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 envionment 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-3.3.5 | 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 computse 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}).
2578 * package Reference :: The package data type.
2579 * origin Reference:: The origin data type.
2583 @node package Reference
2584 @subsection @code{package} Reference
2586 This section summarizes all the options available in @code{package}
2587 declarations (@pxref{Defining Packages}).
2589 @deftp {Data Type} package
2590 This is the data type representing a package recipe.
2594 The name of the package, as a string.
2596 @item @code{version}
2597 The version of the package, as a string.
2600 An object telling how the source code for the package should be
2601 acquired. Most of the time, this is an @code{origin} object, which
2602 denotes a file fetched from the Internet (@pxref{origin Reference}). It
2603 can also be any other ``file-like'' object such as a @code{local-file},
2604 which denotes a file from the local file system (@pxref{G-Expressions,
2605 @code{local-file}}).
2607 @item @code{build-system}
2608 The build system that should be used to build the package (@pxref{Build
2611 @item @code{arguments} (default: @code{'()})
2612 The arguments that should be passed to the build system. This is a
2613 list, typically containing sequential keyword-value pairs.
2615 @item @code{inputs} (default: @code{'()})
2616 @itemx @code{native-inputs} (default: @code{'()})
2617 @itemx @code{propagated-inputs} (default: @code{'()})
2618 @cindex inputs, of packages
2619 These fields list dependencies of the package. Each one is a list of
2620 tuples, where each tuple has a label for the input (a string) as its
2621 first element, a package, origin, or derivation as its second element,
2622 and optionally the name of the output thereof that should be used, which
2623 defaults to @code{"out"} (@pxref{Packages with Multiple Outputs}, for
2624 more on package outputs). For example, the list below specifies three
2628 `(("libffi" ,libffi)
2629 ("libunistring" ,libunistring)
2630 ("glib:bin" ,glib "bin")) ;the "bin" output of Glib
2633 @cindex cross compilation, package dependencies
2634 The distinction between @code{native-inputs} and @code{inputs} is
2635 necessary when considering cross-compilation. When cross-compiling,
2636 dependencies listed in @code{inputs} are built for the @emph{target}
2637 architecture; conversely, dependencies listed in @code{native-inputs}
2638 are built for the architecture of the @emph{build} machine.
2640 @code{native-inputs} is typically used to list tools needed at
2641 build time, but not at run time, such as Autoconf, Automake, pkg-config,
2642 Gettext, or Bison. @command{guix lint} can report likely mistakes in
2643 this area (@pxref{Invoking guix lint}).
2645 @anchor{package-propagated-inputs}
2646 Lastly, @code{propagated-inputs} is similar to @code{inputs}, but the
2647 specified packages will be automatically installed alongside the package
2648 they belong to (@pxref{package-cmd-propagated-inputs, @command{guix
2649 package}}, for information on how @command{guix package} deals with
2652 For example this is necessary when a C/C++ library needs headers of
2653 another library to compile, or when a pkg-config file refers to another
2654 one @i{via} its @code{Requires} field.
2656 Another example where @code{propagated-inputs} is useful is for languages
2657 that lack a facility to record the run-time search path akin to the
2658 @code{RUNPATH} of ELF files; this includes Guile, Python, Perl, GHC, and
2659 more. To ensure that libraries written in those languages can find
2660 library code they depend on at run time, run-time dependencies must be
2661 listed in @code{propagated-inputs} rather than @code{inputs}.
2663 @item @code{self-native-input?} (default: @code{#f})
2664 This is a Boolean field telling whether the package should use itself as
2665 a native input when cross-compiling.
2667 @item @code{outputs} (default: @code{'("out")})
2668 The list of output names of the package. @xref{Packages with Multiple
2669 Outputs}, for typical uses of additional outputs.
2671 @item @code{native-search-paths} (default: @code{'()})
2672 @itemx @code{search-paths} (default: @code{'()})
2673 A list of @code{search-path-specification} objects describing
2674 search-path environment variables honored by the package.
2676 @item @code{replacement} (default: @code{#f})
2677 This must be either @code{#f} or a package object that will be used as a
2678 @dfn{replacement} for this package. @xref{Security Updates, grafts},
2681 @item @code{synopsis}
2682 A one-line description of the package.
2684 @item @code{description}
2685 A more elaborate description of the package.
2687 @item @code{license}
2688 The license of the package; a value from @code{(guix licenses)},
2689 or a list of such values.
2691 @item @code{home-page}
2692 The URL to the home-page of the package, as a string.
2694 @item @code{supported-systems} (default: @var{%supported-systems})
2695 The list of systems supported by the package, as strings of the form
2696 @code{architecture-kernel}, for example @code{"x86_64-linux"}.
2698 @item @code{maintainers} (default: @code{'()})
2699 The list of maintainers of the package, as @code{maintainer} objects.
2701 @item @code{location} (default: source location of the @code{package} form)
2702 The source location of the package. It is useful to override this when
2703 inheriting from another package, in which case this field is not
2704 automatically corrected.
2709 @node origin Reference
2710 @subsection @code{origin} Reference
2712 This section summarizes all the options available in @code{origin}
2713 declarations (@pxref{Defining Packages}).
2715 @deftp {Data Type} origin
2716 This is the data type representing a source code origin.
2720 An object containing the URI of the source. The object type depends on
2721 the @code{method} (see below). For example, when using the
2722 @var{url-fetch} method of @code{(guix download)}, the valid @code{uri}
2723 values are: a URL represented as a string, or a list thereof.
2726 A procedure that handles the URI.
2731 @item @var{url-fetch} from @code{(guix download)}
2732 download a file from the HTTP, HTTPS, or FTP URL specified in the
2736 @item @var{git-fetch} from @code{(guix git-download)}
2737 clone the Git version control repository, and check out the revision
2738 specified in the @code{uri} field as a @code{git-reference} object; a
2739 @code{git-reference} looks like this:
2743 (url "git://git.debian.org/git/pkg-shadow/shadow")
2744 (commit "v4.1.5.1"))
2749 A bytevector containing the SHA-256 hash of the source. Typically the
2750 @code{base32} form is used here to generate the bytevector from a
2753 You can obtain this information using @code{guix download}
2754 (@pxref{Invoking guix download}) or @code{guix hash} (@pxref{Invoking
2757 @item @code{file-name} (default: @code{#f})
2758 The file name under which the source code should be saved. When this is
2759 @code{#f}, a sensible default value will be used in most cases. In case
2760 the source is fetched from a URL, the file name from the URL will be
2761 used. For version control checkouts, it is recommended to provide the
2762 file name explicitly because the default is not very descriptive.
2764 @item @code{patches} (default: @code{'()})
2765 A list of file names containing patches to be applied to the source.
2767 @item @code{snippet} (default: @code{#f})
2768 A G-expression (@pxref{G-Expressions}) or S-expression that will be run
2769 in the source directory. This is a convenient way to modify the source,
2770 sometimes more convenient than a patch.
2772 @item @code{patch-flags} (default: @code{'("-p1")})
2773 A list of command-line flags that should be passed to the @code{patch}
2776 @item @code{patch-inputs} (default: @code{#f})
2777 Input packages or derivations to the patching process. When this is
2778 @code{#f}, the usual set of inputs necessary for patching are provided,
2779 such as GNU@tie{}Patch.
2781 @item @code{modules} (default: @code{'()})
2782 A list of Guile modules that should be loaded during the patching
2783 process and while running the code in the @code{snippet} field.
2785 @item @code{patch-guile} (default: @code{#f})
2786 The Guile package that should be used in the patching process. When
2787 this is @code{#f}, a sensible default is used.
2793 @section Build Systems
2795 @cindex build system
2796 Each package definition specifies a @dfn{build system} and arguments for
2797 that build system (@pxref{Defining Packages}). This @code{build-system}
2798 field represents the build procedure of the package, as well as implicit
2799 dependencies of that build procedure.
2801 Build systems are @code{<build-system>} objects. The interface to
2802 create and manipulate them is provided by the @code{(guix build-system)}
2803 module, and actual build systems are exported by specific modules.
2805 @cindex bag (low-level package representation)
2806 Under the hood, build systems first compile package objects to
2807 @dfn{bags}. A @dfn{bag} is like a package, but with less
2808 ornamentation---in other words, a bag is a lower-level representation of
2809 a package, which includes all the inputs of that package, including some
2810 that were implicitly added by the build system. This intermediate
2811 representation is then compiled to a derivation (@pxref{Derivations}).
2813 Build systems accept an optional list of @dfn{arguments}. In package
2814 definitions, these are passed @i{via} the @code{arguments} field
2815 (@pxref{Defining Packages}). They are typically keyword arguments
2816 (@pxref{Optional Arguments, keyword arguments in Guile,, guile, GNU
2817 Guile Reference Manual}). The value of these arguments is usually
2818 evaluated in the @dfn{build stratum}---i.e., by a Guile process launched
2819 by the daemon (@pxref{Derivations}).
2821 The main build system is @var{gnu-build-system}, which implements the
2822 standard build procedure for GNU and many other packages. It
2823 is provided by the @code{(guix build-system gnu)} module.
2825 @defvr {Scheme Variable} gnu-build-system
2826 @var{gnu-build-system} represents the GNU Build System, and variants
2827 thereof (@pxref{Configuration, configuration and makefile conventions,,
2828 standards, GNU Coding Standards}).
2830 @cindex build phases
2831 In a nutshell, packages using it are configured, built, and installed with
2832 the usual @code{./configure && make && make check && make install}
2833 command sequence. In practice, a few additional steps are often needed.
2834 All these steps are split up in separate @dfn{phases},
2835 notably@footnote{Please see the @code{(guix build gnu-build-system)}
2836 modules for more details about the build phases.}:
2840 Unpack the source tarball, and change the current directory to the
2841 extracted source tree. If the source is actually a directory, copy it
2842 to the build tree, and enter that directory.
2844 @item patch-source-shebangs
2845 Patch shebangs encountered in source files so they refer to the right
2846 store file names. For instance, this changes @code{#!/bin/sh} to
2847 @code{#!/gnu/store/@dots{}-bash-4.3/bin/sh}.
2850 Run the @file{configure} script with a number of default options, such
2851 as @code{--prefix=/gnu/store/@dots{}}, as well as the options specified
2852 by the @code{#:configure-flags} argument.
2855 Run @code{make} with the list of flags specified with
2856 @code{#:make-flags}. If the @code{#:parallel-build?} argument is true
2857 (the default), build with @code{make -j}.
2860 Run @code{make check}, or some other target specified with
2861 @code{#:test-target}, unless @code{#:tests? #f} is passed. If the
2862 @code{#:parallel-tests?} argument is true (the default), run @code{make
2866 Run @code{make install} with the flags listed in @code{#:make-flags}.
2868 @item patch-shebangs
2869 Patch shebangs on the installed executable files.
2872 Strip debugging symbols from ELF files (unless @code{#:strip-binaries?}
2873 is false), copying them to the @code{debug} output when available
2874 (@pxref{Installing Debugging Files}).
2877 @vindex %standard-phases
2878 The build-side module @code{(guix build gnu-build-system)} defines
2879 @var{%standard-phases} as the default list of build phases.
2880 @var{%standard-phases} is a list of symbol/procedure pairs, where the
2881 procedure implements the actual phase.
2883 The list of phases used for a particular package can be changed with the
2884 @code{#:phases} parameter. For instance, passing:
2887 #:phases (modify-phases %standard-phases (delete 'configure))
2890 means that all the phases described above will be used, except the
2891 @code{configure} phase.
2893 In addition, this build system ensures that the ``standard'' environment
2894 for GNU packages is available. This includes tools such as GCC, libc,
2895 Coreutils, Bash, Make, Diffutils, grep, and sed (see the @code{(guix
2896 build-system gnu)} module for a complete list). We call these the
2897 @dfn{implicit inputs} of a package, because package definitions do not
2898 have to mention them.
2901 Other @code{<build-system>} objects are defined to support other
2902 conventions and tools used by free software packages. They inherit most
2903 of @var{gnu-build-system}, and differ mainly in the set of inputs
2904 implicitly added to the build process, and in the list of phases
2905 executed. Some of these build systems are listed below.
2907 @defvr {Scheme Variable} ant-build-system
2908 This variable is exported by @code{(guix build-system ant)}. It
2909 implements the build procedure for Java packages that can be built with
2910 @url{http://ant.apache.org/, Ant build tool}.
2912 It adds both @code{ant} and the @dfn{Java Development Kit} (JDK) as
2913 provided by the @code{icedtea} package to the set of inputs. Different
2914 packages can be specified with the @code{#:ant} and @code{#:jdk}
2915 parameters, respectively.
2917 When the original package does not provide a suitable Ant build file,
2918 the parameter @code{#:jar-name} can be used to generate a minimal Ant
2919 build file @file{build.xml} with tasks to build the specified jar
2922 The parameter @code{#:build-target} can be used to specify the Ant task
2923 that should be run during the @code{build} phase. By default the
2924 ``jar'' task will be run.
2928 @defvr {Scheme Variable} cmake-build-system
2929 This variable is exported by @code{(guix build-system cmake)}. It
2930 implements the build procedure for packages using the
2931 @url{http://www.cmake.org, CMake build tool}.
2933 It automatically adds the @code{cmake} package to the set of inputs.
2934 Which package is used can be specified with the @code{#:cmake}
2937 The @code{#:configure-flags} parameter is taken as a list of flags
2938 passed to the @command{cmake} command. The @code{#:build-type}
2939 parameter specifies in abstract terms the flags passed to the compiler;
2940 it defaults to @code{"RelWithDebInfo"} (short for ``release mode with
2941 debugging information''), which roughly means that code is compiled with
2942 @code{-O2 -g}, as is the case for Autoconf-based packages by default.
2945 @defvr {Scheme Variable} glib-or-gtk-build-system
2946 This variable is exported by @code{(guix build-system glib-or-gtk)}. It
2947 is intended for use with packages making use of GLib or GTK+.
2949 This build system adds the following two phases to the ones defined by
2950 @var{gnu-build-system}:
2953 @item glib-or-gtk-wrap
2954 The phase @code{glib-or-gtk-wrap} ensures that programs in
2955 @file{bin/} are able to find GLib ``schemas'' and
2956 @uref{https://developer.gnome.org/gtk3/stable/gtk-running.html, GTK+
2957 modules}. This is achieved by wrapping the programs in launch scripts
2958 that appropriately set the @code{XDG_DATA_DIRS} and @code{GTK_PATH}
2959 environment variables.
2961 It is possible to exclude specific package outputs from that wrapping
2962 process by listing their names in the
2963 @code{#:glib-or-gtk-wrap-excluded-outputs} parameter. This is useful
2964 when an output is known not to contain any GLib or GTK+ binaries, and
2965 where wrapping would gratuitously add a dependency of that output on
2968 @item glib-or-gtk-compile-schemas
2969 The phase @code{glib-or-gtk-compile-schemas} makes sure that all
2970 @uref{https://developer.gnome.org/gio/stable/glib-compile-schemas.html,
2971 GSettings schemas} of GLib are compiled. Compilation is performed by the
2972 @command{glib-compile-schemas} program. It is provided by the package
2973 @code{glib:bin} which is automatically imported by the build system.
2974 The @code{glib} package providing @command{glib-compile-schemas} can be
2975 specified with the @code{#:glib} parameter.
2978 Both phases are executed after the @code{install} phase.
2981 @defvr {Scheme Variable} python-build-system
2982 This variable is exported by @code{(guix build-system python)}. It
2983 implements the more or less standard build procedure used by Python
2984 packages, which consists in running @code{python setup.py build} and
2985 then @code{python setup.py install --prefix=/gnu/store/@dots{}}.
2987 For packages that install stand-alone Python programs under @code{bin/},
2988 it takes care of wrapping these programs so that their @code{PYTHONPATH}
2989 environment variable points to all the Python libraries they depend on.
2991 Which Python package is used to perform the build can be specified with
2992 the @code{#:python} parameter. This is a useful way to force a package
2993 to be built for a specific version of the Python interpreter, which
2994 might be necessary if the package is only compatible with a single
2995 interpreter version.
2998 @defvr {Scheme Variable} perl-build-system
2999 This variable is exported by @code{(guix build-system perl)}. It
3000 implements the standard build procedure for Perl packages, which either
3001 consists in running @code{perl Build.PL --prefix=/gnu/store/@dots{}},
3002 followed by @code{Build} and @code{Build install}; or in running
3003 @code{perl Makefile.PL PREFIX=/gnu/store/@dots{}}, followed by
3004 @code{make} and @code{make install}, depending on which of
3005 @code{Build.PL} or @code{Makefile.PL} is present in the package
3006 distribution. Preference is given to the former if both @code{Build.PL}
3007 and @code{Makefile.PL} exist in the package distribution. This
3008 preference can be reversed by specifying @code{#t} for the
3009 @code{#:make-maker?} parameter.
3011 The initial @code{perl Makefile.PL} or @code{perl Build.PL} invocation
3012 passes flags specified by the @code{#:make-maker-flags} or
3013 @code{#:module-build-flags} parameter, respectively.
3015 Which Perl package is used can be specified with @code{#:perl}.
3018 @defvr {Scheme Variable} r-build-system
3019 This variable is exported by @code{(guix build-system r)}. It
3020 implements the build procedure used by @uref{http://r-project.org, R}
3021 packages, which essentially is little more than running @code{R CMD
3022 INSTALL --library=/gnu/store/@dots{}} in an environment where
3023 @code{R_LIBS_SITE} contains the paths to all R package inputs. Tests
3024 are run after installation using the R function
3025 @code{tools::testInstalledPackage}.
3028 @defvr {Scheme Variable} ruby-build-system
3029 This variable is exported by @code{(guix build-system ruby)}. It
3030 implements the RubyGems build procedure used by Ruby packages, which
3031 involves running @code{gem build} followed by @code{gem install}.
3033 The @code{source} field of a package that uses this build system
3034 typically references a gem archive, since this is the format that Ruby
3035 developers use when releasing their software. The build system unpacks
3036 the gem archive, potentially patches the source, runs the test suite,
3037 repackages the gem, and installs it. Additionally, directories and
3038 tarballs may be referenced to allow building unreleased gems from Git or
3039 a traditional source release tarball.
3041 Which Ruby package is used can be specified with the @code{#:ruby}
3042 parameter. A list of additional flags to be passed to the @command{gem}
3043 command can be specified with the @code{#:gem-flags} parameter.
3046 @defvr {Scheme Variable} waf-build-system
3047 This variable is exported by @code{(guix build-system waf)}. It
3048 implements a build procedure around the @code{waf} script. The common
3049 phases---@code{configure}, @code{build}, and @code{install}---are
3050 implemented by passing their names as arguments to the @code{waf}
3053 The @code{waf} script is executed by the Python interpreter. Which
3054 Python package is used to run the script can be specified with the
3055 @code{#:python} parameter.
3058 @defvr {Scheme Variable} haskell-build-system
3059 This variable is exported by @code{(guix build-system haskell)}. It
3060 implements the Cabal build procedure used by Haskell packages, which
3061 involves running @code{runhaskell Setup.hs configure
3062 --prefix=/gnu/store/@dots{}} and @code{runhaskell Setup.hs build}.
3063 Instead of installing the package by running @code{runhaskell Setup.hs
3064 install}, to avoid trying to register libraries in the read-only
3065 compiler store directory, the build system uses @code{runhaskell
3066 Setup.hs copy}, followed by @code{runhaskell Setup.hs register}. In
3067 addition, the build system generates the package documentation by
3068 running @code{runhaskell Setup.hs haddock}, unless @code{#:haddock? #f}
3069 is passed. Optional Haddock parameters can be passed with the help of
3070 the @code{#:haddock-flags} parameter. If the file @code{Setup.hs} is
3071 not found, the build system looks for @code{Setup.lhs} instead.
3073 Which Haskell compiler is used can be specified with the @code{#:haskell}
3074 parameter which defaults to @code{ghc}.
3077 @defvr {Scheme Variable} emacs-build-system
3078 This variable is exported by @code{(guix build-system emacs)}. It
3079 implements an installation procedure similar to the packaging system
3080 of Emacs itself (@pxref{Packages,,, emacs, The GNU Emacs Manual}).
3082 It first creates the @code{@var{package}-autoloads.el} file, then it
3083 byte compiles all Emacs Lisp files. Differently from the Emacs
3084 packaging system, the Info documentation files are moved to the standard
3085 documentation directory and the @file{dir} file is deleted. Each
3086 package is installed in its own directory under
3087 @file{share/emacs/site-lisp/guix.d}.
3090 Lastly, for packages that do not need anything as sophisticated, a
3091 ``trivial'' build system is provided. It is trivial in the sense that
3092 it provides basically no support: it does not pull any implicit inputs,
3093 and does not have a notion of build phases.
3095 @defvr {Scheme Variable} trivial-build-system
3096 This variable is exported by @code{(guix build-system trivial)}.
3098 This build system requires a @code{#:builder} argument. This argument
3099 must be a Scheme expression that builds the package output(s)---as
3100 with @code{build-expression->derivation} (@pxref{Derivations,
3101 @code{build-expression->derivation}}).
3111 Conceptually, the @dfn{store} is the place where derivations that have
3112 been built successfully are stored---by default, @file{/gnu/store}.
3113 Sub-directories in the store are referred to as @dfn{store items} or
3114 sometimes @dfn{store paths}. The store has an associated database that
3115 contains information such as the store paths referred to by each store
3116 path, and the list of @emph{valid} store items---results of successful
3117 builds. This database resides in @file{@var{localstatedir}/guix/db},
3118 where @var{localstatedir} is the state directory specified @i{via}
3119 @option{--localstatedir} at configure time, usually @file{/var}.
3121 The store is @emph{always} accessed by the daemon on behalf of its clients
3122 (@pxref{Invoking guix-daemon}). To manipulate the store, clients
3123 connect to the daemon over a Unix-domain socket, send requests to it,
3124 and read the result---these are remote procedure calls, or RPCs.
3127 Users must @emph{never} modify files under @file{/gnu/store} directly.
3128 This would lead to inconsistencies and break the immutability
3129 assumptions of Guix's functional model (@pxref{Introduction}).
3131 @xref{Invoking guix gc, @command{guix gc --verify}}, for information on
3132 how to check the integrity of the store and attempt recovery from
3133 accidental modifications.
3136 The @code{(guix store)} module provides procedures to connect to the
3137 daemon, and to perform RPCs. These are described below.
3139 @deffn {Scheme Procedure} open-connection [@var{file}] [#:reserve-space? #t]
3140 Connect to the daemon over the Unix-domain socket at @var{file}. When
3141 @var{reserve-space?} is true, instruct it to reserve a little bit of
3142 extra space on the file system so that the garbage collector can still
3143 operate should the disk become full. Return a server object.
3145 @var{file} defaults to @var{%default-socket-path}, which is the normal
3146 location given the options that were passed to @command{configure}.
3149 @deffn {Scheme Procedure} close-connection @var{server}
3150 Close the connection to @var{server}.
3153 @defvr {Scheme Variable} current-build-output-port
3154 This variable is bound to a SRFI-39 parameter, which refers to the port
3155 where build and error logs sent by the daemon should be written.
3158 Procedures that make RPCs all take a server object as their first
3161 @deffn {Scheme Procedure} valid-path? @var{server} @var{path}
3162 @cindex invalid store items
3163 Return @code{#t} when @var{path} designates a valid store item and
3164 @code{#f} otherwise (an invalid item may exist on disk but still be
3165 invalid, for instance because it is the result of an aborted or failed
3168 A @code{&nix-protocol-error} condition is raised if @var{path} is not
3169 prefixed by the store directory (@file{/gnu/store}).
3172 @deffn {Scheme Procedure} add-text-to-store @var{server} @var{name} @var{text} [@var{references}]
3173 Add @var{text} under file @var{name} in the store, and return its store
3174 path. @var{references} is the list of store paths referred to by the
3175 resulting store path.
3178 @deffn {Scheme Procedure} build-derivations @var{server} @var{derivations}
3179 Build @var{derivations} (a list of @code{<derivation>} objects or
3180 derivation paths), and return when the worker is done building them.
3181 Return @code{#t} on success.
3184 Note that the @code{(guix monads)} module provides a monad as well as
3185 monadic versions of the above procedures, with the goal of making it
3186 more convenient to work with code that accesses the store (@pxref{The
3190 @i{This section is currently incomplete.}
3193 @section Derivations
3196 Low-level build actions and the environment in which they are performed
3197 are represented by @dfn{derivations}. A derivation contains the
3198 following pieces of information:
3202 The outputs of the derivation---derivations produce at least one file or
3203 directory in the store, but may produce more.
3206 The inputs of the derivations, which may be other derivations or plain
3207 files in the store (patches, build scripts, etc.)
3210 The system type targeted by the derivation---e.g., @code{x86_64-linux}.
3213 The file name of a build script in the store, along with the arguments
3217 A list of environment variables to be defined.
3221 @cindex derivation path
3222 Derivations allow clients of the daemon to communicate build actions to
3223 the store. They exist in two forms: as an in-memory representation,
3224 both on the client- and daemon-side, and as files in the store whose
3225 name end in @code{.drv}---these files are referred to as @dfn{derivation
3226 paths}. Derivations paths can be passed to the @code{build-derivations}
3227 procedure to perform the build actions they prescribe (@pxref{The
3230 The @code{(guix derivations)} module provides a representation of
3231 derivations as Scheme objects, along with procedures to create and
3232 otherwise manipulate derivations. The lowest-level primitive to create
3233 a derivation is the @code{derivation} procedure:
3235 @deffn {Scheme Procedure} derivation @var{store} @var{name} @var{builder} @
3236 @var{args} [#:outputs '("out")] [#:hash #f] [#:hash-algo #f] @
3237 [#:recursive? #f] [#:inputs '()] [#:env-vars '()] @
3238 [#:system (%current-system)] [#:references-graphs #f] @
3239 [#:allowed-references #f] [#:disallowed-references #f] @
3240 [#:leaked-env-vars #f] [#:local-build? #f] @
3241 [#:substitutable? #t]
3242 Build a derivation with the given arguments, and return the resulting
3243 @code{<derivation>} object.
3245 When @var{hash} and @var{hash-algo} are given, a
3246 @dfn{fixed-output derivation} is created---i.e., one whose result is
3247 known in advance, such as a file download. If, in addition,
3248 @var{recursive?} is true, then that fixed output may be an executable
3249 file or a directory and @var{hash} must be the hash of an archive
3250 containing this output.
3252 When @var{references-graphs} is true, it must be a list of file
3253 name/store path pairs. In that case, the reference graph of each store
3254 path is exported in the build environment in the corresponding file, in
3255 a simple text format.
3257 When @var{allowed-references} is true, it must be a list of store items
3258 or outputs that the derivation's output may refer to. Likewise,
3259 @var{disallowed-references}, if true, must be a list of things the
3260 outputs may @emph{not} refer to.
3262 When @var{leaked-env-vars} is true, it must be a list of strings
3263 denoting environment variables that are allowed to ``leak'' from the
3264 daemon's environment to the build environment. This is only applicable
3265 to fixed-output derivations---i.e., when @var{hash} is true. The main
3266 use is to allow variables such as @code{http_proxy} to be passed to
3267 derivations that download files.
3269 When @var{local-build?} is true, declare that the derivation is not a
3270 good candidate for offloading and should rather be built locally
3271 (@pxref{Daemon Offload Setup}). This is the case for small derivations
3272 where the costs of data transfers would outweigh the benefits.
3274 When @var{substitutable?} is false, declare that substitutes of the
3275 derivation's output should not be used (@pxref{Substitutes}). This is
3276 useful, for instance, when building packages that capture details of the
3277 host CPU instruction set.
3281 Here's an example with a shell script as its builder, assuming
3282 @var{store} is an open connection to the daemon, and @var{bash} points
3283 to a Bash executable in the store:
3286 (use-modules (guix utils)
3290 (let ((builder ; add the Bash script to the store
3291 (add-text-to-store store "my-builder.sh"
3292 "echo hello world > $out\n" '())))
3293 (derivation store "foo"
3294 bash `("-e" ,builder)
3295 #:inputs `((,bash) (,builder))
3296 #:env-vars '(("HOME" . "/homeless"))))
3297 @result{} #<derivation /gnu/store/@dots{}-foo.drv => /gnu/store/@dots{}-foo>
3300 As can be guessed, this primitive is cumbersome to use directly. A
3301 better approach is to write build scripts in Scheme, of course! The
3302 best course of action for that is to write the build code as a
3303 ``G-expression'', and to pass it to @code{gexp->derivation}. For more
3304 information, @pxref{G-Expressions}.
3306 Once upon a time, @code{gexp->derivation} did not exist and constructing
3307 derivations with build code written in Scheme was achieved with
3308 @code{build-expression->derivation}, documented below. This procedure
3309 is now deprecated in favor of the much nicer @code{gexp->derivation}.
3311 @deffn {Scheme Procedure} build-expression->derivation @var{store} @
3312 @var{name} @var{exp} @
3313 [#:system (%current-system)] [#:inputs '()] @
3314 [#:outputs '("out")] [#:hash #f] [#:hash-algo #f] @
3315 [#:recursive? #f] [#:env-vars '()] [#:modules '()] @
3316 [#:references-graphs #f] [#:allowed-references #f] @
3317 [#:disallowed-references #f] @
3318 [#:local-build? #f] [#:substitutable? #t] [#:guile-for-build #f]
3319 Return a derivation that executes Scheme expression @var{exp} as a
3320 builder for derivation @var{name}. @var{inputs} must be a list of
3321 @code{(name drv-path sub-drv)} tuples; when @var{sub-drv} is omitted,
3322 @code{"out"} is assumed. @var{modules} is a list of names of Guile
3323 modules from the current search path to be copied in the store,
3324 compiled, and made available in the load path during the execution of
3325 @var{exp}---e.g., @code{((guix build utils) (guix build
3326 gnu-build-system))}.
3328 @var{exp} is evaluated in an environment where @code{%outputs} is bound
3329 to a list of output/path pairs, and where @code{%build-inputs} is bound
3330 to a list of string/output-path pairs made from @var{inputs}.
3331 Optionally, @var{env-vars} is a list of string pairs specifying the name
3332 and value of environment variables visible to the builder. The builder
3333 terminates by passing the result of @var{exp} to @code{exit}; thus, when
3334 @var{exp} returns @code{#f}, the build is considered to have failed.
3336 @var{exp} is built using @var{guile-for-build} (a derivation). When
3337 @var{guile-for-build} is omitted or is @code{#f}, the value of the
3338 @code{%guile-for-build} fluid is used instead.
3340 See the @code{derivation} procedure for the meaning of
3341 @var{references-graphs}, @var{allowed-references},
3342 @var{disallowed-references}, @var{local-build?}, and
3343 @var{substitutable?}.
3347 Here's an example of a single-output derivation that creates a directory
3348 containing one file:
3351 (let ((builder '(let ((out (assoc-ref %outputs "out")))
3352 (mkdir out) ; create /gnu/store/@dots{}-goo
3353 (call-with-output-file (string-append out "/test")
3355 (display '(hello guix) p))))))
3356 (build-expression->derivation store "goo" builder))
3358 @result{} #<derivation /gnu/store/@dots{}-goo.drv => @dots{}>
3362 @node The Store Monad
3363 @section The Store Monad
3367 The procedures that operate on the store described in the previous
3368 sections all take an open connection to the build daemon as their first
3369 argument. Although the underlying model is functional, they either have
3370 side effects or depend on the current state of the store.
3372 The former is inconvenient: the connection to the build daemon has to be
3373 carried around in all those functions, making it impossible to compose
3374 functions that do not take that parameter with functions that do. The
3375 latter can be problematic: since store operations have side effects
3376 and/or depend on external state, they have to be properly sequenced.
3378 @cindex monadic values
3379 @cindex monadic functions
3380 This is where the @code{(guix monads)} module comes in. This module
3381 provides a framework for working with @dfn{monads}, and a particularly
3382 useful monad for our uses, the @dfn{store monad}. Monads are a
3383 construct that allows two things: associating ``context'' with values
3384 (in our case, the context is the store), and building sequences of
3385 computations (here computations include accesses to the store). Values
3386 in a monad---values that carry this additional context---are called
3387 @dfn{monadic values}; procedures that return such values are called
3388 @dfn{monadic procedures}.
3390 Consider this ``normal'' procedure:
3393 (define (sh-symlink store)
3394 ;; Return a derivation that symlinks the 'bash' executable.
3395 (let* ((drv (package-derivation store bash))
3396 (out (derivation->output-path drv))
3397 (sh (string-append out "/bin/bash")))
3398 (build-expression->derivation store "sh"
3399 `(symlink ,sh %output))))
3402 Using @code{(guix monads)} and @code{(guix gexp)}, it may be rewritten
3403 as a monadic function:
3406 (define (sh-symlink)
3407 ;; Same, but return a monadic value.
3408 (mlet %store-monad ((drv (package->derivation bash)))
3409 (gexp->derivation "sh"
3410 #~(symlink (string-append #$drv "/bin/bash")
3414 There are several things to note in the second version: the @code{store}
3415 parameter is now implicit and is ``threaded'' in the calls to the
3416 @code{package->derivation} and @code{gexp->derivation} monadic
3417 procedures, and the monadic value returned by @code{package->derivation}
3418 is @dfn{bound} using @code{mlet} instead of plain @code{let}.
3420 As it turns out, the call to @code{package->derivation} can even be
3421 omitted since it will take place implicitly, as we will see later
3422 (@pxref{G-Expressions}):
3425 (define (sh-symlink)
3426 (gexp->derivation "sh"
3427 #~(symlink (string-append #$bash "/bin/bash")
3432 @c <https://syntaxexclamation.wordpress.com/2014/06/26/escaping-continuations/>
3433 @c for the funny quote.
3434 Calling the monadic @code{sh-symlink} has no effect. As someone once
3435 said, ``you exit a monad like you exit a building on fire: by running''.
3436 So, to exit the monad and get the desired effect, one must use
3437 @code{run-with-store}:
3440 (run-with-store (open-connection) (sh-symlink))
3441 @result{} /gnu/store/...-sh-symlink
3444 Note that the @code{(guix monad-repl)} module extends the Guile REPL with
3445 new ``meta-commands'' to make it easier to deal with monadic procedures:
3446 @code{run-in-store}, and @code{enter-store-monad}. The former is used
3447 to ``run'' a single monadic value through the store:
3450 scheme@@(guile-user)> ,run-in-store (package->derivation hello)
3451 $1 = #<derivation /gnu/store/@dots{}-hello-2.9.drv => @dots{}>
3454 The latter enters a recursive REPL, where all the return values are
3455 automatically run through the store:
3458 scheme@@(guile-user)> ,enter-store-monad
3459 store-monad@@(guile-user) [1]> (package->derivation hello)
3460 $2 = #<derivation /gnu/store/@dots{}-hello-2.9.drv => @dots{}>
3461 store-monad@@(guile-user) [1]> (text-file "foo" "Hello!")
3462 $3 = "/gnu/store/@dots{}-foo"
3463 store-monad@@(guile-user) [1]> ,q
3464 scheme@@(guile-user)>
3468 Note that non-monadic values cannot be returned in the
3469 @code{store-monad} REPL.
3471 The main syntactic forms to deal with monads in general are provided by
3472 the @code{(guix monads)} module and are described below.
3474 @deffn {Scheme Syntax} with-monad @var{monad} @var{body} ...
3475 Evaluate any @code{>>=} or @code{return} forms in @var{body} as being
3479 @deffn {Scheme Syntax} return @var{val}
3480 Return a monadic value that encapsulates @var{val}.
3483 @deffn {Scheme Syntax} >>= @var{mval} @var{mproc} ...
3484 @dfn{Bind} monadic value @var{mval}, passing its ``contents'' to monadic
3485 procedures @var{mproc}@dots{}@footnote{This operation is commonly
3486 referred to as ``bind'', but that name denotes an unrelated procedure in
3487 Guile. Thus we use this somewhat cryptic symbol inherited from the
3488 Haskell language.}. There can be one @var{mproc} or several of them, as
3493 (with-monad %state-monad
3495 (lambda (x) (return (+ 1 x)))
3496 (lambda (x) (return (* 2 x)))))
3500 @result{} some-state
3504 @deffn {Scheme Syntax} mlet @var{monad} ((@var{var} @var{mval}) ...) @
3506 @deffnx {Scheme Syntax} mlet* @var{monad} ((@var{var} @var{mval}) ...) @
3508 Bind the variables @var{var} to the monadic values @var{mval} in
3509 @var{body}. The form (@var{var} -> @var{val}) binds @var{var} to the
3510 ``normal'' value @var{val}, as per @code{let}.
3512 @code{mlet*} is to @code{mlet} what @code{let*} is to @code{let}
3513 (@pxref{Local Bindings,,, guile, GNU Guile Reference Manual}).
3516 @deffn {Scheme System} mbegin @var{monad} @var{mexp} ...
3517 Bind @var{mexp} and the following monadic expressions in sequence,
3518 returning the result of the last expression.
3520 This is akin to @code{mlet}, except that the return values of the
3521 monadic expressions are ignored. In that sense, it is analogous to
3522 @code{begin}, but applied to monadic expressions.
3526 The @code{(guix monads)} module provides the @dfn{state monad}, which
3527 allows an additional value---the state---to be @emph{threaded} through
3528 monadic procedure calls.
3530 @defvr {Scheme Variable} %state-monad
3531 The state monad. Procedures in the state monad can access and change
3532 the state that is threaded.
3534 Consider the example below. The @code{square} procedure returns a value
3535 in the state monad. It returns the square of its argument, but also
3536 increments the current state value:
3540 (mlet %state-monad ((count (current-state)))
3541 (mbegin %state-monad
3542 (set-current-state (+ 1 count))
3545 (run-with-state (sequence %state-monad (map square (iota 3))) 0)
3550 When ``run'' through @var{%state-monad}, we obtain that additional state
3551 value, which is the number of @code{square} calls.
3554 @deffn {Monadic Procedure} current-state
3555 Return the current state as a monadic value.
3558 @deffn {Monadic Procedure} set-current-state @var{value}
3559 Set the current state to @var{value} and return the previous state as a
3563 @deffn {Monadic Procedure} state-push @var{value}
3564 Push @var{value} to the current state, which is assumed to be a list,
3565 and return the previous state as a monadic value.
3568 @deffn {Monadic Procedure} state-pop
3569 Pop a value from the current state and return it as a monadic value.
3570 The state is assumed to be a list.
3573 @deffn {Scheme Procedure} run-with-state @var{mval} [@var{state}]
3574 Run monadic value @var{mval} starting with @var{state} as the initial
3575 state. Return two values: the resulting value, and the resulting state.
3578 The main interface to the store monad, provided by the @code{(guix
3579 store)} module, is as follows.
3581 @defvr {Scheme Variable} %store-monad
3582 The store monad---an alias for @var{%state-monad}.
3584 Values in the store monad encapsulate accesses to the store. When its
3585 effect is needed, a value of the store monad must be ``evaluated'' by
3586 passing it to the @code{run-with-store} procedure (see below.)
3589 @deffn {Scheme Procedure} run-with-store @var{store} @var{mval} [#:guile-for-build] [#:system (%current-system)]
3590 Run @var{mval}, a monadic value in the store monad, in @var{store}, an
3591 open store connection.
3594 @deffn {Monadic Procedure} text-file @var{name} @var{text} [@var{references}]
3595 Return as a monadic value the absolute file name in the store of the file
3596 containing @var{text}, a string. @var{references} is a list of store items that the
3597 resulting text file refers to; it defaults to the empty list.
3600 @deffn {Monadic Procedure} interned-file @var{file} [@var{name}] @
3601 [#:recursive? #t] [#:select? (const #t)]
3602 Return the name of @var{file} once interned in the store. Use
3603 @var{name} as its store name, or the basename of @var{file} if
3604 @var{name} is omitted.
3606 When @var{recursive?} is true, the contents of @var{file} are added
3607 recursively; if @var{file} designates a flat file and @var{recursive?}
3608 is true, its contents are added, and its permission bits are kept.
3610 When @var{recursive?} is true, call @code{(@var{select?} @var{file}
3611 @var{stat})} for each directory entry, where @var{file} is the entry's
3612 absolute file name and @var{stat} is the result of @code{lstat}; exclude
3613 entries for which @var{select?} does not return true.
3615 The example below adds a file to the store, under two different names:
3618 (run-with-store (open-connection)
3619 (mlet %store-monad ((a (interned-file "README"))
3620 (b (interned-file "README" "LEGU-MIN")))
3621 (return (list a b))))
3623 @result{} ("/gnu/store/rwm@dots{}-README" "/gnu/store/44i@dots{}-LEGU-MIN")
3628 The @code{(guix packages)} module exports the following package-related
3631 @deffn {Monadic Procedure} package-file @var{package} [@var{file}] @
3632 [#:system (%current-system)] [#:target #f] @
3635 value in the absolute file name of @var{file} within the @var{output}
3636 directory of @var{package}. When @var{file} is omitted, return the name
3637 of the @var{output} directory of @var{package}. When @var{target} is
3638 true, use it as a cross-compilation target triplet.
3641 @deffn {Monadic Procedure} package->derivation @var{package} [@var{system}]
3642 @deffnx {Monadic Procedure} package->cross-derivation @var{package} @
3643 @var{target} [@var{system}]
3644 Monadic version of @code{package-derivation} and
3645 @code{package-cross-derivation} (@pxref{Defining Packages}).
3650 @section G-Expressions
3652 @cindex G-expression
3653 @cindex build code quoting
3654 So we have ``derivations'', which represent a sequence of build actions
3655 to be performed to produce an item in the store (@pxref{Derivations}).
3656 These build actions are performed when asking the daemon to actually
3657 build the derivations; they are run by the daemon in a container
3658 (@pxref{Invoking guix-daemon}).
3660 @cindex strata of code
3661 It should come as no surprise that we like to write these build actions
3662 in Scheme. When we do that, we end up with two @dfn{strata} of Scheme
3663 code@footnote{The term @dfn{stratum} in this context was coined by
3664 Manuel Serrano et al.@: in the context of their work on Hop. Oleg
3665 Kiselyov, who has written insightful
3666 @url{http://okmij.org/ftp/meta-programming/#meta-scheme, essays and code
3667 on this topic}, refers to this kind of code generation as
3668 @dfn{staging}.}: the ``host code''---code that defines packages, talks
3669 to the daemon, etc.---and the ``build code''---code that actually
3670 performs build actions, such as making directories, invoking
3671 @command{make}, etc.
3673 To describe a derivation and its build actions, one typically needs to
3674 embed build code inside host code. It boils down to manipulating build
3675 code as data, and the homoiconicity of Scheme---code has a direct
3676 representation as data---comes in handy for that. But we need more than
3677 the normal @code{quasiquote} mechanism in Scheme to construct build
3680 The @code{(guix gexp)} module implements @dfn{G-expressions}, a form of
3681 S-expressions adapted to build expressions. G-expressions, or
3682 @dfn{gexps}, consist essentially of three syntactic forms: @code{gexp},
3683 @code{ungexp}, and @code{ungexp-splicing} (or simply: @code{#~},
3684 @code{#$}, and @code{#$@@}), which are comparable to
3685 @code{quasiquote}, @code{unquote}, and @code{unquote-splicing},
3686 respectively (@pxref{Expression Syntax, @code{quasiquote},, guile,
3687 GNU Guile Reference Manual}). However, there are major differences:
3691 Gexps are meant to be written to a file and run or manipulated by other
3695 When a high-level object such as a package or derivation is unquoted
3696 inside a gexp, the result is as if its output file name had been
3700 Gexps carry information about the packages or derivations they refer to,
3701 and these dependencies are automatically added as inputs to the build
3702 processes that use them.
3705 @cindex lowering, of high-level objects in gexps
3706 This mechanism is not limited to package and derivation
3707 objects: @dfn{compilers} able to ``lower'' other high-level objects to
3708 derivations or files in the store can be defined,
3709 such that these objects can also be inserted
3710 into gexps. For example, a useful type of high-level objects that can be
3711 inserted in a gexp is ``file-like objects'', which make it easy to
3712 add files to the store and to refer to them in
3713 derivations and such (see @code{local-file} and @code{plain-file}
3716 To illustrate the idea, here is an example of a gexp:
3723 (symlink (string-append #$coreutils "/bin/ls")
3727 This gexp can be passed to @code{gexp->derivation}; we obtain a
3728 derivation that builds a directory containing exactly one symlink to
3729 @file{/gnu/store/@dots{}-coreutils-8.22/bin/ls}:
3732 (gexp->derivation "the-thing" build-exp)
3735 As one would expect, the @code{"/gnu/store/@dots{}-coreutils-8.22"} string is
3736 substituted to the reference to the @var{coreutils} package in the
3737 actual build code, and @var{coreutils} is automatically made an input to
3738 the derivation. Likewise, @code{#$output} (equivalent to @code{(ungexp
3739 output)}) is replaced by a string containing the directory name of the
3740 output of the derivation.
3742 @cindex cross compilation
3743 In a cross-compilation context, it is useful to distinguish between
3744 references to the @emph{native} build of a package---that can run on the
3745 host---versus references to cross builds of a package. To that end, the
3746 @code{#+} plays the same role as @code{#$}, but is a reference to a
3747 native package build:
3750 (gexp->derivation "vi"
3753 (system* (string-append #+coreutils "/bin/ln")
3755 (string-append #$emacs "/bin/emacs")
3756 (string-append #$output "/bin/vi")))
3757 #:target "mips64el-linux")
3761 In the example above, the native build of @var{coreutils} is used, so
3762 that @command{ln} can actually run on the host; but then the
3763 cross-compiled build of @var{emacs} is referenced.
3765 @cindex imported modules, for gexps
3766 @findex with-imported-modules
3767 Another gexp feature is @dfn{imported modules}: sometimes you want to be
3768 able to use certain Guile modules from the ``host environment'' in the
3769 gexp, so those modules should be imported in the ``build environment''.
3770 The @code{with-imported-modules} form allows you to express that:
3773 (let ((build (with-imported-modules '((guix build utils))
3775 (use-modules (guix build utils))
3776 (mkdir-p (string-append #$output "/bin"))))))
3777 (gexp->derivation "empty-dir"
3780 (display "success!\n")
3785 In this example, the @code{(guix build utils)} module is automatically
3786 pulled into the isolated build environment of our gexp, such that
3787 @code{(use-modules (guix build utils))} works as expected.
3789 The syntactic form to construct gexps is summarized below.
3791 @deffn {Scheme Syntax} #~@var{exp}
3792 @deffnx {Scheme Syntax} (gexp @var{exp})
3793 Return a G-expression containing @var{exp}. @var{exp} may contain one
3794 or more of the following forms:
3798 @itemx (ungexp @var{obj})
3799 Introduce a reference to @var{obj}. @var{obj} may have one of the
3800 supported types, for example a package or a
3801 derivation, in which case the @code{ungexp} form is replaced by its
3802 output file name---e.g., @code{"/gnu/store/@dots{}-coreutils-8.22}.
3804 If @var{obj} is a list, it is traversed and references to supported
3805 objects are substituted similarly.
3807 If @var{obj} is another gexp, its contents are inserted and its
3808 dependencies are added to those of the containing gexp.
3810 If @var{obj} is another kind of object, it is inserted as is.
3812 @item #$@var{obj}:@var{output}
3813 @itemx (ungexp @var{obj} @var{output})
3814 This is like the form above, but referring explicitly to the
3815 @var{output} of @var{obj}---this is useful when @var{obj} produces
3816 multiple outputs (@pxref{Packages with Multiple Outputs}).
3819 @itemx #+@var{obj}:output
3820 @itemx (ungexp-native @var{obj})
3821 @itemx (ungexp-native @var{obj} @var{output})
3822 Same as @code{ungexp}, but produces a reference to the @emph{native}
3823 build of @var{obj} when used in a cross compilation context.
3825 @item #$output[:@var{output}]
3826 @itemx (ungexp output [@var{output}])
3827 Insert a reference to derivation output @var{output}, or to the main
3828 output when @var{output} is omitted.
3830 This only makes sense for gexps passed to @code{gexp->derivation}.
3833 @itemx (ungexp-splicing @var{lst})
3834 Like the above, but splices the contents of @var{lst} inside the
3838 @itemx (ungexp-native-splicing @var{lst})
3839 Like the above, but refers to native builds of the objects listed in
3844 G-expressions created by @code{gexp} or @code{#~} are run-time objects
3845 of the @code{gexp?} type (see below.)
3848 @deffn {Scheme Syntax} with-imported-modules @var{modules} @var{body}@dots{}
3849 Mark the gexps defined in @var{body}@dots{} as requiring @var{modules}
3850 in their execution environment. @var{modules} must be a list of Guile
3851 module names, such as @code{'((guix build utils) (guix build gremlin))}.
3853 This form has @emph{lexical} scope: it has an effect on the gexps
3854 directly defined in @var{body}@dots{}, but not on those defined, say, in
3855 procedures called from @var{body}@dots{}.
3858 @deffn {Scheme Procedure} gexp? @var{obj}
3859 Return @code{#t} if @var{obj} is a G-expression.
3862 G-expressions are meant to be written to disk, either as code building
3863 some derivation, or as plain files in the store. The monadic procedures
3864 below allow you to do that (@pxref{The Store Monad}, for more
3865 information about monads.)
3867 @deffn {Monadic Procedure} gexp->derivation @var{name} @var{exp} @
3868 [#:system (%current-system)] [#:target #f] [#:graft? #t] @
3869 [#:hash #f] [#:hash-algo #f] @
3870 [#:recursive? #f] [#:env-vars '()] [#:modules '()] @
3871 [#:module-path @var{%load-path}] @
3872 [#:references-graphs #f] [#:allowed-references #f] @
3873 [#:disallowed-references #f] @
3874 [#:leaked-env-vars #f] @
3875 [#:script-name (string-append @var{name} "-builder")] @
3876 [#:local-build? #f] [#:substitutable? #t] [#:guile-for-build #f]
3877 Return a derivation @var{name} that runs @var{exp} (a gexp) with
3878 @var{guile-for-build} (a derivation) on @var{system}; @var{exp} is
3879 stored in a file called @var{script-name}. When @var{target} is true,
3880 it is used as the cross-compilation target triplet for packages referred
3883 @var{modules} is deprecated in favor of @code{with-imported-modules}.
3885 make @var{modules} available in the evaluation context of @var{exp};
3886 @var{modules} is a list of names of Guile modules searched in
3887 @var{module-path} to be copied in the store, compiled, and made available in
3888 the load path during the execution of @var{exp}---e.g., @code{((guix
3889 build utils) (guix build gnu-build-system))}.
3891 @var{graft?} determines whether packages referred to by @var{exp} should be grafted when
3894 When @var{references-graphs} is true, it must be a list of tuples of one of the
3898 (@var{file-name} @var{package})
3899 (@var{file-name} @var{package} @var{output})
3900 (@var{file-name} @var{derivation})
3901 (@var{file-name} @var{derivation} @var{output})
3902 (@var{file-name} @var{store-item})
3905 The right-hand-side of each element of @var{references-graphs} is automatically made
3906 an input of the build process of @var{exp}. In the build environment, each
3907 @var{file-name} contains the reference graph of the corresponding item, in a simple
3910 @var{allowed-references} must be either @code{#f} or a list of output names and packages.
3911 In the latter case, the list denotes store items that the result is allowed to
3912 refer to. Any reference to another store item will lead to a build error.
3913 Similarly for @var{disallowed-references}, which can list items that must not be
3914 referenced by the outputs.
3916 The other arguments are as for @code{derivation} (@pxref{Derivations}).
3919 @cindex file-like objects
3920 The @code{local-file}, @code{plain-file}, @code{computed-file},
3921 @code{program-file}, and @code{scheme-file} procedures below return
3922 @dfn{file-like objects}. That is, when unquoted in a G-expression,
3923 these objects lead to a file in the store. Consider this G-expression:
3926 #~(system* (string-append #$glibc "/sbin/nscd") "-f"
3927 #$(local-file "/tmp/my-nscd.conf"))
3930 The effect here is to ``intern'' @file{/tmp/my-nscd.conf} by copying it
3931 to the store. Once expanded, for instance @i{via}
3932 @code{gexp->derivation}, the G-expression refers to that copy under
3933 @file{/gnu/store}; thus, modifying or removing the file in @file{/tmp}
3934 does not have any effect on what the G-expression does.
3935 @code{plain-file} can be used similarly; it differs in that the file
3936 content is directly passed as a string.
3938 @deffn {Scheme Procedure} local-file @var{file} [@var{name}] @
3939 [#:recursive? #f] [#:select? (const #t)]
3940 Return an object representing local file @var{file} to add to the store; this
3941 object can be used in a gexp. If @var{file} is a relative file name, it is looked
3942 up relative to the source file where this form appears. @var{file} will be added to
3943 the store under @var{name}--by default the base name of @var{file}.
3945 When @var{recursive?} is true, the contents of @var{file} are added recursively; if @var{file}
3946 designates a flat file and @var{recursive?} is true, its contents are added, and its
3947 permission bits are kept.
3949 When @var{recursive?} is true, call @code{(@var{select?} @var{file}
3950 @var{stat})} for each directory entry, where @var{file} is the entry's
3951 absolute file name and @var{stat} is the result of @code{lstat}; exclude
3952 entries for which @var{select?} does not return true.
3954 This is the declarative counterpart of the @code{interned-file} monadic
3955 procedure (@pxref{The Store Monad, @code{interned-file}}).
3958 @deffn {Scheme Procedure} plain-file @var{name} @var{content}
3959 Return an object representing a text file called @var{name} with the given
3960 @var{content} (a string) to be added to the store.
3962 This is the declarative counterpart of @code{text-file}.
3965 @deffn {Scheme Procedure} computed-file @var{name} @var{gexp} @
3966 [#:options '(#:local-build? #t)]
3967 Return an object representing the store item @var{name}, a file or
3968 directory computed by @var{gexp}. @var{options}
3969 is a list of additional arguments to pass to @code{gexp->derivation}.
3971 This is the declarative counterpart of @code{gexp->derivation}.
3974 @deffn {Monadic Procedure} gexp->script @var{name} @var{exp}
3975 Return an executable script @var{name} that runs @var{exp} using
3976 @var{guile}, with @var{exp}'s imported modules in its search path.
3978 The example below builds a script that simply invokes the @command{ls}
3982 (use-modules (guix gexp) (gnu packages base))
3984 (gexp->script "list-files"
3985 #~(execl (string-append #$coreutils "/bin/ls")
3989 When ``running'' it through the store (@pxref{The Store Monad,
3990 @code{run-with-store}}), we obtain a derivation that produces an
3991 executable file @file{/gnu/store/@dots{}-list-files} along these lines:
3994 #!/gnu/store/@dots{}-guile-2.0.11/bin/guile -ds
3996 (execl (string-append "/gnu/store/@dots{}-coreutils-8.22"/bin/ls")
4001 @deffn {Scheme Procedure} program-file @var{name} @var{exp} @
4003 Return an object representing the executable store item @var{name} that
4004 runs @var{gexp}. @var{guile} is the Guile package used to execute that
4007 This is the declarative counterpart of @code{gexp->script}.
4010 @deffn {Monadic Procedure} gexp->file @var{name} @var{exp} @
4011 [#:set-load-path? #t]
4012 Return a derivation that builds a file @var{name} containing @var{exp}.
4013 When @var{set-load-path?} is true, emit code in the resulting file to
4014 set @code{%load-path} and @code{%load-compiled-path} to honor
4015 @var{exp}'s imported modules.
4017 The resulting file holds references to all the dependencies of @var{exp}
4018 or a subset thereof.
4021 @deffn {Scheme Procedure} scheme-file @var{name} @var{exp}
4022 Return an object representing the Scheme file @var{name} that contains
4025 This is the declarative counterpart of @code{gexp->file}.
4028 @deffn {Monadic Procedure} text-file* @var{name} @var{text} @dots{}
4029 Return as a monadic value a derivation that builds a text file
4030 containing all of @var{text}. @var{text} may list, in addition to
4031 strings, objects of any type that can be used in a gexp: packages,
4032 derivations, local file objects, etc. The resulting store file holds
4033 references to all these.
4035 This variant should be preferred over @code{text-file} anytime the file
4036 to create will reference items from the store. This is typically the
4037 case when building a configuration file that embeds store file names,
4041 (define (profile.sh)
4042 ;; Return the name of a shell script in the store that
4043 ;; initializes the 'PATH' environment variable.
4044 (text-file* "profile.sh"
4045 "export PATH=" coreutils "/bin:"
4046 grep "/bin:" sed "/bin\n"))
4049 In this example, the resulting @file{/gnu/store/@dots{}-profile.sh} file
4050 will reference @var{coreutils}, @var{grep}, and @var{sed}, thereby
4051 preventing them from being garbage-collected during its lifetime.
4054 @deffn {Scheme Procedure} mixed-text-file @var{name} @var{text} @dots{}
4055 Return an object representing store file @var{name} containing
4056 @var{text}. @var{text} is a sequence of strings and file-like objects,
4060 (mixed-text-file "profile"
4061 "export PATH=" coreutils "/bin:" grep "/bin")
4064 This is the declarative counterpart of @code{text-file*}.
4067 Of course, in addition to gexps embedded in ``host'' code, there are
4068 also modules containing build tools. To make it clear that they are
4069 meant to be used in the build stratum, these modules are kept in the
4070 @code{(guix build @dots{})} name space.
4072 @cindex lowering, of high-level objects in gexps
4073 Internally, high-level objects are @dfn{lowered}, using their compiler,
4074 to either derivations or store items. For instance, lowering a package
4075 yields a derivation, and lowering a @code{plain-file} yields a store
4076 item. This is achieved using the @code{lower-object} monadic procedure.
4078 @deffn {Monadic Procedure} lower-object @var{obj} [@var{system}] @
4080 Return as a value in @var{%store-monad} the derivation or store item
4081 corresponding to @var{obj} for @var{system}, cross-compiling for
4082 @var{target} if @var{target} is true. @var{obj} must be an object that
4083 has an associated gexp compiler, such as a @code{<package>}.
4087 @c *********************************************************************
4091 This section describes Guix command-line utilities. Some of them are
4092 primarily targeted at developers and users who write new package
4093 definitions, while others are more generally useful. They complement
4094 the Scheme programming interface of Guix in a convenient way.
4097 * Invoking guix build:: Building packages from the command line.
4098 * Invoking guix edit:: Editing package definitions.
4099 * Invoking guix download:: Downloading a file and printing its hash.
4100 * Invoking guix hash:: Computing the cryptographic hash of a file.
4101 * Invoking guix import:: Importing package definitions.
4102 * Invoking guix refresh:: Updating package definitions.
4103 * Invoking guix lint:: Finding errors in package definitions.
4104 * Invoking guix size:: Profiling disk usage.
4105 * Invoking guix graph:: Visualizing the graph of packages.
4106 * Invoking guix environment:: Setting up development environments.
4107 * Invoking guix publish:: Sharing substitutes.
4108 * Invoking guix challenge:: Challenging substitute servers.
4109 * Invoking guix container:: Process isolation.
4112 @node Invoking guix build
4113 @section Invoking @command{guix build}
4115 The @command{guix build} command builds packages or derivations and
4116 their dependencies, and prints the resulting store paths. Note that it
4117 does not modify the user's profile---this is the job of the
4118 @command{guix package} command (@pxref{Invoking guix package}). Thus,
4119 it is mainly useful for distribution developers.
4121 The general syntax is:
4124 guix build @var{options} @var{package-or-derivation}@dots{}
4127 As an example, the following command builds the latest versions of Emacs
4128 and of Guile, displays their build logs, and finally displays the
4129 resulting directories:
4132 guix build emacs guile
4135 Similarly, the following command builds all the available packages:
4138 guix build --quiet --keep-going \
4139 `guix package -A | cut -f1,2 --output-delimiter=@@`
4142 @var{package-or-derivation} may be either the name of a package found in
4143 the software distribution such as @code{coreutils} or
4144 @code{coreutils-8.20}, or a derivation such as
4145 @file{/gnu/store/@dots{}-coreutils-8.19.drv}. In the former case, a
4146 package with the corresponding name (and optionally version) is searched
4147 for among the GNU distribution modules (@pxref{Package Modules}).
4149 Alternatively, the @code{--expression} option may be used to specify a
4150 Scheme expression that evaluates to a package; this is useful when
4151 disambiguating among several same-named packages or package variants is
4154 There may be zero or more @var{options}. The available options are
4155 described in the subsections below.
4158 * Common Build Options:: Build options for most commands.
4159 * Package Transformation Options:: Creating variants of packages.
4160 * Additional Build Options:: Options specific to 'guix build'.
4163 @node Common Build Options
4164 @subsection Common Build Options
4166 A number of options that control the build process are common to
4167 @command{guix build} and other commands that can spawn builds, such as
4168 @command{guix package} or @command{guix archive}. These are the
4173 @item --load-path=@var{directory}
4174 @itemx -L @var{directory}
4175 Add @var{directory} to the front of the package module search path
4176 (@pxref{Package Modules}).
4178 This allows users to define their own packages and make them visible to
4179 the command-line tools.
4183 Keep the build tree of failed builds. Thus, if a build fails, its build
4184 tree is kept under @file{/tmp}, in a directory whose name is shown at
4185 the end of the build log. This is useful when debugging build issues.
4189 Keep going when some of the derivations fail to build; return only once
4190 all the builds have either completed or failed.
4192 The default behavior is to stop as soon as one of the specified
4193 derivations has failed.
4197 Do not build the derivations.
4200 When substituting a pre-built binary fails, fall back to building
4203 @item --substitute-urls=@var{urls}
4204 @anchor{client-substitute-urls}
4205 Consider @var{urls} the whitespace-separated list of substitute source
4206 URLs, overriding the default list of URLs of @command{guix-daemon}
4207 (@pxref{daemon-substitute-urls,, @command{guix-daemon} URLs}).
4209 This means that substitutes may be downloaded from @var{urls}, provided
4210 they are signed by a key authorized by the system administrator
4211 (@pxref{Substitutes}).
4213 When @var{urls} is the empty string, substitutes are effectively
4216 @item --no-substitutes
4217 Do not use substitutes for build products. That is, always build things
4218 locally instead of allowing downloads of pre-built binaries
4219 (@pxref{Substitutes}).
4222 Do not ``graft'' packages. In practice, this means that package updates
4223 available as grafts are not applied. @xref{Security Updates}, for more
4224 information on grafts.
4226 @item --rounds=@var{n}
4227 Build each derivation @var{n} times in a row, and raise an error if
4228 consecutive build results are not bit-for-bit identical.
4230 This is a useful way to detect non-deterministic builds processes.
4231 Non-deterministic build processes are a problem because they make it
4232 practically impossible for users to @emph{verify} whether third-party
4233 binaries are genuine. @xref{Invoking guix challenge}, for more.
4235 Note that, currently, the differing build results are not kept around,
4236 so you will have to manually investigate in case of an error---e.g., by
4237 stashing one of the build results with @code{guix archive --export}
4238 (@pxref{Invoking guix archive}), then rebuilding, and finally comparing
4241 @item --no-build-hook
4242 Do not attempt to offload builds @i{via} the ``build hook'' of the daemon
4243 (@pxref{Daemon Offload Setup}). That is, always build things locally
4244 instead of offloading builds to remote machines.
4246 @item --max-silent-time=@var{seconds}
4247 When the build or substitution process remains silent for more than
4248 @var{seconds}, terminate it and report a build failure.
4250 @item --timeout=@var{seconds}
4251 Likewise, when the build or substitution process lasts for more than
4252 @var{seconds}, terminate it and report a build failure.
4254 By default there is no timeout. This behavior can be restored with
4257 @item --verbosity=@var{level}
4258 Use the given verbosity level. @var{level} must be an integer between 0
4259 and 5; higher means more verbose output. Setting a level of 4 or more
4260 may be helpful when debugging setup issues with the build daemon.
4262 @item --cores=@var{n}
4264 Allow the use of up to @var{n} CPU cores for the build. The special
4265 value @code{0} means to use as many CPU cores as available.
4267 @item --max-jobs=@var{n}
4269 Allow at most @var{n} build jobs in parallel. @xref{Invoking
4270 guix-daemon, @code{--max-jobs}}, for details about this option and the
4271 equivalent @command{guix-daemon} option.
4275 Behind the scenes, @command{guix build} is essentially an interface to
4276 the @code{package-derivation} procedure of the @code{(guix packages)}
4277 module, and to the @code{build-derivations} procedure of the @code{(guix
4278 derivations)} module.
4280 In addition to options explicitly passed on the command line,
4281 @command{guix build} and other @command{guix} commands that support
4282 building honor the @code{GUIX_BUILD_OPTIONS} environment variable.
4284 @defvr {Environment Variable} GUIX_BUILD_OPTIONS
4285 Users can define this variable to a list of command line options that
4286 will automatically be used by @command{guix build} and other
4287 @command{guix} commands that can perform builds, as in the example
4291 $ export GUIX_BUILD_OPTIONS="--no-substitutes -c 2 -L /foo/bar"
4294 These options are parsed independently, and the result is appended to
4295 the parsed command-line options.
4299 @node Package Transformation Options
4300 @subsection Package Transformation Options
4302 @cindex package variants
4303 Another set of command-line options supported by @command{guix build}
4304 and also @command{guix package} are @dfn{package transformation
4305 options}. These are options that make it possible to define @dfn{package
4306 variants}---for instance, packages built from different source code.
4307 This is a convenient way to create customized packages on the fly
4308 without having to type in the definitions of package variants
4309 (@pxref{Defining Packages}).
4313 @item --with-source=@var{source}
4314 Use @var{source} as the source of the corresponding package.
4315 @var{source} must be a file name or a URL, as for @command{guix
4316 download} (@pxref{Invoking guix download}).
4318 The ``corresponding package'' is taken to be the one specified on the
4319 command line the name of which matches the base of @var{source}---e.g.,
4320 if @var{source} is @code{/src/guile-2.0.10.tar.gz}, the corresponding
4321 package is @code{guile}. Likewise, the version string is inferred from
4322 @var{source}; in the previous example, it is @code{2.0.10}.
4324 This option allows users to try out versions of packages other than the
4325 one provided by the distribution. The example below downloads
4326 @file{ed-1.7.tar.gz} from a GNU mirror and uses that as the source for
4327 the @code{ed} package:
4330 guix build ed --with-source=mirror://gnu/ed/ed-1.7.tar.gz
4333 As a developer, @code{--with-source} makes it easy to test release
4337 guix build guile --with-source=../guile-2.0.9.219-e1bb7.tar.xz
4340 @dots{} or to build from a checkout in a pristine environment:
4343 $ git clone git://git.sv.gnu.org/guix.git
4344 $ guix build guix --with-source=./guix
4347 @item --with-input=@var{package}=@var{replacement}
4348 Replace dependency on @var{package} by a dependency on
4349 @var{replacement}. @var{package} must be a package name, and
4350 @var{replacement} must be a package specification such as @code{guile}
4351 or @code{guile@@1.8}.
4353 For instance, the following command builds Guix, but replaces its
4354 dependency on the current stable version of Guile with a dependency on
4355 the development version of Guile, @code{guile-next}:
4358 guix build --with-input=guile=guile-next guix
4361 This is a recursive, deep replacement. So in this example, both
4362 @code{guix} and its dependency @code{guile-json} (which also depends on
4363 @code{guile}) get rebuilt against @code{guile-next}.
4365 However, implicit inputs are left unchanged.
4368 @node Additional Build Options
4369 @subsection Additional Build Options
4371 The command-line options presented below are specific to @command{guix
4378 Build quietly, without displaying the build log. Upon completion, the
4379 build log is kept in @file{/var} (or similar) and can always be
4380 retrieved using the @option{--log-file} option.
4382 @item --file=@var{file}
4383 @itemx -f @var{file}
4385 Build the package or derivation that the code within @var{file}
4388 As an example, @var{file} might contain a package definition like this
4389 (@pxref{Defining Packages}):
4392 @verbatiminclude package-hello.scm
4395 @item --expression=@var{expr}
4396 @itemx -e @var{expr}
4397 Build the package or derivation @var{expr} evaluates to.
4399 For example, @var{expr} may be @code{(@@ (gnu packages guile)
4400 guile-1.8)}, which unambiguously designates this specific variant of
4401 version 1.8 of Guile.
4403 Alternatively, @var{expr} may be a G-expression, in which case it is used
4404 as a build program passed to @code{gexp->derivation}
4405 (@pxref{G-Expressions}).
4407 Lastly, @var{expr} may refer to a zero-argument monadic procedure
4408 (@pxref{The Store Monad}). The procedure must return a derivation as a
4409 monadic value, which is then passed through @code{run-with-store}.
4413 Build the source derivations of the packages, rather than the packages
4416 For instance, @code{guix build -S gcc} returns something like
4417 @file{/gnu/store/@dots{}-gcc-4.7.2.tar.bz2}, which is the GCC
4420 The returned source tarball is the result of applying any patches and
4421 code snippets specified in the package @code{origin} (@pxref{Defining
4425 Fetch and return the source of @var{package-or-derivation} and all their
4426 dependencies, recursively. This is a handy way to obtain a local copy
4427 of all the source code needed to build @var{packages}, allowing you to
4428 eventually build them even without network access. It is an extension
4429 of the @code{--source} option and can accept one of the following
4430 optional argument values:
4434 This value causes the @code{--sources} option to behave in the same way
4435 as the @code{--source} option.
4438 Build the source derivations of all packages, including any source that
4439 might be listed as @code{inputs}. This is the default value.
4442 $ guix build --sources tzdata
4443 The following derivations will be built:
4444 /gnu/store/@dots{}-tzdata2015b.tar.gz.drv
4445 /gnu/store/@dots{}-tzcode2015b.tar.gz.drv
4449 Build the source derivations of all packages, as well of all transitive
4450 inputs to the packages. This can be used e.g. to
4451 prefetch package source for later offline building.
4454 $ guix build --sources=transitive tzdata
4455 The following derivations will be built:
4456 /gnu/store/@dots{}-tzcode2015b.tar.gz.drv
4457 /gnu/store/@dots{}-findutils-4.4.2.tar.xz.drv
4458 /gnu/store/@dots{}-grep-2.21.tar.xz.drv
4459 /gnu/store/@dots{}-coreutils-8.23.tar.xz.drv
4460 /gnu/store/@dots{}-make-4.1.tar.xz.drv
4461 /gnu/store/@dots{}-bash-4.3.tar.xz.drv
4467 @item --system=@var{system}
4468 @itemx -s @var{system}
4469 Attempt to build for @var{system}---e.g., @code{i686-linux}---instead of
4470 the system type of the build host.
4472 An example use of this is on Linux-based systems, which can emulate
4473 different personalities. For instance, passing
4474 @code{--system=i686-linux} on an @code{x86_64-linux} system allows users
4475 to build packages in a complete 32-bit environment.
4477 @item --target=@var{triplet}
4478 @cindex cross-compilation
4479 Cross-build for @var{triplet}, which must be a valid GNU triplet, such
4480 as @code{"mips64el-linux-gnu"} (@pxref{Configuration Names, GNU
4481 configuration triplets,, configure, GNU Configure and Build System}).
4483 @anchor{build-check}
4485 @cindex determinism, checking
4486 @cindex reproducibility, checking
4487 Rebuild @var{package-or-derivation}, which are already available in the
4488 store, and raise an error if the build results are not bit-for-bit
4491 This mechanism allows you to check whether previously installed
4492 substitutes are genuine (@pxref{Substitutes}), or whether the build result
4493 of a package is deterministic. @xref{Invoking guix challenge}, for more
4494 background information and tools.
4496 When used in conjunction with @option{--keep-failed}, the differing
4497 output is kept in the store, under @file{/gnu/store/@dots{}-check}.
4498 This makes it easy to look for differences between the two results.
4502 Return the derivation paths, not the output paths, of the given
4505 @item --root=@var{file}
4506 @itemx -r @var{file}
4507 Make @var{file} a symlink to the result, and register it as a garbage
4511 Return the build log file names or URLs for the given
4512 @var{package-or-derivation}, or raise an error if build logs are
4515 This works regardless of how packages or derivations are specified. For
4516 instance, the following invocations are equivalent:
4519 guix build --log-file `guix build -d guile`
4520 guix build --log-file `guix build guile`
4521 guix build --log-file guile
4522 guix build --log-file -e '(@@ (gnu packages guile) guile-2.0)'
4525 If a log is unavailable locally, and unless @code{--no-substitutes} is
4526 passed, the command looks for a corresponding log on one of the
4527 substitute servers (as specified with @code{--substitute-urls}.)
4529 So for instance, imagine you want to see the build log of GDB on MIPS,
4530 but you are actually on an @code{x86_64} machine:
4533 $ guix build --log-file gdb -s mips64el-linux
4534 https://hydra.gnu.org/log/@dots{}-gdb-7.10
4537 You can freely access a huge library of build logs!
4541 @node Invoking guix edit
4542 @section Invoking @command{guix edit}
4544 @cindex package definition, editing
4545 So many packages, so many source files! The @command{guix edit} command
4546 facilitates the life of users and packagers by pointing their editor at
4547 the source file containing the definition of the specified packages.
4551 guix edit gcc@@4.9 vim
4555 launches the program specified in the @code{VISUAL} or in the
4556 @code{EDITOR} environment variable to view the recipe of GCC@tie{}4.9.3
4559 If you are using a Guix Git checkout (@pxref{Building from Git}), or
4560 have created your own packages on @code{GUIX_PACKAGE_PATH}
4561 (@pxref{Defining Packages}), you will be able to edit the package
4562 recipes. Otherwise, you will be able to examine the read-only recipes
4563 for packages currently in the store.
4565 If you are using Emacs, note that the Emacs user interface provides the
4566 @kbd{M-x guix-edit} command and a similar functionality in the ``package
4567 info'' and ``package list'' buffers created by the @kbd{M-x
4568 guix-search-by-name} and similar commands (@pxref{Emacs Commands}).
4571 @node Invoking guix download
4572 @section Invoking @command{guix download}
4574 When writing a package definition, developers typically need to download
4575 a source tarball, compute its SHA256 hash, and write that
4576 hash in the package definition (@pxref{Defining Packages}). The
4577 @command{guix download} tool helps with this task: it downloads a file
4578 from the given URI, adds it to the store, and prints both its file name
4579 in the store and its SHA256 hash.
4581 The fact that the downloaded file is added to the store saves bandwidth:
4582 when the developer eventually tries to build the newly defined package
4583 with @command{guix build}, the source tarball will not have to be
4584 downloaded again because it is already in the store. It is also a
4585 convenient way to temporarily stash files, which may be deleted
4586 eventually (@pxref{Invoking guix gc}).
4588 The @command{guix download} command supports the same URIs as used in
4589 package definitions. In particular, it supports @code{mirror://} URIs.
4590 @code{https} URIs (HTTP over TLS) are supported @emph{provided} the
4591 Guile bindings for GnuTLS are available in the user's environment; when
4592 they are not available, an error is raised. @xref{Guile Preparations,
4593 how to install the GnuTLS bindings for Guile,, gnutls-guile,
4594 GnuTLS-Guile}, for more information.
4596 The following option is available:
4599 @item --format=@var{fmt}
4601 Write the hash in the format specified by @var{fmt}. For more
4602 information on the valid values for @var{fmt}, @pxref{Invoking guix hash}.
4605 @node Invoking guix hash
4606 @section Invoking @command{guix hash}
4608 The @command{guix hash} command computes the SHA256 hash of a file.
4609 It is primarily a convenience tool for anyone contributing to the
4610 distribution: it computes the cryptographic hash of a file, which can be
4611 used in the definition of a package (@pxref{Defining Packages}).
4613 The general syntax is:
4616 guix hash @var{option} @var{file}
4619 @command{guix hash} has the following option:
4623 @item --format=@var{fmt}
4625 Write the hash in the format specified by @var{fmt}.
4627 Supported formats: @code{nix-base32}, @code{base32}, @code{base16}
4628 (@code{hex} and @code{hexadecimal} can be used as well).
4630 If the @option{--format} option is not specified, @command{guix hash}
4631 will output the hash in @code{nix-base32}. This representation is used
4632 in the definitions of packages.
4636 Compute the hash on @var{file} recursively.
4638 In this case, the hash is computed on an archive containing @var{file},
4639 including its children if it is a directory. Some of the metadata of
4640 @var{file} is part of the archive; for instance, when @var{file} is a
4641 regular file, the hash is different depending on whether @var{file} is
4642 executable or not. Metadata such as time stamps has no impact on the
4643 hash (@pxref{Invoking guix archive}).
4644 @c FIXME: Replace xref above with xref to an ``Archive'' section when
4648 As an example, here is how you would compute the hash of a Git checkout,
4649 which is useful when using the @code{git-fetch} method (@pxref{origin
4653 $ git clone http://example.org/foo.git
4660 @node Invoking guix import
4661 @section Invoking @command{guix import}
4663 @cindex importing packages
4664 @cindex package import
4665 @cindex package conversion
4666 The @command{guix import} command is useful for people who would like to
4667 add a package to the distribution with as little work as
4668 possible---a legitimate demand. The command knows of a few
4669 repositories from which it can ``import'' package metadata. The result
4670 is a package definition, or a template thereof, in the format we know
4671 (@pxref{Defining Packages}).
4673 The general syntax is:
4676 guix import @var{importer} @var{options}@dots{}
4679 @var{importer} specifies the source from which to import package
4680 metadata, and @var{options} specifies a package identifier and other
4681 options specific to @var{importer}. Currently, the available
4686 Import metadata for the given GNU package. This provides a template
4687 for the latest version of that GNU package, including the hash of its
4688 source tarball, and its canonical synopsis and description.
4690 Additional information such as the package dependencies and its
4691 license needs to be figured out manually.
4693 For example, the following command returns a package definition for
4697 guix import gnu hello
4700 Specific command-line options are:
4703 @item --key-download=@var{policy}
4704 As for @code{guix refresh}, specify the policy to handle missing OpenPGP
4705 keys when verifying the package signature. @xref{Invoking guix
4706 refresh, @code{--key-download}}.
4711 Import metadata from the @uref{https://pypi.python.org/, Python Package
4712 Index}@footnote{This functionality requires Guile-JSON to be installed.
4713 @xref{Requirements}.}. Information is taken from the JSON-formatted
4714 description available at @code{pypi.python.org} and usually includes all
4715 the relevant information, including package dependencies. For maximum
4716 efficiency, it is recommended to install the @command{unzip} utility, so
4717 that the importer can unzip Python wheels and gather data from them.
4719 The command below imports metadata for the @code{itsdangerous} Python
4723 guix import pypi itsdangerous
4728 Import metadata from @uref{https://rubygems.org/,
4729 RubyGems}@footnote{This functionality requires Guile-JSON to be
4730 installed. @xref{Requirements}.}. Information is taken from the
4731 JSON-formatted description available at @code{rubygems.org} and includes
4732 most relevant information, including runtime dependencies. There are
4733 some caveats, however. The metadata doesn't distinguish between
4734 synopses and descriptions, so the same string is used for both fields.
4735 Additionally, the details of non-Ruby dependencies required to build
4736 native extensions is unavailable and left as an exercise to the
4739 The command below imports metadata for the @code{rails} Ruby package:
4742 guix import gem rails
4747 Import metadata from @uref{https://www.metacpan.org/, MetaCPAN}@footnote{This
4748 functionality requires Guile-JSON to be installed.
4749 @xref{Requirements}.}.
4750 Information is taken from the JSON-formatted metadata provided through
4751 @uref{https://api.metacpan.org/, MetaCPAN's API} and includes most
4752 relevant information, such as module dependencies. License information
4753 should be checked closely. If Perl is available in the store, then the
4754 @code{corelist} utility will be used to filter core modules out of the
4755 list of dependencies.
4757 The command command below imports metadata for the @code{Acme::Boolean}
4761 guix import cpan Acme::Boolean
4766 @cindex Bioconductor
4767 Import metadata from @uref{http://cran.r-project.org/, CRAN}, the
4768 central repository for the @uref{http://r-project.org, GNU@tie{}R
4769 statistical and graphical environment}.
4771 Information is extracted from the @code{DESCRIPTION} file of the package.
4773 The command command below imports metadata for the @code{Cairo}
4777 guix import cran Cairo
4780 When @code{--archive=bioconductor} is added, metadata is imported from
4781 @uref{http://www.bioconductor.org/, Bioconductor}, a repository of R
4782 packages for for the analysis and comprehension of high-throughput
4783 genomic data in bioinformatics.
4785 Information is extracted from the @code{DESCRIPTION} file of a package
4786 published on the web interface of the Bioconductor SVN repository.
4788 The command below imports metadata for the @code{GenomicRanges}
4792 guix import cran --archive=bioconductor GenomicRanges
4796 Import metadata from a local copy of the source of the
4797 @uref{http://nixos.org/nixpkgs/, Nixpkgs distribution}@footnote{This
4798 relies on the @command{nix-instantiate} command of
4799 @uref{http://nixos.org/nix/, Nix}.}. Package definitions in Nixpkgs are
4800 typically written in a mixture of Nix-language and Bash code. This
4801 command only imports the high-level package structure that is written in
4802 the Nix language. It normally includes all the basic fields of a
4805 When importing a GNU package, the synopsis and descriptions are replaced
4806 by their canonical upstream variant.
4808 Usually, you will first need to do:
4811 export NIX_REMOTE=daemon
4815 so that @command{nix-instantiate} does not try to open the Nix database.
4817 As an example, the command below imports the package definition of
4818 LibreOffice (more precisely, it imports the definition of the package
4819 bound to the @code{libreoffice} top-level attribute):
4822 guix import nix ~/path/to/nixpkgs libreoffice
4827 Import metadata from the Haskell community's central package archive
4828 @uref{https://hackage.haskell.org/, Hackage}. Information is taken from
4829 Cabal files and includes all the relevant information, including package
4832 Specific command-line options are:
4837 Read a Cabal file from standard input.
4838 @item --no-test-dependencies
4840 Do not include dependencies required only by the test suites.
4841 @item --cabal-environment=@var{alist}
4842 @itemx -e @var{alist}
4843 @var{alist} is a Scheme alist defining the environment in which the
4844 Cabal conditionals are evaluated. The accepted keys are: @code{os},
4845 @code{arch}, @code{impl} and a string representing the name of a flag.
4846 The value associated with a flag has to be either the symbol
4847 @code{true} or @code{false}. The value associated with other keys
4848 has to conform to the Cabal file format definition. The default value
4849 associated with the keys @code{os}, @code{arch} and @code{impl} is
4850 @samp{linux}, @samp{x86_64} and @samp{ghc}, respectively.
4853 The command below imports metadata for the latest version of the
4854 @code{HTTP} Haskell package without including test dependencies and
4855 specifying the value of the flag @samp{network-uri} as @code{false}:
4858 guix import hackage -t -e "'((\"network-uri\" . false))" HTTP
4861 A specific package version may optionally be specified by following the
4862 package name by an at-sign and a version number as in the following example:
4865 guix import hackage mtl@@2.1.3.1
4870 Import metadata from an Emacs Lisp Package Archive (ELPA) package
4871 repository (@pxref{Packages,,, emacs, The GNU Emacs Manual}).
4873 Specific command-line options are:
4876 @item --archive=@var{repo}
4877 @itemx -a @var{repo}
4878 @var{repo} identifies the archive repository from which to retrieve the
4879 information. Currently the supported repositories and their identifiers
4883 @uref{http://elpa.gnu.org/packages, GNU}, selected by the @code{gnu}
4884 identifier. This is the default.
4887 @uref{http://stable.melpa.org/packages, MELPA-Stable}, selected by the
4888 @code{melpa-stable} identifier.
4891 @uref{http://melpa.org/packages, MELPA}, selected by the @code{melpa}
4897 The structure of the @command{guix import} code is modular. It would be
4898 useful to have more importers for other package formats, and your help
4899 is welcome here (@pxref{Contributing}).
4901 @node Invoking guix refresh
4902 @section Invoking @command{guix refresh}
4904 The primary audience of the @command{guix refresh} command is developers
4905 of the GNU software distribution. By default, it reports any packages
4906 provided by the distribution that are outdated compared to the latest
4907 upstream version, like this:
4911 gnu/packages/gettext.scm:29:13: gettext would be upgraded from 0.18.1.1 to 0.18.2.1
4912 gnu/packages/glib.scm:77:12: glib would be upgraded from 2.34.3 to 2.37.0
4915 It does so by browsing the FTP directory of each package and determining
4916 the highest version number of the source tarballs therein. The command
4917 knows how to update specific types of packages: GNU packages, ELPA
4918 packages, etc.---see the documentation for @option{--type} below. The
4919 are many packages, though, for which it lacks a method to determine
4920 whether a new upstream release is available. However, the mechanism is
4921 extensible, so feel free to get in touch with us to add a new method!
4923 When passed @code{--update}, it modifies distribution source files to
4924 update the version numbers and source tarball hashes of those package
4925 recipes (@pxref{Defining Packages}). This is achieved by downloading
4926 each package's latest source tarball and its associated OpenPGP
4927 signature, authenticating the downloaded tarball against its signature
4928 using @command{gpg}, and finally computing its hash. When the public
4929 key used to sign the tarball is missing from the user's keyring, an
4930 attempt is made to automatically retrieve it from a public key server;
4931 when this is successful, the key is added to the user's keyring; otherwise,
4932 @command{guix refresh} reports an error.
4934 The following options are supported:
4938 @item --expression=@var{expr}
4939 @itemx -e @var{expr}
4940 Consider the package @var{expr} evaluates to.
4942 This is useful to precisely refer to a package, as in this example:
4945 guix refresh -l -e '(@@@@ (gnu packages commencement) glibc-final)'
4948 This command lists the dependents of the ``final'' libc (essentially all
4953 Update distribution source files (package recipes) in place. This is
4954 usually run from a checkout of the Guix source tree (@pxref{Running
4955 Guix Before It Is Installed}):
4958 $ ./pre-inst-env guix refresh -s non-core
4961 @xref{Defining Packages}, for more information on package definitions.
4963 @item --select=[@var{subset}]
4964 @itemx -s @var{subset}
4965 Select all the packages in @var{subset}, one of @code{core} or
4968 The @code{core} subset refers to all the packages at the core of the
4969 distribution---i.e., packages that are used to build ``everything
4970 else''. This includes GCC, libc, Binutils, Bash, etc. Usually,
4971 changing one of these packages in the distribution entails a rebuild of
4972 all the others. Thus, such updates are an inconvenience to users in
4973 terms of build time or bandwidth used to achieve the upgrade.
4975 The @code{non-core} subset refers to the remaining packages. It is
4976 typically useful in cases where an update of the core packages would be
4979 @item --type=@var{updater}
4980 @itemx -t @var{updater}
4981 Select only packages handled by @var{updater} (may be a comma-separated
4982 list of updaters). Currently, @var{updater} may be one of:
4986 the updater for GNU packages;
4988 the updater for GNOME packages;
4990 the updater for KDE packages;
4992 the updater for X.org packages;
4994 the updater for @uref{http://elpa.gnu.org/, ELPA} packages;
4996 the updater for @uref{http://cran.r-project.org/, CRAN} packages;
4998 the updater for @uref{http://www.bioconductor.org/, Bioconductor} R packages;
5000 the updater for @uref{https://pypi.python.org, PyPI} packages.
5002 the updater for @uref{https://rubygems.org, RubyGems} packages.
5004 the updater for @uref{https://github.com, GitHub} packages.
5006 the updater for @uref{https://hackage.haskell.org, Hackage} packages.
5009 For instance, the following command only checks for updates of Emacs
5010 packages hosted at @code{elpa.gnu.org} and for updates of CRAN packages:
5013 $ guix refresh --type=elpa,cran
5014 gnu/packages/statistics.scm:819:13: r-testthat would be upgraded from 0.10.0 to 0.11.0
5015 gnu/packages/emacs.scm:856:13: emacs-auctex would be upgraded from 11.88.6 to 11.88.9
5020 In addition, @command{guix refresh} can be passed one or more package
5021 names, as in this example:
5024 $ ./pre-inst-env guix refresh -u emacs idutils gcc-4.8.4
5028 The command above specifically updates the @code{emacs} and
5029 @code{idutils} packages. The @code{--select} option would have no
5030 effect in this case.
5032 When considering whether to upgrade a package, it is sometimes
5033 convenient to know which packages would be affected by the upgrade and
5034 should be checked for compatibility. For this the following option may
5035 be used when passing @command{guix refresh} one or more package names:
5039 @item --list-updaters
5041 List available updaters and exit (see @option{--type} above.)
5043 @item --list-dependent
5045 List top-level dependent packages that would need to be rebuilt as a
5046 result of upgrading one or more packages.
5050 Be aware that the @code{--list-dependent} option only
5051 @emph{approximates} the rebuilds that would be required as a result of
5052 an upgrade. More rebuilds might be required under some circumstances.
5055 $ guix refresh --list-dependent flex
5056 Building the following 120 packages would ensure 213 dependent packages are rebuilt:
5057 hop-2.4.0 geiser-0.4 notmuch-0.18 mu-0.9.9.5 cflow-1.4 idutils-4.6 @dots{}
5060 The command above lists a set of packages that could be built to check
5061 for compatibility with an upgraded @code{flex} package.
5063 The following options can be used to customize GnuPG operation:
5067 @item --gpg=@var{command}
5068 Use @var{command} as the GnuPG 2.x command. @var{command} is searched
5069 for in @code{$PATH}.
5071 @item --key-download=@var{policy}
5072 Handle missing OpenPGP keys according to @var{policy}, which may be one
5077 Always download missing OpenPGP keys from the key server, and add them
5078 to the user's GnuPG keyring.
5081 Never try to download missing OpenPGP keys. Instead just bail out.
5084 When a package signed with an unknown OpenPGP key is encountered, ask
5085 the user whether to download it or not. This is the default behavior.
5088 @item --key-server=@var{host}
5089 Use @var{host} as the OpenPGP key server when importing a public key.
5093 The @code{github} updater uses the
5094 @uref{https://developer.github.com/v3/, GitHub API} to query for new
5095 releases. When used repeatedly e.g. when refreshing all packages,
5096 GitHub will eventually refuse to answer any further API requests. By
5097 default 60 API requests per hour are allowed, and a full refresh on all
5098 GitHub packages in Guix requires more than this. Authentication with
5099 GitHub through the use of an API token alleviates these limits. To use
5100 an API token, set the environment variable @code{GUIX_GITHUB_TOKEN} to a
5101 token procured from @uref{https://github.com/settings/tokens} or
5105 @node Invoking guix lint
5106 @section Invoking @command{guix lint}
5107 The @command{guix lint} command is meant to help package developers avoid
5108 common errors and use a consistent style. It runs a number of checks on
5109 a given set of packages in order to find common mistakes in their
5110 definitions. Available @dfn{checkers} include (see
5111 @code{--list-checkers} for a complete list):
5116 Validate certain typographical and stylistic rules about package
5117 descriptions and synopses.
5119 @item inputs-should-be-native
5120 Identify inputs that should most likely be native inputs.
5124 @itemx source-file-name
5125 Probe @code{home-page} and @code{source} URLs and report those that are
5126 invalid. Check that the source file name is meaningful, e.g. is not
5127 just a version number or ``git-checkout'', without a declared
5128 @code{file-name} (@pxref{origin Reference}).
5131 @cindex security vulnerabilities
5132 @cindex CVE, Common Vulnerabilities and Exposures
5133 Report known vulnerabilities found in the Common Vulnerabilities and
5134 Exposures (CVE) databases of the current and past year
5135 @uref{https://nvd.nist.gov/download.cfm#CVE_FEED, published by the US
5138 To view information about a particular vulnerability, visit pages such as:
5142 @indicateurl{https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-YYYY-ABCD}
5144 @indicateurl{https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-YYYY-ABCD}
5148 where @code{CVE-YYYY-ABCD} is the CVE identifier---e.g.,
5149 @code{CVE-2015-7554}.
5151 Package developers can specify in package recipes the
5152 @uref{https://nvd.nist.gov/cpe.cfm,Common Platform Enumeration (CPE)}
5153 name and version of the package when they differ from the name that Guix
5154 uses, as in this example:
5160 ;; CPE calls this package "grub2".
5161 (properties '((cpe-name . "grub2"))))
5165 Warn about obvious source code formatting issues: trailing white space,
5166 use of tabulations, etc.
5169 The general syntax is:
5172 guix lint @var{options} @var{package}@dots{}
5175 If no package is given on the command line, then all packages are checked.
5176 The @var{options} may be zero or more of the following:
5179 @item --list-checkers
5181 List and describe all the available checkers that will be run on packages
5186 Only enable the checkers specified in a comma-separated list using the
5187 names returned by @code{--list-checkers}.
5191 @node Invoking guix size
5192 @section Invoking @command{guix size}
5194 The @command{guix size} command helps package developers profile the
5195 disk usage of packages. It is easy to overlook the impact of an
5196 additional dependency added to a package, or the impact of using a
5197 single output for a package that could easily be split (@pxref{Packages
5198 with Multiple Outputs}). Such are the typical issues that
5199 @command{guix size} can highlight.
5201 The command can be passed a package specification such as @code{gcc-4.8}
5202 or @code{guile:debug}, or a file name in the store. Consider this
5206 $ guix size coreutils
5207 store item total self
5208 /gnu/store/@dots{}-coreutils-8.23 70.0 13.9 19.8%
5209 /gnu/store/@dots{}-gmp-6.0.0a 55.3 2.5 3.6%
5210 /gnu/store/@dots{}-acl-2.2.52 53.7 0.5 0.7%
5211 /gnu/store/@dots{}-attr-2.4.46 53.2 0.3 0.5%
5212 /gnu/store/@dots{}-gcc-4.8.4-lib 52.9 15.7 22.4%
5213 /gnu/store/@dots{}-glibc-2.21 37.2 37.2 53.1%
5217 The store items listed here constitute the @dfn{transitive closure} of
5218 Coreutils---i.e., Coreutils and all its dependencies, recursively---as
5219 would be returned by:
5222 $ guix gc -R /gnu/store/@dots{}-coreutils-8.23
5225 Here the output shows three columns next to store items. The first column,
5226 labeled ``total'', shows the size in mebibytes (MiB) of the closure of
5227 the store item---that is, its own size plus the size of all its
5228 dependencies. The next column, labeled ``self'', shows the size of the
5229 item itself. The last column shows the ratio of the size of the item
5230 itself to the space occupied by all the items listed here.
5232 In this example, we see that the closure of Coreutils weighs in at
5233 70@tie{}MiB, half of which is taken by libc. (That libc represents a
5234 large fraction of the closure is not a problem @i{per se} because it is
5235 always available on the system anyway.)
5237 When the package passed to @command{guix size} is available in the
5238 store, @command{guix size} queries the daemon to determine its
5239 dependencies, and measures its size in the store, similar to @command{du
5240 -ms --apparent-size} (@pxref{du invocation,,, coreutils, GNU
5243 When the given package is @emph{not} in the store, @command{guix size}
5244 reports information based on the available substitutes
5245 (@pxref{Substitutes}). This makes it possible it to profile disk usage of
5246 store items that are not even on disk, only available remotely.
5248 You can also specify several package names:
5251 $ guix size coreutils grep sed bash
5252 store item total self
5253 /gnu/store/@dots{}-coreutils-8.24 77.8 13.8 13.4%
5254 /gnu/store/@dots{}-grep-2.22 73.1 0.8 0.8%
5255 /gnu/store/@dots{}-bash-4.3.42 72.3 4.7 4.6%
5256 /gnu/store/@dots{}-readline-6.3 67.6 1.2 1.2%
5262 In this example we see that the combination of the four packages takes
5263 102.3@tie{}MiB in total, which is much less than the sum of each closure
5264 since they have a lot of dependencies in common.
5266 The available options are:
5270 @item --substitute-urls=@var{urls}
5271 Use substitute information from @var{urls}.
5272 @xref{client-substitute-urls, the same option for @code{guix build}}.
5274 @item --map-file=@var{file}
5275 Write a graphical map of disk usage in PNG format to @var{file}.
5277 For the example above, the map looks like this:
5279 @image{images/coreutils-size-map,5in,, map of Coreutils disk usage
5280 produced by @command{guix size}}
5282 This option requires that
5283 @uref{http://wingolog.org/software/guile-charting/, Guile-Charting} be
5284 installed and visible in Guile's module search path. When that is not
5285 the case, @command{guix size} fails as it tries to load it.
5287 @item --system=@var{system}
5288 @itemx -s @var{system}
5289 Consider packages for @var{system}---e.g., @code{x86_64-linux}.
5293 @node Invoking guix graph
5294 @section Invoking @command{guix graph}
5297 Packages and their dependencies form a @dfn{graph}, specifically a
5298 directed acyclic graph (DAG). It can quickly become difficult to have a
5299 mental model of the package DAG, so the @command{guix graph} command
5300 provides a visual representation of the DAG. @command{guix graph}
5301 emits a DAG representation in the input format of
5302 @uref{http://www.graphviz.org/, Graphviz}, so its output can be passed
5303 directly to the @command{dot} command of Graphviz. The general
5307 guix graph @var{options} @var{package}@dots{}
5310 For example, the following command generates a PDF file representing the
5311 package DAG for the GNU@tie{}Core Utilities, showing its build-time
5315 guix graph coreutils | dot -Tpdf > dag.pdf
5318 The output looks like this:
5320 @image{images/coreutils-graph,2in,,Dependency graph of the GNU Coreutils}
5322 Nice little graph, no?
5324 But there is more than one graph! The one above is concise: it is the
5325 graph of package objects, omitting implicit inputs such as GCC, libc,
5326 grep, etc. It is often useful to have such a concise graph, but
5327 sometimes one may want to see more details. @command{guix graph} supports
5328 several types of graphs, allowing you to choose the level of detail:
5332 This is the default type used in the example above. It shows the DAG of
5333 package objects, excluding implicit dependencies. It is concise, but
5334 filters out many details.
5337 This is the package DAG, @emph{including} implicit inputs.
5339 For instance, the following command:
5342 guix graph --type=bag-emerged coreutils | dot -Tpdf > dag.pdf
5345 ... yields this bigger graph:
5347 @image{images/coreutils-bag-graph,,5in,Detailed dependency graph of the GNU Coreutils}
5349 At the bottom of the graph, we see all the implicit inputs of
5350 @var{gnu-build-system} (@pxref{Build Systems, @code{gnu-build-system}}).
5352 Now, note that the dependencies of these implicit inputs---that is, the
5353 @dfn{bootstrap dependencies} (@pxref{Bootstrapping})---are not shown
5354 here, for conciseness.
5357 Similar to @code{bag-emerged}, but this time including all the bootstrap
5360 @item bag-with-origins
5361 Similar to @code{bag}, but also showing origins and their dependencies.
5364 This is the most detailed representation: It shows the DAG of
5365 derivations (@pxref{Derivations}) and plain store items. Compared to
5366 the above representation, many additional nodes are visible, including
5367 build scripts, patches, Guile modules, etc.
5369 For this type of graph, it is also possible to pass a @file{.drv} file
5370 name instead of a package name, as in:
5373 guix graph -t derivation `guix system build -d my-config.scm`
5377 All the types above correspond to @emph{build-time dependencies}. The
5378 following graph type represents the @emph{run-time dependencies}:
5382 This is the graph of @dfn{references} of a package output, as returned
5383 by @command{guix gc --references} (@pxref{Invoking guix gc}).
5385 If the given package output is not available in the store, @command{guix
5386 graph} attempts to obtain dependency information from substitutes.
5388 Here you can also pass a store file name instead of a package name. For
5389 example, the command below produces the reference graph of your profile
5390 (which can be big!):
5393 guix graph -t references `readlink -f ~/.guix-profile`
5397 The available options are the following:
5400 @item --type=@var{type}
5401 @itemx -t @var{type}
5402 Produce a graph output of @var{type}, where @var{type} must be one of
5403 the values listed above.
5406 List the supported graph types.
5408 @item --expression=@var{expr}
5409 @itemx -e @var{expr}
5410 Consider the package @var{expr} evaluates to.
5412 This is useful to precisely refer to a package, as in this example:
5415 guix graph -e '(@@@@ (gnu packages commencement) gnu-make-final)'
5420 @node Invoking guix environment
5421 @section Invoking @command{guix environment}
5423 @cindex reproducible build environments
5424 @cindex development environments
5425 The purpose of @command{guix environment} is to assist hackers in
5426 creating reproducible development environments without polluting their
5427 package profile. The @command{guix environment} tool takes one or more
5428 packages, builds all of their inputs, and creates a shell
5429 environment to use them.
5431 The general syntax is:
5434 guix environment @var{options} @var{package}@dots{}
5437 The following example spawns a new shell set up for the development of
5441 guix environment guile
5444 If the needed dependencies are not built yet, @command{guix environment}
5445 automatically builds them. The environment of the new shell is an augmented
5446 version of the environment that @command{guix environment} was run in.
5447 It contains the necessary search paths for building the given package
5448 added to the existing environment variables. To create a ``pure''
5449 environment, in which the original environment variables have been unset,
5450 use the @code{--pure} option@footnote{Users sometimes wrongfully augment
5451 environment variables such as @code{PATH} in their @file{~/.bashrc}
5452 file. As a consequence, when @code{guix environment} launches it, Bash
5453 may read @file{~/.bashrc}, thereby introducing ``impurities'' in these
5454 environment variables. It is an error to define such environment
5455 variables in @file{.bashrc}; instead, they should be defined in
5456 @file{.bash_profile}, which is sourced only by log-in shells.
5457 @xref{Bash Startup Files,,, bash, The GNU Bash Reference Manual}, for
5458 details on Bash start-up files.}.
5460 @vindex GUIX_ENVIRONMENT
5461 @command{guix environment} defines the @code{GUIX_ENVIRONMENT}
5462 variable in the shell it spawns; its value is the file name of the
5463 profile of this environment. This allows users to, say, define a
5464 specific prompt for development environments in their @file{.bashrc}
5465 (@pxref{Bash Startup Files,,, bash, The GNU Bash Reference Manual}):
5468 if [ -n "$GUIX_ENVIRONMENT" ]
5470 export PS1="\u@@\h \w [dev]\$ "
5475 ... or to browse the profile:
5478 $ ls "$GUIX_ENVIRONMENT/bin"
5481 Additionally, more than one package may be specified, in which case the
5482 union of the inputs for the given packages are used. For example, the
5483 command below spawns a shell where all of the dependencies of both Guile
5484 and Emacs are available:
5487 guix environment guile emacs
5490 Sometimes an interactive shell session is not desired. An arbitrary
5491 command may be invoked by placing the @code{--} token to separate the
5492 command from the rest of the arguments:
5495 guix environment guile -- make -j4
5498 In other situations, it is more convenient to specify the list of
5499 packages needed in the environment. For example, the following command
5500 runs @command{python} from an environment containing Python@tie{}2.7 and
5504 guix environment --ad-hoc python2-numpy python-2.7 -- python
5507 Furthermore, one might want the dependencies of a package and also some
5508 additional packages that are not build-time or runtime dependencies, but
5509 are useful when developing nonetheless. Because of this, the
5510 @code{--ad-hoc} flag is positional. Packages appearing before
5511 @code{--ad-hoc} are interpreted as packages whose dependencies will be
5512 added to the environment. Packages appearing after are interpreted as
5513 packages that will be added to the environment directly. For example,
5514 the following command creates a Guix development environment that
5515 additionally includes Git and strace:
5518 guix environment guix --ad-hoc git strace
5521 Sometimes it is desirable to isolate the environment as much as
5522 possible, for maximal purity and reproducibility. In particular, when
5523 using Guix on a host distro that is not GuixSD, it is desirable to
5524 prevent access to @file{/usr/bin} and other system-wide resources from
5525 the development environment. For example, the following command spawns
5526 a Guile REPL in a ``container'' where only the store and the current
5527 working directory are mounted:
5530 guix environment --ad-hoc --container guile -- guile
5534 The @code{--container} option requires Linux-libre 3.19 or newer.
5537 The available options are summarized below.
5540 @item --expression=@var{expr}
5541 @itemx -e @var{expr}
5542 Create an environment for the package or list of packages that
5543 @var{expr} evaluates to.
5545 For example, running:
5548 guix environment -e '(@@ (gnu packages maths) petsc-openmpi)'
5551 starts a shell with the environment for this specific variant of the
5557 guix environment --ad-hoc -e '(@@ (gnu) %base-packages)'
5560 starts a shell with all the GuixSD base packages available.
5562 The above commands only the use default output of the given packages.
5563 To select other outputs, two element tuples can be specified:
5566 guix environment --ad-hoc -e '(list (@ (gnu packages bash) bash) "include")'
5569 @item --load=@var{file}
5570 @itemx -l @var{file}
5571 Create an environment for the package or list of packages that the code
5572 within @var{file} evaluates to.
5574 As an example, @var{file} might contain a definition like this
5575 (@pxref{Defining Packages}):
5578 @verbatiminclude environment-gdb.scm
5582 Include all specified packages in the resulting environment, as if an
5583 @i{ad hoc} package were defined with them as inputs. This option is
5584 useful for quickly creating an environment without having to write a
5585 package expression to contain the desired inputs.
5587 For instance, the command:
5590 guix environment --ad-hoc guile guile-sdl -- guile
5593 runs @command{guile} in an environment where Guile and Guile-SDL are
5596 Note that this example implicitly asks for the default output of
5597 @code{guile} and @code{guile-sdl}, but it is possible to ask for a
5598 specific output---e.g., @code{glib:bin} asks for the @code{bin} output
5599 of @code{glib} (@pxref{Packages with Multiple Outputs}).
5601 This option may be composed with the default behavior of @command{guix
5602 environment}. Packages appearing before @code{--ad-hoc} are interpreted
5603 as packages whose dependencies will be added to the environment, the
5604 default behavior. Packages appearing after are interpreted as packages
5605 that will be added to the environment directly.
5608 Unset existing environment variables when building the new environment.
5609 This has the effect of creating an environment in which search paths
5610 only contain package inputs.
5612 @item --search-paths
5613 Display the environment variable definitions that make up the
5616 @item --system=@var{system}
5617 @itemx -s @var{system}
5618 Attempt to build for @var{system}---e.g., @code{i686-linux}.
5623 Run @var{command} within an isolated container. The current working
5624 directory outside the container is mapped inside the container.
5625 Additionally, a dummy home directory is created that matches the current
5626 user's home directory, and @file{/etc/passwd} is configured accordingly.
5627 The spawned process runs as the current user outside the container, but
5628 has root privileges in the context of the container.
5632 For containers, share the network namespace with the host system.
5633 Containers created without this flag only have access to the loopback
5636 @item --expose=@var{source}[=@var{target}]
5637 For containers, expose the file system @var{source} from the host system
5638 as the read-only file system @var{target} within the container. If
5639 @var{target} is not specified, @var{source} is used as the target mount
5640 point in the container.
5642 The example below spawns a Guile REPL in a container in which the user's
5643 home directory is accessible read-only via the @file{/exchange}
5647 guix environment --container --expose=$HOME=/exchange guile -- guile
5650 @item --share=@var{source}[=@var{target}]
5651 For containers, share the file system @var{source} from the host system
5652 as the writable file system @var{target} within the container. If
5653 @var{target} is not specified, @var{source} is used as the target mount
5654 point in the container.
5656 The example below spawns a Guile REPL in a container in which the user's
5657 home directory is accessible for both reading and writing via the
5658 @file{/exchange} directory:
5661 guix environment --container --share=$HOME=/exchange guile -- guile
5665 It also supports all of the common build options that @command{guix
5666 build} supports (@pxref{Common Build Options}).
5668 @node Invoking guix publish
5669 @section Invoking @command{guix publish}
5671 The purpose of @command{guix publish} is to enable users to easily share
5672 their store with others, who can then use it as a substitute server
5673 (@pxref{Substitutes}).
5675 When @command{guix publish} runs, it spawns an HTTP server which allows
5676 anyone with network access to obtain substitutes from it. This means
5677 that any machine running Guix can also act as if it were a build farm,
5678 since the HTTP interface is compatible with Hydra, the software behind
5679 the @code{hydra.gnu.org} build farm.
5681 For security, each substitute is signed, allowing recipients to check
5682 their authenticity and integrity (@pxref{Substitutes}). Because
5683 @command{guix publish} uses the signing key of the system, which is only
5684 readable by the system administrator, it must be started as root; the
5685 @code{--user} option makes it drop root privileges early on.
5687 The signing key pair must be generated before @command{guix publish} is
5688 launched, using @command{guix archive --generate-key} (@pxref{Invoking
5691 The general syntax is:
5694 guix publish @var{options}@dots{}
5697 Running @command{guix publish} without any additional arguments will
5698 spawn an HTTP server on port 8080:
5704 Once a publishing server has been authorized (@pxref{Invoking guix
5705 archive}), the daemon may download substitutes from it:
5708 guix-daemon --substitute-urls=http://example.org:8080
5711 As a bonus, @command{guix publish} also serves as a content-addressed
5712 mirror for source files referenced in @code{origin} records
5713 (@pxref{origin Reference}). For instance, assuming @command{guix
5714 publish} is running on @code{example.org}, the following URL returns the
5715 raw @file{hello-2.10.tar.gz} file with the given SHA256 hash
5716 (represented in @code{nix-base32} format, @pxref{Invoking guix hash}):
5719 http://example.org/file/hello-2.10.tar.gz/sha256/0ssi1@dots{}ndq1i
5722 Obviously, these URLs only work for files that are in the store; in
5723 other cases, they return 404 (``Not Found'').
5725 The following options are available:
5728 @item --port=@var{port}
5729 @itemx -p @var{port}
5730 Listen for HTTP requests on @var{port}.
5732 @item --listen=@var{host}
5733 Listen on the network interface for @var{host}. The default is to
5734 accept connections from any interface.
5736 @item --user=@var{user}
5737 @itemx -u @var{user}
5738 Change privileges to @var{user} as soon as possible---i.e., once the
5739 server socket is open and the signing key has been read.
5741 @item --compression[=@var{level}]
5742 @itemx -C [@var{level}]
5743 Compress data using the given @var{level}. When @var{level} is zero,
5744 disable compression. The range 1 to 9 corresponds to different gzip
5745 compression levels: 1 is the fastest, and 9 is the best (CPU-intensive).
5748 Compression occurs on the fly and the compressed streams are not
5749 cached. Thus, to reduce load on the machine that runs @command{guix
5750 publish}, it may be a good idea to choose a low compression level, or to
5751 run @command{guix publish} behind a caching proxy.
5753 @item --ttl=@var{ttl}
5754 Produce @code{Cache-Control} HTTP headers that advertise a time-to-live
5755 (TTL) of @var{ttl}. @var{ttl} must denote a duration: @code{5d} means 5
5756 days, @code{1m} means 1 month, and so on.
5758 This allows the user's Guix to keep substitute information in cache for
5759 @var{ttl}. However, note that @code{guix publish} does not itself
5760 guarantee that the store items it provides will indeed remain available
5761 for as long as @var{ttl}.
5763 @item --repl[=@var{port}]
5764 @itemx -r [@var{port}]
5765 Spawn a Guile REPL server (@pxref{REPL Servers,,, guile, GNU Guile
5766 Reference Manual}) on @var{port} (37146 by default). This is used
5767 primarily for debugging a running @command{guix publish} server.
5770 Enabling @command{guix publish} on a GuixSD system is a one-liner: just
5771 add a call to @code{guix-publish-service} in the @code{services} field
5772 of the @code{operating-system} declaration (@pxref{guix-publish-service,
5773 @code{guix-publish-service}}).
5776 @node Invoking guix challenge
5777 @section Invoking @command{guix challenge}
5779 @cindex reproducible builds
5780 @cindex verifiable builds
5782 Do the binaries provided by this server really correspond to the source
5783 code it claims to build? Is a package build process deterministic?
5784 These are the questions the @command{guix challenge} command attempts to
5787 The former is obviously an important question: Before using a substitute
5788 server (@pxref{Substitutes}), one had better @emph{verify} that it
5789 provides the right binaries, and thus @emph{challenge} it. The latter
5790 is what enables the former: If package builds are deterministic, then
5791 independent builds of the package should yield the exact same result,
5792 bit for bit; if a server provides a binary different from the one
5793 obtained locally, it may be either corrupt or malicious.
5795 We know that the hash that shows up in @file{/gnu/store} file names is
5796 the hash of all the inputs of the process that built the file or
5797 directory---compilers, libraries, build scripts,
5798 etc. (@pxref{Introduction}). Assuming deterministic build processes,
5799 one store file name should map to exactly one build output.
5800 @command{guix challenge} checks whether there is, indeed, a single
5801 mapping by comparing the build outputs of several independent builds of
5802 any given store item.
5804 The command output looks like this:
5807 $ guix challenge --substitute-urls="https://hydra.gnu.org https://guix.example.org"
5808 updating list of substitutes from 'https://hydra.gnu.org'... 100.0%
5809 updating list of substitutes from 'https://guix.example.org'... 100.0%
5810 /gnu/store/@dots{}-openssl-1.0.2d contents differ:
5811 local hash: 0725l22r5jnzazaacncwsvp9kgf42266ayyp814v7djxs7nk963q
5812 https://hydra.gnu.org/nar/@dots{}-openssl-1.0.2d: 0725l22r5jnzazaacncwsvp9kgf42266ayyp814v7djxs7nk963q
5813 https://guix.example.org/nar/@dots{}-openssl-1.0.2d: 1zy4fmaaqcnjrzzajkdn3f5gmjk754b43qkq47llbyak9z0qjyim
5814 /gnu/store/@dots{}-git-2.5.0 contents differ:
5815 local hash: 00p3bmryhjxrhpn2gxs2fy0a15lnip05l97205pgbk5ra395hyha
5816 https://hydra.gnu.org/nar/@dots{}-git-2.5.0: 069nb85bv4d4a6slrwjdy8v1cn4cwspm3kdbmyb81d6zckj3nq9f
5817 https://guix.example.org/nar/@dots{}-git-2.5.0: 0mdqa9w1p6cmli6976v4wi0sw9r4p5prkj7lzfd1877wk11c9c73
5818 /gnu/store/@dots{}-pius-2.1.1 contents differ:
5819 local hash: 0k4v3m9z1zp8xzzizb7d8kjj72f9172xv078sq4wl73vnq9ig3ax
5820 https://hydra.gnu.org/nar/@dots{}-pius-2.1.1: 0k4v3m9z1zp8xzzizb7d8kjj72f9172xv078sq4wl73vnq9ig3ax
5821 https://guix.example.org/nar/@dots{}-pius-2.1.1: 1cy25x1a4fzq5rk0pmvc8xhwyffnqz95h2bpvqsz2mpvlbccy0gs
5825 In this example, @command{guix challenge} first scans the store to
5826 determine the set of locally-built derivations---as opposed to store
5827 items that were downloaded from a substitute server---and then queries
5828 all the substitute servers. It then reports those store items for which
5829 the servers obtained a result different from the local build.
5831 @cindex non-determinism, in package builds
5832 As an example, @code{guix.example.org} always gets a different answer.
5833 Conversely, @code{hydra.gnu.org} agrees with local builds, except in the
5834 case of Git. This might indicate that the build process of Git is
5835 non-deterministic, meaning that its output varies as a function of
5836 various things that Guix does not fully control, in spite of building
5837 packages in isolated environments (@pxref{Features}). Most common
5838 sources of non-determinism include the addition of timestamps in build
5839 results, the inclusion of random numbers, and directory listings sorted
5840 by inode number. See @uref{https://reproducible-builds.org/docs/}, for
5843 To find out what is wrong with this Git binary, we can do something along
5844 these lines (@pxref{Invoking guix archive}):
5847 $ wget -q -O - https://hydra.gnu.org/nar/@dots{}-git-2.5.0 \
5848 | guix archive -x /tmp/git
5849 $ diff -ur --no-dereference /gnu/store/@dots{}-git.2.5.0 /tmp/git
5852 This command shows the difference between the files resulting from the
5853 local build, and the files resulting from the build on
5854 @code{hydra.gnu.org} (@pxref{Overview, Comparing and Merging Files,,
5855 diffutils, Comparing and Merging Files}). The @command{diff} command
5856 works great for text files. When binary files differ, a better option
5857 is @uref{https://diffoscope.org/, Diffoscope}, a tool that helps
5858 visualize differences for all kinds of files.
5860 Once you have done that work, you can tell whether the differences are due
5861 to a non-deterministic build process or to a malicious server. We try
5862 hard to remove sources of non-determinism in packages to make it easier
5863 to verify substitutes, but of course, this is a process that
5864 involves not just Guix, but a large part of the free software community.
5865 In the meantime, @command{guix challenge} is one tool to help address
5868 If you are writing packages for Guix, you are encouraged to check
5869 whether @code{hydra.gnu.org} and other substitute servers obtain the
5870 same build result as you did with:
5873 $ guix challenge @var{package}
5877 where @var{package} is a package specification such as
5878 @code{guile@@2.0} or @code{glibc:debug}.
5880 The general syntax is:
5883 guix challenge @var{options} [@var{packages}@dots{}]
5886 When a difference is found between the hash of a locally-built item and
5887 that of a server-provided substitute, or among substitutes provided by
5888 different servers, the command displays it as in the example above and
5889 its exit code is 2 (other non-zero exit codes denote other kinds of
5892 The one option that matters is:
5896 @item --substitute-urls=@var{urls}
5897 Consider @var{urls} the whitespace-separated list of substitute source
5903 @node Invoking guix container
5904 @section Invoking @command{guix container}
5908 As of version @value{VERSION}, this tool is experimental. The interface
5909 is subject to radical change in the future.
5912 The purpose of @command{guix container} is to manipulate processes
5913 running within an isolated environment, commonly known as a
5914 ``container'', typically created by the @command{guix environment}
5915 (@pxref{Invoking guix environment}) and @command{guix system container}
5916 (@pxref{Invoking guix system}) commands.
5918 The general syntax is:
5921 guix container @var{action} @var{options}@dots{}
5924 @var{action} specifies the operation to perform with a container, and
5925 @var{options} specifies the context-specific arguments for the action.
5927 The following actions are available:
5931 Execute a command within the context of a running container.
5936 guix container exec @var{pid} @var{program} @var{arguments}@dots{}
5939 @var{pid} specifies the process ID of the running container.
5940 @var{program} specifies an executable file name within the root file
5941 system of the container. @var{arguments} are the additional options that
5942 will be passed to @var{program}.
5944 The following command launches an interactive login shell inside a
5945 GuixSD container, started by @command{guix system container}, and whose
5949 guix container exec 9001 /run/current-system/profile/bin/bash --login
5952 Note that the @var{pid} cannot be the parent process of a container. It
5953 must be PID 1 of the container or one of its child processes.
5957 @c *********************************************************************
5958 @node GNU Distribution
5959 @chapter GNU Distribution
5961 @cindex Guix System Distribution
5963 Guix comes with a distribution of the GNU system consisting entirely of
5964 free software@footnote{The term ``free'' here refers to the
5965 @url{http://www.gnu.org/philosophy/free-sw.html,freedom provided to
5966 users of that software}.}. The
5967 distribution can be installed on its own (@pxref{System Installation}),
5968 but it is also possible to install Guix as a package manager on top of
5969 an installed GNU/Linux system (@pxref{Installation}). To distinguish
5970 between the two, we refer to the standalone distribution as the Guix
5971 System Distribution, or GuixSD.
5973 The distribution provides core GNU packages such as GNU libc, GCC, and
5974 Binutils, as well as many GNU and non-GNU applications. The complete
5975 list of available packages can be browsed
5976 @url{http://www.gnu.org/software/guix/packages,on-line} or by
5977 running @command{guix package} (@pxref{Invoking guix package}):
5980 guix package --list-available
5983 Our goal is to provide a practical 100% free software distribution of
5984 Linux-based and other variants of GNU, with a focus on the promotion and
5985 tight integration of GNU components, and an emphasis on programs and
5986 tools that help users exert that freedom.
5988 Packages are currently available on the following platforms:
5993 Intel/AMD @code{x86_64} architecture, Linux-Libre kernel;
5996 Intel 32-bit architecture (IA32), Linux-Libre kernel;
5999 ARMv7-A architecture with hard float, Thumb-2 and NEON,
6000 using the EABI hard-float application binary interface (ABI),
6001 and Linux-Libre kernel.
6003 @item mips64el-linux
6004 little-endian 64-bit MIPS processors, specifically the Loongson series,
6005 n32 ABI, and Linux-Libre kernel.
6009 GuixSD itself is currently only available on @code{i686} and @code{x86_64}.
6012 For information on porting to other architectures or kernels,
6016 * System Installation:: Installing the whole operating system.
6017 * System Configuration:: Configuring the operating system.
6018 * Installing Debugging Files:: Feeding the debugger.
6019 * Security Updates:: Deploying security fixes quickly.
6020 * Package Modules:: Packages from the programmer's viewpoint.
6021 * Packaging Guidelines:: Growing the distribution.
6022 * Bootstrapping:: GNU/Linux built from scratch.
6023 * Porting:: Targeting another platform or kernel.
6026 Building this distribution is a cooperative effort, and you are invited
6027 to join! @xref{Contributing}, for information about how you can help.
6029 @node System Installation
6030 @section System Installation
6032 @cindex Guix System Distribution
6033 This section explains how to install the Guix System Distribution (GuixSD)
6034 on a machine. The Guix package manager can
6035 also be installed on top of a running GNU/Linux system,
6036 @pxref{Installation}.
6040 @c This paragraph is for people reading this from tty2 of the
6041 @c installation image.
6042 You are reading this documentation with an Info reader. For details on
6043 how to use it, hit the @key{RET} key (``return'' or ``enter'') on the
6044 link that follows: @pxref{Top, Info reader,, info-stnd, Stand-alone GNU
6045 Info}. Hit @kbd{l} afterwards to come back here.
6047 Alternately, run @command{info info} in another tty to keep the manual
6053 * Limitations:: What you can expect.
6054 * Hardware Considerations:: Supported hardware.
6055 * USB Stick Installation:: Preparing the installation medium.
6056 * Preparing for Installation:: Networking, partitioning, etc.
6057 * Proceeding with the Installation:: The real thing.
6058 * Installing GuixSD in a VM:: GuixSD playground.
6059 * Building the Installation Image:: How this comes to be.
6063 @subsection Limitations
6065 As of version @value{VERSION}, the Guix System Distribution (GuixSD) is
6066 not production-ready. It may contain bugs and lack important
6067 features. Thus, if you are looking for a stable production system that
6068 respects your freedom as a computer user, a good solution at this point
6069 is to consider @url{http://www.gnu.org/distros/free-distros.html, one of
6070 the more established GNU/Linux distributions}. We hope you can soon switch
6071 to the GuixSD without fear, of course. In the meantime, you can
6072 also keep using your distribution and try out the package manager on top
6073 of it (@pxref{Installation}).
6075 Before you proceed with the installation, be aware of the following
6076 noteworthy limitations applicable to version @value{VERSION}:
6080 The installation process does not include a graphical user interface and
6081 requires familiarity with GNU/Linux (see the following subsections to
6082 get a feel of what that means.)
6085 Support for the Logical Volume Manager (LVM) is missing.
6088 Few system services are currently supported out-of-the-box
6092 More than 3,200 packages are available, but you may
6093 occasionally find that a useful package is missing.
6096 GNOME, Xfce, and Enlightenment are available (@pxref{Desktop Services}),
6097 as well as a number of X11 window managers. However, some graphical
6098 applications may be missing, as well as KDE.
6101 You have been warned! But more than a disclaimer, this is an invitation
6102 to report issues (and success stories!), and to join us in improving it.
6103 @xref{Contributing}, for more info.
6106 @node Hardware Considerations
6107 @subsection Hardware Considerations
6109 @cindex hardware support on GuixSD
6110 GNU@tie{}GuixSD focuses on respecting the user's computing freedom. It
6111 builds around the kernel Linux-libre, which means that only hardware for
6112 which free software drivers and firmware exist is supported. Nowadays,
6113 a wide range of off-the-shelf hardware is supported on
6114 GNU/Linux-libre---from keyboards to graphics cards to scanners and
6115 Ethernet controllers. Unfortunately, there are still areas where
6116 hardware vendors deny users control over their own computing, and such
6117 hardware is not supported on GuixSD.
6119 @cindex WiFi, hardware support
6120 One of the main areas where free drivers or firmware are lacking is WiFi
6121 devices. WiFi devices known to work include those using Atheros chips
6122 (AR9271 and AR7010), which corresponds to the @code{ath9k} Linux-libre
6123 driver, and for which free firmware exists and is available
6124 out-of-the-box on GuixSD, as part of @var{%base-firmware}
6125 (@pxref{operating-system Reference, @code{firmware}}).
6127 @cindex RYF, Respects Your Freedom
6128 The @uref{https://www.fsf.org/, Free Software Foundation} runs
6129 @uref{https://www.fsf.org/ryf, @dfn{Respects Your Freedom}} (RYF), a
6130 certification program for hardware products that respect your freedom
6131 and your privacy and ensure that you have control over your device. We
6132 encourage you to check the list of RYF-certified devices.
6134 Another useful resource is the @uref{https://www.h-node.org/, H-Node}
6135 web site. It contains a catalog of hardware devices with information
6136 about their support in GNU/Linux.
6139 @node USB Stick Installation
6140 @subsection USB Stick Installation
6142 An installation image for USB sticks can be downloaded from
6143 @indicateurl{ftp://alpha.gnu.org/gnu/guix/guixsd-usb-install-@value{VERSION}.@var{system}.xz},
6144 where @var{system} is one of:
6148 for a GNU/Linux system on Intel/AMD-compatible 64-bit CPUs;
6151 for a 32-bit GNU/Linux system on Intel-compatible CPUs.
6154 @c start duplication of authentication part from ``Binary Installation''
6155 Make sure to download the associated @file{.sig} file and to verify the
6156 authenticity of the image against it, along these lines:
6159 $ wget ftp://alpha.gnu.org/gnu/guix/guixsd-usb-install-@value{VERSION}.@var{system}.xz.sig
6160 $ gpg --verify guixsd-usb-install-@value{VERSION}.@var{system}.xz.sig
6163 If that command fails because you do not have the required public key,
6164 then run this command to import it:
6167 $ gpg --keyserver pgp.mit.edu --recv-keys @value{OPENPGP-SIGNING-KEY-ID}
6171 and rerun the @code{gpg --verify} command.
6174 This image contains a single partition with the tools necessary for an
6175 installation. It is meant to be copied @emph{as is} to a large-enough
6178 To copy the image to a USB stick, follow these steps:
6182 Decompress the image using the @command{xz} command:
6185 xz -d guixsd-usb-install-@value{VERSION}.@var{system}.xz
6189 Insert a USB stick of 1@tie{}GiB or more into your machine, and determine
6190 its device name. Assuming that the USB stick is known as @file{/dev/sdX},
6191 copy the image with:
6194 dd if=guixsd-usb-install-@value{VERSION}.x86_64 of=/dev/sdX
6197 Access to @file{/dev/sdX} usually requires root privileges.
6200 Once this is done, you should be able to reboot the system and boot from
6201 the USB stick. The latter usually requires you to get in the BIOS' boot
6202 menu, where you can choose to boot from the USB stick.
6204 @xref{Installing GuixSD in a VM}, if, instead, you would like to install
6205 GuixSD in a virtual machine (VM).
6207 @node Preparing for Installation
6208 @subsection Preparing for Installation
6210 Once you have successfully booted the image on the USB stick, you should
6211 end up with a root prompt. Several console TTYs are configured and can
6212 be used to run commands as root. TTY2 shows this documentation,
6213 browsable using the Info reader commands (@pxref{Top,,, info-stnd,
6214 Stand-alone GNU Info}). The installation system runs the GPM mouse
6215 daemon, which allows you to select text with the left mouse button and
6216 to paste it with the middle button.
6219 Installation requires access to the Internet so that any missing
6220 dependencies of your system configuration can be downloaded. See the
6221 ``Networking'' section below.
6224 The installation system includes many common tools needed for this task.
6225 But it is also a full-blown GuixSD system, which means that you can
6226 install additional packages, should you need it, using @command{guix
6227 package} (@pxref{Invoking guix package}).
6229 @subsubsection Keyboard Layout
6231 @cindex keyboard layout
6232 The installation image uses the US qwerty keyboard layout. If you want
6233 to change it, you can use the @command{loadkeys} command. For example,
6234 the following command selects the Dvorak keyboard layout:
6240 See the files under @file{/run/current-system/profile/share/keymaps} for
6241 a list of available keyboard layouts. Run @command{man loadkeys} for
6244 @subsubsection Networking
6246 Run the following command see what your network interfaces are called:
6253 @dots{} or, using the GNU/Linux-specific @command{ip} command:
6259 @c http://cgit.freedesktop.org/systemd/systemd/tree/src/udev/udev-builtin-net_id.c#n20
6260 Wired interfaces have a name starting with @samp{e}; for example, the
6261 interface corresponding to the first on-board Ethernet controller is
6262 called @samp{eno1}. Wireless interfaces have a name starting with
6263 @samp{w}, like @samp{w1p2s0}.
6266 @item Wired connection
6267 To configure a wired network run the following command, substituting
6268 @var{interface} with the name of the wired interface you want to use.
6271 ifconfig @var{interface} up
6274 @item Wireless connection
6275 To configure wireless networking, you can create a configuration file
6276 for the @command{wpa_supplicant} configuration tool (its location is not
6277 important) using one of the available text editors such as
6281 zile wpa_supplicant.conf
6284 As an example, the following stanza can go to this file and will work
6285 for many wireless networks, provided you give the actual SSID and
6286 passphrase for the network you are connecting to:
6290 ssid="@var{my-ssid}"
6292 psk="the network's secret passphrase"
6296 Start the wireless service and run it in the background with the
6297 following command (substitute @var{interface} with the name of the
6298 network interface you want to use):
6301 wpa_supplicant -c wpa_supplicant.conf -i @var{interface} -B
6304 Run @command{man wpa_supplicant} for more information.
6307 At this point, you need to acquire an IP address. On a network where IP
6308 addresses are automatically assigned @i{via} DHCP, you can run:
6311 dhclient -v @var{interface}
6314 Try to ping a server to see if networking is up and running:
6320 Setting up network access is almost always a requirement because the
6321 image does not contain all the software and tools that may be needed.
6323 @subsubsection Disk Partitioning
6325 Unless this has already been done, the next step is to partition, and
6326 then format the target partition(s).
6328 The installation image includes several partitioning tools, including
6329 Parted (@pxref{Overview,,, parted, GNU Parted User Manual}),
6330 @command{fdisk}, and @command{cfdisk}. Run it and set up your disk with
6331 the partition layout you want:
6337 Once you are done partitioning the target hard disk drive, you have to
6338 create a file system on the relevant partition(s)@footnote{Currently
6339 GuixSD pretty much assumes an ext4 file system. In particular, code
6340 that reads partition UUIDs and labels only works with ext4. This will
6341 be fixed in the future.}.
6343 Preferably, assign partitions a label so that you can easily and
6344 reliably refer to them in @code{file-system} declarations (@pxref{File
6345 Systems}). This is typically done using the @code{-L} option of
6346 @command{mkfs.ext4} and related commands. So, assuming the target root
6347 partition lives at @file{/dev/sda1}, a file system with the label
6348 @code{my-root} can be created with:
6351 mkfs.ext4 -L my-root /dev/sda1
6354 @c FIXME: Uncomment this once GRUB fully supports encrypted roots.
6355 @c A typical command sequence may be:
6359 @c @dots{} Create partitions etc.@dots{}
6360 @c # cryptsetup luksFormat /dev/sdX1
6361 @c # cryptsetup open --type luks /dev/sdX1 my-partition
6362 @c # mkfs.ext4 -L my-root /dev/mapper/my-partition
6365 In addition to e2fsprogs, the suite of tools to manipulate
6366 ext2/ext3/ext4 file systems, the installation image includes
6367 Cryptsetup/LUKS for disk encryption.
6369 Once that is done, mount the target root partition under @file{/mnt}
6370 with a command like (again, assuming @file{/dev/sda1} is the root
6374 mount /dev/sda1 /mnt
6377 Finally, if you plan to use one or more swap partitions (@pxref{Memory
6378 Concepts, swap space,, libc, The GNU C Library Reference Manual}), make
6379 sure to initialize them with @command{mkswap}. Assuming you have one
6380 swap partition on @file{/dev/sda2}, you would run:
6386 @node Proceeding with the Installation
6387 @subsection Proceeding with the Installation
6389 With the target partitions ready and the target root mounted on
6390 @file{/mnt}, we're ready to go. First, run:
6393 herd start cow-store /mnt
6396 This makes @file{/gnu/store} copy-on-write, such that packages added to it
6397 during the installation phase are written to the target disk on @file{/mnt}
6398 rather than kept in memory. This is necessary because the first phase of
6399 the @command{guix system init} command (see below) entails downloads or
6400 builds to @file{/gnu/store} which, initially, is an in-memory file system.
6402 Next, you have to edit a file and
6403 provide the declaration of the operating system to be installed. To
6404 that end, the installation system comes with three text editors: GNU nano
6405 (@pxref{Top,,, nano, GNU nano Manual}), GNU Zile (an Emacs clone), and
6406 nvi (a clone of the original BSD @command{vi} editor).
6407 We strongly recommend storing that file on the target root file system, say,
6408 as @file{/mnt/etc/config.scm}. Failing to do that, you will have lost your
6409 configuration file once you have rebooted into the newly-installed system.
6411 @xref{Using the Configuration System}, for an overview of the
6412 configuration file. The example configurations discussed in that
6413 section are available under @file{/etc/configuration} in the
6414 installation image. Thus, to get started with a system configuration
6415 providing a graphical display server (a ``desktop'' system), you can run
6416 something along these lines:
6420 # cp /etc/configuration/desktop.scm /mnt/etc/config.scm
6421 # zile /mnt/etc/config.scm
6424 You should pay attention to what your configuration file contains, and
6429 Make sure the @code{grub-configuration} form refers to the device you
6430 want to install GRUB on.
6433 Be sure that your partition labels match the value of their respective
6434 @code{device} fields in your @code{file-system} configuration, assuming
6435 your @code{file-system} configuration sets the value of @code{title} to
6439 Once you are done preparing the configuration file, the new system must
6440 be initialized (remember that the target root file system is mounted
6444 guix system init /mnt/etc/config.scm /mnt
6448 This copies all the necessary files and installs GRUB on
6449 @file{/dev/sdX}, unless you pass the @option{--no-grub} option. For
6450 more information, @pxref{Invoking guix system}. This command may trigger
6451 downloads or builds of missing packages, which can take some time.
6453 Once that command has completed---and hopefully succeeded!---you can run
6454 @command{reboot} and boot into the new system. The @code{root} password
6455 in the new system is initially empty; other users' passwords need to be
6456 initialized by running the @command{passwd} command as @code{root},
6457 unless your configuration specifies otherwise
6458 (@pxref{user-account-password, user account passwords}).
6460 Join us on @code{#guix} on the Freenode IRC network or on
6461 @file{guix-devel@@gnu.org} to share your experience---good or not so
6464 @node Installing GuixSD in a VM
6465 @subsection Installing GuixSD in a Virtual Machine
6467 @cindex virtual machine, GuixSD installation
6468 If you'd like to install GuixSD in a virtual machine (VM) rather than on
6469 your beloved machine, this section is for you.
6471 To boot a @uref{http://qemu.org/,QEMU} VM for installing GuixSD in a
6472 disk image, follow these steps:
6476 First, retrieve the GuixSD installation image as described previously
6477 (@pxref{USB Stick Installation}).
6480 Create a disk image that will hold the installed system. To make a
6481 qcow2-formatted disk image, use the @command{qemu-img} command:
6484 qemu-img create -f qcow2 guixsd.img 5G
6487 This will create a 5GB file.
6490 Boot the USB installation image in an VM:
6493 qemu-system-x86_64 -m 1024 -smp 1 \
6494 -net default -net nic,model=virtio -boot menu=on \
6495 -drive file=guixsd.img \
6496 -drive file=guixsd-usb-install-@value{VERSION}.@var{system}
6499 In the VM console, quickly press the @kbd{F12} key to enter the boot
6500 menu. Then press the @kbd{2} key and the @kbd{RET} key to validate your
6504 You're now root in the VM, proceed with the installation process.
6505 @xref{Preparing for Installation}, and follow the instructions.
6508 Once installation is complete, you can boot the system that's on your
6509 @file{guixsd.img} image. @xref{Running GuixSD in a VM}, for how to do
6512 @node Building the Installation Image
6513 @subsection Building the Installation Image
6515 The installation image described above was built using the @command{guix
6516 system} command, specifically:
6518 @c FIXME: 1G is too much; see <http://bugs.gnu.org/23077>.
6520 guix system disk-image --image-size=1G gnu/system/install.scm
6523 Have a look at @file{gnu/system/install.scm} in the source tree,
6524 and see also @ref{Invoking guix system} for more information
6525 about the installation image.
6527 @node System Configuration
6528 @section System Configuration
6530 @cindex system configuration
6531 The Guix System Distribution supports a consistent whole-system configuration
6532 mechanism. By that we mean that all aspects of the global system
6533 configuration---such as the available system services, timezone and
6534 locale settings, user accounts---are declared in a single place. Such
6535 a @dfn{system configuration} can be @dfn{instantiated}---i.e., effected.
6537 One of the advantages of putting all the system configuration under the
6538 control of Guix is that it supports transactional system upgrades, and
6539 makes it possible to roll back to a previous system instantiation,
6540 should something go wrong with the new one (@pxref{Features}). Another
6541 advantage is that it makes it easy to replicate the exact same configuration
6542 across different machines, or at different points in time, without
6543 having to resort to additional administration tools layered on top of
6544 the own tools of the system.
6545 @c Yes, we're talking of Puppet, Chef, & co. here. ↑
6547 This section describes this mechanism. First we focus on the system
6548 administrator's viewpoint---explaining how the system is configured and
6549 instantiated. Then we show how this mechanism can be extended, for
6550 instance to support new system services.
6553 * Using the Configuration System:: Customizing your GNU system.
6554 * operating-system Reference:: Detail of operating-system declarations.
6555 * File Systems:: Configuring file system mounts.
6556 * Mapped Devices:: Block device extra processing.
6557 * User Accounts:: Specifying user accounts.
6558 * Locales:: Language and cultural convention settings.
6559 * Services:: Specifying system services.
6560 * Setuid Programs:: Programs running with root privileges.
6561 * X.509 Certificates:: Authenticating HTTPS servers.
6562 * Name Service Switch:: Configuring libc's name service switch.
6563 * Initial RAM Disk:: Linux-Libre bootstrapping.
6564 * GRUB Configuration:: Configuring the boot loader.
6565 * Invoking guix system:: Instantiating a system configuration.
6566 * Running GuixSD in a VM:: How to run GuixSD in a virtual machine.
6567 * Defining Services:: Adding new service definitions.
6570 @node Using the Configuration System
6571 @subsection Using the Configuration System
6573 The operating system is configured by providing an
6574 @code{operating-system} declaration in a file that can then be passed to
6575 the @command{guix system} command (@pxref{Invoking guix system}). A
6576 simple setup, with the default system services, the default Linux-Libre
6577 kernel, initial RAM disk, and boot loader looks like this:
6579 @findex operating-system
6581 @include os-config-bare-bones.texi
6584 This example should be self-describing. Some of the fields defined
6585 above, such as @code{host-name} and @code{bootloader}, are mandatory.
6586 Others, such as @code{packages} and @code{services}, can be omitted, in
6587 which case they get a default value.
6589 Below we discuss the effect of some of the most important fields
6590 (@pxref{operating-system Reference}, for details about all the available
6591 fields), and how to @dfn{instantiate} the operating system using
6592 @command{guix system}.
6594 @unnumberedsubsubsec Globally-Visible Packages
6596 @vindex %base-packages
6597 The @code{packages} field lists packages that will be globally visible
6598 on the system, for all user accounts---i.e., in every user's @code{PATH}
6599 environment variable---in addition to the per-user profiles
6600 (@pxref{Invoking guix package}). The @var{%base-packages} variable
6601 provides all the tools one would expect for basic user and administrator
6602 tasks---including the GNU Core Utilities, the GNU Networking Utilities,
6603 the GNU Zile lightweight text editor, @command{find}, @command{grep},
6604 etc. The example above adds tcpdump to those, taken from the @code{(gnu
6605 packages admin)} module (@pxref{Package Modules}).
6607 @findex specification->package
6608 Referring to packages by variable name, like @var{tcpdump} above, has
6609 the advantage of being unambiguous; it also allows typos and such to be
6610 diagnosed right away as ``unbound variables''. The downside is that one
6611 needs to know which module defines which package, and to augment the
6612 @code{use-package-modules} line accordingly. To avoid that, one can use
6613 the @code{specification->package} procedure of the @code{(gnu packages)}
6614 module, which returns the best package for a given name or name and
6618 (use-modules (gnu packages))
6622 (packages (append (map specification->package
6623 '("tcpdump" "htop" "gnupg@@2.0"))
6627 @unnumberedsubsubsec System Services
6629 @vindex %base-services
6630 The @code{services} field lists @dfn{system services} to be made
6631 available when the system starts (@pxref{Services}).
6632 The @code{operating-system} declaration above specifies that, in
6633 addition to the basic services, we want the @command{lshd} secure shell
6634 daemon listening on port 2222 (@pxref{Networking Services,
6635 @code{lsh-service}}). Under the hood,
6636 @code{lsh-service} arranges so that @code{lshd} is started with the
6637 right command-line options, possibly with supporting configuration files
6638 generated as needed (@pxref{Defining Services}).
6640 @cindex customization, of services
6641 @findex modify-services
6642 Occasionally, instead of using the base services as is, you will want to
6643 customize them. To do this, use @code{modify-services} (@pxref{Service
6644 Reference, @code{modify-services}}) to modify the list.
6646 For example, suppose you want to modify @code{guix-daemon} and Mingetty
6647 (the console log-in) in the @var{%base-services} list (@pxref{Base
6648 Services, @code{%base-services}}). To do that, you can write the
6649 following in your operating system declaration:
6652 (define %my-services
6653 ;; My very own list of services.
6654 (modify-services %base-services
6655 (guix-service-type config =>
6658 (use-substitutes? #f)
6659 (extra-options '("--gc-keep-derivations"))))
6660 (mingetty-service-type config =>
6661 (mingetty-configuration
6663 (motd (plain-file "motd" "Howdy!"))))))
6667 (services %my-services))
6670 This changes the configuration---i.e., the service parameters---of the
6671 @code{guix-service-type} instance, and that of all the
6672 @code{mingetty-service-type} instances in the @var{%base-services} list.
6673 Observe how this is accomplished: first, we arrange for the original
6674 configuration to be bound to the identifier @code{config} in the
6675 @var{body}, and then we write the @var{body} so that it evaluates to the
6676 desired configuration. In particular, notice how we use @code{inherit}
6677 to create a new configuration which has the same values as the old
6678 configuration, but with a few modifications.
6680 The configuration for a typical ``desktop'' usage, with the X11 display
6681 server, GNOME and Xfce (users can choose which of these desktop
6682 environments to use at the log-in screen by pressing @kbd{F1}), network
6683 management, power management, and more, would look like this:
6686 @include os-config-desktop.texi
6689 A graphical environment with a choice of lightweight window managers
6690 instead of full-blown desktop environments would look like this:
6693 @include os-config-lightweight-desktop.texi
6696 @xref{Desktop Services}, for the exact list of services provided by
6697 @var{%desktop-services}. @xref{X.509 Certificates}, for background
6698 information about the @code{nss-certs} package that is used here.
6700 Again, @var{%desktop-services} is just a list of service objects. If
6701 you want to remove services from there, you can do so using the
6702 procedures for list filtering (@pxref{SRFI-1 Filtering and
6703 Partitioning,,, guile, GNU Guile Reference Manual}). For instance, the
6704 following expression returns a list that contains all the services in
6705 @var{%desktop-services} minus the Avahi service:
6708 (remove (lambda (service)
6709 (eq? (service-kind service) avahi-service-type))
6713 @unnumberedsubsubsec Instantiating the System
6715 Assuming the @code{operating-system} declaration
6716 is stored in the @file{my-system-config.scm}
6717 file, the @command{guix system reconfigure my-system-config.scm} command
6718 instantiates that configuration, and makes it the default GRUB boot
6719 entry (@pxref{Invoking guix system}).
6721 The normal way to change the system configuration is by updating this
6722 file and re-running @command{guix system reconfigure}. One should never
6723 have to touch files in @command{/etc} or to run commands that modify the
6724 system state such as @command{useradd} or @command{grub-install}. In
6725 fact, you must avoid that since that would not only void your warranty
6726 but also prevent you from rolling back to previous versions of your
6727 system, should you ever need to.
6729 @cindex roll-back, of the operating system
6730 Speaking of roll-back, each time you run @command{guix system
6731 reconfigure}, a new @dfn{generation} of the system is created---without
6732 modifying or deleting previous generations. Old system generations get
6733 an entry in the GRUB boot menu, allowing you to boot them in case
6734 something went wrong with the latest generation. Reassuring, no? The
6735 @command{guix system list-generations} command lists the system
6736 generations available on disk.
6738 @unnumberedsubsubsec The Programming Interface
6740 At the Scheme level, the bulk of an @code{operating-system} declaration
6741 is instantiated with the following monadic procedure (@pxref{The Store
6744 @deffn {Monadic Procedure} operating-system-derivation os
6745 Return a derivation that builds @var{os}, an @code{operating-system}
6746 object (@pxref{Derivations}).
6748 The output of the derivation is a single directory that refers to all
6749 the packages, configuration files, and other supporting files needed to
6750 instantiate @var{os}.
6753 This procedure is provided by the @code{(gnu system)} module. Along
6754 with @code{(gnu services)} (@pxref{Services}), this module contains the
6755 guts of GuixSD. Make sure to visit it!
6758 @node operating-system Reference
6759 @subsection @code{operating-system} Reference
6761 This section summarizes all the options available in
6762 @code{operating-system} declarations (@pxref{Using the Configuration
6765 @deftp {Data Type} operating-system
6766 This is the data type representing an operating system configuration.
6767 By that, we mean all the global system configuration, not per-user
6768 configuration (@pxref{Using the Configuration System}).
6771 @item @code{kernel} (default: @var{linux-libre})
6772 The package object of the operating system kernel to use@footnote{Currently
6773 only the Linux-libre kernel is supported. In the future, it will be
6774 possible to use the GNU@tie{}Hurd.}.
6776 @item @code{kernel-arguments} (default: @code{'()})
6777 List of strings or gexps representing additional arguments to pass on
6778 the command-line of the kernel---e.g., @code{("console=ttyS0")}.
6780 @item @code{bootloader}
6781 The system bootloader configuration object. @xref{GRUB Configuration}.
6783 @item @code{initrd} (default: @code{base-initrd})
6784 A two-argument monadic procedure that returns an initial RAM disk for
6785 the Linux kernel. @xref{Initial RAM Disk}.
6787 @item @code{firmware} (default: @var{%base-firmware})
6789 List of firmware packages loadable by the operating system kernel.
6791 The default includes firmware needed for Atheros-based WiFi devices
6792 (Linux-libre module @code{ath9k}). @xref{Hardware Considerations}, for
6793 more info on supported hardware.
6795 @item @code{host-name}
6798 @item @code{hosts-file}
6800 A file-like object (@pxref{G-Expressions, file-like objects}) for use as
6801 @file{/etc/hosts} (@pxref{Host Names,,, libc, The GNU C Library
6802 Reference Manual}). The default is a file with entries for
6803 @code{localhost} and @var{host-name}.
6805 @item @code{mapped-devices} (default: @code{'()})
6806 A list of mapped devices. @xref{Mapped Devices}.
6808 @item @code{file-systems}
6809 A list of file systems. @xref{File Systems}.
6811 @item @code{swap-devices} (default: @code{'()})
6812 @cindex swap devices
6813 A list of strings identifying devices to be used for ``swap space''
6814 (@pxref{Memory Concepts,,, libc, The GNU C Library Reference Manual}).
6815 For example, @code{'("/dev/sda3")}.
6817 @item @code{users} (default: @code{%base-user-accounts})
6818 @itemx @code{groups} (default: @var{%base-groups})
6819 List of user accounts and groups. @xref{User Accounts}.
6821 @item @code{skeletons} (default: @code{(default-skeletons)})
6822 A list target file name/file-like object tuples (@pxref{G-Expressions,
6823 file-like objects}). These are the skeleton files that will be added to
6824 the home directory of newly-created user accounts.
6826 For instance, a valid value may look like this:
6829 `((".bashrc" ,(plain-file "bashrc" "echo Hello\n"))
6830 (".guile" ,(plain-file "guile"
6831 "(use-modules (ice-9 readline))
6832 (activate-readline)")))
6835 @item @code{issue} (default: @var{%default-issue})
6836 A string denoting the contents of the @file{/etc/issue} file, which is
6837 displayed when users log in on a text console.
6839 @item @code{packages} (default: @var{%base-packages})
6840 The set of packages installed in the global profile, which is accessible
6841 at @file{/run/current-system/profile}.
6843 The default set includes core utilities and it is good practice to
6844 install non-core utilities in user profiles (@pxref{Invoking guix
6847 @item @code{timezone}
6848 A timezone identifying string---e.g., @code{"Europe/Paris"}.
6850 You can run the @command{tzselect} command to find out which timezone
6851 string corresponds to your region. Choosing an invalid timezone name
6852 causes @command{guix system} to fail.
6854 @item @code{locale} (default: @code{"en_US.utf8"})
6855 The name of the default locale (@pxref{Locale Names,,, libc, The GNU C
6856 Library Reference Manual}). @xref{Locales}, for more information.
6858 @item @code{locale-definitions} (default: @var{%default-locale-definitions})
6859 The list of locale definitions to be compiled and that may be used at
6860 run time. @xref{Locales}.
6862 @item @code{locale-libcs} (default: @code{(list @var{glibc})})
6863 The list of GNU@tie{}libc packages whose locale data and tools are used
6864 to build the locale definitions. @xref{Locales}, for compatibility
6865 considerations that justify this option.
6867 @item @code{name-service-switch} (default: @var{%default-nss})
6868 Configuration of the libc name service switch (NSS)---a
6869 @code{<name-service-switch>} object. @xref{Name Service Switch}, for
6872 @item @code{services} (default: @var{%base-services})
6873 A list of service objects denoting system services. @xref{Services}.
6875 @item @code{pam-services} (default: @code{(base-pam-services)})
6877 @cindex pluggable authentication modules
6878 Linux @dfn{pluggable authentication module} (PAM) services.
6879 @c FIXME: Add xref to PAM services section.
6881 @item @code{setuid-programs} (default: @var{%setuid-programs})
6882 List of string-valued G-expressions denoting setuid programs.
6883 @xref{Setuid Programs}.
6885 @item @code{sudoers-file} (default: @var{%sudoers-specification})
6886 @cindex sudoers file
6887 The contents of the @file{/etc/sudoers} file as a file-like object
6888 (@pxref{G-Expressions, @code{local-file} and @code{plain-file}}).
6890 This file specifies which users can use the @command{sudo} command, what
6891 they are allowed to do, and what privileges they may gain. The default
6892 is that only @code{root} and members of the @code{wheel} group may use
6899 @subsection File Systems
6901 The list of file systems to be mounted is specified in the
6902 @code{file-systems} field of the operating system declaration
6903 (@pxref{Using the Configuration System}). Each file system is declared
6904 using the @code{file-system} form, like this:
6908 (mount-point "/home")
6909 (device "/dev/sda3")
6913 As usual, some of the fields are mandatory---those shown in the example
6914 above---while others can be omitted. These are described below.
6916 @deftp {Data Type} file-system
6917 Objects of this type represent file systems to be mounted. They
6918 contain the following members:
6922 This is a string specifying the type of the file system---e.g.,
6925 @item @code{mount-point}
6926 This designates the place where the file system is to be mounted.
6929 This names the ``source'' of the file system. By default it is the name
6930 of a node under @file{/dev}, but its meaning depends on the @code{title}
6931 field described below.
6933 @item @code{title} (default: @code{'device})
6934 This is a symbol that specifies how the @code{device} field is to be
6937 When it is the symbol @code{device}, then the @code{device} field is
6938 interpreted as a file name; when it is @code{label}, then @code{device}
6939 is interpreted as a partition label name; when it is @code{uuid},
6940 @code{device} is interpreted as a partition unique identifier (UUID).
6942 UUIDs may be converted from their string representation (as shown by the
6943 @command{tune2fs -l} command) using the @code{uuid} form@footnote{The
6944 @code{uuid} form expects 16-byte UUIDs as defined in
6945 @uref{https://tools.ietf.org/html/rfc4122, RFC@tie{}4122}. This is the
6946 form of UUID used by the ext2 family of file systems and others, but it
6947 is different from ``UUIDs'' found in FAT file systems, for instance.},
6952 (mount-point "/home")
6955 (device (uuid "4dab5feb-d176-45de-b287-9b0a6e4c01cb")))
6958 The @code{label} and @code{uuid} options offer a way to refer to disk
6959 partitions without having to hard-code their actual device
6960 name@footnote{Note that, while it is tempting to use
6961 @file{/dev/disk/by-uuid} and similar device names to achieve the same
6962 result, this is not recommended: These special device nodes are created
6963 by the udev daemon and may be unavailable at the time the device is
6966 However, when the source of a file system is a mapped device (@pxref{Mapped
6967 Devices}), its @code{device} field @emph{must} refer to the mapped
6968 device name---e.g., @file{/dev/mapper/root-partition}---and consequently
6969 @code{title} must be set to @code{'device}. This is required so that
6970 the system knows that mounting the file system depends on having the
6971 corresponding device mapping established.
6973 @item @code{flags} (default: @code{'()})
6974 This is a list of symbols denoting mount flags. Recognized flags
6975 include @code{read-only}, @code{bind-mount}, @code{no-dev} (disallow
6976 access to special files), @code{no-suid} (ignore setuid and setgid
6977 bits), and @code{no-exec} (disallow program execution.)
6979 @item @code{options} (default: @code{#f})
6980 This is either @code{#f}, or a string denoting mount options.
6982 @item @code{mount?} (default: @code{#t})
6983 This value indicates whether to automatically mount the file system when
6984 the system is brought up. When set to @code{#f}, the file system gets
6985 an entry in @file{/etc/fstab} (read by the @command{mount} command) but
6986 is not automatically mounted.
6988 @item @code{needed-for-boot?} (default: @code{#f})
6989 This Boolean value indicates whether the file system is needed when
6990 booting. If that is true, then the file system is mounted when the
6991 initial RAM disk (initrd) is loaded. This is always the case, for
6992 instance, for the root file system.
6994 @item @code{check?} (default: @code{#t})
6995 This Boolean indicates whether the file system needs to be checked for
6996 errors before being mounted.
6998 @item @code{create-mount-point?} (default: @code{#f})
6999 When true, the mount point is created if it does not exist yet.
7001 @item @code{dependencies} (default: @code{'()})
7002 This is a list of @code{<file-system>} objects representing file systems
7003 that must be mounted before (and unmounted after) this one.
7005 As an example, consider a hierarchy of mounts: @file{/sys/fs/cgroup} is
7006 a dependency of @file{/sys/fs/cgroup/cpu} and
7007 @file{/sys/fs/cgroup/memory}.
7012 The @code{(gnu system file-systems)} exports the following useful
7015 @defvr {Scheme Variable} %base-file-systems
7016 These are essential file systems that are required on normal systems,
7017 such as @var{%pseudo-terminal-file-system} and @var{%immutable-store} (see
7018 below.) Operating system declarations should always contain at least
7022 @defvr {Scheme Variable} %pseudo-terminal-file-system
7023 This is the file system to be mounted as @file{/dev/pts}. It supports
7024 @dfn{pseudo-terminals} created @i{via} @code{openpty} and similar
7025 functions (@pxref{Pseudo-Terminals,,, libc, The GNU C Library Reference
7026 Manual}). Pseudo-terminals are used by terminal emulators such as
7030 @defvr {Scheme Variable} %shared-memory-file-system
7031 This file system is mounted as @file{/dev/shm} and is used to support
7032 memory sharing across processes (@pxref{Memory-mapped I/O,
7033 @code{shm_open},, libc, The GNU C Library Reference Manual}).
7036 @defvr {Scheme Variable} %immutable-store
7037 This file system performs a read-only ``bind mount'' of
7038 @file{/gnu/store}, making it read-only for all the users including
7039 @code{root}. This prevents against accidental modification by software
7040 running as @code{root} or by system administrators.
7042 The daemon itself is still able to write to the store: it remounts it
7043 read-write in its own ``name space.''
7046 @defvr {Scheme Variable} %binary-format-file-system
7047 The @code{binfmt_misc} file system, which allows handling of arbitrary
7048 executable file types to be delegated to user space. This requires the
7049 @code{binfmt.ko} kernel module to be loaded.
7052 @defvr {Scheme Variable} %fuse-control-file-system
7053 The @code{fusectl} file system, which allows unprivileged users to mount
7054 and unmount user-space FUSE file systems. This requires the
7055 @code{fuse.ko} kernel module to be loaded.
7058 @node Mapped Devices
7059 @subsection Mapped Devices
7061 @cindex device mapping
7062 @cindex mapped devices
7063 The Linux kernel has a notion of @dfn{device mapping}: a block device,
7064 such as a hard disk partition, can be @dfn{mapped} into another device,
7065 usually in @code{/dev/mapper/},
7066 with additional processing over the data that flows through
7067 it@footnote{Note that the GNU@tie{}Hurd makes no difference between the
7068 concept of a ``mapped device'' and that of a file system: both boil down
7069 to @emph{translating} input/output operations made on a file to
7070 operations on its backing store. Thus, the Hurd implements mapped
7071 devices, like file systems, using the generic @dfn{translator} mechanism
7072 (@pxref{Translators,,, hurd, The GNU Hurd Reference Manual}).}. A
7073 typical example is encryption device mapping: all writes to the mapped
7074 device are encrypted, and all reads are deciphered, transparently.
7075 Guix extends this notion by considering any device or set of devices that
7076 are @dfn{transformed} in some way to create a new device; for instance,
7077 RAID devices are obtained by @dfn{assembling} several other devices, such
7078 as hard disks or partitions, into a new one that behaves as one partition.
7079 Other examples, not yet implemented, are LVM logical volumes.
7081 Mapped devices are declared using the @code{mapped-device} form,
7082 defined as follows; for examples, see below.
7084 @deftp {Data Type} mapped-device
7085 Objects of this type represent device mappings that will be made when
7086 the system boots up.
7090 This is either a string specifying the name of the block device to be mapped,
7091 such as @code{"/dev/sda3"}, or a list of such strings when several devices
7092 need to be assembled for creating a new one.
7095 This string specifies the name of the resulting mapped device. For
7096 kernel mappers such as encrypted devices of type @code{luks-device-mapping},
7097 specifying @code{"my-partition"} leads to the creation of
7098 the @code{"/dev/mapper/my-partition"} device.
7099 For RAID devices of type @code{raid-device-mapping}, the full device name
7100 such as @code{"/dev/md0"} needs to be given.
7103 This must be a @code{mapped-device-kind} object, which specifies how
7104 @var{source} is mapped to @var{target}.
7108 @defvr {Scheme Variable} luks-device-mapping
7109 This defines LUKS block device encryption using the @command{cryptsetup}
7110 command from the package with the same name. It relies on the
7111 @code{dm-crypt} Linux kernel module.
7114 @defvr {Scheme Variable} raid-device-mapping
7115 This defines a RAID device, which is assembled using the @code{mdadm}
7116 command from the package with the same name. It requires a Linux kernel
7117 module for the appropriate RAID level to be loaded, such as @code{raid456}
7118 for RAID-4, RAID-5 or RAID-6, or @code{raid10} for RAID-10.
7121 @cindex disk encryption
7123 The following example specifies a mapping from @file{/dev/sda3} to
7124 @file{/dev/mapper/home} using LUKS---the
7125 @url{http://code.google.com/p/cryptsetup,Linux Unified Key Setup}, a
7126 standard mechanism for disk encryption.
7127 The @file{/dev/mapper/home}
7128 device can then be used as the @code{device} of a @code{file-system}
7129 declaration (@pxref{File Systems}).
7133 (source "/dev/sda3")
7135 (type luks-device-mapping))
7138 Alternatively, to become independent of device numbering, one may obtain
7139 the LUKS UUID (@dfn{unique identifier}) of the source device by a
7143 cryptsetup luksUUID /dev/sda3
7146 and use it as follows:
7150 (source (uuid "cb67fc72-0d54-4c88-9d4b-b225f30b0f44"))
7152 (type luks-device-mapping))
7155 A RAID device formed of the partitions @file{/dev/sda1} and @file{/dev/sdb1}
7156 may be declared as follows:
7160 (source (list "/dev/sda1" "/dev/sdb1"))
7162 (type raid-device-mapping))
7165 The @file{/dev/md0} device can then be used as the @code{device} of a
7166 @code{file-system} declaration (@pxref{File Systems}).
7167 Note that the RAID level need not be given; it is chosen during the
7168 initial creation and formatting of the RAID device and is determined
7169 automatically later.
7173 @subsection User Accounts
7175 User accounts and groups are entirely managed through the
7176 @code{operating-system} declaration. They are specified with the
7177 @code{user-account} and @code{user-group} forms:
7183 (supplementary-groups '("wheel" ;allow use of sudo, etc.
7185 "video" ;video devices such as webcams
7186 "cdrom")) ;the good ol' CD-ROM
7187 (comment "Bob's sister")
7188 (home-directory "/home/alice"))
7191 When booting or upon completion of @command{guix system reconfigure},
7192 the system ensures that only the user accounts and groups specified in
7193 the @code{operating-system} declaration exist, and with the specified
7194 properties. Thus, account or group creations or modifications made by
7195 directly invoking commands such as @command{useradd} are lost upon
7196 reconfiguration or reboot. This ensures that the system remains exactly
7199 @deftp {Data Type} user-account
7200 Objects of this type represent user accounts. The following members may
7205 The name of the user account.
7208 This is the name (a string) or identifier (a number) of the user group
7209 this account belongs to.
7211 @item @code{supplementary-groups} (default: @code{'()})
7212 Optionally, this can be defined as a list of group names that this
7215 @item @code{uid} (default: @code{#f})
7216 This is the user ID for this account (a number), or @code{#f}. In the
7217 latter case, a number is automatically chosen by the system when the
7220 @item @code{comment} (default: @code{""})
7221 A comment about the account, such as the account owner's full name.
7223 @item @code{home-directory}
7224 This is the name of the home directory for the account.
7226 @item @code{shell} (default: Bash)
7227 This is a G-expression denoting the file name of a program to be used as
7228 the shell (@pxref{G-Expressions}).
7230 @item @code{system?} (default: @code{#f})
7231 This Boolean value indicates whether the account is a ``system''
7232 account. System accounts are sometimes treated specially; for instance,
7233 graphical login managers do not list them.
7235 @anchor{user-account-password}
7236 @item @code{password} (default: @code{#f})
7237 You would normally leave this field to @code{#f}, initialize user
7238 passwords as @code{root} with the @command{passwd} command, and then let
7239 users change it with @command{passwd}. Passwords set with
7240 @command{passwd} are of course preserved across reboot and
7243 If you @emph{do} want to have a preset password for an account, then
7244 this field must contain the encrypted password, as a string.
7245 @xref{crypt,,, libc, The GNU C Library Reference Manual}, for more information
7246 on password encryption, and @ref{Encryption,,, guile, GNU Guile Reference
7247 Manual}, for information on Guile's @code{crypt} procedure.
7252 User group declarations are even simpler:
7255 (user-group (name "students"))
7258 @deftp {Data Type} user-group
7259 This type is for, well, user groups. There are just a few fields:
7263 The name of the group.
7265 @item @code{id} (default: @code{#f})
7266 The group identifier (a number). If @code{#f}, a new number is
7267 automatically allocated when the group is created.
7269 @item @code{system?} (default: @code{#f})
7270 This Boolean value indicates whether the group is a ``system'' group.
7271 System groups have low numerical IDs.
7273 @item @code{password} (default: @code{#f})
7274 What, user groups can have a password? Well, apparently yes. Unless
7275 @code{#f}, this field specifies the password of the group.
7280 For convenience, a variable lists all the basic user groups one may
7283 @defvr {Scheme Variable} %base-groups
7284 This is the list of basic user groups that users and/or packages expect
7285 to be present on the system. This includes groups such as ``root'',
7286 ``wheel'', and ``users'', as well as groups used to control access to
7287 specific devices such as ``audio'', ``disk'', and ``cdrom''.
7290 @defvr {Scheme Variable} %base-user-accounts
7291 This is the list of basic system accounts that programs may expect to
7292 find on a GNU/Linux system, such as the ``nobody'' account.
7294 Note that the ``root'' account is not included here. It is a
7295 special-case and is automatically added whether or not it is specified.
7302 A @dfn{locale} defines cultural conventions for a particular language
7303 and region of the world (@pxref{Locales,,, libc, The GNU C Library
7304 Reference Manual}). Each locale has a name that typically has the form
7305 @code{@var{language}_@var{territory}.@var{codeset}}---e.g.,
7306 @code{fr_LU.utf8} designates the locale for the French language, with
7307 cultural conventions from Luxembourg, and using the UTF-8 encoding.
7309 @cindex locale definition
7310 Usually, you will want to specify the default locale for the machine
7311 using the @code{locale} field of the @code{operating-system} declaration
7312 (@pxref{operating-system Reference, @code{locale}}).
7314 The selected locale is automatically added to the @dfn{locale
7315 definitions} known to the system if needed, with its codeset inferred
7316 from its name---e.g., @code{bo_CN.utf8} will be assumed to use the
7317 @code{UTF-8} codeset. Additional locale definitions can be specified in
7318 the @code{locale-definitions} slot of @code{operating-system}---this is
7319 useful, for instance, if the codeset could not be inferred from the
7320 locale name. The default set of locale definitions includes some widely
7321 used locales, but not all the available locales, in order to save space.
7323 For instance, to add the North Frisian locale for Germany, the value of
7327 (cons (locale-definition
7328 (name "fy_DE.utf8") (source "fy_DE"))
7329 %default-locale-definitions)
7332 Likewise, to save space, one might want @code{locale-definitions} to
7333 list only the locales that are actually used, as in:
7336 (list (locale-definition
7337 (name "ja_JP.eucjp") (source "ja_JP")
7338 (charset "EUC-JP")))
7342 The compiled locale definitions are available at
7343 @file{/run/current-system/locale/X.Y}, where @code{X.Y} is the libc
7344 version, which is the default location where the GNU@tie{}libc provided
7345 by Guix looks for locale data. This can be overridden using the
7346 @code{LOCPATH} environment variable (@pxref{locales-and-locpath,
7347 @code{LOCPATH} and locale packages}).
7349 The @code{locale-definition} form is provided by the @code{(gnu system
7350 locale)} module. Details are given below.
7352 @deftp {Data Type} locale-definition
7353 This is the data type of a locale definition.
7358 The name of the locale. @xref{Locale Names,,, libc, The GNU C Library
7359 Reference Manual}, for more information on locale names.
7362 The name of the source for that locale. This is typically the
7363 @code{@var{language}_@var{territory}} part of the locale name.
7365 @item @code{charset} (default: @code{"UTF-8"})
7366 The ``character set'' or ``code set'' for that locale,
7367 @uref{http://www.iana.org/assignments/character-sets, as defined by
7373 @defvr {Scheme Variable} %default-locale-definitions
7374 A list of commonly used UTF-8 locales, used as the default
7375 value of the @code{locale-definitions} field of @code{operating-system}
7379 @cindex normalized codeset in locale names
7380 These locale definitions use the @dfn{normalized codeset} for the part
7381 that follows the dot in the name (@pxref{Using gettextized software,
7382 normalized codeset,, libc, The GNU C Library Reference Manual}). So for
7383 instance it has @code{uk_UA.utf8} but @emph{not}, say,
7387 @subsubsection Locale Data Compatibility Considerations
7389 @cindex incompatibility, of locale data
7390 @code{operating-system} declarations provide a @code{locale-libcs} field
7391 to specify the GNU@tie{}libc packages that are used to compile locale
7392 declarations (@pxref{operating-system Reference}). ``Why would I
7393 care?'', you may ask. Well, it turns out that the binary format of
7394 locale data is occasionally incompatible from one libc version to
7397 @c See <https://sourceware.org/ml/libc-alpha/2015-09/msg00575.html>
7398 @c and <https://lists.gnu.org/archive/html/guix-devel/2015-08/msg00737.html>.
7399 For instance, a program linked against libc version 2.21 is unable to
7400 read locale data produced with libc 2.22; worse, that program
7401 @emph{aborts} instead of simply ignoring the incompatible locale
7402 data@footnote{Versions 2.23 and later of GNU@tie{}libc will simply skip
7403 the incompatible locale data, which is already an improvement.}.
7404 Similarly, a program linked against libc 2.22 can read most, but not
7405 all, of the locale data from libc 2.21 (specifically, @code{LC_COLLATE}
7406 data is incompatible); thus calls to @code{setlocale} may fail, but
7407 programs will not abort.
7409 The ``problem'' in GuixSD is that users have a lot of freedom: They can
7410 choose whether and when to upgrade software in their profiles, and might
7411 be using a libc version different from the one the system administrator
7412 used to build the system-wide locale data.
7414 Fortunately, unprivileged users can also install their own locale data
7415 and define @var{GUIX_LOCPATH} accordingly (@pxref{locales-and-locpath,
7416 @code{GUIX_LOCPATH} and locale packages}).
7418 Still, it is best if the system-wide locale data at
7419 @file{/run/current-system/locale} is built for all the libc versions
7420 actually in use on the system, so that all the programs can access
7421 it---this is especially crucial on a multi-user system. To do that, the
7422 administrator can specify several libc packages in the
7423 @code{locale-libcs} field of @code{operating-system}:
7426 (use-package-modules base)
7430 (locale-libcs (list glibc-2.21 (canonical-package glibc))))
7433 This example would lead to a system containing locale definitions for
7434 both libc 2.21 and the current version of libc in
7435 @file{/run/current-system/locale}.
7439 @subsection Services
7441 @cindex system services
7442 An important part of preparing an @code{operating-system} declaration is
7443 listing @dfn{system services} and their configuration (@pxref{Using the
7444 Configuration System}). System services are typically daemons launched
7445 when the system boots, or other actions needed at that time---e.g.,
7446 configuring network access.
7448 GuixSD has a broad definition of ``service'' (@pxref{Service
7449 Composition}), but many services are managed by the GNU@tie{}Shepherd
7450 (@pxref{Shepherd Services}). On a running system, the @command{herd}
7451 command allows you to list the available services, show their status,
7452 start and stop them, or do other specific operations (@pxref{Jump
7453 Start,,, shepherd, The GNU Shepherd Manual}). For example:
7459 The above command, run as @code{root}, lists the currently defined
7460 services. The @command{herd doc} command shows a synopsis of the given
7465 Run libc's name service cache daemon (nscd).
7468 The @command{start}, @command{stop}, and @command{restart} sub-commands
7469 have the effect you would expect. For instance, the commands below stop
7470 the nscd service and restart the Xorg display server:
7474 Service nscd has been stopped.
7475 # herd restart xorg-server
7476 Service xorg-server has been stopped.
7477 Service xorg-server has been started.
7480 The following sections document the available services, starting with
7481 the core services, that may be used in an @code{operating-system}
7485 * Base Services:: Essential system services.
7486 * Scheduled Job Execution:: The mcron service.
7487 * Networking Services:: Network setup, SSH daemon, etc.
7488 * X Window:: Graphical display.
7489 * Desktop Services:: D-Bus and desktop services.
7490 * Database Services:: SQL databases.
7491 * Mail Services:: IMAP, POP3, SMTP, and all that.
7492 * Web Services:: Web servers.
7493 * Various Services:: Other services.
7497 @subsubsection Base Services
7499 The @code{(gnu services base)} module provides definitions for the basic
7500 services that one expects from the system. The services exported by
7501 this module are listed below.
7503 @defvr {Scheme Variable} %base-services
7504 This variable contains a list of basic services (@pxref{Service Types
7505 and Services}, for more information on service objects) one would
7506 expect from the system: a login service (mingetty) on each tty, syslogd,
7507 the libc name service cache daemon (nscd), the udev device manager, and
7510 This is the default value of the @code{services} field of
7511 @code{operating-system} declarations. Usually, when customizing a
7512 system, you will want to append services to @var{%base-services}, like
7516 (cons* (avahi-service) (lsh-service) %base-services)
7520 @deffn {Scheme Procedure} host-name-service @var{name}
7521 Return a service that sets the host name to @var{name}.
7524 @deffn {Scheme Procedure} mingetty-service @var{config}
7525 Return a service to run mingetty according to @var{config}, a
7526 @code{<mingetty-configuration>} object, which specifies the tty to run, among
7530 @deftp {Data Type} mingetty-configuration
7531 This is the data type representing the configuration of Mingetty, which
7532 implements console log-in.
7537 The name of the console this Mingetty runs on---e.g., @code{"tty1"}.
7540 A file-like object containing the ``message of the day''.
7542 @item @code{auto-login} (default: @code{#f})
7543 When true, this field must be a string denoting the user name under
7544 which the system automatically logs in. When it is @code{#f}, a
7545 user name and password must be entered to log in.
7547 @item @code{login-program} (default: @code{#f})
7548 This must be either @code{#f}, in which case the default log-in program
7549 is used (@command{login} from the Shadow tool suite), or a gexp denoting
7550 the name of the log-in program.
7552 @item @code{login-pause?} (default: @code{#f})
7553 When set to @code{#t} in conjunction with @var{auto-login}, the user
7554 will have to press a key before the log-in shell is launched.
7556 @item @code{mingetty} (default: @var{mingetty})
7557 The Mingetty package to use.
7562 @cindex name service cache daemon
7564 @deffn {Scheme Procedure} nscd-service [@var{config}] [#:glibc glibc] @
7565 [#:name-services '()]
7566 Return a service that runs the libc name service cache daemon (nscd) with the
7567 given @var{config}---an @code{<nscd-configuration>} object. @xref{Name
7568 Service Switch}, for an example.
7571 @defvr {Scheme Variable} %nscd-default-configuration
7572 This is the default @code{<nscd-configuration>} value (see below) used
7573 by @code{nscd-service}. It uses the caches defined by
7574 @var{%nscd-default-caches}; see below.
7577 @deftp {Data Type} nscd-configuration
7578 This is the data type representing the name service cache daemon (nscd)
7583 @item @code{name-services} (default: @code{'()})
7584 List of packages denoting @dfn{name services} that must be visible to
7585 the nscd---e.g., @code{(list @var{nss-mdns})}.
7587 @item @code{glibc} (default: @var{glibc})
7588 Package object denoting the GNU C Library providing the @command{nscd}
7591 @item @code{log-file} (default: @code{"/var/log/nscd.log"})
7592 Name of the nscd log file. This is where debugging output goes when
7593 @code{debug-level} is strictly positive.
7595 @item @code{debug-level} (default: @code{0})
7596 Integer denoting the debugging levels. Higher numbers mean that more
7597 debugging output is logged.
7599 @item @code{caches} (default: @var{%nscd-default-caches})
7600 List of @code{<nscd-cache>} objects denoting things to be cached; see
7606 @deftp {Data Type} nscd-cache
7607 Data type representing a cache database of nscd and its parameters.
7611 @item @code{database}
7612 This is a symbol representing the name of the database to be cached.
7613 Valid values are @code{passwd}, @code{group}, @code{hosts}, and
7614 @code{services}, which designate the corresponding NSS database
7615 (@pxref{NSS Basics,,, libc, The GNU C Library Reference Manual}).
7617 @item @code{positive-time-to-live}
7618 @itemx @code{negative-time-to-live} (default: @code{20})
7619 A number representing the number of seconds during which a positive or
7620 negative lookup result remains in cache.
7622 @item @code{check-files?} (default: @code{#t})
7623 Whether to check for updates of the files corresponding to
7626 For instance, when @var{database} is @code{hosts}, setting this flag
7627 instructs nscd to check for updates in @file{/etc/hosts} and to take
7630 @item @code{persistent?} (default: @code{#t})
7631 Whether the cache should be stored persistently on disk.
7633 @item @code{shared?} (default: @code{#t})
7634 Whether the cache should be shared among users.
7636 @item @code{max-database-size} (default: 32@tie{}MiB)
7637 Maximum size in bytes of the database cache.
7639 @c XXX: 'suggested-size' and 'auto-propagate?' seem to be expert
7640 @c settings, so leave them out.
7645 @defvr {Scheme Variable} %nscd-default-caches
7646 List of @code{<nscd-cache>} objects used by default by
7647 @code{nscd-configuration} (see above).
7649 It enables persistent and aggressive caching of service and host name
7650 lookups. The latter provides better host name lookup performance,
7651 resilience in the face of unreliable name servers, and also better
7652 privacy---often the result of host name lookups is in local cache, so
7653 external name servers do not even need to be queried.
7657 @deffn {Scheme Procedure} syslog-service @
7658 [#:config-file @var{%default-syslog.conf}]
7659 Return a service that runs @command{syslogd}. If the configuration file
7660 name @var{config-file} is not specified, use some reasonable default
7663 @xref{syslogd invocation,,, inetutils, GNU Inetutils}, for more
7664 information on the configuration file syntax.
7667 @anchor{guix-configuration-type}
7668 @deftp {Data Type} guix-configuration
7669 This data type represents the configuration of the Guix build daemon.
7670 @xref{Invoking guix-daemon}, for more information.
7673 @item @code{guix} (default: @var{guix})
7674 The Guix package to use.
7676 @item @code{build-group} (default: @code{"guixbuild"})
7677 Name of the group for build user accounts.
7679 @item @code{build-accounts} (default: @code{10})
7680 Number of build user accounts to create.
7682 @item @code{authorize-key?} (default: @code{#t})
7683 Whether to authorize the substitute key for @code{hydra.gnu.org}
7684 (@pxref{Substitutes}).
7686 @item @code{use-substitutes?} (default: @code{#t})
7687 Whether to use substitutes.
7689 @item @code{substitute-urls} (default: @var{%default-substitute-urls})
7690 The list of URLs where to look for substitutes by default.
7692 @item @code{extra-options} (default: @code{'()})
7693 List of extra command-line options for @command{guix-daemon}.
7695 @item @code{lsof} (default: @var{lsof})
7696 @itemx @code{lsh} (default: @var{lsh})
7697 The lsof and lsh packages to use.
7702 @deffn {Scheme Procedure} guix-service @var{config}
7703 Return a service that runs the Guix build daemon according to
7707 @deffn {Scheme Procedure} udev-service [#:udev udev]
7708 Run @var{udev}, which populates the @file{/dev} directory dynamically.
7711 @deffn {Scheme Procedure} urandom-seed-service @var{#f}
7712 Save some entropy in @var{%random-seed-file} to seed @file{/dev/urandom}
7716 @defvr {Scheme Variable} %random-seed-file
7717 This is the name of the file where some random bytes are saved by
7718 @var{urandom-seed-service} to seed @file{/dev/urandom} when rebooting.
7719 It defaults to @file{/var/lib/random-seed}.
7722 @deffn {Scheme Procedure} console-keymap-service @var{files} ...
7723 @cindex keyboard layout
7724 Return a service to load console keymaps from @var{files} using
7725 @command{loadkeys} command. Most likely, you want to load some default
7726 keymap, which can be done like this:
7729 (console-keymap-service "dvorak")
7732 Or, for example, for a Swedish keyboard, you may need to combine
7733 the following keymaps:
7735 (console-keymap-service "se-lat6" "se-fi-lat6")
7738 Also you can specify a full file name (or file names) of your keymap(s).
7739 See @code{man loadkeys} for details.
7743 @deffn {Scheme Procedure} gpm-service [#:gpm @var{gpm}] @
7745 Run @var{gpm}, the general-purpose mouse daemon, with the given
7746 command-line @var{options}. GPM allows users to use the mouse in the console,
7747 notably to select, copy, and paste text. The default value of @var{options}
7748 uses the @code{ps2} protocol, which works for both USB and PS/2 mice.
7750 This service is not part of @var{%base-services}.
7753 @anchor{guix-publish-service}
7754 @deffn {Scheme Procedure} guix-publish-service [#:guix @var{guix}] @
7755 [#:port 80] [#:host "localhost"]
7756 Return a service that runs @command{guix publish} listening on @var{host}
7757 and @var{port} (@pxref{Invoking guix publish}).
7759 This assumes that @file{/etc/guix} already contains a signing key pair as
7760 created by @command{guix archive --generate-key} (@pxref{Invoking guix
7761 archive}). If that is not the case, the service will fail to start.
7764 @anchor{rngd-service}
7765 @deffn {Scheme Procedure} rngd-service [#:rng-tools @var{rng-tools}] @
7766 [#:device "/dev/hwrng"]
7767 Return a service that runs the @command{rngd} program from @var{rng-tools}
7768 to add @var{device} to the kernel's entropy pool. The service will fail if
7769 @var{device} does not exist.
7772 @anchor{pam-limits-service}
7773 @cindex session limits
7776 @deffn {Scheme Procedure} pam-limits-service [#:limits @var{limits}]
7778 Return a service that installs a configuration file for the
7779 @uref{http://linux-pam.org/Linux-PAM-html/sag-pam_limits.html,
7780 @code{pam_limits} module}. The procedure optionally takes a list of
7781 @code{pam-limits-entry} values, which can be used to specify
7782 @code{ulimit} limits and nice priority limits to user sessions.
7784 The following limits definition sets two hard and soft limits for all
7785 login sessions of users in the @code{realtime} group:
7790 (pam-limits-entry "@@realtime" 'both 'rtprio 99)
7791 (pam-limits-entry "@@realtime" 'both 'memlock 'unlimited)))
7794 The first entry increases the maximum realtime priority for
7795 non-privileged processes; the second entry lifts any restriction of the
7796 maximum address space that can be locked in memory. These settings are
7797 commonly used for real-time audio systems.
7800 @node Scheduled Job Execution
7801 @subsubsection Scheduled Job Execution
7804 @cindex scheduling jobs
7805 The @code{(gnu services mcron)} module provides an interface to
7806 GNU@tie{}mcron, a daemon to run jobs at scheduled times (@pxref{Top,,,
7807 mcron, GNU@tie{}mcron}). GNU@tie{}mcron is similar to the traditional
7808 Unix @command{cron} daemon; the main difference is that it is
7809 implemented in Guile Scheme, which provides a lot of flexibility when
7810 specifying the scheduling of jobs and their actions.
7812 The example below defines an operating system that runs the
7813 @command{updatedb} (@pxref{Invoking updatedb,,, find, Finding Files})
7814 and the @command{guix gc} commands (@pxref{Invoking guix gc}) daily, as
7815 well as the @command{mkid} command on behalf of an unprivileged user
7816 (@pxref{mkid invocation,,, idutils, ID Database Utilities}). It uses
7817 gexps to introduce job definitions that are passed to mcron
7818 (@pxref{G-Expressions}).
7821 (use-modules (guix) (gnu) (gnu services mcron))
7822 (use-package-modules base idutils)
7824 (define updatedb-job
7825 ;; Run 'updatedb' at 3AM every day. Here we write the
7826 ;; job's action as a Scheme procedure.
7827 #~(job '(next-hour '(3))
7829 (execl (string-append #$findutils "/bin/updatedb")
7831 "--prunepaths=/tmp /var/tmp /gnu/store"))))
7833 (define garbage-collector-job
7834 ;; Collect garbage 5 minutes after midnight every day.
7835 ;; The job's action is a shell command.
7836 #~(job "5 0 * * *" ;Vixie cron syntax
7840 ;; Update the index database as user "charlie" at 12:15PM
7841 ;; and 19:15PM. This runs from the user's home directory.
7842 #~(job '(next-minute-from (next-hour '(12 19)) '(15))
7843 (string-append #$idutils "/bin/mkid src")
7848 (services (cons (mcron-service (list garbage-collector-job
7854 @xref{Guile Syntax, mcron job specifications,, mcron, GNU@tie{}mcron},
7855 for more information on mcron job specifications. Below is the
7856 reference of the mcron service.
7858 @deffn {Scheme Procedure} mcron-service @var{jobs} [#:mcron @var{mcron2}]
7859 Return an mcron service running @var{mcron} that schedules @var{jobs}, a
7860 list of gexps denoting mcron job specifications.
7862 This is a shorthand for:
7864 (service mcron-service-type
7865 (mcron-configuration (mcron mcron) (jobs jobs)))
7869 @defvr {Scheme Variable} mcron-service-type
7870 This is the type of the @code{mcron} service, whose value is an
7871 @code{mcron-configuration} object.
7873 This service type can be the target of a service extension that provides
7874 it additional job specifications (@pxref{Service Composition}). In
7875 other words, it is possible to define services that provide additional
7879 @deftp {Data Type} mcron-configuration
7880 Data type representing the configuration of mcron.
7883 @item @code{mcron} (default: @var{mcron2})
7884 The mcron package to use.
7887 This is a list of gexps (@pxref{G-Expressions}), where each gexp
7888 corresponds to an mcron job specification (@pxref{Syntax, mcron job
7889 specifications,, mcron, GNU@tie{}mcron}).
7894 @node Networking Services
7895 @subsubsection Networking Services
7897 The @code{(gnu services networking)} module provides services to configure
7898 the network interface.
7900 @cindex DHCP, networking service
7901 @deffn {Scheme Procedure} dhcp-client-service [#:dhcp @var{isc-dhcp}]
7902 Return a service that runs @var{dhcp}, a Dynamic Host Configuration
7903 Protocol (DHCP) client, on all the non-loopback network interfaces.
7906 @deffn {Scheme Procedure} static-networking-service @var{interface} @var{ip} @
7907 [#:gateway #f] [#:name-servers @code{'()}]
7908 Return a service that starts @var{interface} with address @var{ip}. If
7909 @var{gateway} is true, it must be a string specifying the default network
7914 @cindex network management
7915 @deffn {Scheme Procedure} wicd-service [#:wicd @var{wicd}]
7916 Return a service that runs @url{https://launchpad.net/wicd,Wicd}, a network
7917 management daemon that aims to simplify wired and wireless networking.
7919 This service adds the @var{wicd} package to the global profile, providing
7920 several commands to interact with the daemon and configure networking:
7921 @command{wicd-client}, a graphical user interface, and the @command{wicd-cli}
7922 and @command{wicd-curses} user interfaces.
7925 @cindex NetworkManager
7926 @deffn {Scheme Procedure} network-manager-service @
7927 [#:network-manager @var{network-manager}]
7928 Return a service that runs NetworkManager, a network connection manager
7929 attempting to keep network connectivity active when available.
7933 @deffn {Scheme Procedure} connman-service @
7934 [#:connman @var{connman}]
7935 Return a service that runs @url{https://01.org/connman,Connman}, a network
7938 This service adds the @var{connman} package to the global profile, providing
7939 several the @command{connmanctl} command to interact with the daemon and
7940 configure networking."
7943 @deffn {Scheme Procedure} ntp-service [#:ntp @var{ntp}] @
7944 [#:name-service @var{%ntp-servers}]
7945 Return a service that runs the daemon from @var{ntp}, the
7946 @uref{http://www.ntp.org, Network Time Protocol package}. The daemon will
7947 keep the system clock synchronized with that of @var{servers}.
7950 @defvr {Scheme Variable} %ntp-servers
7951 List of host names used as the default NTP servers.
7954 @deffn {Scheme Procedure} tor-service [@var{config-file}] [#:tor @var{tor}]
7955 Return a service to run the @uref{https://torproject.org, Tor} anonymous
7958 The daemon runs as the @code{tor} unprivileged user. It is passed
7959 @var{config-file}, a file-like object, with an additional @code{User tor} line
7960 and lines for hidden services added via @code{tor-hidden-service}. Run
7961 @command{man tor} for information about the configuration file.
7964 @cindex hidden service
7965 @deffn {Scheme Procedure} tor-hidden-service @var{name} @var{mapping}
7966 Define a new Tor @dfn{hidden service} called @var{name} and implementing
7967 @var{mapping}. @var{mapping} is a list of port/host tuples, such as:
7970 '((22 "127.0.0.1:22")
7971 (80 "127.0.0.1:8080"))
7974 In this example, port 22 of the hidden service is mapped to local port 22, and
7975 port 80 is mapped to local port 8080.
7977 This creates a @file{/var/lib/tor/hidden-services/@var{name}} directory, where
7978 the @file{hostname} file contains the @code{.onion} host name for the hidden
7981 See @uref{https://www.torproject.org/docs/tor-hidden-service.html.en, the Tor
7982 project's documentation} for more information.
7985 @deffn {Scheme Procedure} bitlbee-service [#:bitlbee bitlbee] @
7986 [#:interface "127.0.0.1"] [#:port 6667] @
7987 [#:extra-settings ""]
7988 Return a service that runs @url{http://bitlbee.org,BitlBee}, a daemon that
7989 acts as a gateway between IRC and chat networks.
7991 The daemon will listen to the interface corresponding to the IP address
7992 specified in @var{interface}, on @var{port}. @code{127.0.0.1} means that only
7993 local clients can connect, whereas @code{0.0.0.0} means that connections can
7994 come from any networking interface.
7996 In addition, @var{extra-settings} specifies a string to append to the
8000 Furthermore, @code{(gnu services ssh)} provides the following services.
8002 @deffn {Scheme Procedure} lsh-service [#:host-key "/etc/lsh/host-key"] @
8003 [#:daemonic? #t] [#:interfaces '()] [#:port-number 22] @
8004 [#:allow-empty-passwords? #f] [#:root-login? #f] @
8005 [#:syslog-output? #t] [#:x11-forwarding? #t] @
8006 [#:tcp/ip-forwarding? #t] [#:password-authentication? #t] @
8007 [#:public-key-authentication? #t] [#:initialize? #t]
8008 Run the @command{lshd} program from @var{lsh} to listen on port @var{port-number}.
8009 @var{host-key} must designate a file containing the host key, and readable
8012 When @var{daemonic?} is true, @command{lshd} will detach from the
8013 controlling terminal and log its output to syslogd, unless one sets
8014 @var{syslog-output?} to false. Obviously, it also makes lsh-service
8015 depend on existence of syslogd service. When @var{pid-file?} is true,
8016 @command{lshd} writes its PID to the file called @var{pid-file}.
8018 When @var{initialize?} is true, automatically create the seed and host key
8019 upon service activation if they do not exist yet. This may take long and
8020 require interaction.
8022 When @var{initialize?} is false, it is up to the user to initialize the
8023 randomness generator (@pxref{lsh-make-seed,,, lsh, LSH Manual}), and to create
8024 a key pair with the private key stored in file @var{host-key} (@pxref{lshd
8025 basics,,, lsh, LSH Manual}).
8027 When @var{interfaces} is empty, lshd listens for connections on all the
8028 network interfaces; otherwise, @var{interfaces} must be a list of host names
8031 @var{allow-empty-passwords?} specifies whether to accept log-ins with empty
8032 passwords, and @var{root-login?} specifies whether to accept log-ins as
8035 The other options should be self-descriptive.
8038 @deffn {Scheme Procedure} dropbear-service [@var{config}]
8039 Run the @uref{https://matt.ucc.asn.au/dropbear/dropbear.html,Dropbear SSH
8040 daemon} with the given @var{config}, a @code{<dropbear-configuration>}
8043 For example, to specify a Dropbear service listening on port 1234, add
8044 this call to the operating system's @code{services} field:
8047 (dropbear-service (dropbear-configuration
8048 (port-number 1234)))
8052 @deftp {Data Type} dropbear-configuration
8053 This data type represents the configuration of a Dropbear SSH daemon.
8056 @item @code{dropbear} (default: @var{dropbear})
8057 The Dropbear package to use.
8059 @item @code{port-number} (default: 22)
8060 The TCP port where the daemon waits for incoming connections.
8062 @item @code{syslog-output?} (default: @code{#t})
8063 Whether to enable syslog output.
8065 @item @code{pid-file} (default: @code{"/var/run/dropbear.pid"})
8066 File name of the daemon's PID file.
8068 @item @code{root-login?} (default: @code{#f})
8069 Whether to allow @code{root} logins.
8071 @item @code{allow-empty-passwords?} (default: @code{#f})
8072 Whether to allow empty passwords.
8074 @item @code{password-authentication?} (default: @code{#t})
8075 Whether to enable password-based authentication.
8079 @defvr {Scheme Variable} %facebook-host-aliases
8080 This variable contains a string for use in @file{/etc/hosts}
8081 (@pxref{Host Names,,, libc, The GNU C Library Reference Manual}). Each
8082 line contains a entry that maps a known server name of the Facebook
8083 on-line service---e.g., @code{www.facebook.com}---to the local
8084 host---@code{127.0.0.1} or its IPv6 equivalent, @code{::1}.
8086 This variable is typically used in the @code{hosts-file} field of an
8087 @code{operating-system} declaration (@pxref{operating-system Reference,
8088 @file{/etc/hosts}}):
8091 (use-modules (gnu) (guix))
8094 (host-name "mymachine")
8097 ;; Create a /etc/hosts file with aliases for "localhost"
8098 ;; and "mymachine", as well as for Facebook servers.
8100 (string-append (local-host-aliases host-name)
8101 %facebook-host-aliases))))
8104 This mechanism can prevent programs running locally, such as Web
8105 browsers, from accessing Facebook.
8108 The @code{(gnu services avahi)} provides the following definition.
8110 @deffn {Scheme Procedure} avahi-service [#:avahi @var{avahi}] @
8111 [#:host-name #f] [#:publish? #t] [#:ipv4? #t] @
8112 [#:ipv6? #t] [#:wide-area? #f] @
8113 [#:domains-to-browse '()] [#:debug? #f]
8114 Return a service that runs @command{avahi-daemon}, a system-wide
8115 mDNS/DNS-SD responder that allows for service discovery and
8116 "zero-configuration" host name lookups (see @uref{http://avahi.org/}), and
8117 extends the name service cache daemon (nscd) so that it can resolve
8118 @code{.local} host names using
8119 @uref{http://0pointer.de/lennart/projects/nss-mdns/, nss-mdns}. Additionally,
8120 add the @var{avahi} package to the system profile so that commands such as
8121 @command{avahi-browse} are directly usable.
8123 If @var{host-name} is different from @code{#f}, use that as the host name to
8124 publish for this machine; otherwise, use the machine's actual host name.
8126 When @var{publish?} is true, publishing of host names and services is allowed;
8127 in particular, avahi-daemon will publish the machine's host name and IP
8128 address via mDNS on the local network.
8130 When @var{wide-area?} is true, DNS-SD over unicast DNS is enabled.
8132 Boolean values @var{ipv4?} and @var{ipv6?} determine whether to use IPv4/IPv6
8138 @subsubsection X Window
8140 Support for the X Window graphical display system---specifically
8141 Xorg---is provided by the @code{(gnu services xorg)} module. Note that
8142 there is no @code{xorg-service} procedure. Instead, the X server is
8143 started by the @dfn{login manager}, currently SLiM.
8145 @deffn {Scheme Procedure} slim-service [#:allow-empty-passwords? #f] @
8146 [#:auto-login? #f] [#:default-user ""] [#:startx] @
8147 [#:theme @var{%default-slim-theme}] @
8148 [#:theme-name @var{%default-slim-theme-name}]
8149 Return a service that spawns the SLiM graphical login manager, which in
8150 turn starts the X display server with @var{startx}, a command as returned by
8151 @code{xorg-start-command}.
8155 SLiM automatically looks for session types described by the @file{.desktop}
8156 files in @file{/run/current-system/profile/share/xsessions} and allows users
8157 to choose a session from the log-in screen using @kbd{F1}. Packages such as
8158 @var{xfce}, @var{sawfish}, and @var{ratpoison} provide @file{.desktop} files;
8159 adding them to the system-wide set of packages automatically makes them
8160 available at the log-in screen.
8162 In addition, @file{~/.xsession} files are honored. When available,
8163 @file{~/.xsession} must be an executable that starts a window manager
8164 and/or other X clients.
8166 When @var{allow-empty-passwords?} is true, allow logins with an empty
8167 password. When @var{auto-login?} is true, log in automatically as
8170 If @var{theme} is @code{#f}, use the default log-in theme; otherwise
8171 @var{theme} must be a gexp denoting the name of a directory containing the
8172 theme to use. In that case, @var{theme-name} specifies the name of the
8176 @defvr {Scheme Variable} %default-theme
8177 @defvrx {Scheme Variable} %default-theme-name
8178 The G-Expression denoting the default SLiM theme and its name.
8181 @deffn {Scheme Procedure} xorg-start-command [#:guile] @
8182 [#:configuration-file #f] [#:xorg-server @var{xorg-server}]
8183 Return a derivation that builds a @var{guile} script to start the X server
8184 from @var{xorg-server}. @var{configuration-file} is the server configuration
8185 file or a derivation that builds it; when omitted, the result of
8186 @code{xorg-configuration-file} is used.
8188 Usually the X server is started by a login manager.
8191 @deffn {Scheme Procedure} xorg-configuration-file @
8192 [#:drivers '()] [#:resolutions '()] [#:extra-config '()]
8193 Return a configuration file for the Xorg server containing search paths for
8194 all the common drivers.
8196 @var{drivers} must be either the empty list, in which case Xorg chooses a
8197 graphics driver automatically, or a list of driver names that will be tried in
8198 this order---e.g., @code{(\"modesetting\" \"vesa\")}.
8200 Likewise, when @var{resolutions} is the empty list, Xorg chooses an
8201 appropriate screen resolution; otherwise, it must be a list of
8202 resolutions---e.g., @code{((1024 768) (640 480))}.
8204 Last, @var{extra-config} is a list of strings or objects appended to the
8205 @code{text-file*} argument list. It is used to pass extra text to be added
8206 verbatim to the configuration file.
8209 @deffn {Scheme Procedure} screen-locker-service @var{package} [@var{name}]
8210 Add @var{package}, a package for a screen-locker or screen-saver whose
8211 command is @var{program}, to the set of setuid programs and add a PAM entry
8212 for it. For example:
8215 (screen-locker-service xlockmore "xlock")
8218 makes the good ol' XlockMore usable.
8222 @node Desktop Services
8223 @subsubsection Desktop Services
8225 The @code{(gnu services desktop)} module provides services that are
8226 usually useful in the context of a ``desktop'' setup---that is, on a
8227 machine running a graphical display server, possibly with graphical user
8228 interfaces, etc. It also defines services that provide specific desktop
8229 environments like GNOME and XFCE.
8231 To simplify things, the module defines a variable containing the set of
8232 services that users typically expect on a machine with a graphical
8233 environment and networking:
8235 @defvr {Scheme Variable} %desktop-services
8236 This is a list of services that builds upon @var{%base-services} and
8237 adds or adjusts services for a typical ``desktop'' setup.
8239 In particular, it adds a graphical login manager (@pxref{X Window,
8240 @code{slim-service}}), screen lockers,
8241 a network management tool (@pxref{Networking
8242 Services, @code{wicd-service}}), energy and color management services,
8243 the @code{elogind} login and seat manager, the Polkit privilege service,
8244 the GeoClue location service, an NTP client (@pxref{Networking
8245 Services}), the Avahi daemon, and has the name service switch service
8246 configured to be able to use @code{nss-mdns} (@pxref{Name Service
8250 The @var{%desktop-services} variable can be used as the @code{services}
8251 field of an @code{operating-system} declaration (@pxref{operating-system
8252 Reference, @code{services}}).
8254 Additionally, the @code{gnome-desktop-service} and
8255 @code{xfce-desktop-service} procedures can add GNOME and/or XFCE to a
8256 system. To ``add GNOME'' means that system-level services like the
8257 backlight adjustment helpers and the power management utilities are
8258 added to the system, extending @code{polkit} and @code{dbus}
8259 appropriately, allowing GNOME to operate with elevated privileges on a
8260 limited number of special-purpose system interfaces. Additionally,
8261 adding a service made by @code{gnome-desktop-service} adds the GNOME
8262 metapackage to the system profile. Likewise, adding the XFCE service
8263 not only adds the @code{xfce} metapackage to the system profile, but it
8264 also gives the Thunar file manager the ability to open a ``root-mode''
8265 file management window, if the user authenticates using the
8266 administrator's password via the standard polkit graphical interface.
8268 @deffn {Scheme Procedure} gnome-desktop-service
8269 Return a service that adds the @code{gnome} package to the system
8270 profile, and extends polkit with the actions from
8271 @code{gnome-settings-daemon}.
8274 @deffn {Scheme Procedure} xfce-desktop-service
8275 Return a service that adds the @code{xfce} package to the system profile,
8276 and extends polkit with the abilit for @code{thunar} to manipulate the
8277 file system as root from within a user session, after the user has
8278 authenticated with the administrator's password.
8281 Because the GNOME and XFCE desktop services pull in so many packages,
8282 the default @code{%desktop-services} variable doesn't include either of
8283 them by default. To add GNOME or XFCE, just @code{cons} them onto
8284 @code{%desktop-services} in the @code{services} field of your
8285 @code{operating-system}:
8289 (use-service-modules desktop)
8292 ;; cons* adds items to the list given as its last argument.
8293 (services (cons* (gnome-desktop-service)
8294 (xfce-desktop-service)
8299 These desktop environments will then be available as options in the
8300 graphical login window.
8302 The actual service definitions included in @code{%desktop-services} and
8303 provided by @code{(gnu services dbus)} and @code{(gnu services desktop)}
8304 are described below.
8306 @deffn {Scheme Procedure} dbus-service [#:dbus @var{dbus}] [#:services '()]
8307 Return a service that runs the ``system bus'', using @var{dbus}, with
8308 support for @var{services}.
8310 @uref{http://dbus.freedesktop.org/, D-Bus} is an inter-process communication
8311 facility. Its system bus is used to allow system services to communicate
8312 and to be notified of system-wide events.
8314 @var{services} must be a list of packages that provide an
8315 @file{etc/dbus-1/system.d} directory containing additional D-Bus configuration
8316 and policy files. For example, to allow avahi-daemon to use the system bus,
8317 @var{services} must be equal to @code{(list avahi)}.
8320 @deffn {Scheme Procedure} elogind-service [#:config @var{config}]
8321 Return a service that runs the @code{elogind} login and
8322 seat management daemon. @uref{https://github.com/andywingo/elogind,
8323 Elogind} exposes a D-Bus interface that can be used to know which users
8324 are logged in, know what kind of sessions they have open, suspend the
8325 system, inhibit system suspend, reboot the system, and other tasks.
8327 Elogind handles most system-level power events for a computer, for
8328 example suspending the system when a lid is closed, or shutting it down
8329 when the power button is pressed.
8331 The @var{config} keyword argument specifies the configuration for
8332 elogind, and should be the result of an @code{(elogind-configuration
8333 (@var{parameter} @var{value})...)} invocation. Available parameters and
8334 their default values are:
8337 @item kill-user-processes?
8339 @item kill-only-users
8341 @item kill-exclude-users
8343 @item inhibit-delay-max-seconds
8345 @item handle-power-key
8347 @item handle-suspend-key
8349 @item handle-hibernate-key
8351 @item handle-lid-switch
8353 @item handle-lid-switch-docked
8355 @item power-key-ignore-inhibited?
8357 @item suspend-key-ignore-inhibited?
8359 @item hibernate-key-ignore-inhibited?
8361 @item lid-switch-ignore-inhibited?
8363 @item holdoff-timeout-seconds
8367 @item idle-action-seconds
8369 @item runtime-directory-size-percent
8371 @item runtime-directory-size
8376 @code{("mem" "standby" "freeze")}
8379 @item hibernate-state
8381 @item hibernate-mode
8382 @code{("platform" "shutdown")}
8383 @item hybrid-sleep-state
8385 @item hybrid-sleep-mode
8386 @code{("suspend" "platform" "shutdown")}
8390 @deffn {Scheme Procedure} polkit-service @
8391 [#:polkit @var{polkit}]
8392 Return a service that runs the
8393 @uref{http://www.freedesktop.org/wiki/Software/polkit/, Polkit privilege
8394 management service}, which allows system administrators to grant access to
8395 privileged operations in a structured way. By querying the Polkit service, a
8396 privileged system component can know when it should grant additional
8397 capabilities to ordinary users. For example, an ordinary user can be granted
8398 the capability to suspend the system if the user is logged in locally.
8401 @deffn {Scheme Procedure} upower-service [#:upower @var{upower}] @
8402 [#:watts-up-pro? #f] @
8403 [#:poll-batteries? #t] @
8404 [#:ignore-lid? #f] @
8405 [#:use-percentage-for-policy? #f] @
8406 [#:percentage-low 10] @
8407 [#:percentage-critical 3] @
8408 [#:percentage-action 2] @
8410 [#:time-critical 300] @
8411 [#:time-action 120] @
8412 [#:critical-power-action 'hybrid-sleep]
8413 Return a service that runs @uref{http://upower.freedesktop.org/,
8414 @command{upowerd}}, a system-wide monitor for power consumption and battery
8415 levels, with the given configuration settings. It implements the
8416 @code{org.freedesktop.UPower} D-Bus interface, and is notably used by
8420 @deffn {Scheme Procedure} udisks-service [#:udisks @var{udisks}]
8421 Return a service for @uref{http://udisks.freedesktop.org/docs/latest/,
8422 UDisks}, a @dfn{disk management} daemon that provides user interfaces with
8423 notifications and ways to mount/unmount disks. Programs that talk to UDisks
8424 include the @command{udisksctl} command, part of UDisks, and GNOME Disks.
8427 @deffn {Scheme Procedure} colord-service [#:colord @var{colord}]
8428 Return a service that runs @command{colord}, a system service with a D-Bus
8429 interface to manage the color profiles of input and output devices such as
8430 screens and scanners. It is notably used by the GNOME Color Manager graphical
8431 tool. See @uref{http://www.freedesktop.org/software/colord/, the colord web
8432 site} for more information.
8435 @deffn {Scheme Procedure} geoclue-application name [#:allowed? #t] [#:system? #f] [#:users '()]
8436 Return a configuration allowing an application to access GeoClue
8437 location data. @var{name} is the Desktop ID of the application, without
8438 the @code{.desktop} part. If @var{allowed?} is true, the application
8439 will have access to location information by default. The boolean
8440 @var{system?} value indicates whether an application is a system component
8441 or not. Finally @var{users} is a list of UIDs of all users for which
8442 this application is allowed location info access. An empty users list
8443 means that all users are allowed.
8446 @defvr {Scheme Variable} %standard-geoclue-applications
8447 The standard list of well-known GeoClue application configurations,
8448 granting authority to the GNOME date-and-time utility to ask for the
8449 current location in order to set the time zone, and allowing the
8450 IceCat and Epiphany web browsers to request location information.
8451 IceCat and Epiphany both query the user before allowing a web page to
8452 know the user's location.
8455 @deffn {Scheme Procedure} geoclue-service [#:colord @var{colord}] @
8457 [#:wifi-geolocation-url "https://location.services.mozilla.com/v1/geolocate?key=geoclue"] @
8459 [#:wifi-submission-url "https://location.services.mozilla.com/v1/submit?key=geoclue"] @
8460 [#:submission-nick "geoclue"] @
8461 [#:applications %standard-geoclue-applications]
8462 Return a service that runs the GeoClue location service. This service
8463 provides a D-Bus interface to allow applications to request access to a
8464 user's physical location, and optionally to add information to online
8465 location databases. See
8466 @uref{https://wiki.freedesktop.org/www/Software/GeoClue/, the GeoClue
8467 web site} for more information.
8470 @deffn {Scheme Procedure} bluetooth-service [#:bluez @var{bluez}]
8471 Return a service that runs the @command{bluetoothd} daemon, which manages
8472 all the Bluetooth devices and provides a number of D-Bus interfaces.
8474 Users need to be in the @code{lp} group to access the D-Bus service.
8477 @node Database Services
8478 @subsubsection Database Services
8480 The @code{(gnu services databases)} module provides the following services.
8482 @deffn {Scheme Procedure} postgresql-service [#:postgresql postgresql] @
8483 [#:config-file] [#:data-directory ``/var/lib/postgresql/data'']
8484 Return a service that runs @var{postgresql}, the PostgreSQL database
8487 The PostgreSQL daemon loads its runtime configuration from
8488 @var{config-file} and stores the database cluster in
8489 @var{data-directory}.
8492 @deffn {Scheme Procedure} mysql-service [#:config (mysql-configuration)]
8493 Return a service that runs @command{mysqld}, the MySQL or MariaDB
8496 The optional @var{config} argument specifies the configuration for
8497 @command{mysqld}, which should be a @code{<mysql-configuraiton>} object.
8500 @deftp {Data Type} mysql-configuration
8501 Data type representing the configuration of @var{mysql-service}.
8504 @item @code{mysql} (default: @var{mariadb})
8505 Package object of the MySQL database server, can be either @var{mariadb}
8508 For MySQL, a temorary root password will be displayed at activation time.
8509 For MariaDB, the root password is empty.
8514 @subsubsection Mail Services
8516 The @code{(gnu services mail)} module provides Guix service definitions
8517 for mail services. Currently the only implemented service is Dovecot,
8518 an IMAP, POP3, and LMTP server.
8520 Guix does not yet have a mail transfer agent (MTA), although for some
8521 lightweight purposes the @code{esmtp} relay-only MTA may suffice. Help
8522 is needed to properly integrate a full MTA, such as Postfix. Patches
8525 To add an IMAP/POP3 server to a GuixSD system, add a
8526 @code{dovecot-service} to the operating system definition:
8528 @deffn {Scheme Procedure} dovecot-service [#:config (dovecot-configuration)]
8529 Return a service that runs the Dovecot IMAP/POP3/LMTP mail server.
8532 By default, Dovecot does not need much configuration; the default
8533 configuration object created by @code{(dovecot-configuration)} will
8534 suffice if your mail is delivered to @code{~/Maildir}. A self-signed
8535 certificate will be generated for TLS-protected connections, though
8536 Dovecot will also listen on cleartext ports by default. There are a
8537 number of options, though, which mail administrators might need to change,
8538 and as is the case with other services, Guix allows the system
8539 administrator to specify these parameters via a uniform Scheme interface.
8541 For example, to specify that mail is located at @code{maildir~/.mail},
8542 one would instantiate the Dovecot service like this:
8545 (dovecot-service #:config
8546 (dovecot-configuration
8547 (mail-location "maildir:~/.mail")))
8550 The available configuration parameters follow. Each parameter
8551 definition is preceded by its type; for example, @samp{string-list foo}
8552 indicates that the @code{foo} parameter should be specified as a list of
8553 strings. There is also a way to specify the configuration as a string,
8554 if you have an old @code{dovecot.conf} file that you want to port over
8555 from some other system; see the end for more details.
8557 @c The following documentation was initially generated by
8558 @c (generate-documentation) in (gnu services mail). Manually maintained
8559 @c documentation is better, so we shouldn't hesitate to edit below as
8560 @c needed. However if the change you want to make to this documentation
8561 @c can be done in an automated way, it's probably easier to change
8562 @c (generate-documentation) than to make it below and have to deal with
8563 @c the churn as dovecot updates.
8565 Available @code{dovecot-configuration} fields are:
8567 @deftypevr {@code{dovecot-configuration} parameter} package dovecot
8568 The dovecot package.
8571 @deftypevr {@code{dovecot-configuration} parameter} comma-separated-string-list listen
8572 A list of IPs or hosts where to listen for connections. @samp{*}
8573 listens on all IPv4 interfaces, @samp{::} listens on all IPv6
8574 interfaces. If you want to specify non-default ports or anything more
8575 complex, customize the address and port fields of the
8576 @samp{inet-listener} of the specific services you are interested in.
8579 @deftypevr {@code{dovecot-configuration} parameter} protocol-configuration-list protocols
8580 List of protocols we want to serve. Available protocols include
8581 @samp{imap}, @samp{pop3}, and @samp{lmtp}.
8583 Available @code{protocol-configuration} fields are:
8585 @deftypevr {@code{protocol-configuration} parameter} string name
8586 The name of the protocol.
8589 @deftypevr {@code{protocol-configuration} parameter} string auth-socket-path
8590 UNIX socket path to the master authentication server to find users.
8591 This is used by imap (for shared users) and lda.
8592 It defaults to @samp{"/var/run/dovecot/auth-userdb"}.
8595 @deftypevr {@code{protocol-configuration} parameter} space-separated-string-list mail-plugins
8596 Space separated list of plugins to load.
8599 @deftypevr {@code{protocol-configuration} parameter} non-negative-integer mail-max-userip-connections
8600 Maximum number of IMAP connections allowed for a user from each IP
8601 address. NOTE: The username is compared case-sensitively.
8602 Defaults to @samp{10}.
8607 @deftypevr {@code{dovecot-configuration} parameter} service-configuration-list services
8608 List of services to enable. Available services include @samp{imap},
8609 @samp{imap-login}, @samp{pop3}, @samp{pop3-login}, @samp{auth}, and
8612 Available @code{service-configuration} fields are:
8614 @deftypevr {@code{service-configuration} parameter} string kind
8615 The service kind. Valid values include @code{director},
8616 @code{imap-login}, @code{pop3-login}, @code{lmtp}, @code{imap},
8617 @code{pop3}, @code{auth}, @code{auth-worker}, @code{dict},
8618 @code{tcpwrap}, @code{quota-warning}, or anything else.
8621 @deftypevr {@code{service-configuration} parameter} listener-configuration-list listeners
8622 Listeners for the service. A listener is either a
8623 @code{unix-listener-configuration}, a @code{fifo-listener-configuration}, or
8624 an @code{inet-listener-configuration}.
8625 Defaults to @samp{()}.
8627 Available @code{unix-listener-configuration} fields are:
8629 @deftypevr {@code{unix-listener-configuration} parameter} file-name path
8630 The file name on which to listen.
8633 @deftypevr {@code{unix-listener-configuration} parameter} string mode
8634 The access mode for the socket.
8635 Defaults to @samp{"0600"}.
8638 @deftypevr {@code{unix-listener-configuration} parameter} string user
8639 The user to own the socket.
8640 Defaults to @samp{""}.
8643 @deftypevr {@code{unix-listener-configuration} parameter} string group
8644 The group to own the socket.
8645 Defaults to @samp{""}.
8649 Available @code{fifo-listener-configuration} fields are:
8651 @deftypevr {@code{fifo-listener-configuration} parameter} file-name path
8652 The file name on which to listen.
8655 @deftypevr {@code{fifo-listener-configuration} parameter} string mode
8656 The access mode for the socket.
8657 Defaults to @samp{"0600"}.
8660 @deftypevr {@code{fifo-listener-configuration} parameter} string user
8661 The user to own the socket.
8662 Defaults to @samp{""}.
8665 @deftypevr {@code{fifo-listener-configuration} parameter} string group
8666 The group to own the socket.
8667 Defaults to @samp{""}.
8671 Available @code{inet-listener-configuration} fields are:
8673 @deftypevr {@code{inet-listener-configuration} parameter} string protocol
8674 The protocol to listen for.
8677 @deftypevr {@code{inet-listener-configuration} parameter} string address
8678 The address on which to listen, or empty for all addresses.
8679 Defaults to @samp{""}.
8682 @deftypevr {@code{inet-listener-configuration} parameter} non-negative-integer port
8683 The port on which to listen.
8686 @deftypevr {@code{inet-listener-configuration} parameter} boolean ssl?
8687 Whether to use SSL for this service; @samp{yes}, @samp{no}, or
8689 Defaults to @samp{#t}.
8694 @deftypevr {@code{service-configuration} parameter} non-negative-integer service-count
8695 Number of connections to handle before starting a new process.
8696 Typically the only useful values are 0 (unlimited) or 1. 1 is more
8697 secure, but 0 is faster. <doc/wiki/LoginProcess.txt>.
8698 Defaults to @samp{1}.
8701 @deftypevr {@code{service-configuration} parameter} non-negative-integer process-min-avail
8702 Number of processes to always keep waiting for more connections.
8703 Defaults to @samp{0}.
8706 @deftypevr {@code{service-configuration} parameter} non-negative-integer vsz-limit
8707 If you set @samp{service-count 0}, you probably need to grow
8709 Defaults to @samp{256000000}.
8714 @deftypevr {@code{dovecot-configuration} parameter} dict-configuration dict
8715 Dict configuration, as created by the @code{dict-configuration}
8718 Available @code{dict-configuration} fields are:
8720 @deftypevr {@code{dict-configuration} parameter} free-form-fields entries
8721 A list of key-value pairs that this dict should hold.
8722 Defaults to @samp{()}.
8727 @deftypevr {@code{dovecot-configuration} parameter} passdb-configuration-list passdbs
8728 A list of passdb configurations, each one created by the
8729 @code{passdb-configuration} constructor.
8731 Available @code{passdb-configuration} fields are:
8733 @deftypevr {@code{passdb-configuration} parameter} string driver
8734 The driver that the passdb should use. Valid values include
8735 @samp{pam}, @samp{passwd}, @samp{shadow}, @samp{bsdauth}, and
8737 Defaults to @samp{"pam"}.
8740 @deftypevr {@code{passdb-configuration} parameter} free-form-args args
8741 A list of key-value args to the passdb driver.
8742 Defaults to @samp{()}.
8747 @deftypevr {@code{dovecot-configuration} parameter} userdb-configuration-list userdbs
8748 List of userdb configurations, each one created by the
8749 @code{userdb-configuration} constructor.
8751 Available @code{userdb-configuration} fields are:
8753 @deftypevr {@code{userdb-configuration} parameter} string driver
8754 The driver that the userdb should use. Valid values include
8755 @samp{passwd} and @samp{static}.
8756 Defaults to @samp{"passwd"}.
8759 @deftypevr {@code{userdb-configuration} parameter} free-form-args args
8760 A list of key-value args to the userdb driver.
8761 Defaults to @samp{()}.
8764 @deftypevr {@code{userdb-configuration} parameter} free-form-args override-fields
8765 Override fields from passwd.
8766 Defaults to @samp{()}.
8771 @deftypevr {@code{dovecot-configuration} parameter} plugin-configuration plugin-configuration
8772 Plug-in configuration, created by the @code{plugin-configuration}
8776 @deftypevr {@code{dovecot-configuration} parameter} list-of-namespace-configuration namespaces
8777 List of namespaces. Each item in the list is created by the
8778 @code{namespace-configuration} constructor.
8780 Available @code{namespace-configuration} fields are:
8782 @deftypevr {@code{namespace-configuration} parameter} string name
8783 Name for this namespace.
8786 @deftypevr {@code{namespace-configuration} parameter} string type
8787 Namespace type: @samp{private}, @samp{shared} or @samp{public}.
8788 Defaults to @samp{"private"}.
8791 @deftypevr {@code{namespace-configuration} parameter} string separator
8792 Hierarchy separator to use. You should use the same separator for
8793 all namespaces or some clients get confused. @samp{/} is usually a good
8794 one. The default however depends on the underlying mail storage
8796 Defaults to @samp{""}.
8799 @deftypevr {@code{namespace-configuration} parameter} string prefix
8800 Prefix required to access this namespace. This needs to be
8801 different for all namespaces. For example @samp{Public/}.
8802 Defaults to @samp{""}.
8805 @deftypevr {@code{namespace-configuration} parameter} string location
8806 Physical location of the mailbox. This is in the same format as
8807 mail_location, which is also the default for it.
8808 Defaults to @samp{""}.
8811 @deftypevr {@code{namespace-configuration} parameter} boolean inbox?
8812 There can be only one INBOX, and this setting defines which
8814 Defaults to @samp{#f}.
8817 @deftypevr {@code{namespace-configuration} parameter} boolean hidden?
8818 If namespace is hidden, it's not advertised to clients via NAMESPACE
8819 extension. You'll most likely also want to set @samp{list? #f}. This is mostly
8820 useful when converting from another server with different namespaces
8821 which you want to deprecate but still keep working. For example you can
8822 create hidden namespaces with prefixes @samp{~/mail/}, @samp{~%u/mail/}
8824 Defaults to @samp{#f}.
8827 @deftypevr {@code{namespace-configuration} parameter} boolean list?
8828 Show the mailboxes under this namespace with the LIST command. This
8829 makes the namespace visible for clients that do not support the NAMESPACE
8830 extension. The special @code{children} value lists child mailboxes, but
8831 hides the namespace prefix.
8832 Defaults to @samp{#t}.
8835 @deftypevr {@code{namespace-configuration} parameter} boolean subscriptions?
8836 Namespace handles its own subscriptions. If set to @code{#f}, the
8837 parent namespace handles them. The empty prefix should always have this
8839 Defaults to @samp{#t}.
8842 @deftypevr {@code{namespace-configuration} parameter} mailbox-configuration-list mailboxes
8843 List of predefined mailboxes in this namespace.
8844 Defaults to @samp{()}.
8846 Available @code{mailbox-configuration} fields are:
8848 @deftypevr {@code{mailbox-configuration} parameter} string name
8849 Name for this mailbox.
8852 @deftypevr {@code{mailbox-configuration} parameter} string auto
8853 @samp{create} will automatically create this mailbox.
8854 @samp{subscribe} will both create and subscribe to the mailbox.
8855 Defaults to @samp{"no"}.
8858 @deftypevr {@code{mailbox-configuration} parameter} space-separated-string-list special-use
8859 List of IMAP @code{SPECIAL-USE} attributes as specified by RFC 6154.
8860 Valid values are @code{\All}, @code{\Archive}, @code{\Drafts},
8861 @code{\Flagged}, @code{\Junk}, @code{\Sent}, and @code{\Trash}.
8862 Defaults to @samp{()}.
8869 @deftypevr {@code{dovecot-configuration} parameter} file-name base-dir
8870 Base directory where to store runtime data.
8871 Defaults to @samp{"/var/run/dovecot/"}.
8874 @deftypevr {@code{dovecot-configuration} parameter} string login-greeting
8875 Greeting message for clients.
8876 Defaults to @samp{"Dovecot ready."}.
8879 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-trusted-networks
8880 List of trusted network ranges. Connections from these IPs are
8881 allowed to override their IP addresses and ports (for logging and for
8882 authentication checks). @samp{disable-plaintext-auth} is also ignored
8883 for these networks. Typically you would specify your IMAP proxy servers
8885 Defaults to @samp{()}.
8888 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-access-sockets
8889 List of login access check sockets (e.g. tcpwrap).
8890 Defaults to @samp{()}.
8893 @deftypevr {@code{dovecot-configuration} parameter} boolean verbose-proctitle?
8894 Show more verbose process titles (in ps). Currently shows user name
8895 and IP address. Useful for seeing who is actually using the IMAP
8896 processes (e.g. shared mailboxes or if the same uid is used for multiple
8898 Defaults to @samp{#f}.
8901 @deftypevr {@code{dovecot-configuration} parameter} boolean shutdown-clients?
8902 Should all processes be killed when Dovecot master process shuts down.
8903 Setting this to @code{#f} means that Dovecot can be upgraded without
8904 forcing existing client connections to close (although that could also
8905 be a problem if the upgrade is e.g. due to a security fix).
8906 Defaults to @samp{#t}.
8909 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer doveadm-worker-count
8910 If non-zero, run mail commands via this many connections to doveadm
8911 server, instead of running them directly in the same process.
8912 Defaults to @samp{0}.
8915 @deftypevr {@code{dovecot-configuration} parameter} string doveadm-socket-path
8916 UNIX socket or host:port used for connecting to doveadm server.
8917 Defaults to @samp{"doveadm-server"}.
8920 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list import-environment
8921 List of environment variables that are preserved on Dovecot startup
8922 and passed down to all of its child processes. You can also give
8923 key=value pairs to always set specific settings.
8926 @deftypevr {@code{dovecot-configuration} parameter} boolean disable-plaintext-auth?
8927 Disable LOGIN command and all other plaintext authentications unless
8928 SSL/TLS is used (LOGINDISABLED capability). Note that if the remote IP
8929 matches the local IP (i.e. you're connecting from the same computer),
8930 the connection is considered secure and plaintext authentication is
8931 allowed. See also ssl=required setting.
8932 Defaults to @samp{#t}.
8935 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer auth-cache-size
8936 Authentication cache size (e.g. @samp{#e10e6}). 0 means it's disabled.
8937 Note that bsdauth, PAM and vpopmail require @samp{cache-key} to be set
8938 for caching to be used.
8939 Defaults to @samp{0}.
8942 @deftypevr {@code{dovecot-configuration} parameter} string auth-cache-ttl
8943 Time to live for cached data. After TTL expires the cached record
8944 is no longer used, *except* if the main database lookup returns internal
8945 failure. We also try to handle password changes automatically: If
8946 user's previous authentication was successful, but this one wasn't, the
8947 cache isn't used. For now this works only with plaintext
8949 Defaults to @samp{"1 hour"}.
8952 @deftypevr {@code{dovecot-configuration} parameter} string auth-cache-negative-ttl
8953 TTL for negative hits (user not found, password mismatch).
8954 0 disables caching them completely.
8955 Defaults to @samp{"1 hour"}.
8958 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list auth-realms
8959 List of realms for SASL authentication mechanisms that need them.
8960 You can leave it empty if you don't want to support multiple realms.
8961 Many clients simply use the first one listed here, so keep the default
8963 Defaults to @samp{()}.
8966 @deftypevr {@code{dovecot-configuration} parameter} string auth-default-realm
8967 Default realm/domain to use if none was specified. This is used for
8968 both SASL realms and appending @@domain to username in plaintext
8970 Defaults to @samp{""}.
8973 @deftypevr {@code{dovecot-configuration} parameter} string auth-username-chars
8974 List of allowed characters in username. If the user-given username
8975 contains a character not listed in here, the login automatically fails.
8976 This is just an extra check to make sure user can't exploit any
8977 potential quote escaping vulnerabilities with SQL/LDAP databases. If
8978 you want to allow all characters, set this value to empty.
8979 Defaults to @samp{"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890.-_@@"}.
8982 @deftypevr {@code{dovecot-configuration} parameter} string auth-username-translation
8983 Username character translations before it's looked up from
8984 databases. The value contains series of from -> to characters. For
8985 example @samp{#@@/@@} means that @samp{#} and @samp{/} characters are
8986 translated to @samp{@@}.
8987 Defaults to @samp{""}.
8990 @deftypevr {@code{dovecot-configuration} parameter} string auth-username-format
8991 Username formatting before it's looked up from databases. You can
8992 use the standard variables here, e.g. %Lu would lowercase the username,
8993 %n would drop away the domain if it was given, or @samp{%n-AT-%d} would
8994 change the @samp{@@} into @samp{-AT-}. This translation is done after
8995 @samp{auth-username-translation} changes.
8996 Defaults to @samp{"%Lu"}.
8999 @deftypevr {@code{dovecot-configuration} parameter} string auth-master-user-separator
9000 If you want to allow master users to log in by specifying the master
9001 username within the normal username string (i.e. not using SASL
9002 mechanism's support for it), you can specify the separator character
9003 here. The format is then <username><separator><master username>.
9004 UW-IMAP uses @samp{*} as the separator, so that could be a good
9006 Defaults to @samp{""}.
9009 @deftypevr {@code{dovecot-configuration} parameter} string auth-anonymous-username
9010 Username to use for users logging in with ANONYMOUS SASL
9012 Defaults to @samp{"anonymous"}.
9015 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer auth-worker-max-count
9016 Maximum number of dovecot-auth worker processes. They're used to
9017 execute blocking passdb and userdb queries (e.g. MySQL and PAM).
9018 They're automatically created and destroyed as needed.
9019 Defaults to @samp{30}.
9022 @deftypevr {@code{dovecot-configuration} parameter} string auth-gssapi-hostname
9023 Host name to use in GSSAPI principal names. The default is to use
9024 the name returned by gethostname(). Use @samp{$ALL} (with quotes) to
9025 allow all keytab entries.
9026 Defaults to @samp{""}.
9029 @deftypevr {@code{dovecot-configuration} parameter} string auth-krb5-keytab
9030 Kerberos keytab to use for the GSSAPI mechanism. Will use the
9031 system default (usually /etc/krb5.keytab) if not specified. You may
9032 need to change the auth service to run as root to be able to read this
9034 Defaults to @samp{""}.
9037 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-use-winbind?
9038 Do NTLM and GSS-SPNEGO authentication using Samba's winbind daemon
9039 and @samp{ntlm-auth} helper.
9040 <doc/wiki/Authentication/Mechanisms/Winbind.txt>.
9041 Defaults to @samp{#f}.
9044 @deftypevr {@code{dovecot-configuration} parameter} file-name auth-winbind-helper-path
9045 Path for Samba's @samp{ntlm-auth} helper binary.
9046 Defaults to @samp{"/usr/bin/ntlm_auth"}.
9049 @deftypevr {@code{dovecot-configuration} parameter} string auth-failure-delay
9050 Time to delay before replying to failed authentications.
9051 Defaults to @samp{"2 secs"}.
9054 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-ssl-require-client-cert?
9055 Require a valid SSL client certificate or the authentication
9057 Defaults to @samp{#f}.
9060 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-ssl-username-from-cert?
9061 Take the username from client's SSL certificate, using
9062 @code{X509_NAME_get_text_by_NID()} which returns the subject's DN's
9064 Defaults to @samp{#f}.
9067 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list auth-mechanisms
9068 List of wanted authentication mechanisms. Supported mechanisms are:
9069 @samp{plain}, @samp{login}, @samp{digest-md5}, @samp{cram-md5},
9070 @samp{ntlm}, @samp{rpa}, @samp{apop}, @samp{anonymous}, @samp{gssapi},
9071 @samp{otp}, @samp{skey}, and @samp{gss-spnego}. NOTE: See also
9072 @samp{disable-plaintext-auth} setting.
9075 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list director-servers
9076 List of IPs or hostnames to all director servers, including ourself.
9077 Ports can be specified as ip:port. The default port is the same as what
9078 director service's @samp{inet-listener} is using.
9079 Defaults to @samp{()}.
9082 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list director-mail-servers
9083 List of IPs or hostnames to all backend mail servers. Ranges are
9084 allowed too, like 10.0.0.10-10.0.0.30.
9085 Defaults to @samp{()}.
9088 @deftypevr {@code{dovecot-configuration} parameter} string director-user-expire
9089 How long to redirect users to a specific server after it no longer
9090 has any connections.
9091 Defaults to @samp{"15 min"}.
9094 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer director-doveadm-port
9095 TCP/IP port that accepts doveadm connections (instead of director
9096 connections) If you enable this, you'll also need to add
9097 @samp{inet-listener} for the port.
9098 Defaults to @samp{0}.
9101 @deftypevr {@code{dovecot-configuration} parameter} string director-username-hash
9102 How the username is translated before being hashed. Useful values
9103 include %Ln if user can log in with or without @@domain, %Ld if mailboxes
9104 are shared within domain.
9105 Defaults to @samp{"%Lu"}.
9108 @deftypevr {@code{dovecot-configuration} parameter} string log-path
9109 Log file to use for error messages. @samp{syslog} logs to syslog,
9110 @samp{/dev/stderr} logs to stderr.
9111 Defaults to @samp{"syslog"}.
9114 @deftypevr {@code{dovecot-configuration} parameter} string info-log-path
9115 Log file to use for informational messages. Defaults to
9117 Defaults to @samp{""}.
9120 @deftypevr {@code{dovecot-configuration} parameter} string debug-log-path
9121 Log file to use for debug messages. Defaults to
9122 @samp{info-log-path}.
9123 Defaults to @samp{""}.
9126 @deftypevr {@code{dovecot-configuration} parameter} string syslog-facility
9127 Syslog facility to use if you're logging to syslog. Usually if you
9128 don't want to use @samp{mail}, you'll use local0..local7. Also other
9129 standard facilities are supported.
9130 Defaults to @samp{"mail"}.
9133 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-verbose?
9134 Log unsuccessful authentication attempts and the reasons why they
9136 Defaults to @samp{#f}.
9139 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-verbose-passwords?
9140 In case of password mismatches, log the attempted password. Valid
9141 values are no, plain and sha1. sha1 can be useful for detecting brute
9142 force password attempts vs. user simply trying the same password over
9143 and over again. You can also truncate the value to n chars by appending
9145 Defaults to @samp{#f}.
9148 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-debug?
9149 Even more verbose logging for debugging purposes. Shows for example
9151 Defaults to @samp{#f}.
9154 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-debug-passwords?
9155 In case of password mismatches, log the passwords and used scheme so
9156 the problem can be debugged. Enabling this also enables
9158 Defaults to @samp{#f}.
9161 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-debug?
9162 Enable mail process debugging. This can help you figure out why
9163 Dovecot isn't finding your mails.
9164 Defaults to @samp{#f}.
9167 @deftypevr {@code{dovecot-configuration} parameter} boolean verbose-ssl?
9168 Show protocol level SSL errors.
9169 Defaults to @samp{#f}.
9172 @deftypevr {@code{dovecot-configuration} parameter} string log-timestamp
9173 Prefix for each line written to log file. % codes are in
9175 Defaults to @samp{"\"%b %d %H:%M:%S \""}.
9178 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-log-format-elements
9179 List of elements we want to log. The elements which have a
9180 non-empty variable value are joined together to form a comma-separated
9184 @deftypevr {@code{dovecot-configuration} parameter} string login-log-format
9185 Login log format. %s contains @samp{login-log-format-elements}
9186 string, %$ contains the data we want to log.
9187 Defaults to @samp{"%$: %s"}.
9190 @deftypevr {@code{dovecot-configuration} parameter} string mail-log-prefix
9191 Log prefix for mail processes. See doc/wiki/Variables.txt for list
9192 of possible variables you can use.
9193 Defaults to @samp{"\"%s(%u): \""}.
9196 @deftypevr {@code{dovecot-configuration} parameter} string deliver-log-format
9197 Format to use for logging mail deliveries. You can use variables:
9200 Delivery status message (e.g. @samp{saved to INBOX})
9212 Defaults to @samp{"msgid=%m: %$"}.
9215 @deftypevr {@code{dovecot-configuration} parameter} string mail-location
9216 Location for users' mailboxes. The default is empty, which means
9217 that Dovecot tries to find the mailboxes automatically. This won't work
9218 if the user doesn't yet have any mail, so you should explicitly tell
9219 Dovecot the full location.
9221 If you're using mbox, giving a path to the INBOX
9222 file (e.g. /var/mail/%u) isn't enough. You'll also need to tell Dovecot
9223 where the other mailboxes are kept. This is called the "root mail
9224 directory", and it must be the first path given in the
9225 @samp{mail-location} setting.
9227 There are a few special variables you can use, eg.:
9233 user part in user@@domain, same as %u if there's no domain
9235 domain part in user@@domain, empty if there's no domain
9240 See doc/wiki/Variables.txt for full list. Some examples:
9242 @item maildir:~/Maildir
9243 @item mbox:~/mail:INBOX=/var/mail/%u
9244 @item mbox:/var/mail/%d/%1n/%n:INDEX=/var/indexes/%d/%1n/%
9246 Defaults to @samp{""}.
9249 @deftypevr {@code{dovecot-configuration} parameter} string mail-uid
9250 System user and group used to access mails. If you use multiple,
9251 userdb can override these by returning uid or gid fields. You can use
9252 either numbers or names. <doc/wiki/UserIds.txt>.
9253 Defaults to @samp{""}.
9256 @deftypevr {@code{dovecot-configuration} parameter} string mail-gid
9258 Defaults to @samp{""}.
9261 @deftypevr {@code{dovecot-configuration} parameter} string mail-privileged-group
9262 Group to enable temporarily for privileged operations. Currently
9263 this is used only with INBOX when either its initial creation or
9264 dotlocking fails. Typically this is set to "mail" to give access to
9266 Defaults to @samp{""}.
9269 @deftypevr {@code{dovecot-configuration} parameter} string mail-access-groups
9270 Grant access to these supplementary groups for mail processes.
9271 Typically these are used to set up access to shared mailboxes. Note
9272 that it may be dangerous to set these if users can create
9273 symlinks (e.g. if "mail" group is set here, ln -s /var/mail ~/mail/var
9274 could allow a user to delete others' mailboxes, or ln -s
9275 /secret/shared/box ~/mail/mybox would allow reading it).
9276 Defaults to @samp{""}.
9279 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-full-filesystem-access?
9280 Allow full filesystem access to clients. There's no access checks
9281 other than what the operating system does for the active UID/GID. It
9282 works with both maildir and mboxes, allowing you to prefix mailboxes
9283 names with e.g. /path/ or ~user/.
9284 Defaults to @samp{#f}.
9287 @deftypevr {@code{dovecot-configuration} parameter} boolean mmap-disable?
9288 Don't use mmap() at all. This is required if you store indexes to
9289 shared filesystems (NFS or clustered filesystem).
9290 Defaults to @samp{#f}.
9293 @deftypevr {@code{dovecot-configuration} parameter} boolean dotlock-use-excl?
9294 Rely on @samp{O_EXCL} to work when creating dotlock files. NFS
9295 supports @samp{O_EXCL} since version 3, so this should be safe to use
9296 nowadays by default.
9297 Defaults to @samp{#t}.
9300 @deftypevr {@code{dovecot-configuration} parameter} string mail-fsync
9301 When to use fsync() or fdatasync() calls:
9304 Whenever necessary to avoid losing important data
9306 Useful with e.g. NFS when write()s are delayed
9308 Never use it (best performance, but crashes can lose data).
9310 Defaults to @samp{"optimized"}.
9313 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-nfs-storage?
9314 Mail storage exists in NFS. Set this to yes to make Dovecot flush
9315 NFS caches whenever needed. If you're using only a single mail server
9317 Defaults to @samp{#f}.
9320 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-nfs-index?
9321 Mail index files also exist in NFS. Setting this to yes requires
9322 @samp{mmap-disable? #t} and @samp{fsync-disable? #f}.
9323 Defaults to @samp{#f}.
9326 @deftypevr {@code{dovecot-configuration} parameter} string lock-method
9327 Locking method for index files. Alternatives are fcntl, flock and
9328 dotlock. Dotlocking uses some tricks which may create more disk I/O
9329 than other locking methods. NFS users: flock doesn't work, remember to
9330 change @samp{mmap-disable}.
9331 Defaults to @samp{"fcntl"}.
9334 @deftypevr {@code{dovecot-configuration} parameter} file-name mail-temp-dir
9335 Directory in which LDA/LMTP temporarily stores incoming mails >128
9337 Defaults to @samp{"/tmp"}.
9340 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer first-valid-uid
9341 Valid UID range for users. This is mostly to make sure that users can't
9342 log in as daemons or other system users. Note that denying root logins is
9343 hardcoded to dovecot binary and can't be done even if @samp{first-valid-uid}
9345 Defaults to @samp{500}.
9348 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer last-valid-uid
9350 Defaults to @samp{0}.
9353 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer first-valid-gid
9354 Valid GID range for users. Users having non-valid GID as primary group ID
9355 aren't allowed to log in. If user belongs to supplementary groups with
9356 non-valid GIDs, those groups are not set.
9357 Defaults to @samp{1}.
9360 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer last-valid-gid
9362 Defaults to @samp{0}.
9365 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-max-keyword-length
9366 Maximum allowed length for mail keyword name. It's only forced when
9367 trying to create new keywords.
9368 Defaults to @samp{50}.
9371 @deftypevr {@code{dovecot-configuration} parameter} colon-separated-file-name-list valid-chroot-dirs
9372 List of directories under which chrooting is allowed for mail
9373 processes (i.e. /var/mail will allow chrooting to /var/mail/foo/bar
9374 too). This setting doesn't affect @samp{login-chroot}
9375 @samp{mail-chroot} or auth chroot settings. If this setting is empty,
9376 "/./" in home dirs are ignored. WARNING: Never add directories here
9377 which local users can modify, that may lead to root exploit. Usually
9378 this should be done only if you don't allow shell access for users.
9379 <doc/wiki/Chrooting.txt>.
9380 Defaults to @samp{()}.
9383 @deftypevr {@code{dovecot-configuration} parameter} string mail-chroot
9384 Default chroot directory for mail processes. This can be overridden
9385 for specific users in user database by giving /./ in user's home
9386 directory (e.g. /home/./user chroots into /home). Note that usually
9387 there is no real need to do chrooting, Dovecot doesn't allow users to
9388 access files outside their mail directory anyway. If your home
9389 directories are prefixed with the chroot directory, append "/." to
9390 @samp{mail-chroot}. <doc/wiki/Chrooting.txt>.
9391 Defaults to @samp{""}.
9394 @deftypevr {@code{dovecot-configuration} parameter} file-name auth-socket-path
9395 UNIX socket path to master authentication server to find users.
9396 This is used by imap (for shared users) and lda.
9397 Defaults to @samp{"/var/run/dovecot/auth-userdb"}.
9400 @deftypevr {@code{dovecot-configuration} parameter} file-name mail-plugin-dir
9401 Directory where to look up mail plugins.
9402 Defaults to @samp{"/usr/lib/dovecot"}.
9405 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mail-plugins
9406 List of plugins to load for all services. Plugins specific to IMAP,
9407 LDA, etc. are added to this list in their own .conf files.
9408 Defaults to @samp{()}.
9411 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-cache-min-mail-count
9412 The minimum number of mails in a mailbox before updates are done to
9413 cache file. This allows optimizing Dovecot's behavior to do less disk
9414 writes at the cost of more disk reads.
9415 Defaults to @samp{0}.
9418 @deftypevr {@code{dovecot-configuration} parameter} string mailbox-idle-check-interval
9419 When IDLE command is running, mailbox is checked once in a while to
9420 see if there are any new mails or other changes. This setting defines
9421 the minimum time to wait between those checks. Dovecot can also use
9422 dnotify, inotify and kqueue to find out immediately when changes
9424 Defaults to @samp{"30 secs"}.
9427 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-save-crlf?
9428 Save mails with CR+LF instead of plain LF. This makes sending those
9429 mails take less CPU, especially with sendfile() syscall with Linux and
9430 FreeBSD. But it also creates a bit more disk I/O which may just make it
9431 slower. Also note that if other software reads the mboxes/maildirs,
9432 they may handle the extra CRs wrong and cause problems.
9433 Defaults to @samp{#f}.
9436 @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-stat-dirs?
9437 By default LIST command returns all entries in maildir beginning
9438 with a dot. Enabling this option makes Dovecot return only entries
9439 which are directories. This is done by stat()ing each entry, so it
9440 causes more disk I/O.
9441 (For systems setting struct @samp{dirent->d_type} this check is free
9442 and it's done always regardless of this setting).
9443 Defaults to @samp{#f}.
9446 @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-copy-with-hardlinks?
9447 When copying a message, do it with hard links whenever possible.
9448 This makes the performance much better, and it's unlikely to have any
9450 Defaults to @samp{#t}.
9453 @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-very-dirty-syncs?
9454 Assume Dovecot is the only MUA accessing Maildir: Scan cur/
9455 directory only when its mtime changes unexpectedly or when we can't find
9457 Defaults to @samp{#f}.
9460 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mbox-read-locks
9461 Which locking methods to use for locking mbox. There are four
9466 Create <mailbox>.lock file. This is the oldest and most NFS-safe
9467 solution. If you want to use /var/mail/ like directory, the users will
9468 need write access to that directory.
9470 Same as dotlock, but if it fails because of permissions or because there
9471 isn't enough disk space, just skip it.
9473 Use this if possible. Works with NFS too if lockd is used.
9475 May not exist in all systems. Doesn't work with NFS.
9477 May not exist in all systems. Doesn't work with NFS.
9480 You can use multiple locking methods; if you do the order they're declared
9481 in is important to avoid deadlocks if other MTAs/MUAs are using multiple
9482 locking methods as well. Some operating systems don't allow using some of
9483 them simultaneously.
9486 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mbox-write-locks
9490 @deftypevr {@code{dovecot-configuration} parameter} string mbox-lock-timeout
9491 Maximum time to wait for lock (all of them) before aborting.
9492 Defaults to @samp{"5 mins"}.
9495 @deftypevr {@code{dovecot-configuration} parameter} string mbox-dotlock-change-timeout
9496 If dotlock exists but the mailbox isn't modified in any way,
9497 override the lock file after this much time.
9498 Defaults to @samp{"2 mins"}.
9501 @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-dirty-syncs?
9502 When mbox changes unexpectedly we have to fully read it to find out
9503 what changed. If the mbox is large this can take a long time. Since
9504 the change is usually just a newly appended mail, it'd be faster to
9505 simply read the new mails. If this setting is enabled, Dovecot does
9506 this but still safely fallbacks to re-reading the whole mbox file
9507 whenever something in mbox isn't how it's expected to be. The only real
9508 downside to this setting is that if some other MUA changes message
9509 flags, Dovecot doesn't notice it immediately. Note that a full sync is
9510 done with SELECT, EXAMINE, EXPUNGE and CHECK commands.
9511 Defaults to @samp{#t}.
9514 @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-very-dirty-syncs?
9515 Like @samp{mbox-dirty-syncs}, but don't do full syncs even with SELECT,
9516 EXAMINE, EXPUNGE or CHECK commands. If this is set,
9517 @samp{mbox-dirty-syncs} is ignored.
9518 Defaults to @samp{#f}.
9521 @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-lazy-writes?
9522 Delay writing mbox headers until doing a full write sync (EXPUNGE
9523 and CHECK commands and when closing the mailbox). This is especially
9524 useful for POP3 where clients often delete all mails. The downside is
9525 that our changes aren't immediately visible to other MUAs.
9526 Defaults to @samp{#t}.
9529 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mbox-min-index-size
9530 If mbox size is smaller than this (e.g. 100k), don't write index
9531 files. If an index file already exists it's still read, just not
9533 Defaults to @samp{0}.
9536 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mdbox-rotate-size
9537 Maximum dbox file size until it's rotated.
9538 Defaults to @samp{2000000}.
9541 @deftypevr {@code{dovecot-configuration} parameter} string mdbox-rotate-interval
9542 Maximum dbox file age until it's rotated. Typically in days. Day
9543 begins from midnight, so 1d = today, 2d = yesterday, etc. 0 = check
9545 Defaults to @samp{"1d"}.
9548 @deftypevr {@code{dovecot-configuration} parameter} boolean mdbox-preallocate-space?
9549 When creating new mdbox files, immediately preallocate their size to
9550 @samp{mdbox-rotate-size}. This setting currently works only in Linux
9551 with some filesystems (ext4, xfs).
9552 Defaults to @samp{#f}.
9555 @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-dir
9556 sdbox and mdbox support saving mail attachments to external files,
9557 which also allows single instance storage for them. Other backends
9558 don't support this for now.
9560 WARNING: This feature hasn't been tested much yet. Use at your own risk.
9562 Directory root where to store mail attachments. Disabled, if empty.
9563 Defaults to @samp{""}.
9566 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-attachment-min-size
9567 Attachments smaller than this aren't saved externally. It's also
9568 possible to write a plugin to disable saving specific attachments
9570 Defaults to @samp{128000}.
9573 @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-fs
9574 Filesystem backend to use for saving attachments:
9577 No SiS done by Dovecot (but this might help FS's own deduplication)
9579 SiS with immediate byte-by-byte comparison during saving
9580 @item sis-queue posix
9581 SiS with delayed comparison and deduplication.
9583 Defaults to @samp{"sis posix"}.
9586 @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-hash
9587 Hash format to use in attachment filenames. You can add any text and
9588 variables: @code{%@{md4@}}, @code{%@{md5@}}, @code{%@{sha1@}},
9589 @code{%@{sha256@}}, @code{%@{sha512@}}, @code{%@{size@}}. Variables can be
9590 truncated, e.g. @code{%@{sha256:80@}} returns only first 80 bits.
9591 Defaults to @samp{"%@{sha1@}"}.
9594 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-process-limit
9596 Defaults to @samp{100}.
9599 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-client-limit
9601 Defaults to @samp{1000}.
9604 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-vsz-limit
9605 Default VSZ (virtual memory size) limit for service processes.
9606 This is mainly intended to catch and kill processes that leak memory
9607 before they eat up everything.
9608 Defaults to @samp{256000000}.
9611 @deftypevr {@code{dovecot-configuration} parameter} string default-login-user
9612 Login user is internally used by login processes. This is the most
9613 untrusted user in Dovecot system. It shouldn't have access to anything
9615 Defaults to @samp{"dovenull"}.
9618 @deftypevr {@code{dovecot-configuration} parameter} string default-internal-user
9619 Internal user is used by unprivileged processes. It should be
9620 separate from login user, so that login processes can't disturb other
9622 Defaults to @samp{"dovecot"}.
9625 @deftypevr {@code{dovecot-configuration} parameter} string ssl?
9626 SSL/TLS support: yes, no, required. <doc/wiki/SSL.txt>.
9627 Defaults to @samp{"required"}.
9630 @deftypevr {@code{dovecot-configuration} parameter} string ssl-cert
9631 PEM encoded X.509 SSL/TLS certificate (public key).
9632 Defaults to @samp{"</etc/dovecot/default.pem"}.
9635 @deftypevr {@code{dovecot-configuration} parameter} string ssl-key
9636 PEM encoded SSL/TLS private key. The key is opened before
9637 dropping root privileges, so keep the key file unreadable by anyone but
9639 Defaults to @samp{"</etc/dovecot/private/default.pem"}.
9642 @deftypevr {@code{dovecot-configuration} parameter} string ssl-key-password
9643 If key file is password protected, give the password here.
9644 Alternatively give it when starting dovecot with -p parameter. Since
9645 this file is often world-readable, you may want to place this setting
9646 instead to a different.
9647 Defaults to @samp{""}.
9650 @deftypevr {@code{dovecot-configuration} parameter} string ssl-ca
9651 PEM encoded trusted certificate authority. Set this only if you
9652 intend to use @samp{ssl-verify-client-cert? #t}. The file should
9653 contain the CA certificate(s) followed by the matching
9654 CRL(s). (e.g. @samp{ssl-ca </etc/ssl/certs/ca.pem}).
9655 Defaults to @samp{""}.
9658 @deftypevr {@code{dovecot-configuration} parameter} boolean ssl-require-crl?
9659 Require that CRL check succeeds for client certificates.
9660 Defaults to @samp{#t}.
9663 @deftypevr {@code{dovecot-configuration} parameter} boolean ssl-verify-client-cert?
9664 Request client to send a certificate. If you also want to require
9665 it, set @samp{auth-ssl-require-client-cert? #t} in auth section.
9666 Defaults to @samp{#f}.
9669 @deftypevr {@code{dovecot-configuration} parameter} string ssl-cert-username-field
9670 Which field from certificate to use for username. commonName and
9671 x500UniqueIdentifier are the usual choices. You'll also need to set
9672 @samp{auth-ssl-username-from-cert? #t}.
9673 Defaults to @samp{"commonName"}.
9676 @deftypevr {@code{dovecot-configuration} parameter} hours ssl-parameters-regenerate
9677 How often to regenerate the SSL parameters file. Generation is
9678 quite CPU intensive operation. The value is in hours, 0 disables
9679 regeneration entirely.
9680 Defaults to @samp{168}.
9683 @deftypevr {@code{dovecot-configuration} parameter} string ssl-protocols
9684 SSL protocols to use.
9685 Defaults to @samp{"!SSLv2"}.
9688 @deftypevr {@code{dovecot-configuration} parameter} string ssl-cipher-list
9690 Defaults to @samp{"ALL:!LOW:!SSLv2:!EXP:!aNULL"}.
9693 @deftypevr {@code{dovecot-configuration} parameter} string ssl-crypto-device
9694 SSL crypto device to use, for valid values run "openssl engine".
9695 Defaults to @samp{""}.
9698 @deftypevr {@code{dovecot-configuration} parameter} string postmaster-address
9699 Address to use when sending rejection mails.
9700 Default is postmaster@@<your domain>. %d expands to recipient domain.
9701 Defaults to @samp{""}.
9704 @deftypevr {@code{dovecot-configuration} parameter} string hostname
9705 Hostname to use in various parts of sent mails (e.g. in Message-Id)
9706 and in LMTP replies. Default is the system's real hostname@@domain.
9707 Defaults to @samp{""}.
9710 @deftypevr {@code{dovecot-configuration} parameter} boolean quota-full-tempfail?
9711 If user is over quota, return with temporary failure instead of
9713 Defaults to @samp{#f}.
9716 @deftypevr {@code{dovecot-configuration} parameter} file-name sendmail-path
9717 Binary to use for sending mails.
9718 Defaults to @samp{"/usr/sbin/sendmail"}.
9721 @deftypevr {@code{dovecot-configuration} parameter} string submission-host
9722 If non-empty, send mails via this SMTP host[:port] instead of
9724 Defaults to @samp{""}.
9727 @deftypevr {@code{dovecot-configuration} parameter} string rejection-subject
9728 Subject: header to use for rejection mails. You can use the same
9729 variables as for @samp{rejection-reason} below.
9730 Defaults to @samp{"Rejected: %s"}.
9733 @deftypevr {@code{dovecot-configuration} parameter} string rejection-reason
9734 Human readable error message for rejection mails. You can use
9747 Defaults to @samp{"Your message to <%t> was automatically rejected:%n%r"}.
9750 @deftypevr {@code{dovecot-configuration} parameter} string recipient-delimiter
9751 Delimiter character between local-part and detail in email
9753 Defaults to @samp{"+"}.
9756 @deftypevr {@code{dovecot-configuration} parameter} string lda-original-recipient-header
9757 Header where the original recipient address (SMTP's RCPT TO:
9758 address) is taken from if not available elsewhere. With dovecot-lda -a
9759 parameter overrides this. A commonly used header for this is
9761 Defaults to @samp{""}.
9764 @deftypevr {@code{dovecot-configuration} parameter} boolean lda-mailbox-autocreate?
9765 Should saving a mail to a nonexistent mailbox automatically create
9767 Defaults to @samp{#f}.
9770 @deftypevr {@code{dovecot-configuration} parameter} boolean lda-mailbox-autosubscribe?
9771 Should automatically created mailboxes be also automatically
9773 Defaults to @samp{#f}.
9776 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer imap-max-line-length
9777 Maximum IMAP command line length. Some clients generate very long
9778 command lines with huge mailboxes, so you may need to raise this if you
9779 get "Too long argument" or "IMAP command line too large" errors
9781 Defaults to @samp{64000}.
9784 @deftypevr {@code{dovecot-configuration} parameter} string imap-logout-format
9785 IMAP logout format string:
9788 total number of bytes read from client
9790 total number of bytes sent to client.
9792 Defaults to @samp{"in=%i out=%o"}.
9795 @deftypevr {@code{dovecot-configuration} parameter} string imap-capability
9796 Override the IMAP CAPABILITY response. If the value begins with '+',
9797 add the given capabilities on top of the defaults (e.g. +XFOO XBAR).
9798 Defaults to @samp{""}.
9801 @deftypevr {@code{dovecot-configuration} parameter} string imap-idle-notify-interval
9802 How long to wait between "OK Still here" notifications when client
9804 Defaults to @samp{"2 mins"}.
9807 @deftypevr {@code{dovecot-configuration} parameter} string imap-id-send
9808 ID field names and values to send to clients. Using * as the value
9809 makes Dovecot use the default value. The following fields have default
9810 values currently: name, version, os, os-version, support-url,
9812 Defaults to @samp{""}.
9815 @deftypevr {@code{dovecot-configuration} parameter} string imap-id-log
9816 ID fields sent by client to log. * means everything.
9817 Defaults to @samp{""}.
9820 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list imap-client-workarounds
9821 Workarounds for various client bugs:
9825 Send EXISTS/RECENT new mail notifications only when replying to NOOP and
9826 CHECK commands. Some clients ignore them otherwise, for example OSX
9827 Mail (<v2.1). Outlook Express breaks more badly though, without this it
9828 may show user "Message no longer in server" errors. Note that OE6
9829 still breaks even with this workaround if synchronization is set to
9832 @item tb-extra-mailbox-sep
9833 Thunderbird gets somehow confused with LAYOUT=fs (mbox and dbox) and
9834 adds extra @samp{/} suffixes to mailbox names. This option causes Dovecot to
9835 ignore the extra @samp{/} instead of treating it as invalid mailbox name.
9838 Show \Noselect flags for LSUB replies with LAYOUT=fs (e.g. mbox).
9839 This makes Thunderbird realize they aren't selectable and show them
9840 greyed out, instead of only later giving "not selectable" popup error.
9842 Defaults to @samp{()}.
9845 @deftypevr {@code{dovecot-configuration} parameter} string imap-urlauth-host
9846 Host allowed in URLAUTH URLs sent by client. "*" allows all.
9847 Defaults to @samp{""}.
9851 Whew! Lots of configuration options. The nice thing about it though is
9852 that GuixSD has a complete interface to Dovecot's configuration
9853 language. This allows not only a nice way to declare configurations,
9854 but also offers reflective capabilities as well: users can write code to
9855 inspect and transform configurations from within Scheme.
9857 However, it could be that you just want to get a @code{dovecot.conf} up
9858 and running. In that case, you can pass an
9859 @code{opaque-dovecot-configuration} as the @code{#:config} paramter to
9860 @code{dovecot-service}. As its name indicates, an opaque configuration
9861 does not have easy reflective capabilities.
9863 Available @code{opaque-dovecot-configuration} fields are:
9865 @deftypevr {@code{opaque-dovecot-configuration} parameter} package dovecot
9866 The dovecot package.
9869 @deftypevr {@code{opaque-dovecot-configuration} parameter} string string
9870 The contents of the @code{dovecot.conf}, as a string.
9873 For example, if your @code{dovecot.conf} is just the empty string, you
9874 could instantiate a dovecot service like this:
9877 (dovecot-service #:config
9878 (opaque-dovecot-configuration
9883 @subsubsection Web Services
9885 The @code{(gnu services web)} module provides the following service:
9887 @deffn {Scheme Procedure} nginx-service [#:nginx nginx] @
9888 [#:log-directory ``/var/log/nginx''] @
9889 [#:run-directory ``/var/run/nginx''] @
9892 Return a service that runs @var{nginx}, the nginx web server.
9894 The nginx daemon loads its runtime configuration from @var{config-file}.
9895 Log files are written to @var{log-directory} and temporary runtime data
9896 files are written to @var{run-directory}. For proper operation, these
9897 arguments should match what is in @var{config-file} to ensure that the
9898 directories are created when the service is activated.
9902 @node Various Services
9903 @subsubsection Various Services
9906 @subsubheading Lirc Service
9908 The @code{(gnu services lirc)} module provides the following service.
9910 @deffn {Scheme Procedure} lirc-service [#:lirc lirc] @
9911 [#:device #f] [#:driver #f] [#:config-file #f] @
9912 [#:extra-options '()]
9913 Return a service that runs @url{http://www.lirc.org,LIRC}, a daemon that
9914 decodes infrared signals from remote controls.
9916 Optionally, @var{device}, @var{driver} and @var{config-file}
9917 (configuration file name) may be specified. See @command{lircd} manual
9920 Finally, @var{extra-options} is a list of additional command-line options
9921 passed to @command{lircd}.
9924 @subsubsection Dictionary Services
9925 The @code{(gnu services dict)} module provides the following service:
9927 @deffn {Scheme Procedure} dicod-service [#:config (dicod-configuration)]
9928 Return a service that runs the @command{dicod} daemon, an implementation
9929 of DICT server (@pxref{Dicod,,, dico, GNU Dico Manual}).
9931 The optional @var{config} argument specifies the configuration for
9932 @command{dicod}, which should be a @code{<dicod-configuration>} object, by
9933 default it serves the GNU Collaborative International Dictonary of English.
9935 You can add @command{open localhost} to your @file{~/.dico} file to make
9936 @code{localhost} the default server for @command{dico} client
9937 (@pxref{Initialization File,,, dico, GNU Dico Manual}).
9940 @deftp {Data Type} dicod-configuration
9941 Data type representing the configuration of dicod.
9944 @item @code{dico} (default: @var{dico})
9945 Package object of the GNU Dico dictionary server.
9947 @item @code{interfaces} (default: @var{'("localhost")})
9948 This is the list of IP addresses and ports and possibly socket file
9949 names to listen to (@pxref{Server Settings, @code{listen} directive,,
9950 dico, GNU Dico Manual}).
9952 @item @code{databases} (default: @var{(list %dicod-database:gcide)})
9953 List of @code{<dicod-database>} objects denoting dictionaries to be served.
9957 @deftp {Data Type} dicod-database
9958 Data type representing a dictionary database.
9962 Name of the database, will be used in DICT commands.
9965 Name of the dicod module used by this database
9966 (@pxref{Modules,,, dico, GNU Dico Manual}).
9968 @item @code{options}
9969 List of strings or gexps representing the arguments for the module handler
9970 (@pxref{Handlers,,, dico, GNU Dico Manual}).
9974 @defvr {Scheme Variable} %dicod-database:gcide
9975 A @code{<dicod-database>} object serving the GNU Collaborative International
9976 Dictonary of English using the @code{gcide} package.
9979 @node Setuid Programs
9980 @subsection Setuid Programs
9982 @cindex setuid programs
9983 Some programs need to run with ``root'' privileges, even when they are
9984 launched by unprivileged users. A notorious example is the
9985 @command{passwd} program, which users can run to change their
9986 password, and which needs to access the @file{/etc/passwd} and
9987 @file{/etc/shadow} files---something normally restricted to root, for
9988 obvious security reasons. To address that, these executables are
9989 @dfn{setuid-root}, meaning that they always run with root privileges
9990 (@pxref{How Change Persona,,, libc, The GNU C Library Reference Manual},
9991 for more info about the setuid mechanism.)
9993 The store itself @emph{cannot} contain setuid programs: that would be a
9994 security issue since any user on the system can write derivations that
9995 populate the store (@pxref{The Store}). Thus, a different mechanism is
9996 used: instead of changing the setuid bit directly on files that are in
9997 the store, we let the system administrator @emph{declare} which programs
9998 should be setuid root.
10000 The @code{setuid-programs} field of an @code{operating-system}
10001 declaration contains a list of G-expressions denoting the names of
10002 programs to be setuid-root (@pxref{Using the Configuration System}).
10003 For instance, the @command{passwd} program, which is part of the Shadow
10004 package, can be designated by this G-expression (@pxref{G-Expressions}):
10007 #~(string-append #$shadow "/bin/passwd")
10010 A default set of setuid programs is defined by the
10011 @code{%setuid-programs} variable of the @code{(gnu system)} module.
10013 @defvr {Scheme Variable} %setuid-programs
10014 A list of G-expressions denoting common programs that are setuid-root.
10016 The list includes commands such as @command{passwd}, @command{ping},
10017 @command{su}, and @command{sudo}.
10020 Under the hood, the actual setuid programs are created in the
10021 @file{/run/setuid-programs} directory at system activation time. The
10022 files in this directory refer to the ``real'' binaries, which are in the
10025 @node X.509 Certificates
10026 @subsection X.509 Certificates
10028 @cindex HTTPS, certificates
10029 @cindex X.509 certificates
10031 Web servers available over HTTPS (that is, HTTP over the transport-layer
10032 security mechanism, TLS) send client programs an @dfn{X.509 certificate}
10033 that the client can then use to @emph{authenticate} the server. To do
10034 that, clients verify that the server's certificate is signed by a
10035 so-called @dfn{certificate authority} (CA). But to verify the CA's
10036 signature, clients must have first acquired the CA's certificate.
10038 Web browsers such as GNU@tie{}IceCat include their own set of CA
10039 certificates, such that they are able to verify CA signatures
10042 However, most other programs that can talk HTTPS---@command{wget},
10043 @command{git}, @command{w3m}, etc.---need to be told where CA
10044 certificates can be found.
10046 @cindex @code{nss-certs}
10047 In GuixSD, this is done by adding a package that provides certificates
10048 to the @code{packages} field of the @code{operating-system} declaration
10049 (@pxref{operating-system Reference}). GuixSD includes one such package,
10050 @code{nss-certs}, which is a set of CA certificates provided as part of
10051 Mozilla's Network Security Services.
10053 Note that it is @emph{not} part of @var{%base-packages}, so you need to
10054 explicitly add it. The @file{/etc/ssl/certs} directory, which is where
10055 most applications and libraries look for certificates by default, points
10056 to the certificates installed globally.
10058 Unprivileged users, including users of Guix on a foreign distro,
10059 can also install their own certificate package in
10060 their profile. A number of environment variables need to be defined so
10061 that applications and libraries know where to find them. Namely, the
10062 OpenSSL library honors the @code{SSL_CERT_DIR} and @code{SSL_CERT_FILE}
10063 variables. Some applications add their own environment variables; for
10064 instance, the Git version control system honors the certificate bundle
10065 pointed to by the @code{GIT_SSL_CAINFO} environment variable. Thus, you
10066 would typically run something like:
10069 $ guix package -i nss-certs
10070 $ export SSL_CERT_DIR="$HOME/.guix-profile/etc/ssl/certs"
10071 $ export SSL_CERT_FILE="$HOME/.guix-profile/etc/ssl/certs/ca-certificates.crt"
10072 $ export GIT_SSL_CAINFO="$SSL_CERT_FILE"
10075 @node Name Service Switch
10076 @subsection Name Service Switch
10078 @cindex name service switch
10080 The @code{(gnu system nss)} module provides bindings to the
10081 configuration file of the libc @dfn{name service switch} or @dfn{NSS}
10082 (@pxref{NSS Configuration File,,, libc, The GNU C Library Reference
10083 Manual}). In a nutshell, the NSS is a mechanism that allows libc to be
10084 extended with new ``name'' lookup methods for system databases, which
10085 includes host names, service names, user accounts, and more (@pxref{Name
10086 Service Switch, System Databases and Name Service Switch,, libc, The GNU
10087 C Library Reference Manual}).
10089 The NSS configuration specifies, for each system database, which lookup
10090 method is to be used, and how the various methods are chained
10091 together---for instance, under which circumstances NSS should try the
10092 next method in the list. The NSS configuration is given in the
10093 @code{name-service-switch} field of @code{operating-system} declarations
10094 (@pxref{operating-system Reference, @code{name-service-switch}}).
10097 @cindex .local, host name lookup
10098 As an example, the declaration below configures the NSS to use the
10099 @uref{http://0pointer.de/lennart/projects/nss-mdns/, @code{nss-mdns}
10100 back-end}, which supports host name lookups over multicast DNS (mDNS)
10101 for host names ending in @code{.local}:
10104 (name-service-switch
10105 (hosts (list %files ;first, check /etc/hosts
10107 ;; If the above did not succeed, try
10108 ;; with 'mdns_minimal'.
10110 (name "mdns_minimal")
10112 ;; 'mdns_minimal' is authoritative for
10113 ;; '.local'. When it returns "not found",
10114 ;; no need to try the next methods.
10115 (reaction (lookup-specification
10116 (not-found => return))))
10118 ;; Then fall back to DNS.
10122 ;; Finally, try with the "full" 'mdns'.
10127 Do not worry: the @code{%mdns-host-lookup-nss} variable (see below)
10128 contains this configuration, so you will not have to type it if all you
10129 want is to have @code{.local} host lookup working.
10131 Note that, in this case, in addition to setting the
10132 @code{name-service-switch} of the @code{operating-system} declaration,
10133 you also need to use @code{avahi-service} (@pxref{Networking Services,
10134 @code{avahi-service}}), or @var{%desktop-services}, which includes it
10135 (@pxref{Desktop Services}). Doing this makes @code{nss-mdns} accessible
10136 to the name service cache daemon (@pxref{Base Services,
10137 @code{nscd-service}}).
10139 For convenience, the following variables provide typical NSS
10142 @defvr {Scheme Variable} %default-nss
10143 This is the default name service switch configuration, a
10144 @code{name-service-switch} object.
10147 @defvr {Scheme Variable} %mdns-host-lookup-nss
10148 This is the name service switch configuration with support for host name
10149 lookup over multicast DNS (mDNS) for host names ending in @code{.local}.
10152 The reference for name service switch configuration is given below. It
10153 is a direct mapping of the configuration file format of the C library , so
10154 please refer to the C library manual for more information (@pxref{NSS
10155 Configuration File,,, libc, The GNU C Library Reference Manual}).
10156 Compared to the configuration file format of libc NSS, it has the advantage
10157 not only of adding this warm parenthetic feel that we like, but also
10158 static checks: you will know about syntax errors and typos as soon as you
10159 run @command{guix system}.
10161 @deftp {Data Type} name-service-switch
10163 This is the data type representation the configuration of libc's name
10164 service switch (NSS). Each field below represents one of the supported
10181 The system databases handled by the NSS. Each of these fields must be a
10182 list of @code{<name-service>} objects (see below).
10186 @deftp {Data Type} name-service
10188 This is the data type representing an actual name service and the
10189 associated lookup action.
10193 A string denoting the name service (@pxref{Services in the NSS
10194 configuration,,, libc, The GNU C Library Reference Manual}).
10196 Note that name services listed here must be visible to nscd. This is
10197 achieved by passing the @code{#:name-services} argument to
10198 @code{nscd-service} the list of packages providing the needed name
10199 services (@pxref{Base Services, @code{nscd-service}}).
10202 An action specified using the @code{lookup-specification} macro
10203 (@pxref{Actions in the NSS configuration,,, libc, The GNU C Library
10204 Reference Manual}). For example:
10207 (lookup-specification (unavailable => continue)
10208 (success => return))
10213 @node Initial RAM Disk
10214 @subsection Initial RAM Disk
10216 @cindex initial RAM disk (initrd)
10217 @cindex initrd (initial RAM disk)
10218 For bootstrapping purposes, the Linux-Libre kernel is passed an
10219 @dfn{initial RAM disk}, or @dfn{initrd}. An initrd contains a temporary
10220 root file system as well as an initialization script. The latter is
10221 responsible for mounting the real root file system, and for loading any
10222 kernel modules that may be needed to achieve that.
10224 The @code{initrd} field of an @code{operating-system} declaration allows
10225 you to specify which initrd you would like to use. The @code{(gnu
10226 system linux-initrd)} module provides two ways to build an initrd: the
10227 high-level @code{base-initrd} procedure, and the low-level
10228 @code{expression->initrd} procedure.
10230 The @code{base-initrd} procedure is intended to cover most common uses.
10231 For example, if you want to add a bunch of kernel modules to be loaded
10232 at boot time, you can define the @code{initrd} field of the operating
10233 system declaration like this:
10236 (initrd (lambda (file-systems . rest)
10237 ;; Create a standard initrd that has modules "foo.ko"
10238 ;; and "bar.ko", as well as their dependencies, in
10239 ;; addition to the modules available by default.
10240 (apply base-initrd file-systems
10241 #:extra-modules '("foo" "bar")
10245 The @code{base-initrd} procedure also handles common use cases that
10246 involves using the system as a QEMU guest, or as a ``live'' system with
10247 volatile root file system.
10249 The initial RAM disk produced by @code{base-initrd} honors several
10250 options passed on the Linux kernel command line (that is, arguments
10251 passed @i{via} the @code{linux} command of GRUB, or the
10252 @code{-append} option) of QEMU, notably:
10255 @item --load=@var{boot}
10256 Tell the initial RAM disk to load @var{boot}, a file containing a Scheme
10257 program, once it has mounted the root file system.
10259 GuixSD uses this option to yield control to a boot program that runs the
10260 service activation programs and then spawns the GNU@tie{}Shepherd, the
10261 initialization system.
10263 @item --root=@var{root}
10264 Mount @var{root} as the root file system. @var{root} can be a
10265 device name like @code{/dev/sda1}, a partition label, or a partition
10268 @item --system=@var{system}
10269 Have @file{/run/booted-system} and @file{/run/current-system} point to
10272 @item modprobe.blacklist=@var{modules}@dots{}
10273 @cindex module, black-listing
10274 @cindex black list, of kernel modules
10275 Instruct the initial RAM disk as well as the @command{modprobe} command
10276 (from the kmod package) to refuse to load @var{modules}. @var{modules}
10277 must be a comma-separated list of module names---e.g.,
10278 @code{usbkbd,9pnet}.
10281 Start a read-eval-print loop (REPL) from the initial RAM disk before it
10282 tries to load kernel modules and to mount the root file system. Our
10283 marketing team calls it @dfn{boot-to-Guile}. The Schemer in you will
10284 love it. @xref{Using Guile Interactively,,, guile, GNU Guile Reference
10285 Manual}, for more information on Guile's REPL.
10289 Now that you know all the features that initial RAM disks produced by
10290 @code{base-initrd} provide, here is how to use it and customize it
10293 @deffn {Monadic Procedure} base-initrd @var{file-systems} @
10294 [#:qemu-networking? #f] [#:virtio? #t] [#:volatile-root? #f] @
10295 [#:extra-modules '()] [#:mapped-devices '()]
10296 Return a monadic derivation that builds a generic initrd. @var{file-systems} is
10297 a list of file systems to be mounted by the initrd, possibly in addition to
10298 the root file system specified on the kernel command line via @code{--root}.
10299 @var{mapped-devices} is a list of device mappings to realize before
10300 @var{file-systems} are mounted (@pxref{Mapped Devices}).
10302 When @var{qemu-networking?} is true, set up networking with the standard QEMU
10303 parameters. When @var{virtio?} is true, load additional modules so that the
10304 initrd can be used as a QEMU guest with para-virtualized I/O drivers.
10306 When @var{volatile-root?} is true, the root file system is writable but any changes
10309 The initrd is automatically populated with all the kernel modules necessary
10310 for @var{file-systems} and for the given options. However, additional kernel
10311 modules can be listed in @var{extra-modules}. They will be added to the initrd, and
10312 loaded at boot time in the order in which they appear.
10315 Needless to say, the initrds we produce and use embed a
10316 statically-linked Guile, and the initialization program is a Guile
10317 program. That gives a lot of flexibility. The
10318 @code{expression->initrd} procedure builds such an initrd, given the
10319 program to run in that initrd.
10321 @deffn {Monadic Procedure} expression->initrd @var{exp} @
10322 [#:guile %guile-static-stripped] [#:name "guile-initrd"]
10323 Return a derivation that builds a Linux initrd (a gzipped cpio archive)
10324 containing @var{guile} and that evaluates @var{exp}, a G-expression,
10325 upon booting. All the derivations referenced by @var{exp} are
10326 automatically copied to the initrd.
10329 @node GRUB Configuration
10330 @subsection GRUB Configuration
10333 @cindex boot loader
10335 The operating system uses GNU@tie{}GRUB as its boot loader
10336 (@pxref{Overview, overview of GRUB,, grub, GNU GRUB Manual}). It is
10337 configured using a @code{grub-configuration} declaration. This data type
10338 is exported by the @code{(gnu system grub)} module and described below.
10340 @deftp {Data Type} grub-configuration
10341 The type of a GRUB configuration declaration.
10345 @item @code{device}
10346 This is a string denoting the boot device. It must be a device name
10347 understood by the @command{grub-install} command, such as
10348 @code{/dev/sda} or @code{(hd0)} (@pxref{Invoking grub-install,,, grub,
10351 @item @code{menu-entries} (default: @code{()})
10352 A possibly empty list of @code{menu-entry} objects (see below), denoting
10353 entries to appear in the GRUB boot menu, in addition to the current
10354 system entry and the entry pointing to previous system generations.
10356 @item @code{default-entry} (default: @code{0})
10357 The index of the default boot menu entry. Index 0 is for the entry of the
10360 @item @code{timeout} (default: @code{5})
10361 The number of seconds to wait for keyboard input before booting. Set to
10362 0 to boot immediately, and to -1 to wait indefinitely.
10364 @item @code{theme} (default: @var{%default-theme})
10365 The @code{grub-theme} object describing the theme to use.
10370 Should you want to list additional boot menu entries @i{via} the
10371 @code{menu-entries} field above, you will need to create them with the
10372 @code{menu-entry} form:
10374 @deftp {Data Type} menu-entry
10375 The type of an entry in the GRUB boot menu.
10380 The label to show in the menu---e.g., @code{"GNU"}.
10383 The Linux kernel to boot.
10385 @item @code{linux-arguments} (default: @code{()})
10386 The list of extra Linux kernel command-line arguments---e.g.,
10387 @code{("console=ttyS0")}.
10389 @item @code{initrd}
10390 A G-Expression or string denoting the file name of the initial RAM disk
10391 to use (@pxref{G-Expressions}).
10396 @c FIXME: Write documentation once it's stable.
10397 Themes are created using the @code{grub-theme} form, which is not
10400 @defvr {Scheme Variable} %default-theme
10401 This is the default GRUB theme used by the operating system, with a
10402 fancy background image displaying the GNU and Guix logos.
10406 @node Invoking guix system
10407 @subsection Invoking @code{guix system}
10409 Once you have written an operating system declaration as seen in the
10410 previous section, it can be @dfn{instantiated} using the @command{guix
10411 system} command. The synopsis is:
10414 guix system @var{options}@dots{} @var{action} @var{file}
10417 @var{file} must be the name of a file containing an
10418 @code{operating-system} declaration. @var{action} specifies how the
10419 operating system is instantiated. Currently the following values are
10424 Build the operating system described in @var{file}, activate it, and
10425 switch to it@footnote{This action is usable only on systems already
10428 This effects all the configuration specified in @var{file}: user
10429 accounts, system services, global package list, setuid programs, etc.
10430 The command starts system services specified in @var{file} that are not
10431 currently running; if a service is currently running, it does not
10432 attempt to upgrade it since this would not be possible without stopping it
10435 It also adds a GRUB menu entry for the new OS configuration, and moves
10436 entries for older configurations to a submenu---unless
10437 @option{--no-grub} is passed.
10440 @c The paragraph below refers to the problem discussed at
10441 @c <http://lists.gnu.org/archive/html/guix-devel/2014-08/msg00057.html>.
10442 It is highly recommended to run @command{guix pull} once before you run
10443 @command{guix system reconfigure} for the first time (@pxref{Invoking
10444 guix pull}). Failing to do that you would see an older version of Guix
10445 once @command{reconfigure} has completed.
10449 Build the derivation of the operating system, which includes all the
10450 configuration files and programs needed to boot and run the system.
10451 This action does not actually install anything.
10454 Populate the given directory with all the files necessary to run the
10455 operating system specified in @var{file}. This is useful for first-time
10456 installations of GuixSD. For instance:
10459 guix system init my-os-config.scm /mnt
10462 copies to @file{/mnt} all the store items required by the configuration
10463 specified in @file{my-os-config.scm}. This includes configuration
10464 files, packages, and so on. It also creates other essential files
10465 needed for the system to operate correctly---e.g., the @file{/etc},
10466 @file{/var}, and @file{/run} directories, and the @file{/bin/sh} file.
10468 This command also installs GRUB on the device specified in
10469 @file{my-os-config}, unless the @option{--no-grub} option was passed.
10472 @cindex virtual machine
10474 @anchor{guix system vm}
10475 Build a virtual machine that contains the operating system declared in
10476 @var{file}, and return a script to run that virtual machine (VM).
10477 Arguments given to the script are passed to QEMU.
10479 The VM shares its store with the host system.
10481 Additional file systems can be shared between the host and the VM using
10482 the @code{--share} and @code{--expose} command-line options: the former
10483 specifies a directory to be shared with write access, while the latter
10484 provides read-only access to the shared directory.
10486 The example below creates a VM in which the user's home directory is
10487 accessible read-only, and where the @file{/exchange} directory is a
10488 read-write mapping of @file{$HOME/tmp} on the host:
10491 guix system vm my-config.scm \
10492 --expose=$HOME --share=$HOME/tmp=/exchange
10495 On GNU/Linux, the default is to boot directly to the kernel; this has
10496 the advantage of requiring only a very tiny root disk image since the
10497 store of the host can then be mounted.
10499 The @code{--full-boot} option forces a complete boot sequence, starting
10500 with the bootloader. This requires more disk space since a root image
10501 containing at least the kernel, initrd, and bootloader data files must
10502 be created. The @code{--image-size} option can be used to specify the
10507 Return a virtual machine or disk image of the operating system declared
10508 in @var{file} that stands alone. Use the @option{--image-size} option
10509 to specify the size of the image.
10511 When using @code{vm-image}, the returned image is in qcow2 format, which
10512 the QEMU emulator can efficiently use. @xref{Running GuixSD in a VM},
10513 for more information on how to run the image in a virtual machine.
10515 When using @code{disk-image}, a raw disk image is produced; it can be
10516 copied as is to a USB stick, for instance. Assuming @code{/dev/sdc} is
10517 the device corresponding to a USB stick, one can copy the image to it
10518 using the following command:
10521 # dd if=$(guix system disk-image my-os.scm) of=/dev/sdc
10525 Return a script to run the operating system declared in @var{file}
10526 within a container. Containers are a set of lightweight isolation
10527 mechanisms provided by the kernel Linux-libre. Containers are
10528 substantially less resource-demanding than full virtual machines since
10529 the kernel, shared objects, and other resources can be shared with the
10530 host system; this also means they provide thinner isolation.
10532 Currently, the script must be run as root in order to support more than
10533 a single user and group. The container shares its store with the host
10536 As with the @code{vm} action (@pxref{guix system vm}), additional file
10537 systems to be shared between the host and container can be specified
10538 using the @option{--share} and @option{--expose} options:
10541 guix system container my-config.scm \
10542 --expose=$HOME --share=$HOME/tmp=/exchange
10546 This option requires Linux-libre 3.19 or newer.
10551 @var{options} can contain any of the common build options (@pxref{Common
10552 Build Options}). In addition, @var{options} can contain one of the
10556 @item --system=@var{system}
10557 @itemx -s @var{system}
10558 Attempt to build for @var{system} instead of the host system type.
10559 This works as per @command{guix build} (@pxref{Invoking guix build}).
10563 Return the derivation file name of the given operating system without
10566 @item --image-size=@var{size}
10567 For the @code{vm-image} and @code{disk-image} actions, create an image
10568 of the given @var{size}. @var{size} may be a number of bytes, or it may
10569 include a unit as a suffix (@pxref{Block size, size specifications,,
10570 coreutils, GNU Coreutils}).
10572 @item --on-error=@var{strategy}
10573 Apply @var{strategy} when an error occurs when reading @var{file}.
10574 @var{strategy} may be one of the following:
10577 @item nothing-special
10578 Report the error concisely and exit. This is the default strategy.
10581 Likewise, but also display a backtrace.
10584 Report the error and enter Guile's debugger. From there, you can run
10585 commands such as @code{,bt} to get a backtrace, @code{,locals} to
10586 display local variable values, and more generally inspect the state of the
10587 program. @xref{Debug Commands,,, guile, GNU Guile Reference Manual}, for
10588 a list of available debugging commands.
10593 All the actions above, except @code{build} and @code{init},
10594 can use KVM support in the Linux-libre kernel. Specifically, if the
10595 machine has hardware virtualization support, the corresponding
10596 KVM kernel module should be loaded, and the @file{/dev/kvm} device node
10597 must exist and be readable and writable by the user and by the
10598 build users of the daemon (@pxref{Build Environment Setup}).
10601 Once you have built, configured, re-configured, and re-re-configured
10602 your GuixSD installation, you may find it useful to list the operating
10603 system generations available on disk---and that you can choose from the
10608 @item list-generations
10609 List a summary of each generation of the operating system available on
10610 disk, in a human-readable way. This is similar to the
10611 @option{--list-generations} option of @command{guix package}
10612 (@pxref{Invoking guix package}).
10614 Optionally, one can specify a pattern, with the same syntax that is used
10615 in @command{guix package --list-generations}, to restrict the list of
10616 generations displayed. For instance, the following command displays
10617 generations that are up to 10 days old:
10620 $ guix system list-generations 10d
10625 The @command{guix system} command has even more to offer! The following
10626 sub-commands allow you to visualize how your system services relate to
10629 @anchor{system-extension-graph}
10632 @item extension-graph
10633 Emit in Dot/Graphviz format to standard output the @dfn{service
10634 extension graph} of the operating system defined in @var{file}
10635 (@pxref{Service Composition}, for more information on service
10641 $ guix system extension-graph @var{file} | dot -Tpdf > services.pdf
10644 produces a PDF file showing the extension relations among services.
10646 @anchor{system-shepherd-graph}
10647 @item shepherd-graph
10648 Emit in Dot/Graphviz format to standard output the @dfn{dependency
10649 graph} of shepherd services of the operating system defined in
10650 @var{file}. @xref{Shepherd Services}, for more information and for an
10655 @node Running GuixSD in a VM
10656 @subsection Running GuixSD in a Virtual Machine
10658 One way to run GuixSD in a virtual machine (VM) is to build a GuixSD
10659 virtual machine image using @command{guix system vm-image}
10660 (@pxref{Invoking guix system}). The returned image is in qcow2 format,
10661 which the @uref{http://qemu.org/, QEMU emulator} can efficiently use.
10663 To run the image in QEMU, copy it out of the store (@pxref{The Store})
10664 and give yourself permission to write to the copy. When invoking QEMU,
10665 you must choose a system emulator that is suitable for your hardware
10666 platform. Here is a minimal QEMU invocation that will boot the result
10667 of @command{guix system vm-image} on x86_64 hardware:
10670 $ qemu-system-x86_64 \
10671 -net user -net nic,model=virtio \
10672 -enable-kvm -m 256 /tmp/qemu-image
10675 Here is what each of these options means:
10678 @item qemu-system-x86_64
10679 This specifies the hardware platform to emulate. This should match the
10683 Enable the unprivileged user-mode network stack. The guest OS can
10684 access the host but not vice versa. This is the simplest way to get the
10685 guest OS online. If you do not choose a network stack, the boot will
10688 @item -net nic,model=virtio
10689 You must create a network interface of a given model. If you do not
10690 create a NIC, the boot will fail. Assuming your hardware platform is
10691 x86_64, you can get a list of available NIC models by running
10692 @command{qemu-system-x86_64 -net nic,model=help}.
10695 If your system has hardware virtualization extensions, enabling the
10696 virtual machine support (KVM) of the Linux kernel will make things run
10700 RAM available to the guest OS, in mebibytes. Defaults to 128@tie{}MiB,
10701 which may be insufficent for some operations.
10703 @item /tmp/qemu-image
10704 The file name of the qcow2 image.
10707 @node Defining Services
10708 @subsection Defining Services
10710 The previous sections show the available services and how one can combine
10711 them in an @code{operating-system} declaration. But how do we define
10712 them in the first place? And what is a service anyway?
10715 * Service Composition:: The model for composing services.
10716 * Service Types and Services:: Types and services.
10717 * Service Reference:: API reference.
10718 * Shepherd Services:: A particular type of service.
10721 @node Service Composition
10722 @subsubsection Service Composition
10726 Here we define a @dfn{service} as, broadly, something that extends the
10727 functionality of the operating system. Often a service is a process---a
10728 @dfn{daemon}---started when the system boots: a secure shell server, a
10729 Web server, the Guix build daemon, etc. Sometimes a service is a daemon
10730 whose execution can be triggered by another daemon---e.g., an FTP server
10731 started by @command{inetd} or a D-Bus service activated by
10732 @command{dbus-daemon}. Occasionally, a service does not map to a
10733 daemon. For instance, the ``account'' service collects user accounts
10734 and makes sure they exist when the system runs; the ``udev'' service
10735 collects device management rules and makes them available to the eudev
10736 daemon; the @file{/etc} service populates the @file{/etc} directory
10739 @cindex service extensions
10740 GuixSD services are connected by @dfn{extensions}. For instance, the
10741 secure shell service @emph{extends} the Shepherd---the GuixSD
10742 initialization system, running as PID@tie{}1---by giving it the command
10743 lines to start and stop the secure shell daemon (@pxref{Networking
10744 Services, @code{lsh-service}}); the UPower service extends the D-Bus
10745 service by passing it its @file{.service} specification, and extends the
10746 udev service by passing it device management rules (@pxref{Desktop
10747 Services, @code{upower-service}}); the Guix daemon service extends the
10748 Shepherd by passing it the command lines to start and stop the daemon,
10749 and extends the account service by passing it a list of required build
10750 user accounts (@pxref{Base Services}).
10752 All in all, services and their ``extends'' relations form a directed
10753 acyclic graph (DAG). If we represent services as boxes and extensions
10754 as arrows, a typical system might provide something like this:
10756 @image{images/service-graph,,5in,Typical service extension graph.}
10758 @cindex system service
10759 At the bottom, we see the @dfn{system service}, which produces the
10760 directory containing everything to run and boot the system, as returned
10761 by the @command{guix system build} command. @xref{Service Reference},
10762 to learn about the other service types shown here.
10763 @xref{system-extension-graph, the @command{guix system extension-graph}
10764 command}, for information on how to generate this representation for a
10765 particular operating system definition.
10767 @cindex service types
10768 Technically, developers can define @dfn{service types} to express these
10769 relations. There can be any number of services of a given type on the
10770 system---for instance, a system running two instances of the GNU secure
10771 shell server (lsh) has two instances of @var{lsh-service-type}, with
10772 different parameters.
10774 The following section describes the programming interface for service
10775 types and services.
10777 @node Service Types and Services
10778 @subsubsection Service Types and Services
10780 A @dfn{service type} is a node in the DAG described above. Let us start
10781 with a simple example, the service type for the Guix build daemon
10782 (@pxref{Invoking guix-daemon}):
10785 (define guix-service-type
10789 (list (service-extension shepherd-root-service-type guix-shepherd-service)
10790 (service-extension account-service-type guix-accounts)
10791 (service-extension activation-service-type guix-activation)))))
10795 It defines two things:
10799 A name, whose sole purpose is to make inspection and debugging easier.
10802 A list of @dfn{service extensions}, where each extension designates the
10803 target service type and a procedure that, given the parameters of the
10804 service, returns a list of objects to extend the service of that type.
10806 Every service type has at least one service extension. The only
10807 exception is the @dfn{boot service type}, which is the ultimate service.
10810 In this example, @var{guix-service-type} extends three services:
10813 @item shepherd-root-service-type
10814 The @var{guix-shepherd-service} procedure defines how the Shepherd
10815 service is extended. Namely, it returns a @code{<shepherd-service>}
10816 object that defines how @command{guix-daemon} is started and stopped
10817 (@pxref{Shepherd Services}).
10819 @item account-service-type
10820 This extension for this service is computed by @var{guix-accounts},
10821 which returns a list of @code{user-group} and @code{user-account}
10822 objects representing the build user accounts (@pxref{Invoking
10825 @item activation-service-type
10826 Here @var{guix-activation} is a procedure that returns a gexp, which is
10827 a code snippet to run at ``activation time''---e.g., when the service is
10831 A service of this type is instantiated like this:
10834 (service guix-service-type
10835 (guix-configuration
10837 (use-substitutes? #f)))
10840 The second argument to the @code{service} form is a value representing
10841 the parameters of this specific service instance.
10842 @xref{guix-configuration-type, @code{guix-configuration}}, for
10843 information about the @code{guix-configuration} data type.
10845 @var{guix-service-type} is quite simple because it extends other
10846 services but is not extensible itself.
10848 @c @subsubsubsection Extensible Service Types
10850 The service type for an @emph{extensible} service looks like this:
10853 (define udev-service-type
10854 (service-type (name 'udev)
10856 (list (service-extension shepherd-root-service-type
10857 udev-shepherd-service)))
10859 (compose concatenate) ;concatenate the list of rules
10860 (extend (lambda (config rules)
10862 (($ <udev-configuration> udev initial-rules)
10863 (udev-configuration
10864 (udev udev) ;the udev package to use
10865 (rules (append initial-rules rules)))))))))
10868 This is the service type for the
10869 @uref{https://wiki.gentoo.org/wiki/Project:Eudev, eudev device
10870 management daemon}. Compared to the previous example, in addition to an
10871 extension of @var{shepherd-root-service-type}, we see two new fields:
10875 This is the procedure to @dfn{compose} the list of extensions to
10876 services of this type.
10878 Services can extend the udev service by passing it lists of rules; we
10879 compose those extensions simply by concatenating them.
10882 This procedure defines how the value of the service is @dfn{extended} with
10883 the composition of the extensions.
10885 Udev extensions are composed into a list of rules, but the udev service
10886 value is itself a @code{<udev-configuration>} record. So here, we
10887 extend that record by appending the list of rules it contains to the
10888 list of contributed rules.
10891 There can be only one instance of an extensible service type such as
10892 @var{udev-service-type}. If there were more, the
10893 @code{service-extension} specifications would be ambiguous.
10895 Still here? The next section provides a reference of the programming
10896 interface for services.
10898 @node Service Reference
10899 @subsubsection Service Reference
10901 We have seen an overview of service types (@pxref{Service Types and
10902 Services}). This section provides a reference on how to manipulate
10903 services and service types. This interface is provided by the
10904 @code{(gnu services)} module.
10906 @deffn {Scheme Procedure} service @var{type} @var{value}
10907 Return a new service of @var{type}, a @code{<service-type>} object (see
10908 below.) @var{value} can be any object; it represents the parameters of
10909 this particular service instance.
10912 @deffn {Scheme Procedure} service? @var{obj}
10913 Return true if @var{obj} is a service.
10916 @deffn {Scheme Procedure} service-kind @var{service}
10917 Return the type of @var{service}---i.e., a @code{<service-type>} object.
10920 @deffn {Scheme Procedure} service-parameters @var{service}
10921 Return the value associated with @var{service}. It represents its
10925 Here is an example of how a service is created and manipulated:
10929 (service nginx-service-type
10930 (nginx-configuration
10932 (log-directory log-directory)
10933 (run-directory run-directory)
10934 (file config-file))))
10939 (eq? (service-kind s) nginx-service-type)
10943 The @code{modify-services} form provides a handy way to change the
10944 parameters of some of the services of a list such as
10945 @var{%base-services} (@pxref{Base Services, @code{%base-services}}). It
10946 evalutes to a list of services. Of course, you could always use
10947 standard list combinators such as @code{map} and @code{fold} to do that
10948 (@pxref{SRFI-1, List Library,, guile, GNU Guile Reference Manual});
10949 @code{modify-services} simply provides a more concise form for this
10952 @deffn {Scheme Syntax} modify-services @var{services} @
10953 (@var{type} @var{variable} => @var{body}) @dots{}
10955 Modify the services listed in @var{services} according to the given
10956 clauses. Each clause has the form:
10959 (@var{type} @var{variable} => @var{body})
10962 where @var{type} is a service type---e.g.,
10963 @code{guix-service-type}---and @var{variable} is an identifier that is
10964 bound within the @var{body} to the service parameters---e.g., a
10965 @code{guix-configuration} instance---of the original service of that
10968 The @var{body} should evaluate to the new service parameters, which will
10969 be used to configure the new service. This new service will replace the
10970 original in the resulting list. Because a service's service parameters
10971 are created using @code{define-record-type*}, you can write a succint
10972 @var{body} that evaluates to the new service parameters by using the
10973 @code{inherit} feature that @code{define-record-type*} provides.
10975 @xref{Using the Configuration System}, for example usage.
10979 Next comes the programming interface for service types. This is
10980 something you want to know when writing new service definitions, but not
10981 necessarily when simply looking for ways to customize your
10982 @code{operating-system} declaration.
10984 @deftp {Data Type} service-type
10985 @cindex service type
10986 This is the representation of a @dfn{service type} (@pxref{Service Types
10991 This is a symbol, used only to simplify inspection and debugging.
10993 @item @code{extensions}
10994 A non-empty list of @code{<service-extension>} objects (see below).
10996 @item @code{compose} (default: @code{#f})
10997 If this is @code{#f}, then the service type denotes services that cannot
10998 be extended---i.e., services that do not receive ``values'' from other
11001 Otherwise, it must be a one-argument procedure. The procedure is called
11002 by @code{fold-services} and is passed a list of values collected from
11003 extensions. It must return a value that is a valid parameter value for
11004 the service instance.
11006 @item @code{extend} (default: @code{#f})
11007 If this is @code{#f}, services of this type cannot be extended.
11009 Otherwise, it must be a two-argument procedure: @code{fold-services}
11010 calls it, passing it the initial value of the service as the first argument
11011 and the result of applying @code{compose} to the extension values as the
11015 @xref{Service Types and Services}, for examples.
11018 @deffn {Scheme Procedure} service-extension @var{target-type} @
11020 Return a new extension for services of type @var{target-type}.
11021 @var{compute} must be a one-argument procedure: @code{fold-services}
11022 calls it, passing it the value associated with the service that provides
11023 the extension; it must return a valid value for the target service.
11026 @deffn {Scheme Procedure} service-extension? @var{obj}
11027 Return true if @var{obj} is a service extension.
11030 At the core of the service abstraction lies the @code{fold-services}
11031 procedure, which is responsible for ``compiling'' a list of services
11032 down to a single directory that contains everything needed to boot and
11033 run the system---the directory shown by the @command{guix system build}
11034 command (@pxref{Invoking guix system}). In essence, it propagates
11035 service extensions down the service graph, updating each node parameters
11036 on the way, until it reaches the root node.
11038 @deffn {Scheme Procedure} fold-services @var{services} @
11039 [#:target-type @var{system-service-type}]
11040 Fold @var{services} by propagating their extensions down to the root of
11041 type @var{target-type}; return the root service adjusted accordingly.
11044 Lastly, the @code{(gnu services)} module also defines several essential
11045 service types, some of which are listed below.
11047 @defvr {Scheme Variable} system-service-type
11048 This is the root of the service graph. It produces the system directory
11049 as returned by the @command{guix system build} command.
11052 @defvr {Scheme Variable} boot-service-type
11053 The type of the ``boot service'', which produces the @dfn{boot script}.
11054 The boot script is what the initial RAM disk runs when booting.
11057 @defvr {Scheme Variable} etc-service-type
11058 The type of the @file{/etc} service. This service can be extended by
11059 passing it name/file tuples such as:
11062 (list `("issue" ,(plain-file "issue" "Welcome!\n")))
11065 In this example, the effect would be to add an @file{/etc/issue} file
11066 pointing to the given file.
11069 @defvr {Scheme Variable} setuid-program-service-type
11070 Type for the ``setuid-program service''. This service collects lists of
11071 executable file names, passed as gexps, and adds them to the set of
11072 setuid-root programs on the system (@pxref{Setuid Programs}).
11075 @defvr {Scheme Variable} profile-service-type
11076 Type of the service that populates the @dfn{system profile}---i.e., the
11077 programs under @file{/run/current-system/profile}. Other services can
11078 extend it by passing it lists of packages to add to the system profile.
11082 @node Shepherd Services
11083 @subsubsection Shepherd Services
11086 @cindex init system
11087 The @code{(gnu services shepherd)} module provides a way to define
11088 services managed by the GNU@tie{}Shepherd, which is the GuixSD
11089 initialization system---the first process that is started when the
11090 system boots, also known as PID@tie{}1
11091 (@pxref{Introduction,,, shepherd, The GNU Shepherd Manual}).
11093 Services in the Shepherd can depend on each other. For instance, the
11094 SSH daemon may need to be started after the syslog daemon has been
11095 started, which in turn can only happen once all the file systems have
11096 been mounted. The simple operating system defined earlier (@pxref{Using
11097 the Configuration System}) results in a service graph like this:
11099 @image{images/shepherd-graph,,5in,Typical shepherd service graph.}
11101 You can actually generate such a graph for any operating system
11102 definition using the @command{guix system shepherd-graph} command
11103 (@pxref{system-shepherd-graph, @command{guix system shepherd-graph}}).
11105 The @var{%shepherd-root-service} is a service object representing
11106 PID@tie{}1, of type @var{shepherd-root-service-type}; it can be extended
11107 by passing it lists of @code{<shepherd-service>} objects.
11109 @deftp {Data Type} shepherd-service
11110 The data type representing a service managed by the Shepherd.
11113 @item @code{provision}
11114 This is a list of symbols denoting what the service provides.
11116 These are the names that may be passed to @command{herd start},
11117 @command{herd status}, and similar commands (@pxref{Invoking herd,,,
11118 shepherd, The GNU Shepherd Manual}). @xref{Slots of services, the
11119 @code{provides} slot,, shepherd, The GNU Shepherd Manual}, for details.
11121 @item @code{requirements} (default: @code{'()})
11122 List of symbols denoting the Shepherd services this one depends on.
11124 @item @code{respawn?} (default: @code{#t})
11125 Whether to restart the service when it stops, for instance when the
11126 underlying process dies.
11129 @itemx @code{stop} (default: @code{#~(const #f)})
11130 The @code{start} and @code{stop} fields refer to the Shepherd's
11131 facilities to start and stop processes (@pxref{Service De- and
11132 Constructors,,, shepherd, The GNU Shepherd Manual}). They are given as
11133 G-expressions that get expanded in the Shepherd configuration file
11134 (@pxref{G-Expressions}).
11136 @item @code{documentation}
11137 A documentation string, as shown when running:
11140 herd doc @var{service-name}
11143 where @var{service-name} is one of the symbols in @var{provision}
11144 (@pxref{Invoking herd,,, shepherd, The GNU Shepherd Manual}).
11146 @item @code{modules} (default: @var{%default-modules})
11147 This is the list of modules that must be in scope when @code{start} and
11148 @code{stop} are evaluated.
11153 @defvr {Scheme Variable} shepherd-root-service-type
11154 The service type for the Shepherd ``root service''---i.e., PID@tie{}1.
11156 This is the service type that extensions target when they want to create
11157 shepherd services (@pxref{Service Types and Services}, for an example).
11158 Each extension must pass a list of @code{<shepherd-service>}.
11161 @defvr {Scheme Variable} %shepherd-root-service
11162 This service represents PID@tie{}1.
11166 @node Installing Debugging Files
11167 @section Installing Debugging Files
11169 @cindex debugging files
11170 Program binaries, as produced by the GCC compilers for instance, are
11171 typically written in the ELF format, with a section containing
11172 @dfn{debugging information}. Debugging information is what allows the
11173 debugger, GDB, to map binary code to source code; it is required to
11174 debug a compiled program in good conditions.
11176 The problem with debugging information is that is takes up a fair amount
11177 of disk space. For example, debugging information for the GNU C Library
11178 weighs in at more than 60 MiB. Thus, as a user, keeping all the
11179 debugging info of all the installed programs is usually not an option.
11180 Yet, space savings should not come at the cost of an impediment to
11181 debugging---especially in the GNU system, which should make it easier
11182 for users to exert their computing freedom (@pxref{GNU Distribution}).
11184 Thankfully, the GNU Binary Utilities (Binutils) and GDB provide a
11185 mechanism that allows users to get the best of both worlds: debugging
11186 information can be stripped from the binaries and stored in separate
11187 files. GDB is then able to load debugging information from those files,
11188 when they are available (@pxref{Separate Debug Files,,, gdb, Debugging
11191 The GNU distribution takes advantage of this by storing debugging
11192 information in the @code{lib/debug} sub-directory of a separate package
11193 output unimaginatively called @code{debug} (@pxref{Packages with
11194 Multiple Outputs}). Users can choose to install the @code{debug} output
11195 of a package when they need it. For instance, the following command
11196 installs the debugging information for the GNU C Library and for GNU
11200 guix package -i glibc:debug guile:debug
11203 GDB must then be told to look for debug files in the user's profile, by
11204 setting the @code{debug-file-directory} variable (consider setting it
11205 from the @file{~/.gdbinit} file, @pxref{Startup,,, gdb, Debugging with
11209 (gdb) set debug-file-directory ~/.guix-profile/lib/debug
11212 From there on, GDB will pick up debugging information from the
11213 @code{.debug} files under @file{~/.guix-profile/lib/debug}.
11215 In addition, you will most likely want GDB to be able to show the source
11216 code being debugged. To do that, you will have to unpack the source
11217 code of the package of interest (obtained with @code{guix build
11218 --source}, @pxref{Invoking guix build}), and to point GDB to that source
11219 directory using the @code{directory} command (@pxref{Source Path,
11220 @code{directory},, gdb, Debugging with GDB}).
11222 @c XXX: keep me up-to-date
11223 The @code{debug} output mechanism in Guix is implemented by the
11224 @code{gnu-build-system} (@pxref{Build Systems}). Currently, it is
11225 opt-in---debugging information is available only for the packages
11226 with definitions explicitly declaring a @code{debug} output. This may be
11227 changed to opt-out in the future if our build farm servers can handle
11228 the load. To check whether a package has a @code{debug} output, use
11229 @command{guix package --list-available} (@pxref{Invoking guix package}).
11232 @node Security Updates
11233 @section Security Updates
11235 @cindex security updates
11236 @cindex security vulnerabilities
11237 Occasionally, important security vulnerabilities are discovered in software
11238 packages and must be patched. Guix developers try hard to keep track of
11239 known vulnerabilities and to apply fixes as soon as possible in the
11240 @code{master} branch of Guix (we do not yet provide a ``stable'' branch
11241 containing only security updates.) The @command{guix lint} tool helps
11242 developers find out about vulnerable versions of software packages in the
11247 gnu/packages/base.scm:652:2: glibc-2.21: probably vulnerable to CVE-2015-1781, CVE-2015-7547
11248 gnu/packages/gcc.scm:334:2: gcc-4.9.3: probably vulnerable to CVE-2015-5276
11249 gnu/packages/image.scm:312:2: openjpeg-2.1.0: probably vulnerable to CVE-2016-1923, CVE-2016-1924
11253 @xref{Invoking guix lint}, for more information.
11256 As of version @value{VERSION}, the feature described below is considered
11260 Guix follows a functional
11261 package management discipline (@pxref{Introduction}), which implies
11262 that, when a package is changed, @emph{every package that depends on it}
11263 must be rebuilt. This can significantly slow down the deployment of
11264 fixes in core packages such as libc or Bash, since basically the whole
11265 distribution would need to be rebuilt. Using pre-built binaries helps
11266 (@pxref{Substitutes}), but deployment may still take more time than
11270 To address this, Guix implements @dfn{grafts}, a mechanism that allows
11271 for fast deployment of critical updates without the costs associated
11272 with a whole-distribution rebuild. The idea is to rebuild only the
11273 package that needs to be patched, and then to ``graft'' it onto packages
11274 explicitly installed by the user and that were previously referring to
11275 the original package. The cost of grafting is typically very low, and
11276 order of magnitudes lower than a full rebuild of the dependency chain.
11278 @cindex replacements of packages, for grafts
11279 For instance, suppose a security update needs to be applied to Bash.
11280 Guix developers will provide a package definition for the ``fixed''
11281 Bash, say @var{bash-fixed}, in the usual way (@pxref{Defining
11282 Packages}). Then, the original package definition is augmented with a
11283 @code{replacement} field pointing to the package containing the bug fix:
11290 (replacement bash-fixed)))
11293 From there on, any package depending directly or indirectly on Bash---as
11294 reported by @command{guix gc --requisites} (@pxref{Invoking guix
11295 gc})---that is installed is automatically ``rewritten'' to refer to
11296 @var{bash-fixed} instead of @var{bash}. This grafting process takes
11297 time proportional to the size of the package, usually less than a
11298 minute for an ``average'' package on a recent machine. Grafting is
11299 recursive: when an indirect dependency requires grafting, then grafting
11300 ``propagates'' up to the package that the user is installing.
11302 Currently, the graft and the package it replaces (@var{bash-fixed} and
11303 @var{bash} in the example above) must have the exact same @code{name}
11304 and @code{version} fields. This restriction mostly comes from the fact
11305 that grafting works by patching files, including binary files, directly.
11306 Other restrictions may apply: for instance, when adding a graft to a
11307 package providing a shared library, the original shared library and its
11308 replacement must have the same @code{SONAME} and be binary-compatible.
11310 The @option{--no-grafts} command-line option allows you to forcefully
11311 avoid grafting (@pxref{Common Build Options, @option{--no-grafts}}).
11315 guix build bash --no-grafts
11319 returns the store file name of the original Bash, whereas:
11326 returns the store file name of the ``fixed'', replacement Bash. This
11327 allows you to distinguish between the two variants of Bash.
11329 To verify which Bash your whole profile refers to, you can run
11330 (@pxref{Invoking guix gc}):
11333 guix gc -R `readlink -f ~/.guix-profile` | grep bash
11337 @dots{} and compare the store file names that you get with those above.
11338 Likewise for a complete GuixSD system generation:
11341 guix gc -R `guix system build my-config.scm` | grep bash
11344 Lastly, to check which Bash running processes are using, you can use the
11345 @command{lsof} command:
11348 lsof | grep /gnu/store/.*bash
11352 @node Package Modules
11353 @section Package Modules
11355 From a programming viewpoint, the package definitions of the
11356 GNU distribution are provided by Guile modules in the @code{(gnu packages
11357 @dots{})} name space@footnote{Note that packages under the @code{(gnu
11358 packages @dots{})} module name space are not necessarily ``GNU
11359 packages''. This module naming scheme follows the usual Guile module
11360 naming convention: @code{gnu} means that these modules are distributed
11361 as part of the GNU system, and @code{packages} identifies modules that
11362 define packages.} (@pxref{Modules, Guile modules,, guile, GNU Guile
11363 Reference Manual}). For instance, the @code{(gnu packages emacs)}
11364 module exports a variable named @code{emacs}, which is bound to a
11365 @code{<package>} object (@pxref{Defining Packages}).
11367 The @code{(gnu packages @dots{})} module name space is
11368 automatically scanned for packages by the command-line tools. For
11369 instance, when running @code{guix package -i emacs}, all the @code{(gnu
11370 packages @dots{})} modules are scanned until one that exports a package
11371 object whose name is @code{emacs} is found. This package search
11372 facility is implemented in the @code{(gnu packages)} module.
11374 @cindex customization, of packages
11375 @cindex package module search path
11376 Users can store package definitions in modules with different
11377 names---e.g., @code{(my-packages emacs)}@footnote{Note that the file
11378 name and module name must match. For instance, the @code{(my-packages
11379 emacs)} module must be stored in a @file{my-packages/emacs.scm} file
11380 relative to the load path specified with @option{--load-path} or
11381 @code{GUIX_PACKAGE_PATH}. @xref{Modules and the File System,,,
11382 guile, GNU Guile Reference Manual}, for details.}. These package definitions
11383 will not be visible by default. Users can invoke commands such as
11384 @command{guix package} and @command{guix build} with the
11385 @code{-e} option so that they know where to find the package. Better
11386 yet, they can use the
11387 @code{-L} option of these commands to make those modules visible
11388 (@pxref{Invoking guix build, @code{--load-path}}), or define the
11389 @code{GUIX_PACKAGE_PATH} environment variable. This environment
11390 variable makes it easy to extend or customize the distribution and is
11391 honored by all the user interfaces.
11393 @defvr {Environment Variable} GUIX_PACKAGE_PATH
11394 This is a colon-separated list of directories to search for additional
11395 package modules. Directories listed in this variable take precedence
11396 over the own modules of the distribution.
11399 The distribution is fully @dfn{bootstrapped} and @dfn{self-contained}:
11400 each package is built based solely on other packages in the
11401 distribution. The root of this dependency graph is a small set of
11402 @dfn{bootstrap binaries}, provided by the @code{(gnu packages
11403 bootstrap)} module. For more information on bootstrapping,
11404 @pxref{Bootstrapping}.
11406 @node Packaging Guidelines
11407 @section Packaging Guidelines
11409 The GNU distribution is nascent and may well lack some of your favorite
11410 packages. This section describes how you can help make the distribution
11411 grow. @xref{Contributing}, for additional information on how you can
11414 Free software packages are usually distributed in the form of
11415 @dfn{source code tarballs}---typically @file{tar.gz} files that contain
11416 all the source files. Adding a package to the distribution means
11417 essentially two things: adding a @dfn{recipe} that describes how to
11418 build the package, including a list of other packages required to build
11419 it, and adding @dfn{package metadata} along with that recipe, such as a
11420 description and licensing information.
11422 In Guix all this information is embodied in @dfn{package definitions}.
11423 Package definitions provide a high-level view of the package. They are
11424 written using the syntax of the Scheme programming language; in fact,
11425 for each package we define a variable bound to the package definition,
11426 and export that variable from a module (@pxref{Package Modules}).
11427 However, in-depth Scheme knowledge is @emph{not} a prerequisite for
11428 creating packages. For more information on package definitions,
11429 @pxref{Defining Packages}.
11431 Once a package definition is in place, stored in a file in the Guix
11432 source tree, it can be tested using the @command{guix build} command
11433 (@pxref{Invoking guix build}). For example, assuming the new package is
11434 called @code{gnew}, you may run this command from the Guix build tree
11435 (@pxref{Running Guix Before It Is Installed}):
11438 ./pre-inst-env guix build gnew --keep-failed
11441 Using @code{--keep-failed} makes it easier to debug build failures since
11442 it provides access to the failed build tree. Another useful
11443 command-line option when debugging is @code{--log-file}, to access the
11446 If the package is unknown to the @command{guix} command, it may be that
11447 the source file contains a syntax error, or lacks a @code{define-public}
11448 clause to export the package variable. To figure it out, you may load
11449 the module from Guile to get more information about the actual error:
11452 ./pre-inst-env guile -c '(use-modules (gnu packages gnew))'
11455 Once your package builds correctly, please send us a patch
11456 (@pxref{Contributing}). Well, if you need help, we will be happy to
11457 help you too. Once the patch is committed in the Guix repository, the
11458 new package automatically gets built on the supported platforms by
11459 @url{http://hydra.gnu.org/jobset/gnu/master, our continuous integration
11462 @cindex substituter
11463 Users can obtain the new package definition simply by running
11464 @command{guix pull} (@pxref{Invoking guix pull}). When
11465 @code{hydra.gnu.org} is done building the package, installing the
11466 package automatically downloads binaries from there
11467 (@pxref{Substitutes}). The only place where human intervention is
11468 needed is to review and apply the patch.
11472 * Software Freedom:: What may go into the distribution.
11473 * Package Naming:: What's in a name?
11474 * Version Numbers:: When the name is not enough.
11475 * Synopses and Descriptions:: Helping users find the right package.
11476 * Python Modules:: Taming the snake.
11477 * Perl Modules:: Little pearls.
11478 * Java Packages:: Coffee break.
11479 * Fonts:: Fond of fonts.
11482 @node Software Freedom
11483 @subsection Software Freedom
11485 @c Adapted from http://www.gnu.org/philosophy/philosophy.html.
11487 The GNU operating system has been developed so that users can have
11488 freedom in their computing. GNU is @dfn{free software}, meaning that
11489 users have the @url{http://www.gnu.org/philosophy/free-sw.html,four
11490 essential freedoms}: to run the program, to study and change the program
11491 in source code form, to redistribute exact copies, and to distribute
11492 modified versions. Packages found in the GNU distribution provide only
11493 software that conveys these four freedoms.
11495 In addition, the GNU distribution follow the
11496 @url{http://www.gnu.org/distros/free-system-distribution-guidelines.html,free
11497 software distribution guidelines}. Among other things, these guidelines
11498 reject non-free firmware, recommendations of non-free software, and
11499 discuss ways to deal with trademarks and patents.
11501 Some otherwise free upstream package sources contain a small and optional
11502 subset that violates the above guidelines, for instance because this subset
11503 is itself non-free code. When that happens, the offending items are removed
11504 with appropriate patches or code snippets in the @code{origin} form of the
11505 package (@pxref{Defining Packages}). This way, @code{guix
11506 build --source} returns the ``freed'' source rather than the unmodified
11510 @node Package Naming
11511 @subsection Package Naming
11513 A package has actually two names associated with it:
11514 First, there is the name of the @emph{Scheme variable}, the one following
11515 @code{define-public}. By this name, the package can be made known in the
11516 Scheme code, for instance as input to another package. Second, there is
11517 the string in the @code{name} field of a package definition. This name
11518 is used by package management commands such as
11519 @command{guix package} and @command{guix build}.
11521 Both are usually the same and correspond to the lowercase conversion of
11522 the project name chosen upstream, with underscores replaced with
11523 hyphens. For instance, GNUnet is available as @code{gnunet}, and
11524 SDL_net as @code{sdl-net}.
11526 We do not add @code{lib} prefixes for library packages, unless these are
11527 already part of the official project name. But @pxref{Python
11528 Modules} and @ref{Perl Modules} for special rules concerning modules for
11529 the Python and Perl languages.
11531 Font package names are handled differently, @pxref{Fonts}.
11534 @node Version Numbers
11535 @subsection Version Numbers
11537 We usually package only the latest version of a given free software
11538 project. But sometimes, for instance for incompatible library versions,
11539 two (or more) versions of the same package are needed. These require
11540 different Scheme variable names. We use the name as defined
11541 in @ref{Package Naming}
11542 for the most recent version; previous versions use the same name, suffixed
11543 by @code{-} and the smallest prefix of the version number that may
11544 distinguish the two versions.
11546 The name inside the package definition is the same for all versions of a
11547 package and does not contain any version number.
11549 For instance, the versions 2.24.20 and 3.9.12 of GTK+ may be packaged as follows:
11552 (define-public gtk+
11557 (define-public gtk+-2
11560 (version "2.24.20")
11563 If we also wanted GTK+ 3.8.2, this would be packaged as
11565 (define-public gtk+-3.8
11572 @c See <https://lists.gnu.org/archive/html/guix-devel/2016-01/msg00425.html>,
11573 @c for a discussion of what follows.
11574 @cindex version number, for VCS snapshots
11575 Occasionally, we package snapshots of upstream's version control system
11576 (VCS) instead of formal releases. This should remain exceptional,
11577 because it is up to upstream developers to clarify what the stable
11578 release is. Yet, it is sometimes necessary. So, what should we put in
11579 the @code{version} field?
11581 Clearly, we need to make the commit identifier of the VCS snapshot
11582 visible in the version string, but we also need to make sure that the
11583 version string is monotonically increasing so that @command{guix package
11584 --upgrade} can determine which version is newer. Since commit
11585 identifiers, notably with Git, are not monotonically increasing, we add
11586 a revision number that we increase each time we upgrade to a newer
11587 snapshot. The resulting version string looks like this:
11592 | | `-- upstream commit ID
11594 | `--- Guix package revision
11596 latest upstream version
11599 It is a good idea to strip commit identifiers in the @code{version}
11600 field to, say, 7 digits. It avoids an aesthetic annoyance (assuming
11601 aesthetics have a role to play here) as well as problems related to OS
11602 limits such as the maximum shebang length (127 bytes for the Linux
11603 kernel.) It is best to use the full commit identifiers in
11604 @code{origin}s, though, to avoid ambiguities. A typical package
11605 definition may look like this:
11609 (let ((commit "c3f29bc928d5900971f65965feaae59e1272a3f7")
11610 (revision "1")) ;Guix package revision
11612 (version (string-append "0.9-" revision "."
11613 (string-take commit 7)))
11616 (uri (git-reference
11617 (url "git://example.org/my-package.git")
11619 (sha256 (base32 "1mbikn@dots{}"))
11620 (file-name (string-append "my-package-" version
11626 @node Synopses and Descriptions
11627 @subsection Synopses and Descriptions
11629 As we have seen before, each package in GNU@tie{}Guix includes a
11630 synopsis and a description (@pxref{Defining Packages}). Synopses and
11631 descriptions are important: They are what @command{guix package
11632 --search} searches, and a crucial piece of information to help users
11633 determine whether a given package suits their needs. Consequently,
11634 packagers should pay attention to what goes into them.
11636 Synopses must start with a capital letter and must not end with a
11637 period. They must not start with ``a'' or ``the'', which usually does
11638 not bring anything; for instance, prefer ``File-frobbing tool'' over ``A
11639 tool that frobs files''. The synopsis should say what the package
11640 is---e.g., ``Core GNU utilities (file, text, shell)''---or what it is
11641 used for---e.g., the synopsis for GNU@tie{}grep is ``Print lines
11642 matching a pattern''.
11644 Keep in mind that the synopsis must be meaningful for a very wide
11645 audience. For example, ``Manipulate alignments in the SAM format''
11646 might make sense for a seasoned bioinformatics researcher, but might be
11647 fairly unhelpful or even misleading to a non-specialized audience. It
11648 is a good idea to come up with a synopsis that gives an idea of the
11649 application domain of the package. In this example, this might give
11650 something like ``Manipulate nucleotide sequence alignments'', which
11651 hopefully gives the user a better idea of whether this is what they are
11654 Descriptions should take between five and ten lines. Use full
11655 sentences, and avoid using acronyms without first introducing them.
11656 Please avoid marketing phrases such as ``world-leading'',
11657 ``industrial-strength'', and ``next-generation'', and avoid superlatives
11658 like ``the most advanced''---they are not helpful to users looking for a
11659 package and may even sound suspicious. Instead, try to be factual,
11660 mentioning use cases and features.
11662 @cindex Texinfo markup, in package descriptions
11663 Descriptions can include Texinfo markup, which is useful to introduce
11664 ornaments such as @code{@@code} or @code{@@dfn}, bullet lists, or
11665 hyperlinks (@pxref{Overview,,, texinfo, GNU Texinfo}). However you
11666 should be careful when using some characters for example @samp{@@} and
11667 curly braces which are the basic special characters in Texinfo
11668 (@pxref{Special Characters,,, texinfo, GNU Texinfo}). User interfaces
11669 such as @command{guix package --show} take care of rendering it
11672 Synopses and descriptions are translated by volunteers
11673 @uref{http://translationproject.org/domain/guix-packages.html, at the
11674 Translation Project} so that as many users as possible can read them in
11675 their native language. User interfaces search them and display them in
11676 the language specified by the current locale.
11678 Translation is a lot of work so, as a packager, please pay even more
11679 attention to your synopses and descriptions as every change may entail
11680 additional work for translators. In order to help them, it is possible
11681 to make recommendations or instructions visible to them by inserting
11682 special comments like this (@pxref{xgettext Invocation,,, gettext, GNU
11686 ;; TRANSLATORS: "X11 resize-and-rotate" should not be translated.
11687 (description "ARandR is designed to provide a simple visual front end
11688 for the X11 resize-and-rotate (RandR) extension. @dots{}")
11692 @node Python Modules
11693 @subsection Python Modules
11695 We currently package Python 2 and Python 3, under the Scheme variable names
11696 @code{python-2} and @code{python} as explained in @ref{Version Numbers}.
11697 To avoid confusion and naming clashes with other programming languages, it
11698 seems desirable that the name of a package for a Python module contains
11699 the word @code{python}.
11701 Some modules are compatible with only one version of Python, others with both.
11702 If the package Foo compiles only with Python 3, we name it
11703 @code{python-foo}; if it compiles only with Python 2, we name it
11704 @code{python2-foo}. If it is compatible with both versions, we create two
11705 packages with the corresponding names.
11707 If a project already contains the word @code{python}, we drop this;
11708 for instance, the module python-dateutil is packaged under the names
11709 @code{python-dateutil} and @code{python2-dateutil}. If the project name
11710 starts with @code{py} (e.g. @code{pytz}), we keep it and prefix it as
11715 @subsection Perl Modules
11717 Perl programs standing for themselves are named as any other package,
11718 using the lowercase upstream name.
11719 For Perl packages containing a single class, we use the lowercase class name,
11720 replace all occurrences of @code{::} by dashes and prepend the prefix
11722 So the class @code{XML::Parser} becomes @code{perl-xml-parser}.
11723 Modules containing several classes keep their lowercase upstream name and
11724 are also prepended by @code{perl-}. Such modules tend to have the word
11725 @code{perl} somewhere in their name, which gets dropped in favor of the
11726 prefix. For instance, @code{libwww-perl} becomes @code{perl-libwww}.
11729 @node Java Packages
11730 @subsection Java Packages
11732 Java programs standing for themselves are named as any other package,
11733 using the lowercase upstream name.
11735 To avoid confusion and naming clashes with other programming languages,
11736 it is desirable that the name of a package for a Java package is
11737 prefixed with @code{java-}. If a project already contains the word
11738 @code{java}, we drop this; for instance, the package @code{ngsjava} is
11739 packaged under the name @code{java-ngs}.
11741 For Java packages containing a single class or a small class hierarchy,
11742 we use the lowercase class name, replace all occurrences of @code{.} by
11743 dashes and prepend the prefix @code{java-}. So the class
11744 @code{apache.commons.cli} becomes package
11745 @code{java-apache-commons-cli}.
11751 For fonts that are in general not installed by a user for typesetting
11752 purposes, or that are distributed as part of a larger software package,
11753 we rely on the general packaging rules for software; for instance, this
11754 applies to the fonts delivered as part of the X.Org system or fonts that
11755 are part of TeX Live.
11757 To make it easier for a user to search for fonts, names for other packages
11758 containing only fonts are constructed as follows, independently of the
11759 upstream package name.
11761 The name of a package containing only one font family starts with
11762 @code{font-}; it is followed by the foundry name and a dash @code{-}
11763 if the foundry is known, and the font family name, in which spaces are
11764 replaced by dashes (and as usual, all upper case letters are transformed
11766 For example, the Gentium font family by SIL is packaged under the name
11767 @code{font-sil-gentium}.
11769 For a package containing several font families, the name of the collection
11770 is used in the place of the font family name.
11771 For instance, the Liberation fonts consist of three families,
11772 Liberation Sans, Liberation Serif and Liberation Mono.
11773 These could be packaged separately under the names
11774 @code{font-liberation-sans} and so on; but as they are distributed together
11775 under a common name, we prefer to package them together as
11776 @code{font-liberation}.
11778 In the case where several formats of the same font family or font collection
11779 are packaged separately, a short form of the format, prepended by a dash,
11780 is added to the package name. We use @code{-ttf} for TrueType fonts,
11781 @code{-otf} for OpenType fonts and @code{-type1} for PostScript Type 1
11786 @node Bootstrapping
11787 @section Bootstrapping
11789 @c Adapted from the ELS 2013 paper.
11791 @cindex bootstrapping
11793 Bootstrapping in our context refers to how the distribution gets built
11794 ``from nothing''. Remember that the build environment of a derivation
11795 contains nothing but its declared inputs (@pxref{Introduction}). So
11796 there's an obvious chicken-and-egg problem: how does the first package
11797 get built? How does the first compiler get compiled? Note that this is
11798 a question of interest only to the curious hacker, not to the regular
11799 user, so you can shamelessly skip this section if you consider yourself
11800 a ``regular user''.
11802 @cindex bootstrap binaries
11803 The GNU system is primarily made of C code, with libc at its core. The
11804 GNU build system itself assumes the availability of a Bourne shell and
11805 command-line tools provided by GNU Coreutils, Awk, Findutils, `sed', and
11806 `grep'. Furthermore, build programs---programs that run
11807 @code{./configure}, @code{make}, etc.---are written in Guile Scheme
11808 (@pxref{Derivations}). Consequently, to be able to build anything at
11809 all, from scratch, Guix relies on pre-built binaries of Guile, GCC,
11810 Binutils, libc, and the other packages mentioned above---the
11811 @dfn{bootstrap binaries}.
11813 These bootstrap binaries are ``taken for granted'', though we can also
11814 re-create them if needed (more on that later).
11816 @unnumberedsubsec Preparing to Use the Bootstrap Binaries
11818 @c As of Emacs 24.3, Info-mode displays the image, but since it's a
11819 @c large image, it's hard to scroll. Oh well.
11820 @image{images/bootstrap-graph,6in,,Dependency graph of the early bootstrap derivations}
11822 The figure above shows the very beginning of the dependency graph of the
11823 distribution, corresponding to the package definitions of the @code{(gnu
11824 packages bootstrap)} module. A similar figure can be generated with
11825 @command{guix graph} (@pxref{Invoking guix graph}), along the lines of:
11828 guix graph -t derivation \
11829 -e '(@@@@ (gnu packages bootstrap) %bootstrap-gcc)' \
11833 At this level of detail, things are
11834 slightly complex. First, Guile itself consists of an ELF executable,
11835 along with many source and compiled Scheme files that are dynamically
11836 loaded when it runs. This gets stored in the @file{guile-2.0.7.tar.xz}
11837 tarball shown in this graph. This tarball is part of Guix's ``source''
11838 distribution, and gets inserted into the store with @code{add-to-store}
11839 (@pxref{The Store}).
11841 But how do we write a derivation that unpacks this tarball and adds it
11842 to the store? To solve this problem, the @code{guile-bootstrap-2.0.drv}
11843 derivation---the first one that gets built---uses @code{bash} as its
11844 builder, which runs @code{build-bootstrap-guile.sh}, which in turn calls
11845 @code{tar} to unpack the tarball. Thus, @file{bash}, @file{tar},
11846 @file{xz}, and @file{mkdir} are statically-linked binaries, also part of
11847 the Guix source distribution, whose sole purpose is to allow the Guile
11848 tarball to be unpacked.
11850 Once @code{guile-bootstrap-2.0.drv} is built, we have a functioning
11851 Guile that can be used to run subsequent build programs. Its first task
11852 is to download tarballs containing the other pre-built binaries---this
11853 is what the @code{.tar.xz.drv} derivations do. Guix modules such as
11854 @code{ftp-client.scm} are used for this purpose. The
11855 @code{module-import.drv} derivations import those modules in a directory
11856 in the store, using the original layout. The
11857 @code{module-import-compiled.drv} derivations compile those modules, and
11858 write them in an output directory with the right layout. This
11859 corresponds to the @code{#:modules} argument of
11860 @code{build-expression->derivation} (@pxref{Derivations}).
11862 Finally, the various tarballs are unpacked by the
11863 derivations @code{gcc-bootstrap-0.drv}, @code{glibc-bootstrap-0.drv},
11864 etc., at which point we have a working C tool chain.
11867 @unnumberedsubsec Building the Build Tools
11869 Bootstrapping is complete when we have a full tool chain that does not
11870 depend on the pre-built bootstrap tools discussed above. This
11871 no-dependency requirement is verified by checking whether the files of
11872 the final tool chain contain references to the @file{/gnu/store}
11873 directories of the bootstrap inputs. The process that leads to this
11874 ``final'' tool chain is described by the package definitions found in
11875 the @code{(gnu packages commencement)} module.
11877 The @command{guix graph} command allows us to ``zoom out'' compared to
11878 the graph above, by looking at the level of package objects instead of
11879 individual derivations---remember that a package may translate to
11880 several derivations, typically one derivation to download its source,
11881 one to build the Guile modules it needs, and one to actually build the
11882 package from source. The command:
11885 guix graph -t bag \
11886 -e '(@@@@ (gnu packages commencement)
11887 glibc-final-with-bootstrap-bash)' | dot -Tps > t.ps
11891 produces the dependency graph leading to the ``final'' C
11892 library@footnote{You may notice the @code{glibc-intermediate} label,
11893 suggesting that it is not @emph{quite} final, but as a good
11894 approximation, we will consider it final.}, depicted below.
11896 @image{images/bootstrap-packages,6in,,Dependency graph of the early packages}
11898 @c See <http://lists.gnu.org/archive/html/gnu-system-discuss/2012-10/msg00000.html>.
11899 The first tool that gets built with the bootstrap binaries is
11900 GNU@tie{}Make---noted @code{make-boot0} above---which is a prerequisite
11901 for all the following packages. From there Findutils and Diffutils get
11904 Then come the first-stage Binutils and GCC, built as pseudo cross
11905 tools---i.e., with @code{--target} equal to @code{--host}. They are
11906 used to build libc. Thanks to this cross-build trick, this libc is
11907 guaranteed not to hold any reference to the initial tool chain.
11909 From there the final Binutils and GCC (not shown above) are built.
11911 from the final Binutils, and links programs against the just-built libc.
11912 This tool chain is used to build the other packages used by Guix and by
11913 the GNU Build System: Guile, Bash, Coreutils, etc.
11915 And voilà! At this point we have the complete set of build tools that
11916 the GNU Build System expects. These are in the @code{%final-inputs}
11917 variable of the @code{(gnu packages commencement)} module, and are
11918 implicitly used by any package that uses @code{gnu-build-system}
11919 (@pxref{Build Systems, @code{gnu-build-system}}).
11922 @unnumberedsubsec Building the Bootstrap Binaries
11924 Because the final tool chain does not depend on the bootstrap binaries,
11925 those rarely need to be updated. Nevertheless, it is useful to have an
11926 automated way to produce them, should an update occur, and this is what
11927 the @code{(gnu packages make-bootstrap)} module provides.
11929 The following command builds the tarballs containing the bootstrap
11930 binaries (Guile, Binutils, GCC, libc, and a tarball containing a mixture
11931 of Coreutils and other basic command-line tools):
11934 guix build bootstrap-tarballs
11937 The generated tarballs are those that should be referred to in the
11938 @code{(gnu packages bootstrap)} module mentioned at the beginning of
11941 Still here? Then perhaps by now you've started to wonder: when do we
11942 reach a fixed point? That is an interesting question! The answer is
11943 unknown, but if you would like to investigate further (and have
11944 significant computational and storage resources to do so), then let us
11948 @section Porting to a New Platform
11950 As discussed above, the GNU distribution is self-contained, and
11951 self-containment is achieved by relying on pre-built ``bootstrap
11952 binaries'' (@pxref{Bootstrapping}). These binaries are specific to an
11953 operating system kernel, CPU architecture, and application binary
11954 interface (ABI). Thus, to port the distribution to a platform that is
11955 not yet supported, one must build those bootstrap binaries, and update
11956 the @code{(gnu packages bootstrap)} module to use them on that platform.
11958 Fortunately, Guix can @emph{cross compile} those bootstrap binaries.
11959 When everything goes well, and assuming the GNU tool chain supports the
11960 target platform, this can be as simple as running a command like this
11964 guix build --target=armv5tel-linux-gnueabi bootstrap-tarballs
11967 For this to work, the @code{glibc-dynamic-linker} procedure in
11968 @code{(gnu packages bootstrap)} must be augmented to return the right
11969 file name for libc's dynamic linker on that platform; likewise,
11970 @code{system->linux-architecture} in @code{(gnu packages linux)} must be
11971 taught about the new platform.
11973 Once these are built, the @code{(gnu packages bootstrap)} module needs
11974 to be updated to refer to these binaries on the target platform. That
11975 is, the hashes and URLs of the bootstrap tarballs for the new platform
11976 must be added alongside those of the currently supported platforms. The
11977 bootstrap Guile tarball is treated specially: it is expected to be
11978 available locally, and @file{gnu/local.mk} has rules do download it for
11979 the supported architectures; a rule for the new platform must be added
11982 In practice, there may be some complications. First, it may be that the
11983 extended GNU triplet that specifies an ABI (like the @code{eabi} suffix
11984 above) is not recognized by all the GNU tools. Typically, glibc
11985 recognizes some of these, whereas GCC uses an extra @code{--with-abi}
11986 configure flag (see @code{gcc.scm} for examples of how to handle this).
11987 Second, some of the required packages could fail to build for that
11988 platform. Lastly, the generated binaries could be broken for some
11991 @c *********************************************************************
11992 @include contributing.texi
11994 @c *********************************************************************
11995 @node Acknowledgments
11996 @chapter Acknowledgments
11998 Guix is based on the @uref{http://nixos.org/nix/, Nix package manager},
11999 which was designed and
12000 implemented by Eelco Dolstra, with contributions from other people (see
12001 the @file{nix/AUTHORS} file in Guix.) Nix pioneered functional package
12002 management, and promoted unprecedented features, such as transactional
12003 package upgrades and rollbacks, per-user profiles, and referentially
12004 transparent build processes. Without this work, Guix would not exist.
12006 The Nix-based software distributions, Nixpkgs and NixOS, have also been
12007 an inspiration for Guix.
12009 GNU@tie{}Guix itself is a collective work with contributions from a
12010 number of people. See the @file{AUTHORS} file in Guix for more
12011 information on these fine people. The @file{THANKS} file lists people
12012 who have helped by reporting bugs, taking care of the infrastructure,
12013 providing artwork and themes, making suggestions, and more---thank you!
12016 @c *********************************************************************
12017 @node GNU Free Documentation License
12018 @appendix GNU Free Documentation License
12020 @include fdl-1.3.texi
12022 @c *********************************************************************
12023 @node Concept Index
12024 @unnumbered Concept Index
12027 @node Programming Index
12028 @unnumbered Programming Index
12029 @syncodeindex tp fn
12030 @syncodeindex vr fn
12035 @c Local Variables:
12036 @c ispell-local-dictionary: "american";