
9574 there is no real need to do chrooting, Dovecot doesn't allow users to
9575 access files outside their mail directory anyway. If your home
9576 directories are prefixed with the chroot directory, append "/." to
9577 @samp{mail-chroot}. <doc/wiki/Chrooting.txt>.
9578 Defaults to @samp{""}.
9581 @deftypevr {@code{dovecot-configuration} parameter} file-name auth-socket-path
9582 UNIX socket path to master authentication server to find users.
9583 This is used by imap (for shared users) and lda.
9584 Defaults to @samp{"/var/run/dovecot/auth-userdb"}.
9587 @deftypevr {@code{dovecot-configuration} parameter} file-name mail-plugin-dir
9588 Directory where to look up mail plugins.
9589 Defaults to @samp{"/usr/lib/dovecot"}.
9592 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mail-plugins
9593 List of plugins to load for all services. Plugins specific to IMAP,
9594 LDA, etc. are added to this list in their own .conf files.
9595 Defaults to @samp{()}.
9598 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-cache-min-mail-count
9599 The minimum number of mails in a mailbox before updates are done to
9600 cache file. This allows optimizing Dovecot's behavior to do less disk
9601 writes at the cost of more disk reads.
9602 Defaults to @samp{0}.
9605 @deftypevr {@code{dovecot-configuration} parameter} string mailbox-idle-check-interval
9606 When IDLE command is running, mailbox is checked once in a while to
9607 see if there are any new mails or other changes. This setting defines
9608 the minimum time to wait between those checks. Dovecot can also use
9609 dnotify, inotify and kqueue to find out immediately when changes
9611 Defaults to @samp{"30 secs"}.
9614 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-save-crlf?
9615 Save mails with CR+LF instead of plain LF. This makes sending those
9616 mails take less CPU, especially with sendfile() syscall with Linux and
9617 FreeBSD. But it also creates a bit more disk I/O which may just make it
9618 slower. Also note that if other software reads the mboxes/maildirs,
9619 they may handle the extra CRs wrong and cause problems.
9620 Defaults to @samp{#f}.
9623 @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-stat-dirs?
9624 By default LIST command returns all entries in maildir beginning
9625 with a dot. Enabling this option makes Dovecot return only entries
9626 which are directories. This is done by stat()ing each entry, so it
9627 causes more disk I/O.
9628 (For systems setting struct @samp{dirent->d_type} this check is free
9629 and it's done always regardless of this setting).
9630 Defaults to @samp{#f}.
9633 @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-copy-with-hardlinks?
9634 When copying a message, do it with hard links whenever possible.
9635 This makes the performance much better, and it's unlikely to have any
9637 Defaults to @samp{#t}.
9640 @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-very-dirty-syncs?
9641 Assume Dovecot is the only MUA accessing Maildir: Scan cur/
9642 directory only when its mtime changes unexpectedly or when we can't find
9644 Defaults to @samp{#f}.
9647 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mbox-read-locks
9648 Which locking methods to use for locking mbox. There are four
9653 Create <mailbox>.lock file. This is the oldest and most NFS-safe
9654 solution. If you want to use /var/mail/ like directory, the users will
9655 need write access to that directory.
9657 Same as dotlock, but if it fails because of permissions or because there
9658 isn't enough disk space, just skip it.
9660 Use this if possible. Works with NFS too if lockd is used.
9662 May not exist in all systems. Doesn't work with NFS.
9664 May not exist in all systems. Doesn't work with NFS.
9667 You can use multiple locking methods; if you do the order they're declared
9668 in is important to avoid deadlocks if other MTAs/MUAs are using multiple
9669 locking methods as well. Some operating systems don't allow using some of
9670 them simultaneously.
9673 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mbox-write-locks
9677 @deftypevr {@code{dovecot-configuration} parameter} string mbox-lock-timeout
9678 Maximum time to wait for lock (all of them) before aborting.
9679 Defaults to @samp{"5 mins"}.
9682 @deftypevr {@code{dovecot-configuration} parameter} string mbox-dotlock-change-timeout
9683 If dotlock exists but the mailbox isn't modified in any way,
9684 override the lock file after this much time.
9685 Defaults to @samp{"2 mins"}.
9688 @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-dirty-syncs?
9689 When mbox changes unexpectedly we have to fully read it to find out
9690 what changed. If the mbox is large this can take a long time. Since
9691 the change is usually just a newly appended mail, it'd be faster to
9692 simply read the new mails. If this setting is enabled, Dovecot does
9693 this but still safely fallbacks to re-reading the whole mbox file
9694 whenever something in mbox isn't how it's expected to be. The only real
9695 downside to this setting is that if some other MUA changes message
9696 flags, Dovecot doesn't notice it immediately. Note that a full sync is
9697 done with SELECT, EXAMINE, EXPUNGE and CHECK commands.
9698 Defaults to @samp{#t}.
9701 @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-very-dirty-syncs?
9702 Like @samp{mbox-dirty-syncs}, but don't do full syncs even with SELECT,
9703 EXAMINE, EXPUNGE or CHECK commands. If this is set,
9704 @samp{mbox-dirty-syncs} is ignored.
9705 Defaults to @samp{#f}.
9708 @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-lazy-writes?
9709 Delay writing mbox headers until doing a full write sync (EXPUNGE
9710 and CHECK commands and when closing the mailbox). This is especially
9711 useful for POP3 where clients often delete all mails. The downside is
9712 that our changes aren't immediately visible to other MUAs.
9713 Defaults to @samp{#t}.
9716 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mbox-min-index-size
9717 If mbox size is smaller than this (e.g. 100k), don't write index
9718 files. If an index file already exists it's still read, just not
9720 Defaults to @samp{0}.
9723 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mdbox-rotate-size
9724 Maximum dbox file size until it's rotated.
9725 Defaults to @samp{2000000}.
9728 @deftypevr {@code{dovecot-configuration} parameter} string mdbox-rotate-interval
9729 Maximum dbox file age until it's rotated. Typically in days. Day
9730 begins from midnight, so 1d = today, 2d = yesterday, etc. 0 = check
9732 Defaults to @samp{"1d"}.
9735 @deftypevr {@code{dovecot-configuration} parameter} boolean mdbox-preallocate-space?
9736 When creating new mdbox files, immediately preallocate their size to
9737 @samp{mdbox-rotate-size}. This setting currently works only in Linux
9738 with some filesystems (ext4, xfs).
9739 Defaults to @samp{#f}.
9742 @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-dir
9743 sdbox and mdbox support saving mail attachments to external files,
9744 which also allows single instance storage for them. Other backends
9745 don't support this for now.
9747 WARNING: This feature hasn't been tested much yet. Use at your own risk.
9749 Directory root where to store mail attachments. Disabled, if empty.
9750 Defaults to @samp{""}.
9753 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-attachment-min-size
9754 Attachments smaller than this aren't saved externally. It's also
9755 possible to write a plugin to disable saving specific attachments
9757 Defaults to @samp{128000}.
9760 @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-fs
9761 Filesystem backend to use for saving attachments:
9764 No SiS done by Dovecot (but this might help FS's own deduplication)
9766 SiS with immediate byte-by-byte comparison during saving
9767 @item sis-queue posix
9768 SiS with delayed comparison and deduplication.
9770 Defaults to @samp{"sis posix"}.
9773 @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-hash
9774 Hash format to use in attachment filenames. You can add any text and
9775 variables: @code{%@{md4@}}, @code{%@{md5@}}, @code{%@{sha1@}},
9776 @code{%@{sha256@}}, @code{%@{sha512@}}, @code{%@{size@}}. Variables can be
9777 truncated, e.g. @code{%@{sha256:80@}} returns only first 80 bits.
9778 Defaults to @samp{"%@{sha1@}"}.
9781 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-process-limit
9783 Defaults to @samp{100}.
9786 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-client-limit
9788 Defaults to @samp{1000}.
9791 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-vsz-limit
9792 Default VSZ (virtual memory size) limit for service processes.
9793 This is mainly intended to catch and kill processes that leak memory
9794 before they eat up everything.
9795 Defaults to @samp{256000000}.
9798 @deftypevr {@code{dovecot-configuration} parameter} string default-login-user
9799 Login user is internally used by login processes. This is the most
9800 untrusted user in Dovecot system. It shouldn't have access to anything
9802 Defaults to @samp{"dovenull"}.
9805 @deftypevr {@code{dovecot-configuration} parameter} string default-internal-user
9806 Internal user is used by unprivileged processes. It should be
9807 separate from login user, so that login processes can't disturb other
9809 Defaults to @samp{"dovecot"}.
9812 @deftypevr {@code{dovecot-configuration} parameter} string ssl?
9813 SSL/TLS support: yes, no, required. <doc/wiki/SSL.txt>.
9814 Defaults to @samp{"required"}.
9817 @deftypevr {@code{dovecot-configuration} parameter} string ssl-cert
9818 PEM encoded X.509 SSL/TLS certificate (public key).
9819 Defaults to @samp{"</etc/dovecot/default.pem"}.
9822 @deftypevr {@code{dovecot-configuration} parameter} string ssl-key
9823 PEM encoded SSL/TLS private key. The key is opened before
9824 dropping root privileges, so keep the key file unreadable by anyone but
9826 Defaults to @samp{"</etc/dovecot/private/default.pem"}.
9829 @deftypevr {@code{dovecot-configuration} parameter} string ssl-key-password
9830 If key file is password protected, give the password here.
9831 Alternatively give it when starting dovecot with -p parameter. Since
9832 this file is often world-readable, you may want to place this setting
9833 instead to a different.
9834 Defaults to @samp{""}.
9837 @deftypevr {@code{dovecot-configuration} parameter} string ssl-ca
9838 PEM encoded trusted certificate authority. Set this only if you
9839 intend to use @samp{ssl-verify-client-cert? #t}. The file should
9840 contain the CA certificate(s) followed by the matching
9841 CRL(s). (e.g. @samp{ssl-ca </etc/ssl/certs/ca.pem}).
9842 Defaults to @samp{""}.
9845 @deftypevr {@code{dovecot-configuration} parameter} boolean ssl-require-crl?
9846 Require that CRL check succeeds for client certificates.
9847 Defaults to @samp{#t}.
9850 @deftypevr {@code{dovecot-configuration} parameter} boolean ssl-verify-client-cert?
9851 Request client to send a certificate. If you also want to require
9852 it, set @samp{auth-ssl-require-client-cert? #t} in auth section.
9853 Defaults to @samp{#f}.
9856 @deftypevr {@code{dovecot-configuration} parameter} string ssl-cert-username-field
9857 Which field from certificate to use for username. commonName and
9858 x500UniqueIdentifier are the usual choices. You'll also need to set
9859 @samp{auth-ssl-username-from-cert? #t}.
9860 Defaults to @samp{"commonName"}.
9863 @deftypevr {@code{dovecot-configuration} parameter} hours ssl-parameters-regenerate
9864 How often to regenerate the SSL parameters file. Generation is
9865 quite CPU intensive operation. The value is in hours, 0 disables
9866 regeneration entirely.
9867 Defaults to @samp{168}.
9870 @deftypevr {@code{dovecot-configuration} parameter} string ssl-protocols
9871 SSL protocols to use.
9872 Defaults to @samp{"!SSLv2"}.
9875 @deftypevr {@code{dovecot-configuration} parameter} string ssl-cipher-list
9877 Defaults to @samp{"ALL:!LOW:!SSLv2:!EXP:!aNULL"}.
9880 @deftypevr {@code{dovecot-configuration} parameter} string ssl-crypto-device
9881 SSL crypto device to use, for valid values run "openssl engine".
9882 Defaults to @samp{""}.
9885 @deftypevr {@code{dovecot-configuration} parameter} string postmaster-address
9886 Address to use when sending rejection mails.
9887 Default is postmaster@@<your domain>. %d expands to recipient domain.
9888 Defaults to @samp{""}.
9891 @deftypevr {@code{dovecot-configuration} parameter} string hostname
9892 Hostname to use in various parts of sent mails (e.g. in Message-Id)
9893 and in LMTP replies. Default is the system's real hostname@@domain.
9894 Defaults to @samp{""}.
9897 @deftypevr {@code{dovecot-configuration} parameter} boolean quota-full-tempfail?
9898 If user is over quota, return with temporary failure instead of
9900 Defaults to @samp{#f}.
9903 @deftypevr {@code{dovecot-configuration} parameter} file-name sendmail-path
9904 Binary to use for sending mails.
9905 Defaults to @samp{"/usr/sbin/sendmail"}.
9908 @deftypevr {@code{dovecot-configuration} parameter} string submission-host
9909 If non-empty, send mails via this SMTP host[:port] instead of
9911 Defaults to @samp{""}.
9914 @deftypevr {@code{dovecot-configuration} parameter} string rejection-subject
9915 Subject: header to use for rejection mails. You can use the same
9916 variables as for @samp{rejection-reason} below.
9917 Defaults to @samp{"Rejected: %s"}.
9920 @deftypevr {@code{dovecot-configuration} parameter} string rejection-reason
9921 Human readable error message for rejection mails. You can use
9934 Defaults to @samp{"Your message to <%t> was automatically rejected:%n%r"}.
9937 @deftypevr {@code{dovecot-configuration} parameter} string recipient-delimiter
9938 Delimiter character between local-part and detail in email
9940 Defaults to @samp{"+"}.
9943 @deftypevr {@code{dovecot-configuration} parameter} string lda-original-recipient-header
9944 Header where the original recipient address (SMTP's RCPT TO:
9945 address) is taken from if not available elsewhere. With dovecot-lda -a
9946 parameter overrides this. A commonly used header for this is
9948 Defaults to @samp{""}.
9951 @deftypevr {@code{dovecot-configuration} parameter} boolean lda-mailbox-autocreate?
9952 Should saving a mail to a nonexistent mailbox automatically create
9954 Defaults to @samp{#f}.
9957 @deftypevr {@code{dovecot-configuration} parameter} boolean lda-mailbox-autosubscribe?
9958 Should automatically created mailboxes be also automatically
9960 Defaults to @samp{#f}.
9963 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer imap-max-line-length
9964 Maximum IMAP command line length. Some clients generate very long
9965 command lines with huge mailboxes, so you may need to raise this if you
9966 get "Too long argument" or "IMAP command line too large" errors
9968 Defaults to @samp{64000}.
9971 @deftypevr {@code{dovecot-configuration} parameter} string imap-logout-format
9972 IMAP logout format string:
9975 total number of bytes read from client
9977 total number of bytes sent to client.
9979 Defaults to @samp{"in=%i out=%o"}.
9982 @deftypevr {@code{dovecot-configuration} parameter} string imap-capability
9983 Override the IMAP CAPABILITY response. If the value begins with '+',
9984 add the given capabilities on top of the defaults (e.g. +XFOO XBAR).
9985 Defaults to @samp{""}.
9988 @deftypevr {@code{dovecot-configuration} parameter} string imap-idle-notify-interval
9989 How long to wait between "OK Still here" notifications when client
9991 Defaults to @samp{"2 mins"}.
9994 @deftypevr {@code{dovecot-configuration} parameter} string imap-id-send
9995 ID field names and values to send to clients. Using * as the value
9996 makes Dovecot use the default value. The following fields have default
9997 values currently: name, version, os, os-version, support-url,
9999 Defaults to @samp{""}.
10002 @deftypevr {@code{dovecot-configuration} parameter} string imap-id-log
10003 ID fields sent by client to log. * means everything.
10004 Defaults to @samp{""}.
10007 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list imap-client-workarounds
10008 Workarounds for various client bugs:
10011 @item delay-newmail
10012 Send EXISTS/RECENT new mail notifications only when replying to NOOP and
10013 CHECK commands. Some clients ignore them otherwise, for example OSX
10014 Mail (<v2.1). Outlook Express breaks more badly though, without this it
10015 may show user "Message no longer in server" errors. Note that OE6
10016 still breaks even with this workaround if synchronization is set to
10019 @item tb-extra-mailbox-sep
10020 Thunderbird gets somehow confused with LAYOUT=fs (mbox and dbox) and
10021 adds extra @samp{/} suffixes to mailbox names. This option causes Dovecot to
10022 ignore the extra @samp{/} instead of treating it as invalid mailbox name.
10024 @item tb-lsub-flags
10025 Show \Noselect flags for LSUB replies with LAYOUT=fs (e.g. mbox).
10026 This makes Thunderbird realize they aren't selectable and show them
10027 greyed out, instead of only later giving "not selectable" popup error.
10029 Defaults to @samp{()}.
10032 @deftypevr {@code{dovecot-configuration} parameter} string imap-urlauth-host
10033 Host allowed in URLAUTH URLs sent by client. "*" allows all.
10034 Defaults to @samp{""}.
10038 Whew! Lots of configuration options. The nice thing about it though is
10039 that GuixSD has a complete interface to Dovecot's configuration
10040 language. This allows not only a nice way to declare configurations,
10041 but also offers reflective capabilities as well: users can write code to
10042 inspect and transform configurations from within Scheme.
10044 However, it could be that you just want to get a @code{dovecot.conf} up
10045 and running. In that case, you can pass an
10046 @code{opaque-dovecot-configuration} as the @code{#:config} parameter to
10047 @code{dovecot-service}. As its name indicates, an opaque configuration
10048 does not have easy reflective capabilities.
10050 Available @code{opaque-dovecot-configuration} fields are:
10052 @deftypevr {@code{opaque-dovecot-configuration} parameter} package dovecot
10053 The dovecot package.
10056 @deftypevr {@code{opaque-dovecot-configuration} parameter} string string
10057 The contents of the @code{dovecot.conf}, as a string.
10060 For example, if your @code{dovecot.conf} is just the empty string, you
10061 could instantiate a dovecot service like this:
10064 (dovecot-service #:config
10065 (opaque-dovecot-configuration
10070 @subsubsection Web Services
10072 The @code{(gnu services web)} module provides the following service:
10074 @deffn {Scheme Procedure} nginx-service [#:nginx nginx] @
10075 [#:log-directory ``/var/log/nginx''] @
10076 [#:run-directory ``/var/run/nginx''] @
10079 Return a service that runs @var{nginx}, the nginx web server.
10081 The nginx daemon loads its runtime configuration from @var{config-file}.
10082 Log files are written to @var{log-directory} and temporary runtime data
10083 files are written to @var{run-directory}. For proper operation, these
10084 arguments should match what is in @var{config-file} to ensure that the
10085 directories are created when the service is activated.
10089 @node Various Services
10090 @subsubsection Various Services
10093 @subsubheading Lirc Service
10095 The @code{(gnu services lirc)} module provides the following service.
10097 @deffn {Scheme Procedure} lirc-service [#:lirc lirc] @
10098 [#:device #f] [#:driver #f] [#:config-file #f] @
10099 [#:extra-options '()]
10100 Return a service that runs @url{http://www.lirc.org,LIRC}, a daemon that
10101 decodes infrared signals from remote controls.
10103 Optionally, @var{device}, @var{driver} and @var{config-file}
10104 (configuration file name) may be specified. See @command{lircd} manual
10107 Finally, @var{extra-options} is a list of additional command-line options
10108 passed to @command{lircd}.
10112 @subsubheading Spice Service
10114 The @code{(gnu services spice)} module provides the following service.
10116 @deffn {Scheme Procedure} spice-vdagent-service [#:spice-vdagent]
10117 Returns a service that runs @url{http://www.spice-space.org,VDAGENT}, a daemon
10118 that enables sharing the clipboard with a vm and setting the guest display
10119 resolution when the graphical console window resizes.
10122 @subsubsection Dictionary Services
10123 The @code{(gnu services dict)} module provides the following service:
10125 @deffn {Scheme Procedure} dicod-service [#:config (dicod-configuration)]
10126 Return a service that runs the @command{dicod} daemon, an implementation
10127 of DICT server (@pxref{Dicod,,, dico, GNU Dico Manual}).
10129 The optional @var{config} argument specifies the configuration for
10130 @command{dicod}, which should be a @code{<dicod-configuration>} object, by
10131 default it serves the GNU Collaborative International Dictonary of English.
10133 You can add @command{open localhost} to your @file{~/.dico} file to make
10134 @code{localhost} the default server for @command{dico} client
10135 (@pxref{Initialization File,,, dico, GNU Dico Manual}).
10138 @deftp {Data Type} dicod-configuration
10139 Data type representing the configuration of dicod.
10142 @item @code{dico} (default: @var{dico})
10143 Package object of the GNU Dico dictionary server.
10145 @item @code{interfaces} (default: @var{'("localhost")})
10146 This is the list of IP addresses and ports and possibly socket file
10147 names to listen to (@pxref{Server Settings, @code{listen} directive,,
10148 dico, GNU Dico Manual}).
10150 @item @code{databases} (default: @var{(list %dicod-database:gcide)})
10151 List of @code{<dicod-database>} objects denoting dictionaries to be served.
10155 @deftp {Data Type} dicod-database
10156 Data type representing a dictionary database.
10160 Name of the database, will be used in DICT commands.
10162 @item @code{module}
10163 Name of the dicod module used by this database
10164 (@pxref{Modules,,, dico, GNU Dico Manual}).
10166 @item @code{options}
10167 List of strings or gexps representing the arguments for the module handler
10168 (@pxref{Handlers,,, dico, GNU Dico Manual}).
10172 @defvr {Scheme Variable} %dicod-database:gcide
10173 A @code{<dicod-database>} object serving the GNU Collaborative International
10174 Dictonary of English using the @code{gcide} package.
10177 @node Setuid Programs
10178 @subsection Setuid Programs
10180 @cindex setuid programs
10181 Some programs need to run with ``root'' privileges, even when they are
10182 launched by unprivileged users. A notorious example is the
10183 @command{passwd} program, which users can run to change their
10184 password, and which needs to access the @file{/etc/passwd} and
10185 @file{/etc/shadow} files---something normally restricted to root, for
10186 obvious security reasons. To address that, these executables are
10187 @dfn{setuid-root}, meaning that they always run with root privileges
10188 (@pxref{How Change Persona,,, libc, The GNU C Library Reference Manual},
10189 for more info about the setuid mechanism.)
10191 The store itself @emph{cannot} contain setuid programs: that would be a
10192 security issue since any user on the system can write derivations that
10193 populate the store (@pxref{The Store}). Thus, a different mechanism is
10194 used: instead of changing the setuid bit directly on files that are in
10195 the store, we let the system administrator @emph{declare} which programs
10196 should be setuid root.
10198 The @code{setuid-programs} field of an @code{operating-system}
10199 declaration contains a list of G-expressions denoting the names of
10200 programs to be setuid-root (@pxref{Using the Configuration System}).
10201 For instance, the @command{passwd} program, which is part of the Shadow
10202 package, can be designated by this G-expression (@pxref{G-Expressions}):
10205 #~(string-append #$shadow "/bin/passwd")
10208 A default set of setuid programs is defined by the
10209 @code{%setuid-programs} variable of the @code{(gnu system)} module.
10211 @defvr {Scheme Variable} %setuid-programs
10212 A list of G-expressions denoting common programs that are setuid-root.
10214 The list includes commands such as @command{passwd}, @command{ping},
10215 @command{su}, and @command{sudo}.
10218 Under the hood, the actual setuid programs are created in the
10219 @file{/run/setuid-programs} directory at system activation time. The
10220 files in this directory refer to the ``real'' binaries, which are in the
10223 @node X.509 Certificates
10224 @subsection X.509 Certificates
10226 @cindex HTTPS, certificates
10227 @cindex X.509 certificates
10229 Web servers available over HTTPS (that is, HTTP over the transport-layer
10230 security mechanism, TLS) send client programs an @dfn{X.509 certificate}
10231 that the client can then use to @emph{authenticate} the server. To do
10232 that, clients verify that the server's certificate is signed by a
10233 so-called @dfn{certificate authority} (CA). But to verify the CA's
10234 signature, clients must have first acquired the CA's certificate.
10236 Web browsers such as GNU@tie{}IceCat include their own set of CA
10237 certificates, such that they are able to verify CA signatures
10240 However, most other programs that can talk HTTPS---@command{wget},
10241 @command{git}, @command{w3m}, etc.---need to be told where CA
10242 certificates can be found.
10244 @cindex @code{nss-certs}
10245 In GuixSD, this is done by adding a package that provides certificates
10246 to the @code{packages} field of the @code{operating-system} declaration
10247 (@pxref{operating-system Reference}). GuixSD includes one such package,
10248 @code{nss-certs}, which is a set of CA certificates provided as part of
10249 Mozilla's Network Security Services.
10251 Note that it is @emph{not} part of @var{%base-packages}, so you need to
10252 explicitly add it. The @file{/etc/ssl/certs} directory, which is where
10253 most applications and libraries look for certificates by default, points
10254 to the certificates installed globally.
10256 Unprivileged users, including users of Guix on a foreign distro,
10257 can also install their own certificate package in
10258 their profile. A number of environment variables need to be defined so
10259 that applications and libraries know where to find them. Namely, the
10260 OpenSSL library honors the @code{SSL_CERT_DIR} and @code{SSL_CERT_FILE}
10261 variables. Some applications add their own environment variables; for
10262 instance, the Git version control system honors the certificate bundle
10263 pointed to by the @code{GIT_SSL_CAINFO} environment variable. Thus, you
10264 would typically run something like:
10267 $ guix package -i nss-certs
10268 $ export SSL_CERT_DIR="$HOME/.guix-profile/etc/ssl/certs"
10269 $ export SSL_CERT_FILE="$HOME/.guix-profile/etc/ssl/certs/ca-certificates.crt"
10270 $ export GIT_SSL_CAINFO="$SSL_CERT_FILE"
10273 @node Name Service Switch
10274 @subsection Name Service Switch
10276 @cindex name service switch
10278 The @code{(gnu system nss)} module provides bindings to the
10279 configuration file of the libc @dfn{name service switch} or @dfn{NSS}
10280 (@pxref{NSS Configuration File,,, libc, The GNU C Library Reference
10281 Manual}). In a nutshell, the NSS is a mechanism that allows libc to be
10282 extended with new ``name'' lookup methods for system databases, which
10283 includes host names, service names, user accounts, and more (@pxref{Name
10284 Service Switch, System Databases and Name Service Switch,, libc, The GNU
10285 C Library Reference Manual}).
10287 The NSS configuration specifies, for each system database, which lookup
10288 method is to be used, and how the various methods are chained
10289 together---for instance, under which circumstances NSS should try the
10290 next method in the list. The NSS configuration is given in the
10291 @code{name-service-switch} field of @code{operating-system} declarations
10292 (@pxref{operating-system Reference, @code{name-service-switch}}).
10295 @cindex .local, host name lookup
10296 As an example, the declaration below configures the NSS to use the
10297 @uref{http://0pointer.de/lennart/projects/nss-mdns/, @code{nss-mdns}
10298 back-end}, which supports host name lookups over multicast DNS (mDNS)
10299 for host names ending in @code{.local}:
10302 (name-service-switch
10303 (hosts (list %files ;first, check /etc/hosts
10305 ;; If the above did not succeed, try
10306 ;; with 'mdns_minimal'.
10308 (name "mdns_minimal")
10310 ;; 'mdns_minimal' is authoritative for
10311 ;; '.local'. When it returns "not found",
10312 ;; no need to try the next methods.
10313 (reaction (lookup-specification
10314 (not-found => return))))
10316 ;; Then fall back to DNS.
10320 ;; Finally, try with the "full" 'mdns'.
10325 Do not worry: the @code{%mdns-host-lookup-nss} variable (see below)
10326 contains this configuration, so you will not have to type it if all you
10327 want is to have @code{.local} host lookup working.
10329 Note that, in this case, in addition to setting the
10330 @code{name-service-switch} of the @code{operating-system} declaration,
10331 you also need to use @code{avahi-service} (@pxref{Networking Services,
10332 @code{avahi-service}}), or @var{%desktop-services}, which includes it
10333 (@pxref{Desktop Services}). Doing this makes @code{nss-mdns} accessible
10334 to the name service cache daemon (@pxref{Base Services,
10335 @code{nscd-service}}).
10337 For convenience, the following variables provide typical NSS
10340 @defvr {Scheme Variable} %default-nss
10341 This is the default name service switch configuration, a
10342 @code{name-service-switch} object.
10345 @defvr {Scheme Variable} %mdns-host-lookup-nss
10346 This is the name service switch configuration with support for host name
10347 lookup over multicast DNS (mDNS) for host names ending in @code{.local}.
10350 The reference for name service switch configuration is given below. It
10351 is a direct mapping of the configuration file format of the C library , so
10352 please refer to the C library manual for more information (@pxref{NSS
10353 Configuration File,,, libc, The GNU C Library Reference Manual}).
10354 Compared to the configuration file format of libc NSS, it has the advantage
10355 not only of adding this warm parenthetic feel that we like, but also
10356 static checks: you will know about syntax errors and typos as soon as you
10357 run @command{guix system}.
10359 @deftp {Data Type} name-service-switch
10361 This is the data type representation the configuration of libc's name
10362 service switch (NSS). Each field below represents one of the supported
10379 The system databases handled by the NSS. Each of these fields must be a
10380 list of @code{<name-service>} objects (see below).
10384 @deftp {Data Type} name-service
10386 This is the data type representing an actual name service and the
10387 associated lookup action.
10391 A string denoting the name service (@pxref{Services in the NSS
10392 configuration,,, libc, The GNU C Library Reference Manual}).
10394 Note that name services listed here must be visible to nscd. This is
10395 achieved by passing the @code{#:name-services} argument to
10396 @code{nscd-service} the list of packages providing the needed name
10397 services (@pxref{Base Services, @code{nscd-service}}).
10400 An action specified using the @code{lookup-specification} macro
10401 (@pxref{Actions in the NSS configuration,,, libc, The GNU C Library
10402 Reference Manual}). For example:
10405 (lookup-specification (unavailable => continue)
10406 (success => return))
10411 @node Initial RAM Disk
10412 @subsection Initial RAM Disk
10414 @cindex initial RAM disk (initrd)
10415 @cindex initrd (initial RAM disk)
10416 For bootstrapping purposes, the Linux-Libre kernel is passed an
10417 @dfn{initial RAM disk}, or @dfn{initrd}. An initrd contains a temporary
10418 root file system as well as an initialization script. The latter is
10419 responsible for mounting the real root file system, and for loading any
10420 kernel modules that may be needed to achieve that.
10422 The @code{initrd} field of an @code{operating-system} declaration allows
10423 you to specify which initrd you would like to use. The @code{(gnu
10424 system linux-initrd)} module provides two ways to build an initrd: the
10425 high-level @code{base-initrd} procedure, and the low-level
10426 @code{expression->initrd} procedure.
10428 The @code{base-initrd} procedure is intended to cover most common uses.
10429 For example, if you want to add a bunch of kernel modules to be loaded
10430 at boot time, you can define the @code{initrd} field of the operating
10431 system declaration like this:
10434 (initrd (lambda (file-systems . rest)
10435 ;; Create a standard initrd that has modules "foo.ko"
10436 ;; and "bar.ko", as well as their dependencies, in
10437 ;; addition to the modules available by default.
10438 (apply base-initrd file-systems
10439 #:extra-modules '("foo" "bar")
10443 The @code{base-initrd} procedure also handles common use cases that
10444 involves using the system as a QEMU guest, or as a ``live'' system with
10445 volatile root file system.
10447 The initial RAM disk produced by @code{base-initrd} honors several
10448 options passed on the Linux kernel command line (that is, arguments
10449 passed @i{via} the @code{linux} command of GRUB, or the
10450 @code{-append} option) of QEMU, notably:
10453 @item --load=@var{boot}
10454 Tell the initial RAM disk to load @var{boot}, a file containing a Scheme
10455 program, once it has mounted the root file system.
10457 GuixSD uses this option to yield control to a boot program that runs the
10458 service activation programs and then spawns the GNU@tie{}Shepherd, the
10459 initialization system.
10461 @item --root=@var{root}
10462 Mount @var{root} as the root file system. @var{root} can be a
10463 device name like @code{/dev/sda1}, a partition label, or a partition
10466 @item --system=@var{system}
10467 Have @file{/run/booted-system} and @file{/run/current-system} point to
10470 @item modprobe.blacklist=@var{modules}@dots{}
10471 @cindex module, black-listing
10472 @cindex black list, of kernel modules
10473 Instruct the initial RAM disk as well as the @command{modprobe} command
10474 (from the kmod package) to refuse to load @var{modules}. @var{modules}
10475 must be a comma-separated list of module names---e.g.,
10476 @code{usbkbd,9pnet}.
10479 Start a read-eval-print loop (REPL) from the initial RAM disk before it
10480 tries to load kernel modules and to mount the root file system. Our
10481 marketing team calls it @dfn{boot-to-Guile}. The Schemer in you will
10482 love it. @xref{Using Guile Interactively,,, guile, GNU Guile Reference
10483 Manual}, for more information on Guile's REPL.
10487 Now that you know all the features that initial RAM disks produced by
10488 @code{base-initrd} provide, here is how to use it and customize it
10491 @deffn {Monadic Procedure} base-initrd @var{file-systems} @
10492 [#:qemu-networking? #f] [#:virtio? #t] [#:volatile-root? #f] @
10493 [#:extra-modules '()] [#:mapped-devices '()]
10494 Return a monadic derivation that builds a generic initrd. @var{file-systems} is
10495 a list of file systems to be mounted by the initrd, possibly in addition to
10496 the root file system specified on the kernel command line via @code{--root}.
10497 @var{mapped-devices} is a list of device mappings to realize before
10498 @var{file-systems} are mounted (@pxref{Mapped Devices}).
10500 When @var{qemu-networking?} is true, set up networking with the standard QEMU
10501 parameters. When @var{virtio?} is true, load additional modules so that the
10502 initrd can be used as a QEMU guest with para-virtualized I/O drivers.
10504 When @var{volatile-root?} is true, the root file system is writable but any changes
10507 The initrd is automatically populated with all the kernel modules necessary
10508 for @var{file-systems} and for the given options. However, additional kernel
10509 modules can be listed in @var{extra-modules}. They will be added to the initrd, and
10510 loaded at boot time in the order in which they appear.
10513 Needless to say, the initrds we produce and use embed a
10514 statically-linked Guile, and the initialization program is a Guile
10515 program. That gives a lot of flexibility. The
10516 @code{expression->initrd} procedure builds such an initrd, given the
10517 program to run in that initrd.
10519 @deffn {Monadic Procedure} expression->initrd @var{exp} @
10520 [#:guile %guile-static-stripped] [#:name "guile-initrd"]
10521 Return a derivation that builds a Linux initrd (a gzipped cpio archive)
10522 containing @var{guile} and that evaluates @var{exp}, a G-expression,
10523 upon booting. All the derivations referenced by @var{exp} are
10524 automatically copied to the initrd.
10527 @node GRUB Configuration
10528 @subsection GRUB Configuration
10531 @cindex boot loader
10533 The operating system uses GNU@tie{}GRUB as its boot loader
10534 (@pxref{Overview, overview of GRUB,, grub, GNU GRUB Manual}). It is
10535 configured using a @code{grub-configuration} declaration. This data type
10536 is exported by the @code{(gnu system grub)} module and described below.
10538 @deftp {Data Type} grub-configuration
10539 The type of a GRUB configuration declaration.
10543 @item @code{device}
10544 This is a string denoting the boot device. It must be a device name
10545 understood by the @command{grub-install} command, such as
10546 @code{/dev/sda} or @code{(hd0)} (@pxref{Invoking grub-install,,, grub,
10549 @item @code{menu-entries} (default: @code{()})
10550 A possibly empty list of @code{menu-entry} objects (see below), denoting
10551 entries to appear in the GRUB boot menu, in addition to the current
10552 system entry and the entry pointing to previous system generations.
10554 @item @code{default-entry} (default: @code{0})
10555 The index of the default boot menu entry. Index 0 is for the entry of the
10558 @item @code{timeout} (default: @code{5})
10559 The number of seconds to wait for keyboard input before booting. Set to
10560 0 to boot immediately, and to -1 to wait indefinitely.
10562 @item @code{theme} (default: @var{%default-theme})
10563 The @code{grub-theme} object describing the theme to use.
10568 Should you want to list additional boot menu entries @i{via} the
10569 @code{menu-entries} field above, you will need to create them with the
10570 @code{menu-entry} form:
10572 @deftp {Data Type} menu-entry
10573 The type of an entry in the GRUB boot menu.
10578 The label to show in the menu---e.g., @code{"GNU"}.
10581 The Linux kernel to boot.
10583 @item @code{linux-arguments} (default: @code{()})
10584 The list of extra Linux kernel command-line arguments---e.g.,
10585 @code{("console=ttyS0")}.
10587 @item @code{initrd}
10588 A G-Expression or string denoting the file name of the initial RAM disk
10589 to use (@pxref{G-Expressions}).
10594 @c FIXME: Write documentation once it's stable.
10595 Themes are created using the @code{grub-theme} form, which is not
10598 @defvr {Scheme Variable} %default-theme
10599 This is the default GRUB theme used by the operating system, with a
10600 fancy background image displaying the GNU and Guix logos.
10604 @node Invoking guix system
10605 @subsection Invoking @code{guix system}
10607 Once you have written an operating system declaration as seen in the
10608 previous section, it can be @dfn{instantiated} using the @command{guix
10609 system} command. The synopsis is:
10612 guix system @var{options}@dots{} @var{action} @var{file}
10615 @var{file} must be the name of a file containing an
10616 @code{operating-system} declaration. @var{action} specifies how the
10617 operating system is instantiated. Currently the following values are
10622 Build the operating system described in @var{file}, activate it, and
10623 switch to it@footnote{This action is usable only on systems already
10626 This effects all the configuration specified in @var{file}: user
10627 accounts, system services, global package list, setuid programs, etc.
10628 The command starts system services specified in @var{file} that are not
10629 currently running; if a service is currently running, it does not
10630 attempt to upgrade it since this would not be possible without stopping it
10633 It also adds a GRUB menu entry for the new OS configuration, and moves
10634 entries for older configurations to a submenu---unless
10635 @option{--no-grub} is passed.
10638 @c The paragraph below refers to the problem discussed at
10639 @c <http://lists.gnu.org/archive/html/guix-devel/2014-08/msg00057.html>.
10640 It is highly recommended to run @command{guix pull} once before you run
10641 @command{guix system reconfigure} for the first time (@pxref{Invoking
10642 guix pull}). Failing to do that you would see an older version of Guix
10643 once @command{reconfigure} has completed.
10647 Build the derivation of the operating system, which includes all the
10648 configuration files and programs needed to boot and run the system.
10649 This action does not actually install anything.
10652 Populate the given directory with all the files necessary to run the
10653 operating system specified in @var{file}. This is useful for first-time
10654 installations of GuixSD. For instance:
10657 guix system init my-os-config.scm /mnt
10660 copies to @file{/mnt} all the store items required by the configuration
10661 specified in @file{my-os-config.scm}. This includes configuration
10662 files, packages, and so on. It also creates other essential files
10663 needed for the system to operate correctly---e.g., the @file{/etc},
10664 @file{/var}, and @file{/run} directories, and the @file{/bin/sh} file.
10666 This command also installs GRUB on the device specified in
10667 @file{my-os-config}, unless the @option{--no-grub} option was passed.
10670 @cindex virtual machine
10672 @anchor{guix system vm}
10673 Build a virtual machine that contains the operating system declared in
10674 @var{file}, and return a script to run that virtual machine (VM).
10675 Arguments given to the script are passed to QEMU.
10677 The VM shares its store with the host system.
10679 Additional file systems can be shared between the host and the VM using
10680 the @code{--share} and @code{--expose} command-line options: the former
10681 specifies a directory to be shared with write access, while the latter
10682 provides read-only access to the shared directory.
10684 The example below creates a VM in which the user's home directory is
10685 accessible read-only, and where the @file{/exchange} directory is a
10686 read-write mapping of @file{$HOME/tmp} on the host:
10689 guix system vm my-config.scm \
10690 --expose=$HOME --share=$HOME/tmp=/exchange
10693 On GNU/Linux, the default is to boot directly to the kernel; this has
10694 the advantage of requiring only a very tiny root disk image since the
10695 store of the host can then be mounted.
10697 The @code{--full-boot} option forces a complete boot sequence, starting
10698 with the bootloader. This requires more disk space since a root image
10699 containing at least the kernel, initrd, and bootloader data files must
10700 be created. The @code{--image-size} option can be used to specify the
10705 Return a virtual machine or disk image of the operating system declared
10706 in @var{file} that stands alone. Use the @option{--image-size} option
10707 to specify the size of the image.
10709 When using @code{vm-image}, the returned image is in qcow2 format, which
10710 the QEMU emulator can efficiently use. @xref{Running GuixSD in a VM},
10711 for more information on how to run the image in a virtual machine.
10713 When using @code{disk-image}, a raw disk image is produced; it can be
10714 copied as is to a USB stick, for instance. Assuming @code{/dev/sdc} is
10715 the device corresponding to a USB stick, one can copy the image to it
10716 using the following command:
10719 # dd if=$(guix system disk-image my-os.scm) of=/dev/sdc
10723 Return a script to run the operating system declared in @var{file}
10724 within a container. Containers are a set of lightweight isolation
10725 mechanisms provided by the kernel Linux-libre. Containers are
10726 substantially less resource-demanding than full virtual machines since
10727 the kernel, shared objects, and other resources can be shared with the
10728 host system; this also means they provide thinner isolation.
10730 Currently, the script must be run as root in order to support more than
10731 a single user and group. The container shares its store with the host
10734 As with the @code{vm} action (@pxref{guix system vm}), additional file
10735 systems to be shared between the host and container can be specified
10736 using the @option{--share} and @option{--expose} options:
10739 guix system container my-config.scm \
10740 --expose=$HOME --share=$HOME/tmp=/exchange
10744 This option requires Linux-libre 3.19 or newer.
10749 @var{options} can contain any of the common build options (@pxref{Common
10750 Build Options}). In addition, @var{options} can contain one of the
10754 @item --system=@var{system}
10755 @itemx -s @var{system}
10756 Attempt to build for @var{system} instead of the host system type.
10757 This works as per @command{guix build} (@pxref{Invoking guix build}).
10761 Return the derivation file name of the given operating system without
10764 @item --image-size=@var{size}
10765 For the @code{vm-image} and @code{disk-image} actions, create an image
10766 of the given @var{size}. @var{size} may be a number of bytes, or it may
10767 include a unit as a suffix (@pxref{Block size, size specifications,,
10768 coreutils, GNU Coreutils}).
10770 @item --on-error=@var{strategy}
10771 Apply @var{strategy} when an error occurs when reading @var{file}.
10772 @var{strategy} may be one of the following:
10775 @item nothing-special
10776 Report the error concisely and exit. This is the default strategy.
10779 Likewise, but also display a backtrace.
10782 Report the error and enter Guile's debugger. From there, you can run
10783 commands such as @code{,bt} to get a backtrace, @code{,locals} to
10784 display local variable values, and more generally inspect the state of the
10785 program. @xref{Debug Commands,,, guile, GNU Guile Reference Manual}, for
10786 a list of available debugging commands.
10791 All the actions above, except @code{build} and @code{init},
10792 can use KVM support in the Linux-libre kernel. Specifically, if the
10793 machine has hardware virtualization support, the corresponding
10794 KVM kernel module should be loaded, and the @file{/dev/kvm} device node
10795 must exist and be readable and writable by the user and by the
10796 build users of the daemon (@pxref{Build Environment Setup}).
10799 Once you have built, configured, re-configured, and re-re-configured
10800 your GuixSD installation, you may find it useful to list the operating
10801 system generations available on disk---and that you can choose from the
10806 @item list-generations
10807 List a summary of each generation of the operating system available on
10808 disk, in a human-readable way. This is similar to the
10809 @option{--list-generations} option of @command{guix package}
10810 (@pxref{Invoking guix package}).
10812 Optionally, one can specify a pattern, with the same syntax that is used
10813 in @command{guix package --list-generations}, to restrict the list of
10814 generations displayed. For instance, the following command displays
10815 generations that are up to 10 days old:
10818 $ guix system list-generations 10d
10823 The @command{guix system} command has even more to offer! The following
10824 sub-commands allow you to visualize how your system services relate to
10827 @anchor{system-extension-graph}
10830 @item extension-graph
10831 Emit in Dot/Graphviz format to standard output the @dfn{service
10832 extension graph} of the operating system defined in @var{file}
10833 (@pxref{Service Composition}, for more information on service
10839 $ guix system extension-graph @var{file} | dot -Tpdf > services.pdf
10842 produces a PDF file showing the extension relations among services.
10844 @anchor{system-shepherd-graph}
10845 @item shepherd-graph
10846 Emit in Dot/Graphviz format to standard output the @dfn{dependency
10847 graph} of shepherd services of the operating system defined in
10848 @var{file}. @xref{Shepherd Services}, for more information and for an
10853 @node Running GuixSD in a VM
10854 @subsection Running GuixSD in a Virtual Machine
10856 One way to run GuixSD in a virtual machine (VM) is to build a GuixSD
10857 virtual machine image using @command{guix system vm-image}
10858 (@pxref{Invoking guix system}). The returned image is in qcow2 format,
10859 which the @uref{http://qemu.org/, QEMU emulator} can efficiently use.
10861 To run the image in QEMU, copy it out of the store (@pxref{The Store})
10862 and give yourself permission to write to the copy. When invoking QEMU,
10863 you must choose a system emulator that is suitable for your hardware
10864 platform. Here is a minimal QEMU invocation that will boot the result
10865 of @command{guix system vm-image} on x86_64 hardware:
10868 $ qemu-system-x86_64 \
10869 -net user -net nic,model=virtio \
10870 -enable-kvm -m 256 /tmp/qemu-image
10873 Here is what each of these options means:
10876 @item qemu-system-x86_64
10877 This specifies the hardware platform to emulate. This should match the
10881 Enable the unprivileged user-mode network stack. The guest OS can
10882 access the host but not vice versa. This is the simplest way to get the
10883 guest OS online. If you do not choose a network stack, the boot will
10886 @item -net nic,model=virtio
10887 You must create a network interface of a given model. If you do not
10888 create a NIC, the boot will fail. Assuming your hardware platform is
10889 x86_64, you can get a list of available NIC models by running
10890 @command{qemu-system-x86_64 -net nic,model=help}.
10893 If your system has hardware virtualization extensions, enabling the
10894 virtual machine support (KVM) of the Linux kernel will make things run
10898 RAM available to the guest OS, in mebibytes. Defaults to 128@tie{}MiB,
10899 which may be insufficient for some operations.
10901 @item /tmp/qemu-image
10902 The file name of the qcow2 image.
10905 @node Defining Services
10906 @subsection Defining Services
10908 The previous sections show the available services and how one can combine
10909 them in an @code{operating-system} declaration. But how do we define
10910 them in the first place? And what is a service anyway?
10913 * Service Composition:: The model for composing services.
10914 * Service Types and Services:: Types and services.
10915 * Service Reference:: API reference.
10916 * Shepherd Services:: A particular type of service.
10919 @node Service Composition
10920 @subsubsection Service Composition
10924 Here we define a @dfn{service} as, broadly, something that extends the
10925 functionality of the operating system. Often a service is a process---a
10926 @dfn{daemon}---started when the system boots: a secure shell server, a
10927 Web server, the Guix build daemon, etc. Sometimes a service is a daemon
10928 whose execution can be triggered by another daemon---e.g., an FTP server
10929 started by @command{inetd} or a D-Bus service activated by
10930 @command{dbus-daemon}. Occasionally, a service does not map to a
10931 daemon. For instance, the ``account'' service collects user accounts
10932 and makes sure they exist when the system runs; the ``udev'' service
10933 collects device management rules and makes them available to the eudev
10934 daemon; the @file{/etc} service populates the @file{/etc} directory
10937 @cindex service extensions
10938 GuixSD services are connected by @dfn{extensions}. For instance, the
10939 secure shell service @emph{extends} the Shepherd---the GuixSD
10940 initialization system, running as PID@tie{}1---by giving it the command
10941 lines to start and stop the secure shell daemon (@pxref{Networking
10942 Services, @code{lsh-service}}); the UPower service extends the D-Bus
10943 service by passing it its @file{.service} specification, and extends the
10944 udev service by passing it device management rules (@pxref{Desktop
10945 Services, @code{upower-service}}); the Guix daemon service extends the
10946 Shepherd by passing it the command lines to start and stop the daemon,
10947 and extends the account service by passing it a list of required build
10948 user accounts (@pxref{Base Services}).
10950 All in all, services and their ``extends'' relations form a directed
10951 acyclic graph (DAG). If we represent services as boxes and extensions
10952 as arrows, a typical system might provide something like this:
10954 @image{images/service-graph,,5in,Typical service extension graph.}
10956 @cindex system service
10957 At the bottom, we see the @dfn{system service}, which produces the
10958 directory containing everything to run and boot the system, as returned
10959 by the @command{guix system build} command. @xref{Service Reference},
10960 to learn about the other service types shown here.
10961 @xref{system-extension-graph, the @command{guix system extension-graph}
10962 command}, for information on how to generate this representation for a
10963 particular operating system definition.
10965 @cindex service types
10966 Technically, developers can define @dfn{service types} to express these
10967 relations. There can be any number of services of a given type on the
10968 system---for instance, a system running two instances of the GNU secure
10969 shell server (lsh) has two instances of @var{lsh-service-type}, with
10970 different parameters.
10972 The following section describes the programming interface for service
10973 types and services.
10975 @node Service Types and Services
10976 @subsubsection Service Types and Services
10978 A @dfn{service type} is a node in the DAG described above. Let us start
10979 with a simple example, the service type for the Guix build daemon
10980 (@pxref{Invoking guix-daemon}):
10983 (define guix-service-type
10987 (list (service-extension shepherd-root-service-type guix-shepherd-service)
10988 (service-extension account-service-type guix-accounts)
10989 (service-extension activation-service-type guix-activation)))))
10993 It defines two things:
10997 A name, whose sole purpose is to make inspection and debugging easier.
11000 A list of @dfn{service extensions}, where each extension designates the
11001 target service type and a procedure that, given the parameters of the
11002 service, returns a list of objects to extend the service of that type.
11004 Every service type has at least one service extension. The only
11005 exception is the @dfn{boot service type}, which is the ultimate service.
11008 In this example, @var{guix-service-type} extends three services:
11011 @item shepherd-root-service-type
11012 The @var{guix-shepherd-service} procedure defines how the Shepherd
11013 service is extended. Namely, it returns a @code{<shepherd-service>}
11014 object that defines how @command{guix-daemon} is started and stopped
11015 (@pxref{Shepherd Services}).
11017 @item account-service-type
11018 This extension for this service is computed by @var{guix-accounts},
11019 which returns a list of @code{user-group} and @code{user-account}
11020 objects representing the build user accounts (@pxref{Invoking
11023 @item activation-service-type
11024 Here @var{guix-activation} is a procedure that returns a gexp, which is
11025 a code snippet to run at ``activation time''---e.g., when the service is
11029 A service of this type is instantiated like this:
11032 (service guix-service-type
11033 (guix-configuration
11035 (use-substitutes? #f)))
11038 The second argument to the @code{service} form is a value representing
11039 the parameters of this specific service instance.
11040 @xref{guix-configuration-type, @code{guix-configuration}}, for
11041 information about the @code{guix-configuration} data type.
11043 @var{guix-service-type} is quite simple because it extends other
11044 services but is not extensible itself.
11046 @c @subsubsubsection Extensible Service Types
11048 The service type for an @emph{extensible} service looks like this:
11051 (define udev-service-type
11052 (service-type (name 'udev)
11054 (list (service-extension shepherd-root-service-type
11055 udev-shepherd-service)))
11057 (compose concatenate) ;concatenate the list of rules
11058 (extend (lambda (config rules)
11060 (($ <udev-configuration> udev initial-rules)
11061 (udev-configuration
11062 (udev udev) ;the udev package to use
11063 (rules (append initial-rules rules)))))))))
11066 This is the service type for the
11067 @uref{https://wiki.gentoo.org/wiki/Project:Eudev, eudev device
11068 management daemon}. Compared to the previous example, in addition to an
11069 extension of @var{shepherd-root-service-type}, we see two new fields:
11073 This is the procedure to @dfn{compose} the list of extensions to
11074 services of this type.
11076 Services can extend the udev service by passing it lists of rules; we
11077 compose those extensions simply by concatenating them.
11080 This procedure defines how the value of the service is @dfn{extended} with
11081 the composition of the extensions.
11083 Udev extensions are composed into a list of rules, but the udev service
11084 value is itself a @code{<udev-configuration>} record. So here, we
11085 extend that record by appending the list of rules it contains to the
11086 list of contributed rules.
11089 There can be only one instance of an extensible service type such as
11090 @var{udev-service-type}. If there were more, the
11091 @code{service-extension} specifications would be ambiguous.
11093 Still here? The next section provides a reference of the programming
11094 interface for services.
11096 @node Service Reference
11097 @subsubsection Service Reference
11099 We have seen an overview of service types (@pxref{Service Types and
11100 Services}). This section provides a reference on how to manipulate
11101 services and service types. This interface is provided by the
11102 @code{(gnu services)} module.
11104 @deffn {Scheme Procedure} service @var{type} @var{value}
11105 Return a new service of @var{type}, a @code{<service-type>} object (see
11106 below.) @var{value} can be any object; it represents the parameters of
11107 this particular service instance.
11110 @deffn {Scheme Procedure} service? @var{obj}
11111 Return true if @var{obj} is a service.
11114 @deffn {Scheme Procedure} service-kind @var{service}
11115 Return the type of @var{service}---i.e., a @code{<service-type>} object.
11118 @deffn {Scheme Procedure} service-parameters @var{service}
11119 Return the value associated with @var{service}. It represents its
11123 Here is an example of how a service is created and manipulated:
11127 (service nginx-service-type
11128 (nginx-configuration
11130 (log-directory log-directory)
11131 (run-directory run-directory)
11132 (file config-file))))
11137 (eq? (service-kind s) nginx-service-type)
11141 The @code{modify-services} form provides a handy way to change the
11142 parameters of some of the services of a list such as
11143 @var{%base-services} (@pxref{Base Services, @code{%base-services}}). It
11144 evaluates to a list of services. Of course, you could always use
11145 standard list combinators such as @code{map} and @code{fold} to do that
11146 (@pxref{SRFI-1, List Library,, guile, GNU Guile Reference Manual});
11147 @code{modify-services} simply provides a more concise form for this
11150 @deffn {Scheme Syntax} modify-services @var{services} @
11151 (@var{type} @var{variable} => @var{body}) @dots{}
11153 Modify the services listed in @var{services} according to the given
11154 clauses. Each clause has the form:
11157 (@var{type} @var{variable} => @var{body})
11160 where @var{type} is a service type---e.g.,
11161 @code{guix-service-type}---and @var{variable} is an identifier that is
11162 bound within the @var{body} to the service parameters---e.g., a
11163 @code{guix-configuration} instance---of the original service of that
11166 The @var{body} should evaluate to the new service parameters, which will
11167 be used to configure the new service. This new service will replace the
11168 original in the resulting list. Because a service's service parameters
11169 are created using @code{define-record-type*}, you can write a succinct
11170 @var{body} that evaluates to the new service parameters by using the
11171 @code{inherit} feature that @code{define-record-type*} provides.
11173 @xref{Using the Configuration System}, for example usage.
11177 Next comes the programming interface for service types. This is
11178 something you want to know when writing new service definitions, but not
11179 necessarily when simply looking for ways to customize your
11180 @code{operating-system} declaration.
11182 @deftp {Data Type} service-type
11183 @cindex service type
11184 This is the representation of a @dfn{service type} (@pxref{Service Types
11189 This is a symbol, used only to simplify inspection and debugging.
11191 @item @code{extensions}
11192 A non-empty list of @code{<service-extension>} objects (see below).
11194 @item @code{compose} (default: @code{#f})
11195 If this is @code{#f}, then the service type denotes services that cannot
11196 be extended---i.e., services that do not receive ``values'' from other
11199 Otherwise, it must be a one-argument procedure. The procedure is called
11200 by @code{fold-services} and is passed a list of values collected from
11201 extensions. It must return a value that is a valid parameter value for
11202 the service instance.
11204 @item @code{extend} (default: @code{#f})
11205 If this is @code{#f}, services of this type cannot be extended.
11207 Otherwise, it must be a two-argument procedure: @code{fold-services}
11208 calls it, passing it the initial value of the service as the first argument
11209 and the result of applying @code{compose} to the extension values as the
11213 @xref{Service Types and Services}, for examples.
11216 @deffn {Scheme Procedure} service-extension @var{target-type} @
11218 Return a new extension for services of type @var{target-type}.
11219 @var{compute} must be a one-argument procedure: @code{fold-services}
11220 calls it, passing it the value associated with the service that provides
11221 the extension; it must return a valid value for the target service.
11224 @deffn {Scheme Procedure} service-extension? @var{obj}
11225 Return true if @var{obj} is a service extension.
11228 At the core of the service abstraction lies the @code{fold-services}
11229 procedure, which is responsible for ``compiling'' a list of services
11230 down to a single directory that contains everything needed to boot and
11231 run the system---the directory shown by the @command{guix system build}
11232 command (@pxref{Invoking guix system}). In essence, it propagates
11233 service extensions down the service graph, updating each node parameters
11234 on the way, until it reaches the root node.
11236 @deffn {Scheme Procedure} fold-services @var{services} @
11237 [#:target-type @var{system-service-type}]
11238 Fold @var{services} by propagating their extensions down to the root of
11239 type @var{target-type}; return the root service adjusted accordingly.
11242 Lastly, the @code{(gnu services)} module also defines several essential
11243 service types, some of which are listed below.
11245 @defvr {Scheme Variable} system-service-type
11246 This is the root of the service graph. It produces the system directory
11247 as returned by the @command{guix system build} command.
11250 @defvr {Scheme Variable} boot-service-type
11251 The type of the ``boot service'', which produces the @dfn{boot script}.
11252 The boot script is what the initial RAM disk runs when booting.
11255 @defvr {Scheme Variable} etc-service-type
11256 The type of the @file{/etc} service. This service can be extended by
11257 passing it name/file tuples such as:
11260 (list `("issue" ,(plain-file "issue" "Welcome!\n")))
11263 In this example, the effect would be to add an @file{/etc/issue} file
11264 pointing to the given file.
11267 @defvr {Scheme Variable} setuid-program-service-type
11268 Type for the ``setuid-program service''. This service collects lists of
11269 executable file names, passed as gexps, and adds them to the set of
11270 setuid-root programs on the system (@pxref{Setuid Programs}).
11273 @defvr {Scheme Variable} profile-service-type
11274 Type of the service that populates the @dfn{system profile}---i.e., the
11275 programs under @file{/run/current-system/profile}. Other services can
11276 extend it by passing it lists of packages to add to the system profile.
11280 @node Shepherd Services
11281 @subsubsection Shepherd Services
11284 @cindex init system
11285 The @code{(gnu services shepherd)} module provides a way to define
11286 services managed by the GNU@tie{}Shepherd, which is the GuixSD
11287 initialization system---the first process that is started when the
11288 system boots, also known as PID@tie{}1
11289 (@pxref{Introduction,,, shepherd, The GNU Shepherd Manual}).
11291 Services in the Shepherd can depend on each other. For instance, the
11292 SSH daemon may need to be started after the syslog daemon has been
11293 started, which in turn can only happen once all the file systems have
11294 been mounted. The simple operating system defined earlier (@pxref{Using
11295 the Configuration System}) results in a service graph like this:
11297 @image{images/shepherd-graph,,5in,Typical shepherd service graph.}
11299 You can actually generate such a graph for any operating system
11300 definition using the @command{guix system shepherd-graph} command
11301 (@pxref{system-shepherd-graph, @command{guix system shepherd-graph}}).
11303 The @var{%shepherd-root-service} is a service object representing
11304 PID@tie{}1, of type @var{shepherd-root-service-type}; it can be extended
11305 by passing it lists of @code{<shepherd-service>} objects.
11307 @deftp {Data Type} shepherd-service
11308 The data type representing a service managed by the Shepherd.
11311 @item @code{provision}
11312 This is a list of symbols denoting what the service provides.
11314 These are the names that may be passed to @command{herd start},
11315 @command{herd status}, and similar commands (@pxref{Invoking herd,,,
11316 shepherd, The GNU Shepherd Manual}). @xref{Slots of services, the
11317 @code{provides} slot,, shepherd, The GNU Shepherd Manual}, for details.
11319 @item @code{requirements} (default: @code{'()})
11320 List of symbols denoting the Shepherd services this one depends on.
11322 @item @code{respawn?} (default: @code{#t})
11323 Whether to restart the service when it stops, for instance when the
11324 underlying process dies.
11327 @itemx @code{stop} (default: @code{#~(const #f)})
11328 The @code{start} and @code{stop} fields refer to the Shepherd's
11329 facilities to start and stop processes (@pxref{Service De- and
11330 Constructors,,, shepherd, The GNU Shepherd Manual}). They are given as
11331 G-expressions that get expanded in the Shepherd configuration file
11332 (@pxref{G-Expressions}).
11334 @item @code{documentation}
11335 A documentation string, as shown when running:
11338 herd doc @var{service-name}
11341 where @var{service-name} is one of the symbols in @var{provision}
11342 (@pxref{Invoking herd,,, shepherd, The GNU Shepherd Manual}).
11344 @item @code{modules} (default: @var{%default-modules})
11345 This is the list of modules that must be in scope when @code{start} and
11346 @code{stop} are evaluated.
11351 @defvr {Scheme Variable} shepherd-root-service-type
11352 The service type for the Shepherd ``root service''---i.e., PID@tie{}1.
11354 This is the service type that extensions target when they want to create
11355 shepherd services (@pxref{Service Types and Services}, for an example).
11356 Each extension must pass a list of @code{<shepherd-service>}.
11359 @defvr {Scheme Variable} %shepherd-root-service
11360 This service represents PID@tie{}1.
11364 @node Installing Debugging Files
11365 @section Installing Debugging Files
11367 @cindex debugging files
11368 Program binaries, as produced by the GCC compilers for instance, are
11369 typically written in the ELF format, with a section containing
11370 @dfn{debugging information}. Debugging information is what allows the
11371 debugger, GDB, to map binary code to source code; it is required to
11372 debug a compiled program in good conditions.
11374 The problem with debugging information is that is takes up a fair amount
11375 of disk space. For example, debugging information for the GNU C Library
11376 weighs in at more than 60 MiB. Thus, as a user, keeping all the
11377 debugging info of all the installed programs is usually not an option.
11378 Yet, space savings should not come at the cost of an impediment to
11379 debugging---especially in the GNU system, which should make it easier
11380 for users to exert their computing freedom (@pxref{GNU Distribution}).
11382 Thankfully, the GNU Binary Utilities (Binutils) and GDB provide a
11383 mechanism that allows users to get the best of both worlds: debugging
11384 information can be stripped from the binaries and stored in separate
11385 files. GDB is then able to load debugging information from those files,
11386 when they are available (@pxref{Separate Debug Files,,, gdb, Debugging
11389 The GNU distribution takes advantage of this by storing debugging
11390 information in the @code{lib/debug} sub-directory of a separate package
11391 output unimaginatively called @code{debug} (@pxref{Packages with
11392 Multiple Outputs}). Users can choose to install the @code{debug} output
11393 of a package when they need it. For instance, the following command
11394 installs the debugging information for the GNU C Library and for GNU
11398 guix package -i glibc:debug guile:debug
11401 GDB must then be told to look for debug files in the user's profile, by
11402 setting the @code{debug-file-directory} variable (consider setting it
11403 from the @file{~/.gdbinit} file, @pxref{Startup,,, gdb, Debugging with
11407 (gdb) set debug-file-directory ~/.guix-profile/lib/debug
11410 From there on, GDB will pick up debugging information from the
11411 @code{.debug} files under @file{~/.guix-profile/lib/debug}.
11413 In addition, you will most likely want GDB to be able to show the source
11414 code being debugged. To do that, you will have to unpack the source
11415 code of the package of interest (obtained with @code{guix build
11416 --source}, @pxref{Invoking guix build}), and to point GDB to that source
11417 directory using the @code{directory} command (@pxref{Source Path,
11418 @code{directory},, gdb, Debugging with GDB}).
11420 @c XXX: keep me up-to-date
11421 The @code{debug} output mechanism in Guix is implemented by the
11422 @code{gnu-build-system} (@pxref{Build Systems}). Currently, it is
11423 opt-in---debugging information is available only for the packages
11424 with definitions explicitly declaring a @code{debug} output. This may be
11425 changed to opt-out in the future if our build farm servers can handle
11426 the load. To check whether a package has a @code{debug} output, use
11427 @command{guix package --list-available} (@pxref{Invoking guix package}).
11430 @node Security Updates
11431 @section Security Updates
11433 @cindex security updates
11434 @cindex security vulnerabilities
11435 Occasionally, important security vulnerabilities are discovered in software
11436 packages and must be patched. Guix developers try hard to keep track of
11437 known vulnerabilities and to apply fixes as soon as possible in the
11438 @code{master} branch of Guix (we do not yet provide a ``stable'' branch
11439 containing only security updates.) The @command{guix lint} tool helps
11440 developers find out about vulnerable versions of software packages in the
11445 gnu/packages/base.scm:652:2: glibc-2.21: probably vulnerable to CVE-2015-1781, CVE-2015-7547
11446 gnu/packages/gcc.scm:334:2: gcc-4.9.3: probably vulnerable to CVE-2015-5276
11447 gnu/packages/image.scm:312:2: openjpeg-2.1.0: probably vulnerable to CVE-2016-1923, CVE-2016-1924
11451 @xref{Invoking guix lint}, for more information.
11454 As of version @value{VERSION}, the feature described below is considered
11458 Guix follows a functional
11459 package management discipline (@pxref{Introduction}), which implies
11460 that, when a package is changed, @emph{every package that depends on it}
11461 must be rebuilt. This can significantly slow down the deployment of
11462 fixes in core packages such as libc or Bash, since basically the whole
11463 distribution would need to be rebuilt. Using pre-built binaries helps
11464 (@pxref{Substitutes}), but deployment may still take more time than
11468 To address this, Guix implements @dfn{grafts}, a mechanism that allows
11469 for fast deployment of critical updates without the costs associated
11470 with a whole-distribution rebuild. The idea is to rebuild only the
11471 package that needs to be patched, and then to ``graft'' it onto packages
11472 explicitly installed by the user and that were previously referring to
11473 the original package. The cost of grafting is typically very low, and
11474 order of magnitudes lower than a full rebuild of the dependency chain.
11476 @cindex replacements of packages, for grafts
11477 For instance, suppose a security update needs to be applied to Bash.
11478 Guix developers will provide a package definition for the ``fixed''
11479 Bash, say @var{bash-fixed}, in the usual way (@pxref{Defining
11480 Packages}). Then, the original package definition is augmented with a
11481 @code{replacement} field pointing to the package containing the bug fix:
11488 (replacement bash-fixed)))
11491 From there on, any package depending directly or indirectly on Bash---as
11492 reported by @command{guix gc --requisites} (@pxref{Invoking guix
11493 gc})---that is installed is automatically ``rewritten'' to refer to
11494 @var{bash-fixed} instead of @var{bash}. This grafting process takes
11495 time proportional to the size of the package, usually less than a
11496 minute for an ``average'' package on a recent machine. Grafting is
11497 recursive: when an indirect dependency requires grafting, then grafting
11498 ``propagates'' up to the package that the user is installing.
11500 Currently, the graft and the package it replaces (@var{bash-fixed} and
11501 @var{bash} in the example above) must have the exact same @code{name}
11502 and @code{version} fields. This restriction mostly comes from the fact
11503 that grafting works by patching files, including binary files, directly.
11504 Other restrictions may apply: for instance, when adding a graft to a
11505 package providing a shared library, the original shared library and its
11506 replacement must have the same @code{SONAME} and be binary-compatible.
11508 The @option{--no-grafts} command-line option allows you to forcefully
11509 avoid grafting (@pxref{Common Build Options, @option{--no-grafts}}).
11513 guix build bash --no-grafts
11517 returns the store file name of the original Bash, whereas:
11524 returns the store file name of the ``fixed'', replacement Bash. This
11525 allows you to distinguish between the two variants of Bash.
11527 To verify which Bash your whole profile refers to, you can run
11528 (@pxref{Invoking guix gc}):
11531 guix gc -R `readlink -f ~/.guix-profile` | grep bash
11535 @dots{} and compare the store file names that you get with those above.
11536 Likewise for a complete GuixSD system generation:
11539 guix gc -R `guix system build my-config.scm` | grep bash
11542 Lastly, to check which Bash running processes are using, you can use the
11543 @command{lsof} command:
11546 lsof | grep /gnu/store/.*bash
11550 @node Package Modules
11551 @section Package Modules
11553 From a programming viewpoint, the package definitions of the
11554 GNU distribution are provided by Guile modules in the @code{(gnu packages
11555 @dots{})} name space@footnote{Note that packages under the @code{(gnu
11556 packages @dots{})} module name space are not necessarily ``GNU
11557 packages''. This module naming scheme follows the usual Guile module
11558 naming convention: @code{gnu} means that these modules are distributed
11559 as part of the GNU system, and @code{packages} identifies modules that
11560 define packages.} (@pxref{Modules, Guile modules,, guile, GNU Guile
11561 Reference Manual}). For instance, the @code{(gnu packages emacs)}
11562 module exports a variable named @code{emacs}, which is bound to a
11563 @code{<package>} object (@pxref{Defining Packages}).
11565 The @code{(gnu packages @dots{})} module name space is
11566 automatically scanned for packages by the command-line tools. For
11567 instance, when running @code{guix package -i emacs}, all the @code{(gnu
11568 packages @dots{})} modules are scanned until one that exports a package
11569 object whose name is @code{emacs} is found. This package search
11570 facility is implemented in the @code{(gnu packages)} module.
11572 @cindex customization, of packages
11573 @cindex package module search path
11574 Users can store package definitions in modules with different
11575 names---e.g., @code{(my-packages emacs)}@footnote{Note that the file
11576 name and module name must match. For instance, the @code{(my-packages
11577 emacs)} module must be stored in a @file{my-packages/emacs.scm} file
11578 relative to the load path specified with @option{--load-path} or
11579 @code{GUIX_PACKAGE_PATH}. @xref{Modules and the File System,,,
11580 guile, GNU Guile Reference Manual}, for details.}. These package definitions
11581 will not be visible by default. Users can invoke commands such as
11582 @command{guix package} and @command{guix build} with the
11583 @code{-e} option so that they know where to find the package. Better
11584 yet, they can use the
11585 @code{-L} option of these commands to make those modules visible
11586 (@pxref{Invoking guix build, @code{--load-path}}), or define the
11587 @code{GUIX_PACKAGE_PATH} environment variable. This environment
11588 variable makes it easy to extend or customize the distribution and is
11589 honored by all the user interfaces.
11591 @defvr {Environment Variable} GUIX_PACKAGE_PATH
11592 This is a colon-separated list of directories to search for additional
11593 package modules. Directories listed in this variable take precedence
11594 over the own modules of the distribution.
11597 The distribution is fully @dfn{bootstrapped} and @dfn{self-contained}:
11598 each package is built based solely on other packages in the
11599 distribution. The root of this dependency graph is a small set of
11600 @dfn{bootstrap binaries}, provided by the @code{(gnu packages
11601 bootstrap)} module. For more information on bootstrapping,
11602 @pxref{Bootstrapping}.
11604 @node Packaging Guidelines
11605 @section Packaging Guidelines
11607 The GNU distribution is nascent and may well lack some of your favorite
11608 packages. This section describes how you can help make the distribution
11609 grow. @xref{Contributing}, for additional information on how you can
11612 Free software packages are usually distributed in the form of
11613 @dfn{source code tarballs}---typically @file{tar.gz} files that contain
11614 all the source files. Adding a package to the distribution means
11615 essentially two things: adding a @dfn{recipe} that describes how to
11616 build the package, including a list of other packages required to build
11617 it, and adding @dfn{package metadata} along with that recipe, such as a
11618 description and licensing information.
11620 In Guix all this information is embodied in @dfn{package definitions}.
11621 Package definitions provide a high-level view of the package. They are
11622 written using the syntax of the Scheme programming language; in fact,
11623 for each package we define a variable bound to the package definition,
11624 and export that variable from a module (@pxref{Package Modules}).
11625 However, in-depth Scheme knowledge is @emph{not} a prerequisite for
11626 creating packages. For more information on package definitions,
11627 @pxref{Defining Packages}.
11629 Once a package definition is in place, stored in a file in the Guix
11630 source tree, it can be tested using the @command{guix build} command
11631 (@pxref{Invoking guix build}). For example, assuming the new package is
11632 called @code{gnew}, you may run this command from the Guix build tree
11633 (@pxref{Running Guix Before It Is Installed}):
11636 ./pre-inst-env guix build gnew --keep-failed
11639 Using @code{--keep-failed} makes it easier to debug build failures since
11640 it provides access to the failed build tree. Another useful
11641 command-line option when debugging is @code{--log-file}, to access the
11644 If the package is unknown to the @command{guix} command, it may be that
11645 the source file contains a syntax error, or lacks a @code{define-public}
11646 clause to export the package variable. To figure it out, you may load
11647 the module from Guile to get more information about the actual error:
11650 ./pre-inst-env guile -c '(use-modules (gnu packages gnew))'
11653 Once your package builds correctly, please send us a patch
11654 (@pxref{Contributing}). Well, if you need help, we will be happy to
11655 help you too. Once the patch is committed in the Guix repository, the
11656 new package automatically gets built on the supported platforms by
11657 @url{http://hydra.gnu.org/jobset/gnu/master, our continuous integration
11660 @cindex substituter
11661 Users can obtain the new package definition simply by running
11662 @command{guix pull} (@pxref{Invoking guix pull}). When
11663 @code{hydra.gnu.org} is done building the package, installing the
11664 package automatically downloads binaries from there
11665 (@pxref{Substitutes}). The only place where human intervention is
11666 needed is to review and apply the patch.
11670 * Software Freedom:: What may go into the distribution.
11671 * Package Naming:: What's in a name?
11672 * Version Numbers:: When the name is not enough.
11673 * Synopses and Descriptions:: Helping users find the right package.
11674 * Python Modules:: Taming the snake.
11675 * Perl Modules:: Little pearls.
11676 * Java Packages:: Coffee break.
11677 * Fonts:: Fond of fonts.
11680 @node Software Freedom
11681 @subsection Software Freedom
11683 @c Adapted from http://www.gnu.org/philosophy/philosophy.html.
11685 The GNU operating system has been developed so that users can have
11686 freedom in their computing. GNU is @dfn{free software}, meaning that
11687 users have the @url{http://www.gnu.org/philosophy/free-sw.html,four
11688 essential freedoms}: to run the program, to study and change the program
11689 in source code form, to redistribute exact copies, and to distribute
11690 modified versions. Packages found in the GNU distribution provide only
11691 software that conveys these four freedoms.
11693 In addition, the GNU distribution follow the
11694 @url{http://www.gnu.org/distros/free-system-distribution-guidelines.html,free
11695 software distribution guidelines}. Among other things, these guidelines
11696 reject non-free firmware, recommendations of non-free software, and
11697 discuss ways to deal with trademarks and patents.
11699 Some otherwise free upstream package sources contain a small and optional
11700 subset that violates the above guidelines, for instance because this subset
11701 is itself non-free code. When that happens, the offending items are removed
11702 with appropriate patches or code snippets in the @code{origin} form of the
11703 package (@pxref{Defining Packages}). This way, @code{guix
11704 build --source} returns the ``freed'' source rather than the unmodified
11708 @node Package Naming
11709 @subsection Package Naming
11711 A package has actually two names associated with it:
11712 First, there is the name of the @emph{Scheme variable}, the one following
11713 @code{define-public}. By this name, the package can be made known in the
11714 Scheme code, for instance as input to another package. Second, there is
11715 the string in the @code{name} field of a package definition. This name
11716 is used by package management commands such as
11717 @command{guix package} and @command{guix build}.
11719 Both are usually the same and correspond to the lowercase conversion of
11720 the project name chosen upstream, with underscores replaced with
11721 hyphens. For instance, GNUnet is available as @code{gnunet}, and
11722 SDL_net as @code{sdl-net}.
11724 We do not add @code{lib} prefixes for library packages, unless these are
11725 already part of the official project name. But @pxref{Python
11726 Modules} and @ref{Perl Modules} for special rules concerning modules for
11727 the Python and Perl languages.
11729 Font package names are handled differently, @pxref{Fonts}.
11732 @node Version Numbers
11733 @subsection Version Numbers
11735 We usually package only the latest version of a given free software
11736 project. But sometimes, for instance for incompatible library versions,
11737 two (or more) versions of the same package are needed. These require
11738 different Scheme variable names. We use the name as defined
11739 in @ref{Package Naming}
11740 for the most recent version; previous versions use the same name, suffixed
11741 by @code{-} and the smallest prefix of the version number that may
11742 distinguish the two versions.
11744 The name inside the package definition is the same for all versions of a
11745 package and does not contain any version number.
11747 For instance, the versions 2.24.20 and 3.9.12 of GTK+ may be packaged as follows:
11750 (define-public gtk+
11755 (define-public gtk+-2
11758 (version "2.24.20")
11761 If we also wanted GTK+ 3.8.2, this would be packaged as
11763 (define-public gtk+-3.8
11770 @c See <https://lists.gnu.org/archive/html/guix-devel/2016-01/msg00425.html>,
11771 @c for a discussion of what follows.
11772 @cindex version number, for VCS snapshots
11773 Occasionally, we package snapshots of upstream's version control system
11774 (VCS) instead of formal releases. This should remain exceptional,
11775 because it is up to upstream developers to clarify what the stable
11776 release is. Yet, it is sometimes necessary. So, what should we put in
11777 the @code{version} field?
11779 Clearly, we need to make the commit identifier of the VCS snapshot
11780 visible in the version string, but we also need to make sure that the
11781 version string is monotonically increasing so that @command{guix package
11782 --upgrade} can determine which version is newer. Since commit
11783 identifiers, notably with Git, are not monotonically increasing, we add
11784 a revision number that we increase each time we upgrade to a newer
11785 snapshot. The resulting version string looks like this:
11790 | | `-- upstream commit ID
11792 | `--- Guix package revision
11794 latest upstream version
11797 It is a good idea to strip commit identifiers in the @code{version}
11798 field to, say, 7 digits. It avoids an aesthetic annoyance (assuming
11799 aesthetics have a role to play here) as well as problems related to OS
11800 limits such as the maximum shebang length (127 bytes for the Linux
11801 kernel.) It is best to use the full commit identifiers in
11802 @code{origin}s, though, to avoid ambiguities. A typical package
11803 definition may look like this:
11807 (let ((commit "c3f29bc928d5900971f65965feaae59e1272a3f7")
11808 (revision "1")) ;Guix package revision
11810 (version (string-append "0.9-" revision "."
11811 (string-take commit 7)))
11814 (uri (git-reference
11815 (url "git://example.org/my-package.git")
11817 (sha256 (base32 "1mbikn@dots{}"))
11818 (file-name (string-append "my-package-" version
11824 @node Synopses and Descriptions
11825 @subsection Synopses and Descriptions
11827 As we have seen before, each package in GNU@tie{}Guix includes a
11828 synopsis and a description (@pxref{Defining Packages}). Synopses and
11829 descriptions are important: They are what @command{guix package
11830 --search} searches, and a crucial piece of information to help users
11831 determine whether a given package suits their needs. Consequently,
11832 packagers should pay attention to what goes into them.
11834 Synopses must start with a capital letter and must not end with a
11835 period. They must not start with ``a'' or ``the'', which usually does
11836 not bring anything; for instance, prefer ``File-frobbing tool'' over ``A
11837 tool that frobs files''. The synopsis should say what the package
11838 is---e.g., ``Core GNU utilities (file, text, shell)''---or what it is
11839 used for---e.g., the synopsis for GNU@tie{}grep is ``Print lines
11840 matching a pattern''.
11842 Keep in mind that the synopsis must be meaningful for a very wide
11843 audience. For example, ``Manipulate alignments in the SAM format''
11844 might make sense for a seasoned bioinformatics researcher, but might be
11845 fairly unhelpful or even misleading to a non-specialized audience. It
11846 is a good idea to come up with a synopsis that gives an idea of the
11847 application domain of the package. In this example, this might give
11848 something like ``Manipulate nucleotide sequence alignments'', which
11849 hopefully gives the user a better idea of whether this is what they are
11852 Descriptions should take between five and ten lines. Use full
11853 sentences, and avoid using acronyms without first introducing them.
11854 Please avoid marketing phrases such as ``world-leading'',
11855 ``industrial-strength'', and ``next-generation'', and avoid superlatives
11856 like ``the most advanced''---they are not helpful to users looking for a
11857 package and may even sound suspicious. Instead, try to be factual,
11858 mentioning use cases and features.
11860 @cindex Texinfo markup, in package descriptions
11861 Descriptions can include Texinfo markup, which is useful to introduce
11862 ornaments such as @code{@@code} or @code{@@dfn}, bullet lists, or
11863 hyperlinks (@pxref{Overview,,, texinfo, GNU Texinfo}). However you
11864 should be careful when using some characters for example @samp{@@} and
11865 curly braces which are the basic special characters in Texinfo
11866 (@pxref{Special Characters,,, texinfo, GNU Texinfo}). User interfaces
11867 such as @command{guix package --show} take care of rendering it
11870 Synopses and descriptions are translated by volunteers
11871 @uref{http://translationproject.org/domain/guix-packages.html, at the
11872 Translation Project} so that as many users as possible can read them in
11873 their native language. User interfaces search them and display them in
11874 the language specified by the current locale.
11876 Translation is a lot of work so, as a packager, please pay even more
11877 attention to your synopses and descriptions as every change may entail
11878 additional work for translators. In order to help them, it is possible
11879 to make recommendations or instructions visible to them by inserting
11880 special comments like this (@pxref{xgettext Invocation,,, gettext, GNU
11884 ;; TRANSLATORS: "X11 resize-and-rotate" should not be translated.
11885 (description "ARandR is designed to provide a simple visual front end
11886 for the X11 resize-and-rotate (RandR) extension. @dots{}")
11890 @node Python Modules
11891 @subsection Python Modules
11893 We currently package Python 2 and Python 3, under the Scheme variable names
11894 @code{python-2} and @code{python} as explained in @ref{Version Numbers}.
11895 To avoid confusion and naming clashes with other programming languages, it
11896 seems desirable that the name of a package for a Python module contains
11897 the word @code{python}.
11899 Some modules are compatible with only one version of Python, others with both.
11900 If the package Foo compiles only with Python 3, we name it
11901 @code{python-foo}; if it compiles only with Python 2, we name it
11902 @code{python2-foo}. If it is compatible with both versions, we create two
11903 packages with the corresponding names.
11905 If a project already contains the word @code{python}, we drop this;
11906 for instance, the module python-dateutil is packaged under the names
11907 @code{python-dateutil} and @code{python2-dateutil}. If the project name
11908 starts with @code{py} (e.g. @code{pytz}), we keep it and prefix it as
11913 @subsection Perl Modules
11915 Perl programs standing for themselves are named as any other package,
11916 using the lowercase upstream name.
11917 For Perl packages containing a single class, we use the lowercase class name,
11918 replace all occurrences of @code{::} by dashes and prepend the prefix
11920 So the class @code{XML::Parser} becomes @code{perl-xml-parser}.
11921 Modules containing several classes keep their lowercase upstream name and
11922 are also prepended by @code{perl-}. Such modules tend to have the word
11923 @code{perl} somewhere in their name, which gets dropped in favor of the
11924 prefix. For instance, @code{libwww-perl} becomes @code{perl-libwww}.
11927 @node Java Packages
11928 @subsection Java Packages
11930 Java programs standing for themselves are named as any other package,
11931 using the lowercase upstream name.
11933 To avoid confusion and naming clashes with other programming languages,
11934 it is desirable that the name of a package for a Java package is
11935 prefixed with @code{java-}. If a project already contains the word
11936 @code{java}, we drop this; for instance, the package @code{ngsjava} is
11937 packaged under the name @code{java-ngs}.
11939 For Java packages containing a single class or a small class hierarchy,
11940 we use the lowercase class name, replace all occurrences of @code{.} by
11941 dashes and prepend the prefix @code{java-}. So the class
11942 @code{apache.commons.cli} becomes package
11943 @code{java-apache-commons-cli}.
11949 For fonts that are in general not installed by a user for typesetting
11950 purposes, or that are distributed as part of a larger software package,
11951 we rely on the general packaging rules for software; for instance, this
11952 applies to the fonts delivered as part of the X.Org system or fonts that
11953 are part of TeX Live.
11955 To make it easier for a user to search for fonts, names for other packages
11956 containing only fonts are constructed as follows, independently of the
11957 upstream package name.
11959 The name of a package containing only one font family starts with
11960 @code{font-}; it is followed by the foundry name and a dash @code{-}
11961 if the foundry is known, and the font family name, in which spaces are
11962 replaced by dashes (and as usual, all upper case letters are transformed
11964 For example, the Gentium font family by SIL is packaged under the name
11965 @code{font-sil-gentium}.
11967 For a package containing several font families, the name of the collection
11968 is used in the place of the font family name.
11969 For instance, the Liberation fonts consist of three families,
11970 Liberation Sans, Liberation Serif and Liberation Mono.
11971 These could be packaged separately under the names
11972 @code{font-liberation-sans} and so on; but as they are distributed together
11973 under a common name, we prefer to package them together as
11974 @code{font-liberation}.
11976 In the case where several formats of the same font family or font collection
11977 are packaged separately, a short form of the format, prepended by a dash,
11978 is added to the package name. We use @code{-ttf} for TrueType fonts,
11979 @code{-otf} for OpenType fonts and @code{-type1} for PostScript Type 1
11984 @node Bootstrapping
11985 @section Bootstrapping
11987 @c Adapted from the ELS 2013 paper.
11989 @cindex bootstrapping
11991 Bootstrapping in our context refers to how the distribution gets built
11992 ``from nothing''. Remember that the build environment of a derivation
11993 contains nothing but its declared inputs (@pxref{Introduction}). So
11994 there's an obvious chicken-and-egg problem: how does the first package
11995 get built? How does the first compiler get compiled? Note that this is
11996 a question of interest only to the curious hacker, not to the regular
11997 user, so you can shamelessly skip this section if you consider yourself
11998 a ``regular user''.
12000 @cindex bootstrap binaries
12001 The GNU system is primarily made of C code, with libc at its core. The
12002 GNU build system itself assumes the availability of a Bourne shell and
12003 command-line tools provided by GNU Coreutils, Awk, Findutils, `sed', and
12004 `grep'. Furthermore, build programs---programs that run
12005 @code{./configure}, @code{make}, etc.---are written in Guile Scheme
12006 (@pxref{Derivations}). Consequently, to be able to build anything at
12007 all, from scratch, Guix relies on pre-built binaries of Guile, GCC,
12008 Binutils, libc, and the other packages mentioned above---the
12009 @dfn{bootstrap binaries}.
12011 These bootstrap binaries are ``taken for granted'', though we can also
12012 re-create them if needed (more on that later).
12014 @unnumberedsubsec Preparing to Use the Bootstrap Binaries
12016 @c As of Emacs 24.3, Info-mode displays the image, but since it's a
12017 @c large image, it's hard to scroll. Oh well.
12018 @image{images/bootstrap-graph,6in,,Dependency graph of the early bootstrap derivations}
12020 The figure above shows the very beginning of the dependency graph of the
12021 distribution, corresponding to the package definitions of the @code{(gnu
12022 packages bootstrap)} module. A similar figure can be generated with
12023 @command{guix graph} (@pxref{Invoking guix graph}), along the lines of:
12026 guix graph -t derivation \
12027 -e '(@@@@ (gnu packages bootstrap) %bootstrap-gcc)' \
12031 At this level of detail, things are
12032 slightly complex. First, Guile itself consists of an ELF executable,
12033 along with many source and compiled Scheme files that are dynamically
12034 loaded when it runs. This gets stored in the @file{guile-2.0.7.tar.xz}
12035 tarball shown in this graph. This tarball is part of Guix's ``source''
12036 distribution, and gets inserted into the store with @code{add-to-store}
12037 (@pxref{The Store}).
12039 But how do we write a derivation that unpacks this tarball and adds it
12040 to the store? To solve this problem, the @code{guile-bootstrap-2.0.drv}
12041 derivation---the first one that gets built---uses @code{bash} as its
12042 builder, which runs @code{build-bootstrap-guile.sh}, which in turn calls
12043 @code{tar} to unpack the tarball. Thus, @file{bash}, @file{tar},
12044 @file{xz}, and @file{mkdir} are statically-linked binaries, also part of
12045 the Guix source distribution, whose sole purpose is to allow the Guile
12046 tarball to be unpacked.
12048 Once @code{guile-bootstrap-2.0.drv} is built, we have a functioning
12049 Guile that can be used to run subsequent build programs. Its first task
12050 is to download tarballs containing the other pre-built binaries---this
12051 is what the @code{.tar.xz.drv} derivations do. Guix modules such as
12052 @code{ftp-client.scm} are used for this purpose. The
12053 @code{module-import.drv} derivations import those modules in a directory
12054 in the store, using the original layout. The
12055 @code{module-import-compiled.drv} derivations compile those modules, and
12056 write them in an output directory with the right layout. This
12057 corresponds to the @code{#:modules} argument of
12058 @code{build-expression->derivation} (@pxref{Derivations}).
12060 Finally, the various tarballs are unpacked by the
12061 derivations @code{gcc-bootstrap-0.drv}, @code{glibc-bootstrap-0.drv},
12062 etc., at which point we have a working C tool chain.
12065 @unnumberedsubsec Building the Build Tools
12067 Bootstrapping is complete when we have a full tool chain that does not
12068 depend on the pre-built bootstrap tools discussed above. This
12069 no-dependency requirement is verified by checking whether the files of
12070 the final tool chain contain references to the @file{/gnu/store}
12071 directories of the bootstrap inputs. The process that leads to this
12072 ``final'' tool chain is described by the package definitions found in
12073 the @code{(gnu packages commencement)} module.
12075 The @command{guix graph} command allows us to ``zoom out'' compared to
12076 the graph above, by looking at the level of package objects instead of
12077 individual derivations---remember that a package may translate to
12078 several derivations, typically one derivation to download its source,
12079 one to build the Guile modules it needs, and one to actually build the
12080 package from source. The command:
12083 guix graph -t bag \
12084 -e '(@@@@ (gnu packages commencement)
12085 glibc-final-with-bootstrap-bash)' | dot -Tps > t.ps
12089 produces the dependency graph leading to the ``final'' C
12090 library@footnote{You may notice the @code{glibc-intermediate} label,
12091 suggesting that it is not @emph{quite} final, but as a good
12092 approximation, we will consider it final.}, depicted below.
12094 @image{images/bootstrap-packages,6in,,Dependency graph of the early packages}
12096 @c See <http://lists.gnu.org/archive/html/gnu-system-discuss/2012-10/msg00000.html>.
12097 The first tool that gets built with the bootstrap binaries is
12098 GNU@tie{}Make---noted @code{make-boot0} above---which is a prerequisite
12099 for all the following packages. From there Findutils and Diffutils get
12102 Then come the first-stage Binutils and GCC, built as pseudo cross
12103 tools---i.e., with @code{--target} equal to @code{--host}. They are
12104 used to build libc. Thanks to this cross-build trick, this libc is
12105 guaranteed not to hold any reference to the initial tool chain.
12107 From there the final Binutils and GCC (not shown above) are built.
12109 from the final Binutils, and links programs against the just-built libc.
12110 This tool chain is used to build the other packages used by Guix and by
12111 the GNU Build System: Guile, Bash, Coreutils, etc.
12113 And voilà! At this point we have the complete set of build tools that
12114 the GNU Build System expects. These are in the @code{%final-inputs}
12115 variable of the @code{(gnu packages commencement)} module, and are
12116 implicitly used by any package that uses @code{gnu-build-system}
12117 (@pxref{Build Systems, @code{gnu-build-system}}).
12120 @unnumberedsubsec Building the Bootstrap Binaries
12122 Because the final tool chain does not depend on the bootstrap binaries,
12123 those rarely need to be updated. Nevertheless, it is useful to have an
12124 automated way to produce them, should an update occur, and this is what
12125 the @code{(gnu packages make-bootstrap)} module provides.
12127 The following command builds the tarballs containing the bootstrap
12128 binaries (Guile, Binutils, GCC, libc, and a tarball containing a mixture
12129 of Coreutils and other basic command-line tools):
12132 guix build bootstrap-tarballs
12135 The generated tarballs are those that should be referred to in the
12136 @code{(gnu packages bootstrap)} module mentioned at the beginning of
12139 Still here? Then perhaps by now you've started to wonder: when do we
12140 reach a fixed point? That is an interesting question! The answer is
12141 unknown, but if you would like to investigate further (and have
12142 significant computational and storage resources to do so), then let us
12146 @section Porting to a New Platform
12148 As discussed above, the GNU distribution is self-contained, and
12149 self-containment is achieved by relying on pre-built ``bootstrap
12150 binaries'' (@pxref{Bootstrapping}). These binaries are specific to an
12151 operating system kernel, CPU architecture, and application binary
12152 interface (ABI). Thus, to port the distribution to a platform that is
12153 not yet supported, one must build those bootstrap binaries, and update
12154 the @code{(gnu packages bootstrap)} module to use them on that platform.
12156 Fortunately, Guix can @emph{cross compile} those bootstrap binaries.
12157 When everything goes well, and assuming the GNU tool chain supports the
12158 target platform, this can be as simple as running a command like this
12162 guix build --target=armv5tel-linux-gnueabi bootstrap-tarballs
12165 For this to work, the @code{glibc-dynamic-linker} procedure in
12166 @code{(gnu packages bootstrap)} must be augmented to return the right
12167 file name for libc's dynamic linker on that platform; likewise,
12168 @code{system->linux-architecture} in @code{(gnu packages linux)} must be
12169 taught about the new platform.
12171 Once these are built, the @code{(gnu packages bootstrap)} module needs
12172 to be updated to refer to these binaries on the target platform. That
12173 is, the hashes and URLs of the bootstrap tarballs for the new platform
12174 must be added alongside those of the currently supported platforms. The
12175 bootstrap Guile tarball is treated specially: it is expected to be
12176 available locally, and @file{gnu/local.mk} has rules do download it for
12177 the supported architectures; a rule for the new platform must be added
12180 In practice, there may be some complications. First, it may be that the
12181 extended GNU triplet that specifies an ABI (like the @code{eabi} suffix
12182 above) is not recognized by all the GNU tools. Typically, glibc
12183 recognizes some of these, whereas GCC uses an extra @code{--with-abi}
12184 configure flag (see @code{gcc.scm} for examples of how to handle this).
12185 Second, some of the required packages could fail to build for that
12186 platform. Lastly, the generated binaries could be broken for some
12189 @c *********************************************************************
12190 @include contributing.texi
12192 @c *********************************************************************
12193 @node Acknowledgments
12194 @chapter Acknowledgments
12196 Guix is based on the @uref{http://nixos.org/nix/, Nix package manager},
12197 which was designed and
12198 implemented by Eelco Dolstra, with contributions from other people (see
12199 the @file{nix/AUTHORS} file in Guix.) Nix pioneered functional package
12200 management, and promoted unprecedented features, such as transactional
12201 package upgrades and rollbacks, per-user profiles, and referentially
12202 transparent build processes. Without this work, Guix would not exist.
12204 The Nix-based software distributions, Nixpkgs and NixOS, have also been
12205 an inspiration for Guix.
12207 GNU@tie{}Guix itself is a collective work with contributions from a
12208 number of people. See the @file{AUTHORS} file in Guix for more
12209 information on these fine people. The @file{THANKS} file lists people
12210 who have helped by reporting bugs, taking care of the infrastructure,
12211 providing artwork and themes, making suggestions, and more---thank you!
12214 @c *********************************************************************
12215 @node GNU Free Documentation License
12216 @appendix GNU Free Documentation License
12218 @include fdl-1.3.texi
12220 @c *********************************************************************
12221 @node Concept Index
12222 @unnumbered Concept Index
12225 @node Programming Index
12226 @unnumbered Programming Index
12227 @syncodeindex tp fn
12228 @syncodeindex vr fn
12233 @c Local Variables:
12234 @c ispell-local-dictionary: "american";