6 @documentencoding UTF-8
7 @settitle GNU Guix Reference Manual
13 Copyright @copyright{} 2012, 2013, 2014, 2015, 2016 Ludovic Courtès@*
14 Copyright @copyright{} 2013, 2014, 2016 Andreas Enge@*
15 Copyright @copyright{} 2013 Nikita Karetnikov@*
16 Copyright @copyright{} 2014, 2015, 2016 Alex Kost@*
17 Copyright @copyright{} 2015, 2016 Mathieu Lirzin@*
18 Copyright @copyright{} 2014 Pierre-Antoine Rault@*
19 Copyright @copyright{} 2015 Taylan Ulrich Bayırlı/Kammer@*
20 Copyright @copyright{} 2015, 2016 Leo Famulari@*
21 Copyright @copyright{} 2015, 2016 Ricardo Wurmus@*
22 Copyright @copyright{} 2016 Ben Woodcroft@*
23 Copyright @copyright{} 2016 Chris Marusich@*
24 Copyright @copyright{} 2016 Efraim Flashner@*
25 Copyright @copyright{} 2016 ng0
27 Permission is granted to copy, distribute and/or modify this document
28 under the terms of the GNU Free Documentation License, Version 1.3 or
29 any later version published by the Free Software Foundation; with no
30 Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A
31 copy of the license is included in the section entitled ``GNU Free
32 Documentation License''.
35 @dircategory System administration
37 * Guix: (guix). Manage installed software and system configuration.
38 * guix package: (guix)Invoking guix package. Installing, removing, and upgrading packages.
39 * guix build: (guix)Invoking guix build. Building packages.
40 * guix gc: (guix)Invoking guix gc. Reclaiming unused disk space.
41 * guix pull: (guix)Invoking guix pull. Update the list of available packages.
42 * guix system: (guix)Invoking guix system. Manage the operating system configuration.
45 @dircategory Software development
47 * guix environment: (guix)Invoking guix environment. Building development environments with Guix.
52 * Guix user interface: (guix)Emacs Interface. Package management from the comfort of Emacs.
57 @title GNU Guix Reference Manual
58 @subtitle Using the GNU Guix Functional Package Manager
59 @author The GNU Guix Developers
62 @vskip 0pt plus 1filll
63 Edition @value{EDITION} @*
71 @c *********************************************************************
75 This document describes GNU Guix version @value{VERSION}, a functional
76 package management tool written for the GNU system.
79 * Introduction:: What is Guix about?
80 * Installation:: Installing Guix.
81 * Package Management:: Package installation, upgrade, etc.
82 * Emacs Interface:: Using Guix from Emacs.
83 * Programming Interface:: Using Guix in Scheme.
84 * Utilities:: Package management commands.
85 * GNU Distribution:: Software for your friendly GNU system.
86 * Contributing:: Your help needed!
88 * Acknowledgments:: Thanks!
89 * GNU Free Documentation License:: The license of this manual.
90 * Concept Index:: Concepts.
91 * Programming Index:: Data types, functions, and variables.
94 --- The Detailed Node Listing ---
98 * Binary Installation:: Getting Guix running in no time!
99 * Requirements:: Software needed to build and run Guix.
100 * Running the Test Suite:: Testing Guix.
101 * Setting Up the Daemon:: Preparing the build daemon's environment.
102 * Invoking guix-daemon:: Running the build daemon.
103 * Application Setup:: Application-specific setup.
105 Setting Up the Daemon
107 * Build Environment Setup:: Preparing the isolated build environment.
108 * Daemon Offload Setup:: Offloading builds to remote machines.
112 * Features:: How Guix will make your life brighter.
113 * Invoking guix package:: Package installation, removal, etc.
114 * Substitutes:: Downloading pre-built binaries.
115 * Packages with Multiple Outputs:: Single source package, multiple outputs.
116 * Invoking guix gc:: Running the garbage collector.
117 * Invoking guix pull:: Fetching the latest Guix and distribution.
118 * Invoking guix archive:: Exporting and importing store files.
122 * Initial Setup: Emacs Initial Setup. Preparing @file{~/.emacs}.
123 * Package Management: Emacs Package Management. Managing packages and generations.
124 * Licenses: Emacs Licenses. Interface for licenses of Guix packages.
125 * Package Source Locations: Emacs Package Locations. Interface for package location files.
126 * Popup Interface: Emacs Popup Interface. Magit-like interface for guix commands.
127 * Prettify Mode: Emacs Prettify. Abbreviating @file{/gnu/store/@dots{}} file names.
128 * Build Log Mode: Emacs Build Log. Highlighting Guix build logs.
129 * Completions: Emacs Completions. Completing @command{guix} shell command.
130 * Development: Emacs Development. Tools for Guix developers.
131 * Hydra: Emacs Hydra. Interface for Guix build farm.
133 Programming Interface
135 * Defining Packages:: Defining new packages.
136 * Build Systems:: Specifying how packages are built.
137 * The Store:: Manipulating the package store.
138 * Derivations:: Low-level interface to package derivations.
139 * The Store Monad:: Purely functional interface to the store.
140 * G-Expressions:: Manipulating build expressions.
144 * package Reference:: The package data type.
145 * origin Reference:: The origin data type.
149 * Invoking guix build:: Building packages from the command line.
150 * Invoking guix edit:: Editing package definitions.
151 * Invoking guix download:: Downloading a file and printing its hash.
152 * Invoking guix hash:: Computing the cryptographic hash of a file.
153 * Invoking guix import:: Importing package definitions.
154 * Invoking guix refresh:: Updating package definitions.
155 * Invoking guix lint:: Finding errors in package definitions.
156 * Invoking guix size:: Profiling disk usage.
157 * Invoking guix graph:: Visualizing the graph of packages.
158 * Invoking guix environment:: Setting up development environments.
159 * Invoking guix publish:: Sharing substitutes.
160 * Invoking guix challenge:: Challenging substitute servers.
161 * Invoking guix container:: Process isolation.
163 Invoking @command{guix build}
165 * Common Build Options:: Build options for most commands.
166 * Package Transformation Options:: Creating variants of packages.
167 * Additional Build Options:: Options specific to 'guix build'.
171 * System Installation:: Installing the whole operating system.
172 * System Configuration:: Configuring the operating system.
173 * Installing Debugging Files:: Feeding the debugger.
174 * Security Updates:: Deploying security fixes quickly.
175 * Package Modules:: Packages from the programmer's viewpoint.
176 * Packaging Guidelines:: Growing the distribution.
177 * Bootstrapping:: GNU/Linux built from scratch.
178 * Porting:: Targeting another platform or kernel.
182 * Limitations:: What you can expect.
183 * Hardware Considerations:: Supported hardware.
184 * USB Stick Installation:: Preparing the installation medium.
185 * Preparing for Installation:: Networking, partitioning, etc.
186 * Proceeding with the Installation:: The real thing.
187 * Building the Installation Image:: How this comes to be.
191 * Using the Configuration System:: Customizing your GNU system.
192 * operating-system Reference:: Detail of operating-system declarations.
193 * File Systems:: Configuring file system mounts.
194 * Mapped Devices:: Block device extra processing.
195 * User Accounts:: Specifying user accounts.
196 * Locales:: Language and cultural convention settings.
197 * Services:: Specifying system services.
198 * Setuid Programs:: Programs running with root privileges.
199 * X.509 Certificates:: Authenticating HTTPS servers.
200 * Name Service Switch:: Configuring libc's name service switch.
201 * Initial RAM Disk:: Linux-Libre bootstrapping.
202 * GRUB Configuration:: Configuring the boot loader.
203 * Invoking guix system:: Instantiating a system configuration.
204 * Running GuixSD in a VM:: How to run GuixSD in a virtual machine.
205 * Defining Services:: Adding new service definitions.
209 * Base Services:: Essential system services.
210 * Scheduled Job Execution:: The mcron service.
211 * Networking Services:: Network setup, SSH daemon, etc.
212 * X Window:: Graphical display.
213 * Desktop Services:: D-Bus and desktop services.
214 * Database Services:: SQL databases.
215 * Mail Services:: IMAP, POP3, SMTP, and all that.
216 * Web Services:: Web servers.
217 * Various Services:: Other services.
221 * Service Composition:: The model for composing services.
222 * Service Types and Services:: Types and services.
223 * Service Reference:: API reference.
224 * Shepherd Services:: A particular type of service.
228 * Software Freedom:: What may go into the distribution.
229 * Package Naming:: What's in a name?
230 * Version Numbers:: When the name is not enough.
231 * Synopses and Descriptions:: Helping users find the right package.
232 * Python Modules:: Taming the snake.
233 * Perl Modules:: Little pearls.
234 * Java Packages:: Coffee break.
235 * Fonts:: Fond of fonts.
239 * Building from Git:: The latest and greatest.
240 * Running Guix Before It Is Installed:: Hacker tricks.
241 * The Perfect Setup:: The right tools.
242 * Coding Style:: Hygiene of the contributor.
243 * Submitting Patches:: Share your work.
247 * Programming Paradigm:: How to compose your elements.
248 * Modules:: Where to store your code?
249 * Data Types and Pattern Matching:: Implementing data structures.
250 * Formatting Code:: Writing conventions.
255 @c *********************************************************************
257 @chapter Introduction
260 GNU Guix@footnote{``Guix'' is pronounced like ``geeks'', or ``ɡiːks''
261 using the international phonetic alphabet (IPA).} is a package
262 management tool for the GNU system. Guix makes it easy for unprivileged
263 users to install, upgrade, or remove packages, to roll back to a
264 previous package set, to build packages from source, and generally
265 assists with the creation and maintenance of software environments.
267 @cindex user interfaces
268 Guix provides a command-line package management interface
269 (@pxref{Invoking guix package}), a set of command-line utilities
270 (@pxref{Utilities}), a visual user interface in Emacs (@pxref{Emacs
271 Interface}), as well as Scheme programming interfaces
272 (@pxref{Programming Interface}).
274 Its @dfn{build daemon} is responsible for building packages on behalf of
275 users (@pxref{Setting Up the Daemon}) and for downloading pre-built
276 binaries from authorized sources (@pxref{Substitutes}).
278 @cindex extensibility of the distribution
279 @cindex customization of packages
280 Guix includes package definitions for many GNU and non-GNU packages, all
281 of which @uref{https://www.gnu.org/philosophy/free-sw.html, respect the
282 user's computing freedom}. It is @emph{extensible}: users can write
283 their own package definitions (@pxref{Defining Packages}) and make them
284 available as independent package modules (@pxref{Package Modules}). It
285 is also @emph{customizable}: users can @emph{derive} specialized package
286 definitions from existing ones, including from the command line
287 (@pxref{Package Transformation Options}).
289 @cindex Guix System Distribution
291 You can install GNU@tie{}Guix on top of an existing GNU/Linux system
292 where it complements the available tools without interference
293 (@pxref{Installation}), or you can use it as part of the standalone
294 @dfn{Guix System Distribution} or GuixSD (@pxref{GNU Distribution}).
295 With GNU@tie{}GuixSD, you @emph{declare} all aspects of the operating
296 system configuration and Guix takes care of instantiating the
297 configuration in a transactional, reproducible, and stateless fashion
298 (@pxref{System Configuration}).
300 @cindex functional package management
301 Under the hood, Guix implements the @dfn{functional package management}
302 discipline pioneered by Nix (@pxref{Acknowledgments}).
303 In Guix, the package build and installation process is seen
304 as a @emph{function}, in the mathematical sense. That function takes inputs,
305 such as build scripts, a compiler, and libraries, and
306 returns an installed package. As a pure function, its result depends
307 solely on its inputs---for instance, it cannot refer to software or
308 scripts that were not explicitly passed as inputs. A build function
309 always produces the same result when passed a given set of inputs. It
310 cannot alter the environment of the running system in
311 any way; for instance, it cannot create, modify, or delete files outside
312 of its build and installation directories. This is achieved by running
313 build processes in isolated environments (or @dfn{containers}), where only their
314 explicit inputs are visible.
317 The result of package build functions is @dfn{cached} in the file
318 system, in a special directory called @dfn{the store} (@pxref{The
319 Store}). Each package is installed in a directory of its own in the
320 store---by default under @file{/gnu/store}. The directory name contains
321 a hash of all the inputs used to build that package; thus, changing an
322 input yields a different directory name.
324 This approach is the foundation for the salient features of Guix: support
325 for transactional package upgrade and rollback, per-user installation, and
326 garbage collection of packages (@pxref{Features}).
329 @c *********************************************************************
331 @chapter Installation
333 GNU Guix is available for download from its website at
334 @url{http://www.gnu.org/software/guix/}. This section describes the
335 software requirements of Guix, as well as how to install it and get
338 Note that this section is concerned with the installation of the package
339 manager, which can be done on top of a running GNU/Linux system. If,
340 instead, you want to install the complete GNU operating system,
341 @pxref{System Installation}.
343 @cindex foreign distro
344 When installed on a running GNU/Linux system---thereafter called a
345 @dfn{foreign distro}---GNU@tie{}Guix complements the available tools
346 without interference. Its data lives exclusively in two directories,
347 usually @file{/gnu/store} and @file{/var/guix}; other files on your
348 system, such as @file{/etc}, are left untouched.
351 * Binary Installation:: Getting Guix running in no time!
352 * Requirements:: Software needed to build and run Guix.
353 * Running the Test Suite:: Testing Guix.
354 * Setting Up the Daemon:: Preparing the build daemon's environment.
355 * Invoking guix-daemon:: Running the build daemon.
356 * Application Setup:: Application-specific setup.
359 @node Binary Installation
360 @section Binary Installation
362 This section describes how to install Guix on an arbitrary system from a
363 self-contained tarball providing binaries for Guix and for all its
364 dependencies. This is often quicker than installing from source, which
365 is described in the next sections. The only requirement is to have
368 Installing goes along these lines:
372 Download the binary tarball from
373 @indicateurl{ftp://alpha.gnu.org/gnu/guix/guix-binary-@value{VERSION}.@var{system}.tar.xz},
374 where @var{system} is @code{x86_64-linux} for an @code{x86_64} machine
375 already running the kernel Linux, and so on.
377 Make sure to download the associated @file{.sig} file and to verify the
378 authenticity of the tarball against it, along these lines:
381 $ wget ftp://alpha.gnu.org/gnu/guix/guix-binary-@value{VERSION}.@var{system}.tar.xz.sig
382 $ gpg --verify guix-binary-@value{VERSION}.@var{system}.tar.xz.sig
385 If that command fails because you do not have the required public key,
386 then run this command to import it:
389 $ gpg --keyserver pgp.mit.edu --recv-keys 090B11993D9AEBB5
393 and rerun the @code{gpg --verify} command.
400 # tar --warning=no-timestamp -xf \
401 guix-binary-@value{VERSION}.@var{system}.tar.xz
402 # mv var/guix /var/ && mv gnu /
405 This creates @file{/gnu/store} (@pxref{The Store}) and @file{/var/guix}.
406 The latter contains a ready-to-use profile for @code{root} (see next
409 Do @emph{not} unpack the tarball on a working Guix system since that
410 would overwrite its own essential files.
412 The @code{--warning=no-timestamp} option makes sure GNU@tie{}tar does
413 not emit warnings about ``implausibly old time stamps'' (such
414 warnings were triggered by GNU@tie{}tar 1.26 and older; recent
416 They stem from the fact that all the
417 files in the archive have their modification time set to zero (which
418 means January 1st, 1970.) This is done on purpose to make sure the
419 archive content is independent of its creation time, thus making it
423 Make @code{root}'s profile available under @file{~/.guix-profile}:
426 # ln -sf /var/guix/profiles/per-user/root/guix-profile \
431 Create the group and user accounts for build users as explained below
432 (@pxref{Build Environment Setup}).
435 Run the daemon, and set it to automatically start on boot.
437 If your host distro uses the systemd init system, this can be achieved
441 # cp ~root/.guix-profile/lib/systemd/system/guix-daemon.service \
443 # systemctl start guix-daemon && systemctl enable guix-daemon
446 If your host distro uses the Upstart init system:
449 # cp ~root/.guix-profile/lib/upstart/system/guix-daemon.conf /etc/init/
453 Otherwise, you can still start the daemon manually with:
456 # ~root/.guix-profile/bin/guix-daemon --build-users-group=guixbuild
460 Make the @command{guix} command available to other users on the machine,
464 # mkdir -p /usr/local/bin
466 # ln -s /var/guix/profiles/per-user/root/guix-profile/bin/guix
469 It is also a good idea to make the Info version of this manual available
473 # mkdir -p /usr/local/share/info
474 # cd /usr/local/share/info
475 # for i in /var/guix/profiles/per-user/root/guix-profile/share/info/* ;
479 That way, assuming @file{/usr/local/share/info} is in the search path,
480 running @command{info guix} will open this manual (@pxref{Other Info
481 Directories,,, texinfo, GNU Texinfo}, for more details on changing the
485 To use substitutes from @code{hydra.gnu.org} or one of its mirrors
486 (@pxref{Substitutes}), authorize them:
489 # guix archive --authorize < ~root/.guix-profile/share/guix/hydra.gnu.org.pub
493 This completes root-level install of Guix. Each user will need to
494 perform additional steps to make their Guix envionment ready for use,
495 @pxref{Application Setup}.
497 You can confirm that Guix is working by installing a sample package into
501 # guix package -i hello
504 The @code{guix} package must remain available in @code{root}'s profile,
505 or it would become subject to garbage collection---in which case you
506 would find yourself badly handicapped by the lack of the @command{guix}
507 command. In other words, do not remove @code{guix} by running
508 @code{guix package -r guix}.
510 The binary installation tarball can be (re)produced and verified simply
511 by running the following command in the Guix source tree:
514 make guix-binary.@var{system}.tar.xz
519 @section Requirements
521 This section lists requirements when building Guix from source. The
522 build procedure for Guix is the same as for other GNU software, and is
523 not covered here. Please see the files @file{README} and @file{INSTALL}
524 in the Guix source tree for additional details.
526 GNU Guix depends on the following packages:
529 @item @url{http://gnu.org/software/guile/, GNU Guile}, version 2.0.7 or later;
530 @item @url{http://gnupg.org/, GNU libgcrypt};
531 @item @url{http://www.gnu.org/software/make/, GNU Make}.
534 The following dependencies are optional:
538 Installing @uref{http://gnutls.org/, GnuTLS-Guile} will allow you to
539 access @code{https} URLs for substitutes, which is highly recommended
540 (@pxref{Substitutes}). It also allows you to access HTTPS URLs with the
541 @command{guix download} command (@pxref{Invoking guix download}), the
542 @command{guix import pypi} command, and the @command{guix import cpan}
543 command. @xref{Guile Preparations, how to install the GnuTLS bindings
544 for Guile,, gnutls-guile, GnuTLS-Guile}.
548 @url{http://savannah.nongnu.org/projects/guile-json/, Guile-JSON} will
549 allow you to use the @command{guix import pypi} command (@pxref{Invoking
550 guix import}). It is of
551 interest primarily for developers and not for casual users.
554 When @url{http://zlib.net, zlib} is available, @command{guix publish}
555 can compress build byproducts (@pxref{Invoking guix publish}).
558 Unless @code{--disable-daemon} was passed to @command{configure}, the
559 following packages are also needed:
562 @item @url{http://sqlite.org, SQLite 3};
563 @item @url{http://www.bzip.org, libbz2};
564 @item @url{http://gcc.gnu.org, GCC's g++}, with support for the
568 When configuring Guix on a system that already has a Guix installation,
569 be sure to specify the same state directory as the existing installation
570 using the @code{--localstatedir} option of the @command{configure}
571 script (@pxref{Directory Variables, @code{localstatedir},, standards,
572 GNU Coding Standards}). The @command{configure} script protects against
573 unintended misconfiguration of @var{localstatedir} so you do not
574 inadvertently corrupt your store (@pxref{The Store}).
576 When a working installation of @url{http://nixos.org/nix/, the Nix package
577 manager} is available, you
578 can instead configure Guix with @code{--disable-daemon}. In that case,
579 Nix replaces the three dependencies above.
581 Guix is compatible with Nix, so it is possible to share the same store
582 between both. To do so, you must pass @command{configure} not only the
583 same @code{--with-store-dir} value, but also the same
584 @code{--localstatedir} value. The latter is essential because it
585 specifies where the database that stores metadata about the store is
586 located, among other things. The default values for Nix are
587 @code{--with-store-dir=/nix/store} and @code{--localstatedir=/nix/var}.
588 Note that @code{--disable-daemon} is not required if
589 your goal is to share the store with Nix.
591 @node Running the Test Suite
592 @section Running the Test Suite
594 After a successful @command{configure} and @code{make} run, it is a good
595 idea to run the test suite. It can help catch issues with the setup or
596 environment, or bugs in Guix itself---and really, reporting test
597 failures is a good way to help improve the software. To run the test
604 Test cases can run in parallel: you can use the @code{-j} option of
605 GNU@tie{}make to speed things up. The first run may take a few minutes
606 on a recent machine; subsequent runs will be faster because the store
607 that is created for test purposes will already have various things in
610 It is also possible to run a subset of the tests by defining the
611 @code{TESTS} makefile variable as in this example:
614 make check TESTS="tests/store.scm tests/cpio.scm"
617 By default, tests results are displayed at a file level. In order to
618 see the details of every individual test cases, it is possible to define
619 the @code{SCM_LOG_DRIVER_FLAGS} makefile variable as in this example:
622 make check TESTS="tests/base64.scm" SCM_LOG_DRIVER_FLAGS="--brief=no"
625 Upon failure, please email @email{bug-guix@@gnu.org} and attach the
626 @file{test-suite.log} file. Please specify the Guix version being used
627 as well as version numbers of the dependencies (@pxref{Requirements}) in
630 Guix also comes with a whole-system test suite that tests complete
631 GuixSD operating system instances. It can only run on systems where
632 Guix is already installed, using:
639 or, again, by defining @code{TESTS} to select a subset of tests to run:
642 make check-system TESTS="basic mcron"
645 These system tests are defined in the @code{(gnu tests @dots{})}
646 modules. They work by running the operating systems under test with
647 lightweight instrumentation in a virtual machine (VM). They can be
648 computationally intensive or rather cheap, depending on whether
649 substitutes are available for their dependencies (@pxref{Substitutes}).
650 Some of them require a lot of storage space to hold VM images.
652 Again in case of test failures, please send @email{bug-guix@@gnu.org}
655 @node Setting Up the Daemon
656 @section Setting Up the Daemon
659 Operations such as building a package or running the garbage collector
660 are all performed by a specialized process, the @dfn{build daemon}, on
661 behalf of clients. Only the daemon may access the store and its
662 associated database. Thus, any operation that manipulates the store
663 goes through the daemon. For instance, command-line tools such as
664 @command{guix package} and @command{guix build} communicate with the
665 daemon (@i{via} remote procedure calls) to instruct it what to do.
667 The following sections explain how to prepare the build daemon's
668 environment. See also @ref{Substitutes}, for information on how to allow
669 the daemon to download pre-built binaries.
672 * Build Environment Setup:: Preparing the isolated build environment.
673 * Daemon Offload Setup:: Offloading builds to remote machines.
676 @node Build Environment Setup
677 @subsection Build Environment Setup
679 In a standard multi-user setup, Guix and its daemon---the
680 @command{guix-daemon} program---are installed by the system
681 administrator; @file{/gnu/store} is owned by @code{root} and
682 @command{guix-daemon} runs as @code{root}. Unprivileged users may use
683 Guix tools to build packages or otherwise access the store, and the
684 daemon will do it on their behalf, ensuring that the store is kept in a
685 consistent state, and allowing built packages to be shared among users.
688 When @command{guix-daemon} runs as @code{root}, you may not want package
689 build processes themselves to run as @code{root} too, for obvious
690 security reasons. To avoid that, a special pool of @dfn{build users}
691 should be created for use by build processes started by the daemon.
692 These build users need not have a shell and a home directory: they will
693 just be used when the daemon drops @code{root} privileges in build
694 processes. Having several such users allows the daemon to launch
695 distinct build processes under separate UIDs, which guarantees that they
696 do not interfere with each other---an essential feature since builds are
697 regarded as pure functions (@pxref{Introduction}).
699 On a GNU/Linux system, a build user pool may be created like this (using
700 Bash syntax and the @code{shadow} commands):
702 @c See http://lists.gnu.org/archive/html/bug-guix/2013-01/msg00239.html
703 @c for why `-G' is needed.
705 # groupadd --system guixbuild
706 # for i in `seq -w 1 10`;
708 useradd -g guixbuild -G guixbuild \
709 -d /var/empty -s `which nologin` \
710 -c "Guix build user $i" --system \
716 The number of build users determines how many build jobs may run in
717 parallel, as specified by the @option{--max-jobs} option
718 (@pxref{Invoking guix-daemon, @option{--max-jobs}}). To use
719 @command{guix system vm} and related commands, you may need to add the
720 build users to the @code{kvm} group so they can access @file{/dev/kvm},
721 using @code{-G guixbuild,kvm} instead of @code{-G guixbuild}
722 (@pxref{Invoking guix system}).
724 The @code{guix-daemon} program may then be run as @code{root} with the
725 following command@footnote{If your machine uses the systemd init system,
726 dropping the @file{@var{prefix}/lib/systemd/system/guix-daemon.service}
727 file in @file{/etc/systemd/system} will ensure that
728 @command{guix-daemon} is automatically started. Similarly, if your
729 machine uses the Upstart init system, drop the
730 @file{@var{prefix}/lib/upstart/system/guix-daemon.conf}
731 file in @file{/etc/init}.}:
734 # guix-daemon --build-users-group=guixbuild
739 This way, the daemon starts build processes in a chroot, under one of
740 the @code{guixbuilder} users. On GNU/Linux, by default, the chroot
741 environment contains nothing but:
743 @c Keep this list in sync with libstore/build.cc! -----------------------
746 a minimal @code{/dev} directory, created mostly independently from the
747 host @code{/dev}@footnote{``Mostly'', because while the set of files
748 that appear in the chroot's @code{/dev} is fixed, most of these files
749 can only be created if the host has them.};
752 the @code{/proc} directory; it only shows the processes of the container
753 since a separate PID name space is used;
756 @file{/etc/passwd} with an entry for the current user and an entry for
760 @file{/etc/group} with an entry for the user's group;
763 @file{/etc/hosts} with an entry that maps @code{localhost} to
767 a writable @file{/tmp} directory.
770 You can influence the directory where the daemon stores build trees
771 @i{via} the @code{TMPDIR} environment variable. However, the build tree
772 within the chroot is always called @file{/tmp/guix-build-@var{name}.drv-0},
773 where @var{name} is the derivation name---e.g., @code{coreutils-8.24}.
774 This way, the value of @code{TMPDIR} does not leak inside build
775 environments, which avoids discrepancies in cases where build processes
776 capture the name of their build tree.
779 The daemon also honors the @code{http_proxy} environment variable for
780 HTTP downloads it performs, be it for fixed-output derivations
781 (@pxref{Derivations}) or for substitutes (@pxref{Substitutes}).
783 If you are installing Guix as an unprivileged user, it is still possible
784 to run @command{guix-daemon} provided you pass @code{--disable-chroot}.
785 However, build processes will not be isolated from one another, and not
786 from the rest of the system. Thus, build processes may interfere with
787 each other, and may access programs, libraries, and other files
788 available on the system---making it much harder to view them as
789 @emph{pure} functions.
792 @node Daemon Offload Setup
793 @subsection Using the Offload Facility
797 When desired, the build daemon can @dfn{offload}
798 derivation builds to other machines
799 running Guix, using the @code{offload} @dfn{build hook}. When that
800 feature is enabled, a list of user-specified build machines is read from
801 @file{/etc/guix/machines.scm}; every time a build is requested, for
802 instance via @code{guix build}, the daemon attempts to offload it to one
803 of the machines that satisfy the constraints of the derivation, in
804 particular its system type---e.g., @file{x86_64-linux}. Missing
805 prerequisites for the build are copied over SSH to the target machine,
806 which then proceeds with the build; upon success the output(s) of the
807 build are copied back to the initial machine.
809 The @file{/etc/guix/machines.scm} file typically looks like this:
813 (name "eightysix.example.org")
814 (system "x86_64-linux")
816 (speed 2.)) ; incredibly fast!
819 (name "meeps.example.org")
820 (system "mips64el-linux")
823 (string-append (getenv "HOME")
824 "/.lsh/identity-for-guix"))))
828 In the example above we specify a list of two build machines, one for
829 the @code{x86_64} architecture and one for the @code{mips64el}
832 In fact, this file is---not surprisingly!---a Scheme file that is
833 evaluated when the @code{offload} hook is started. Its return value
834 must be a list of @code{build-machine} objects. While this example
835 shows a fixed list of build machines, one could imagine, say, using
836 DNS-SD to return a list of potential build machines discovered in the
837 local network (@pxref{Introduction, Guile-Avahi,, guile-avahi, Using
838 Avahi in Guile Scheme Programs}). The @code{build-machine} data type is
841 @deftp {Data Type} build-machine
842 This data type represents build machines to which the daemon may offload
843 builds. The important fields are:
848 The host name of the remote machine.
851 The system type of the remote machine---e.g., @code{"x86_64-linux"}.
854 The user account to use when connecting to the remote machine over SSH.
855 Note that the SSH key pair must @emph{not} be passphrase-protected, to
856 allow non-interactive logins.
860 A number of optional fields may be specified:
865 Port number of SSH server on the machine (default: 22).
868 The SSH private key file to use when connecting to the machine.
870 Currently offloading uses GNU@tie{}lsh as its SSH client
871 (@pxref{Invoking lsh,,, GNU lsh Manual}). Thus, the key file here must
872 be an lsh key file. This may change in the future, though.
874 @item parallel-builds
875 The number of builds that may run in parallel on the machine (1 by
879 A ``relative speed factor''. The offload scheduler will tend to prefer
880 machines with a higher speed factor.
883 A list of strings denoting specific features supported by the machine.
884 An example is @code{"kvm"} for machines that have the KVM Linux modules
885 and corresponding hardware support. Derivations can request features by
886 name, and they will be scheduled on matching build machines.
891 The @code{guix} command must be in the search path on the build
892 machines, since offloading works by invoking the @code{guix archive} and
893 @code{guix build} commands. In addition, the Guix modules must be in
894 @code{$GUILE_LOAD_PATH} on the build machine---you can check whether
895 this is the case by running:
898 lsh build-machine guile -c "'(use-modules (guix config))'"
901 There is one last thing to do once @file{machines.scm} is in place. As
902 explained above, when offloading, files are transferred back and forth
903 between the machine stores. For this to work, you first need to
904 generate a key pair on each machine to allow the daemon to export signed
905 archives of files from the store (@pxref{Invoking guix archive}):
908 # guix archive --generate-key
912 Each build machine must authorize the key of the master machine so that
913 it accepts store items it receives from the master:
916 # guix archive --authorize < master-public-key.txt
920 Likewise, the master machine must authorize the key of each build machine.
922 All the fuss with keys is here to express pairwise mutual trust
923 relations between the master and the build machines. Concretely, when
924 the master receives files from a build machine (and @i{vice versa}), its
925 build daemon can make sure they are genuine, have not been tampered
926 with, and that they are signed by an authorized key.
929 @node Invoking guix-daemon
930 @section Invoking @command{guix-daemon}
932 The @command{guix-daemon} program implements all the functionality to
933 access the store. This includes launching build processes, running the
934 garbage collector, querying the availability of a build result, etc. It
935 is normally run as @code{root} like this:
938 # guix-daemon --build-users-group=guixbuild
942 For details on how to set it up, @pxref{Setting Up the Daemon}.
945 @cindex container, build environment
946 @cindex build environment
947 @cindex reproducible builds
948 By default, @command{guix-daemon} launches build processes under
949 different UIDs, taken from the build group specified with
950 @code{--build-users-group}. In addition, each build process is run in a
951 chroot environment that only contains the subset of the store that the
952 build process depends on, as specified by its derivation
953 (@pxref{Programming Interface, derivation}), plus a set of specific
954 system directories. By default, the latter contains @file{/dev} and
955 @file{/dev/pts}. Furthermore, on GNU/Linux, the build environment is a
956 @dfn{container}: in addition to having its own file system tree, it has
957 a separate mount name space, its own PID name space, network name space,
958 etc. This helps achieve reproducible builds (@pxref{Features}).
960 When the daemon performs a build on behalf of the user, it creates a
961 build directory under @file{/tmp} or under the directory specified by
962 its @code{TMPDIR} environment variable; this directory is shared with
963 the container for the duration of the build. Be aware that using a
964 directory other than @file{/tmp} can affect build results---for example,
965 with a longer directory name, a build process that uses Unix-domain
966 sockets might hit the name length limitation for @code{sun_path}, which
967 it would otherwise not hit.
969 The build directory is automatically deleted upon completion, unless the
970 build failed and the client specified @option{--keep-failed}
971 (@pxref{Invoking guix build, @option{--keep-failed}}).
973 The following command-line options are supported:
976 @item --build-users-group=@var{group}
977 Take users from @var{group} to run build processes (@pxref{Setting Up
978 the Daemon, build users}).
980 @item --no-substitutes
982 Do not use substitutes for build products. That is, always build things
983 locally instead of allowing downloads of pre-built binaries
984 (@pxref{Substitutes}).
986 By default substitutes are used, unless the client---such as the
987 @command{guix package} command---is explicitly invoked with
988 @code{--no-substitutes}.
990 When the daemon runs with @code{--no-substitutes}, clients can still
991 explicitly enable substitution @i{via} the @code{set-build-options}
992 remote procedure call (@pxref{The Store}).
994 @item --substitute-urls=@var{urls}
995 @anchor{daemon-substitute-urls}
996 Consider @var{urls} the default whitespace-separated list of substitute
997 source URLs. When this option is omitted,
998 @indicateurl{https://mirror.hydra.gnu.org https://hydra.gnu.org} is used
999 (@code{mirror.hydra.gnu.org} is a mirror of @code{hydra.gnu.org}).
1001 This means that substitutes may be downloaded from @var{urls}, as long
1002 as they are signed by a trusted signature (@pxref{Substitutes}).
1005 @item --no-build-hook
1006 Do not use the @dfn{build hook}.
1008 The build hook is a helper program that the daemon can start and to
1009 which it submits build requests. This mechanism is used to offload
1010 builds to other machines (@pxref{Daemon Offload Setup}).
1012 @item --cache-failures
1013 Cache build failures. By default, only successful builds are cached.
1015 When this option is used, @command{guix gc --list-failures} can be used
1016 to query the set of store items marked as failed; @command{guix gc
1017 --clear-failures} removes store items from the set of cached failures.
1018 @xref{Invoking guix gc}.
1020 @item --cores=@var{n}
1022 Use @var{n} CPU cores to build each derivation; @code{0} means as many
1025 The default value is @code{0}, but it may be overridden by clients, such
1026 as the @code{--cores} option of @command{guix build} (@pxref{Invoking
1029 The effect is to define the @code{NIX_BUILD_CORES} environment variable
1030 in the build process, which can then use it to exploit internal
1031 parallelism---for instance, by running @code{make -j$NIX_BUILD_CORES}.
1033 @item --max-jobs=@var{n}
1035 Allow at most @var{n} build jobs in parallel. The default value is
1036 @code{1}. Setting it to @code{0} means that no builds will be performed
1037 locally; instead, the daemon will offload builds (@pxref{Daemon Offload
1038 Setup}), or simply fail.
1040 @item --rounds=@var{N}
1041 Build each derivation @var{n} times in a row, and raise an error if
1042 consecutive build results are not bit-for-bit identical. Note that this
1043 setting can be overridden by clients such as @command{guix build}
1044 (@pxref{Invoking guix build}).
1046 When used in conjunction with @option{--keep-failed}, the differing
1047 output is kept in the store, under @file{/gnu/store/@dots{}-check}.
1048 This makes it easy to look for differences between the two results.
1051 Produce debugging output.
1053 This is useful to debug daemon start-up issues, but then it may be
1054 overridden by clients, for example the @code{--verbosity} option of
1055 @command{guix build} (@pxref{Invoking guix build}).
1057 @item --chroot-directory=@var{dir}
1058 Add @var{dir} to the build chroot.
1060 Doing this may change the result of build processes---for instance if
1061 they use optional dependencies found in @var{dir} when it is available,
1062 and not otherwise. For that reason, it is not recommended to do so.
1063 Instead, make sure that each derivation declares all the inputs that it
1066 @item --disable-chroot
1067 Disable chroot builds.
1069 Using this option is not recommended since, again, it would allow build
1070 processes to gain access to undeclared dependencies. It is necessary,
1071 though, when @command{guix-daemon} is running under an unprivileged user
1074 @item --disable-log-compression
1075 Disable compression of the build logs.
1077 Unless @code{--lose-logs} is used, all the build logs are kept in the
1078 @var{localstatedir}. To save space, the daemon automatically compresses
1079 them with bzip2 by default. This option disables that.
1081 @item --disable-deduplication
1082 @cindex deduplication
1083 Disable automatic file ``deduplication'' in the store.
1085 By default, files added to the store are automatically ``deduplicated'':
1086 if a newly added file is identical to another one found in the store,
1087 the daemon makes the new file a hard link to the other file. This can
1088 noticeably reduce disk usage, at the expense of slightly increased
1089 input/output load at the end of a build process. This option disables
1092 @item --gc-keep-outputs[=yes|no]
1093 Tell whether the garbage collector (GC) must keep outputs of live
1096 When set to ``yes'', the GC will keep the outputs of any live derivation
1097 available in the store---the @code{.drv} files. The default is ``no'',
1098 meaning that derivation outputs are kept only if they are GC roots.
1100 @item --gc-keep-derivations[=yes|no]
1101 Tell whether the garbage collector (GC) must keep derivations
1102 corresponding to live outputs.
1104 When set to ``yes'', as is the case by default, the GC keeps
1105 derivations---i.e., @code{.drv} files---as long as at least one of their
1106 outputs is live. This allows users to keep track of the origins of
1107 items in their store. Setting it to ``no'' saves a bit of disk space.
1109 Note that when both @code{--gc-keep-derivations} and
1110 @code{--gc-keep-outputs} are used, the effect is to keep all the build
1111 prerequisites (the sources, compiler, libraries, and other build-time
1112 tools) of live objects in the store, regardless of whether these
1113 prerequisites are live. This is convenient for developers since it
1114 saves rebuilds or downloads.
1116 @item --impersonate-linux-2.6
1117 On Linux-based systems, impersonate Linux 2.6. This means that the
1118 kernel's @code{uname} system call will report 2.6 as the release number.
1120 This might be helpful to build programs that (usually wrongfully) depend
1121 on the kernel version number.
1124 Do not keep build logs. By default they are kept under
1125 @code{@var{localstatedir}/guix/log}.
1127 @item --system=@var{system}
1128 Assume @var{system} as the current system type. By default it is the
1129 architecture/kernel pair found at configure time, such as
1130 @code{x86_64-linux}.
1132 @item --listen=@var{socket}
1133 Listen for connections on @var{socket}, the file name of a Unix-domain
1134 socket. The default socket is
1135 @file{@var{localstatedir}/daemon-socket/socket}. This option is only
1136 useful in exceptional circumstances, such as if you need to run several
1137 daemons on the same machine.
1141 @node Application Setup
1142 @section Application Setup
1144 @cindex foreign distro
1145 When using Guix on top of GNU/Linux distribution other than GuixSD---a
1146 so-called @dfn{foreign distro}---a few additional steps are needed to
1147 get everything in place. Here are some of them.
1151 @anchor{locales-and-locpath}
1152 @cindex locales, when not on GuixSD
1154 @vindex GUIX_LOCPATH
1155 Packages installed @i{via} Guix will not use the locale data of the
1156 host system. Instead, you must first install one of the locale packages
1157 available with Guix and then define the @code{GUIX_LOCPATH} environment
1161 $ guix package -i glibc-locales
1162 $ export GUIX_LOCPATH=$HOME/.guix-profile/lib/locale
1165 Note that the @code{glibc-locales} package contains data for all the
1166 locales supported by the GNU@tie{}libc and weighs in at around
1167 110@tie{}MiB. Alternatively, the @code{glibc-utf8-locales} is smaller but
1168 limited to a few UTF-8 locales.
1170 The @code{GUIX_LOCPATH} variable plays a role similar to @code{LOCPATH}
1171 (@pxref{Locale Names, @code{LOCPATH},, libc, The GNU C Library Reference
1172 Manual}). There are two important differences though:
1176 @code{GUIX_LOCPATH} is honored only by the libc in Guix, and not by the libc
1177 provided by foreign distros. Thus, using @code{GUIX_LOCPATH} allows you
1178 to make sure the programs of the foreign distro will not end up loading
1179 incompatible locale data.
1182 libc suffixes each entry of @code{GUIX_LOCPATH} with @code{/X.Y}, where
1183 @code{X.Y} is the libc version---e.g., @code{2.22}. This means that,
1184 should your Guix profile contain a mixture of programs linked against
1185 different libc version, each libc version will only try to load locale
1186 data in the right format.
1189 This is important because the locale data format used by different libc
1190 versions may be incompatible.
1192 @subsection X11 Fonts
1194 The majority of graphical applications use Fontconfig to locate and
1195 load fonts and perform X11-client-side rendering. The @code{fontconfig}
1196 package in Guix looks for fonts in @file{$HOME/.guix-profile}
1197 by default. Thus, to allow graphical applications installed with Guix
1198 to display fonts, you have to install fonts with Guix as well.
1199 Essential font packages include @code{gs-fonts}, @code{font-dejavu}, and
1200 @code{font-gnu-freefont-ttf}.
1202 To display text written in Chinese languages, Japanese, or Korean in
1203 graphical applications, consider installing
1204 @code{font-adobe-source-han-sans} or @code{font-wqy-zenhei}. The former
1205 has multiple outputs, one per language family (@pxref{Packages with
1206 Multiple Outputs}). For instance, the following command installs fonts
1207 for Chinese languages:
1210 guix package -i font-adobe-source-han-sans:cn
1213 Older programs such as @command{xterm} do not use Fontconfig and instead
1214 rely on server-side font rendering. Such programs require to specify a
1215 full name of a font using XLFD (X Logical Font Description), like this:
1218 -*-dejavu sans-medium-r-normal-*-*-100-*-*-*-*-*-1
1221 To be able to use such full names for the TrueType fonts installed in
1222 your Guix profile, you need to extend the font path of the X server:
1225 xset +fp ~/.guix-profile/share/fonts/truetype
1228 After that, you can run @code{xlsfonts} (from @code{xlsfonts} package)
1229 to make sure your TrueType fonts are listed there.
1231 @subsection X.509 Certificates
1233 The @code{nss-certs} package provides X.509 certificates, which allow
1234 programs to authenticate Web servers accessed over HTTPS.
1236 When using Guix on a foreign distro, you can install this package and
1237 define the relevant environment variables so that packages know where to
1238 look for certificates. @pxref{X.509 Certificates}, for detailed
1241 @subsection Emacs Packages
1243 When you install Emacs packages with Guix, the elisp files may be placed
1244 either in @file{$HOME/.guix-profile/share/emacs/site-lisp/} or in
1246 @file{$HOME/.guix-profile/share/emacs/site-lisp/guix.d/}. The latter
1247 directory exists because potentially there may exist thousands of Emacs
1248 packages and storing all their files in a single directory may be not
1249 reliable (because of name conflicts). So we think using a separate
1250 directory for each package is a good idea. It is very similar to how
1251 the Emacs package system organizes the file structure (@pxref{Package
1252 Files,,, emacs, The GNU Emacs Manual}).
1254 By default, Emacs (installed with Guix) ``knows'' where these packages
1255 are placed, so you do not need to perform any configuration. If, for
1256 some reason, you want to avoid auto-loading Emacs packages installed
1257 with Guix, you can do so by running Emacs with @code{--no-site-file}
1258 option (@pxref{Init File,,, emacs, The GNU Emacs Manual}).
1262 @c *********************************************************************
1263 @node Package Management
1264 @chapter Package Management
1266 The purpose of GNU Guix is to allow users to easily install, upgrade, and
1267 remove software packages, without having to know about their build
1268 procedures or dependencies. Guix also goes beyond this obvious set of
1271 This chapter describes the main features of Guix, as well as the package
1272 management tools it provides. Two user interfaces are provided for
1273 routine package management tasks: A command-line interface described below
1274 (@pxref{Invoking guix package, @code{guix package}}), as well as a visual user
1275 interface in Emacs described in a subsequent chapter (@pxref{Emacs Interface}).
1278 * Features:: How Guix will make your life brighter.
1279 * Invoking guix package:: Package installation, removal, etc.
1280 * Substitutes:: Downloading pre-built binaries.
1281 * Packages with Multiple Outputs:: Single source package, multiple outputs.
1282 * Invoking guix gc:: Running the garbage collector.
1283 * Invoking guix pull:: Fetching the latest Guix and distribution.
1284 * Invoking guix archive:: Exporting and importing store files.
1290 When using Guix, each package ends up in the @dfn{package store}, in its
1291 own directory---something that resembles
1292 @file{/gnu/store/xxx-package-1.2}, where @code{xxx} is a base32 string
1293 (note that Guix comes with an Emacs extension to shorten those file
1294 names, @pxref{Emacs Prettify}.)
1296 Instead of referring to these directories, users have their own
1297 @dfn{profile}, which points to the packages that they actually want to
1298 use. These profiles are stored within each user's home directory, at
1299 @code{$HOME/.guix-profile}.
1301 For example, @code{alice} installs GCC 4.7.2. As a result,
1302 @file{/home/alice/.guix-profile/bin/gcc} points to
1303 @file{/gnu/store/@dots{}-gcc-4.7.2/bin/gcc}. Now, on the same machine,
1304 @code{bob} had already installed GCC 4.8.0. The profile of @code{bob}
1305 simply continues to point to
1306 @file{/gnu/store/@dots{}-gcc-4.8.0/bin/gcc}---i.e., both versions of GCC
1307 coexist on the same system without any interference.
1309 The @command{guix package} command is the central tool to manage
1310 packages (@pxref{Invoking guix package}). It operates on the per-user
1311 profiles, and can be used @emph{with normal user privileges}.
1313 The command provides the obvious install, remove, and upgrade
1314 operations. Each invocation is actually a @emph{transaction}: either
1315 the specified operation succeeds, or nothing happens. Thus, if the
1316 @command{guix package} process is terminated during the transaction,
1317 or if a power outage occurs during the transaction, then the user's
1318 profile remains in its previous state, and remains usable.
1320 In addition, any package transaction may be @emph{rolled back}. So, if,
1321 for example, an upgrade installs a new version of a package that turns
1322 out to have a serious bug, users may roll back to the previous instance
1323 of their profile, which was known to work well. Similarly, the global
1324 system configuration on GuixSD is subject to
1325 transactional upgrades and roll-back
1326 (@pxref{Using the Configuration System}).
1328 All packages in the package store may be @emph{garbage-collected}.
1329 Guix can determine which packages are still referenced by user
1330 profiles, and remove those that are provably no longer referenced
1331 (@pxref{Invoking guix gc}). Users may also explicitly remove old
1332 generations of their profile so that the packages they refer to can be
1335 @cindex reproducibility
1336 @cindex reproducible builds
1337 Finally, Guix takes a @dfn{purely functional} approach to package
1338 management, as described in the introduction (@pxref{Introduction}).
1339 Each @file{/gnu/store} package directory name contains a hash of all the
1340 inputs that were used to build that package---compiler, libraries, build
1341 scripts, etc. This direct correspondence allows users to make sure a
1342 given package installation matches the current state of their
1343 distribution. It also helps maximize @dfn{build reproducibility}:
1344 thanks to the isolated build environments that are used, a given build
1345 is likely to yield bit-identical files when performed on different
1346 machines (@pxref{Invoking guix-daemon, container}).
1349 This foundation allows Guix to support @dfn{transparent binary/source
1350 deployment}. When a pre-built binary for a @file{/gnu/store} item is
1351 available from an external source---a @dfn{substitute}, Guix just
1352 downloads it and unpacks it;
1353 otherwise, it builds the package from source, locally
1354 (@pxref{Substitutes}). Because build results are usually bit-for-bit
1355 reproducible, users do not have to trust servers that provide
1356 substitutes: they can force a local build and @emph{challenge} providers
1357 (@pxref{Invoking guix challenge}).
1359 Control over the build environment is a feature that is also useful for
1360 developers. The @command{guix environment} command allows developers of
1361 a package to quickly set up the right development environment for their
1362 package, without having to manually install the dependencies of the
1363 package into their profile (@pxref{Invoking guix environment}).
1365 @node Invoking guix package
1366 @section Invoking @command{guix package}
1368 The @command{guix package} command is the tool that allows users to
1369 install, upgrade, and remove packages, as well as rolling back to
1370 previous configurations. It operates only on the user's own profile,
1371 and works with normal user privileges (@pxref{Features}). Its syntax
1375 guix package @var{options}
1378 Primarily, @var{options} specifies the operations to be performed during
1379 the transaction. Upon completion, a new profile is created, but
1380 previous @dfn{generations} of the profile remain available, should the user
1383 For example, to remove @code{lua} and install @code{guile} and
1384 @code{guile-cairo} in a single transaction:
1387 guix package -r lua -i guile guile-cairo
1390 @command{guix package} also supports a @dfn{declarative approach}
1391 whereby the user specifies the exact set of packages to be available and
1392 passes it @i{via} the @option{--manifest} option
1393 (@pxref{profile-manifest, @option{--manifest}}).
1395 For each user, a symlink to the user's default profile is automatically
1396 created in @file{$HOME/.guix-profile}. This symlink always points to the
1397 current generation of the user's default profile. Thus, users can add
1398 @file{$HOME/.guix-profile/bin} to their @code{PATH} environment
1399 variable, and so on.
1400 @cindex search paths
1401 If you are not using the Guix System Distribution, consider adding the
1402 following lines to your @file{~/.bash_profile} (@pxref{Bash Startup
1403 Files,,, bash, The GNU Bash Reference Manual}) so that newly-spawned
1404 shells get all the right environment variable definitions:
1407 GUIX_PROFILE="$HOME/.guix-profile" \
1408 source "$HOME/.guix-profile/etc/profile"
1411 In a multi-user setup, user profiles are stored in a place registered as
1412 a @dfn{garbage-collector root}, which @file{$HOME/.guix-profile} points
1413 to (@pxref{Invoking guix gc}). That directory is normally
1414 @code{@var{localstatedir}/profiles/per-user/@var{user}}, where
1415 @var{localstatedir} is the value passed to @code{configure} as
1416 @code{--localstatedir}, and @var{user} is the user name. The
1417 @file{per-user} directory is created when @command{guix-daemon} is
1418 started, and the @var{user} sub-directory is created by @command{guix
1421 The @var{options} can be among the following:
1425 @item --install=@var{package} @dots{}
1426 @itemx -i @var{package} @dots{}
1427 Install the specified @var{package}s.
1429 Each @var{package} may specify either a simple package name, such as
1430 @code{guile}, or a package name followed by an at-sign and version number,
1431 such as @code{guile@@1.8.8} or simply @code{guile@@1.8} (in the latter
1432 case, the newest version prefixed by @code{1.8} is selected.)
1434 If no version number is specified, the
1435 newest available version will be selected. In addition, @var{package}
1436 may contain a colon, followed by the name of one of the outputs of the
1437 package, as in @code{gcc:doc} or @code{binutils@@2.22:lib}
1438 (@pxref{Packages with Multiple Outputs}). Packages with a corresponding
1439 name (and optionally version) are searched for among the GNU
1440 distribution modules (@pxref{Package Modules}).
1442 @cindex propagated inputs
1443 Sometimes packages have @dfn{propagated inputs}: these are dependencies
1444 that automatically get installed along with the required package
1445 (@pxref{package-propagated-inputs, @code{propagated-inputs} in
1446 @code{package} objects}, for information about propagated inputs in
1447 package definitions).
1449 @anchor{package-cmd-propagated-inputs}
1450 An example is the GNU MPC library: its C header files refer to those of
1451 the GNU MPFR library, which in turn refer to those of the GMP library.
1452 Thus, when installing MPC, the MPFR and GMP libraries also get installed
1453 in the profile; removing MPC also removes MPFR and GMP---unless they had
1454 also been explicitly installed by the user.
1456 Besides, packages sometimes rely on the definition of environment
1457 variables for their search paths (see explanation of
1458 @code{--search-paths} below). Any missing or possibly incorrect
1459 environment variable definitions are reported here.
1461 @item --install-from-expression=@var{exp}
1463 Install the package @var{exp} evaluates to.
1465 @var{exp} must be a Scheme expression that evaluates to a
1466 @code{<package>} object. This option is notably useful to disambiguate
1467 between same-named variants of a package, with expressions such as
1468 @code{(@@ (gnu packages base) guile-final)}.
1470 Note that this option installs the first output of the specified
1471 package, which may be insufficient when needing a specific output of a
1472 multiple-output package.
1474 @item --install-from-file=@var{file}
1475 @itemx -f @var{file}
1476 Install the package that the code within @var{file} evaluates to.
1478 As an example, @var{file} might contain a definition like this
1479 (@pxref{Defining Packages}):
1482 @verbatiminclude package-hello.scm
1485 Developers may find it useful to include such a @file{guix.scm} file
1486 in the root of their project source tree that can be used to test
1487 development snapshots and create reproducible development environments
1488 (@pxref{Invoking guix environment}).
1490 @item --remove=@var{package} @dots{}
1491 @itemx -r @var{package} @dots{}
1492 Remove the specified @var{package}s.
1494 As for @code{--install}, each @var{package} may specify a version number
1495 and/or output name in addition to the package name. For instance,
1496 @code{-r glibc:debug} would remove the @code{debug} output of
1499 @item --upgrade[=@var{regexp} @dots{}]
1500 @itemx -u [@var{regexp} @dots{}]
1501 Upgrade all the installed packages. If one or more @var{regexp}s are
1502 specified, upgrade only installed packages whose name matches a
1503 @var{regexp}. Also see the @code{--do-not-upgrade} option below.
1505 Note that this upgrades package to the latest version of packages found
1506 in the distribution currently installed. To update your distribution,
1507 you should regularly run @command{guix pull} (@pxref{Invoking guix
1510 @item --do-not-upgrade[=@var{regexp} @dots{}]
1511 When used together with the @code{--upgrade} option, do @emph{not}
1512 upgrade any packages whose name matches a @var{regexp}. For example, to
1513 upgrade all packages in the current profile except those containing the
1514 substring ``emacs'':
1517 $ guix package --upgrade . --do-not-upgrade emacs
1520 @item @anchor{profile-manifest}--manifest=@var{file}
1521 @itemx -m @var{file}
1522 @cindex profile declaration
1523 @cindex profile manifest
1524 Create a new generation of the profile from the manifest object
1525 returned by the Scheme code in @var{file}.
1527 This allows you to @emph{declare} the profile's contents rather than
1528 constructing it through a sequence of @code{--install} and similar
1529 commands. The advantage is that @var{file} can be put under version
1530 control, copied to different machines to reproduce the same profile, and
1533 @c FIXME: Add reference to (guix profile) documentation when available.
1534 @var{file} must return a @dfn{manifest} object, which is roughly a list
1537 @findex packages->manifest
1539 (use-package-modules guile emacs)
1544 ;; Use a specific package output.
1545 (list guile-2.0 "debug")))
1549 Roll back to the previous @dfn{generation} of the profile---i.e., undo
1550 the last transaction.
1552 When combined with options such as @code{--install}, roll back occurs
1553 before any other actions.
1555 When rolling back from the first generation that actually contains
1556 installed packages, the profile is made to point to the @dfn{zeroth
1557 generation}, which contains no files apart from its own metadata.
1559 After having rolled back, installing, removing, or upgrading packages
1560 overwrites previous future generations. Thus, the history of the
1561 generations in a profile is always linear.
1563 @item --switch-generation=@var{pattern}
1564 @itemx -S @var{pattern}
1565 Switch to a particular generation defined by @var{pattern}.
1567 @var{pattern} may be either a generation number or a number prefixed
1568 with ``+'' or ``-''. The latter means: move forward/backward by a
1569 specified number of generations. For example, if you want to return to
1570 the latest generation after @code{--roll-back}, use
1571 @code{--switch-generation=+1}.
1573 The difference between @code{--roll-back} and
1574 @code{--switch-generation=-1} is that @code{--switch-generation} will
1575 not make a zeroth generation, so if a specified generation does not
1576 exist, the current generation will not be changed.
1578 @item --search-paths[=@var{kind}]
1579 @cindex search paths
1580 Report environment variable definitions, in Bash syntax, that may be
1581 needed in order to use the set of installed packages. These environment
1582 variables are used to specify @dfn{search paths} for files used by some
1583 of the installed packages.
1585 For example, GCC needs the @code{CPATH} and @code{LIBRARY_PATH}
1586 environment variables to be defined so it can look for headers and
1587 libraries in the user's profile (@pxref{Environment Variables,,, gcc,
1588 Using the GNU Compiler Collection (GCC)}). If GCC and, say, the C
1589 library are installed in the profile, then @code{--search-paths} will
1590 suggest setting these variables to @code{@var{profile}/include} and
1591 @code{@var{profile}/lib}, respectively.
1593 The typical use case is to define these environment variables in the
1597 $ eval `guix package --search-paths`
1600 @var{kind} may be one of @code{exact}, @code{prefix}, or @code{suffix},
1601 meaning that the returned environment variable definitions will either
1602 be exact settings, or prefixes or suffixes of the current value of these
1603 variables. When omitted, @var{kind} defaults to @code{exact}.
1605 This option can also be used to compute the @emph{combined} search paths
1606 of several profiles. Consider this example:
1609 $ guix package -p foo -i guile
1610 $ guix package -p bar -i guile-json
1611 $ guix package -p foo -p bar --search-paths
1614 The last command above reports about the @code{GUILE_LOAD_PATH}
1615 variable, even though, taken individually, neither @file{foo} nor
1616 @file{bar} would lead to that recommendation.
1619 @item --profile=@var{profile}
1620 @itemx -p @var{profile}
1621 Use @var{profile} instead of the user's default profile.
1624 Produce verbose output. In particular, emit the build log of the
1625 environment on the standard error port.
1628 Use the bootstrap Guile to build the profile. This option is only
1629 useful to distribution developers.
1633 In addition to these actions, @command{guix package} supports the
1634 following options to query the current state of a profile, or the
1635 availability of packages:
1639 @item --search=@var{regexp}
1640 @itemx -s @var{regexp}
1641 @cindex searching for packages
1642 List the available packages whose name, synopsis, or description matches
1643 @var{regexp}. Print all the metadata of matching packages in
1644 @code{recutils} format (@pxref{Top, GNU recutils databases,, recutils,
1645 GNU recutils manual}).
1647 This allows specific fields to be extracted using the @command{recsel}
1648 command, for instance:
1651 $ guix package -s malloc | recsel -p name,version
1659 Similarly, to show the name of all the packages available under the
1660 terms of the GNU@tie{}LGPL version 3:
1663 $ guix package -s "" | recsel -p name -e 'license ~ "LGPL 3"'
1670 It is also possible to refine search results using several @code{-s}
1671 flags. For example, the following command returns a list of board
1675 $ guix package -s '\<board\>' -s game | recsel -p name
1680 If we were to omit @code{-s game}, we would also get software packages
1681 that deal with printed circuit boards; removing the angle brackets
1682 around @code{board} would further add packages that have to do with
1685 And now for a more elaborate example. The following command searches
1686 for cryptographic libraries, filters out Haskell, Perl, Python, and Ruby
1687 libraries, and prints the name and synopsis of the matching packages:
1690 $ guix package -s crypto -s library | \
1691 recsel -e '! (name ~ "^(ghc|perl|python|ruby)")' -p name,synopsis
1695 @xref{Selection Expressions,,, recutils, GNU recutils manual}, for more
1696 information on @dfn{selection expressions} for @code{recsel -e}.
1698 @item --show=@var{package}
1699 Show details about @var{package}, taken from the list of available packages, in
1700 @code{recutils} format (@pxref{Top, GNU recutils databases,, recutils, GNU
1704 $ guix package --show=python | recsel -p name,version
1712 You may also specify the full name of a package to only get details about a
1713 specific version of it:
1715 $ guix package --show=python-3.3.5 | recsel -p name,version
1722 @item --list-installed[=@var{regexp}]
1723 @itemx -I [@var{regexp}]
1724 List the currently installed packages in the specified profile, with the
1725 most recently installed packages shown last. When @var{regexp} is
1726 specified, list only installed packages whose name matches @var{regexp}.
1728 For each installed package, print the following items, separated by
1729 tabs: the package name, its version string, the part of the package that
1730 is installed (for instance, @code{out} for the default output,
1731 @code{include} for its headers, etc.), and the path of this package in
1734 @item --list-available[=@var{regexp}]
1735 @itemx -A [@var{regexp}]
1736 List packages currently available in the distribution for this system
1737 (@pxref{GNU Distribution}). When @var{regexp} is specified, list only
1738 installed packages whose name matches @var{regexp}.
1740 For each package, print the following items separated by tabs: its name,
1741 its version string, the parts of the package (@pxref{Packages with
1742 Multiple Outputs}), and the source location of its definition.
1744 @item --list-generations[=@var{pattern}]
1745 @itemx -l [@var{pattern}]
1746 Return a list of generations along with their creation dates; for each
1747 generation, show the installed packages, with the most recently
1748 installed packages shown last. Note that the zeroth generation is never
1751 For each installed package, print the following items, separated by
1752 tabs: the name of a package, its version string, the part of the package
1753 that is installed (@pxref{Packages with Multiple Outputs}), and the
1754 location of this package in the store.
1756 When @var{pattern} is used, the command returns only matching
1757 generations. Valid patterns include:
1760 @item @emph{Integers and comma-separated integers}. Both patterns denote
1761 generation numbers. For instance, @code{--list-generations=1} returns
1764 And @code{--list-generations=1,8,2} outputs three generations in the
1765 specified order. Neither spaces nor trailing commas are allowed.
1767 @item @emph{Ranges}. @code{--list-generations=2..9} prints the
1768 specified generations and everything in between. Note that the start of
1769 a range must be smaller than its end.
1771 It is also possible to omit the endpoint. For example,
1772 @code{--list-generations=2..}, returns all generations starting from the
1775 @item @emph{Durations}. You can also get the last @emph{N}@tie{}days, weeks,
1776 or months by passing an integer along with the first letter of the
1777 duration. For example, @code{--list-generations=20d} lists generations
1778 that are up to 20 days old.
1781 @item --delete-generations[=@var{pattern}]
1782 @itemx -d [@var{pattern}]
1783 When @var{pattern} is omitted, delete all generations except the current
1786 This command accepts the same patterns as @option{--list-generations}.
1787 When @var{pattern} is specified, delete the matching generations. When
1788 @var{pattern} specifies a duration, generations @emph{older} than the
1789 specified duration match. For instance, @code{--delete-generations=1m}
1790 deletes generations that are more than one month old.
1792 If the current generation matches, it is @emph{not} deleted. Also, the
1793 zeroth generation is never deleted.
1795 Note that deleting generations prevents rolling back to them.
1796 Consequently, this command must be used with care.
1800 Finally, since @command{guix package} may actually start build
1801 processes, it supports all the common build options (@pxref{Common Build
1802 Options}). It also supports package transformation options, such as
1803 @option{--with-source} (@pxref{Package Transformation Options}).
1804 However, note that package transformations are lost when upgrading; to
1805 preserve transformations across upgrades, you should define your own
1806 package variant in a Guile module and add it to @code{GUIX_PACKAGE_PATH}
1807 (@pxref{Defining Packages}).
1811 @section Substitutes
1814 @cindex pre-built binaries
1815 Guix supports transparent source/binary deployment, which means that it
1816 can either build things locally, or download pre-built items from a
1817 server. We call these pre-built items @dfn{substitutes}---they are
1818 substitutes for local build results. In many cases, downloading a
1819 substitute is much faster than building things locally.
1821 Substitutes can be anything resulting from a derivation build
1822 (@pxref{Derivations}). Of course, in the common case, they are
1823 pre-built package binaries, but source tarballs, for instance, which
1824 also result from derivation builds, can be available as substitutes.
1826 The @code{hydra.gnu.org} server is a front-end to a build farm that
1827 builds packages from the GNU distribution continuously for some
1828 architectures, and makes them available as substitutes (@pxref{Emacs
1829 Hydra}, for information on how to query the continuous integration
1830 server). This is the
1831 default source of substitutes; it can be overridden by passing the
1832 @option{--substitute-urls} option either to @command{guix-daemon}
1833 (@pxref{daemon-substitute-urls,, @code{guix-daemon --substitute-urls}})
1834 or to client tools such as @command{guix package}
1835 (@pxref{client-substitute-urls,, client @option{--substitute-urls}
1838 Substitute URLs can be either HTTP or HTTPS@footnote{For HTTPS access,
1839 the Guile bindings of GnuTLS must be installed. @xref{Requirements}.}
1840 HTTPS is recommended because communications are encrypted; conversely,
1841 using HTTP makes all communications visible to an eavesdropper, who
1842 could use the information gathered to determine, for instance, whether
1843 your system has unpatched security vulnerabilities.
1846 @cindex digital signatures
1847 To allow Guix to download substitutes from @code{hydra.gnu.org} or a
1849 must add its public key to the access control list (ACL) of archive
1850 imports, using the @command{guix archive} command (@pxref{Invoking guix
1851 archive}). Doing so implies that you trust @code{hydra.gnu.org} to not
1852 be compromised and to serve genuine substitutes.
1854 This public key is installed along with Guix, in
1855 @code{@var{prefix}/share/guix/hydra.gnu.org.pub}, where @var{prefix} is
1856 the installation prefix of Guix. If you installed Guix from source,
1857 make sure you checked the GPG signature of
1858 @file{guix-@value{VERSION}.tar.gz}, which contains this public key file.
1859 Then, you can run something like this:
1862 # guix archive --authorize < hydra.gnu.org.pub
1865 Once this is in place, the output of a command like @code{guix build}
1866 should change from something like:
1869 $ guix build emacs --dry-run
1870 The following derivations would be built:
1871 /gnu/store/yr7bnx8xwcayd6j95r2clmkdl1qh688w-emacs-24.3.drv
1872 /gnu/store/x8qsh1hlhgjx6cwsjyvybnfv2i37z23w-dbus-1.6.4.tar.gz.drv
1873 /gnu/store/1ixwp12fl950d15h2cj11c73733jay0z-alsa-lib-1.0.27.1.tar.bz2.drv
1874 /gnu/store/nlma1pw0p603fpfiqy7kn4zm105r5dmw-util-linux-2.21.drv
1882 $ guix build emacs --dry-run
1883 The following files would be downloaded:
1884 /gnu/store/pk3n22lbq6ydamyymqkkz7i69wiwjiwi-emacs-24.3
1885 /gnu/store/2ygn4ncnhrpr61rssa6z0d9x22si0va3-libjpeg-8d
1886 /gnu/store/71yz6lgx4dazma9dwn2mcjxaah9w77jq-cairo-1.12.16
1887 /gnu/store/7zdhgp0n1518lvfn8mb96sxqfmvqrl7v-libxrender-0.9.7
1892 This indicates that substitutes from @code{hydra.gnu.org} are usable and
1893 will be downloaded, when possible, for future builds.
1895 Guix ignores substitutes that are not signed, or that are not signed by
1896 one of the keys listed in the ACL. It also detects and raises an error
1897 when attempting to use a substitute that has been tampered with.
1900 Substitutes are downloaded over HTTP or HTTPS.
1901 The @code{http_proxy} environment
1902 variable can be set in the environment of @command{guix-daemon} and is
1903 honored for downloads of substitutes. Note that the value of
1904 @code{http_proxy} in the environment where @command{guix build},
1905 @command{guix package}, and other client commands are run has
1906 @emph{absolutely no effect}.
1908 When using HTTPS, the server's X.509 certificate is @emph{not} validated
1909 (in other words, the server is not authenticated), contrary to what
1910 HTTPS clients such as Web browsers usually do. This is because Guix
1911 authenticates substitute information itself, as explained above, which
1912 is what we care about (whereas X.509 certificates are about
1913 authenticating bindings between domain names and public keys.)
1915 The substitute mechanism can be disabled globally by running
1916 @code{guix-daemon} with @code{--no-substitutes} (@pxref{Invoking
1917 guix-daemon}). It can also be disabled temporarily by passing the
1918 @code{--no-substitutes} option to @command{guix package}, @command{guix
1919 build}, and other command-line tools.
1922 @unnumberedsubsec On Trusting Binaries
1924 Today, each individual's control over their own computing is at the
1925 mercy of institutions, corporations, and groups with enough power and
1926 determination to subvert the computing infrastructure and exploit its
1927 weaknesses. While using @code{hydra.gnu.org} substitutes can be
1928 convenient, we encourage users to also build on their own, or even run
1929 their own build farm, such that @code{hydra.gnu.org} is less of an
1930 interesting target. One way to help is by publishing the software you
1931 build using @command{guix publish} so that others have one more choice
1932 of server to download substitutes from (@pxref{Invoking guix publish}).
1934 Guix has the foundations to maximize build reproducibility
1935 (@pxref{Features}). In most cases, independent builds of a given
1936 package or derivation should yield bit-identical results. Thus, through
1937 a diverse set of independent package builds, we can strengthen the
1938 integrity of our systems. The @command{guix challenge} command aims to
1939 help users assess substitute servers, and to assist developers in
1940 finding out about non-deterministic package builds (@pxref{Invoking guix
1941 challenge}). Similarly, the @option{--check} option of @command{guix
1942 build} allows users to check whether previously-installed substitutes
1943 are genuine by rebuilding them locally (@pxref{build-check,
1944 @command{guix build --check}}).
1946 In the future, we want Guix to have support to publish and retrieve
1947 binaries to/from other users, in a peer-to-peer fashion. If you would
1948 like to discuss this project, join us on @email{guix-devel@@gnu.org}.
1951 @node Packages with Multiple Outputs
1952 @section Packages with Multiple Outputs
1954 @cindex multiple-output packages
1955 @cindex package outputs
1957 Often, packages defined in Guix have a single @dfn{output}---i.e., the
1958 source package leads to exactly one directory in the store. When running
1959 @command{guix package -i glibc}, one installs the default output of the
1960 GNU libc package; the default output is called @code{out}, but its name
1961 can be omitted as shown in this command. In this particular case, the
1962 default output of @code{glibc} contains all the C header files, shared
1963 libraries, static libraries, Info documentation, and other supporting
1966 Sometimes it is more appropriate to separate the various types of files
1967 produced from a single source package into separate outputs. For
1968 instance, the GLib C library (used by GTK+ and related packages)
1969 installs more than 20 MiB of reference documentation as HTML pages.
1970 To save space for users who do not need it, the documentation goes to a
1971 separate output, called @code{doc}. To install the main GLib output,
1972 which contains everything but the documentation, one would run:
1975 guix package -i glib
1978 The command to install its documentation is:
1981 guix package -i glib:doc
1984 Some packages install programs with different ``dependency footprints''.
1985 For instance, the WordNet package installs both command-line tools and
1986 graphical user interfaces (GUIs). The former depend solely on the C
1987 library, whereas the latter depend on Tcl/Tk and the underlying X
1988 libraries. In this case, we leave the command-line tools in the default
1989 output, whereas the GUIs are in a separate output. This allows users
1990 who do not need the GUIs to save space. The @command{guix size} command
1991 can help find out about such situations (@pxref{Invoking guix size}).
1992 @command{guix graph} can also be helpful (@pxref{Invoking guix graph}).
1994 There are several such multiple-output packages in the GNU distribution.
1995 Other conventional output names include @code{lib} for libraries and
1996 possibly header files, @code{bin} for stand-alone programs, and
1997 @code{debug} for debugging information (@pxref{Installing Debugging
1998 Files}). The outputs of a packages are listed in the third column of
1999 the output of @command{guix package --list-available} (@pxref{Invoking
2003 @node Invoking guix gc
2004 @section Invoking @command{guix gc}
2006 @cindex garbage collector
2007 Packages that are installed, but not used, may be @dfn{garbage-collected}.
2008 The @command{guix gc} command allows users to explicitly run the garbage
2009 collector to reclaim space from the @file{/gnu/store} directory. It is
2010 the @emph{only} way to remove files from @file{/gnu/store}---removing
2011 files or directories manually may break it beyond repair!
2013 The garbage collector has a set of known @dfn{roots}: any file under
2014 @file{/gnu/store} reachable from a root is considered @dfn{live} and
2015 cannot be deleted; any other file is considered @dfn{dead} and may be
2016 deleted. The set of garbage collector roots includes default user
2017 profiles, and may be augmented with @command{guix build --root}, for
2018 example (@pxref{Invoking guix build}).
2020 Prior to running @code{guix gc --collect-garbage} to make space, it is
2021 often useful to remove old generations from user profiles; that way, old
2022 package builds referenced by those generations can be reclaimed. This
2023 is achieved by running @code{guix package --delete-generations}
2024 (@pxref{Invoking guix package}).
2026 The @command{guix gc} command has three modes of operation: it can be
2027 used to garbage-collect any dead files (the default), to delete specific
2028 files (the @code{--delete} option), to print garbage-collector
2029 information, or for more advanced queries. The garbage collection
2030 options are as follows:
2033 @item --collect-garbage[=@var{min}]
2034 @itemx -C [@var{min}]
2035 Collect garbage---i.e., unreachable @file{/gnu/store} files and
2036 sub-directories. This is the default operation when no option is
2039 When @var{min} is given, stop once @var{min} bytes have been collected.
2040 @var{min} may be a number of bytes, or it may include a unit as a
2041 suffix, such as @code{MiB} for mebibytes and @code{GB} for gigabytes
2042 (@pxref{Block size, size specifications,, coreutils, GNU Coreutils}).
2044 When @var{min} is omitted, collect all the garbage.
2046 @item --free-space=@var{free}
2047 @itemx -F @var{free}
2048 Collect garbage until @var{free} space is available under
2049 @file{/gnu/store}, if possible; @var{free} denotes storage space, such
2050 as @code{500MiB}, as described above.
2052 When @var{free} or more is already available in @file{/gnu/store}, do
2053 nothing and exit immediately.
2057 Attempt to delete all the store files and directories specified as
2058 arguments. This fails if some of the files are not in the store, or if
2059 they are still live.
2061 @item --list-failures
2062 List store items corresponding to cached build failures.
2064 This prints nothing unless the daemon was started with
2065 @option{--cache-failures} (@pxref{Invoking guix-daemon,
2066 @option{--cache-failures}}).
2068 @item --clear-failures
2069 Remove the specified store items from the failed-build cache.
2071 Again, this option only makes sense when the daemon is started with
2072 @option{--cache-failures}. Otherwise, it does nothing.
2075 Show the list of dead files and directories still present in the
2076 store---i.e., files and directories no longer reachable from any root.
2079 Show the list of live store files and directories.
2083 In addition, the references among existing store files can be queried:
2089 List the references (respectively, the referrers) of store files given
2095 List the requisites of the store files passed as arguments. Requisites
2096 include the store files themselves, their references, and the references
2097 of these, recursively. In other words, the returned list is the
2098 @dfn{transitive closure} of the store files.
2100 @xref{Invoking guix size}, for a tool to profile the size of the closure
2101 of an element. @xref{Invoking guix graph}, for a tool to visualize
2102 the graph of references.
2106 Lastly, the following options allow you to check the integrity of the
2107 store and to control disk usage.
2111 @item --verify[=@var{options}]
2112 @cindex integrity, of the store
2113 @cindex integrity checking
2114 Verify the integrity of the store.
2116 By default, make sure that all the store items marked as valid in the
2117 database of the daemon actually exist in @file{/gnu/store}.
2119 When provided, @var{options} must be a comma-separated list containing one
2120 or more of @code{contents} and @code{repair}.
2122 When passing @option{--verify=contents}, the daemon computse the
2123 content hash of each store item and compares it against its hash in the
2124 database. Hash mismatches are reported as data corruptions. Because it
2125 traverses @emph{all the files in the store}, this command can take a
2126 long time, especially on systems with a slow disk drive.
2128 @cindex repairing the store
2129 Using @option{--verify=repair} or @option{--verify=contents,repair}
2130 causes the daemon to try to repair corrupt store items by fetching
2131 substitutes for them (@pxref{Substitutes}). Because repairing is not
2132 atomic, and thus potentially dangerous, it is available only to the
2133 system administrator.
2136 @cindex deduplication
2137 Optimize the store by hard-linking identical files---this is
2138 @dfn{deduplication}.
2140 The daemon performs deduplication after each successful build or archive
2141 import, unless it was started with @code{--disable-deduplication}
2142 (@pxref{Invoking guix-daemon, @code{--disable-deduplication}}). Thus,
2143 this option is primarily useful when the daemon was running with
2144 @code{--disable-deduplication}.
2148 @node Invoking guix pull
2149 @section Invoking @command{guix pull}
2151 Packages are installed or upgraded to the latest version available in
2152 the distribution currently available on your local machine. To update
2153 that distribution, along with the Guix tools, you must run @command{guix
2154 pull}: the command downloads the latest Guix source code and package
2155 descriptions, and deploys it.
2157 On completion, @command{guix package} will use packages and package
2158 versions from this just-retrieved copy of Guix. Not only that, but all
2159 the Guix commands and Scheme modules will also be taken from that latest
2160 version. New @command{guix} sub-commands added by the update also
2163 Any user can update their Guix copy using @command{guix pull}, and the
2164 effect is limited to the user who run @command{guix pull}. For
2165 instance, when user @code{root} runs @command{guix pull}, this has no
2166 effect on the version of Guix that user @code{alice} sees, and vice
2167 versa@footnote{Under the hood, @command{guix pull} updates the
2168 @file{~/.config/guix/latest} symbolic link to point to the latest Guix,
2169 and the @command{guix} command loads code from there.}.
2171 The @command{guix pull} command is usually invoked with no arguments,
2172 but it supports the following options:
2176 Produce verbose output, writing build logs to the standard error output.
2178 @item --url=@var{url}
2179 Download the source tarball of Guix from @var{url}.
2181 By default, the tarball is taken from its canonical address at
2182 @code{gnu.org}, for the stable branch of Guix.
2185 Use the bootstrap Guile to build the latest Guix. This option is only
2186 useful to Guix developers.
2190 @node Invoking guix archive
2191 @section Invoking @command{guix archive}
2193 The @command{guix archive} command allows users to @dfn{export} files
2194 from the store into a single archive, and to later @dfn{import} them.
2195 In particular, it allows store files to be transferred from one machine
2196 to the store on another machine.
2198 To export store files as an archive to standard output, run:
2201 guix archive --export @var{options} @var{specifications}...
2204 @var{specifications} may be either store file names or package
2205 specifications, as for @command{guix package} (@pxref{Invoking guix
2206 package}). For instance, the following command creates an archive
2207 containing the @code{gui} output of the @code{git} package and the main
2208 output of @code{emacs}:
2211 guix archive --export git:gui /gnu/store/...-emacs-24.3 > great.nar
2214 If the specified packages are not built yet, @command{guix archive}
2215 automatically builds them. The build process may be controlled with the
2216 common build options (@pxref{Common Build Options}).
2218 To transfer the @code{emacs} package to a machine connected over SSH,
2222 guix archive --export -r emacs | ssh the-machine guix archive --import
2226 Similarly, a complete user profile may be transferred from one machine
2227 to another like this:
2230 guix archive --export -r $(readlink -f ~/.guix-profile) | \
2231 ssh the-machine guix-archive --import
2235 However, note that, in both examples, all of @code{emacs} and the
2236 profile as well as all of their dependencies are transferred (due to
2237 @code{-r}), regardless of what is already available in the store on the
2238 target machine. The @code{--missing} option can help figure out which
2239 items are missing from the target store.
2241 Archives are stored in the ``Nix archive'' or ``Nar'' format, which is
2242 comparable in spirit to `tar', but with a few noteworthy differences
2243 that make it more appropriate for our purposes. First, rather than
2244 recording all Unix metadata for each file, the Nar format only mentions
2245 the file type (regular, directory, or symbolic link); Unix permissions
2246 and owner/group are dismissed. Second, the order in which directory
2247 entries are stored always follows the order of file names according to
2248 the C locale collation order. This makes archive production fully
2251 When exporting, the daemon digitally signs the contents of the archive,
2252 and that digital signature is appended. When importing, the daemon
2253 verifies the signature and rejects the import in case of an invalid
2254 signature or if the signing key is not authorized.
2255 @c FIXME: Add xref to daemon doc about signatures.
2257 The main options are:
2261 Export the specified store files or packages (see below.) Write the
2262 resulting archive to the standard output.
2264 Dependencies are @emph{not} included in the output, unless
2265 @code{--recursive} is passed.
2269 When combined with @code{--export}, this instructs @command{guix
2270 archive} to include dependencies of the given items in the archive.
2271 Thus, the resulting archive is self-contained: it contains the closure
2272 of the exported store items.
2275 Read an archive from the standard input, and import the files listed
2276 therein into the store. Abort if the archive has an invalid digital
2277 signature, or if it is signed by a public key not among the authorized
2278 keys (see @code{--authorize} below.)
2281 Read a list of store file names from the standard input, one per line,
2282 and write on the standard output the subset of these files missing from
2285 @item --generate-key[=@var{parameters}]
2286 @cindex signing, archives
2287 Generate a new key pair for the daemon. This is a prerequisite before
2288 archives can be exported with @code{--export}. Note that this operation
2289 usually takes time, because it needs to gather enough entropy to
2290 generate the key pair.
2292 The generated key pair is typically stored under @file{/etc/guix}, in
2293 @file{signing-key.pub} (public key) and @file{signing-key.sec} (private
2294 key, which must be kept secret.) When @var{parameters} is omitted,
2295 an ECDSA key using the Ed25519 curve is generated, or, for Libgcrypt
2296 versions before 1.6.0, it is a 4096-bit RSA key.
2297 Alternatively, @var{parameters} can specify
2298 @code{genkey} parameters suitable for Libgcrypt (@pxref{General
2299 public-key related Functions, @code{gcry_pk_genkey},, gcrypt, The
2300 Libgcrypt Reference Manual}).
2303 @cindex authorizing, archives
2304 Authorize imports signed by the public key passed on standard input.
2305 The public key must be in ``s-expression advanced format''---i.e., the
2306 same format as the @file{signing-key.pub} file.
2308 The list of authorized keys is kept in the human-editable file
2309 @file{/etc/guix/acl}. The file contains
2310 @url{http://people.csail.mit.edu/rivest/Sexp.txt, ``advanced-format
2311 s-expressions''} and is structured as an access-control list in the
2312 @url{http://theworld.com/~cme/spki.txt, Simple Public-Key Infrastructure
2315 @item --extract=@var{directory}
2316 @itemx -x @var{directory}
2317 Read a single-item archive as served by substitute servers
2318 (@pxref{Substitutes}) and extract it to @var{directory}. This is a
2319 low-level operation needed in only very narrow use cases; see below.
2321 For example, the following command extracts the substitute for Emacs
2322 served by @code{hydra.gnu.org} to @file{/tmp/emacs}:
2326 https://hydra.gnu.org/nar/@dots{}-emacs-24.5 \
2327 | bunzip2 | guix archive -x /tmp/emacs
2330 Single-item archives are different from multiple-item archives produced
2331 by @command{guix archive --export}; they contain a single store item,
2332 and they do @emph{not} embed a signature. Thus this operation does
2333 @emph{no} signature verification and its output should be considered
2336 The primary purpose of this operation is to facilitate inspection of
2337 archive contents coming from possibly untrusted substitute servers.
2341 @c *********************************************************************
2344 @c *********************************************************************
2345 @node Programming Interface
2346 @chapter Programming Interface
2348 GNU Guix provides several Scheme programming interfaces (APIs) to
2349 define, build, and query packages. The first interface allows users to
2350 write high-level package definitions. These definitions refer to
2351 familiar packaging concepts, such as the name and version of a package,
2352 its build system, and its dependencies. These definitions can then be
2353 turned into concrete build actions.
2355 Build actions are performed by the Guix daemon, on behalf of users. In a
2356 standard setup, the daemon has write access to the store---the
2357 @file{/gnu/store} directory---whereas users do not. The recommended
2358 setup also has the daemon perform builds in chroots, under a specific
2359 build users, to minimize interference with the rest of the system.
2362 Lower-level APIs are available to interact with the daemon and the
2363 store. To instruct the daemon to perform a build action, users actually
2364 provide it with a @dfn{derivation}. A derivation is a low-level
2365 representation of the build actions to be taken, and the environment in
2366 which they should occur---derivations are to package definitions what
2367 assembly is to C programs. The term ``derivation'' comes from the fact
2368 that build results @emph{derive} from them.
2370 This chapter describes all these APIs in turn, starting from high-level
2371 package definitions.
2374 * Defining Packages:: Defining new packages.
2375 * Build Systems:: Specifying how packages are built.
2376 * The Store:: Manipulating the package store.
2377 * Derivations:: Low-level interface to package derivations.
2378 * The Store Monad:: Purely functional interface to the store.
2379 * G-Expressions:: Manipulating build expressions.
2382 @node Defining Packages
2383 @section Defining Packages
2385 The high-level interface to package definitions is implemented in the
2386 @code{(guix packages)} and @code{(guix build-system)} modules. As an
2387 example, the package definition, or @dfn{recipe}, for the GNU Hello
2388 package looks like this:
2391 (define-module (gnu packages hello)
2392 #:use-module (guix packages)
2393 #:use-module (guix download)
2394 #:use-module (guix build-system gnu)
2395 #:use-module (guix licenses)
2396 #:use-module (gnu packages gawk))
2398 (define-public hello
2404 (uri (string-append "mirror://gnu/hello/hello-" version
2408 "0ssi1wpaf7plaswqqjwigppsg5fyh99vdlb9kzl7c9lng89ndq1i"))))
2409 (build-system gnu-build-system)
2410 (arguments '(#:configure-flags '("--enable-silent-rules")))
2411 (inputs `(("gawk" ,gawk)))
2412 (synopsis "Hello, GNU world: An example GNU package")
2413 (description "Guess what GNU Hello prints!")
2414 (home-page "http://www.gnu.org/software/hello/")
2419 Without being a Scheme expert, the reader may have guessed the meaning
2420 of the various fields here. This expression binds the variable
2421 @code{hello} to a @code{<package>} object, which is essentially a record
2422 (@pxref{SRFI-9, Scheme records,, guile, GNU Guile Reference Manual}).
2423 This package object can be inspected using procedures found in the
2424 @code{(guix packages)} module; for instance, @code{(package-name hello)}
2425 returns---surprise!---@code{"hello"}.
2427 With luck, you may be able to import part or all of the definition of
2428 the package you are interested in from another repository, using the
2429 @code{guix import} command (@pxref{Invoking guix import}).
2431 In the example above, @var{hello} is defined in a module of its own,
2432 @code{(gnu packages hello)}. Technically, this is not strictly
2433 necessary, but it is convenient to do so: all the packages defined in
2434 modules under @code{(gnu packages @dots{})} are automatically known to
2435 the command-line tools (@pxref{Package Modules}).
2437 There are a few points worth noting in the above package definition:
2441 The @code{source} field of the package is an @code{<origin>} object
2442 (@pxref{origin Reference}, for the complete reference).
2443 Here, the @code{url-fetch} method from @code{(guix download)} is used,
2444 meaning that the source is a file to be downloaded over FTP or HTTP.
2446 The @code{mirror://gnu} prefix instructs @code{url-fetch} to use one of
2447 the GNU mirrors defined in @code{(guix download)}.
2449 The @code{sha256} field specifies the expected SHA256 hash of the file
2450 being downloaded. It is mandatory, and allows Guix to check the
2451 integrity of the file. The @code{(base32 @dots{})} form introduces the
2452 base32 representation of the hash. You can obtain this information with
2453 @code{guix download} (@pxref{Invoking guix download}) and @code{guix
2454 hash} (@pxref{Invoking guix hash}).
2457 When needed, the @code{origin} form can also have a @code{patches} field
2458 listing patches to be applied, and a @code{snippet} field giving a
2459 Scheme expression to modify the source code.
2462 @cindex GNU Build System
2463 The @code{build-system} field specifies the procedure to build the
2464 package (@pxref{Build Systems}). Here, @var{gnu-build-system}
2465 represents the familiar GNU Build System, where packages may be
2466 configured, built, and installed with the usual @code{./configure &&
2467 make && make check && make install} command sequence.
2470 The @code{arguments} field specifies options for the build system
2471 (@pxref{Build Systems}). Here it is interpreted by
2472 @var{gnu-build-system} as a request run @file{configure} with the
2473 @code{--enable-silent-rules} flag.
2479 What about these quote (@code{'}) characters? They are Scheme syntax to
2480 introduce a literal list; @code{'} is synonymous with @code{quote}.
2481 @xref{Expression Syntax, quoting,, guile, GNU Guile Reference Manual},
2482 for details. Here the value of the @code{arguments} field is a list of
2483 arguments passed to the build system down the road, as with @code{apply}
2484 (@pxref{Fly Evaluation, @code{apply},, guile, GNU Guile Reference
2487 The hash-colon (@code{#:}) sequence defines a Scheme @dfn{keyword}
2488 (@pxref{Keywords,,, guile, GNU Guile Reference Manual}), and
2489 @code{#:configure-flags} is a keyword used to pass a keyword argument
2490 to the build system (@pxref{Coding With Keywords,,, guile, GNU Guile
2494 The @code{inputs} field specifies inputs to the build process---i.e.,
2495 build-time or run-time dependencies of the package. Here, we define an
2496 input called @code{"gawk"} whose value is that of the @var{gawk}
2497 variable; @var{gawk} is itself bound to a @code{<package>} object.
2499 @cindex backquote (quasiquote)
2502 @cindex comma (unquote)
2506 @findex unquote-splicing
2507 Again, @code{`} (a backquote, synonymous with @code{quasiquote}) allows
2508 us to introduce a literal list in the @code{inputs} field, while
2509 @code{,} (a comma, synonymous with @code{unquote}) allows us to insert a
2510 value in that list (@pxref{Expression Syntax, unquote,, guile, GNU Guile
2513 Note that GCC, Coreutils, Bash, and other essential tools do not need to
2514 be specified as inputs here. Instead, @var{gnu-build-system} takes care
2515 of ensuring that they are present (@pxref{Build Systems}).
2517 However, any other dependencies need to be specified in the
2518 @code{inputs} field. Any dependency not specified here will simply be
2519 unavailable to the build process, possibly leading to a build failure.
2522 @xref{package Reference}, for a full description of possible fields.
2524 Once a package definition is in place, the
2525 package may actually be built using the @code{guix build} command-line
2526 tool (@pxref{Invoking guix build}). You can easily jump back to the
2527 package definition using the @command{guix edit} command
2528 (@pxref{Invoking guix edit}).
2529 @xref{Packaging Guidelines}, for
2530 more information on how to test package definitions, and
2531 @ref{Invoking guix lint}, for information on how to check a definition
2532 for style conformance.
2534 Finally, updating the package definition to a new upstream version
2535 can be partly automated by the @command{guix refresh} command
2536 (@pxref{Invoking guix refresh}).
2538 Behind the scenes, a derivation corresponding to the @code{<package>}
2539 object is first computed by the @code{package-derivation} procedure.
2540 That derivation is stored in a @code{.drv} file under @file{/gnu/store}.
2541 The build actions it prescribes may then be realized by using the
2542 @code{build-derivations} procedure (@pxref{The Store}).
2544 @deffn {Scheme Procedure} package-derivation @var{store} @var{package} [@var{system}]
2545 Return the @code{<derivation>} object of @var{package} for @var{system}
2546 (@pxref{Derivations}).
2548 @var{package} must be a valid @code{<package>} object, and @var{system}
2549 must be a string denoting the target system type---e.g.,
2550 @code{"x86_64-linux"} for an x86_64 Linux-based GNU system. @var{store}
2551 must be a connection to the daemon, which operates on the store
2552 (@pxref{The Store}).
2556 @cindex cross-compilation
2557 Similarly, it is possible to compute a derivation that cross-builds a
2558 package for some other system:
2560 @deffn {Scheme Procedure} package-cross-derivation @var{store} @
2561 @var{package} @var{target} [@var{system}]
2562 Return the @code{<derivation>} object of @var{package} cross-built from
2563 @var{system} to @var{target}.
2565 @var{target} must be a valid GNU triplet denoting the target hardware
2566 and operating system, such as @code{"mips64el-linux-gnu"}
2567 (@pxref{Configuration Names, GNU configuration triplets,, configure, GNU
2568 Configure and Build System}).
2572 * package Reference :: The package data type.
2573 * origin Reference:: The origin data type.
2577 @node package Reference
2578 @subsection @code{package} Reference
2580 This section summarizes all the options available in @code{package}
2581 declarations (@pxref{Defining Packages}).
2583 @deftp {Data Type} package
2584 This is the data type representing a package recipe.
2588 The name of the package, as a string.
2590 @item @code{version}
2591 The version of the package, as a string.
2594 An object telling how the source code for the package should be
2595 acquired. Most of the time, this is an @code{origin} object, which
2596 denotes a file fetched from the Internet (@pxref{origin Reference}). It
2597 can also be any other ``file-like'' object such as a @code{local-file},
2598 which denotes a file from the local file system (@pxref{G-Expressions,
2599 @code{local-file}}).
2601 @item @code{build-system}
2602 The build system that should be used to build the package (@pxref{Build
2605 @item @code{arguments} (default: @code{'()})
2606 The arguments that should be passed to the build system. This is a
2607 list, typically containing sequential keyword-value pairs.
2609 @item @code{inputs} (default: @code{'()})
2610 @itemx @code{native-inputs} (default: @code{'()})
2611 @itemx @code{propagated-inputs} (default: @code{'()})
2612 @cindex inputs, of packages
2613 These fields list dependencies of the package. Each one is a list of
2614 tuples, where each tuple has a label for the input (a string) as its
2615 first element, a package, origin, or derivation as its second element,
2616 and optionally the name of the output thereof that should be used, which
2617 defaults to @code{"out"} (@pxref{Packages with Multiple Outputs}, for
2618 more on package outputs). For example, the list below specifies three
2622 `(("libffi" ,libffi)
2623 ("libunistring" ,libunistring)
2624 ("glib:bin" ,glib "bin")) ;the "bin" output of Glib
2627 @cindex cross compilation, package dependencies
2628 The distinction between @code{native-inputs} and @code{inputs} is
2629 necessary when considering cross-compilation. When cross-compiling,
2630 dependencies listed in @code{inputs} are built for the @emph{target}
2631 architecture; conversely, dependencies listed in @code{native-inputs}
2632 are built for the architecture of the @emph{build} machine.
2634 @code{native-inputs} is typically used to list tools needed at
2635 build time, but not at run time, such as Autoconf, Automake, pkg-config,
2636 Gettext, or Bison. @command{guix lint} can report likely mistakes in
2637 this area (@pxref{Invoking guix lint}).
2639 @anchor{package-propagated-inputs}
2640 Lastly, @code{propagated-inputs} is similar to @code{inputs}, but the
2641 specified packages will be automatically installed alongside the package
2642 they belong to (@pxref{package-cmd-propagated-inputs, @command{guix
2643 package}}, for information on how @command{guix package} deals with
2646 For example this is necessary when a C/C++ library needs headers of
2647 another library to compile, or when a pkg-config file refers to another
2648 one @i{via} its @code{Requires} field.
2650 Another example where @code{propagated-inputs} is useful is for languages
2651 that lack a facility to record the run-time search path akin to the
2652 @code{RUNPATH} of ELF files; this includes Guile, Python, Perl, GHC, and
2653 more. To ensure that libraries written in those languages can find
2654 library code they depend on at run time, run-time dependencies must be
2655 listed in @code{propagated-inputs} rather than @code{inputs}.
2657 @item @code{self-native-input?} (default: @code{#f})
2658 This is a Boolean field telling whether the package should use itself as
2659 a native input when cross-compiling.
2661 @item @code{outputs} (default: @code{'("out")})
2662 The list of output names of the package. @xref{Packages with Multiple
2663 Outputs}, for typical uses of additional outputs.
2665 @item @code{native-search-paths} (default: @code{'()})
2666 @itemx @code{search-paths} (default: @code{'()})
2667 A list of @code{search-path-specification} objects describing
2668 search-path environment variables honored by the package.
2670 @item @code{replacement} (default: @code{#f})
2671 This must be either @code{#f} or a package object that will be used as a
2672 @dfn{replacement} for this package. @xref{Security Updates, grafts},
2675 @item @code{synopsis}
2676 A one-line description of the package.
2678 @item @code{description}
2679 A more elaborate description of the package.
2681 @item @code{license}
2682 The license of the package; a value from @code{(guix licenses)},
2683 or a list of such values.
2685 @item @code{home-page}
2686 The URL to the home-page of the package, as a string.
2688 @item @code{supported-systems} (default: @var{%supported-systems})
2689 The list of systems supported by the package, as strings of the form
2690 @code{architecture-kernel}, for example @code{"x86_64-linux"}.
2692 @item @code{maintainers} (default: @code{'()})
2693 The list of maintainers of the package, as @code{maintainer} objects.
2695 @item @code{location} (default: source location of the @code{package} form)
2696 The source location of the package. It is useful to override this when
2697 inheriting from another package, in which case this field is not
2698 automatically corrected.
2703 @node origin Reference
2704 @subsection @code{origin} Reference
2706 This section summarizes all the options available in @code{origin}
2707 declarations (@pxref{Defining Packages}).
2709 @deftp {Data Type} origin
2710 This is the data type representing a source code origin.
2714 An object containing the URI of the source. The object type depends on
2715 the @code{method} (see below). For example, when using the
2716 @var{url-fetch} method of @code{(guix download)}, the valid @code{uri}
2717 values are: a URL represented as a string, or a list thereof.
2720 A procedure that handles the URI.
2725 @item @var{url-fetch} from @code{(guix download)}
2726 download a file from the HTTP, HTTPS, or FTP URL specified in the
2730 @item @var{git-fetch} from @code{(guix git-download)}
2731 clone the Git version control repository, and check out the revision
2732 specified in the @code{uri} field as a @code{git-reference} object; a
2733 @code{git-reference} looks like this:
2737 (url "git://git.debian.org/git/pkg-shadow/shadow")
2738 (commit "v4.1.5.1"))
2743 A bytevector containing the SHA-256 hash of the source. Typically the
2744 @code{base32} form is used here to generate the bytevector from a
2747 You can obtain this information using @code{guix download}
2748 (@pxref{Invoking guix download}) or @code{guix hash} (@pxref{Invoking
2751 @item @code{file-name} (default: @code{#f})
2752 The file name under which the source code should be saved. When this is
2753 @code{#f}, a sensible default value will be used in most cases. In case
2754 the source is fetched from a URL, the file name from the URL will be
2755 used. For version control checkouts, it is recommended to provide the
2756 file name explicitly because the default is not very descriptive.
2758 @item @code{patches} (default: @code{'()})
2759 A list of file names containing patches to be applied to the source.
2761 @item @code{snippet} (default: @code{#f})
2762 A G-expression (@pxref{G-Expressions}) or S-expression that will be run
2763 in the source directory. This is a convenient way to modify the source,
2764 sometimes more convenient than a patch.
2766 @item @code{patch-flags} (default: @code{'("-p1")})
2767 A list of command-line flags that should be passed to the @code{patch}
2770 @item @code{patch-inputs} (default: @code{#f})
2771 Input packages or derivations to the patching process. When this is
2772 @code{#f}, the usual set of inputs necessary for patching are provided,
2773 such as GNU@tie{}Patch.
2775 @item @code{modules} (default: @code{'()})
2776 A list of Guile modules that should be loaded during the patching
2777 process and while running the code in the @code{snippet} field.
2779 @item @code{patch-guile} (default: @code{#f})
2780 The Guile package that should be used in the patching process. When
2781 this is @code{#f}, a sensible default is used.
2787 @section Build Systems
2789 @cindex build system
2790 Each package definition specifies a @dfn{build system} and arguments for
2791 that build system (@pxref{Defining Packages}). This @code{build-system}
2792 field represents the build procedure of the package, as well as implicit
2793 dependencies of that build procedure.
2795 Build systems are @code{<build-system>} objects. The interface to
2796 create and manipulate them is provided by the @code{(guix build-system)}
2797 module, and actual build systems are exported by specific modules.
2799 @cindex bag (low-level package representation)
2800 Under the hood, build systems first compile package objects to
2801 @dfn{bags}. A @dfn{bag} is like a package, but with less
2802 ornamentation---in other words, a bag is a lower-level representation of
2803 a package, which includes all the inputs of that package, including some
2804 that were implicitly added by the build system. This intermediate
2805 representation is then compiled to a derivation (@pxref{Derivations}).
2807 Build systems accept an optional list of @dfn{arguments}. In package
2808 definitions, these are passed @i{via} the @code{arguments} field
2809 (@pxref{Defining Packages}). They are typically keyword arguments
2810 (@pxref{Optional Arguments, keyword arguments in Guile,, guile, GNU
2811 Guile Reference Manual}). The value of these arguments is usually
2812 evaluated in the @dfn{build stratum}---i.e., by a Guile process launched
2813 by the daemon (@pxref{Derivations}).
2815 The main build system is @var{gnu-build-system}, which implements the
2816 standard build procedure for GNU and many other packages. It
2817 is provided by the @code{(guix build-system gnu)} module.
2819 @defvr {Scheme Variable} gnu-build-system
2820 @var{gnu-build-system} represents the GNU Build System, and variants
2821 thereof (@pxref{Configuration, configuration and makefile conventions,,
2822 standards, GNU Coding Standards}).
2824 @cindex build phases
2825 In a nutshell, packages using it are configured, built, and installed with
2826 the usual @code{./configure && make && make check && make install}
2827 command sequence. In practice, a few additional steps are often needed.
2828 All these steps are split up in separate @dfn{phases},
2829 notably@footnote{Please see the @code{(guix build gnu-build-system)}
2830 modules for more details about the build phases.}:
2834 Unpack the source tarball, and change the current directory to the
2835 extracted source tree. If the source is actually a directory, copy it
2836 to the build tree, and enter that directory.
2838 @item patch-source-shebangs
2839 Patch shebangs encountered in source files so they refer to the right
2840 store file names. For instance, this changes @code{#!/bin/sh} to
2841 @code{#!/gnu/store/@dots{}-bash-4.3/bin/sh}.
2844 Run the @file{configure} script with a number of default options, such
2845 as @code{--prefix=/gnu/store/@dots{}}, as well as the options specified
2846 by the @code{#:configure-flags} argument.
2849 Run @code{make} with the list of flags specified with
2850 @code{#:make-flags}. If the @code{#:parallel-build?} argument is true
2851 (the default), build with @code{make -j}.
2854 Run @code{make check}, or some other target specified with
2855 @code{#:test-target}, unless @code{#:tests? #f} is passed. If the
2856 @code{#:parallel-tests?} argument is true (the default), run @code{make
2860 Run @code{make install} with the flags listed in @code{#:make-flags}.
2862 @item patch-shebangs
2863 Patch shebangs on the installed executable files.
2866 Strip debugging symbols from ELF files (unless @code{#:strip-binaries?}
2867 is false), copying them to the @code{debug} output when available
2868 (@pxref{Installing Debugging Files}).
2871 @vindex %standard-phases
2872 The build-side module @code{(guix build gnu-build-system)} defines
2873 @var{%standard-phases} as the default list of build phases.
2874 @var{%standard-phases} is a list of symbol/procedure pairs, where the
2875 procedure implements the actual phase.
2877 The list of phases used for a particular package can be changed with the
2878 @code{#:phases} parameter. For instance, passing:
2881 #:phases (modify-phases %standard-phases (delete 'configure))
2884 means that all the phases described above will be used, except the
2885 @code{configure} phase.
2887 In addition, this build system ensures that the ``standard'' environment
2888 for GNU packages is available. This includes tools such as GCC, libc,
2889 Coreutils, Bash, Make, Diffutils, grep, and sed (see the @code{(guix
2890 build-system gnu)} module for a complete list). We call these the
2891 @dfn{implicit inputs} of a package, because package definitions do not
2892 have to mention them.
2895 Other @code{<build-system>} objects are defined to support other
2896 conventions and tools used by free software packages. They inherit most
2897 of @var{gnu-build-system}, and differ mainly in the set of inputs
2898 implicitly added to the build process, and in the list of phases
2899 executed. Some of these build systems are listed below.
2901 @defvr {Scheme Variable} ant-build-system
2902 This variable is exported by @code{(guix build-system ant)}. It
2903 implements the build procedure for Java packages that can be built with
2904 @url{http://ant.apache.org/, Ant build tool}.
2906 It adds both @code{ant} and the @dfn{Java Development Kit} (JDK) as
2907 provided by the @code{icedtea} package to the set of inputs. Different
2908 packages can be specified with the @code{#:ant} and @code{#:jdk}
2909 parameters, respectively.
2911 When the original package does not provide a suitable Ant build file,
2912 the parameter @code{#:jar-name} can be used to generate a minimal Ant
2913 build file @file{build.xml} with tasks to build the specified jar
2916 The parameter @code{#:build-target} can be used to specify the Ant task
2917 that should be run during the @code{build} phase. By default the
2918 ``jar'' task will be run.
2922 @defvr {Scheme Variable} cmake-build-system
2923 This variable is exported by @code{(guix build-system cmake)}. It
2924 implements the build procedure for packages using the
2925 @url{http://www.cmake.org, CMake build tool}.
2927 It automatically adds the @code{cmake} package to the set of inputs.
2928 Which package is used can be specified with the @code{#:cmake}
2931 The @code{#:configure-flags} parameter is taken as a list of flags
2932 passed to the @command{cmake} command. The @code{#:build-type}
2933 parameter specifies in abstract terms the flags passed to the compiler;
2934 it defaults to @code{"RelWithDebInfo"} (short for ``release mode with
2935 debugging information''), which roughly means that code is compiled with
2936 @code{-O2 -g}, as is the case for Autoconf-based packages by default.
2939 @defvr {Scheme Variable} glib-or-gtk-build-system
2940 This variable is exported by @code{(guix build-system glib-or-gtk)}. It
2941 is intended for use with packages making use of GLib or GTK+.
2943 This build system adds the following two phases to the ones defined by
2944 @var{gnu-build-system}:
2947 @item glib-or-gtk-wrap
2948 The phase @code{glib-or-gtk-wrap} ensures that programs in
2949 @file{bin/} are able to find GLib ``schemas'' and
2950 @uref{https://developer.gnome.org/gtk3/stable/gtk-running.html, GTK+
2951 modules}. This is achieved by wrapping the programs in launch scripts
2952 that appropriately set the @code{XDG_DATA_DIRS} and @code{GTK_PATH}
2953 environment variables.
2955 It is possible to exclude specific package outputs from that wrapping
2956 process by listing their names in the
2957 @code{#:glib-or-gtk-wrap-excluded-outputs} parameter. This is useful
2958 when an output is known not to contain any GLib or GTK+ binaries, and
2959 where wrapping would gratuitously add a dependency of that output on
2962 @item glib-or-gtk-compile-schemas
2963 The phase @code{glib-or-gtk-compile-schemas} makes sure that all
2964 @uref{https://developer.gnome.org/gio/stable/glib-compile-schemas.html,
2965 GSettings schemas} of GLib are compiled. Compilation is performed by the
2966 @command{glib-compile-schemas} program. It is provided by the package
2967 @code{glib:bin} which is automatically imported by the build system.
2968 The @code{glib} package providing @command{glib-compile-schemas} can be
2969 specified with the @code{#:glib} parameter.
2972 Both phases are executed after the @code{install} phase.
2975 @defvr {Scheme Variable} python-build-system
2976 This variable is exported by @code{(guix build-system python)}. It
2977 implements the more or less standard build procedure used by Python
2978 packages, which consists in running @code{python setup.py build} and
2979 then @code{python setup.py install --prefix=/gnu/store/@dots{}}.
2981 For packages that install stand-alone Python programs under @code{bin/},
2982 it takes care of wrapping these programs so that their @code{PYTHONPATH}
2983 environment variable points to all the Python libraries they depend on.
2985 Which Python package is used to perform the build can be specified with
2986 the @code{#:python} parameter. This is a useful way to force a package
2987 to be built for a specific version of the Python interpreter, which
2988 might be necessary if the package is only compatible with a single
2989 interpreter version.
2992 @defvr {Scheme Variable} perl-build-system
2993 This variable is exported by @code{(guix build-system perl)}. It
2994 implements the standard build procedure for Perl packages, which either
2995 consists in running @code{perl Build.PL --prefix=/gnu/store/@dots{}},
2996 followed by @code{Build} and @code{Build install}; or in running
2997 @code{perl Makefile.PL PREFIX=/gnu/store/@dots{}}, followed by
2998 @code{make} and @code{make install}, depending on which of
2999 @code{Build.PL} or @code{Makefile.PL} is present in the package
3000 distribution. Preference is given to the former if both @code{Build.PL}
3001 and @code{Makefile.PL} exist in the package distribution. This
3002 preference can be reversed by specifying @code{#t} for the
3003 @code{#:make-maker?} parameter.
3005 The initial @code{perl Makefile.PL} or @code{perl Build.PL} invocation
3006 passes flags specified by the @code{#:make-maker-flags} or
3007 @code{#:module-build-flags} parameter, respectively.
3009 Which Perl package is used can be specified with @code{#:perl}.
3012 @defvr {Scheme Variable} r-build-system
3013 This variable is exported by @code{(guix build-system r)}. It
3014 implements the build procedure used by @uref{http://r-project.org, R}
3015 packages, which essentially is little more than running @code{R CMD
3016 INSTALL --library=/gnu/store/@dots{}} in an environment where
3017 @code{R_LIBS_SITE} contains the paths to all R package inputs. Tests
3018 are run after installation using the R function
3019 @code{tools::testInstalledPackage}.
3022 @defvr {Scheme Variable} ruby-build-system
3023 This variable is exported by @code{(guix build-system ruby)}. It
3024 implements the RubyGems build procedure used by Ruby packages, which
3025 involves running @code{gem build} followed by @code{gem install}.
3027 The @code{source} field of a package that uses this build system
3028 typically references a gem archive, since this is the format that Ruby
3029 developers use when releasing their software. The build system unpacks
3030 the gem archive, potentially patches the source, runs the test suite,
3031 repackages the gem, and installs it. Additionally, directories and
3032 tarballs may be referenced to allow building unreleased gems from Git or
3033 a traditional source release tarball.
3035 Which Ruby package is used can be specified with the @code{#:ruby}
3036 parameter. A list of additional flags to be passed to the @command{gem}
3037 command can be specified with the @code{#:gem-flags} parameter.
3040 @defvr {Scheme Variable} waf-build-system
3041 This variable is exported by @code{(guix build-system waf)}. It
3042 implements a build procedure around the @code{waf} script. The common
3043 phases---@code{configure}, @code{build}, and @code{install}---are
3044 implemented by passing their names as arguments to the @code{waf}
3047 The @code{waf} script is executed by the Python interpreter. Which
3048 Python package is used to run the script can be specified with the
3049 @code{#:python} parameter.
3052 @defvr {Scheme Variable} haskell-build-system
3053 This variable is exported by @code{(guix build-system haskell)}. It
3054 implements the Cabal build procedure used by Haskell packages, which
3055 involves running @code{runhaskell Setup.hs configure
3056 --prefix=/gnu/store/@dots{}} and @code{runhaskell Setup.hs build}.
3057 Instead of installing the package by running @code{runhaskell Setup.hs
3058 install}, to avoid trying to register libraries in the read-only
3059 compiler store directory, the build system uses @code{runhaskell
3060 Setup.hs copy}, followed by @code{runhaskell Setup.hs register}. In
3061 addition, the build system generates the package documentation by
3062 running @code{runhaskell Setup.hs haddock}, unless @code{#:haddock? #f}
3063 is passed. Optional Haddock parameters can be passed with the help of
3064 the @code{#:haddock-flags} parameter. If the file @code{Setup.hs} is
3065 not found, the build system looks for @code{Setup.lhs} instead.
3067 Which Haskell compiler is used can be specified with the @code{#:haskell}
3068 parameter which defaults to @code{ghc}.
3071 @defvr {Scheme Variable} emacs-build-system
3072 This variable is exported by @code{(guix build-system emacs)}. It
3073 implements an installation procedure similar to the packaging system
3074 of Emacs itself (@pxref{Packages,,, emacs, The GNU Emacs Manual}).
3076 It first creates the @code{@var{package}-autoloads.el} file, then it
3077 byte compiles all Emacs Lisp files. Differently from the Emacs
3078 packaging system, the Info documentation files are moved to the standard
3079 documentation directory and the @file{dir} file is deleted. Each
3080 package is installed in its own directory under
3081 @file{share/emacs/site-lisp/guix.d}.
3084 Lastly, for packages that do not need anything as sophisticated, a
3085 ``trivial'' build system is provided. It is trivial in the sense that
3086 it provides basically no support: it does not pull any implicit inputs,
3087 and does not have a notion of build phases.
3089 @defvr {Scheme Variable} trivial-build-system
3090 This variable is exported by @code{(guix build-system trivial)}.
3092 This build system requires a @code{#:builder} argument. This argument
3093 must be a Scheme expression that builds the package output(s)---as
3094 with @code{build-expression->derivation} (@pxref{Derivations,
3095 @code{build-expression->derivation}}).
3105 Conceptually, the @dfn{store} is the place where derivations that have
3106 been built successfully are stored---by default, @file{/gnu/store}.
3107 Sub-directories in the store are referred to as @dfn{store items} or
3108 sometimes @dfn{store paths}. The store has an associated database that
3109 contains information such as the store paths referred to by each store
3110 path, and the list of @emph{valid} store items---results of successful
3111 builds. This database resides in @file{@var{localstatedir}/guix/db},
3112 where @var{localstatedir} is the state directory specified @i{via}
3113 @option{--localstatedir} at configure time, usually @file{/var}.
3115 The store is @emph{always} accessed by the daemon on behalf of its clients
3116 (@pxref{Invoking guix-daemon}). To manipulate the store, clients
3117 connect to the daemon over a Unix-domain socket, send requests to it,
3118 and read the result---these are remote procedure calls, or RPCs.
3121 Users must @emph{never} modify files under @file{/gnu/store} directly.
3122 This would lead to inconsistencies and break the immutability
3123 assumptions of Guix's functional model (@pxref{Introduction}).
3125 @xref{Invoking guix gc, @command{guix gc --verify}}, for information on
3126 how to check the integrity of the store and attempt recovery from
3127 accidental modifications.
3130 The @code{(guix store)} module provides procedures to connect to the
3131 daemon, and to perform RPCs. These are described below.
3133 @deffn {Scheme Procedure} open-connection [@var{file}] [#:reserve-space? #t]
3134 Connect to the daemon over the Unix-domain socket at @var{file}. When
3135 @var{reserve-space?} is true, instruct it to reserve a little bit of
3136 extra space on the file system so that the garbage collector can still
3137 operate should the disk become full. Return a server object.
3139 @var{file} defaults to @var{%default-socket-path}, which is the normal
3140 location given the options that were passed to @command{configure}.
3143 @deffn {Scheme Procedure} close-connection @var{server}
3144 Close the connection to @var{server}.
3147 @defvr {Scheme Variable} current-build-output-port
3148 This variable is bound to a SRFI-39 parameter, which refers to the port
3149 where build and error logs sent by the daemon should be written.
3152 Procedures that make RPCs all take a server object as their first
3155 @deffn {Scheme Procedure} valid-path? @var{server} @var{path}
3156 @cindex invalid store items
3157 Return @code{#t} when @var{path} designates a valid store item and
3158 @code{#f} otherwise (an invalid item may exist on disk but still be
3159 invalid, for instance because it is the result of an aborted or failed
3162 A @code{&nix-protocol-error} condition is raised if @var{path} is not
3163 prefixed by the store directory (@file{/gnu/store}).
3166 @deffn {Scheme Procedure} add-text-to-store @var{server} @var{name} @var{text} [@var{references}]
3167 Add @var{text} under file @var{name} in the store, and return its store
3168 path. @var{references} is the list of store paths referred to by the
3169 resulting store path.
3172 @deffn {Scheme Procedure} build-derivations @var{server} @var{derivations}
3173 Build @var{derivations} (a list of @code{<derivation>} objects or
3174 derivation paths), and return when the worker is done building them.
3175 Return @code{#t} on success.
3178 Note that the @code{(guix monads)} module provides a monad as well as
3179 monadic versions of the above procedures, with the goal of making it
3180 more convenient to work with code that accesses the store (@pxref{The
3184 @i{This section is currently incomplete.}
3187 @section Derivations
3190 Low-level build actions and the environment in which they are performed
3191 are represented by @dfn{derivations}. A derivation contains the
3192 following pieces of information:
3196 The outputs of the derivation---derivations produce at least one file or
3197 directory in the store, but may produce more.
3200 The inputs of the derivations, which may be other derivations or plain
3201 files in the store (patches, build scripts, etc.)
3204 The system type targeted by the derivation---e.g., @code{x86_64-linux}.
3207 The file name of a build script in the store, along with the arguments
3211 A list of environment variables to be defined.
3215 @cindex derivation path
3216 Derivations allow clients of the daemon to communicate build actions to
3217 the store. They exist in two forms: as an in-memory representation,
3218 both on the client- and daemon-side, and as files in the store whose
3219 name end in @code{.drv}---these files are referred to as @dfn{derivation
3220 paths}. Derivations paths can be passed to the @code{build-derivations}
3221 procedure to perform the build actions they prescribe (@pxref{The
3224 The @code{(guix derivations)} module provides a representation of
3225 derivations as Scheme objects, along with procedures to create and
3226 otherwise manipulate derivations. The lowest-level primitive to create
3227 a derivation is the @code{derivation} procedure:
3229 @deffn {Scheme Procedure} derivation @var{store} @var{name} @var{builder} @
3230 @var{args} [#:outputs '("out")] [#:hash #f] [#:hash-algo #f] @
3231 [#:recursive? #f] [#:inputs '()] [#:env-vars '()] @
3232 [#:system (%current-system)] [#:references-graphs #f] @
3233 [#:allowed-references #f] [#:disallowed-references #f] @
3234 [#:leaked-env-vars #f] [#:local-build? #f] @
3235 [#:substitutable? #t]
3236 Build a derivation with the given arguments, and return the resulting
3237 @code{<derivation>} object.
3239 When @var{hash} and @var{hash-algo} are given, a
3240 @dfn{fixed-output derivation} is created---i.e., one whose result is
3241 known in advance, such as a file download. If, in addition,
3242 @var{recursive?} is true, then that fixed output may be an executable
3243 file or a directory and @var{hash} must be the hash of an archive
3244 containing this output.
3246 When @var{references-graphs} is true, it must be a list of file
3247 name/store path pairs. In that case, the reference graph of each store
3248 path is exported in the build environment in the corresponding file, in
3249 a simple text format.
3251 When @var{allowed-references} is true, it must be a list of store items
3252 or outputs that the derivation's output may refer to. Likewise,
3253 @var{disallowed-references}, if true, must be a list of things the
3254 outputs may @emph{not} refer to.
3256 When @var{leaked-env-vars} is true, it must be a list of strings
3257 denoting environment variables that are allowed to ``leak'' from the
3258 daemon's environment to the build environment. This is only applicable
3259 to fixed-output derivations---i.e., when @var{hash} is true. The main
3260 use is to allow variables such as @code{http_proxy} to be passed to
3261 derivations that download files.
3263 When @var{local-build?} is true, declare that the derivation is not a
3264 good candidate for offloading and should rather be built locally
3265 (@pxref{Daemon Offload Setup}). This is the case for small derivations
3266 where the costs of data transfers would outweigh the benefits.
3268 When @var{substitutable?} is false, declare that substitutes of the
3269 derivation's output should not be used (@pxref{Substitutes}). This is
3270 useful, for instance, when building packages that capture details of the
3271 host CPU instruction set.
3275 Here's an example with a shell script as its builder, assuming
3276 @var{store} is an open connection to the daemon, and @var{bash} points
3277 to a Bash executable in the store:
3280 (use-modules (guix utils)
3284 (let ((builder ; add the Bash script to the store
3285 (add-text-to-store store "my-builder.sh"
3286 "echo hello world > $out\n" '())))
3287 (derivation store "foo"
3288 bash `("-e" ,builder)
3289 #:inputs `((,bash) (,builder))
3290 #:env-vars '(("HOME" . "/homeless"))))
3291 @result{} #<derivation /gnu/store/@dots{}-foo.drv => /gnu/store/@dots{}-foo>
3294 As can be guessed, this primitive is cumbersome to use directly. A
3295 better approach is to write build scripts in Scheme, of course! The
3296 best course of action for that is to write the build code as a
3297 ``G-expression'', and to pass it to @code{gexp->derivation}. For more
3298 information, @pxref{G-Expressions}.
3300 Once upon a time, @code{gexp->derivation} did not exist and constructing
3301 derivations with build code written in Scheme was achieved with
3302 @code{build-expression->derivation}, documented below. This procedure
3303 is now deprecated in favor of the much nicer @code{gexp->derivation}.
3305 @deffn {Scheme Procedure} build-expression->derivation @var{store} @
3306 @var{name} @var{exp} @
3307 [#:system (%current-system)] [#:inputs '()] @
3308 [#:outputs '("out")] [#:hash #f] [#:hash-algo #f] @
3309 [#:recursive? #f] [#:env-vars '()] [#:modules '()] @
3310 [#:references-graphs #f] [#:allowed-references #f] @
3311 [#:disallowed-references #f] @
3312 [#:local-build? #f] [#:substitutable? #t] [#:guile-for-build #f]
3313 Return a derivation that executes Scheme expression @var{exp} as a
3314 builder for derivation @var{name}. @var{inputs} must be a list of
3315 @code{(name drv-path sub-drv)} tuples; when @var{sub-drv} is omitted,
3316 @code{"out"} is assumed. @var{modules} is a list of names of Guile
3317 modules from the current search path to be copied in the store,
3318 compiled, and made available in the load path during the execution of
3319 @var{exp}---e.g., @code{((guix build utils) (guix build
3320 gnu-build-system))}.
3322 @var{exp} is evaluated in an environment where @code{%outputs} is bound
3323 to a list of output/path pairs, and where @code{%build-inputs} is bound
3324 to a list of string/output-path pairs made from @var{inputs}.
3325 Optionally, @var{env-vars} is a list of string pairs specifying the name
3326 and value of environment variables visible to the builder. The builder
3327 terminates by passing the result of @var{exp} to @code{exit}; thus, when
3328 @var{exp} returns @code{#f}, the build is considered to have failed.
3330 @var{exp} is built using @var{guile-for-build} (a derivation). When
3331 @var{guile-for-build} is omitted or is @code{#f}, the value of the
3332 @code{%guile-for-build} fluid is used instead.
3334 See the @code{derivation} procedure for the meaning of
3335 @var{references-graphs}, @var{allowed-references},
3336 @var{disallowed-references}, @var{local-build?}, and
3337 @var{substitutable?}.
3341 Here's an example of a single-output derivation that creates a directory
3342 containing one file:
3345 (let ((builder '(let ((out (assoc-ref %outputs "out")))
3346 (mkdir out) ; create /gnu/store/@dots{}-goo
3347 (call-with-output-file (string-append out "/test")
3349 (display '(hello guix) p))))))
3350 (build-expression->derivation store "goo" builder))
3352 @result{} #<derivation /gnu/store/@dots{}-goo.drv => @dots{}>
3356 @node The Store Monad
3357 @section The Store Monad
3361 The procedures that operate on the store described in the previous
3362 sections all take an open connection to the build daemon as their first
3363 argument. Although the underlying model is functional, they either have
3364 side effects or depend on the current state of the store.
3366 The former is inconvenient: the connection to the build daemon has to be
3367 carried around in all those functions, making it impossible to compose
3368 functions that do not take that parameter with functions that do. The
3369 latter can be problematic: since store operations have side effects
3370 and/or depend on external state, they have to be properly sequenced.
3372 @cindex monadic values
3373 @cindex monadic functions
3374 This is where the @code{(guix monads)} module comes in. This module
3375 provides a framework for working with @dfn{monads}, and a particularly
3376 useful monad for our uses, the @dfn{store monad}. Monads are a
3377 construct that allows two things: associating ``context'' with values
3378 (in our case, the context is the store), and building sequences of
3379 computations (here computations include accesses to the store). Values
3380 in a monad---values that carry this additional context---are called
3381 @dfn{monadic values}; procedures that return such values are called
3382 @dfn{monadic procedures}.
3384 Consider this ``normal'' procedure:
3387 (define (sh-symlink store)
3388 ;; Return a derivation that symlinks the 'bash' executable.
3389 (let* ((drv (package-derivation store bash))
3390 (out (derivation->output-path drv))
3391 (sh (string-append out "/bin/bash")))
3392 (build-expression->derivation store "sh"
3393 `(symlink ,sh %output))))
3396 Using @code{(guix monads)} and @code{(guix gexp)}, it may be rewritten
3397 as a monadic function:
3400 (define (sh-symlink)
3401 ;; Same, but return a monadic value.
3402 (mlet %store-monad ((drv (package->derivation bash)))
3403 (gexp->derivation "sh"
3404 #~(symlink (string-append #$drv "/bin/bash")
3408 There are several things to note in the second version: the @code{store}
3409 parameter is now implicit and is ``threaded'' in the calls to the
3410 @code{package->derivation} and @code{gexp->derivation} monadic
3411 procedures, and the monadic value returned by @code{package->derivation}
3412 is @dfn{bound} using @code{mlet} instead of plain @code{let}.
3414 As it turns out, the call to @code{package->derivation} can even be
3415 omitted since it will take place implicitly, as we will see later
3416 (@pxref{G-Expressions}):
3419 (define (sh-symlink)
3420 (gexp->derivation "sh"
3421 #~(symlink (string-append #$bash "/bin/bash")
3426 @c <https://syntaxexclamation.wordpress.com/2014/06/26/escaping-continuations/>
3427 @c for the funny quote.
3428 Calling the monadic @code{sh-symlink} has no effect. As someone once
3429 said, ``you exit a monad like you exit a building on fire: by running''.
3430 So, to exit the monad and get the desired effect, one must use
3431 @code{run-with-store}:
3434 (run-with-store (open-connection) (sh-symlink))
3435 @result{} /gnu/store/...-sh-symlink
3438 Note that the @code{(guix monad-repl)} module extends the Guile REPL with
3439 new ``meta-commands'' to make it easier to deal with monadic procedures:
3440 @code{run-in-store}, and @code{enter-store-monad}. The former is used
3441 to ``run'' a single monadic value through the store:
3444 scheme@@(guile-user)> ,run-in-store (package->derivation hello)
3445 $1 = #<derivation /gnu/store/@dots{}-hello-2.9.drv => @dots{}>
3448 The latter enters a recursive REPL, where all the return values are
3449 automatically run through the store:
3452 scheme@@(guile-user)> ,enter-store-monad
3453 store-monad@@(guile-user) [1]> (package->derivation hello)
3454 $2 = #<derivation /gnu/store/@dots{}-hello-2.9.drv => @dots{}>
3455 store-monad@@(guile-user) [1]> (text-file "foo" "Hello!")
3456 $3 = "/gnu/store/@dots{}-foo"
3457 store-monad@@(guile-user) [1]> ,q
3458 scheme@@(guile-user)>
3462 Note that non-monadic values cannot be returned in the
3463 @code{store-monad} REPL.
3465 The main syntactic forms to deal with monads in general are provided by
3466 the @code{(guix monads)} module and are described below.
3468 @deffn {Scheme Syntax} with-monad @var{monad} @var{body} ...
3469 Evaluate any @code{>>=} or @code{return} forms in @var{body} as being
3473 @deffn {Scheme Syntax} return @var{val}
3474 Return a monadic value that encapsulates @var{val}.
3477 @deffn {Scheme Syntax} >>= @var{mval} @var{mproc} ...
3478 @dfn{Bind} monadic value @var{mval}, passing its ``contents'' to monadic
3479 procedures @var{mproc}@dots{}@footnote{This operation is commonly
3480 referred to as ``bind'', but that name denotes an unrelated procedure in
3481 Guile. Thus we use this somewhat cryptic symbol inherited from the
3482 Haskell language.}. There can be one @var{mproc} or several of them, as
3487 (with-monad %state-monad
3489 (lambda (x) (return (+ 1 x)))
3490 (lambda (x) (return (* 2 x)))))
3494 @result{} some-state
3498 @deffn {Scheme Syntax} mlet @var{monad} ((@var{var} @var{mval}) ...) @
3500 @deffnx {Scheme Syntax} mlet* @var{monad} ((@var{var} @var{mval}) ...) @
3502 Bind the variables @var{var} to the monadic values @var{mval} in
3503 @var{body}. The form (@var{var} -> @var{val}) binds @var{var} to the
3504 ``normal'' value @var{val}, as per @code{let}.
3506 @code{mlet*} is to @code{mlet} what @code{let*} is to @code{let}
3507 (@pxref{Local Bindings,,, guile, GNU Guile Reference Manual}).
3510 @deffn {Scheme System} mbegin @var{monad} @var{mexp} ...
3511 Bind @var{mexp} and the following monadic expressions in sequence,
3512 returning the result of the last expression.
3514 This is akin to @code{mlet}, except that the return values of the
3515 monadic expressions are ignored. In that sense, it is analogous to
3516 @code{begin}, but applied to monadic expressions.
3520 The @code{(guix monads)} module provides the @dfn{state monad}, which
3521 allows an additional value---the state---to be @emph{threaded} through
3522 monadic procedure calls.
3524 @defvr {Scheme Variable} %state-monad
3525 The state monad. Procedures in the state monad can access and change
3526 the state that is threaded.
3528 Consider the example below. The @code{square} procedure returns a value
3529 in the state monad. It returns the square of its argument, but also
3530 increments the current state value:
3534 (mlet %state-monad ((count (current-state)))
3535 (mbegin %state-monad
3536 (set-current-state (+ 1 count))
3539 (run-with-state (sequence %state-monad (map square (iota 3))) 0)
3544 When ``run'' through @var{%state-monad}, we obtain that additional state
3545 value, which is the number of @code{square} calls.
3548 @deffn {Monadic Procedure} current-state
3549 Return the current state as a monadic value.
3552 @deffn {Monadic Procedure} set-current-state @var{value}
3553 Set the current state to @var{value} and return the previous state as a
3557 @deffn {Monadic Procedure} state-push @var{value}
3558 Push @var{value} to the current state, which is assumed to be a list,
3559 and return the previous state as a monadic value.
3562 @deffn {Monadic Procedure} state-pop
3563 Pop a value from the current state and return it as a monadic value.
3564 The state is assumed to be a list.
3567 @deffn {Scheme Procedure} run-with-state @var{mval} [@var{state}]
3568 Run monadic value @var{mval} starting with @var{state} as the initial
3569 state. Return two values: the resulting value, and the resulting state.
3572 The main interface to the store monad, provided by the @code{(guix
3573 store)} module, is as follows.
3575 @defvr {Scheme Variable} %store-monad
3576 The store monad---an alias for @var{%state-monad}.
3578 Values in the store monad encapsulate accesses to the store. When its
3579 effect is needed, a value of the store monad must be ``evaluated'' by
3580 passing it to the @code{run-with-store} procedure (see below.)
3583 @deffn {Scheme Procedure} run-with-store @var{store} @var{mval} [#:guile-for-build] [#:system (%current-system)]
3584 Run @var{mval}, a monadic value in the store monad, in @var{store}, an
3585 open store connection.
3588 @deffn {Monadic Procedure} text-file @var{name} @var{text} [@var{references}]
3589 Return as a monadic value the absolute file name in the store of the file
3590 containing @var{text}, a string. @var{references} is a list of store items that the
3591 resulting text file refers to; it defaults to the empty list.
3594 @deffn {Monadic Procedure} interned-file @var{file} [@var{name}] @
3595 [#:recursive? #t] [#:select? (const #t)]
3596 Return the name of @var{file} once interned in the store. Use
3597 @var{name} as its store name, or the basename of @var{file} if
3598 @var{name} is omitted.
3600 When @var{recursive?} is true, the contents of @var{file} are added
3601 recursively; if @var{file} designates a flat file and @var{recursive?}
3602 is true, its contents are added, and its permission bits are kept.
3604 When @var{recursive?} is true, call @code{(@var{select?} @var{file}
3605 @var{stat})} for each directory entry, where @var{file} is the entry's
3606 absolute file name and @var{stat} is the result of @code{lstat}; exclude
3607 entries for which @var{select?} does not return true.
3609 The example below adds a file to the store, under two different names:
3612 (run-with-store (open-connection)
3613 (mlet %store-monad ((a (interned-file "README"))
3614 (b (interned-file "README" "LEGU-MIN")))
3615 (return (list a b))))
3617 @result{} ("/gnu/store/rwm@dots{}-README" "/gnu/store/44i@dots{}-LEGU-MIN")
3622 The @code{(guix packages)} module exports the following package-related
3625 @deffn {Monadic Procedure} package-file @var{package} [@var{file}] @
3626 [#:system (%current-system)] [#:target #f] @
3629 value in the absolute file name of @var{file} within the @var{output}
3630 directory of @var{package}. When @var{file} is omitted, return the name
3631 of the @var{output} directory of @var{package}. When @var{target} is
3632 true, use it as a cross-compilation target triplet.
3635 @deffn {Monadic Procedure} package->derivation @var{package} [@var{system}]
3636 @deffnx {Monadic Procedure} package->cross-derivation @var{package} @
3637 @var{target} [@var{system}]
3638 Monadic version of @code{package-derivation} and
3639 @code{package-cross-derivation} (@pxref{Defining Packages}).
3644 @section G-Expressions
3646 @cindex G-expression
3647 @cindex build code quoting
3648 So we have ``derivations'', which represent a sequence of build actions
3649 to be performed to produce an item in the store (@pxref{Derivations}).
3650 These build actions are performed when asking the daemon to actually
3651 build the derivations; they are run by the daemon in a container
3652 (@pxref{Invoking guix-daemon}).
3654 @cindex strata of code
3655 It should come as no surprise that we like to write these build actions
3656 in Scheme. When we do that, we end up with two @dfn{strata} of Scheme
3657 code@footnote{The term @dfn{stratum} in this context was coined by
3658 Manuel Serrano et al.@: in the context of their work on Hop. Oleg
3659 Kiselyov, who has written insightful
3660 @url{http://okmij.org/ftp/meta-programming/#meta-scheme, essays and code
3661 on this topic}, refers to this kind of code generation as
3662 @dfn{staging}.}: the ``host code''---code that defines packages, talks
3663 to the daemon, etc.---and the ``build code''---code that actually
3664 performs build actions, such as making directories, invoking
3665 @command{make}, etc.
3667 To describe a derivation and its build actions, one typically needs to
3668 embed build code inside host code. It boils down to manipulating build
3669 code as data, and the homoiconicity of Scheme---code has a direct
3670 representation as data---comes in handy for that. But we need more than
3671 the normal @code{quasiquote} mechanism in Scheme to construct build
3674 The @code{(guix gexp)} module implements @dfn{G-expressions}, a form of
3675 S-expressions adapted to build expressions. G-expressions, or
3676 @dfn{gexps}, consist essentially of three syntactic forms: @code{gexp},
3677 @code{ungexp}, and @code{ungexp-splicing} (or simply: @code{#~},
3678 @code{#$}, and @code{#$@@}), which are comparable to
3679 @code{quasiquote}, @code{unquote}, and @code{unquote-splicing},
3680 respectively (@pxref{Expression Syntax, @code{quasiquote},, guile,
3681 GNU Guile Reference Manual}). However, there are major differences:
3685 Gexps are meant to be written to a file and run or manipulated by other
3689 When a high-level object such as a package or derivation is unquoted
3690 inside a gexp, the result is as if its output file name had been
3694 Gexps carry information about the packages or derivations they refer to,
3695 and these dependencies are automatically added as inputs to the build
3696 processes that use them.
3699 @cindex lowering, of high-level objects in gexps
3700 This mechanism is not limited to package and derivation
3701 objects: @dfn{compilers} able to ``lower'' other high-level objects to
3702 derivations or files in the store can be defined,
3703 such that these objects can also be inserted
3704 into gexps. For example, a useful type of high-level objects that can be
3705 inserted in a gexp is ``file-like objects'', which make it easy to
3706 add files to the store and to refer to them in
3707 derivations and such (see @code{local-file} and @code{plain-file}
3710 To illustrate the idea, here is an example of a gexp:
3717 (symlink (string-append #$coreutils "/bin/ls")
3721 This gexp can be passed to @code{gexp->derivation}; we obtain a
3722 derivation that builds a directory containing exactly one symlink to
3723 @file{/gnu/store/@dots{}-coreutils-8.22/bin/ls}:
3726 (gexp->derivation "the-thing" build-exp)
3729 As one would expect, the @code{"/gnu/store/@dots{}-coreutils-8.22"} string is
3730 substituted to the reference to the @var{coreutils} package in the
3731 actual build code, and @var{coreutils} is automatically made an input to
3732 the derivation. Likewise, @code{#$output} (equivalent to @code{(ungexp
3733 output)}) is replaced by a string containing the directory name of the
3734 output of the derivation.
3736 @cindex cross compilation
3737 In a cross-compilation context, it is useful to distinguish between
3738 references to the @emph{native} build of a package---that can run on the
3739 host---versus references to cross builds of a package. To that end, the
3740 @code{#+} plays the same role as @code{#$}, but is a reference to a
3741 native package build:
3744 (gexp->derivation "vi"
3747 (system* (string-append #+coreutils "/bin/ln")
3749 (string-append #$emacs "/bin/emacs")
3750 (string-append #$output "/bin/vi")))
3751 #:target "mips64el-linux")
3755 In the example above, the native build of @var{coreutils} is used, so
3756 that @command{ln} can actually run on the host; but then the
3757 cross-compiled build of @var{emacs} is referenced.
3759 @cindex imported modules, for gexps
3760 @findex with-imported-modules
3761 Another gexp feature is @dfn{imported modules}: sometimes you want to be
3762 able to use certain Guile modules from the ``host environment'' in the
3763 gexp, so those modules should be imported in the ``build environment''.
3764 The @code{with-imported-modules} form allows you to express that:
3767 (let ((build (with-imported-modules '((guix build utils))
3769 (use-modules (guix build utils))
3770 (mkdir-p (string-append #$output "/bin"))))))
3771 (gexp->derivation "empty-dir"
3774 (display "success!\n")
3779 In this example, the @code{(guix build utils)} module is automatically
3780 pulled into the isolated build environment of our gexp, such that
3781 @code{(use-modules (guix build utils))} works as expected.
3783 The syntactic form to construct gexps is summarized below.
3785 @deffn {Scheme Syntax} #~@var{exp}
3786 @deffnx {Scheme Syntax} (gexp @var{exp})
3787 Return a G-expression containing @var{exp}. @var{exp} may contain one
3788 or more of the following forms:
3792 @itemx (ungexp @var{obj})
3793 Introduce a reference to @var{obj}. @var{obj} may have one of the
3794 supported types, for example a package or a
3795 derivation, in which case the @code{ungexp} form is replaced by its
3796 output file name---e.g., @code{"/gnu/store/@dots{}-coreutils-8.22}.
3798 If @var{obj} is a list, it is traversed and references to supported
3799 objects are substituted similarly.
3801 If @var{obj} is another gexp, its contents are inserted and its
3802 dependencies are added to those of the containing gexp.
3804 If @var{obj} is another kind of object, it is inserted as is.
3806 @item #$@var{obj}:@var{output}
3807 @itemx (ungexp @var{obj} @var{output})
3808 This is like the form above, but referring explicitly to the
3809 @var{output} of @var{obj}---this is useful when @var{obj} produces
3810 multiple outputs (@pxref{Packages with Multiple Outputs}).
3813 @itemx #+@var{obj}:output
3814 @itemx (ungexp-native @var{obj})
3815 @itemx (ungexp-native @var{obj} @var{output})
3816 Same as @code{ungexp}, but produces a reference to the @emph{native}
3817 build of @var{obj} when used in a cross compilation context.
3819 @item #$output[:@var{output}]
3820 @itemx (ungexp output [@var{output}])
3821 Insert a reference to derivation output @var{output}, or to the main
3822 output when @var{output} is omitted.
3824 This only makes sense for gexps passed to @code{gexp->derivation}.
3827 @itemx (ungexp-splicing @var{lst})
3828 Like the above, but splices the contents of @var{lst} inside the
3832 @itemx (ungexp-native-splicing @var{lst})
3833 Like the above, but refers to native builds of the objects listed in
3838 G-expressions created by @code{gexp} or @code{#~} are run-time objects
3839 of the @code{gexp?} type (see below.)
3842 @deffn {Scheme Syntax} with-imported-modules @var{modules} @var{body}@dots{}
3843 Mark the gexps defined in @var{body}@dots{} as requiring @var{modules}
3844 in their execution environment. @var{modules} must be a list of Guile
3845 module names, such as @code{'((guix build utils) (guix build gremlin))}.
3847 This form has @emph{lexical} scope: it has an effect on the gexps
3848 directly defined in @var{body}@dots{}, but not on those defined, say, in
3849 procedures called from @var{body}@dots{}.
3852 @deffn {Scheme Procedure} gexp? @var{obj}
3853 Return @code{#t} if @var{obj} is a G-expression.
3856 G-expressions are meant to be written to disk, either as code building
3857 some derivation, or as plain files in the store. The monadic procedures
3858 below allow you to do that (@pxref{The Store Monad}, for more
3859 information about monads.)
3861 @deffn {Monadic Procedure} gexp->derivation @var{name} @var{exp} @
3862 [#:system (%current-system)] [#:target #f] [#:graft? #t] @
3863 [#:hash #f] [#:hash-algo #f] @
3864 [#:recursive? #f] [#:env-vars '()] [#:modules '()] @
3865 [#:module-path @var{%load-path}] @
3866 [#:references-graphs #f] [#:allowed-references #f] @
3867 [#:disallowed-references #f] @
3868 [#:leaked-env-vars #f] @
3869 [#:script-name (string-append @var{name} "-builder")] @
3870 [#:local-build? #f] [#:substitutable? #t] [#:guile-for-build #f]
3871 Return a derivation @var{name} that runs @var{exp} (a gexp) with
3872 @var{guile-for-build} (a derivation) on @var{system}; @var{exp} is
3873 stored in a file called @var{script-name}. When @var{target} is true,
3874 it is used as the cross-compilation target triplet for packages referred
3877 @var{modules} is deprecated in favor of @code{with-imported-modules}.
3879 make @var{modules} available in the evaluation context of @var{exp};
3880 @var{modules} is a list of names of Guile modules searched in
3881 @var{module-path} to be copied in the store, compiled, and made available in
3882 the load path during the execution of @var{exp}---e.g., @code{((guix
3883 build utils) (guix build gnu-build-system))}.
3885 @var{graft?} determines whether packages referred to by @var{exp} should be grafted when
3888 When @var{references-graphs} is true, it must be a list of tuples of one of the
3892 (@var{file-name} @var{package})
3893 (@var{file-name} @var{package} @var{output})
3894 (@var{file-name} @var{derivation})
3895 (@var{file-name} @var{derivation} @var{output})
3896 (@var{file-name} @var{store-item})
3899 The right-hand-side of each element of @var{references-graphs} is automatically made
3900 an input of the build process of @var{exp}. In the build environment, each
3901 @var{file-name} contains the reference graph of the corresponding item, in a simple
3904 @var{allowed-references} must be either @code{#f} or a list of output names and packages.
3905 In the latter case, the list denotes store items that the result is allowed to
3906 refer to. Any reference to another store item will lead to a build error.
3907 Similarly for @var{disallowed-references}, which can list items that must not be
3908 referenced by the outputs.
3910 The other arguments are as for @code{derivation} (@pxref{Derivations}).
3913 @cindex file-like objects
3914 The @code{local-file}, @code{plain-file}, @code{computed-file},
3915 @code{program-file}, and @code{scheme-file} procedures below return
3916 @dfn{file-like objects}. That is, when unquoted in a G-expression,
3917 these objects lead to a file in the store. Consider this G-expression:
3920 #~(system* (string-append #$glibc "/sbin/nscd") "-f"
3921 #$(local-file "/tmp/my-nscd.conf"))
3924 The effect here is to ``intern'' @file{/tmp/my-nscd.conf} by copying it
3925 to the store. Once expanded, for instance @i{via}
3926 @code{gexp->derivation}, the G-expression refers to that copy under
3927 @file{/gnu/store}; thus, modifying or removing the file in @file{/tmp}
3928 does not have any effect on what the G-expression does.
3929 @code{plain-file} can be used similarly; it differs in that the file
3930 content is directly passed as a string.
3932 @deffn {Scheme Procedure} local-file @var{file} [@var{name}] @
3933 [#:recursive? #f] [#:select? (const #t)]
3934 Return an object representing local file @var{file} to add to the store; this
3935 object can be used in a gexp. If @var{file} is a relative file name, it is looked
3936 up relative to the source file where this form appears. @var{file} will be added to
3937 the store under @var{name}--by default the base name of @var{file}.
3939 When @var{recursive?} is true, the contents of @var{file} are added recursively; if @var{file}
3940 designates a flat file and @var{recursive?} is true, its contents are added, and its
3941 permission bits are kept.
3943 When @var{recursive?} is true, call @code{(@var{select?} @var{file}
3944 @var{stat})} for each directory entry, where @var{file} is the entry's
3945 absolute file name and @var{stat} is the result of @code{lstat}; exclude
3946 entries for which @var{select?} does not return true.
3948 This is the declarative counterpart of the @code{interned-file} monadic
3949 procedure (@pxref{The Store Monad, @code{interned-file}}).
3952 @deffn {Scheme Procedure} plain-file @var{name} @var{content}
3953 Return an object representing a text file called @var{name} with the given
3954 @var{content} (a string) to be added to the store.
3956 This is the declarative counterpart of @code{text-file}.
3959 @deffn {Scheme Procedure} computed-file @var{name} @var{gexp} @
3960 [#:options '(#:local-build? #t)]
3961 Return an object representing the store item @var{name}, a file or
3962 directory computed by @var{gexp}. @var{options}
3963 is a list of additional arguments to pass to @code{gexp->derivation}.
3965 This is the declarative counterpart of @code{gexp->derivation}.
3968 @deffn {Monadic Procedure} gexp->script @var{name} @var{exp}
3969 Return an executable script @var{name} that runs @var{exp} using
3970 @var{guile}, with @var{exp}'s imported modules in its search path.
3972 The example below builds a script that simply invokes the @command{ls}
3976 (use-modules (guix gexp) (gnu packages base))
3978 (gexp->script "list-files"
3979 #~(execl (string-append #$coreutils "/bin/ls")
3983 When ``running'' it through the store (@pxref{The Store Monad,
3984 @code{run-with-store}}), we obtain a derivation that produces an
3985 executable file @file{/gnu/store/@dots{}-list-files} along these lines:
3988 #!/gnu/store/@dots{}-guile-2.0.11/bin/guile -ds
3990 (execl (string-append "/gnu/store/@dots{}-coreutils-8.22"/bin/ls")
3995 @deffn {Scheme Procedure} program-file @var{name} @var{exp} @
3997 Return an object representing the executable store item @var{name} that
3998 runs @var{gexp}. @var{guile} is the Guile package used to execute that
4001 This is the declarative counterpart of @code{gexp->script}.
4004 @deffn {Monadic Procedure} gexp->file @var{name} @var{exp} @
4005 [#:set-load-path? #t]
4006 Return a derivation that builds a file @var{name} containing @var{exp}.
4007 When @var{set-load-path?} is true, emit code in the resulting file to
4008 set @code{%load-path} and @code{%load-compiled-path} to honor
4009 @var{exp}'s imported modules.
4011 The resulting file holds references to all the dependencies of @var{exp}
4012 or a subset thereof.
4015 @deffn {Scheme Procedure} scheme-file @var{name} @var{exp}
4016 Return an object representing the Scheme file @var{name} that contains
4019 This is the declarative counterpart of @code{gexp->file}.
4022 @deffn {Monadic Procedure} text-file* @var{name} @var{text} @dots{}
4023 Return as a monadic value a derivation that builds a text file
4024 containing all of @var{text}. @var{text} may list, in addition to
4025 strings, objects of any type that can be used in a gexp: packages,
4026 derivations, local file objects, etc. The resulting store file holds
4027 references to all these.
4029 This variant should be preferred over @code{text-file} anytime the file
4030 to create will reference items from the store. This is typically the
4031 case when building a configuration file that embeds store file names,
4035 (define (profile.sh)
4036 ;; Return the name of a shell script in the store that
4037 ;; initializes the 'PATH' environment variable.
4038 (text-file* "profile.sh"
4039 "export PATH=" coreutils "/bin:"
4040 grep "/bin:" sed "/bin\n"))
4043 In this example, the resulting @file{/gnu/store/@dots{}-profile.sh} file
4044 will reference @var{coreutils}, @var{grep}, and @var{sed}, thereby
4045 preventing them from being garbage-collected during its lifetime.
4048 @deffn {Scheme Procedure} mixed-text-file @var{name} @var{text} @dots{}
4049 Return an object representing store file @var{name} containing
4050 @var{text}. @var{text} is a sequence of strings and file-like objects,
4054 (mixed-text-file "profile"
4055 "export PATH=" coreutils "/bin:" grep "/bin")
4058 This is the declarative counterpart of @code{text-file*}.
4061 Of course, in addition to gexps embedded in ``host'' code, there are
4062 also modules containing build tools. To make it clear that they are
4063 meant to be used in the build stratum, these modules are kept in the
4064 @code{(guix build @dots{})} name space.
4066 @cindex lowering, of high-level objects in gexps
4067 Internally, high-level objects are @dfn{lowered}, using their compiler,
4068 to either derivations or store items. For instance, lowering a package
4069 yields a derivation, and lowering a @code{plain-file} yields a store
4070 item. This is achieved using the @code{lower-object} monadic procedure.
4072 @deffn {Monadic Procedure} lower-object @var{obj} [@var{system}] @
4074 Return as a value in @var{%store-monad} the derivation or store item
4075 corresponding to @var{obj} for @var{system}, cross-compiling for
4076 @var{target} if @var{target} is true. @var{obj} must be an object that
4077 has an associated gexp compiler, such as a @code{<package>}.
4081 @c *********************************************************************
4085 This section describes Guix command-line utilities. Some of them are
4086 primarily targeted at developers and users who write new package
4087 definitions, while others are more generally useful. They complement
4088 the Scheme programming interface of Guix in a convenient way.
4091 * Invoking guix build:: Building packages from the command line.
4092 * Invoking guix edit:: Editing package definitions.
4093 * Invoking guix download:: Downloading a file and printing its hash.
4094 * Invoking guix hash:: Computing the cryptographic hash of a file.
4095 * Invoking guix import:: Importing package definitions.
4096 * Invoking guix refresh:: Updating package definitions.
4097 * Invoking guix lint:: Finding errors in package definitions.
4098 * Invoking guix size:: Profiling disk usage.
4099 * Invoking guix graph:: Visualizing the graph of packages.
4100 * Invoking guix environment:: Setting up development environments.
4101 * Invoking guix publish:: Sharing substitutes.
4102 * Invoking guix challenge:: Challenging substitute servers.
4103 * Invoking guix container:: Process isolation.
4106 @node Invoking guix build
4107 @section Invoking @command{guix build}
4109 The @command{guix build} command builds packages or derivations and
4110 their dependencies, and prints the resulting store paths. Note that it
4111 does not modify the user's profile---this is the job of the
4112 @command{guix package} command (@pxref{Invoking guix package}). Thus,
4113 it is mainly useful for distribution developers.
4115 The general syntax is:
4118 guix build @var{options} @var{package-or-derivation}@dots{}
4121 As an example, the following command builds the latest versions of Emacs
4122 and of Guile, displays their build logs, and finally displays the
4123 resulting directories:
4126 guix build emacs guile
4129 Similarly, the following command builds all the available packages:
4132 guix build --quiet --keep-going \
4133 `guix package -A | cut -f1,2 --output-delimiter=@@`
4136 @var{package-or-derivation} may be either the name of a package found in
4137 the software distribution such as @code{coreutils} or
4138 @code{coreutils-8.20}, or a derivation such as
4139 @file{/gnu/store/@dots{}-coreutils-8.19.drv}. In the former case, a
4140 package with the corresponding name (and optionally version) is searched
4141 for among the GNU distribution modules (@pxref{Package Modules}).
4143 Alternatively, the @code{--expression} option may be used to specify a
4144 Scheme expression that evaluates to a package; this is useful when
4145 disambiguating among several same-named packages or package variants is
4148 There may be zero or more @var{options}. The available options are
4149 described in the subsections below.
4152 * Common Build Options:: Build options for most commands.
4153 * Package Transformation Options:: Creating variants of packages.
4154 * Additional Build Options:: Options specific to 'guix build'.
4157 @node Common Build Options
4158 @subsection Common Build Options
4160 A number of options that control the build process are common to
4161 @command{guix build} and other commands that can spawn builds, such as
4162 @command{guix package} or @command{guix archive}. These are the
4167 @item --load-path=@var{directory}
4168 @itemx -L @var{directory}
4169 Add @var{directory} to the front of the package module search path
4170 (@pxref{Package Modules}).
4172 This allows users to define their own packages and make them visible to
4173 the command-line tools.
4177 Keep the build tree of failed builds. Thus, if a build fails, its build
4178 tree is kept under @file{/tmp}, in a directory whose name is shown at
4179 the end of the build log. This is useful when debugging build issues.
4183 Keep going when some of the derivations fail to build; return only once
4184 all the builds have either completed or failed.
4186 The default behavior is to stop as soon as one of the specified
4187 derivations has failed.
4191 Do not build the derivations.
4194 When substituting a pre-built binary fails, fall back to building
4197 @item --substitute-urls=@var{urls}
4198 @anchor{client-substitute-urls}
4199 Consider @var{urls} the whitespace-separated list of substitute source
4200 URLs, overriding the default list of URLs of @command{guix-daemon}
4201 (@pxref{daemon-substitute-urls,, @command{guix-daemon} URLs}).
4203 This means that substitutes may be downloaded from @var{urls}, provided
4204 they are signed by a key authorized by the system administrator
4205 (@pxref{Substitutes}).
4207 When @var{urls} is the empty string, substitutes are effectively
4210 @item --no-substitutes
4211 Do not use substitutes for build products. That is, always build things
4212 locally instead of allowing downloads of pre-built binaries
4213 (@pxref{Substitutes}).
4216 Do not ``graft'' packages. In practice, this means that package updates
4217 available as grafts are not applied. @xref{Security Updates}, for more
4218 information on grafts.
4220 @item --rounds=@var{n}
4221 Build each derivation @var{n} times in a row, and raise an error if
4222 consecutive build results are not bit-for-bit identical.
4224 This is a useful way to detect non-deterministic builds processes.
4225 Non-deterministic build processes are a problem because they make it
4226 practically impossible for users to @emph{verify} whether third-party
4227 binaries are genuine. @xref{Invoking guix challenge}, for more.
4229 Note that, currently, the differing build results are not kept around,
4230 so you will have to manually investigate in case of an error---e.g., by
4231 stashing one of the build results with @code{guix archive --export}
4232 (@pxref{Invoking guix archive}), then rebuilding, and finally comparing
4235 @item --no-build-hook
4236 Do not attempt to offload builds @i{via} the ``build hook'' of the daemon
4237 (@pxref{Daemon Offload Setup}). That is, always build things locally
4238 instead of offloading builds to remote machines.
4240 @item --max-silent-time=@var{seconds}
4241 When the build or substitution process remains silent for more than
4242 @var{seconds}, terminate it and report a build failure.
4244 @item --timeout=@var{seconds}
4245 Likewise, when the build or substitution process lasts for more than
4246 @var{seconds}, terminate it and report a build failure.
4248 By default there is no timeout. This behavior can be restored with
4251 @item --verbosity=@var{level}
4252 Use the given verbosity level. @var{level} must be an integer between 0
4253 and 5; higher means more verbose output. Setting a level of 4 or more
4254 may be helpful when debugging setup issues with the build daemon.
4256 @item --cores=@var{n}
4258 Allow the use of up to @var{n} CPU cores for the build. The special
4259 value @code{0} means to use as many CPU cores as available.
4261 @item --max-jobs=@var{n}
4263 Allow at most @var{n} build jobs in parallel. @xref{Invoking
4264 guix-daemon, @code{--max-jobs}}, for details about this option and the
4265 equivalent @command{guix-daemon} option.
4269 Behind the scenes, @command{guix build} is essentially an interface to
4270 the @code{package-derivation} procedure of the @code{(guix packages)}
4271 module, and to the @code{build-derivations} procedure of the @code{(guix
4272 derivations)} module.
4274 In addition to options explicitly passed on the command line,
4275 @command{guix build} and other @command{guix} commands that support
4276 building honor the @code{GUIX_BUILD_OPTIONS} environment variable.
4278 @defvr {Environment Variable} GUIX_BUILD_OPTIONS
4279 Users can define this variable to a list of command line options that
4280 will automatically be used by @command{guix build} and other
4281 @command{guix} commands that can perform builds, as in the example
4285 $ export GUIX_BUILD_OPTIONS="--no-substitutes -c 2 -L /foo/bar"
4288 These options are parsed independently, and the result is appended to
4289 the parsed command-line options.
4293 @node Package Transformation Options
4294 @subsection Package Transformation Options
4296 @cindex package variants
4297 Another set of command-line options supported by @command{guix build}
4298 and also @command{guix package} are @dfn{package transformation
4299 options}. These are options that make it possible to define @dfn{package
4300 variants}---for instance, packages built from different source code.
4301 This is a convenient way to create customized packages on the fly
4302 without having to type in the definitions of package variants
4303 (@pxref{Defining Packages}).
4307 @item --with-source=@var{source}
4308 Use @var{source} as the source of the corresponding package.
4309 @var{source} must be a file name or a URL, as for @command{guix
4310 download} (@pxref{Invoking guix download}).
4312 The ``corresponding package'' is taken to be the one specified on the
4313 command line the name of which matches the base of @var{source}---e.g.,
4314 if @var{source} is @code{/src/guile-2.0.10.tar.gz}, the corresponding
4315 package is @code{guile}. Likewise, the version string is inferred from
4316 @var{source}; in the previous example, it is @code{2.0.10}.
4318 This option allows users to try out versions of packages other than the
4319 one provided by the distribution. The example below downloads
4320 @file{ed-1.7.tar.gz} from a GNU mirror and uses that as the source for
4321 the @code{ed} package:
4324 guix build ed --with-source=mirror://gnu/ed/ed-1.7.tar.gz
4327 As a developer, @code{--with-source} makes it easy to test release
4331 guix build guile --with-source=../guile-2.0.9.219-e1bb7.tar.xz
4334 @dots{} or to build from a checkout in a pristine environment:
4337 $ git clone git://git.sv.gnu.org/guix.git
4338 $ guix build guix --with-source=./guix
4341 @item --with-input=@var{package}=@var{replacement}
4342 Replace dependency on @var{package} by a dependency on
4343 @var{replacement}. @var{package} must be a package name, and
4344 @var{replacement} must be a package specification such as @code{guile}
4345 or @code{guile@@1.8}.
4347 For instance, the following command builds Guix, but replaces its
4348 dependency on the current stable version of Guile with a dependency on
4349 the development version of Guile, @code{guile-next}:
4352 guix build --with-input=guile=guile-next guix
4355 This is a recursive, deep replacement. So in this example, both
4356 @code{guix} and its dependency @code{guile-json} (which also depends on
4357 @code{guile}) get rebuilt against @code{guile-next}.
4359 However, implicit inputs are left unchanged.
4362 @node Additional Build Options
4363 @subsection Additional Build Options
4365 The command-line options presented below are specific to @command{guix
4372 Build quietly, without displaying the build log. Upon completion, the
4373 build log is kept in @file{/var} (or similar) and can always be
4374 retrieved using the @option{--log-file} option.
4376 @item --file=@var{file}
4377 @itemx -f @var{file}
4379 Build the package or derivation that the code within @var{file}
4382 As an example, @var{file} might contain a package definition like this
4383 (@pxref{Defining Packages}):
4386 @verbatiminclude package-hello.scm
4389 @item --expression=@var{expr}
4390 @itemx -e @var{expr}
4391 Build the package or derivation @var{expr} evaluates to.
4393 For example, @var{expr} may be @code{(@@ (gnu packages guile)
4394 guile-1.8)}, which unambiguously designates this specific variant of
4395 version 1.8 of Guile.
4397 Alternatively, @var{expr} may be a G-expression, in which case it is used
4398 as a build program passed to @code{gexp->derivation}
4399 (@pxref{G-Expressions}).
4401 Lastly, @var{expr} may refer to a zero-argument monadic procedure
4402 (@pxref{The Store Monad}). The procedure must return a derivation as a
4403 monadic value, which is then passed through @code{run-with-store}.
4407 Build the source derivations of the packages, rather than the packages
4410 For instance, @code{guix build -S gcc} returns something like
4411 @file{/gnu/store/@dots{}-gcc-4.7.2.tar.bz2}, which is the GCC
4414 The returned source tarball is the result of applying any patches and
4415 code snippets specified in the package @code{origin} (@pxref{Defining
4419 Fetch and return the source of @var{package-or-derivation} and all their
4420 dependencies, recursively. This is a handy way to obtain a local copy
4421 of all the source code needed to build @var{packages}, allowing you to
4422 eventually build them even without network access. It is an extension
4423 of the @code{--source} option and can accept one of the following
4424 optional argument values:
4428 This value causes the @code{--sources} option to behave in the same way
4429 as the @code{--source} option.
4432 Build the source derivations of all packages, including any source that
4433 might be listed as @code{inputs}. This is the default value.
4436 $ guix build --sources tzdata
4437 The following derivations will be built:
4438 /gnu/store/@dots{}-tzdata2015b.tar.gz.drv
4439 /gnu/store/@dots{}-tzcode2015b.tar.gz.drv
4443 Build the source derivations of all packages, as well of all transitive
4444 inputs to the packages. This can be used e.g. to
4445 prefetch package source for later offline building.
4448 $ guix build --sources=transitive tzdata
4449 The following derivations will be built:
4450 /gnu/store/@dots{}-tzcode2015b.tar.gz.drv
4451 /gnu/store/@dots{}-findutils-4.4.2.tar.xz.drv
4452 /gnu/store/@dots{}-grep-2.21.tar.xz.drv
4453 /gnu/store/@dots{}-coreutils-8.23.tar.xz.drv
4454 /gnu/store/@dots{}-make-4.1.tar.xz.drv
4455 /gnu/store/@dots{}-bash-4.3.tar.xz.drv
4461 @item --system=@var{system}
4462 @itemx -s @var{system}
4463 Attempt to build for @var{system}---e.g., @code{i686-linux}---instead of
4464 the system type of the build host.
4466 An example use of this is on Linux-based systems, which can emulate
4467 different personalities. For instance, passing
4468 @code{--system=i686-linux} on an @code{x86_64-linux} system allows users
4469 to build packages in a complete 32-bit environment.
4471 @item --target=@var{triplet}
4472 @cindex cross-compilation
4473 Cross-build for @var{triplet}, which must be a valid GNU triplet, such
4474 as @code{"mips64el-linux-gnu"} (@pxref{Configuration Names, GNU
4475 configuration triplets,, configure, GNU Configure and Build System}).
4477 @anchor{build-check}
4479 @cindex determinism, checking
4480 @cindex reproducibility, checking
4481 Rebuild @var{package-or-derivation}, which are already available in the
4482 store, and raise an error if the build results are not bit-for-bit
4485 This mechanism allows you to check whether previously installed
4486 substitutes are genuine (@pxref{Substitutes}), or whether the build result
4487 of a package is deterministic. @xref{Invoking guix challenge}, for more
4488 background information and tools.
4490 When used in conjunction with @option{--keep-failed}, the differing
4491 output is kept in the store, under @file{/gnu/store/@dots{}-check}.
4492 This makes it easy to look for differences between the two results.
4496 Return the derivation paths, not the output paths, of the given
4499 @item --root=@var{file}
4500 @itemx -r @var{file}
4501 Make @var{file} a symlink to the result, and register it as a garbage
4505 Return the build log file names or URLs for the given
4506 @var{package-or-derivation}, or raise an error if build logs are
4509 This works regardless of how packages or derivations are specified. For
4510 instance, the following invocations are equivalent:
4513 guix build --log-file `guix build -d guile`
4514 guix build --log-file `guix build guile`
4515 guix build --log-file guile
4516 guix build --log-file -e '(@@ (gnu packages guile) guile-2.0)'
4519 If a log is unavailable locally, and unless @code{--no-substitutes} is
4520 passed, the command looks for a corresponding log on one of the
4521 substitute servers (as specified with @code{--substitute-urls}.)
4523 So for instance, imagine you want to see the build log of GDB on MIPS,
4524 but you are actually on an @code{x86_64} machine:
4527 $ guix build --log-file gdb -s mips64el-linux
4528 https://hydra.gnu.org/log/@dots{}-gdb-7.10
4531 You can freely access a huge library of build logs!
4535 @node Invoking guix edit
4536 @section Invoking @command{guix edit}
4538 @cindex package definition, editing
4539 So many packages, so many source files! The @command{guix edit} command
4540 facilitates the life of users and packagers by pointing their editor at
4541 the source file containing the definition of the specified packages.
4545 guix edit gcc@@4.9 vim
4549 launches the program specified in the @code{VISUAL} or in the
4550 @code{EDITOR} environment variable to view the recipe of GCC@tie{}4.9.3
4553 If you are using a Guix Git checkout (@pxref{Building from Git}), or
4554 have created your own packages on @code{GUIX_PACKAGE_PATH}
4555 (@pxref{Defining Packages}), you will be able to edit the package
4556 recipes. Otherwise, you will be able to examine the read-only recipes
4557 for packages currently in the store.
4559 If you are using Emacs, note that the Emacs user interface provides the
4560 @kbd{M-x guix-edit} command and a similar functionality in the ``package
4561 info'' and ``package list'' buffers created by the @kbd{M-x
4562 guix-search-by-name} and similar commands (@pxref{Emacs Commands}).
4565 @node Invoking guix download
4566 @section Invoking @command{guix download}
4568 When writing a package definition, developers typically need to download
4569 a source tarball, compute its SHA256 hash, and write that
4570 hash in the package definition (@pxref{Defining Packages}). The
4571 @command{guix download} tool helps with this task: it downloads a file
4572 from the given URI, adds it to the store, and prints both its file name
4573 in the store and its SHA256 hash.
4575 The fact that the downloaded file is added to the store saves bandwidth:
4576 when the developer eventually tries to build the newly defined package
4577 with @command{guix build}, the source tarball will not have to be
4578 downloaded again because it is already in the store. It is also a
4579 convenient way to temporarily stash files, which may be deleted
4580 eventually (@pxref{Invoking guix gc}).
4582 The @command{guix download} command supports the same URIs as used in
4583 package definitions. In particular, it supports @code{mirror://} URIs.
4584 @code{https} URIs (HTTP over TLS) are supported @emph{provided} the
4585 Guile bindings for GnuTLS are available in the user's environment; when
4586 they are not available, an error is raised. @xref{Guile Preparations,
4587 how to install the GnuTLS bindings for Guile,, gnutls-guile,
4588 GnuTLS-Guile}, for more information.
4590 The following option is available:
4593 @item --format=@var{fmt}
4595 Write the hash in the format specified by @var{fmt}. For more
4596 information on the valid values for @var{fmt}, @pxref{Invoking guix hash}.
4599 @node Invoking guix hash
4600 @section Invoking @command{guix hash}
4602 The @command{guix hash} command computes the SHA256 hash of a file.
4603 It is primarily a convenience tool for anyone contributing to the
4604 distribution: it computes the cryptographic hash of a file, which can be
4605 used in the definition of a package (@pxref{Defining Packages}).
4607 The general syntax is:
4610 guix hash @var{option} @var{file}
4613 @command{guix hash} has the following option:
4617 @item --format=@var{fmt}
4619 Write the hash in the format specified by @var{fmt}.
4621 Supported formats: @code{nix-base32}, @code{base32}, @code{base16}
4622 (@code{hex} and @code{hexadecimal} can be used as well).
4624 If the @option{--format} option is not specified, @command{guix hash}
4625 will output the hash in @code{nix-base32}. This representation is used
4626 in the definitions of packages.
4630 Compute the hash on @var{file} recursively.
4632 In this case, the hash is computed on an archive containing @var{file},
4633 including its children if it is a directory. Some of the metadata of
4634 @var{file} is part of the archive; for instance, when @var{file} is a
4635 regular file, the hash is different depending on whether @var{file} is
4636 executable or not. Metadata such as time stamps has no impact on the
4637 hash (@pxref{Invoking guix archive}).
4638 @c FIXME: Replace xref above with xref to an ``Archive'' section when
4642 As an example, here is how you would compute the hash of a Git checkout,
4643 which is useful when using the @code{git-fetch} method (@pxref{origin
4647 $ git clone http://example.org/foo.git
4654 @node Invoking guix import
4655 @section Invoking @command{guix import}
4657 @cindex importing packages
4658 @cindex package import
4659 @cindex package conversion
4660 The @command{guix import} command is useful for people who would like to
4661 add a package to the distribution with as little work as
4662 possible---a legitimate demand. The command knows of a few
4663 repositories from which it can ``import'' package metadata. The result
4664 is a package definition, or a template thereof, in the format we know
4665 (@pxref{Defining Packages}).
4667 The general syntax is:
4670 guix import @var{importer} @var{options}@dots{}
4673 @var{importer} specifies the source from which to import package
4674 metadata, and @var{options} specifies a package identifier and other
4675 options specific to @var{importer}. Currently, the available
4680 Import metadata for the given GNU package. This provides a template
4681 for the latest version of that GNU package, including the hash of its
4682 source tarball, and its canonical synopsis and description.
4684 Additional information such as the package dependencies and its
4685 license needs to be figured out manually.
4687 For example, the following command returns a package definition for
4691 guix import gnu hello
4694 Specific command-line options are:
4697 @item --key-download=@var{policy}
4698 As for @code{guix refresh}, specify the policy to handle missing OpenPGP
4699 keys when verifying the package signature. @xref{Invoking guix
4700 refresh, @code{--key-download}}.
4705 Import metadata from the @uref{https://pypi.python.org/, Python Package
4706 Index}@footnote{This functionality requires Guile-JSON to be installed.
4707 @xref{Requirements}.}. Information is taken from the JSON-formatted
4708 description available at @code{pypi.python.org} and usually includes all
4709 the relevant information, including package dependencies. For maximum
4710 efficiency, it is recommended to install the @command{unzip} utility, so
4711 that the importer can unzip Python wheels and gather data from them.
4713 The command below imports metadata for the @code{itsdangerous} Python
4717 guix import pypi itsdangerous
4722 Import metadata from @uref{https://rubygems.org/,
4723 RubyGems}@footnote{This functionality requires Guile-JSON to be
4724 installed. @xref{Requirements}.}. Information is taken from the
4725 JSON-formatted description available at @code{rubygems.org} and includes
4726 most relevant information, including runtime dependencies. There are
4727 some caveats, however. The metadata doesn't distinguish between
4728 synopses and descriptions, so the same string is used for both fields.
4729 Additionally, the details of non-Ruby dependencies required to build
4730 native extensions is unavailable and left as an exercise to the
4733 The command below imports metadata for the @code{rails} Ruby package:
4736 guix import gem rails
4741 Import metadata from @uref{https://www.metacpan.org/, MetaCPAN}@footnote{This
4742 functionality requires Guile-JSON to be installed.
4743 @xref{Requirements}.}.
4744 Information is taken from the JSON-formatted metadata provided through
4745 @uref{https://api.metacpan.org/, MetaCPAN's API} and includes most
4746 relevant information, such as module dependencies. License information
4747 should be checked closely. If Perl is available in the store, then the
4748 @code{corelist} utility will be used to filter core modules out of the
4749 list of dependencies.
4751 The command command below imports metadata for the @code{Acme::Boolean}
4755 guix import cpan Acme::Boolean
4760 @cindex Bioconductor
4761 Import metadata from @uref{http://cran.r-project.org/, CRAN}, the
4762 central repository for the @uref{http://r-project.org, GNU@tie{}R
4763 statistical and graphical environment}.
4765 Information is extracted from the @code{DESCRIPTION} file of the package.
4767 The command command below imports metadata for the @code{Cairo}
4771 guix import cran Cairo
4774 When @code{--archive=bioconductor} is added, metadata is imported from
4775 @uref{http://www.bioconductor.org/, Bioconductor}, a repository of R
4776 packages for for the analysis and comprehension of high-throughput
4777 genomic data in bioinformatics.
4779 Information is extracted from the @code{DESCRIPTION} file of a package
4780 published on the web interface of the Bioconductor SVN repository.
4782 The command below imports metadata for the @code{GenomicRanges}
4786 guix import cran --archive=bioconductor GenomicRanges
4790 Import metadata from a local copy of the source of the
4791 @uref{http://nixos.org/nixpkgs/, Nixpkgs distribution}@footnote{This
4792 relies on the @command{nix-instantiate} command of
4793 @uref{http://nixos.org/nix/, Nix}.}. Package definitions in Nixpkgs are
4794 typically written in a mixture of Nix-language and Bash code. This
4795 command only imports the high-level package structure that is written in
4796 the Nix language. It normally includes all the basic fields of a
4799 When importing a GNU package, the synopsis and descriptions are replaced
4800 by their canonical upstream variant.
4802 Usually, you will first need to do:
4805 export NIX_REMOTE=daemon
4809 so that @command{nix-instantiate} does not try to open the Nix database.
4811 As an example, the command below imports the package definition of
4812 LibreOffice (more precisely, it imports the definition of the package
4813 bound to the @code{libreoffice} top-level attribute):
4816 guix import nix ~/path/to/nixpkgs libreoffice
4821 Import metadata from the Haskell community's central package archive
4822 @uref{https://hackage.haskell.org/, Hackage}. Information is taken from
4823 Cabal files and includes all the relevant information, including package
4826 Specific command-line options are:
4831 Read a Cabal file from standard input.
4832 @item --no-test-dependencies
4834 Do not include dependencies required only by the test suites.
4835 @item --cabal-environment=@var{alist}
4836 @itemx -e @var{alist}
4837 @var{alist} is a Scheme alist defining the environment in which the
4838 Cabal conditionals are evaluated. The accepted keys are: @code{os},
4839 @code{arch}, @code{impl} and a string representing the name of a flag.
4840 The value associated with a flag has to be either the symbol
4841 @code{true} or @code{false}. The value associated with other keys
4842 has to conform to the Cabal file format definition. The default value
4843 associated with the keys @code{os}, @code{arch} and @code{impl} is
4844 @samp{linux}, @samp{x86_64} and @samp{ghc}, respectively.
4847 The command below imports metadata for the latest version of the
4848 @code{HTTP} Haskell package without including test dependencies and
4849 specifying the value of the flag @samp{network-uri} as @code{false}:
4852 guix import hackage -t -e "'((\"network-uri\" . false))" HTTP
4855 A specific package version may optionally be specified by following the
4856 package name by an at-sign and a version number as in the following example:
4859 guix import hackage mtl@@2.1.3.1
4864 Import metadata from an Emacs Lisp Package Archive (ELPA) package
4865 repository (@pxref{Packages,,, emacs, The GNU Emacs Manual}).
4867 Specific command-line options are:
4870 @item --archive=@var{repo}
4871 @itemx -a @var{repo}
4872 @var{repo} identifies the archive repository from which to retrieve the
4873 information. Currently the supported repositories and their identifiers
4877 @uref{http://elpa.gnu.org/packages, GNU}, selected by the @code{gnu}
4878 identifier. This is the default.
4881 @uref{http://stable.melpa.org/packages, MELPA-Stable}, selected by the
4882 @code{melpa-stable} identifier.
4885 @uref{http://melpa.org/packages, MELPA}, selected by the @code{melpa}
4891 The structure of the @command{guix import} code is modular. It would be
4892 useful to have more importers for other package formats, and your help
4893 is welcome here (@pxref{Contributing}).
4895 @node Invoking guix refresh
4896 @section Invoking @command{guix refresh}
4898 The primary audience of the @command{guix refresh} command is developers
4899 of the GNU software distribution. By default, it reports any packages
4900 provided by the distribution that are outdated compared to the latest
4901 upstream version, like this:
4905 gnu/packages/gettext.scm:29:13: gettext would be upgraded from 0.18.1.1 to 0.18.2.1
4906 gnu/packages/glib.scm:77:12: glib would be upgraded from 2.34.3 to 2.37.0
4909 It does so by browsing the FTP directory of each package and determining
4910 the highest version number of the source tarballs therein. The command
4911 knows how to update specific types of packages: GNU packages, ELPA
4912 packages, etc.---see the documentation for @option{--type} below. The
4913 are many packages, though, for which it lacks a method to determine
4914 whether a new upstream release is available. However, the mechanism is
4915 extensible, so feel free to get in touch with us to add a new method!
4917 When passed @code{--update}, it modifies distribution source files to
4918 update the version numbers and source tarball hashes of those package
4919 recipes (@pxref{Defining Packages}). This is achieved by downloading
4920 each package's latest source tarball and its associated OpenPGP
4921 signature, authenticating the downloaded tarball against its signature
4922 using @command{gpg}, and finally computing its hash. When the public
4923 key used to sign the tarball is missing from the user's keyring, an
4924 attempt is made to automatically retrieve it from a public key server;
4925 when this is successful, the key is added to the user's keyring; otherwise,
4926 @command{guix refresh} reports an error.
4928 The following options are supported:
4932 @item --expression=@var{expr}
4933 @itemx -e @var{expr}
4934 Consider the package @var{expr} evaluates to.
4936 This is useful to precisely refer to a package, as in this example:
4939 guix refresh -l -e '(@@@@ (gnu packages commencement) glibc-final)'
4942 This command lists the dependents of the ``final'' libc (essentially all
4947 Update distribution source files (package recipes) in place. This is
4948 usually run from a checkout of the Guix source tree (@pxref{Running
4949 Guix Before It Is Installed}):
4952 $ ./pre-inst-env guix refresh -s non-core
4955 @xref{Defining Packages}, for more information on package definitions.
4957 @item --select=[@var{subset}]
4958 @itemx -s @var{subset}
4959 Select all the packages in @var{subset}, one of @code{core} or
4962 The @code{core} subset refers to all the packages at the core of the
4963 distribution---i.e., packages that are used to build ``everything
4964 else''. This includes GCC, libc, Binutils, Bash, etc. Usually,
4965 changing one of these packages in the distribution entails a rebuild of
4966 all the others. Thus, such updates are an inconvenience to users in
4967 terms of build time or bandwidth used to achieve the upgrade.
4969 The @code{non-core} subset refers to the remaining packages. It is
4970 typically useful in cases where an update of the core packages would be
4973 @item --type=@var{updater}
4974 @itemx -t @var{updater}
4975 Select only packages handled by @var{updater} (may be a comma-separated
4976 list of updaters). Currently, @var{updater} may be one of:
4980 the updater for GNU packages;
4982 the updater for GNOME packages;
4984 the updater for X.org packages;
4986 the updater for @uref{http://elpa.gnu.org/, ELPA} packages;
4988 the updater for @uref{http://cran.r-project.org/, CRAN} packages;
4990 the updater for @uref{http://www.bioconductor.org/, Bioconductor} R packages;
4992 the updater for @uref{https://pypi.python.org, PyPI} packages.
4994 the updater for @uref{https://rubygems.org, RubyGems} packages.
4996 the updater for @uref{https://github.com, GitHub} packages.
4998 the updater for @uref{https://hackage.haskell.org, Hackage} packages.
5001 For instance, the following command only checks for updates of Emacs
5002 packages hosted at @code{elpa.gnu.org} and for updates of CRAN packages:
5005 $ guix refresh --type=elpa,cran
5006 gnu/packages/statistics.scm:819:13: r-testthat would be upgraded from 0.10.0 to 0.11.0
5007 gnu/packages/emacs.scm:856:13: emacs-auctex would be upgraded from 11.88.6 to 11.88.9
5012 In addition, @command{guix refresh} can be passed one or more package
5013 names, as in this example:
5016 $ ./pre-inst-env guix refresh -u emacs idutils gcc-4.8.4
5020 The command above specifically updates the @code{emacs} and
5021 @code{idutils} packages. The @code{--select} option would have no
5022 effect in this case.
5024 When considering whether to upgrade a package, it is sometimes
5025 convenient to know which packages would be affected by the upgrade and
5026 should be checked for compatibility. For this the following option may
5027 be used when passing @command{guix refresh} one or more package names:
5031 @item --list-updaters
5033 List available updaters and exit (see @option{--type} above.)
5035 @item --list-dependent
5037 List top-level dependent packages that would need to be rebuilt as a
5038 result of upgrading one or more packages.
5042 Be aware that the @code{--list-dependent} option only
5043 @emph{approximates} the rebuilds that would be required as a result of
5044 an upgrade. More rebuilds might be required under some circumstances.
5047 $ guix refresh --list-dependent flex
5048 Building the following 120 packages would ensure 213 dependent packages are rebuilt:
5049 hop-2.4.0 geiser-0.4 notmuch-0.18 mu-0.9.9.5 cflow-1.4 idutils-4.6 @dots{}
5052 The command above lists a set of packages that could be built to check
5053 for compatibility with an upgraded @code{flex} package.
5055 The following options can be used to customize GnuPG operation:
5059 @item --gpg=@var{command}
5060 Use @var{command} as the GnuPG 2.x command. @var{command} is searched
5061 for in @code{$PATH}.
5063 @item --key-download=@var{policy}
5064 Handle missing OpenPGP keys according to @var{policy}, which may be one
5069 Always download missing OpenPGP keys from the key server, and add them
5070 to the user's GnuPG keyring.
5073 Never try to download missing OpenPGP keys. Instead just bail out.
5076 When a package signed with an unknown OpenPGP key is encountered, ask
5077 the user whether to download it or not. This is the default behavior.
5080 @item --key-server=@var{host}
5081 Use @var{host} as the OpenPGP key server when importing a public key.
5085 The @code{github} updater uses the
5086 @uref{https://developer.github.com/v3/, GitHub API} to query for new
5087 releases. When used repeatedly e.g. when refreshing all packages,
5088 GitHub will eventually refuse to answer any further API requests. By
5089 default 60 API requests per hour are allowed, and a full refresh on all
5090 GitHub packages in Guix requires more than this. Authentication with
5091 GitHub through the use of an API token alleviates these limits. To use
5092 an API token, set the environment variable @code{GUIX_GITHUB_TOKEN} to a
5093 token procured from @uref{https://github.com/settings/tokens} or
5097 @node Invoking guix lint
5098 @section Invoking @command{guix lint}
5099 The @command{guix lint} command is meant to help package developers avoid
5100 common errors and use a consistent style. It runs a number of checks on
5101 a given set of packages in order to find common mistakes in their
5102 definitions. Available @dfn{checkers} include (see
5103 @code{--list-checkers} for a complete list):
5108 Validate certain typographical and stylistic rules about package
5109 descriptions and synopses.
5111 @item inputs-should-be-native
5112 Identify inputs that should most likely be native inputs.
5116 @itemx source-file-name
5117 Probe @code{home-page} and @code{source} URLs and report those that are
5118 invalid. Check that the source file name is meaningful, e.g. is not
5119 just a version number or ``git-checkout'', without a declared
5120 @code{file-name} (@pxref{origin Reference}).
5123 @cindex security vulnerabilities
5124 @cindex CVE, Common Vulnerabilities and Exposures
5125 Report known vulnerabilities found in the Common Vulnerabilities and
5126 Exposures (CVE) databases of the current and past year
5127 @uref{https://nvd.nist.gov/download.cfm#CVE_FEED, published by the US
5130 To view information about a particular vulnerability, visit pages such as:
5134 @indicateurl{https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-YYYY-ABCD}
5136 @indicateurl{https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-YYYY-ABCD}
5140 where @code{CVE-YYYY-ABCD} is the CVE identifier---e.g.,
5141 @code{CVE-2015-7554}.
5143 Package developers can specify in package recipes the
5144 @uref{https://nvd.nist.gov/cpe.cfm,Common Platform Enumeration (CPE)}
5145 name and version of the package when they differ from the name that Guix
5146 uses, as in this example:
5152 ;; CPE calls this package "grub2".
5153 (properties '((cpe-name . "grub2"))))
5157 Warn about obvious source code formatting issues: trailing white space,
5158 use of tabulations, etc.
5161 The general syntax is:
5164 guix lint @var{options} @var{package}@dots{}
5167 If no package is given on the command line, then all packages are checked.
5168 The @var{options} may be zero or more of the following:
5171 @item --list-checkers
5173 List and describe all the available checkers that will be run on packages
5178 Only enable the checkers specified in a comma-separated list using the
5179 names returned by @code{--list-checkers}.
5183 @node Invoking guix size
5184 @section Invoking @command{guix size}
5186 The @command{guix size} command helps package developers profile the
5187 disk usage of packages. It is easy to overlook the impact of an
5188 additional dependency added to a package, or the impact of using a
5189 single output for a package that could easily be split (@pxref{Packages
5190 with Multiple Outputs}). Such are the typical issues that
5191 @command{guix size} can highlight.
5193 The command can be passed a package specification such as @code{gcc-4.8}
5194 or @code{guile:debug}, or a file name in the store. Consider this
5198 $ guix size coreutils
5199 store item total self
5200 /gnu/store/@dots{}-coreutils-8.23 70.0 13.9 19.8%
5201 /gnu/store/@dots{}-gmp-6.0.0a 55.3 2.5 3.6%
5202 /gnu/store/@dots{}-acl-2.2.52 53.7 0.5 0.7%
5203 /gnu/store/@dots{}-attr-2.4.46 53.2 0.3 0.5%
5204 /gnu/store/@dots{}-gcc-4.8.4-lib 52.9 15.7 22.4%
5205 /gnu/store/@dots{}-glibc-2.21 37.2 37.2 53.1%
5209 The store items listed here constitute the @dfn{transitive closure} of
5210 Coreutils---i.e., Coreutils and all its dependencies, recursively---as
5211 would be returned by:
5214 $ guix gc -R /gnu/store/@dots{}-coreutils-8.23
5217 Here the output shows three columns next to store items. The first column,
5218 labeled ``total'', shows the size in mebibytes (MiB) of the closure of
5219 the store item---that is, its own size plus the size of all its
5220 dependencies. The next column, labeled ``self'', shows the size of the
5221 item itself. The last column shows the ratio of the size of the item
5222 itself to the space occupied by all the items listed here.
5224 In this example, we see that the closure of Coreutils weighs in at
5225 70@tie{}MiB, half of which is taken by libc. (That libc represents a
5226 large fraction of the closure is not a problem @i{per se} because it is
5227 always available on the system anyway.)
5229 When the package passed to @command{guix size} is available in the
5230 store, @command{guix size} queries the daemon to determine its
5231 dependencies, and measures its size in the store, similar to @command{du
5232 -ms --apparent-size} (@pxref{du invocation,,, coreutils, GNU
5235 When the given package is @emph{not} in the store, @command{guix size}
5236 reports information based on the available substitutes
5237 (@pxref{Substitutes}). This makes it possible it to profile disk usage of
5238 store items that are not even on disk, only available remotely.
5240 You can also specify several package names:
5243 $ guix size coreutils grep sed bash
5244 store item total self
5245 /gnu/store/@dots{}-coreutils-8.24 77.8 13.8 13.4%
5246 /gnu/store/@dots{}-grep-2.22 73.1 0.8 0.8%
5247 /gnu/store/@dots{}-bash-4.3.42 72.3 4.7 4.6%
5248 /gnu/store/@dots{}-readline-6.3 67.6 1.2 1.2%
5254 In this example we see that the combination of the four packages takes
5255 102.3@tie{}MiB in total, which is much less than the sum of each closure
5256 since they have a lot of dependencies in common.
5258 The available options are:
5262 @item --substitute-urls=@var{urls}
5263 Use substitute information from @var{urls}.
5264 @xref{client-substitute-urls, the same option for @code{guix build}}.
5266 @item --map-file=@var{file}
5267 Write a graphical map of disk usage in PNG format to @var{file}.
5269 For the example above, the map looks like this:
5271 @image{images/coreutils-size-map,5in,, map of Coreutils disk usage
5272 produced by @command{guix size}}
5274 This option requires that
5275 @uref{http://wingolog.org/software/guile-charting/, Guile-Charting} be
5276 installed and visible in Guile's module search path. When that is not
5277 the case, @command{guix size} fails as it tries to load it.
5279 @item --system=@var{system}
5280 @itemx -s @var{system}
5281 Consider packages for @var{system}---e.g., @code{x86_64-linux}.
5285 @node Invoking guix graph
5286 @section Invoking @command{guix graph}
5289 Packages and their dependencies form a @dfn{graph}, specifically a
5290 directed acyclic graph (DAG). It can quickly become difficult to have a
5291 mental model of the package DAG, so the @command{guix graph} command
5292 provides a visual representation of the DAG. @command{guix graph}
5293 emits a DAG representation in the input format of
5294 @uref{http://www.graphviz.org/, Graphviz}, so its output can be passed
5295 directly to the @command{dot} command of Graphviz. The general
5299 guix graph @var{options} @var{package}@dots{}
5302 For example, the following command generates a PDF file representing the
5303 package DAG for the GNU@tie{}Core Utilities, showing its build-time
5307 guix graph coreutils | dot -Tpdf > dag.pdf
5310 The output looks like this:
5312 @image{images/coreutils-graph,2in,,Dependency graph of the GNU Coreutils}
5314 Nice little graph, no?
5316 But there is more than one graph! The one above is concise: it is the
5317 graph of package objects, omitting implicit inputs such as GCC, libc,
5318 grep, etc. It is often useful to have such a concise graph, but
5319 sometimes one may want to see more details. @command{guix graph} supports
5320 several types of graphs, allowing you to choose the level of detail:
5324 This is the default type used in the example above. It shows the DAG of
5325 package objects, excluding implicit dependencies. It is concise, but
5326 filters out many details.
5329 This is the package DAG, @emph{including} implicit inputs.
5331 For instance, the following command:
5334 guix graph --type=bag-emerged coreutils | dot -Tpdf > dag.pdf
5337 ... yields this bigger graph:
5339 @image{images/coreutils-bag-graph,,5in,Detailed dependency graph of the GNU Coreutils}
5341 At the bottom of the graph, we see all the implicit inputs of
5342 @var{gnu-build-system} (@pxref{Build Systems, @code{gnu-build-system}}).
5344 Now, note that the dependencies of these implicit inputs---that is, the
5345 @dfn{bootstrap dependencies} (@pxref{Bootstrapping})---are not shown
5346 here, for conciseness.
5349 Similar to @code{bag-emerged}, but this time including all the bootstrap
5352 @item bag-with-origins
5353 Similar to @code{bag}, but also showing origins and their dependencies.
5356 This is the most detailed representation: It shows the DAG of
5357 derivations (@pxref{Derivations}) and plain store items. Compared to
5358 the above representation, many additional nodes are visible, including
5359 build scripts, patches, Guile modules, etc.
5361 For this type of graph, it is also possible to pass a @file{.drv} file
5362 name instead of a package name, as in:
5365 guix graph -t derivation `guix system build -d my-config.scm`
5369 All the types above correspond to @emph{build-time dependencies}. The
5370 following graph type represents the @emph{run-time dependencies}:
5374 This is the graph of @dfn{references} of a package output, as returned
5375 by @command{guix gc --references} (@pxref{Invoking guix gc}).
5377 If the given package output is not available in the store, @command{guix
5378 graph} attempts to obtain dependency information from substitutes.
5380 Here you can also pass a store file name instead of a package name. For
5381 example, the command below produces the reference graph of your profile
5382 (which can be big!):
5385 guix graph -t references `readlink -f ~/.guix-profile`
5389 The available options are the following:
5392 @item --type=@var{type}
5393 @itemx -t @var{type}
5394 Produce a graph output of @var{type}, where @var{type} must be one of
5395 the values listed above.
5398 List the supported graph types.
5400 @item --expression=@var{expr}
5401 @itemx -e @var{expr}
5402 Consider the package @var{expr} evaluates to.
5404 This is useful to precisely refer to a package, as in this example:
5407 guix graph -e '(@@@@ (gnu packages commencement) gnu-make-final)'
5412 @node Invoking guix environment
5413 @section Invoking @command{guix environment}
5415 @cindex reproducible build environments
5416 @cindex development environments
5417 The purpose of @command{guix environment} is to assist hackers in
5418 creating reproducible development environments without polluting their
5419 package profile. The @command{guix environment} tool takes one or more
5420 packages, builds all of their inputs, and creates a shell
5421 environment to use them.
5423 The general syntax is:
5426 guix environment @var{options} @var{package}@dots{}
5429 The following example spawns a new shell set up for the development of
5433 guix environment guile
5436 If the needed dependencies are not built yet, @command{guix environment}
5437 automatically builds them. The environment of the new shell is an augmented
5438 version of the environment that @command{guix environment} was run in.
5439 It contains the necessary search paths for building the given package
5440 added to the existing environment variables. To create a ``pure''
5441 environment, in which the original environment variables have been unset,
5442 use the @code{--pure} option@footnote{Users sometimes wrongfully augment
5443 environment variables such as @code{PATH} in their @file{~/.bashrc}
5444 file. As a consequence, when @code{guix environment} launches it, Bash
5445 may read @file{~/.bashrc}, thereby introducing ``impurities'' in these
5446 environment variables. It is an error to define such environment
5447 variables in @file{.bashrc}; instead, they should be defined in
5448 @file{.bash_profile}, which is sourced only by log-in shells.
5449 @xref{Bash Startup Files,,, bash, The GNU Bash Reference Manual}, for
5450 details on Bash start-up files.}.
5452 @vindex GUIX_ENVIRONMENT
5453 @command{guix environment} defines the @code{GUIX_ENVIRONMENT}
5454 variable in the shell it spawns. This allows users to, say, define a
5455 specific prompt for development environments in their @file{.bashrc}
5456 (@pxref{Bash Startup Files,,, bash, The GNU Bash Reference Manual}):
5459 if [ -n "$GUIX_ENVIRONMENT" ]
5461 export PS1="\u@@\h \w [dev]\$ "
5465 Additionally, more than one package may be specified, in which case the
5466 union of the inputs for the given packages are used. For example, the
5467 command below spawns a shell where all of the dependencies of both Guile
5468 and Emacs are available:
5471 guix environment guile emacs
5474 Sometimes an interactive shell session is not desired. An arbitrary
5475 command may be invoked by placing the @code{--} token to separate the
5476 command from the rest of the arguments:
5479 guix environment guile -- make -j4
5482 In other situations, it is more convenient to specify the list of
5483 packages needed in the environment. For example, the following command
5484 runs @command{python} from an environment containing Python@tie{}2.7 and
5488 guix environment --ad-hoc python2-numpy python-2.7 -- python
5491 Furthermore, one might want the dependencies of a package and also some
5492 additional packages that are not build-time or runtime dependencies, but
5493 are useful when developing nonetheless. Because of this, the
5494 @code{--ad-hoc} flag is positional. Packages appearing before
5495 @code{--ad-hoc} are interpreted as packages whose dependencies will be
5496 added to the environment. Packages appearing after are interpreted as
5497 packages that will be added to the environment directly. For example,
5498 the following command creates a Guix development environment that
5499 additionally includes Git and strace:
5502 guix environment guix --ad-hoc git strace
5505 Sometimes it is desirable to isolate the environment as much as
5506 possible, for maximal purity and reproducibility. In particular, when
5507 using Guix on a host distro that is not GuixSD, it is desirable to
5508 prevent access to @file{/usr/bin} and other system-wide resources from
5509 the development environment. For example, the following command spawns
5510 a Guile REPL in a ``container'' where only the store and the current
5511 working directory are mounted:
5514 guix environment --ad-hoc --container guile -- guile
5518 The @code{--container} option requires Linux-libre 3.19 or newer.
5521 The available options are summarized below.
5524 @item --expression=@var{expr}
5525 @itemx -e @var{expr}
5526 Create an environment for the package or list of packages that
5527 @var{expr} evaluates to.
5529 For example, running:
5532 guix environment -e '(@@ (gnu packages maths) petsc-openmpi)'
5535 starts a shell with the environment for this specific variant of the
5541 guix environment --ad-hoc -e '(@@ (gnu) %base-packages)'
5544 starts a shell with all the GuixSD base packages available.
5546 The above commands only the use default output of the given packages.
5547 To select other outputs, two element tuples can be specified:
5550 guix environment --ad-hoc -e '(list (@ (gnu packages bash) bash) "include")'
5553 @item --load=@var{file}
5554 @itemx -l @var{file}
5555 Create an environment for the package or list of packages that the code
5556 within @var{file} evaluates to.
5558 As an example, @var{file} might contain a definition like this
5559 (@pxref{Defining Packages}):
5562 @verbatiminclude environment-gdb.scm
5566 Include all specified packages in the resulting environment, as if an
5567 @i{ad hoc} package were defined with them as inputs. This option is
5568 useful for quickly creating an environment without having to write a
5569 package expression to contain the desired inputs.
5571 For instance, the command:
5574 guix environment --ad-hoc guile guile-sdl -- guile
5577 runs @command{guile} in an environment where Guile and Guile-SDL are
5580 Note that this example implicitly asks for the default output of
5581 @code{guile} and @code{guile-sdl}, but it is possible to ask for a
5582 specific output---e.g., @code{glib:bin} asks for the @code{bin} output
5583 of @code{glib} (@pxref{Packages with Multiple Outputs}).
5585 This option may be composed with the default behavior of @command{guix
5586 environment}. Packages appearing before @code{--ad-hoc} are interpreted
5587 as packages whose dependencies will be added to the environment, the
5588 default behavior. Packages appearing after are interpreted as packages
5589 that will be added to the environment directly.
5592 Unset existing environment variables when building the new environment.
5593 This has the effect of creating an environment in which search paths
5594 only contain package inputs.
5596 @item --search-paths
5597 Display the environment variable definitions that make up the
5600 @item --system=@var{system}
5601 @itemx -s @var{system}
5602 Attempt to build for @var{system}---e.g., @code{i686-linux}.
5607 Run @var{command} within an isolated container. The current working
5608 directory outside the container is mapped inside the container.
5609 Additionally, a dummy home directory is created that matches the current
5610 user's home directory, and @file{/etc/passwd} is configured accordingly.
5611 The spawned process runs as the current user outside the container, but
5612 has root privileges in the context of the container.
5616 For containers, share the network namespace with the host system.
5617 Containers created without this flag only have access to the loopback
5620 @item --expose=@var{source}[=@var{target}]
5621 For containers, expose the file system @var{source} from the host system
5622 as the read-only file system @var{target} within the container. If
5623 @var{target} is not specified, @var{source} is used as the target mount
5624 point in the container.
5626 The example below spawns a Guile REPL in a container in which the user's
5627 home directory is accessible read-only via the @file{/exchange}
5631 guix environment --container --expose=$HOME=/exchange guile -- guile
5634 @item --share=@var{source}[=@var{target}]
5635 For containers, share the file system @var{source} from the host system
5636 as the writable file system @var{target} within the container. If
5637 @var{target} is not specified, @var{source} is used as the target mount
5638 point in the container.
5640 The example below spawns a Guile REPL in a container in which the user's
5641 home directory is accessible for both reading and writing via the
5642 @file{/exchange} directory:
5645 guix environment --container --share=$HOME=/exchange guile -- guile
5649 It also supports all of the common build options that @command{guix
5650 build} supports (@pxref{Common Build Options}).
5652 @node Invoking guix publish
5653 @section Invoking @command{guix publish}
5655 The purpose of @command{guix publish} is to enable users to easily share
5656 their store with others, who can then use it as a substitute server
5657 (@pxref{Substitutes}).
5659 When @command{guix publish} runs, it spawns an HTTP server which allows
5660 anyone with network access to obtain substitutes from it. This means
5661 that any machine running Guix can also act as if it were a build farm,
5662 since the HTTP interface is compatible with Hydra, the software behind
5663 the @code{hydra.gnu.org} build farm.
5665 For security, each substitute is signed, allowing recipients to check
5666 their authenticity and integrity (@pxref{Substitutes}). Because
5667 @command{guix publish} uses the signing key of the system, which is only
5668 readable by the system administrator, it must be started as root; the
5669 @code{--user} option makes it drop root privileges early on.
5671 The signing key pair must be generated before @command{guix publish} is
5672 launched, using @command{guix archive --generate-key} (@pxref{Invoking
5675 The general syntax is:
5678 guix publish @var{options}@dots{}
5681 Running @command{guix publish} without any additional arguments will
5682 spawn an HTTP server on port 8080:
5688 Once a publishing server has been authorized (@pxref{Invoking guix
5689 archive}), the daemon may download substitutes from it:
5692 guix-daemon --substitute-urls=http://example.org:8080
5695 As a bonus, @command{guix publish} also serves as a content-addressed
5696 mirror for source files referenced in @code{origin} records
5697 (@pxref{origin Reference}). For instance, assuming @command{guix
5698 publish} is running on @code{example.org}, the following URL returns the
5699 raw @file{hello-2.10.tar.gz} file with the given SHA256 hash
5700 (represented in @code{nix-base32} format, @pxref{Invoking guix hash}):
5703 http://example.org/file/hello-2.10.tar.gz/sha256/0ssi1@dots{}ndq1i
5706 Obviously, these URLs only work for files that are in the store; in
5707 other cases, they return 404 (``Not Found'').
5709 The following options are available:
5712 @item --port=@var{port}
5713 @itemx -p @var{port}
5714 Listen for HTTP requests on @var{port}.
5716 @item --listen=@var{host}
5717 Listen on the network interface for @var{host}. The default is to
5718 accept connections from any interface.
5720 @item --user=@var{user}
5721 @itemx -u @var{user}
5722 Change privileges to @var{user} as soon as possible---i.e., once the
5723 server socket is open and the signing key has been read.
5725 @item --compression[=@var{level}]
5726 @itemx -C [@var{level}]
5727 Compress data using the given @var{level}. When @var{level} is zero,
5728 disable compression. The range 1 to 9 corresponds to different gzip
5729 compression levels: 1 is the fastest, and 9 is the best (CPU-intensive).
5732 Compression occurs on the fly and the compressed streams are not
5733 cached. Thus, to reduce load on the machine that runs @command{guix
5734 publish}, it may be a good idea to choose a low compression level, or to
5735 run @command{guix publish} behind a caching proxy.
5737 @item --ttl=@var{ttl}
5738 Produce @code{Cache-Control} HTTP headers that advertise a time-to-live
5739 (TTL) of @var{ttl}. @var{ttl} must denote a duration: @code{5d} means 5
5740 days, @code{1m} means 1 month, and so on.
5742 This allows the user's Guix to keep substitute information in cache for
5743 @var{ttl}. However, note that @code{guix publish} does not itself
5744 guarantee that the store items it provides will indeed remain available
5745 for as long as @var{ttl}.
5747 @item --repl[=@var{port}]
5748 @itemx -r [@var{port}]
5749 Spawn a Guile REPL server (@pxref{REPL Servers,,, guile, GNU Guile
5750 Reference Manual}) on @var{port} (37146 by default). This is used
5751 primarily for debugging a running @command{guix publish} server.
5754 Enabling @command{guix publish} on a GuixSD system is a one-liner: just
5755 add a call to @code{guix-publish-service} in the @code{services} field
5756 of the @code{operating-system} declaration (@pxref{guix-publish-service,
5757 @code{guix-publish-service}}).
5760 @node Invoking guix challenge
5761 @section Invoking @command{guix challenge}
5763 @cindex reproducible builds
5764 @cindex verifiable builds
5766 Do the binaries provided by this server really correspond to the source
5767 code it claims to build? Is a package build process deterministic?
5768 These are the questions the @command{guix challenge} command attempts to
5771 The former is obviously an important question: Before using a substitute
5772 server (@pxref{Substitutes}), one had better @emph{verify} that it
5773 provides the right binaries, and thus @emph{challenge} it. The latter
5774 is what enables the former: If package builds are deterministic, then
5775 independent builds of the package should yield the exact same result,
5776 bit for bit; if a server provides a binary different from the one
5777 obtained locally, it may be either corrupt or malicious.
5779 We know that the hash that shows up in @file{/gnu/store} file names is
5780 the hash of all the inputs of the process that built the file or
5781 directory---compilers, libraries, build scripts,
5782 etc. (@pxref{Introduction}). Assuming deterministic build processes,
5783 one store file name should map to exactly one build output.
5784 @command{guix challenge} checks whether there is, indeed, a single
5785 mapping by comparing the build outputs of several independent builds of
5786 any given store item.
5788 The command output looks like this:
5791 $ guix challenge --substitute-urls="https://hydra.gnu.org https://guix.example.org"
5792 updating list of substitutes from 'https://hydra.gnu.org'... 100.0%
5793 updating list of substitutes from 'https://guix.example.org'... 100.0%
5794 /gnu/store/@dots{}-openssl-1.0.2d contents differ:
5795 local hash: 0725l22r5jnzazaacncwsvp9kgf42266ayyp814v7djxs7nk963q
5796 https://hydra.gnu.org/nar/@dots{}-openssl-1.0.2d: 0725l22r5jnzazaacncwsvp9kgf42266ayyp814v7djxs7nk963q
5797 https://guix.example.org/nar/@dots{}-openssl-1.0.2d: 1zy4fmaaqcnjrzzajkdn3f5gmjk754b43qkq47llbyak9z0qjyim
5798 /gnu/store/@dots{}-git-2.5.0 contents differ:
5799 local hash: 00p3bmryhjxrhpn2gxs2fy0a15lnip05l97205pgbk5ra395hyha
5800 https://hydra.gnu.org/nar/@dots{}-git-2.5.0: 069nb85bv4d4a6slrwjdy8v1cn4cwspm3kdbmyb81d6zckj3nq9f
5801 https://guix.example.org/nar/@dots{}-git-2.5.0: 0mdqa9w1p6cmli6976v4wi0sw9r4p5prkj7lzfd1877wk11c9c73
5802 /gnu/store/@dots{}-pius-2.1.1 contents differ:
5803 local hash: 0k4v3m9z1zp8xzzizb7d8kjj72f9172xv078sq4wl73vnq9ig3ax
5804 https://hydra.gnu.org/nar/@dots{}-pius-2.1.1: 0k4v3m9z1zp8xzzizb7d8kjj72f9172xv078sq4wl73vnq9ig3ax
5805 https://guix.example.org/nar/@dots{}-pius-2.1.1: 1cy25x1a4fzq5rk0pmvc8xhwyffnqz95h2bpvqsz2mpvlbccy0gs
5809 In this example, @command{guix challenge} first scans the store to
5810 determine the set of locally-built derivations---as opposed to store
5811 items that were downloaded from a substitute server---and then queries
5812 all the substitute servers. It then reports those store items for which
5813 the servers obtained a result different from the local build.
5815 @cindex non-determinism, in package builds
5816 As an example, @code{guix.example.org} always gets a different answer.
5817 Conversely, @code{hydra.gnu.org} agrees with local builds, except in the
5818 case of Git. This might indicate that the build process of Git is
5819 non-deterministic, meaning that its output varies as a function of
5820 various things that Guix does not fully control, in spite of building
5821 packages in isolated environments (@pxref{Features}). Most common
5822 sources of non-determinism include the addition of timestamps in build
5823 results, the inclusion of random numbers, and directory listings sorted
5824 by inode number. See @uref{https://reproducible-builds.org/docs/}, for
5827 To find out what is wrong with this Git binary, we can do something along
5828 these lines (@pxref{Invoking guix archive}):
5831 $ wget -q -O - https://hydra.gnu.org/nar/@dots{}-git-2.5.0 \
5832 | guix archive -x /tmp/git
5833 $ diff -ur --no-dereference /gnu/store/@dots{}-git.2.5.0 /tmp/git
5836 This command shows the difference between the files resulting from the
5837 local build, and the files resulting from the build on
5838 @code{hydra.gnu.org} (@pxref{Overview, Comparing and Merging Files,,
5839 diffutils, Comparing and Merging Files}). The @command{diff} command
5840 works great for text files. When binary files differ, a better option
5841 is @uref{https://diffoscope.org/, Diffoscope}, a tool that helps
5842 visualize differences for all kinds of files.
5844 Once you have done that work, you can tell whether the differences are due
5845 to a non-deterministic build process or to a malicious server. We try
5846 hard to remove sources of non-determinism in packages to make it easier
5847 to verify substitutes, but of course, this is a process that
5848 involves not just Guix, but a large part of the free software community.
5849 In the meantime, @command{guix challenge} is one tool to help address
5852 If you are writing packages for Guix, you are encouraged to check
5853 whether @code{hydra.gnu.org} and other substitute servers obtain the
5854 same build result as you did with:
5857 $ guix challenge @var{package}
5861 where @var{package} is a package specification such as
5862 @code{guile@@2.0} or @code{glibc:debug}.
5864 The general syntax is:
5867 guix challenge @var{options} [@var{packages}@dots{}]
5870 When a difference is found between the hash of a locally-built item and
5871 that of a server-provided substitute, or among substitutes provided by
5872 different servers, the command displays it as in the example above and
5873 its exit code is 2 (other non-zero exit codes denote other kinds of
5876 The one option that matters is:
5880 @item --substitute-urls=@var{urls}
5881 Consider @var{urls} the whitespace-separated list of substitute source
5887 @node Invoking guix container
5888 @section Invoking @command{guix container}
5892 As of version @value{VERSION}, this tool is experimental. The interface
5893 is subject to radical change in the future.
5896 The purpose of @command{guix container} is to manipulate processes
5897 running within an isolated environment, commonly known as a
5898 ``container'', typically created by the @command{guix environment}
5899 (@pxref{Invoking guix environment}) and @command{guix system container}
5900 (@pxref{Invoking guix system}) commands.
5902 The general syntax is:
5905 guix container @var{action} @var{options}@dots{}
5908 @var{action} specifies the operation to perform with a container, and
5909 @var{options} specifies the context-specific arguments for the action.
5911 The following actions are available:
5915 Execute a command within the context of a running container.
5920 guix container exec @var{pid} @var{program} @var{arguments}@dots{}
5923 @var{pid} specifies the process ID of the running container.
5924 @var{program} specifies an executable file name within the root file
5925 system of the container. @var{arguments} are the additional options that
5926 will be passed to @var{program}.
5928 The following command launches an interactive login shell inside a
5929 GuixSD container, started by @command{guix system container}, and whose
5933 guix container exec 9001 /run/current-system/profile/bin/bash --login
5936 Note that the @var{pid} cannot be the parent process of a container. It
5937 must be PID 1 of the container or one of its child processes.
5941 @c *********************************************************************
5942 @node GNU Distribution
5943 @chapter GNU Distribution
5945 @cindex Guix System Distribution
5947 Guix comes with a distribution of the GNU system consisting entirely of
5948 free software@footnote{The term ``free'' here refers to the
5949 @url{http://www.gnu.org/philosophy/free-sw.html,freedom provided to
5950 users of that software}.}. The
5951 distribution can be installed on its own (@pxref{System Installation}),
5952 but it is also possible to install Guix as a package manager on top of
5953 an installed GNU/Linux system (@pxref{Installation}). To distinguish
5954 between the two, we refer to the standalone distribution as the Guix
5955 System Distribution, or GuixSD.
5957 The distribution provides core GNU packages such as GNU libc, GCC, and
5958 Binutils, as well as many GNU and non-GNU applications. The complete
5959 list of available packages can be browsed
5960 @url{http://www.gnu.org/software/guix/packages,on-line} or by
5961 running @command{guix package} (@pxref{Invoking guix package}):
5964 guix package --list-available
5967 Our goal is to provide a practical 100% free software distribution of
5968 Linux-based and other variants of GNU, with a focus on the promotion and
5969 tight integration of GNU components, and an emphasis on programs and
5970 tools that help users exert that freedom.
5972 Packages are currently available on the following platforms:
5977 Intel/AMD @code{x86_64} architecture, Linux-Libre kernel;
5980 Intel 32-bit architecture (IA32), Linux-Libre kernel;
5983 ARMv7-A architecture with hard float, Thumb-2 and NEON,
5984 using the EABI hard-float application binary interface (ABI),
5985 and Linux-Libre kernel.
5987 @item mips64el-linux
5988 little-endian 64-bit MIPS processors, specifically the Loongson series,
5989 n32 ABI, and Linux-Libre kernel.
5993 GuixSD itself is currently only available on @code{i686} and @code{x86_64}.
5996 For information on porting to other architectures or kernels,
6000 * System Installation:: Installing the whole operating system.
6001 * System Configuration:: Configuring the operating system.
6002 * Installing Debugging Files:: Feeding the debugger.
6003 * Security Updates:: Deploying security fixes quickly.
6004 * Package Modules:: Packages from the programmer's viewpoint.
6005 * Packaging Guidelines:: Growing the distribution.
6006 * Bootstrapping:: GNU/Linux built from scratch.
6007 * Porting:: Targeting another platform or kernel.
6010 Building this distribution is a cooperative effort, and you are invited
6011 to join! @xref{Contributing}, for information about how you can help.
6013 @node System Installation
6014 @section System Installation
6016 @cindex Guix System Distribution
6017 This section explains how to install the Guix System Distribution
6018 on a machine. The Guix package manager can
6019 also be installed on top of a running GNU/Linux system,
6020 @pxref{Installation}.
6024 @c This paragraph is for people reading this from tty2 of the
6025 @c installation image.
6026 You are reading this documentation with an Info reader. For details on
6027 how to use it, hit the @key{RET} key (``return'' or ``enter'') on the
6028 link that follows: @pxref{Top, Info reader,, info-stnd, Stand-alone GNU
6029 Info}. Hit @kbd{l} afterwards to come back here.
6031 Alternately, run @command{info info} in another tty to keep the manual
6037 * Limitations:: What you can expect.
6038 * Hardware Considerations:: Supported hardware.
6039 * USB Stick Installation:: Preparing the installation medium.
6040 * Preparing for Installation:: Networking, partitioning, etc.
6041 * Proceeding with the Installation:: The real thing.
6042 * Building the Installation Image:: How this comes to be.
6046 @subsection Limitations
6048 As of version @value{VERSION}, the Guix System Distribution (GuixSD) is
6049 not production-ready. It may contain bugs and lack important
6050 features. Thus, if you are looking for a stable production system that
6051 respects your freedom as a computer user, a good solution at this point
6052 is to consider @url{http://www.gnu.org/distros/free-distros.html, one of
6053 the more established GNU/Linux distributions}. We hope you can soon switch
6054 to the GuixSD without fear, of course. In the meantime, you can
6055 also keep using your distribution and try out the package manager on top
6056 of it (@pxref{Installation}).
6058 Before you proceed with the installation, be aware of the following
6059 noteworthy limitations applicable to version @value{VERSION}:
6063 The installation process does not include a graphical user interface and
6064 requires familiarity with GNU/Linux (see the following subsections to
6065 get a feel of what that means.)
6068 Support for the Logical Volume Manager (LVM) is missing.
6071 Few system services are currently supported out-of-the-box
6075 More than 3,200 packages are available, but you may
6076 occasionally find that a useful package is missing.
6079 GNOME, Xfce, and Enlightenment are available (@pxref{Desktop Services}),
6080 as well as a number of X11 window managers. However, some graphical
6081 applications may be missing, as well as KDE.
6084 You have been warned! But more than a disclaimer, this is an invitation
6085 to report issues (and success stories!), and to join us in improving it.
6086 @xref{Contributing}, for more info.
6089 @node Hardware Considerations
6090 @subsection Hardware Considerations
6092 @cindex hardware support on GuixSD
6093 GNU@tie{}GuixSD focuses on respecting the user's computing freedom. It
6094 builds around the kernel Linux-libre, which means that only hardware for
6095 which free software drivers and firmware exist is supported. Nowadays,
6096 a wide range of off-the-shelf hardware is supported on
6097 GNU/Linux-libre---from keyboards to graphics cards to scanners and
6098 Ethernet controllers. Unfortunately, there are still areas where
6099 hardware vendors deny users control over their own computing, and such
6100 hardware is not supported on GuixSD.
6102 @cindex WiFi, hardware support
6103 One of the main areas where free drivers or firmware are lacking is WiFi
6104 devices. WiFi devices known to work include those using Atheros chips
6105 (AR9271 and AR7010), which corresponds to the @code{ath9k} Linux-libre
6106 driver, and for which free firmware exists and is available
6107 out-of-the-box on GuixSD, as part of @var{%base-firmware}
6108 (@pxref{operating-system Reference, @code{firmware}}).
6110 @cindex RYF, Respects Your Freedom
6111 The @uref{https://www.fsf.org/, Free Software Foundation} runs
6112 @uref{https://www.fsf.org/ryf, @dfn{Respects Your Freedom}} (RYF), a
6113 certification program for hardware products that respect your freedom
6114 and your privacy and ensure that you have control over your device. We
6115 encourage you to check the list of RYF-certified devices.
6117 Another useful resource is the @uref{https://www.h-node.org/, H-Node}
6118 web site. It contains a catalog of hardware devices with information
6119 about their support in GNU/Linux.
6122 @node USB Stick Installation
6123 @subsection USB Stick Installation
6125 An installation image for USB sticks can be downloaded from
6126 @indicateurl{ftp://alpha.gnu.org/gnu/guix/guixsd-usb-install-@value{VERSION}.@var{system}.xz},
6127 where @var{system} is one of:
6131 for a GNU/Linux system on Intel/AMD-compatible 64-bit CPUs;
6134 for a 32-bit GNU/Linux system on Intel-compatible CPUs.
6137 This image contains a single partition with the tools necessary for an
6138 installation. It is meant to be copied @emph{as is} to a large-enough
6141 To copy the image to a USB stick, follow these steps:
6145 Decompress the image using the @command{xz} command:
6148 xz -d guixsd-usb-install-@value{VERSION}.@var{system}.xz
6152 Insert a USB stick of 1@tie{}GiB or more into your machine, and determine
6153 its device name. Assuming that the USB stick is known as @file{/dev/sdX},
6154 copy the image with:
6157 dd if=guixsd-usb-install-@value{VERSION}.x86_64 of=/dev/sdX
6160 Access to @file{/dev/sdX} usually requires root privileges.
6163 Once this is done, you should be able to reboot the system and boot from
6164 the USB stick. The latter usually requires you to get in the BIOS' boot
6165 menu, where you can choose to boot from the USB stick.
6167 @node Preparing for Installation
6168 @subsection Preparing for Installation
6170 Once you have successfully booted the image on the USB stick, you should
6171 end up with a root prompt. Several console TTYs are configured and can
6172 be used to run commands as root. TTY2 shows this documentation,
6173 browsable using the Info reader commands (@pxref{Top,,, info-stnd,
6174 Stand-alone GNU Info}). The installation system runs the GPM mouse
6175 daemon, which allows you to select text with the left mouse button and
6176 to paste it with the middle button.
6179 Installation requires access to the Internet so that any missing
6180 dependencies of your system configuration can be downloaded. See the
6181 ``Networking'' section below.
6184 The installation system includes many common tools needed for this task.
6185 But it is also a full-blown GuixSD system, which means that you can
6186 install additional packages, should you need it, using @command{guix
6187 package} (@pxref{Invoking guix package}).
6189 @subsubsection Keyboard Layout
6191 @cindex keyboard layout
6192 The installation image uses the US qwerty keyboard layout. If you want
6193 to change it, you can use the @command{loadkeys} command. For example,
6194 the following command selects the Dvorak keyboard layout:
6200 See the files under @file{/run/current-system/profile/share/keymaps} for
6201 a list of available keyboard layouts. Run @command{man loadkeys} for
6204 @subsubsection Networking
6206 Run the following command see what your network interfaces are called:
6213 @dots{} or, using the GNU/Linux-specific @command{ip} command:
6219 @c http://cgit.freedesktop.org/systemd/systemd/tree/src/udev/udev-builtin-net_id.c#n20
6220 Wired interfaces have a name starting with @samp{e}; for example, the
6221 interface corresponding to the first on-board Ethernet controller is
6222 called @samp{eno1}. Wireless interfaces have a name starting with
6223 @samp{w}, like @samp{w1p2s0}.
6226 @item Wired connection
6227 To configure a wired network run the following command, substituting
6228 @var{interface} with the name of the wired interface you want to use.
6231 ifconfig @var{interface} up
6234 @item Wireless connection
6235 To configure wireless networking, you can create a configuration file
6236 for the @command{wpa_supplicant} configuration tool (its location is not
6237 important) using one of the available text editors such as
6241 zile wpa_supplicant.conf
6244 As an example, the following stanza can go to this file and will work
6245 for many wireless networks, provided you give the actual SSID and
6246 passphrase for the network you are connecting to:
6250 ssid="@var{my-ssid}"
6252 psk="the network's secret passphrase"
6256 Start the wireless service and run it in the background with the
6257 following command (substitute @var{interface} with the name of the
6258 network interface you want to use):
6261 wpa_supplicant -c wpa_supplicant.conf -i @var{interface} -B
6264 Run @command{man wpa_supplicant} for more information.
6267 At this point, you need to acquire an IP address. On a network where IP
6268 addresses are automatically assigned @i{via} DHCP, you can run:
6271 dhclient -v @var{interface}
6274 Try to ping a server to see if networking is up and running:
6280 Setting up network access is almost always a requirement because the
6281 image does not contain all the software and tools that may be needed.
6283 @subsubsection Disk Partitioning
6285 Unless this has already been done, the next step is to partition, and
6286 then format the target partition(s).
6288 The installation image includes several partitioning tools, including
6289 Parted (@pxref{Overview,,, parted, GNU Parted User Manual}),
6290 @command{fdisk}, and @command{cfdisk}. Run it and set up your disk with
6291 the partition layout you want:
6297 Once you are done partitioning the target hard disk drive, you have to
6298 create a file system on the relevant partition(s)@footnote{Currently
6299 GuixSD pretty much assumes an ext4 file system. In particular, code
6300 that reads partition UUIDs and labels only works with ext4. This will
6301 be fixed in the future.}.
6303 Preferably, assign partitions a label so that you can easily and
6304 reliably refer to them in @code{file-system} declarations (@pxref{File
6305 Systems}). This is typically done using the @code{-L} option of
6306 @command{mkfs.ext4} and related commands. So, assuming the target root
6307 partition lives at @file{/dev/sda1}, a file system with the label
6308 @code{my-root} can be created with:
6311 mkfs.ext4 -L my-root /dev/sda1
6314 @c FIXME: Uncomment this once GRUB fully supports encrypted roots.
6315 @c A typical command sequence may be:
6319 @c @dots{} Create partitions etc.@dots{}
6320 @c # cryptsetup luksFormat /dev/sdX1
6321 @c # cryptsetup open --type luks /dev/sdX1 my-partition
6322 @c # mkfs.ext4 -L my-root /dev/mapper/my-partition
6325 In addition to e2fsprogs, the suite of tools to manipulate
6326 ext2/ext3/ext4 file systems, the installation image includes
6327 Cryptsetup/LUKS for disk encryption.
6329 Once that is done, mount the target root partition under @file{/mnt}
6330 with a command like (again, assuming @file{/dev/sda1} is the root
6334 mount /dev/sda1 /mnt
6337 Finally, if you plan to use one or more swap partitions (@pxref{Memory
6338 Concepts, swap space,, libc, The GNU C Library Reference Manual}), make
6339 sure to initialize them with @command{mkswap}. Assuming you have one
6340 swap partition on @file{/dev/sda2}, you would run:
6346 @node Proceeding with the Installation
6347 @subsection Proceeding with the Installation
6349 With the target partitions ready and the target root mounted on
6350 @file{/mnt}, we're ready to go. First, run:
6353 herd start cow-store /mnt
6356 This makes @file{/gnu/store} copy-on-write, such that packages added to it
6357 during the installation phase are written to the target disk on @file{/mnt}
6358 rather than kept in memory. This is necessary because the first phase of
6359 the @command{guix system init} command (see below) entails downloads or
6360 builds to @file{/gnu/store} which, initially, is an in-memory file system.
6362 Next, you have to edit a file and
6363 provide the declaration of the operating system to be installed. To
6364 that end, the installation system comes with two text editors: GNU nano
6365 (@pxref{Top,,, nano, GNU nano Manual}), and GNU Zile, an Emacs clone.
6366 We strongly recommend storing that file on the target root file system, say,
6367 as @file{/mnt/etc/config.scm}. Failing to do that, you will have lost your
6368 configuration file once you have rebooted into the newly-installed system.
6370 @xref{Using the Configuration System}, for an overview of the
6371 configuration file. The example configurations discussed in that
6372 section are available under @file{/etc/configuration} in the
6373 installation image. Thus, to get started with a system configuration
6374 providing a graphical display server (a ``desktop'' system), you can run
6375 something along these lines:
6379 # cp /etc/configuration/desktop.scm /mnt/etc/config.scm
6380 # zile /mnt/etc/config.scm
6383 You should pay attention to what your configuration file contains, and
6388 Make sure the @code{grub-configuration} form refers to the device you
6389 want to install GRUB on.
6392 Be sure that your partition labels match the value of their respective
6393 @code{device} fields in your @code{file-system} configuration, assuming
6394 your @code{file-system} configuration sets the value of @code{title} to
6398 Once you are done preparing the configuration file, the new system must
6399 be initialized (remember that the target root file system is mounted
6403 guix system init /mnt/etc/config.scm /mnt
6407 This copies all the necessary files and installs GRUB on
6408 @file{/dev/sdX}, unless you pass the @option{--no-grub} option. For
6409 more information, @pxref{Invoking guix system}. This command may trigger
6410 downloads or builds of missing packages, which can take some time.
6412 Once that command has completed---and hopefully succeeded!---you can run
6413 @command{reboot} and boot into the new system. The @code{root} password
6414 in the new system is initially empty; other users' passwords need to be
6415 initialized by running the @command{passwd} command as @code{root},
6416 unless your configuration specifies otherwise
6417 (@pxref{user-account-password, user account passwords}).
6419 Join us on @code{#guix} on the Freenode IRC network or on
6420 @file{guix-devel@@gnu.org} to share your experience---good or not so
6423 @node Building the Installation Image
6424 @subsection Building the Installation Image
6426 The installation image described above was built using the @command{guix
6427 system} command, specifically:
6429 @c FIXME: 1G is too much; see <http://bugs.gnu.org/23077>.
6431 guix system disk-image --image-size=1G gnu/system/install.scm
6434 Have a look at @file{gnu/system/install.scm} in the source tree,
6435 and see also @ref{Invoking guix system} for more information
6436 about the installation image.
6438 @node System Configuration
6439 @section System Configuration
6441 @cindex system configuration
6442 The Guix System Distribution supports a consistent whole-system configuration
6443 mechanism. By that we mean that all aspects of the global system
6444 configuration---such as the available system services, timezone and
6445 locale settings, user accounts---are declared in a single place. Such
6446 a @dfn{system configuration} can be @dfn{instantiated}---i.e., effected.
6448 One of the advantages of putting all the system configuration under the
6449 control of Guix is that it supports transactional system upgrades, and
6450 makes it possible to roll back to a previous system instantiation,
6451 should something go wrong with the new one (@pxref{Features}). Another
6452 advantage is that it makes it easy to replicate the exact same configuration
6453 across different machines, or at different points in time, without
6454 having to resort to additional administration tools layered on top of
6455 the own tools of the system.
6456 @c Yes, we're talking of Puppet, Chef, & co. here. ↑
6458 This section describes this mechanism. First we focus on the system
6459 administrator's viewpoint---explaining how the system is configured and
6460 instantiated. Then we show how this mechanism can be extended, for
6461 instance to support new system services.
6464 * Using the Configuration System:: Customizing your GNU system.
6465 * operating-system Reference:: Detail of operating-system declarations.
6466 * File Systems:: Configuring file system mounts.
6467 * Mapped Devices:: Block device extra processing.
6468 * User Accounts:: Specifying user accounts.
6469 * Locales:: Language and cultural convention settings.
6470 * Services:: Specifying system services.
6471 * Setuid Programs:: Programs running with root privileges.
6472 * X.509 Certificates:: Authenticating HTTPS servers.
6473 * Name Service Switch:: Configuring libc's name service switch.
6474 * Initial RAM Disk:: Linux-Libre bootstrapping.
6475 * GRUB Configuration:: Configuring the boot loader.
6476 * Invoking guix system:: Instantiating a system configuration.
6477 * Running GuixSD in a VM:: How to run GuixSD in a virtual machine.
6478 * Defining Services:: Adding new service definitions.
6481 @node Using the Configuration System
6482 @subsection Using the Configuration System
6484 The operating system is configured by providing an
6485 @code{operating-system} declaration in a file that can then be passed to
6486 the @command{guix system} command (@pxref{Invoking guix system}). A
6487 simple setup, with the default system services, the default Linux-Libre
6488 kernel, initial RAM disk, and boot loader looks like this:
6490 @findex operating-system
6492 @include os-config-bare-bones.texi
6495 This example should be self-describing. Some of the fields defined
6496 above, such as @code{host-name} and @code{bootloader}, are mandatory.
6497 Others, such as @code{packages} and @code{services}, can be omitted, in
6498 which case they get a default value.
6500 Below we discuss the effect of some of the most important fields
6501 (@pxref{operating-system Reference}, for details about all the available
6502 fields), and how to @dfn{instantiate} the operating system using
6503 @command{guix system}.
6505 @unnumberedsubsubsec Globally-Visible Packages
6507 @vindex %base-packages
6508 The @code{packages} field lists packages that will be globally visible
6509 on the system, for all user accounts---i.e., in every user's @code{PATH}
6510 environment variable---in addition to the per-user profiles
6511 (@pxref{Invoking guix package}). The @var{%base-packages} variable
6512 provides all the tools one would expect for basic user and administrator
6513 tasks---including the GNU Core Utilities, the GNU Networking Utilities,
6514 the GNU Zile lightweight text editor, @command{find}, @command{grep},
6515 etc. The example above adds tcpdump to those, taken from the @code{(gnu
6516 packages admin)} module (@pxref{Package Modules}).
6518 @findex specification->package
6519 Referring to packages by variable name, like @var{tcpdump} above, has
6520 the advantage of being unambiguous; it also allows typos and such to be
6521 diagnosed right away as ``unbound variables''. The downside is that one
6522 needs to know which module defines which package, and to augment the
6523 @code{use-package-modules} line accordingly. To avoid that, one can use
6524 the @code{specification->package} procedure of the @code{(gnu packages)}
6525 module, which returns the best package for a given name or name and
6529 (use-modules (gnu packages))
6533 (packages (append (map specification->package
6534 '("tcpdump" "htop" "gnupg@@2.0"))
6538 @unnumberedsubsubsec System Services
6540 @vindex %base-services
6541 The @code{services} field lists @dfn{system services} to be made
6542 available when the system starts (@pxref{Services}).
6543 The @code{operating-system} declaration above specifies that, in
6544 addition to the basic services, we want the @command{lshd} secure shell
6545 daemon listening on port 2222 (@pxref{Networking Services,
6546 @code{lsh-service}}). Under the hood,
6547 @code{lsh-service} arranges so that @code{lshd} is started with the
6548 right command-line options, possibly with supporting configuration files
6549 generated as needed (@pxref{Defining Services}).
6551 @cindex customization, of services
6552 @findex modify-services
6553 Occasionally, instead of using the base services as is, you will want to
6554 customize them. To do this, use @code{modify-services} (@pxref{Service
6555 Reference, @code{modify-services}}) to modify the list.
6557 For example, suppose you want to modify @code{guix-daemon} and Mingetty
6558 (the console log-in) in the @var{%base-services} list (@pxref{Base
6559 Services, @code{%base-services}}). To do that, you can write the
6560 following in your operating system declaration:
6563 (define %my-services
6564 ;; My very own list of services.
6565 (modify-services %base-services
6566 (guix-service-type config =>
6569 (use-substitutes? #f)
6570 (extra-options '("--gc-keep-derivations"))))
6571 (mingetty-service-type config =>
6572 (mingetty-configuration
6574 (motd (plain-file "motd" "Howdy!"))))))
6578 (services %my-services))
6581 This changes the configuration---i.e., the service parameters---of the
6582 @code{guix-service-type} instance, and that of all the
6583 @code{mingetty-service-type} instances in the @var{%base-services} list.
6584 Observe how this is accomplished: first, we arrange for the original
6585 configuration to be bound to the identifier @code{config} in the
6586 @var{body}, and then we write the @var{body} so that it evaluates to the
6587 desired configuration. In particular, notice how we use @code{inherit}
6588 to create a new configuration which has the same values as the old
6589 configuration, but with a few modifications.
6591 The configuration for a typical ``desktop'' usage, with the X11 display
6592 server, GNOME and Xfce (users can choose which of these desktop
6593 environments to use at the log-in screen by pressing @kbd{F1}), network
6594 management, power management, and more, would look like this:
6597 @include os-config-desktop.texi
6600 A graphical environment with a choice of lightweight window managers
6601 instead of full-blown desktop environments would look like this:
6604 @include os-config-lightweight-desktop.texi
6607 @xref{Desktop Services}, for the exact list of services provided by
6608 @var{%desktop-services}. @xref{X.509 Certificates}, for background
6609 information about the @code{nss-certs} package that is used here.
6611 Again, @var{%desktop-services} is just a list of service objects. If
6612 you want to remove services from there, you can do so using the
6613 procedures for list filtering (@pxref{SRFI-1 Filtering and
6614 Partitioning,,, guile, GNU Guile Reference Manual}). For instance, the
6615 following expression returns a list that contains all the services in
6616 @var{%desktop-services} minus the Avahi service:
6619 (remove (lambda (service)
6620 (eq? (service-kind service) avahi-service-type))
6624 @unnumberedsubsubsec Instantiating the System
6626 Assuming the @code{operating-system} declaration
6627 is stored in the @file{my-system-config.scm}
6628 file, the @command{guix system reconfigure my-system-config.scm} command
6629 instantiates that configuration, and makes it the default GRUB boot
6630 entry (@pxref{Invoking guix system}).
6632 The normal way to change the system configuration is by updating this
6633 file and re-running @command{guix system reconfigure}. One should never
6634 have to touch files in @command{/etc} or to run commands that modify the
6635 system state such as @command{useradd} or @command{grub-install}. In
6636 fact, you must avoid that since that would not only void your warranty
6637 but also prevent you from rolling back to previous versions of your
6638 system, should you ever need to.
6640 @cindex roll-back, of the operating system
6641 Speaking of roll-back, each time you run @command{guix system
6642 reconfigure}, a new @dfn{generation} of the system is created---without
6643 modifying or deleting previous generations. Old system generations get
6644 an entry in the GRUB boot menu, allowing you to boot them in case
6645 something went wrong with the latest generation. Reassuring, no? The
6646 @command{guix system list-generations} command lists the system
6647 generations available on disk.
6649 @unnumberedsubsubsec The Programming Interface
6651 At the Scheme level, the bulk of an @code{operating-system} declaration
6652 is instantiated with the following monadic procedure (@pxref{The Store
6655 @deffn {Monadic Procedure} operating-system-derivation os
6656 Return a derivation that builds @var{os}, an @code{operating-system}
6657 object (@pxref{Derivations}).
6659 The output of the derivation is a single directory that refers to all
6660 the packages, configuration files, and other supporting files needed to
6661 instantiate @var{os}.
6664 This procedure is provided by the @code{(gnu system)} module. Along
6665 with @code{(gnu services)} (@pxref{Services}), this module contains the
6666 guts of GuixSD. Make sure to visit it!
6669 @node operating-system Reference
6670 @subsection @code{operating-system} Reference
6672 This section summarizes all the options available in
6673 @code{operating-system} declarations (@pxref{Using the Configuration
6676 @deftp {Data Type} operating-system
6677 This is the data type representing an operating system configuration.
6678 By that, we mean all the global system configuration, not per-user
6679 configuration (@pxref{Using the Configuration System}).
6682 @item @code{kernel} (default: @var{linux-libre})
6683 The package object of the operating system kernel to use@footnote{Currently
6684 only the Linux-libre kernel is supported. In the future, it will be
6685 possible to use the GNU@tie{}Hurd.}.
6687 @item @code{kernel-arguments} (default: @code{'()})
6688 List of strings or gexps representing additional arguments to pass on
6689 the command-line of the kernel---e.g., @code{("console=ttyS0")}.
6691 @item @code{bootloader}
6692 The system bootloader configuration object. @xref{GRUB Configuration}.
6694 @item @code{initrd} (default: @code{base-initrd})
6695 A two-argument monadic procedure that returns an initial RAM disk for
6696 the Linux kernel. @xref{Initial RAM Disk}.
6698 @item @code{firmware} (default: @var{%base-firmware})
6700 List of firmware packages loadable by the operating system kernel.
6702 The default includes firmware needed for Atheros-based WiFi devices
6703 (Linux-libre module @code{ath9k}). @xref{Hardware Considerations}, for
6704 more info on supported hardware.
6706 @item @code{host-name}
6709 @item @code{hosts-file}
6711 A file-like object (@pxref{G-Expressions, file-like objects}) for use as
6712 @file{/etc/hosts} (@pxref{Host Names,,, libc, The GNU C Library
6713 Reference Manual}). The default is a file with entries for
6714 @code{localhost} and @var{host-name}.
6716 @item @code{mapped-devices} (default: @code{'()})
6717 A list of mapped devices. @xref{Mapped Devices}.
6719 @item @code{file-systems}
6720 A list of file systems. @xref{File Systems}.
6722 @item @code{swap-devices} (default: @code{'()})
6723 @cindex swap devices
6724 A list of strings identifying devices to be used for ``swap space''
6725 (@pxref{Memory Concepts,,, libc, The GNU C Library Reference Manual}).
6726 For example, @code{'("/dev/sda3")}.
6728 @item @code{users} (default: @code{%base-user-accounts})
6729 @itemx @code{groups} (default: @var{%base-groups})
6730 List of user accounts and groups. @xref{User Accounts}.
6732 @item @code{skeletons} (default: @code{(default-skeletons)})
6733 A list target file name/file-like object tuples (@pxref{G-Expressions,
6734 file-like objects}). These are the skeleton files that will be added to
6735 the home directory of newly-created user accounts.
6737 For instance, a valid value may look like this:
6740 `((".bashrc" ,(plain-file "bashrc" "echo Hello\n"))
6741 (".guile" ,(plain-file "guile"
6742 "(use-modules (ice-9 readline))
6743 (activate-readline)")))
6746 @item @code{issue} (default: @var{%default-issue})
6747 A string denoting the contents of the @file{/etc/issue} file, which is
6748 displayed when users log in on a text console.
6750 @item @code{packages} (default: @var{%base-packages})
6751 The set of packages installed in the global profile, which is accessible
6752 at @file{/run/current-system/profile}.
6754 The default set includes core utilities and it is good practice to
6755 install non-core utilities in user profiles (@pxref{Invoking guix
6758 @item @code{timezone}
6759 A timezone identifying string---e.g., @code{"Europe/Paris"}.
6761 You can run the @command{tzselect} command to find out which timezone
6762 string corresponds to your region. Choosing an invalid timezone name
6763 causes @command{guix system} to fail.
6765 @item @code{locale} (default: @code{"en_US.utf8"})
6766 The name of the default locale (@pxref{Locale Names,,, libc, The GNU C
6767 Library Reference Manual}). @xref{Locales}, for more information.
6769 @item @code{locale-definitions} (default: @var{%default-locale-definitions})
6770 The list of locale definitions to be compiled and that may be used at
6771 run time. @xref{Locales}.
6773 @item @code{locale-libcs} (default: @code{(list @var{glibc})})
6774 The list of GNU@tie{}libc packages whose locale data and tools are used
6775 to build the locale definitions. @xref{Locales}, for compatibility
6776 considerations that justify this option.
6778 @item @code{name-service-switch} (default: @var{%default-nss})
6779 Configuration of the libc name service switch (NSS)---a
6780 @code{<name-service-switch>} object. @xref{Name Service Switch}, for
6783 @item @code{services} (default: @var{%base-services})
6784 A list of service objects denoting system services. @xref{Services}.
6786 @item @code{pam-services} (default: @code{(base-pam-services)})
6788 @cindex pluggable authentication modules
6789 Linux @dfn{pluggable authentication module} (PAM) services.
6790 @c FIXME: Add xref to PAM services section.
6792 @item @code{setuid-programs} (default: @var{%setuid-programs})
6793 List of string-valued G-expressions denoting setuid programs.
6794 @xref{Setuid Programs}.
6796 @item @code{sudoers-file} (default: @var{%sudoers-specification})
6797 @cindex sudoers file
6798 The contents of the @file{/etc/sudoers} file as a file-like object
6799 (@pxref{G-Expressions, @code{local-file} and @code{plain-file}}).
6801 This file specifies which users can use the @command{sudo} command, what
6802 they are allowed to do, and what privileges they may gain. The default
6803 is that only @code{root} and members of the @code{wheel} group may use
6810 @subsection File Systems
6812 The list of file systems to be mounted is specified in the
6813 @code{file-systems} field of the operating system declaration
6814 (@pxref{Using the Configuration System}). Each file system is declared
6815 using the @code{file-system} form, like this:
6819 (mount-point "/home")
6820 (device "/dev/sda3")
6824 As usual, some of the fields are mandatory---those shown in the example
6825 above---while others can be omitted. These are described below.
6827 @deftp {Data Type} file-system
6828 Objects of this type represent file systems to be mounted. They
6829 contain the following members:
6833 This is a string specifying the type of the file system---e.g.,
6836 @item @code{mount-point}
6837 This designates the place where the file system is to be mounted.
6840 This names the ``source'' of the file system. By default it is the name
6841 of a node under @file{/dev}, but its meaning depends on the @code{title}
6842 field described below.
6844 @item @code{title} (default: @code{'device})
6845 This is a symbol that specifies how the @code{device} field is to be
6848 When it is the symbol @code{device}, then the @code{device} field is
6849 interpreted as a file name; when it is @code{label}, then @code{device}
6850 is interpreted as a partition label name; when it is @code{uuid},
6851 @code{device} is interpreted as a partition unique identifier (UUID).
6853 UUIDs may be converted from their string representation (as shown by the
6854 @command{tune2fs -l} command) using the @code{uuid} form@footnote{The
6855 @code{uuid} form expects 16-byte UUIDs as defined in
6856 @uref{https://tools.ietf.org/html/rfc4122, RFC@tie{}4122}. This is the
6857 form of UUID used by the ext2 family of file systems and others, but it
6858 is different from ``UUIDs'' found in FAT file systems, for instance.},
6863 (mount-point "/home")
6866 (device (uuid "4dab5feb-d176-45de-b287-9b0a6e4c01cb")))
6869 The @code{label} and @code{uuid} options offer a way to refer to disk
6870 partitions without having to hard-code their actual device
6871 name@footnote{Note that, while it is tempting to use
6872 @file{/dev/disk/by-uuid} and similar device names to achieve the same
6873 result, this is not recommended: These special device nodes are created
6874 by the udev daemon and may be unavailable at the time the device is
6877 However, when the source of a file system is a mapped device (@pxref{Mapped
6878 Devices}), its @code{device} field @emph{must} refer to the mapped
6879 device name---e.g., @file{/dev/mapper/root-partition}---and consequently
6880 @code{title} must be set to @code{'device}. This is required so that
6881 the system knows that mounting the file system depends on having the
6882 corresponding device mapping established.
6884 @item @code{flags} (default: @code{'()})
6885 This is a list of symbols denoting mount flags. Recognized flags
6886 include @code{read-only}, @code{bind-mount}, @code{no-dev} (disallow
6887 access to special files), @code{no-suid} (ignore setuid and setgid
6888 bits), and @code{no-exec} (disallow program execution.)
6890 @item @code{options} (default: @code{#f})
6891 This is either @code{#f}, or a string denoting mount options.
6893 @item @code{mount?} (default: @code{#t})
6894 This value indicates whether to automatically mount the file system when
6895 the system is brought up. When set to @code{#f}, the file system gets
6896 an entry in @file{/etc/fstab} (read by the @command{mount} command) but
6897 is not automatically mounted.
6899 @item @code{needed-for-boot?} (default: @code{#f})
6900 This Boolean value indicates whether the file system is needed when
6901 booting. If that is true, then the file system is mounted when the
6902 initial RAM disk (initrd) is loaded. This is always the case, for
6903 instance, for the root file system.
6905 @item @code{check?} (default: @code{#t})
6906 This Boolean indicates whether the file system needs to be checked for
6907 errors before being mounted.
6909 @item @code{create-mount-point?} (default: @code{#f})
6910 When true, the mount point is created if it does not exist yet.
6912 @item @code{dependencies} (default: @code{'()})
6913 This is a list of @code{<file-system>} objects representing file systems
6914 that must be mounted before (and unmounted after) this one.
6916 As an example, consider a hierarchy of mounts: @file{/sys/fs/cgroup} is
6917 a dependency of @file{/sys/fs/cgroup/cpu} and
6918 @file{/sys/fs/cgroup/memory}.
6923 The @code{(gnu system file-systems)} exports the following useful
6926 @defvr {Scheme Variable} %base-file-systems
6927 These are essential file systems that are required on normal systems,
6928 such as @var{%pseudo-terminal-file-system} and @var{%immutable-store} (see
6929 below.) Operating system declarations should always contain at least
6933 @defvr {Scheme Variable} %pseudo-terminal-file-system
6934 This is the file system to be mounted as @file{/dev/pts}. It supports
6935 @dfn{pseudo-terminals} created @i{via} @code{openpty} and similar
6936 functions (@pxref{Pseudo-Terminals,,, libc, The GNU C Library Reference
6937 Manual}). Pseudo-terminals are used by terminal emulators such as
6941 @defvr {Scheme Variable} %shared-memory-file-system
6942 This file system is mounted as @file{/dev/shm} and is used to support
6943 memory sharing across processes (@pxref{Memory-mapped I/O,
6944 @code{shm_open},, libc, The GNU C Library Reference Manual}).
6947 @defvr {Scheme Variable} %immutable-store
6948 This file system performs a read-only ``bind mount'' of
6949 @file{/gnu/store}, making it read-only for all the users including
6950 @code{root}. This prevents against accidental modification by software
6951 running as @code{root} or by system administrators.
6953 The daemon itself is still able to write to the store: it remounts it
6954 read-write in its own ``name space.''
6957 @defvr {Scheme Variable} %binary-format-file-system
6958 The @code{binfmt_misc} file system, which allows handling of arbitrary
6959 executable file types to be delegated to user space. This requires the
6960 @code{binfmt.ko} kernel module to be loaded.
6963 @defvr {Scheme Variable} %fuse-control-file-system
6964 The @code{fusectl} file system, which allows unprivileged users to mount
6965 and unmount user-space FUSE file systems. This requires the
6966 @code{fuse.ko} kernel module to be loaded.
6969 @node Mapped Devices
6970 @subsection Mapped Devices
6972 @cindex device mapping
6973 @cindex mapped devices
6974 The Linux kernel has a notion of @dfn{device mapping}: a block device,
6975 such as a hard disk partition, can be @dfn{mapped} into another device,
6976 usually in @code{/dev/mapper/},
6977 with additional processing over the data that flows through
6978 it@footnote{Note that the GNU@tie{}Hurd makes no difference between the
6979 concept of a ``mapped device'' and that of a file system: both boil down
6980 to @emph{translating} input/output operations made on a file to
6981 operations on its backing store. Thus, the Hurd implements mapped
6982 devices, like file systems, using the generic @dfn{translator} mechanism
6983 (@pxref{Translators,,, hurd, The GNU Hurd Reference Manual}).}. A
6984 typical example is encryption device mapping: all writes to the mapped
6985 device are encrypted, and all reads are deciphered, transparently.
6986 Guix extends this notion by considering any device or set of devices that
6987 are @dfn{transformed} in some way to create a new device; for instance,
6988 RAID devices are obtained by @dfn{assembling} several other devices, such
6989 as hard disks or partitions, into a new one that behaves as one partition.
6990 Other examples, not yet implemented, are LVM logical volumes.
6992 Mapped devices are declared using the @code{mapped-device} form,
6993 defined as follows; for examples, see below.
6995 @deftp {Data Type} mapped-device
6996 Objects of this type represent device mappings that will be made when
6997 the system boots up.
7001 This is either a string specifying the name of the block device to be mapped,
7002 such as @code{"/dev/sda3"}, or a list of such strings when several devices
7003 need to be assembled for creating a new one.
7006 This string specifies the name of the resulting mapped device. For
7007 kernel mappers such as encrypted devices of type @code{luks-device-mapping},
7008 specifying @code{"my-partition"} leads to the creation of
7009 the @code{"/dev/mapper/my-partition"} device.
7010 For RAID devices of type @code{raid-device-mapping}, the full device name
7011 such as @code{"/dev/md0"} needs to be given.
7014 This must be a @code{mapped-device-kind} object, which specifies how
7015 @var{source} is mapped to @var{target}.
7019 @defvr {Scheme Variable} luks-device-mapping
7020 This defines LUKS block device encryption using the @command{cryptsetup}
7021 command from the package with the same name. It relies on the
7022 @code{dm-crypt} Linux kernel module.
7025 @defvr {Scheme Variable} raid-device-mapping
7026 This defines a RAID device, which is assembled using the @code{mdadm}
7027 command from the package with the same name. It requires a Linux kernel
7028 module for the appropriate RAID level to be loaded, such as @code{raid456}
7029 for RAID-4, RAID-5 or RAID-6, or @code{raid10} for RAID-10.
7032 @cindex disk encryption
7034 The following example specifies a mapping from @file{/dev/sda3} to
7035 @file{/dev/mapper/home} using LUKS---the
7036 @url{http://code.google.com/p/cryptsetup,Linux Unified Key Setup}, a
7037 standard mechanism for disk encryption.
7038 The @file{/dev/mapper/home}
7039 device can then be used as the @code{device} of a @code{file-system}
7040 declaration (@pxref{File Systems}).
7044 (source "/dev/sda3")
7046 (type luks-device-mapping))
7049 Alternatively, to become independent of device numbering, one may obtain
7050 the LUKS UUID (@dfn{unique identifier}) of the source device by a
7054 cryptsetup luksUUID /dev/sda3
7057 and use it as follows:
7061 (source (uuid "cb67fc72-0d54-4c88-9d4b-b225f30b0f44"))
7063 (type luks-device-mapping))
7066 A RAID device formed of the partitions @file{/dev/sda1} and @file{/dev/sdb1}
7067 may be declared as follows:
7071 (source (list "/dev/sda1" "/dev/sdb1"))
7073 (type raid-device-mapping))
7076 The @file{/dev/md0} device can then be used as the @code{device} of a
7077 @code{file-system} declaration (@pxref{File Systems}).
7078 Note that the RAID level need not be given; it is chosen during the
7079 initial creation and formatting of the RAID device and is determined
7080 automatically later.
7084 @subsection User Accounts
7086 User accounts and groups are entirely managed through the
7087 @code{operating-system} declaration. They are specified with the
7088 @code{user-account} and @code{user-group} forms:
7094 (supplementary-groups '("wheel" ;allow use of sudo, etc.
7096 "video" ;video devices such as webcams
7097 "cdrom")) ;the good ol' CD-ROM
7098 (comment "Bob's sister")
7099 (home-directory "/home/alice"))
7102 When booting or upon completion of @command{guix system reconfigure},
7103 the system ensures that only the user accounts and groups specified in
7104 the @code{operating-system} declaration exist, and with the specified
7105 properties. Thus, account or group creations or modifications made by
7106 directly invoking commands such as @command{useradd} are lost upon
7107 reconfiguration or reboot. This ensures that the system remains exactly
7110 @deftp {Data Type} user-account
7111 Objects of this type represent user accounts. The following members may
7116 The name of the user account.
7119 This is the name (a string) or identifier (a number) of the user group
7120 this account belongs to.
7122 @item @code{supplementary-groups} (default: @code{'()})
7123 Optionally, this can be defined as a list of group names that this
7126 @item @code{uid} (default: @code{#f})
7127 This is the user ID for this account (a number), or @code{#f}. In the
7128 latter case, a number is automatically chosen by the system when the
7131 @item @code{comment} (default: @code{""})
7132 A comment about the account, such as the account owner's full name.
7134 @item @code{home-directory}
7135 This is the name of the home directory for the account.
7137 @item @code{shell} (default: Bash)
7138 This is a G-expression denoting the file name of a program to be used as
7139 the shell (@pxref{G-Expressions}).
7141 @item @code{system?} (default: @code{#f})
7142 This Boolean value indicates whether the account is a ``system''
7143 account. System accounts are sometimes treated specially; for instance,
7144 graphical login managers do not list them.
7146 @anchor{user-account-password}
7147 @item @code{password} (default: @code{#f})
7148 You would normally leave this field to @code{#f}, initialize user
7149 passwords as @code{root} with the @command{passwd} command, and then let
7150 users change it with @command{passwd}. Passwords set with
7151 @command{passwd} are of course preserved across reboot and
7154 If you @emph{do} want to have a preset password for an account, then
7155 this field must contain the encrypted password, as a string.
7156 @xref{crypt,,, libc, The GNU C Library Reference Manual}, for more information
7157 on password encryption, and @ref{Encryption,,, guile, GNU Guile Reference
7158 Manual}, for information on Guile's @code{crypt} procedure.
7163 User group declarations are even simpler:
7166 (user-group (name "students"))
7169 @deftp {Data Type} user-group
7170 This type is for, well, user groups. There are just a few fields:
7174 The name of the group.
7176 @item @code{id} (default: @code{#f})
7177 The group identifier (a number). If @code{#f}, a new number is
7178 automatically allocated when the group is created.
7180 @item @code{system?} (default: @code{#f})
7181 This Boolean value indicates whether the group is a ``system'' group.
7182 System groups have low numerical IDs.
7184 @item @code{password} (default: @code{#f})
7185 What, user groups can have a password? Well, apparently yes. Unless
7186 @code{#f}, this field specifies the password of the group.
7191 For convenience, a variable lists all the basic user groups one may
7194 @defvr {Scheme Variable} %base-groups
7195 This is the list of basic user groups that users and/or packages expect
7196 to be present on the system. This includes groups such as ``root'',
7197 ``wheel'', and ``users'', as well as groups used to control access to
7198 specific devices such as ``audio'', ``disk'', and ``cdrom''.
7201 @defvr {Scheme Variable} %base-user-accounts
7202 This is the list of basic system accounts that programs may expect to
7203 find on a GNU/Linux system, such as the ``nobody'' account.
7205 Note that the ``root'' account is not included here. It is a
7206 special-case and is automatically added whether or not it is specified.
7213 A @dfn{locale} defines cultural conventions for a particular language
7214 and region of the world (@pxref{Locales,,, libc, The GNU C Library
7215 Reference Manual}). Each locale has a name that typically has the form
7216 @code{@var{language}_@var{territory}.@var{codeset}}---e.g.,
7217 @code{fr_LU.utf8} designates the locale for the French language, with
7218 cultural conventions from Luxembourg, and using the UTF-8 encoding.
7220 @cindex locale definition
7221 Usually, you will want to specify the default locale for the machine
7222 using the @code{locale} field of the @code{operating-system} declaration
7223 (@pxref{operating-system Reference, @code{locale}}).
7225 The selected locale is automatically added to the @dfn{locale
7226 definitions} known to the system if needed, with its codeset inferred
7227 from its name---e.g., @code{bo_CN.utf8} will be assumed to use the
7228 @code{UTF-8} codeset. Additional locale definitions can be specified in
7229 the @code{locale-definitions} slot of @code{operating-system}---this is
7230 useful, for instance, if the codeset could not be inferred from the
7231 locale name. The default set of locale definitions includes some widely
7232 used locales, but not all the available locales, in order to save space.
7234 For instance, to add the North Frisian locale for Germany, the value of
7238 (cons (locale-definition
7239 (name "fy_DE.utf8") (source "fy_DE"))
7240 %default-locale-definitions)
7243 Likewise, to save space, one might want @code{locale-definitions} to
7244 list only the locales that are actually used, as in:
7247 (list (locale-definition
7248 (name "ja_JP.eucjp") (source "ja_JP")
7249 (charset "EUC-JP")))
7253 The compiled locale definitions are available at
7254 @file{/run/current-system/locale/X.Y}, where @code{X.Y} is the libc
7255 version, which is the default location where the GNU@tie{}libc provided
7256 by Guix looks for locale data. This can be overridden using the
7257 @code{LOCPATH} environment variable (@pxref{locales-and-locpath,
7258 @code{LOCPATH} and locale packages}).
7260 The @code{locale-definition} form is provided by the @code{(gnu system
7261 locale)} module. Details are given below.
7263 @deftp {Data Type} locale-definition
7264 This is the data type of a locale definition.
7269 The name of the locale. @xref{Locale Names,,, libc, The GNU C Library
7270 Reference Manual}, for more information on locale names.
7273 The name of the source for that locale. This is typically the
7274 @code{@var{language}_@var{territory}} part of the locale name.
7276 @item @code{charset} (default: @code{"UTF-8"})
7277 The ``character set'' or ``code set'' for that locale,
7278 @uref{http://www.iana.org/assignments/character-sets, as defined by
7284 @defvr {Scheme Variable} %default-locale-definitions
7285 A list of commonly used UTF-8 locales, used as the default
7286 value of the @code{locale-definitions} field of @code{operating-system}
7290 @cindex normalized codeset in locale names
7291 These locale definitions use the @dfn{normalized codeset} for the part
7292 that follows the dot in the name (@pxref{Using gettextized software,
7293 normalized codeset,, libc, The GNU C Library Reference Manual}). So for
7294 instance it has @code{uk_UA.utf8} but @emph{not}, say,
7298 @subsubsection Locale Data Compatibility Considerations
7300 @cindex incompatibility, of locale data
7301 @code{operating-system} declarations provide a @code{locale-libcs} field
7302 to specify the GNU@tie{}libc packages that are used to compile locale
7303 declarations (@pxref{operating-system Reference}). ``Why would I
7304 care?'', you may ask. Well, it turns out that the binary format of
7305 locale data is occasionally incompatible from one libc version to
7308 @c See <https://sourceware.org/ml/libc-alpha/2015-09/msg00575.html>
7309 @c and <https://lists.gnu.org/archive/html/guix-devel/2015-08/msg00737.html>.
7310 For instance, a program linked against libc version 2.21 is unable to
7311 read locale data produced with libc 2.22; worse, that program
7312 @emph{aborts} instead of simply ignoring the incompatible locale
7313 data@footnote{Versions 2.23 and later of GNU@tie{}libc will simply skip
7314 the incompatible locale data, which is already an improvement.}.
7315 Similarly, a program linked against libc 2.22 can read most, but not
7316 all, the locale data from libc 2.21 (specifically, @code{LC_COLLATE}
7317 data is incompatible); thus calls to @code{setlocale} may fail, but
7318 programs will not abort.
7320 The ``problem'' in GuixSD is that users have a lot of freedom: They can
7321 choose whether and when to upgrade software in their profiles, and might
7322 be using a libc version different from the one the system administrator
7323 used to build the system-wide locale data.
7325 Fortunately, unprivileged users can also install their own locale data
7326 and define @var{GUIX_LOCPATH} accordingly (@pxref{locales-and-locpath,
7327 @code{GUIX_LOCPATH} and locale packages}).
7329 Still, it is best if the system-wide locale data at
7330 @file{/run/current-system/locale} is built for all the libc versions
7331 actually in use on the system, so that all the programs can access
7332 it---this is especially crucial on a multi-user system. To do that, the
7333 administrator can specify several libc packages in the
7334 @code{locale-libcs} field of @code{operating-system}:
7337 (use-package-modules base)
7341 (locale-libcs (list glibc-2.21 (canonical-package glibc))))
7344 This example would lead to a system containing locale definitions for
7345 both libc 2.21 and the current version of libc in
7346 @file{/run/current-system/locale}.
7350 @subsection Services
7352 @cindex system services
7353 An important part of preparing an @code{operating-system} declaration is
7354 listing @dfn{system services} and their configuration (@pxref{Using the
7355 Configuration System}). System services are typically daemons launched
7356 when the system boots, or other actions needed at that time---e.g.,
7357 configuring network access.
7359 Services are managed by the GNU@tie{}Shepherd (@pxref{Introduction,,,
7360 shepherd, The GNU Shepherd Manual}). On a running system, the
7361 @command{herd} command allows you to list the available services, show
7362 their status, start and stop them, or do other specific operations
7363 (@pxref{Jump Start,,, shepherd, The GNU Shepherd Manual}). For example:
7369 The above command, run as @code{root}, lists the currently defined
7370 services. The @command{herd doc} command shows a synopsis of the given
7375 Run libc's name service cache daemon (nscd).
7378 The @command{start}, @command{stop}, and @command{restart} sub-commands
7379 have the effect you would expect. For instance, the commands below stop
7380 the nscd service and restart the Xorg display server:
7384 Service nscd has been stopped.
7385 # herd restart xorg-server
7386 Service xorg-server has been stopped.
7387 Service xorg-server has been started.
7390 The following sections document the available services, starting with
7391 the core services, that may be used in an @code{operating-system}
7395 * Base Services:: Essential system services.
7396 * Scheduled Job Execution:: The mcron service.
7397 * Networking Services:: Network setup, SSH daemon, etc.
7398 * X Window:: Graphical display.
7399 * Desktop Services:: D-Bus and desktop services.
7400 * Database Services:: SQL databases.
7401 * Mail Services:: IMAP, POP3, SMTP, and all that.
7402 * Web Services:: Web servers.
7403 * Various Services:: Other services.
7407 @subsubsection Base Services
7409 The @code{(gnu services base)} module provides definitions for the basic
7410 services that one expects from the system. The services exported by
7411 this module are listed below.
7413 @defvr {Scheme Variable} %base-services
7414 This variable contains a list of basic services (@pxref{Service Types
7415 and Services}, for more information on service objects) one would
7416 expect from the system: a login service (mingetty) on each tty, syslogd,
7417 the libc name service cache daemon (nscd), the udev device manager, and
7420 This is the default value of the @code{services} field of
7421 @code{operating-system} declarations. Usually, when customizing a
7422 system, you will want to append services to @var{%base-services}, like
7426 (cons* (avahi-service) (lsh-service) %base-services)
7430 @deffn {Scheme Procedure} host-name-service @var{name}
7431 Return a service that sets the host name to @var{name}.
7434 @deffn {Scheme Procedure} mingetty-service @var{config}
7435 Return a service to run mingetty according to @var{config}, a
7436 @code{<mingetty-configuration>} object, which specifies the tty to run, among
7440 @deftp {Data Type} mingetty-configuration
7441 This is the data type representing the configuration of Mingetty, which
7442 implements console log-in.
7447 The name of the console this Mingetty runs on---e.g., @code{"tty1"}.
7450 A file-like object containing the ``message of the day''.
7452 @item @code{auto-login} (default: @code{#f})
7453 When true, this field must be a string denoting the user name under
7454 which the system automatically logs in. When it is @code{#f}, a
7455 user name and password must be entered to log in.
7457 @item @code{login-program} (default: @code{#f})
7458 This must be either @code{#f}, in which case the default log-in program
7459 is used (@command{login} from the Shadow tool suite), or a gexp denoting
7460 the name of the log-in program.
7462 @item @code{login-pause?} (default: @code{#f})
7463 When set to @code{#t} in conjunction with @var{auto-login}, the user
7464 will have to press a key before the log-in shell is launched.
7466 @item @code{mingetty} (default: @var{mingetty})
7467 The Mingetty package to use.
7472 @cindex name service cache daemon
7474 @deffn {Scheme Procedure} nscd-service [@var{config}] [#:glibc glibc] @
7475 [#:name-services '()]
7476 Return a service that runs the libc name service cache daemon (nscd) with the
7477 given @var{config}---an @code{<nscd-configuration>} object. @xref{Name
7478 Service Switch}, for an example.
7481 @defvr {Scheme Variable} %nscd-default-configuration
7482 This is the default @code{<nscd-configuration>} value (see below) used
7483 by @code{nscd-service}. It uses the caches defined by
7484 @var{%nscd-default-caches}; see below.
7487 @deftp {Data Type} nscd-configuration
7488 This is the data type representing the name service cache daemon (nscd)
7493 @item @code{name-services} (default: @code{'()})
7494 List of packages denoting @dfn{name services} that must be visible to
7495 the nscd---e.g., @code{(list @var{nss-mdns})}.
7497 @item @code{glibc} (default: @var{glibc})
7498 Package object denoting the GNU C Library providing the @command{nscd}
7501 @item @code{log-file} (default: @code{"/var/log/nscd.log"})
7502 Name of the nscd log file. This is where debugging output goes when
7503 @code{debug-level} is strictly positive.
7505 @item @code{debug-level} (default: @code{0})
7506 Integer denoting the debugging levels. Higher numbers mean that more
7507 debugging output is logged.
7509 @item @code{caches} (default: @var{%nscd-default-caches})
7510 List of @code{<nscd-cache>} objects denoting things to be cached; see
7516 @deftp {Data Type} nscd-cache
7517 Data type representing a cache database of nscd and its parameters.
7521 @item @code{database}
7522 This is a symbol representing the name of the database to be cached.
7523 Valid values are @code{passwd}, @code{group}, @code{hosts}, and
7524 @code{services}, which designate the corresponding NSS database
7525 (@pxref{NSS Basics,,, libc, The GNU C Library Reference Manual}).
7527 @item @code{positive-time-to-live}
7528 @itemx @code{negative-time-to-live} (default: @code{20})
7529 A number representing the number of seconds during which a positive or
7530 negative lookup result remains in cache.
7532 @item @code{check-files?} (default: @code{#t})
7533 Whether to check for updates of the files corresponding to
7536 For instance, when @var{database} is @code{hosts}, setting this flag
7537 instructs nscd to check for updates in @file{/etc/hosts} and to take
7540 @item @code{persistent?} (default: @code{#t})
7541 Whether the cache should be stored persistently on disk.
7543 @item @code{shared?} (default: @code{#t})
7544 Whether the cache should be shared among users.
7546 @item @code{max-database-size} (default: 32@tie{}MiB)
7547 Maximum size in bytes of the database cache.
7549 @c XXX: 'suggested-size' and 'auto-propagate?' seem to be expert
7550 @c settings, so leave them out.
7555 @defvr {Scheme Variable} %nscd-default-caches
7556 List of @code{<nscd-cache>} objects used by default by
7557 @code{nscd-configuration} (see above).
7559 It enables persistent and aggressive caching of service and host name
7560 lookups. The latter provides better host name lookup performance,
7561 resilience in the face of unreliable name servers, and also better
7562 privacy---often the result of host name lookups is in local cache, so
7563 external name servers do not even need to be queried.
7567 @deffn {Scheme Procedure} syslog-service @
7568 [#:config-file @var{%default-syslog.conf}]
7569 Return a service that runs @command{syslogd}. If the configuration file
7570 name @var{config-file} is not specified, use some reasonable default
7573 @xref{syslogd invocation,,, inetutils, GNU Inetutils}, for more
7574 information on the configuration file syntax.
7577 @anchor{guix-configuration-type}
7578 @deftp {Data Type} guix-configuration
7579 This data type represents the configuration of the Guix build daemon.
7580 @xref{Invoking guix-daemon}, for more information.
7583 @item @code{guix} (default: @var{guix})
7584 The Guix package to use.
7586 @item @code{build-group} (default: @code{"guixbuild"})
7587 Name of the group for build user accounts.
7589 @item @code{build-accounts} (default: @code{10})
7590 Number of build user accounts to create.
7592 @item @code{authorize-key?} (default: @code{#t})
7593 Whether to authorize the substitute key for @code{hydra.gnu.org}
7594 (@pxref{Substitutes}).
7596 @item @code{use-substitutes?} (default: @code{#t})
7597 Whether to use substitutes.
7599 @item @code{substitute-urls} (default: @var{%default-substitute-urls})
7600 The list of URLs where to look for substitutes by default.
7602 @item @code{extra-options} (default: @code{'()})
7603 List of extra command-line options for @command{guix-daemon}.
7605 @item @code{lsof} (default: @var{lsof})
7606 @itemx @code{lsh} (default: @var{lsh})
7607 The lsof and lsh packages to use.
7612 @deffn {Scheme Procedure} guix-service @var{config}
7613 Return a service that runs the Guix build daemon according to
7617 @deffn {Scheme Procedure} udev-service [#:udev udev]
7618 Run @var{udev}, which populates the @file{/dev} directory dynamically.
7621 @deffn {Scheme Procedure} urandom-seed-service @var{#f}
7622 Save some entropy in @var{%random-seed-file} to seed @file{/dev/urandom}
7626 @defvr {Scheme Variable} %random-seed-file
7627 This is the name of the file where some random bytes are saved by
7628 @var{urandom-seed-service} to seed @file{/dev/urandom} when rebooting.
7629 It defaults to @file{/var/lib/random-seed}.
7632 @deffn {Scheme Procedure} console-keymap-service @var{files} ...
7633 @cindex keyboard layout
7634 Return a service to load console keymaps from @var{files} using
7635 @command{loadkeys} command. Most likely, you want to load some default
7636 keymap, which can be done like this:
7639 (console-keymap-service "dvorak")
7642 Or, for example, for a Swedish keyboard, you may need to combine
7643 the following keymaps:
7645 (console-keymap-service "se-lat6" "se-fi-lat6")
7648 Also you can specify a full file name (or file names) of your keymap(s).
7649 See @code{man loadkeys} for details.
7653 @deffn {Scheme Procedure} gpm-service [#:gpm @var{gpm}] @
7655 Run @var{gpm}, the general-purpose mouse daemon, with the given
7656 command-line @var{options}. GPM allows users to use the mouse in the console,
7657 notably to select, copy, and paste text. The default value of @var{options}
7658 uses the @code{ps2} protocol, which works for both USB and PS/2 mice.
7660 This service is not part of @var{%base-services}.
7663 @anchor{guix-publish-service}
7664 @deffn {Scheme Procedure} guix-publish-service [#:guix @var{guix}] @
7665 [#:port 80] [#:host "localhost"]
7666 Return a service that runs @command{guix publish} listening on @var{host}
7667 and @var{port} (@pxref{Invoking guix publish}).
7669 This assumes that @file{/etc/guix} already contains a signing key pair as
7670 created by @command{guix archive --generate-key} (@pxref{Invoking guix
7671 archive}). If that is not the case, the service will fail to start.
7674 @anchor{rngd-service}
7675 @deffn {Scheme Procedure} rngd-service [#:rng-tools @var{rng-tools}] @
7676 [#:device "/dev/hwrng"]
7677 Return a service that runs the @command{rngd} program from @var{rng-tools}
7678 to add @var{device} to the kernel's entropy pool. The service will fail if
7679 @var{device} does not exist.
7682 @anchor{pam-limits-service}
7683 @cindex session limits
7686 @deffn {Scheme Procedure} pam-limits-service [#:limits @var{limits}]
7688 Return a service that installs a configuration file for the
7689 @uref{http://linux-pam.org/Linux-PAM-html/sag-pam_limits.html,
7690 @code{pam_limits} module}. The procedure optionally takes a list of
7691 @code{pam-limits-entry} values, which can be used to specify
7692 @code{ulimit} limits and nice priority limits to user sessions.
7694 The following limits definition sets two hard and soft limits for all
7695 login sessions of users in the @code{realtime} group:
7700 (pam-limits-entry "@@realtime" 'both 'rtprio 99)
7701 (pam-limits-entry "@@realtime" 'both 'memlock 'unlimited)))
7704 The first entry increases the maximum realtime priority for
7705 non-privileged processes; the second entry lifts any restriction of the
7706 maximum address space that can be locked in memory. These settings are
7707 commonly used for real-time audio systems.
7711 @node Scheduled Job Execution
7712 @subsubsection Scheduled Job Execution
7715 @cindex scheduling jobs
7716 The @code{(gnu services mcron)} module provides an interface to
7717 GNU@tie{}mcron, a daemon to run jobs at scheduled times (@pxref{Top,,,
7718 mcron, GNU@tie{}mcron}). GNU@tie{}mcron is similar to the traditional
7719 Unix @command{cron} daemon; the main difference is that it is
7720 implemented in Guile Scheme, which provides a lot of flexibility when
7721 specifying the scheduling of jobs and their actions.
7723 The example below defines an operating system that runs the
7724 @command{updatedb} (@pxref{Invoking updatedb,,, find, Finding Files})
7725 and the @command{guix gc} commands (@pxref{Invoking guix gc}) daily, as
7726 well as the @command{mkid} command on behalf of an unprivileged user
7727 (@pxref{mkid invocation,,, idutils, ID Database Utilities}). It uses
7728 gexps to introduce job definitions that are passed to mcron
7729 (@pxref{G-Expressions}).
7732 (use-modules (guix) (gnu) (gnu services mcron))
7733 (use-package-modules base idutils)
7735 (define updatedb-job
7736 ;; Run 'updatedb' at 3AM every day. Here we write the
7737 ;; job's action as a Scheme procedure.
7738 #~(job '(next-hour '(3))
7740 (execl (string-append #$findutils "/bin/updatedb")
7742 "--prunepaths=/tmp /var/tmp /gnu/store"))))
7744 (define garbage-collector-job
7745 ;; Collect garbage 5 minutes after midnight every day.
7746 ;; The job's action is a shell command.
7747 #~(job "5 0 * * *" ;Vixie cron syntax
7750 (define idutils-jobs
7751 ;; Update the index database as user "charlie" at 12:15PM
7752 ;; and 19:15PM. This runs from the user's home directory.
7753 #~(job '(next-minute-from (next-hour '(12 19)) '(15))
7754 (string-append #$idutils "/bin/mkid src")
7759 (services (cons (mcron-service (list garbage-collector-job
7765 @xref{Guile Syntax, mcron job specifications,, mcron, GNU@tie{}mcron},
7766 for more information on mcron job specifications. Below is the
7767 reference of the mcron service.
7769 @deffn {Scheme Procedure} mcron-service @var{jobs} [#:mcron @var{mcron2}]
7770 Return an mcron service running @var{mcron} that schedules @var{jobs}, a
7771 list of gexps denoting mcron job specifications.
7773 This is a shorthand for:
7775 (service mcron-service-type
7776 (mcron-configuration (mcron mcron) (jobs jobs)))
7780 @defvr {Scheme Variable} mcron-service-type
7781 This is the type of the @code{mcron} service, whose value is an
7782 @code{mcron-configuration} object.
7784 This service type can be the target of a service extension that provides
7785 it additional job specifications (@pxref{Service Composition}). In
7786 other words, it is possible to define services that provide addition
7790 @deftp {Data Type} mcron-configuration
7791 Data type representing the configuration of mcron.
7794 @item @code{mcron} (default: @var{mcron2})
7795 The mcron package to use.
7798 This is a list of gexps (@pxref{G-Expressions}), where each gexp
7799 corresponds to an mcron job specification (@pxref{Syntax, mcron job
7800 specifications,, mcron, GNU@tie{}mcron}).
7805 @node Networking Services
7806 @subsubsection Networking Services
7808 The @code{(gnu services networking)} module provides services to configure
7809 the network interface.
7811 @cindex DHCP, networking service
7812 @deffn {Scheme Procedure} dhcp-client-service [#:dhcp @var{isc-dhcp}]
7813 Return a service that runs @var{dhcp}, a Dynamic Host Configuration
7814 Protocol (DHCP) client, on all the non-loopback network interfaces.
7817 @deffn {Scheme Procedure} static-networking-service @var{interface} @var{ip} @
7818 [#:gateway #f] [#:name-servers @code{'()}]
7819 Return a service that starts @var{interface} with address @var{ip}. If
7820 @var{gateway} is true, it must be a string specifying the default network
7825 @cindex network management
7826 @deffn {Scheme Procedure} wicd-service [#:wicd @var{wicd}]
7827 Return a service that runs @url{https://launchpad.net/wicd,Wicd}, a network
7828 management daemon that aims to simplify wired and wireless networking.
7830 This service adds the @var{wicd} package to the global profile, providing
7831 several commands to interact with the daemon and configure networking:
7832 @command{wicd-client}, a graphical user interface, and the @command{wicd-cli}
7833 and @command{wicd-curses} user interfaces.
7836 @cindex NetworkManager
7837 @deffn {Scheme Procedure} network-manager-service @
7838 [#:network-manager @var{network-manager}]
7839 Return a service that runs NetworkManager, a network connection manager
7840 attempting to keep network connectivity active when available.
7844 @deffn {Scheme Procedure} connman-service @
7845 [#:connman @var{connman}]
7846 Return a service that runs @url{https://01.org/connman,Connman}, a network
7849 This service adds the @var{connman} package to the global profile, providing
7850 several the @command{connmanctl} command to interact with the daemon and
7851 configure networking."
7854 @deffn {Scheme Procedure} ntp-service [#:ntp @var{ntp}] @
7855 [#:name-service @var{%ntp-servers}]
7856 Return a service that runs the daemon from @var{ntp}, the
7857 @uref{http://www.ntp.org, Network Time Protocol package}. The daemon will
7858 keep the system clock synchronized with that of @var{servers}.
7861 @defvr {Scheme Variable} %ntp-servers
7862 List of host names used as the default NTP servers.
7865 @deffn {Scheme Procedure} tor-service [@var{config-file}] [#:tor @var{tor}]
7866 Return a service to run the @uref{https://torproject.org, Tor} anonymous
7869 The daemon runs as the @code{tor} unprivileged user. It is passed
7870 @var{config-file}, a file-like object, with an additional @code{User tor} line
7871 and lines for hidden services added via @code{tor-hidden-service}. Run
7872 @command{man tor} for information about the configuration file.
7875 @cindex hidden service
7876 @deffn {Scheme Procedure} tor-hidden-service @var{name} @var{mapping}
7877 Define a new Tor @dfn{hidden service} called @var{name} and implementing
7878 @var{mapping}. @var{mapping} is a list of port/host tuples, such as:
7881 '((22 "127.0.0.1:22")
7882 (80 "127.0.0.1:8080"))
7885 In this example, port 22 of the hidden service is mapped to local port 22, and
7886 port 80 is mapped to local port 8080.
7888 This creates a @file{/var/lib/tor/hidden-services/@var{name}} directory, where
7889 the @file{hostname} file contains the @code{.onion} host name for the hidden
7892 See @uref{https://www.torproject.org/docs/tor-hidden-service.html.en, the Tor
7893 project's documentation} for more information.
7896 @deffn {Scheme Procedure} bitlbee-service [#:bitlbee bitlbee] @
7897 [#:interface "127.0.0.1"] [#:port 6667] @
7898 [#:extra-settings ""]
7899 Return a service that runs @url{http://bitlbee.org,BitlBee}, a daemon that
7900 acts as a gateway between IRC and chat networks.
7902 The daemon will listen to the interface corresponding to the IP address
7903 specified in @var{interface}, on @var{port}. @code{127.0.0.1} means that only
7904 local clients can connect, whereas @code{0.0.0.0} means that connections can
7905 come from any networking interface.
7907 In addition, @var{extra-settings} specifies a string to append to the
7911 Furthermore, @code{(gnu services ssh)} provides the following services.
7913 @deffn {Scheme Procedure} lsh-service [#:host-key "/etc/lsh/host-key"] @
7914 [#:daemonic? #t] [#:interfaces '()] [#:port-number 22] @
7915 [#:allow-empty-passwords? #f] [#:root-login? #f] @
7916 [#:syslog-output? #t] [#:x11-forwarding? #t] @
7917 [#:tcp/ip-forwarding? #t] [#:password-authentication? #t] @
7918 [#:public-key-authentication? #t] [#:initialize? #t]
7919 Run the @command{lshd} program from @var{lsh} to listen on port @var{port-number}.
7920 @var{host-key} must designate a file containing the host key, and readable
7923 When @var{daemonic?} is true, @command{lshd} will detach from the
7924 controlling terminal and log its output to syslogd, unless one sets
7925 @var{syslog-output?} to false. Obviously, it also makes lsh-service
7926 depend on existence of syslogd service. When @var{pid-file?} is true,
7927 @command{lshd} writes its PID to the file called @var{pid-file}.
7929 When @var{initialize?} is true, automatically create the seed and host key
7930 upon service activation if they do not exist yet. This may take long and
7931 require interaction.
7933 When @var{initialize?} is false, it is up to the user to initialize the
7934 randomness generator (@pxref{lsh-make-seed,,, lsh, LSH Manual}), and to create
7935 a key pair with the private key stored in file @var{host-key} (@pxref{lshd
7936 basics,,, lsh, LSH Manual}).
7938 When @var{interfaces} is empty, lshd listens for connections on all the
7939 network interfaces; otherwise, @var{interfaces} must be a list of host names
7942 @var{allow-empty-passwords?} specifies whether to accept log-ins with empty
7943 passwords, and @var{root-login?} specifies whether to accept log-ins as
7946 The other options should be self-descriptive.
7949 @deffn {Scheme Procedure} dropbear-service [@var{config}]
7950 Run the @uref{https://matt.ucc.asn.au/dropbear/dropbear.html,Dropbear SSH
7951 daemon} with the given @var{config}, a @code{<dropbear-configuration>}
7954 For example, to specify a Dropbear service listening on port 1234, add
7955 this call to the operating system's @code{services} field:
7958 (dropbear-service (dropbear-configuration
7959 (port-number 1234)))
7963 @deftp {Data Type} dropbear-configuration
7964 This data type represents the configuration of a Dropbear SSH daemon.
7967 @item @code{dropbear} (default: @var{dropbear})
7968 The Dropbear package to use.
7970 @item @code{port-number} (default: 22)
7971 The TCP port where the daemon waits for incoming connections.
7973 @item @code{syslog-output?} (default: @code{#t})
7974 Whether to enable syslog output.
7976 @item @code{pid-file} (default: @code{"/var/run/dropbear.pid"})
7977 File name of the daemon's PID file.
7979 @item @code{root-login?} (default: @code{#f})
7980 Whether to allow @code{root} logins.
7982 @item @code{allow-empty-passwords?} (default: @code{#f})
7983 Whether to allow empty passwords.
7985 @item @code{password-authentication?} (default: @code{#t})
7986 Whether to enable password-based authentication.
7990 @defvr {Scheme Variable} %facebook-host-aliases
7991 This variable contains a string for use in @file{/etc/hosts}
7992 (@pxref{Host Names,,, libc, The GNU C Library Reference Manual}). Each
7993 line contains a entry that maps a known server name of the Facebook
7994 on-line service---e.g., @code{www.facebook.com}---to the local
7995 host---@code{127.0.0.1} or its IPv6 equivalent, @code{::1}.
7997 This variable is typically used in the @code{hosts-file} field of an
7998 @code{operating-system} declaration (@pxref{operating-system Reference,
7999 @file{/etc/hosts}}):
8002 (use-modules (gnu) (guix))
8005 (host-name "mymachine")
8008 ;; Create a /etc/hosts file with aliases for "localhost"
8009 ;; and "mymachine", as well as for Facebook servers.
8011 (string-append (local-host-aliases host-name)
8012 %facebook-host-aliases))))
8015 This mechanism can prevent programs running locally, such as Web
8016 browsers, from accessing Facebook.
8019 The @code{(gnu services avahi)} provides the following definition.
8021 @deffn {Scheme Procedure} avahi-service [#:avahi @var{avahi}] @
8022 [#:host-name #f] [#:publish? #t] [#:ipv4? #t] @
8023 [#:ipv6? #t] [#:wide-area? #f] @
8024 [#:domains-to-browse '()] [#:debug? #f]
8025 Return a service that runs @command{avahi-daemon}, a system-wide
8026 mDNS/DNS-SD responder that allows for service discovery and
8027 "zero-configuration" host name lookups (see @uref{http://avahi.org/}), and
8028 extends the name service cache daemon (nscd) so that it can resolve
8029 @code{.local} host names using
8030 @uref{http://0pointer.de/lennart/projects/nss-mdns/, nss-mdns}. Additionally,
8031 add the @var{avahi} package to the system profile so that commands such as
8032 @command{avahi-browse} are directly usable.
8034 If @var{host-name} is different from @code{#f}, use that as the host name to
8035 publish for this machine; otherwise, use the machine's actual host name.
8037 When @var{publish?} is true, publishing of host names and services is allowed;
8038 in particular, avahi-daemon will publish the machine's host name and IP
8039 address via mDNS on the local network.
8041 When @var{wide-area?} is true, DNS-SD over unicast DNS is enabled.
8043 Boolean values @var{ipv4?} and @var{ipv6?} determine whether to use IPv4/IPv6
8049 @subsubsection X Window
8051 Support for the X Window graphical display system---specifically
8052 Xorg---is provided by the @code{(gnu services xorg)} module. Note that
8053 there is no @code{xorg-service} procedure. Instead, the X server is
8054 started by the @dfn{login manager}, currently SLiM.
8056 @deffn {Scheme Procedure} slim-service [#:allow-empty-passwords? #f] @
8057 [#:auto-login? #f] [#:default-user ""] [#:startx] @
8058 [#:theme @var{%default-slim-theme}] @
8059 [#:theme-name @var{%default-slim-theme-name}]
8060 Return a service that spawns the SLiM graphical login manager, which in
8061 turn starts the X display server with @var{startx}, a command as returned by
8062 @code{xorg-start-command}.
8066 SLiM automatically looks for session types described by the @file{.desktop}
8067 files in @file{/run/current-system/profile/share/xsessions} and allows users
8068 to choose a session from the log-in screen using @kbd{F1}. Packages such as
8069 @var{xfce}, @var{sawfish}, and @var{ratpoison} provide @file{.desktop} files;
8070 adding them to the system-wide set of packages automatically makes them
8071 available at the log-in screen.
8073 In addition, @file{~/.xsession} files are honored. When available,
8074 @file{~/.xsession} must be an executable that starts a window manager
8075 and/or other X clients.
8077 When @var{allow-empty-passwords?} is true, allow logins with an empty
8078 password. When @var{auto-login?} is true, log in automatically as
8081 If @var{theme} is @code{#f}, use the default log-in theme; otherwise
8082 @var{theme} must be a gexp denoting the name of a directory containing the
8083 theme to use. In that case, @var{theme-name} specifies the name of the
8087 @defvr {Scheme Variable} %default-theme
8088 @defvrx {Scheme Variable} %default-theme-name
8089 The G-Expression denoting the default SLiM theme and its name.
8092 @deffn {Scheme Procedure} xorg-start-command [#:guile] @
8093 [#:configuration-file #f] [#:xorg-server @var{xorg-server}]
8094 Return a derivation that builds a @var{guile} script to start the X server
8095 from @var{xorg-server}. @var{configuration-file} is the server configuration
8096 file or a derivation that builds it; when omitted, the result of
8097 @code{xorg-configuration-file} is used.
8099 Usually the X server is started by a login manager.
8102 @deffn {Scheme Procedure} xorg-configuration-file @
8103 [#:drivers '()] [#:resolutions '()] [#:extra-config '()]
8104 Return a configuration file for the Xorg server containing search paths for
8105 all the common drivers.
8107 @var{drivers} must be either the empty list, in which case Xorg chooses a
8108 graphics driver automatically, or a list of driver names that will be tried in
8109 this order---e.g., @code{(\"modesetting\" \"vesa\")}.
8111 Likewise, when @var{resolutions} is the empty list, Xorg chooses an
8112 appropriate screen resolution; otherwise, it must be a list of
8113 resolutions---e.g., @code{((1024 768) (640 480))}.
8115 Last, @var{extra-config} is a list of strings or objects appended to the
8116 @code{text-file*} argument list. It is used to pass extra text to be added
8117 verbatim to the configuration file.
8120 @deffn {Scheme Procedure} screen-locker-service @var{package} [@var{name}]
8121 Add @var{package}, a package for a screen-locker or screen-saver whose
8122 command is @var{program}, to the set of setuid programs and add a PAM entry
8123 for it. For example:
8126 (screen-locker-service xlockmore "xlock")
8129 makes the good ol' XlockMore usable.
8133 @node Desktop Services
8134 @subsubsection Desktop Services
8136 The @code{(gnu services desktop)} module provides services that are
8137 usually useful in the context of a ``desktop'' setup---that is, on a
8138 machine running a graphical display server, possibly with graphical user
8139 interfaces, etc. It also defines services that provide specific desktop
8140 environments like GNOME and XFCE.
8142 To simplify things, the module defines a variable containing the set of
8143 services that users typically expect on a machine with a graphical
8144 environment and networking:
8146 @defvr {Scheme Variable} %desktop-services
8147 This is a list of services that builds upon @var{%base-services} and
8148 adds or adjusts services for a typical ``desktop'' setup.
8150 In particular, it adds a graphical login manager (@pxref{X Window,
8151 @code{slim-service}}), screen lockers,
8152 a network management tool (@pxref{Networking
8153 Services, @code{wicd-service}}), energy and color management services,
8154 the @code{elogind} login and seat manager, the Polkit privilege service,
8155 the GeoClue location service, an NTP client (@pxref{Networking
8156 Services}), the Avahi daemon, and has the name service switch service
8157 configured to be able to use @code{nss-mdns} (@pxref{Name Service
8161 The @var{%desktop-services} variable can be used as the @code{services}
8162 field of an @code{operating-system} declaration (@pxref{operating-system
8163 Reference, @code{services}}).
8165 Additionally, the @code{gnome-desktop-service} and
8166 @code{xfce-desktop-service} procedures can add GNOME and/or XFCE to a
8167 system. To ``add GNOME'' means that system-level services like the
8168 backlight adjustment helpers and the power management utilities are
8169 added to the system, extending @code{polkit} and @code{dbus}
8170 appropriately, allowing GNOME to operate with elevated privileges on a
8171 limited number of special-purpose system interfaces. Additionally,
8172 adding a service made by @code{gnome-desktop-service} adds the GNOME
8173 metapackage to the system profile. Likewise, adding the XFCE service
8174 not only adds the @code{xfce} metapackage to the system profile, but it
8175 also gives the Thunar file manager the ability to open a ``root-mode''
8176 file management window, if the user authenticates using the
8177 administrator's password via the standard polkit graphical interface.
8179 @deffn {Scheme Procedure} gnome-desktop-service
8180 Return a service that adds the @code{gnome} package to the system
8181 profile, and extends polkit with the actions from
8182 @code{gnome-settings-daemon}.
8185 @deffn {Scheme Procedure} xfce-desktop-service
8186 Return a service that adds the @code{xfce} package to the system profile,
8187 and extends polkit with the abilit for @code{thunar} to manipulate the
8188 file system as root from within a user session, after the user has
8189 authenticated with the administrator's password.
8192 Because the GNOME and XFCE desktop services pull in so many packages,
8193 the default @code{%desktop-services} variable doesn't include either of
8194 them by default. To add GNOME or XFCE, just @code{cons} them onto
8195 @code{%desktop-services} in the @code{services} field of your
8196 @code{operating-system}:
8200 (use-service-modules desktop)
8203 ;; cons* adds items to the list given as its last argument.
8204 (services (cons* (gnome-desktop-service)
8205 (xfce-desktop-service)
8210 These desktop environments will then be available as options in the
8211 graphical login window.
8213 The actual service definitions included in @code{%desktop-services} and
8214 provided by @code{(gnu services dbus)} and @code{(gnu services desktop)}
8215 are described below.
8217 @deffn {Scheme Procedure} dbus-service [#:dbus @var{dbus}] [#:services '()]
8218 Return a service that runs the ``system bus'', using @var{dbus}, with
8219 support for @var{services}.
8221 @uref{http://dbus.freedesktop.org/, D-Bus} is an inter-process communication
8222 facility. Its system bus is used to allow system services to communicate
8223 and to be notified of system-wide events.
8225 @var{services} must be a list of packages that provide an
8226 @file{etc/dbus-1/system.d} directory containing additional D-Bus configuration
8227 and policy files. For example, to allow avahi-daemon to use the system bus,
8228 @var{services} must be equal to @code{(list avahi)}.
8231 @deffn {Scheme Procedure} elogind-service [#:config @var{config}]
8232 Return a service that runs the @code{elogind} login and
8233 seat management daemon. @uref{https://github.com/andywingo/elogind,
8234 Elogind} exposes a D-Bus interface that can be used to know which users
8235 are logged in, know what kind of sessions they have open, suspend the
8236 system, inhibit system suspend, reboot the system, and other tasks.
8238 Elogind handles most system-level power events for a computer, for
8239 example suspending the system when a lid is closed, or shutting it down
8240 when the power button is pressed.
8242 The @var{config} keyword argument specifies the configuration for
8243 elogind, and should be the result of an @code{(elogind-configuration
8244 (@var{parameter} @var{value})...)} invocation. Available parameters and
8245 their default values are:
8248 @item kill-user-processes?
8250 @item kill-only-users
8252 @item kill-exclude-users
8254 @item inhibit-delay-max-seconds
8256 @item handle-power-key
8258 @item handle-suspend-key
8260 @item handle-hibernate-key
8262 @item handle-lid-switch
8264 @item handle-lid-switch-docked
8266 @item power-key-ignore-inhibited?
8268 @item suspend-key-ignore-inhibited?
8270 @item hibernate-key-ignore-inhibited?
8272 @item lid-switch-ignore-inhibited?
8274 @item holdoff-timeout-seconds
8278 @item idle-action-seconds
8280 @item runtime-directory-size-percent
8282 @item runtime-directory-size
8287 @code{("mem" "standby" "freeze")}
8290 @item hibernate-state
8292 @item hibernate-mode
8293 @code{("platform" "shutdown")}
8294 @item hybrid-sleep-state
8296 @item hybrid-sleep-mode
8297 @code{("suspend" "platform" "shutdown")}
8301 @deffn {Scheme Procedure} polkit-service @
8302 [#:polkit @var{polkit}]
8303 Return a service that runs the
8304 @uref{http://www.freedesktop.org/wiki/Software/polkit/, Polkit privilege
8305 management service}, which allows system administrators to grant access to
8306 privileged operations in a structured way. By querying the Polkit service, a
8307 privileged system component can know when it should grant additional
8308 capabilities to ordinary users. For example, an ordinary user can be granted
8309 the capability to suspend the system if the user is logged in locally.
8312 @deffn {Scheme Procedure} upower-service [#:upower @var{upower}] @
8313 [#:watts-up-pro? #f] @
8314 [#:poll-batteries? #t] @
8315 [#:ignore-lid? #f] @
8316 [#:use-percentage-for-policy? #f] @
8317 [#:percentage-low 10] @
8318 [#:percentage-critical 3] @
8319 [#:percentage-action 2] @
8321 [#:time-critical 300] @
8322 [#:time-action 120] @
8323 [#:critical-power-action 'hybrid-sleep]
8324 Return a service that runs @uref{http://upower.freedesktop.org/,
8325 @command{upowerd}}, a system-wide monitor for power consumption and battery
8326 levels, with the given configuration settings. It implements the
8327 @code{org.freedesktop.UPower} D-Bus interface, and is notably used by
8331 @deffn {Scheme Procedure} udisks-service [#:udisks @var{udisks}]
8332 Return a service for @uref{http://udisks.freedesktop.org/docs/latest/,
8333 UDisks}, a @dfn{disk management} daemon that provides user interfaces with
8334 notifications and ways to mount/unmount disks. Programs that talk to UDisks
8335 include the @command{udisksctl} command, part of UDisks, and GNOME Disks.
8338 @deffn {Scheme Procedure} colord-service [#:colord @var{colord}]
8339 Return a service that runs @command{colord}, a system service with a D-Bus
8340 interface to manage the color profiles of input and output devices such as
8341 screens and scanners. It is notably used by the GNOME Color Manager graphical
8342 tool. See @uref{http://www.freedesktop.org/software/colord/, the colord web
8343 site} for more information.
8346 @deffn {Scheme Procedure} geoclue-application name [#:allowed? #t] [#:system? #f] [#:users '()]
8347 Return a configuration allowing an application to access GeoClue
8348 location data. @var{name} is the Desktop ID of the application, without
8349 the @code{.desktop} part. If @var{allowed?} is true, the application
8350 will have access to location information by default. The boolean
8351 @var{system?} value indicates whether an application is a system component
8352 or not. Finally @var{users} is a list of UIDs of all users for which
8353 this application is allowed location info access. An empty users list
8354 means that all users are allowed.
8357 @defvr {Scheme Variable} %standard-geoclue-applications
8358 The standard list of well-known GeoClue application configurations,
8359 granting authority to the GNOME date-and-time utility to ask for the
8360 current location in order to set the time zone, and allowing the
8361 IceCat and Epiphany web browsers to request location information.
8362 IceCat and Epiphany both query the user before allowing a web page to
8363 know the user's location.
8366 @deffn {Scheme Procedure} geoclue-service [#:colord @var{colord}] @
8368 [#:wifi-geolocation-url "https://location.services.mozilla.com/v1/geolocate?key=geoclue"] @
8370 [#:wifi-submission-url "https://location.services.mozilla.com/v1/submit?key=geoclue"] @
8371 [#:submission-nick "geoclue"] @
8372 [#:applications %standard-geoclue-applications]
8373 Return a service that runs the GeoClue location service. This service
8374 provides a D-Bus interface to allow applications to request access to a
8375 user's physical location, and optionally to add information to online
8376 location databases. See
8377 @uref{https://wiki.freedesktop.org/www/Software/GeoClue/, the GeoClue
8378 web site} for more information.
8381 @deffn {Scheme Procedure} bluetooth-service [#:bluez @var{bluez}]
8382 Return a service that runs the @command{bluetoothd} daemon, which manages
8383 all the Bluetooth devices and provides a number of D-Bus interfaces.
8385 Users need to be in the @code{lp} group to access the D-Bus service.
8388 @node Database Services
8389 @subsubsection Database Services
8391 The @code{(gnu services databases)} module provides the following services.
8393 @deffn {Scheme Procedure} postgresql-service [#:postgresql postgresql] @
8394 [#:config-file] [#:data-directory ``/var/lib/postgresql/data'']
8395 Return a service that runs @var{postgresql}, the PostgreSQL database
8398 The PostgreSQL daemon loads its runtime configuration from
8399 @var{config-file} and stores the database cluster in
8400 @var{data-directory}.
8403 @deffn {Scheme Procedure} mysql-service [#:config (mysql-configuration)]
8404 Return a service that runs @command{mysqld}, the MySQL or MariaDB
8407 The optional @var{config} argument specifies the configuration for
8408 @command{mysqld}, which should be a @code{<mysql-configuraiton>} object.
8411 @deftp {Data Type} mysql-configuration
8412 Data type representing the configuration of @var{mysql-service}.
8415 @item @code{mysql} (default: @var{mariadb})
8416 Package object of the MySQL database server, can be either @var{mariadb}
8419 For MySQL, a temorary root password will be displayed at activation time.
8420 For MariaDB, the root password is empty.
8425 @subsubsection Mail Services
8427 The @code{(gnu services mail)} module provides Guix service definitions
8428 for mail services. Currently the only implemented service is Dovecot,
8429 an IMAP, POP3, and LMTP server.
8431 Guix does not yet have a mail transfer agent (MTA), although for some
8432 lightweight purposes the @code{esmtp} relay-only MTA may suffice. Help
8433 is needed to properly integrate a full MTA, such as Postfix. Patches
8436 To add an IMAP/POP3 server to a GuixSD system, add a
8437 @code{dovecot-service} to the operating system definition:
8439 @deffn {Scheme Procedure} dovecot-service [#:config (dovecot-configuration)]
8440 Return a service that runs the Dovecot IMAP/POP3/LMTP mail server.
8443 By default, Dovecot does not need much configuration; the default
8444 configuration object created by @code{(dovecot-configuration)} will
8445 suffice if your mail is delivered to @code{~/Maildir}. A self-signed
8446 certificate will be generated for TLS-protected connections, though
8447 Dovecot will also listen on cleartext ports by default. There are a
8448 number of options, though, which mail administrators might need to change,
8449 and as is the case with other services, Guix allows the system
8450 administrator to specify these parameters via a uniform Scheme interface.
8452 For example, to specify that mail is located at @code{maildir~/.mail},
8453 one would instantiate the Dovecot service like this:
8456 (dovecot-service #:config
8457 (dovecot-configuration
8458 (mail-location "maildir:~/.mail")))
8461 The available configuration parameters follow. Each parameter
8462 definition is preceded by its type; for example, @samp{string-list foo}
8463 indicates that the @code{foo} parameter should be specified as a list of
8464 strings. There is also a way to specify the configuration as a string,
8465 if you have an old @code{dovecot.conf} file that you want to port over
8466 from some other system; see the end for more details.
8468 @c The following documentation was initially generated by
8469 @c (generate-documentation) in (gnu services mail). Manually maintained
8470 @c documentation is better, so we shouldn't hesitate to edit below as
8471 @c needed. However if the change you want to make to this documentation
8472 @c can be done in an automated way, it's probably easier to change
8473 @c (generate-documentation) than to make it below and have to deal with
8474 @c the churn as dovecot updates.
8476 Available @code{dovecot-configuration} fields are:
8478 @deftypevr {@code{dovecot-configuration} parameter} package dovecot
8479 The dovecot package.
8482 @deftypevr {@code{dovecot-configuration} parameter} comma-separated-string-list listen
8483 A list of IPs or hosts where to listen for connections. @samp{*}
8484 listens on all IPv4 interfaces, @samp{::} listens on all IPv6
8485 interfaces. If you want to specify non-default ports or anything more
8486 complex, customize the address and port fields of the
8487 @samp{inet-listener} of the specific services you are interested in.
8490 @deftypevr {@code{dovecot-configuration} parameter} protocol-configuration-list protocols
8491 List of protocols we want to serve. Available protocols include
8492 @samp{imap}, @samp{pop3}, and @samp{lmtp}.
8494 Available @code{protocol-configuration} fields are:
8496 @deftypevr {@code{protocol-configuration} parameter} string name
8497 The name of the protocol.
8500 @deftypevr {@code{protocol-configuration} parameter} string auth-socket-path
8501 UNIX socket path to the master authentication server to find users.
8502 This is used by imap (for shared users) and lda.
8503 It defaults to @samp{"/var/run/dovecot/auth-userdb"}.
8506 @deftypevr {@code{protocol-configuration} parameter} space-separated-string-list mail-plugins
8507 Space separated list of plugins to load.
8510 @deftypevr {@code{protocol-configuration} parameter} non-negative-integer mail-max-userip-connections
8511 Maximum number of IMAP connections allowed for a user from each IP
8512 address. NOTE: The username is compared case-sensitively.
8513 Defaults to @samp{10}.
8518 @deftypevr {@code{dovecot-configuration} parameter} service-configuration-list services
8519 List of services to enable. Available services include @samp{imap},
8520 @samp{imap-login}, @samp{pop3}, @samp{pop3-login}, @samp{auth}, and
8523 Available @code{service-configuration} fields are:
8525 @deftypevr {@code{service-configuration} parameter} string kind
8526 The service kind. Valid values include @code{director},
8527 @code{imap-login}, @code{pop3-login}, @code{lmtp}, @code{imap},
8528 @code{pop3}, @code{auth}, @code{auth-worker}, @code{dict},
8529 @code{tcpwrap}, @code{quota-warning}, or anything else.
8532 @deftypevr {@code{service-configuration} parameter} listener-configuration-list listeners
8533 Listeners for the service. A listener is either a
8534 @code{unix-listener-configuration}, a @code{fifo-listener-configuration}, or
8535 an @code{inet-listener-configuration}.
8536 Defaults to @samp{()}.
8538 Available @code{unix-listener-configuration} fields are:
8540 @deftypevr {@code{unix-listener-configuration} parameter} file-name path
8541 The file name on which to listen.
8544 @deftypevr {@code{unix-listener-configuration} parameter} string mode
8545 The access mode for the socket.
8546 Defaults to @samp{"0600"}.
8549 @deftypevr {@code{unix-listener-configuration} parameter} string user
8550 The user to own the socket.
8551 Defaults to @samp{""}.
8554 @deftypevr {@code{unix-listener-configuration} parameter} string group
8555 The group to own the socket.
8556 Defaults to @samp{""}.
8560 Available @code{fifo-listener-configuration} fields are:
8562 @deftypevr {@code{fifo-listener-configuration} parameter} file-name path
8563 The file name on which to listen.
8566 @deftypevr {@code{fifo-listener-configuration} parameter} string mode
8567 The access mode for the socket.
8568 Defaults to @samp{"0600"}.
8571 @deftypevr {@code{fifo-listener-configuration} parameter} string user
8572 The user to own the socket.
8573 Defaults to @samp{""}.
8576 @deftypevr {@code{fifo-listener-configuration} parameter} string group
8577 The group to own the socket.
8578 Defaults to @samp{""}.
8582 Available @code{inet-listener-configuration} fields are:
8584 @deftypevr {@code{inet-listener-configuration} parameter} string protocol
8585 The protocol to listen for.
8588 @deftypevr {@code{inet-listener-configuration} parameter} string address
8589 The address on which to listen, or empty for all addresses.
8590 Defaults to @samp{""}.
8593 @deftypevr {@code{inet-listener-configuration} parameter} non-negative-integer port
8594 The port on which to listen.
8597 @deftypevr {@code{inet-listener-configuration} parameter} boolean ssl?
8598 Whether to use SSL for this service; @samp{yes}, @samp{no}, or
8600 Defaults to @samp{#t}.
8605 @deftypevr {@code{service-configuration} parameter} non-negative-integer service-count
8606 Number of connections to handle before starting a new process.
8607 Typically the only useful values are 0 (unlimited) or 1. 1 is more
8608 secure, but 0 is faster. <doc/wiki/LoginProcess.txt>.
8609 Defaults to @samp{1}.
8612 @deftypevr {@code{service-configuration} parameter} non-negative-integer process-min-avail
8613 Number of processes to always keep waiting for more connections.
8614 Defaults to @samp{0}.
8617 @deftypevr {@code{service-configuration} parameter} non-negative-integer vsz-limit
8618 If you set @samp{service-count 0}, you probably need to grow
8620 Defaults to @samp{256000000}.
8625 @deftypevr {@code{dovecot-configuration} parameter} dict-configuration dict
8626 Dict configuration, as created by the @code{dict-configuration}
8629 Available @code{dict-configuration} fields are:
8631 @deftypevr {@code{dict-configuration} parameter} free-form-fields entries
8632 A list of key-value pairs that this dict should hold.
8633 Defaults to @samp{()}.
8638 @deftypevr {@code{dovecot-configuration} parameter} passdb-configuration-list passdbs
8639 A list of passdb configurations, each one created by the
8640 @code{passdb-configuration} constructor.
8642 Available @code{passdb-configuration} fields are:
8644 @deftypevr {@code{passdb-configuration} parameter} string driver
8645 The driver that the passdb should use. Valid values include
8646 @samp{pam}, @samp{passwd}, @samp{shadow}, @samp{bsdauth}, and
8648 Defaults to @samp{"pam"}.
8651 @deftypevr {@code{passdb-configuration} parameter} free-form-args args
8652 A list of key-value args to the passdb driver.
8653 Defaults to @samp{()}.
8658 @deftypevr {@code{dovecot-configuration} parameter} userdb-configuration-list userdbs
8659 List of userdb configurations, each one created by the
8660 @code{userdb-configuration} constructor.
8662 Available @code{userdb-configuration} fields are:
8664 @deftypevr {@code{userdb-configuration} parameter} string driver
8665 The driver that the userdb should use. Valid values include
8666 @samp{passwd} and @samp{static}.
8667 Defaults to @samp{"passwd"}.
8670 @deftypevr {@code{userdb-configuration} parameter} free-form-args args
8671 A list of key-value args to the userdb driver.
8672 Defaults to @samp{()}.
8675 @deftypevr {@code{userdb-configuration} parameter} free-form-args override-fields
8676 Override fields from passwd.
8677 Defaults to @samp{()}.
8682 @deftypevr {@code{dovecot-configuration} parameter} plugin-configuration plugin-configuration
8683 Plug-in configuration, created by the @code{plugin-configuration}
8687 @deftypevr {@code{dovecot-configuration} parameter} list-of-namespace-configuration namespaces
8688 List of namespaces. Each item in the list is created by the
8689 @code{namespace-configuration} constructor.
8691 Available @code{namespace-configuration} fields are:
8693 @deftypevr {@code{namespace-configuration} parameter} string name
8694 Name for this namespace.
8697 @deftypevr {@code{namespace-configuration} parameter} string type
8698 Namespace type: @samp{private}, @samp{shared} or @samp{public}.
8699 Defaults to @samp{"private"}.
8702 @deftypevr {@code{namespace-configuration} parameter} string separator
8703 Hierarchy separator to use. You should use the same separator for
8704 all namespaces or some clients get confused. @samp{/} is usually a good
8705 one. The default however depends on the underlying mail storage
8707 Defaults to @samp{""}.
8710 @deftypevr {@code{namespace-configuration} parameter} string prefix
8711 Prefix required to access this namespace. This needs to be
8712 different for all namespaces. For example @samp{Public/}.
8713 Defaults to @samp{""}.
8716 @deftypevr {@code{namespace-configuration} parameter} string location
8717 Physical location of the mailbox. This is in the same format as
8718 mail_location, which is also the default for it.
8719 Defaults to @samp{""}.
8722 @deftypevr {@code{namespace-configuration} parameter} boolean inbox?
8723 There can be only one INBOX, and this setting defines which
8725 Defaults to @samp{#f}.
8728 @deftypevr {@code{namespace-configuration} parameter} boolean hidden?
8729 If namespace is hidden, it's not advertised to clients via NAMESPACE
8730 extension. You'll most likely also want to set @samp{list? #f}. This is mostly
8731 useful when converting from another server with different namespaces
8732 which you want to deprecate but still keep working. For example you can
8733 create hidden namespaces with prefixes @samp{~/mail/}, @samp{~%u/mail/}
8735 Defaults to @samp{#f}.
8738 @deftypevr {@code{namespace-configuration} parameter} boolean list?
8739 Show the mailboxes under this namespace with the LIST command. This
8740 makes the namespace visible for clients that do not support the NAMESPACE
8741 extension. The special @code{children} value lists child mailboxes, but
8742 hides the namespace prefix.
8743 Defaults to @samp{#t}.
8746 @deftypevr {@code{namespace-configuration} parameter} boolean subscriptions?
8747 Namespace handles its own subscriptions. If set to @code{#f}, the
8748 parent namespace handles them. The empty prefix should always have this
8750 Defaults to @samp{#t}.
8753 @deftypevr {@code{namespace-configuration} parameter} mailbox-configuration-list mailboxes
8754 List of predefined mailboxes in this namespace.
8755 Defaults to @samp{()}.
8757 Available @code{mailbox-configuration} fields are:
8759 @deftypevr {@code{mailbox-configuration} parameter} string name
8760 Name for this mailbox.
8763 @deftypevr {@code{mailbox-configuration} parameter} string auto
8764 @samp{create} will automatically create this mailbox.
8765 @samp{subscribe} will both create and subscribe to the mailbox.
8766 Defaults to @samp{"no"}.
8769 @deftypevr {@code{mailbox-configuration} parameter} space-separated-string-list special-use
8770 List of IMAP @code{SPECIAL-USE} attributes as specified by RFC 6154.
8771 Valid values are @code{\All}, @code{\Archive}, @code{\Drafts},
8772 @code{\Flagged}, @code{\Junk}, @code{\Sent}, and @code{\Trash}.
8773 Defaults to @samp{()}.
8780 @deftypevr {@code{dovecot-configuration} parameter} file-name base-dir
8781 Base directory where to store runtime data.
8782 Defaults to @samp{"/var/run/dovecot/"}.
8785 @deftypevr {@code{dovecot-configuration} parameter} string login-greeting
8786 Greeting message for clients.
8787 Defaults to @samp{"Dovecot ready."}.
8790 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-trusted-networks
8791 List of trusted network ranges. Connections from these IPs are
8792 allowed to override their IP addresses and ports (for logging and for
8793 authentication checks). @samp{disable-plaintext-auth} is also ignored
8794 for these networks. Typically you would specify your IMAP proxy servers
8796 Defaults to @samp{()}.
8799 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-access-sockets
8800 List of login access check sockets (e.g. tcpwrap).
8801 Defaults to @samp{()}.
8804 @deftypevr {@code{dovecot-configuration} parameter} boolean verbose-proctitle?
8805 Show more verbose process titles (in ps). Currently shows user name
8806 and IP address. Useful for seeing who is actually using the IMAP
8807 processes (e.g. shared mailboxes or if the same uid is used for multiple
8809 Defaults to @samp{#f}.
8812 @deftypevr {@code{dovecot-configuration} parameter} boolean shutdown-clients?
8813 Should all processes be killed when Dovecot master process shuts down.
8814 Setting this to @code{#f} means that Dovecot can be upgraded without
8815 forcing existing client connections to close (although that could also
8816 be a problem if the upgrade is e.g. due to a security fix).
8817 Defaults to @samp{#t}.
8820 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer doveadm-worker-count
8821 If non-zero, run mail commands via this many connections to doveadm
8822 server, instead of running them directly in the same process.
8823 Defaults to @samp{0}.
8826 @deftypevr {@code{dovecot-configuration} parameter} string doveadm-socket-path
8827 UNIX socket or host:port used for connecting to doveadm server.
8828 Defaults to @samp{"doveadm-server"}.
8831 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list import-environment
8832 List of environment variables that are preserved on Dovecot startup
8833 and passed down to all of its child processes. You can also give
8834 key=value pairs to always set specific settings.
8837 @deftypevr {@code{dovecot-configuration} parameter} boolean disable-plaintext-auth?
8838 Disable LOGIN command and all other plaintext authentications unless
8839 SSL/TLS is used (LOGINDISABLED capability). Note that if the remote IP
8840 matches the local IP (i.e. you're connecting from the same computer),
8841 the connection is considered secure and plaintext authentication is
8842 allowed. See also ssl=required setting.
8843 Defaults to @samp{#t}.
8846 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer auth-cache-size
8847 Authentication cache size (e.g. @samp{#e10e6}). 0 means it's disabled.
8848 Note that bsdauth, PAM and vpopmail require @samp{cache-key} to be set
8849 for caching to be used.
8850 Defaults to @samp{0}.
8853 @deftypevr {@code{dovecot-configuration} parameter} string auth-cache-ttl
8854 Time to live for cached data. After TTL expires the cached record
8855 is no longer used, *except* if the main database lookup returns internal
8856 failure. We also try to handle password changes automatically: If
8857 user's previous authentication was successful, but this one wasn't, the
8858 cache isn't used. For now this works only with plaintext
8860 Defaults to @samp{"1 hour"}.
8863 @deftypevr {@code{dovecot-configuration} parameter} string auth-cache-negative-ttl
8864 TTL for negative hits (user not found, password mismatch).
8865 0 disables caching them completely.
8866 Defaults to @samp{"1 hour"}.
8869 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list auth-realms
8870 List of realms for SASL authentication mechanisms that need them.
8871 You can leave it empty if you don't want to support multiple realms.
8872 Many clients simply use the first one listed here, so keep the default
8874 Defaults to @samp{()}.
8877 @deftypevr {@code{dovecot-configuration} parameter} string auth-default-realm
8878 Default realm/domain to use if none was specified. This is used for
8879 both SASL realms and appending @@domain to username in plaintext
8881 Defaults to @samp{""}.
8884 @deftypevr {@code{dovecot-configuration} parameter} string auth-username-chars
8885 List of allowed characters in username. If the user-given username
8886 contains a character not listed in here, the login automatically fails.
8887 This is just an extra check to make sure user can't exploit any
8888 potential quote escaping vulnerabilities with SQL/LDAP databases. If
8889 you want to allow all characters, set this value to empty.
8890 Defaults to @samp{"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890.-_@@"}.
8893 @deftypevr {@code{dovecot-configuration} parameter} string auth-username-translation
8894 Username character translations before it's looked up from
8895 databases. The value contains series of from -> to characters. For
8896 example @samp{#@@/@@} means that @samp{#} and @samp{/} characters are
8897 translated to @samp{@@}.
8898 Defaults to @samp{""}.
8901 @deftypevr {@code{dovecot-configuration} parameter} string auth-username-format
8902 Username formatting before it's looked up from databases. You can
8903 use the standard variables here, e.g. %Lu would lowercase the username,
8904 %n would drop away the domain if it was given, or @samp{%n-AT-%d} would
8905 change the @samp{@@} into @samp{-AT-}. This translation is done after
8906 @samp{auth-username-translation} changes.
8907 Defaults to @samp{"%Lu"}.
8910 @deftypevr {@code{dovecot-configuration} parameter} string auth-master-user-separator
8911 If you want to allow master users to log in by specifying the master
8912 username within the normal username string (i.e. not using SASL
8913 mechanism's support for it), you can specify the separator character
8914 here. The format is then <username><separator><master username>.
8915 UW-IMAP uses @samp{*} as the separator, so that could be a good
8917 Defaults to @samp{""}.
8920 @deftypevr {@code{dovecot-configuration} parameter} string auth-anonymous-username
8921 Username to use for users logging in with ANONYMOUS SASL
8923 Defaults to @samp{"anonymous"}.
8926 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer auth-worker-max-count
8927 Maximum number of dovecot-auth worker processes. They're used to
8928 execute blocking passdb and userdb queries (e.g. MySQL and PAM).
8929 They're automatically created and destroyed as needed.
8930 Defaults to @samp{30}.
8933 @deftypevr {@code{dovecot-configuration} parameter} string auth-gssapi-hostname
8934 Host name to use in GSSAPI principal names. The default is to use
8935 the name returned by gethostname(). Use @samp{$ALL} (with quotes) to
8936 allow all keytab entries.
8937 Defaults to @samp{""}.
8940 @deftypevr {@code{dovecot-configuration} parameter} string auth-krb5-keytab
8941 Kerberos keytab to use for the GSSAPI mechanism. Will use the
8942 system default (usually /etc/krb5.keytab) if not specified. You may
8943 need to change the auth service to run as root to be able to read this
8945 Defaults to @samp{""}.
8948 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-use-winbind?
8949 Do NTLM and GSS-SPNEGO authentication using Samba's winbind daemon
8950 and @samp{ntlm-auth} helper.
8951 <doc/wiki/Authentication/Mechanisms/Winbind.txt>.
8952 Defaults to @samp{#f}.
8955 @deftypevr {@code{dovecot-configuration} parameter} file-name auth-winbind-helper-path
8956 Path for Samba's @samp{ntlm-auth} helper binary.
8957 Defaults to @samp{"/usr/bin/ntlm_auth"}.
8960 @deftypevr {@code{dovecot-configuration} parameter} string auth-failure-delay
8961 Time to delay before replying to failed authentications.
8962 Defaults to @samp{"2 secs"}.
8965 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-ssl-require-client-cert?
8966 Require a valid SSL client certificate or the authentication
8968 Defaults to @samp{#f}.
8971 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-ssl-username-from-cert?
8972 Take the username from client's SSL certificate, using
8973 @code{X509_NAME_get_text_by_NID()} which returns the subject's DN's
8975 Defaults to @samp{#f}.
8978 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list auth-mechanisms
8979 List of wanted authentication mechanisms. Supported mechanisms are:
8980 @samp{plain}, @samp{login}, @samp{digest-md5}, @samp{cram-md5},
8981 @samp{ntlm}, @samp{rpa}, @samp{apop}, @samp{anonymous}, @samp{gssapi},
8982 @samp{otp}, @samp{skey}, and @samp{gss-spnego}. NOTE: See also
8983 @samp{disable-plaintext-auth} setting.
8986 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list director-servers
8987 List of IPs or hostnames to all director servers, including ourself.
8988 Ports can be specified as ip:port. The default port is the same as what
8989 director service's @samp{inet-listener} is using.
8990 Defaults to @samp{()}.
8993 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list director-mail-servers
8994 List of IPs or hostnames to all backend mail servers. Ranges are
8995 allowed too, like 10.0.0.10-10.0.0.30.
8996 Defaults to @samp{()}.
8999 @deftypevr {@code{dovecot-configuration} parameter} string director-user-expire
9000 How long to redirect users to a specific server after it no longer
9001 has any connections.
9002 Defaults to @samp{"15 min"}.
9005 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer director-doveadm-port
9006 TCP/IP port that accepts doveadm connections (instead of director
9007 connections) If you enable this, you'll also need to add
9008 @samp{inet-listener} for the port.
9009 Defaults to @samp{0}.
9012 @deftypevr {@code{dovecot-configuration} parameter} string director-username-hash
9013 How the username is translated before being hashed. Useful values
9014 include %Ln if user can log in with or without @@domain, %Ld if mailboxes
9015 are shared within domain.
9016 Defaults to @samp{"%Lu"}.
9019 @deftypevr {@code{dovecot-configuration} parameter} string log-path
9020 Log file to use for error messages. @samp{syslog} logs to syslog,
9021 @samp{/dev/stderr} logs to stderr.
9022 Defaults to @samp{"syslog"}.
9025 @deftypevr {@code{dovecot-configuration} parameter} string info-log-path
9026 Log file to use for informational messages. Defaults to
9028 Defaults to @samp{""}.
9031 @deftypevr {@code{dovecot-configuration} parameter} string debug-log-path
9032 Log file to use for debug messages. Defaults to
9033 @samp{info-log-path}.
9034 Defaults to @samp{""}.
9037 @deftypevr {@code{dovecot-configuration} parameter} string syslog-facility
9038 Syslog facility to use if you're logging to syslog. Usually if you
9039 don't want to use @samp{mail}, you'll use local0..local7. Also other
9040 standard facilities are supported.
9041 Defaults to @samp{"mail"}.
9044 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-verbose?
9045 Log unsuccessful authentication attempts and the reasons why they
9047 Defaults to @samp{#f}.
9050 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-verbose-passwords?
9051 In case of password mismatches, log the attempted password. Valid
9052 values are no, plain and sha1. sha1 can be useful for detecting brute
9053 force password attempts vs. user simply trying the same password over
9054 and over again. You can also truncate the value to n chars by appending
9056 Defaults to @samp{#f}.
9059 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-debug?
9060 Even more verbose logging for debugging purposes. Shows for example
9062 Defaults to @samp{#f}.
9065 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-debug-passwords?
9066 In case of password mismatches, log the passwords and used scheme so
9067 the problem can be debugged. Enabling this also enables
9069 Defaults to @samp{#f}.
9072 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-debug?
9073 Enable mail process debugging. This can help you figure out why
9074 Dovecot isn't finding your mails.
9075 Defaults to @samp{#f}.
9078 @deftypevr {@code{dovecot-configuration} parameter} boolean verbose-ssl?
9079 Show protocol level SSL errors.
9080 Defaults to @samp{#f}.
9083 @deftypevr {@code{dovecot-configuration} parameter} string log-timestamp
9084 Prefix for each line written to log file. % codes are in
9086 Defaults to @samp{"\"%b %d %H:%M:%S \""}.
9089 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-log-format-elements
9090 List of elements we want to log. The elements which have a
9091 non-empty variable value are joined together to form a comma-separated
9095 @deftypevr {@code{dovecot-configuration} parameter} string login-log-format
9096 Login log format. %s contains @samp{login-log-format-elements}
9097 string, %$ contains the data we want to log.
9098 Defaults to @samp{"%$: %s"}.
9101 @deftypevr {@code{dovecot-configuration} parameter} string mail-log-prefix
9102 Log prefix for mail processes. See doc/wiki/Variables.txt for list
9103 of possible variables you can use.
9104 Defaults to @samp{"\"%s(%u): \""}.
9107 @deftypevr {@code{dovecot-configuration} parameter} string deliver-log-format
9108 Format to use for logging mail deliveries. You can use variables:
9111 Delivery status message (e.g. @samp{saved to INBOX})
9123 Defaults to @samp{"msgid=%m: %$"}.
9126 @deftypevr {@code{dovecot-configuration} parameter} string mail-location
9127 Location for users' mailboxes. The default is empty, which means
9128 that Dovecot tries to find the mailboxes automatically. This won't work
9129 if the user doesn't yet have any mail, so you should explicitly tell
9130 Dovecot the full location.
9132 If you're using mbox, giving a path to the INBOX
9133 file (e.g. /var/mail/%u) isn't enough. You'll also need to tell Dovecot
9134 where the other mailboxes are kept. This is called the "root mail
9135 directory", and it must be the first path given in the
9136 @samp{mail-location} setting.
9138 There are a few special variables you can use, eg.:
9144 user part in user@@domain, same as %u if there's no domain
9146 domain part in user@@domain, empty if there's no domain
9151 See doc/wiki/Variables.txt for full list. Some examples:
9153 @item maildir:~/Maildir
9154 @item mbox:~/mail:INBOX=/var/mail/%u
9155 @item mbox:/var/mail/%d/%1n/%n:INDEX=/var/indexes/%d/%1n/%
9157 Defaults to @samp{""}.
9160 @deftypevr {@code{dovecot-configuration} parameter} string mail-uid
9161 System user and group used to access mails. If you use multiple,
9162 userdb can override these by returning uid or gid fields. You can use
9163 either numbers or names. <doc/wiki/UserIds.txt>.
9164 Defaults to @samp{""}.
9167 @deftypevr {@code{dovecot-configuration} parameter} string mail-gid
9169 Defaults to @samp{""}.
9172 @deftypevr {@code{dovecot-configuration} parameter} string mail-privileged-group
9173 Group to enable temporarily for privileged operations. Currently
9174 this is used only with INBOX when either its initial creation or
9175 dotlocking fails. Typically this is set to "mail" to give access to
9177 Defaults to @samp{""}.
9180 @deftypevr {@code{dovecot-configuration} parameter} string mail-access-groups
9181 Grant access to these supplementary groups for mail processes.
9182 Typically these are used to set up access to shared mailboxes. Note
9183 that it may be dangerous to set these if users can create
9184 symlinks (e.g. if "mail" group is set here, ln -s /var/mail ~/mail/var
9185 could allow a user to delete others' mailboxes, or ln -s
9186 /secret/shared/box ~/mail/mybox would allow reading it).
9187 Defaults to @samp{""}.
9190 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-full-filesystem-access?
9191 Allow full filesystem access to clients. There's no access checks
9192 other than what the operating system does for the active UID/GID. It
9193 works with both maildir and mboxes, allowing you to prefix mailboxes
9194 names with e.g. /path/ or ~user/.
9195 Defaults to @samp{#f}.
9198 @deftypevr {@code{dovecot-configuration} parameter} boolean mmap-disable?
9199 Don't use mmap() at all. This is required if you store indexes to
9200 shared filesystems (NFS or clustered filesystem).
9201 Defaults to @samp{#f}.
9204 @deftypevr {@code{dovecot-configuration} parameter} boolean dotlock-use-excl?
9205 Rely on @samp{O_EXCL} to work when creating dotlock files. NFS
9206 supports @samp{O_EXCL} since version 3, so this should be safe to use
9207 nowadays by default.
9208 Defaults to @samp{#t}.
9211 @deftypevr {@code{dovecot-configuration} parameter} string mail-fsync
9212 When to use fsync() or fdatasync() calls:
9215 Whenever necessary to avoid losing important data
9217 Useful with e.g. NFS when write()s are delayed
9219 Never use it (best performance, but crashes can lose data).
9221 Defaults to @samp{"optimized"}.
9224 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-nfs-storage?
9225 Mail storage exists in NFS. Set this to yes to make Dovecot flush
9226 NFS caches whenever needed. If you're using only a single mail server
9228 Defaults to @samp{#f}.
9231 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-nfs-index?
9232 Mail index files also exist in NFS. Setting this to yes requires
9233 @samp{mmap-disable? #t} and @samp{fsync-disable? #f}.
9234 Defaults to @samp{#f}.
9237 @deftypevr {@code{dovecot-configuration} parameter} string lock-method
9238 Locking method for index files. Alternatives are fcntl, flock and
9239 dotlock. Dotlocking uses some tricks which may create more disk I/O
9240 than other locking methods. NFS users: flock doesn't work, remember to
9241 change @samp{mmap-disable}.
9242 Defaults to @samp{"fcntl"}.
9245 @deftypevr {@code{dovecot-configuration} parameter} file-name mail-temp-dir
9246 Directory in which LDA/LMTP temporarily stores incoming mails >128
9248 Defaults to @samp{"/tmp"}.
9251 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer first-valid-uid
9252 Valid UID range for users. This is mostly to make sure that users can't
9253 log in as daemons or other system users. Note that denying root logins is
9254 hardcoded to dovecot binary and can't be done even if @samp{first-valid-uid}
9256 Defaults to @samp{500}.
9259 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer last-valid-uid
9261 Defaults to @samp{0}.
9264 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer first-valid-gid
9265 Valid GID range for users. Users having non-valid GID as primary group ID
9266 aren't allowed to log in. If user belongs to supplementary groups with
9267 non-valid GIDs, those groups are not set.
9268 Defaults to @samp{1}.
9271 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer last-valid-gid
9273 Defaults to @samp{0}.
9276 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-max-keyword-length
9277 Maximum allowed length for mail keyword name. It's only forced when
9278 trying to create new keywords.
9279 Defaults to @samp{50}.
9282 @deftypevr {@code{dovecot-configuration} parameter} colon-separated-file-name-list valid-chroot-dirs
9283 List of directories under which chrooting is allowed for mail
9284 processes (i.e. /var/mail will allow chrooting to /var/mail/foo/bar
9285 too). This setting doesn't affect @samp{login-chroot}
9286 @samp{mail-chroot} or auth chroot settings. If this setting is empty,
9287 "/./" in home dirs are ignored. WARNING: Never add directories here
9288 which local users can modify, that may lead to root exploit. Usually
9289 this should be done only if you don't allow shell access for users.
9290 <doc/wiki/Chrooting.txt>.
9291 Defaults to @samp{()}.
9294 @deftypevr {@code{dovecot-configuration} parameter} string mail-chroot
9295 Default chroot directory for mail processes. This can be overridden
9296 for specific users in user database by giving /./ in user's home
9297 directory (e.g. /home/./user chroots into /home). Note that usually
9298 there is no real need to do chrooting, Dovecot doesn't allow users to
9299 access files outside their mail directory anyway. If your home
9300 directories are prefixed with the chroot directory, append "/." to
9301 @samp{mail-chroot}. <doc/wiki/Chrooting.txt>.
9302 Defaults to @samp{""}.
9305 @deftypevr {@code{dovecot-configuration} parameter} file-name auth-socket-path
9306 UNIX socket path to master authentication server to find users.
9307 This is used by imap (for shared users) and lda.
9308 Defaults to @samp{"/var/run/dovecot/auth-userdb"}.
9311 @deftypevr {@code{dovecot-configuration} parameter} file-name mail-plugin-dir
9312 Directory where to look up mail plugins.
9313 Defaults to @samp{"/usr/lib/dovecot"}.
9316 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mail-plugins
9317 List of plugins to load for all services. Plugins specific to IMAP,
9318 LDA, etc. are added to this list in their own .conf files.
9319 Defaults to @samp{()}.
9322 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-cache-min-mail-count
9323 The minimum number of mails in a mailbox before updates are done to
9324 cache file. This allows optimizing Dovecot's behavior to do less disk
9325 writes at the cost of more disk reads.
9326 Defaults to @samp{0}.
9329 @deftypevr {@code{dovecot-configuration} parameter} string mailbox-idle-check-interval
9330 When IDLE command is running, mailbox is checked once in a while to
9331 see if there are any new mails or other changes. This setting defines
9332 the minimum time to wait between those checks. Dovecot can also use
9333 dnotify, inotify and kqueue to find out immediately when changes
9335 Defaults to @samp{"30 secs"}.
9338 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-save-crlf?
9339 Save mails with CR+LF instead of plain LF. This makes sending those
9340 mails take less CPU, especially with sendfile() syscall with Linux and
9341 FreeBSD. But it also creates a bit more disk I/O which may just make it
9342 slower. Also note that if other software reads the mboxes/maildirs,
9343 they may handle the extra CRs wrong and cause problems.
9344 Defaults to @samp{#f}.
9347 @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-stat-dirs?
9348 By default LIST command returns all entries in maildir beginning
9349 with a dot. Enabling this option makes Dovecot return only entries
9350 which are directories. This is done by stat()ing each entry, so it
9351 causes more disk I/O.
9352 (For systems setting struct @samp{dirent->d_type} this check is free
9353 and it's done always regardless of this setting).
9354 Defaults to @samp{#f}.
9357 @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-copy-with-hardlinks?
9358 When copying a message, do it with hard links whenever possible.
9359 This makes the performance much better, and it's unlikely to have any
9361 Defaults to @samp{#t}.
9364 @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-very-dirty-syncs?
9365 Assume Dovecot is the only MUA accessing Maildir: Scan cur/
9366 directory only when its mtime changes unexpectedly or when we can't find
9368 Defaults to @samp{#f}.
9371 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mbox-read-locks
9372 Which locking methods to use for locking mbox. There are four
9377 Create <mailbox>.lock file. This is the oldest and most NFS-safe
9378 solution. If you want to use /var/mail/ like directory, the users will
9379 need write access to that directory.
9381 Same as dotlock, but if it fails because of permissions or because there
9382 isn't enough disk space, just skip it.
9384 Use this if possible. Works with NFS too if lockd is used.
9386 May not exist in all systems. Doesn't work with NFS.
9388 May not exist in all systems. Doesn't work with NFS.
9391 You can use multiple locking methods; if you do the order they're declared
9392 in is important to avoid deadlocks if other MTAs/MUAs are using multiple
9393 locking methods as well. Some operating systems don't allow using some of
9394 them simultaneously.
9397 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mbox-write-locks
9401 @deftypevr {@code{dovecot-configuration} parameter} string mbox-lock-timeout
9402 Maximum time to wait for lock (all of them) before aborting.
9403 Defaults to @samp{"5 mins"}.
9406 @deftypevr {@code{dovecot-configuration} parameter} string mbox-dotlock-change-timeout
9407 If dotlock exists but the mailbox isn't modified in any way,
9408 override the lock file after this much time.
9409 Defaults to @samp{"2 mins"}.
9412 @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-dirty-syncs?
9413 When mbox changes unexpectedly we have to fully read it to find out
9414 what changed. If the mbox is large this can take a long time. Since
9415 the change is usually just a newly appended mail, it'd be faster to
9416 simply read the new mails. If this setting is enabled, Dovecot does
9417 this but still safely fallbacks to re-reading the whole mbox file
9418 whenever something in mbox isn't how it's expected to be. The only real
9419 downside to this setting is that if some other MUA changes message
9420 flags, Dovecot doesn't notice it immediately. Note that a full sync is
9421 done with SELECT, EXAMINE, EXPUNGE and CHECK commands.
9422 Defaults to @samp{#t}.
9425 @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-very-dirty-syncs?
9426 Like @samp{mbox-dirty-syncs}, but don't do full syncs even with SELECT,
9427 EXAMINE, EXPUNGE or CHECK commands. If this is set,
9428 @samp{mbox-dirty-syncs} is ignored.
9429 Defaults to @samp{#f}.
9432 @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-lazy-writes?
9433 Delay writing mbox headers until doing a full write sync (EXPUNGE
9434 and CHECK commands and when closing the mailbox). This is especially
9435 useful for POP3 where clients often delete all mails. The downside is
9436 that our changes aren't immediately visible to other MUAs.
9437 Defaults to @samp{#t}.
9440 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mbox-min-index-size
9441 If mbox size is smaller than this (e.g. 100k), don't write index
9442 files. If an index file already exists it's still read, just not
9444 Defaults to @samp{0}.
9447 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mdbox-rotate-size
9448 Maximum dbox file size until it's rotated.
9449 Defaults to @samp{2000000}.
9452 @deftypevr {@code{dovecot-configuration} parameter} string mdbox-rotate-interval
9453 Maximum dbox file age until it's rotated. Typically in days. Day
9454 begins from midnight, so 1d = today, 2d = yesterday, etc. 0 = check
9456 Defaults to @samp{"1d"}.
9459 @deftypevr {@code{dovecot-configuration} parameter} boolean mdbox-preallocate-space?
9460 When creating new mdbox files, immediately preallocate their size to
9461 @samp{mdbox-rotate-size}. This setting currently works only in Linux
9462 with some filesystems (ext4, xfs).
9463 Defaults to @samp{#f}.
9466 @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-dir
9467 sdbox and mdbox support saving mail attachments to external files,
9468 which also allows single instance storage for them. Other backends
9469 don't support this for now.
9471 WARNING: This feature hasn't been tested much yet. Use at your own risk.
9473 Directory root where to store mail attachments. Disabled, if empty.
9474 Defaults to @samp{""}.
9477 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-attachment-min-size
9478 Attachments smaller than this aren't saved externally. It's also
9479 possible to write a plugin to disable saving specific attachments
9481 Defaults to @samp{128000}.
9484 @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-fs
9485 Filesystem backend to use for saving attachments:
9488 No SiS done by Dovecot (but this might help FS's own deduplication)
9490 SiS with immediate byte-by-byte comparison during saving
9491 @item sis-queue posix
9492 SiS with delayed comparison and deduplication.
9494 Defaults to @samp{"sis posix"}.
9497 @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-hash
9498 Hash format to use in attachment filenames. You can add any text and
9499 variables: @code{%@{md4@}}, @code{%@{md5@}}, @code{%@{sha1@}},
9500 @code{%@{sha256@}}, @code{%@{sha512@}}, @code{%@{size@}}. Variables can be
9501 truncated, e.g. @code{%@{sha256:80@}} returns only first 80 bits.
9502 Defaults to @samp{"%@{sha1@}"}.
9505 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-process-limit
9507 Defaults to @samp{100}.
9510 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-client-limit
9512 Defaults to @samp{1000}.
9515 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-vsz-limit
9516 Default VSZ (virtual memory size) limit for service processes.
9517 This is mainly intended to catch and kill processes that leak memory
9518 before they eat up everything.
9519 Defaults to @samp{256000000}.
9522 @deftypevr {@code{dovecot-configuration} parameter} string default-login-user
9523 Login user is internally used by login processes. This is the most
9524 untrusted user in Dovecot system. It shouldn't have access to anything
9526 Defaults to @samp{"dovenull"}.
9529 @deftypevr {@code{dovecot-configuration} parameter} string default-internal-user
9530 Internal user is used by unprivileged processes. It should be
9531 separate from login user, so that login processes can't disturb other
9533 Defaults to @samp{"dovecot"}.
9536 @deftypevr {@code{dovecot-configuration} parameter} string ssl?
9537 SSL/TLS support: yes, no, required. <doc/wiki/SSL.txt>.
9538 Defaults to @samp{"required"}.
9541 @deftypevr {@code{dovecot-configuration} parameter} string ssl-cert
9542 PEM encoded X.509 SSL/TLS certificate (public key).
9543 Defaults to @samp{"</etc/dovecot/default.pem"}.
9546 @deftypevr {@code{dovecot-configuration} parameter} string ssl-key
9547 PEM encoded SSL/TLS private key. The key is opened before
9548 dropping root privileges, so keep the key file unreadable by anyone but
9550 Defaults to @samp{"</etc/dovecot/private/default.pem"}.
9553 @deftypevr {@code{dovecot-configuration} parameter} string ssl-key-password
9554 If key file is password protected, give the password here.
9555 Alternatively give it when starting dovecot with -p parameter. Since
9556 this file is often world-readable, you may want to place this setting
9557 instead to a different.
9558 Defaults to @samp{""}.
9561 @deftypevr {@code{dovecot-configuration} parameter} string ssl-ca
9562 PEM encoded trusted certificate authority. Set this only if you
9563 intend to use @samp{ssl-verify-client-cert? #t}. The file should
9564 contain the CA certificate(s) followed by the matching
9565 CRL(s). (e.g. @samp{ssl-ca </etc/ssl/certs/ca.pem}).
9566 Defaults to @samp{""}.
9569 @deftypevr {@code{dovecot-configuration} parameter} boolean ssl-require-crl?
9570 Require that CRL check succeeds for client certificates.
9571 Defaults to @samp{#t}.
9574 @deftypevr {@code{dovecot-configuration} parameter} boolean ssl-verify-client-cert?
9575 Request client to send a certificate. If you also want to require
9576 it, set @samp{auth-ssl-require-client-cert? #t} in auth section.
9577 Defaults to @samp{#f}.
9580 @deftypevr {@code{dovecot-configuration} parameter} string ssl-cert-username-field
9581 Which field from certificate to use for username. commonName and
9582 x500UniqueIdentifier are the usual choices. You'll also need to set
9583 @samp{auth-ssl-username-from-cert? #t}.
9584 Defaults to @samp{"commonName"}.
9587 @deftypevr {@code{dovecot-configuration} parameter} hours ssl-parameters-regenerate
9588 How often to regenerate the SSL parameters file. Generation is
9589 quite CPU intensive operation. The value is in hours, 0 disables
9590 regeneration entirely.
9591 Defaults to @samp{168}.
9594 @deftypevr {@code{dovecot-configuration} parameter} string ssl-protocols
9595 SSL protocols to use.
9596 Defaults to @samp{"!SSLv2"}.
9599 @deftypevr {@code{dovecot-configuration} parameter} string ssl-cipher-list
9601 Defaults to @samp{"ALL:!LOW:!SSLv2:!EXP:!aNULL"}.
9604 @deftypevr {@code{dovecot-configuration} parameter} string ssl-crypto-device
9605 SSL crypto device to use, for valid values run "openssl engine".
9606 Defaults to @samp{""}.
9609 @deftypevr {@code{dovecot-configuration} parameter} string postmaster-address
9610 Address to use when sending rejection mails.
9611 Default is postmaster@@<your domain>. %d expands to recipient domain.
9612 Defaults to @samp{""}.
9615 @deftypevr {@code{dovecot-configuration} parameter} string hostname
9616 Hostname to use in various parts of sent mails (e.g. in Message-Id)
9617 and in LMTP replies. Default is the system's real hostname@@domain.
9618 Defaults to @samp{""}.
9621 @deftypevr {@code{dovecot-configuration} parameter} boolean quota-full-tempfail?
9622 If user is over quota, return with temporary failure instead of
9624 Defaults to @samp{#f}.
9627 @deftypevr {@code{dovecot-configuration} parameter} file-name sendmail-path
9628 Binary to use for sending mails.
9629 Defaults to @samp{"/usr/sbin/sendmail"}.
9632 @deftypevr {@code{dovecot-configuration} parameter} string submission-host
9633 If non-empty, send mails via this SMTP host[:port] instead of
9635 Defaults to @samp{""}.
9638 @deftypevr {@code{dovecot-configuration} parameter} string rejection-subject
9639 Subject: header to use for rejection mails. You can use the same
9640 variables as for @samp{rejection-reason} below.
9641 Defaults to @samp{"Rejected: %s"}.
9644 @deftypevr {@code{dovecot-configuration} parameter} string rejection-reason
9645 Human readable error message for rejection mails. You can use
9658 Defaults to @samp{"Your message to <%t> was automatically rejected:%n%r"}.
9661 @deftypevr {@code{dovecot-configuration} parameter} string recipient-delimiter
9662 Delimiter character between local-part and detail in email
9664 Defaults to @samp{"+"}.
9667 @deftypevr {@code{dovecot-configuration} parameter} string lda-original-recipient-header
9668 Header where the original recipient address (SMTP's RCPT TO:
9669 address) is taken from if not available elsewhere. With dovecot-lda -a
9670 parameter overrides this. A commonly used header for this is
9672 Defaults to @samp{""}.
9675 @deftypevr {@code{dovecot-configuration} parameter} boolean lda-mailbox-autocreate?
9676 Should saving a mail to a nonexistent mailbox automatically create
9678 Defaults to @samp{#f}.
9681 @deftypevr {@code{dovecot-configuration} parameter} boolean lda-mailbox-autosubscribe?
9682 Should automatically created mailboxes be also automatically
9684 Defaults to @samp{#f}.
9687 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer imap-max-line-length
9688 Maximum IMAP command line length. Some clients generate very long
9689 command lines with huge mailboxes, so you may need to raise this if you
9690 get "Too long argument" or "IMAP command line too large" errors
9692 Defaults to @samp{64000}.
9695 @deftypevr {@code{dovecot-configuration} parameter} string imap-logout-format
9696 IMAP logout format string:
9699 total number of bytes read from client
9701 total number of bytes sent to client.
9703 Defaults to @samp{"in=%i out=%o"}.
9706 @deftypevr {@code{dovecot-configuration} parameter} string imap-capability
9707 Override the IMAP CAPABILITY response. If the value begins with '+',
9708 add the given capabilities on top of the defaults (e.g. +XFOO XBAR).
9709 Defaults to @samp{""}.
9712 @deftypevr {@code{dovecot-configuration} parameter} string imap-idle-notify-interval
9713 How long to wait between "OK Still here" notifications when client
9715 Defaults to @samp{"2 mins"}.
9718 @deftypevr {@code{dovecot-configuration} parameter} string imap-id-send
9719 ID field names and values to send to clients. Using * as the value
9720 makes Dovecot use the default value. The following fields have default
9721 values currently: name, version, os, os-version, support-url,
9723 Defaults to @samp{""}.
9726 @deftypevr {@code{dovecot-configuration} parameter} string imap-id-log
9727 ID fields sent by client to log. * means everything.
9728 Defaults to @samp{""}.
9731 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list imap-client-workarounds
9732 Workarounds for various client bugs:
9736 Send EXISTS/RECENT new mail notifications only when replying to NOOP and
9737 CHECK commands. Some clients ignore them otherwise, for example OSX
9738 Mail (<v2.1). Outlook Express breaks more badly though, without this it
9739 may show user "Message no longer in server" errors. Note that OE6
9740 still breaks even with this workaround if synchronization is set to
9743 @item tb-extra-mailbox-sep
9744 Thunderbird gets somehow confused with LAYOUT=fs (mbox and dbox) and
9745 adds extra @samp{/} suffixes to mailbox names. This option causes Dovecot to
9746 ignore the extra @samp{/} instead of treating it as invalid mailbox name.
9749 Show \Noselect flags for LSUB replies with LAYOUT=fs (e.g. mbox).
9750 This makes Thunderbird realize they aren't selectable and show them
9751 greyed out, instead of only later giving "not selectable" popup error.
9753 Defaults to @samp{()}.
9756 @deftypevr {@code{dovecot-configuration} parameter} string imap-urlauth-host
9757 Host allowed in URLAUTH URLs sent by client. "*" allows all.
9758 Defaults to @samp{""}.
9762 Whew! Lots of configuration options. The nice thing about it though is
9763 that GuixSD has a complete interface to Dovecot's configuration
9764 language. This allows not only a nice way to declare configurations,
9765 but also offers reflective capabilities as well: users can write code to
9766 inspect and transform configurations from within Scheme.
9768 However, it could be that you just want to get a @code{dovecot.conf} up
9769 and running. In that case, you can pass an
9770 @code{opaque-dovecot-configuration} as the @code{#:config} paramter to
9771 @code{dovecot-service}. As its name indicates, an opaque configuration
9772 does not have easy reflective capabilities.
9774 Available @code{opaque-dovecot-configuration} fields are:
9776 @deftypevr {@code{opaque-dovecot-configuration} parameter} package dovecot
9777 The dovecot package.
9780 @deftypevr {@code{opaque-dovecot-configuration} parameter} string string
9781 The contents of the @code{dovecot.conf}, as a string.
9784 For example, if your @code{dovecot.conf} is just the empty string, you
9785 could instantiate a dovecot service like this:
9788 (dovecot-service #:config
9789 (opaque-dovecot-configuration
9794 @subsubsection Web Services
9796 The @code{(gnu services web)} module provides the following service:
9798 @deffn {Scheme Procedure} nginx-service [#:nginx nginx] @
9799 [#:log-directory ``/var/log/nginx''] @
9800 [#:run-directory ``/var/run/nginx''] @
9803 Return a service that runs @var{nginx}, the nginx web server.
9805 The nginx daemon loads its runtime configuration from @var{config-file}.
9806 Log files are written to @var{log-directory} and temporary runtime data
9807 files are written to @var{run-directory}. For proper operation, these
9808 arguments should match what is in @var{config-file} to ensure that the
9809 directories are created when the service is activated.
9813 @node Various Services
9814 @subsubsection Various Services
9816 The @code{(gnu services lirc)} module provides the following service.
9818 @deffn {Scheme Procedure} lirc-service [#:lirc lirc] @
9819 [#:device #f] [#:driver #f] [#:config-file #f] @
9820 [#:extra-options '()]
9821 Return a service that runs @url{http://www.lirc.org,LIRC}, a daemon that
9822 decodes infrared signals from remote controls.
9824 Optionally, @var{device}, @var{driver} and @var{config-file}
9825 (configuration file name) may be specified. See @command{lircd} manual
9828 Finally, @var{extra-options} is a list of additional command-line options
9829 passed to @command{lircd}.
9832 @subsubsection Dictionary Services
9833 The @code{(gnu services dict)} module provides the following service:
9835 @deffn {Scheme Procedure} dicod-service [#:config (dicod-configuration)]
9836 Return a service that runs the @command{dicod} daemon, an implementation
9837 of DICT server (@pxref{Dicod,,, dico, GNU Dico Manual}).
9839 The optional @var{config} argument specifies the configuration for
9840 @command{dicod}, which should be a @code{<dicod-configuration>} object, by
9841 default it serves the GNU Collaborative International Dictonary of English.
9843 You can add @command{open localhost} to your @file{~/.dico} file to make
9844 @code{localhost} the default server for @command{dico} client
9845 (@pxref{Initialization File,,, dico, GNU Dico Manual}).
9848 @deftp {Data Type} dicod-configuration
9849 Data type representing the configuration of dicod.
9852 @item @code{dico} (default: @var{dico})
9853 Package object of the GNU Dico dictionary server.
9855 @item @code{interfaces} (default: @var{'("localhost")})
9856 This is the list of IP addresses and ports and possibly socket file
9857 names to listen to (@pxref{Server Settings, @code{listen} directive,,
9858 dico, GNU Dico Manual}).
9860 @item @code{databases} (default: @var{(list %dicod-database:gcide)})
9861 List of @code{<dicod-database>} objects denoting dictionaries to be served.
9865 @deftp {Data Type} dicod-database
9866 Data type representing a dictionary database.
9870 Name of the database, will be used in DICT commands.
9873 Name of the dicod module used by this database
9874 (@pxref{Modules,,, dico, GNU Dico Manual}).
9876 @item @code{options}
9877 List of strings or gexps representing the arguments for the module handler
9878 (@pxref{Handlers,,, dico, GNU Dico Manual}).
9882 @defvr {Scheme Variable} %dicod-database:gcide
9883 A @code{<dicod-database>} object serving the GNU Collaborative International
9884 Dictonary of English using the @code{gcide} package.
9887 @node Setuid Programs
9888 @subsection Setuid Programs
9890 @cindex setuid programs
9891 Some programs need to run with ``root'' privileges, even when they are
9892 launched by unprivileged users. A notorious example is the
9893 @command{passwd} program, which users can run to change their
9894 password, and which needs to access the @file{/etc/passwd} and
9895 @file{/etc/shadow} files---something normally restricted to root, for
9896 obvious security reasons. To address that, these executables are
9897 @dfn{setuid-root}, meaning that they always run with root privileges
9898 (@pxref{How Change Persona,,, libc, The GNU C Library Reference Manual},
9899 for more info about the setuid mechanism.)
9901 The store itself @emph{cannot} contain setuid programs: that would be a
9902 security issue since any user on the system can write derivations that
9903 populate the store (@pxref{The Store}). Thus, a different mechanism is
9904 used: instead of changing the setuid bit directly on files that are in
9905 the store, we let the system administrator @emph{declare} which programs
9906 should be setuid root.
9908 The @code{setuid-programs} field of an @code{operating-system}
9909 declaration contains a list of G-expressions denoting the names of
9910 programs to be setuid-root (@pxref{Using the Configuration System}).
9911 For instance, the @command{passwd} program, which is part of the Shadow
9912 package, can be designated by this G-expression (@pxref{G-Expressions}):
9915 #~(string-append #$shadow "/bin/passwd")
9918 A default set of setuid programs is defined by the
9919 @code{%setuid-programs} variable of the @code{(gnu system)} module.
9921 @defvr {Scheme Variable} %setuid-programs
9922 A list of G-expressions denoting common programs that are setuid-root.
9924 The list includes commands such as @command{passwd}, @command{ping},
9925 @command{su}, and @command{sudo}.
9928 Under the hood, the actual setuid programs are created in the
9929 @file{/run/setuid-programs} directory at system activation time. The
9930 files in this directory refer to the ``real'' binaries, which are in the
9933 @node X.509 Certificates
9934 @subsection X.509 Certificates
9936 @cindex HTTPS, certificates
9937 @cindex X.509 certificates
9939 Web servers available over HTTPS (that is, HTTP over the transport-layer
9940 security mechanism, TLS) send client programs an @dfn{X.509 certificate}
9941 that the client can then use to @emph{authenticate} the server. To do
9942 that, clients verify that the server's certificate is signed by a
9943 so-called @dfn{certificate authority} (CA). But to verify the CA's
9944 signature, clients must have first acquired the CA's certificate.
9946 Web browsers such as GNU@tie{}IceCat include their own set of CA
9947 certificates, such that they are able to verify CA signatures
9950 However, most other programs that can talk HTTPS---@command{wget},
9951 @command{git}, @command{w3m}, etc.---need to be told where CA
9952 certificates can be found.
9954 @cindex @code{nss-certs}
9955 In GuixSD, this is done by adding a package that provides certificates
9956 to the @code{packages} field of the @code{operating-system} declaration
9957 (@pxref{operating-system Reference}). GuixSD includes one such package,
9958 @code{nss-certs}, which is a set of CA certificates provided as part of
9959 Mozilla's Network Security Services.
9961 Note that it is @emph{not} part of @var{%base-packages}, so you need to
9962 explicitly add it. The @file{/etc/ssl/certs} directory, which is where
9963 most applications and libraries look for certificates by default, points
9964 to the certificates installed globally.
9966 Unprivileged users, including users of Guix on a foreign distro,
9967 can also install their own certificate package in
9968 their profile. A number of environment variables need to be defined so
9969 that applications and libraries know where to find them. Namely, the
9970 OpenSSL library honors the @code{SSL_CERT_DIR} and @code{SSL_CERT_FILE}
9971 variables. Some applications add their own environment variables; for
9972 instance, the Git version control system honors the certificate bundle
9973 pointed to by the @code{GIT_SSL_CAINFO} environment variable. Thus, you
9974 would typically run something like:
9977 $ guix package -i nss-certs
9978 $ export SSL_CERT_DIR="$HOME/.guix-profile/etc/ssl/certs"
9979 $ export SSL_CERT_FILE="$HOME/.guix-profile/etc/ssl/certs/ca-certificates.crt"
9980 $ export GIT_SSL_CAINFO="$SSL_CERT_FILE"
9983 @node Name Service Switch
9984 @subsection Name Service Switch
9986 @cindex name service switch
9988 The @code{(gnu system nss)} module provides bindings to the
9989 configuration file of the libc @dfn{name service switch} or @dfn{NSS}
9990 (@pxref{NSS Configuration File,,, libc, The GNU C Library Reference
9991 Manual}). In a nutshell, the NSS is a mechanism that allows libc to be
9992 extended with new ``name'' lookup methods for system databases, which
9993 includes host names, service names, user accounts, and more (@pxref{Name
9994 Service Switch, System Databases and Name Service Switch,, libc, The GNU
9995 C Library Reference Manual}).
9997 The NSS configuration specifies, for each system database, which lookup
9998 method is to be used, and how the various methods are chained
9999 together---for instance, under which circumstances NSS should try the
10000 next method in the list. The NSS configuration is given in the
10001 @code{name-service-switch} field of @code{operating-system} declarations
10002 (@pxref{operating-system Reference, @code{name-service-switch}}).
10005 @cindex .local, host name lookup
10006 As an example, the declaration below configures the NSS to use the
10007 @uref{http://0pointer.de/lennart/projects/nss-mdns/, @code{nss-mdns}
10008 back-end}, which supports host name lookups over multicast DNS (mDNS)
10009 for host names ending in @code{.local}:
10012 (name-service-switch
10013 (hosts (list %files ;first, check /etc/hosts
10015 ;; If the above did not succeed, try
10016 ;; with 'mdns_minimal'.
10018 (name "mdns_minimal")
10020 ;; 'mdns_minimal' is authoritative for
10021 ;; '.local'. When it returns "not found",
10022 ;; no need to try the next methods.
10023 (reaction (lookup-specification
10024 (not-found => return))))
10026 ;; Then fall back to DNS.
10030 ;; Finally, try with the "full" 'mdns'.
10035 Do not worry: the @code{%mdns-host-lookup-nss} variable (see below)
10036 contains this configuration, so you will not have to type it if all you
10037 want is to have @code{.local} host lookup working.
10039 Note that, in this case, in addition to setting the
10040 @code{name-service-switch} of the @code{operating-system} declaration,
10041 you also need to use @code{avahi-service} (@pxref{Networking Services,
10042 @code{avahi-service}}), or @var{%desktop-services}, which includes it
10043 (@pxref{Desktop Services}). Doing this makes @code{nss-mdns} accessible
10044 to the name service cache daemon (@pxref{Base Services,
10045 @code{nscd-service}}).
10047 For convenience, the following variables provide typical NSS
10050 @defvr {Scheme Variable} %default-nss
10051 This is the default name service switch configuration, a
10052 @code{name-service-switch} object.
10055 @defvr {Scheme Variable} %mdns-host-lookup-nss
10056 This is the name service switch configuration with support for host name
10057 lookup over multicast DNS (mDNS) for host names ending in @code{.local}.
10060 The reference for name service switch configuration is given below. It
10061 is a direct mapping of the configuration file format of the C library , so
10062 please refer to the C library manual for more information (@pxref{NSS
10063 Configuration File,,, libc, The GNU C Library Reference Manual}).
10064 Compared to the configuration file format of libc NSS, it has the advantage
10065 not only of adding this warm parenthetic feel that we like, but also
10066 static checks: you will know about syntax errors and typos as soon as you
10067 run @command{guix system}.
10069 @deftp {Data Type} name-service-switch
10071 This is the data type representation the configuration of libc's name
10072 service switch (NSS). Each field below represents one of the supported
10089 The system databases handled by the NSS. Each of these fields must be a
10090 list of @code{<name-service>} objects (see below).
10094 @deftp {Data Type} name-service
10096 This is the data type representing an actual name service and the
10097 associated lookup action.
10101 A string denoting the name service (@pxref{Services in the NSS
10102 configuration,,, libc, The GNU C Library Reference Manual}).
10104 Note that name services listed here must be visible to nscd. This is
10105 achieved by passing the @code{#:name-services} argument to
10106 @code{nscd-service} the list of packages providing the needed name
10107 services (@pxref{Base Services, @code{nscd-service}}).
10110 An action specified using the @code{lookup-specification} macro
10111 (@pxref{Actions in the NSS configuration,,, libc, The GNU C Library
10112 Reference Manual}). For example:
10115 (lookup-specification (unavailable => continue)
10116 (success => return))
10121 @node Initial RAM Disk
10122 @subsection Initial RAM Disk
10124 @cindex initial RAM disk (initrd)
10125 @cindex initrd (initial RAM disk)
10126 For bootstrapping purposes, the Linux-Libre kernel is passed an
10127 @dfn{initial RAM disk}, or @dfn{initrd}. An initrd contains a temporary
10128 root file system as well as an initialization script. The latter is
10129 responsible for mounting the real root file system, and for loading any
10130 kernel modules that may be needed to achieve that.
10132 The @code{initrd} field of an @code{operating-system} declaration allows
10133 you to specify which initrd you would like to use. The @code{(gnu
10134 system linux-initrd)} module provides two ways to build an initrd: the
10135 high-level @code{base-initrd} procedure, and the low-level
10136 @code{expression->initrd} procedure.
10138 The @code{base-initrd} procedure is intended to cover most common uses.
10139 For example, if you want to add a bunch of kernel modules to be loaded
10140 at boot time, you can define the @code{initrd} field of the operating
10141 system declaration like this:
10144 (initrd (lambda (file-systems . rest)
10145 ;; Create a standard initrd that has modules "foo.ko"
10146 ;; and "bar.ko", as well as their dependencies, in
10147 ;; addition to the modules available by default.
10148 (apply base-initrd file-systems
10149 #:extra-modules '("foo" "bar")
10153 The @code{base-initrd} procedure also handles common use cases that
10154 involves using the system as a QEMU guest, or as a ``live'' system with
10155 volatile root file system.
10157 The initial RAM disk produced by @code{base-initrd} honors several
10158 options passed on the Linux kernel command line (that is, arguments
10159 passed @i{via} the @code{linux} command of GRUB, or the
10160 @code{-append} option) of QEMU, notably:
10163 @item --load=@var{boot}
10164 Tell the initial RAM disk to load @var{boot}, a file containing a Scheme
10165 program, once it has mounted the root file system.
10167 GuixSD uses this option to yield control to a boot program that runs the
10168 service activation programs and then spawns the GNU@tie{}Shepherd, the
10169 initialization system.
10171 @item --root=@var{root}
10172 Mount @var{root} as the root file system. @var{root} can be a
10173 device name like @code{/dev/sda1}, a partition label, or a partition
10176 @item --system=@var{system}
10177 Have @file{/run/booted-system} and @file{/run/current-system} point to
10180 @item modprobe.blacklist=@var{modules}@dots{}
10181 @cindex module, black-listing
10182 @cindex black list, of kernel modules
10183 Instruct the initial RAM disk as well as the @command{modprobe} command
10184 (from the kmod package) to refuse to load @var{modules}. @var{modules}
10185 must be a comma-separated list of module names---e.g.,
10186 @code{usbkbd,9pnet}.
10189 Start a read-eval-print loop (REPL) from the initial RAM disk before it
10190 tries to load kernel modules and to mount the root file system. Our
10191 marketing team calls it @dfn{boot-to-Guile}. The Schemer in you will
10192 love it. @xref{Using Guile Interactively,,, guile, GNU Guile Reference
10193 Manual}, for more information on Guile's REPL.
10197 Now that you know all the features that initial RAM disks produced by
10198 @code{base-initrd} provide, here is how to use it and customize it
10201 @deffn {Monadic Procedure} base-initrd @var{file-systems} @
10202 [#:qemu-networking? #f] [#:virtio? #t] [#:volatile-root? #f] @
10203 [#:extra-modules '()] [#:mapped-devices '()]
10204 Return a monadic derivation that builds a generic initrd. @var{file-systems} is
10205 a list of file systems to be mounted by the initrd, possibly in addition to
10206 the root file system specified on the kernel command line via @code{--root}.
10207 @var{mapped-devices} is a list of device mappings to realize before
10208 @var{file-systems} are mounted (@pxref{Mapped Devices}).
10210 When @var{qemu-networking?} is true, set up networking with the standard QEMU
10211 parameters. When @var{virtio?} is true, load additional modules so that the
10212 initrd can be used as a QEMU guest with para-virtualized I/O drivers.
10214 When @var{volatile-root?} is true, the root file system is writable but any changes
10217 The initrd is automatically populated with all the kernel modules necessary
10218 for @var{file-systems} and for the given options. However, additional kernel
10219 modules can be listed in @var{extra-modules}. They will be added to the initrd, and
10220 loaded at boot time in the order in which they appear.
10223 Needless to say, the initrds we produce and use embed a
10224 statically-linked Guile, and the initialization program is a Guile
10225 program. That gives a lot of flexibility. The
10226 @code{expression->initrd} procedure builds such an initrd, given the
10227 program to run in that initrd.
10229 @deffn {Monadic Procedure} expression->initrd @var{exp} @
10230 [#:guile %guile-static-stripped] [#:name "guile-initrd"]
10231 Return a derivation that builds a Linux initrd (a gzipped cpio archive)
10232 containing @var{guile} and that evaluates @var{exp}, a G-expression,
10233 upon booting. All the derivations referenced by @var{exp} are
10234 automatically copied to the initrd.
10237 @node GRUB Configuration
10238 @subsection GRUB Configuration
10241 @cindex boot loader
10243 The operating system uses GNU@tie{}GRUB as its boot loader
10244 (@pxref{Overview, overview of GRUB,, grub, GNU GRUB Manual}). It is
10245 configured using a @code{grub-configuration} declaration. This data type
10246 is exported by the @code{(gnu system grub)} module and described below.
10248 @deftp {Data Type} grub-configuration
10249 The type of a GRUB configuration declaration.
10253 @item @code{device}
10254 This is a string denoting the boot device. It must be a device name
10255 understood by the @command{grub-install} command, such as
10256 @code{/dev/sda} or @code{(hd0)} (@pxref{Invoking grub-install,,, grub,
10259 @item @code{menu-entries} (default: @code{()})
10260 A possibly empty list of @code{menu-entry} objects (see below), denoting
10261 entries to appear in the GRUB boot menu, in addition to the current
10262 system entry and the entry pointing to previous system generations.
10264 @item @code{default-entry} (default: @code{0})
10265 The index of the default boot menu entry. Index 0 is for the entry of the
10268 @item @code{timeout} (default: @code{5})
10269 The number of seconds to wait for keyboard input before booting. Set to
10270 0 to boot immediately, and to -1 to wait indefinitely.
10272 @item @code{theme} (default: @var{%default-theme})
10273 The @code{grub-theme} object describing the theme to use.
10278 Should you want to list additional boot menu entries @i{via} the
10279 @code{menu-entries} field above, you will need to create them with the
10280 @code{menu-entry} form:
10282 @deftp {Data Type} menu-entry
10283 The type of an entry in the GRUB boot menu.
10288 The label to show in the menu---e.g., @code{"GNU"}.
10291 The Linux kernel to boot.
10293 @item @code{linux-arguments} (default: @code{()})
10294 The list of extra Linux kernel command-line arguments---e.g.,
10295 @code{("console=ttyS0")}.
10297 @item @code{initrd}
10298 A G-Expression or string denoting the file name of the initial RAM disk
10299 to use (@pxref{G-Expressions}).
10304 @c FIXME: Write documentation once it's stable.
10305 Themes are created using the @code{grub-theme} form, which is not
10308 @defvr {Scheme Variable} %default-theme
10309 This is the default GRUB theme used by the operating system, with a
10310 fancy background image displaying the GNU and Guix logos.
10314 @node Invoking guix system
10315 @subsection Invoking @code{guix system}
10317 Once you have written an operating system declaration as seen in the
10318 previous section, it can be @dfn{instantiated} using the @command{guix
10319 system} command. The synopsis is:
10322 guix system @var{options}@dots{} @var{action} @var{file}
10325 @var{file} must be the name of a file containing an
10326 @code{operating-system} declaration. @var{action} specifies how the
10327 operating system is instantiated. Currently the following values are
10332 Build the operating system described in @var{file}, activate it, and
10333 switch to it@footnote{This action is usable only on systems already
10336 This effects all the configuration specified in @var{file}: user
10337 accounts, system services, global package list, setuid programs, etc.
10338 The command starts system services specified in @var{file} that are not
10339 currently running; if a service is currently running, it does not
10340 attempt to upgrade it since this would not be possible without stopping it
10343 It also adds a GRUB menu entry for the new OS configuration, and moves
10344 entries for older configurations to a submenu---unless
10345 @option{--no-grub} is passed.
10348 @c The paragraph below refers to the problem discussed at
10349 @c <http://lists.gnu.org/archive/html/guix-devel/2014-08/msg00057.html>.
10350 It is highly recommended to run @command{guix pull} once before you run
10351 @command{guix system reconfigure} for the first time (@pxref{Invoking
10352 guix pull}). Failing to do that you would see an older version of Guix
10353 once @command{reconfigure} has completed.
10357 Build the derivation of the operating system, which includes all the
10358 configuration files and programs needed to boot and run the system.
10359 This action does not actually install anything.
10362 Populate the given directory with all the files necessary to run the
10363 operating system specified in @var{file}. This is useful for first-time
10364 installations of GuixSD. For instance:
10367 guix system init my-os-config.scm /mnt
10370 copies to @file{/mnt} all the store items required by the configuration
10371 specified in @file{my-os-config.scm}. This includes configuration
10372 files, packages, and so on. It also creates other essential files
10373 needed for the system to operate correctly---e.g., the @file{/etc},
10374 @file{/var}, and @file{/run} directories, and the @file{/bin/sh} file.
10376 This command also installs GRUB on the device specified in
10377 @file{my-os-config}, unless the @option{--no-grub} option was passed.
10380 @cindex virtual machine
10382 @anchor{guix system vm}
10383 Build a virtual machine that contains the operating system declared in
10384 @var{file}, and return a script to run that virtual machine (VM).
10385 Arguments given to the script are passed to QEMU.
10387 The VM shares its store with the host system.
10389 Additional file systems can be shared between the host and the VM using
10390 the @code{--share} and @code{--expose} command-line options: the former
10391 specifies a directory to be shared with write access, while the latter
10392 provides read-only access to the shared directory.
10394 The example below creates a VM in which the user's home directory is
10395 accessible read-only, and where the @file{/exchange} directory is a
10396 read-write mapping of @file{$HOME/tmp} on the host:
10399 guix system vm my-config.scm \
10400 --expose=$HOME --share=$HOME/tmp=/exchange
10403 On GNU/Linux, the default is to boot directly to the kernel; this has
10404 the advantage of requiring only a very tiny root disk image since the
10405 store of the host can then be mounted.
10407 The @code{--full-boot} option forces a complete boot sequence, starting
10408 with the bootloader. This requires more disk space since a root image
10409 containing at least the kernel, initrd, and bootloader data files must
10410 be created. The @code{--image-size} option can be used to specify the
10415 Return a virtual machine or disk image of the operating system declared
10416 in @var{file} that stands alone. Use the @option{--image-size} option
10417 to specify the size of the image.
10419 When using @code{vm-image}, the returned image is in qcow2 format, which
10420 the QEMU emulator can efficiently use. @xref{Running GuixSD in a VM},
10421 for more information on how to run the image in a virtual machine.
10423 When using @code{disk-image}, a raw disk image is produced; it can be
10424 copied as is to a USB stick, for instance. Assuming @code{/dev/sdc} is
10425 the device corresponding to a USB stick, one can copy the image to it
10426 using the following command:
10429 # dd if=$(guix system disk-image my-os.scm) of=/dev/sdc
10433 Return a script to run the operating system declared in @var{file}
10434 within a container. Containers are a set of lightweight isolation
10435 mechanisms provided by the kernel Linux-libre. Containers are
10436 substantially less resource-demanding than full virtual machines since
10437 the kernel, shared objects, and other resources can be shared with the
10438 host system; this also means they provide thinner isolation.
10440 Currently, the script must be run as root in order to support more than
10441 a single user and group. The container shares its store with the host
10444 As with the @code{vm} action (@pxref{guix system vm}), additional file
10445 systems to be shared between the host and container can be specified
10446 using the @option{--share} and @option{--expose} options:
10449 guix system container my-config.scm \
10450 --expose=$HOME --share=$HOME/tmp=/exchange
10454 This option requires Linux-libre 3.19 or newer.
10459 @var{options} can contain any of the common build options (@pxref{Common
10460 Build Options}). In addition, @var{options} can contain one of the
10464 @item --system=@var{system}
10465 @itemx -s @var{system}
10466 Attempt to build for @var{system} instead of the host system type.
10467 This works as per @command{guix build} (@pxref{Invoking guix build}).
10471 Return the derivation file name of the given operating system without
10474 @item --image-size=@var{size}
10475 For the @code{vm-image} and @code{disk-image} actions, create an image
10476 of the given @var{size}. @var{size} may be a number of bytes, or it may
10477 include a unit as a suffix (@pxref{Block size, size specifications,,
10478 coreutils, GNU Coreutils}).
10480 @item --on-error=@var{strategy}
10481 Apply @var{strategy} when an error occurs when reading @var{file}.
10482 @var{strategy} may be one of the following:
10485 @item nothing-special
10486 Report the error concisely and exit. This is the default strategy.
10489 Likewise, but also display a backtrace.
10492 Report the error and enter Guile's debugger. From there, you can run
10493 commands such as @code{,bt} to get a backtrace, @code{,locals} to
10494 display local variable values, and more generally inspect the state of the
10495 program. @xref{Debug Commands,,, guile, GNU Guile Reference Manual}, for
10496 a list of available debugging commands.
10501 All the actions above, except @code{build} and @code{init},
10502 can use KVM support in the Linux-libre kernel. Specifically, if the
10503 machine has hardware virtualization support, the corresponding
10504 KVM kernel module should be loaded, and the @file{/dev/kvm} device node
10505 must exist and be readable and writable by the user and by the
10506 build users of the daemon (@pxref{Build Environment Setup}).
10509 Once you have built, configured, re-configured, and re-re-configured
10510 your GuixSD installation, you may find it useful to list the operating
10511 system generations available on disk---and that you can choose from the
10516 @item list-generations
10517 List a summary of each generation of the operating system available on
10518 disk, in a human-readable way. This is similar to the
10519 @option{--list-generations} option of @command{guix package}
10520 (@pxref{Invoking guix package}).
10522 Optionally, one can specify a pattern, with the same syntax that is used
10523 in @command{guix package --list-generations}, to restrict the list of
10524 generations displayed. For instance, the following command displays
10525 generations that are up to 10 days old:
10528 $ guix system list-generations 10d
10533 The @command{guix system} command has even more to offer! The following
10534 sub-commands allow you to visualize how your system services relate to
10537 @anchor{system-extension-graph}
10540 @item extension-graph
10541 Emit in Dot/Graphviz format to standard output the @dfn{service
10542 extension graph} of the operating system defined in @var{file}
10543 (@pxref{Service Composition}, for more information on service
10549 $ guix system extension-graph @var{file} | dot -Tpdf > services.pdf
10552 produces a PDF file showing the extension relations among services.
10554 @anchor{system-shepherd-graph}
10555 @item shepherd-graph
10556 Emit in Dot/Graphviz format to standard output the @dfn{dependency
10557 graph} of shepherd services of the operating system defined in
10558 @var{file}. @xref{Shepherd Services}, for more information and for an
10563 @node Running GuixSD in a VM
10564 @subsection Running GuixSD in a Virtual Machine
10566 One way to run GuixSD in a virtual machine (VM) is to build a GuixSD
10567 virtual machine image using @command{guix system vm-image}
10568 (@pxref{Invoking guix system}). The returned image is in qcow2 format,
10569 which the @uref{http://qemu.org/, QEMU emulator} can efficiently use.
10571 To run the image in QEMU, copy it out of the store (@pxref{The Store})
10572 and give yourself permission to write to the copy. When invoking QEMU,
10573 you must choose a system emulator that is suitable for your hardware
10574 platform. Here is a minimal QEMU invocation that will boot the result
10575 of @command{guix system vm-image} on x86_64 hardware:
10578 $ qemu-system-x86_64 \
10579 -net user -net nic,model=virtio \
10580 -enable-kvm -m 256 /tmp/qemu-image
10583 Here is what each of these options means:
10586 @item qemu-system-x86_64
10587 This specifies the hardware platform to emulate. This should match the
10591 Enable the unprivileged user-mode network stack. The guest OS can
10592 access the host but not vice versa. This is the simplest way to get the
10593 guest OS online. If you do not choose a network stack, the boot will
10596 @item -net nic,model=virtio
10597 You must create a network interface of a given model. If you do not
10598 create a NIC, the boot will fail. Assuming your hardware platform is
10599 x86_64, you can get a list of available NIC models by running
10600 @command{qemu-system-x86_64 -net nic,model=help}.
10603 If your system has hardware virtualization extensions, enabling the
10604 virtual machine support (KVM) of the Linux kernel will make things run
10608 RAM available to the guest OS, in mebibytes. Defaults to 128@tie{}MiB,
10609 which may be insufficent for some operations.
10611 @item /tmp/qemu-image
10612 The file name of the qcow2 image.
10615 @node Defining Services
10616 @subsection Defining Services
10618 The previous sections show the available services and how one can combine
10619 them in an @code{operating-system} declaration. But how do we define
10620 them in the first place? And what is a service anyway?
10623 * Service Composition:: The model for composing services.
10624 * Service Types and Services:: Types and services.
10625 * Service Reference:: API reference.
10626 * Shepherd Services:: A particular type of service.
10629 @node Service Composition
10630 @subsubsection Service Composition
10634 Here we define a @dfn{service} as, broadly, something that extends the
10635 functionality of the operating system. Often a service is a process---a
10636 @dfn{daemon}---started when the system boots: a secure shell server, a
10637 Web server, the Guix build daemon, etc. Sometimes a service is a daemon
10638 whose execution can be triggered by another daemon---e.g., an FTP server
10639 started by @command{inetd} or a D-Bus service activated by
10640 @command{dbus-daemon}. Occasionally, a service does not map to a
10641 daemon. For instance, the ``account'' service collects user accounts
10642 and makes sure they exist when the system runs; the ``udev'' service
10643 collects device management rules and makes them available to the eudev
10644 daemon; the @file{/etc} service populates the @file{/etc} directory
10647 @cindex service extensions
10648 GuixSD services are connected by @dfn{extensions}. For instance, the
10649 secure shell service @emph{extends} the Shepherd---the GuixSD
10650 initialization system, running as PID@tie{}1---by giving it the command
10651 lines to start and stop the secure shell daemon (@pxref{Networking
10652 Services, @code{lsh-service}}); the UPower service extends the D-Bus
10653 service by passing it its @file{.service} specification, and extends the
10654 udev service by passing it device management rules (@pxref{Desktop
10655 Services, @code{upower-service}}); the Guix daemon service extends the
10656 Shepherd by passing it the command lines to start and stop the daemon,
10657 and extends the account service by passing it a list of required build
10658 user accounts (@pxref{Base Services}).
10660 All in all, services and their ``extends'' relations form a directed
10661 acyclic graph (DAG). If we represent services as boxes and extensions
10662 as arrows, a typical system might provide something like this:
10664 @image{images/service-graph,,5in,Typical service extension graph.}
10666 @cindex system service
10667 At the bottom, we see the @dfn{system service}, which produces the
10668 directory containing everything to run and boot the system, as returned
10669 by the @command{guix system build} command. @xref{Service Reference},
10670 to learn about the other service types shown here.
10671 @xref{system-extension-graph, the @command{guix system extension-graph}
10672 command}, for information on how to generate this representation for a
10673 particular operating system definition.
10675 @cindex service types
10676 Technically, developers can define @dfn{service types} to express these
10677 relations. There can be any number of services of a given type on the
10678 system---for instance, a system running two instances of the GNU secure
10679 shell server (lsh) has two instances of @var{lsh-service-type}, with
10680 different parameters.
10682 The following section describes the programming interface for service
10683 types and services.
10685 @node Service Types and Services
10686 @subsubsection Service Types and Services
10688 A @dfn{service type} is a node in the DAG described above. Let us start
10689 with a simple example, the service type for the Guix build daemon
10690 (@pxref{Invoking guix-daemon}):
10693 (define guix-service-type
10697 (list (service-extension shepherd-root-service-type guix-shepherd-service)
10698 (service-extension account-service-type guix-accounts)
10699 (service-extension activation-service-type guix-activation)))))
10703 It defines two things:
10707 A name, whose sole purpose is to make inspection and debugging easier.
10710 A list of @dfn{service extensions}, where each extension designates the
10711 target service type and a procedure that, given the parameters of the
10712 service, returns a list of objects to extend the service of that type.
10714 Every service type has at least one service extension. The only
10715 exception is the @dfn{boot service type}, which is the ultimate service.
10718 In this example, @var{guix-service-type} extends three services:
10721 @item shepherd-root-service-type
10722 The @var{guix-shepherd-service} procedure defines how the Shepherd
10723 service is extended. Namely, it returns a @code{<shepherd-service>}
10724 object that defines how @command{guix-daemon} is started and stopped
10725 (@pxref{Shepherd Services}).
10727 @item account-service-type
10728 This extension for this service is computed by @var{guix-accounts},
10729 which returns a list of @code{user-group} and @code{user-account}
10730 objects representing the build user accounts (@pxref{Invoking
10733 @item activation-service-type
10734 Here @var{guix-activation} is a procedure that returns a gexp, which is
10735 a code snippet to run at ``activation time''---e.g., when the service is
10739 A service of this type is instantiated like this:
10742 (service guix-service-type
10743 (guix-configuration
10745 (use-substitutes? #f)))
10748 The second argument to the @code{service} form is a value representing
10749 the parameters of this specific service instance.
10750 @xref{guix-configuration-type, @code{guix-configuration}}, for
10751 information about the @code{guix-configuration} data type.
10753 @var{guix-service-type} is quite simple because it extends other
10754 services but is not extensible itself.
10756 @c @subsubsubsection Extensible Service Types
10758 The service type for an @emph{extensible} service looks like this:
10761 (define udev-service-type
10762 (service-type (name 'udev)
10764 (list (service-extension shepherd-root-service-type
10765 udev-shepherd-service)))
10767 (compose concatenate) ;concatenate the list of rules
10768 (extend (lambda (config rules)
10770 (($ <udev-configuration> udev initial-rules)
10771 (udev-configuration
10772 (udev udev) ;the udev package to use
10773 (rules (append initial-rules rules)))))))))
10776 This is the service type for the
10777 @uref{https://wiki.gentoo.org/wiki/Project:Eudev, eudev device
10778 management daemon}. Compared to the previous example, in addition to an
10779 extension of @var{shepherd-root-service-type}, we see two new fields:
10783 This is the procedure to @dfn{compose} the list of extensions to
10784 services of this type.
10786 Services can extend the udev service by passing it lists of rules; we
10787 compose those extensions simply by concatenating them.
10790 This procedure defines how the value of the service is @dfn{extended} with
10791 the composition of the extensions.
10793 Udev extensions are composed into a list of rules, but the udev service
10794 value is itself a @code{<udev-configuration>} record. So here, we
10795 extend that record by appending the list of rules it contains to the
10796 list of contributed rules.
10799 There can be only one instance of an extensible service type such as
10800 @var{udev-service-type}. If there were more, the
10801 @code{service-extension} specifications would be ambiguous.
10803 Still here? The next section provides a reference of the programming
10804 interface for services.
10806 @node Service Reference
10807 @subsubsection Service Reference
10809 We have seen an overview of service types (@pxref{Service Types and
10810 Services}). This section provides a reference on how to manipulate
10811 services and service types. This interface is provided by the
10812 @code{(gnu services)} module.
10814 @deffn {Scheme Procedure} service @var{type} @var{value}
10815 Return a new service of @var{type}, a @code{<service-type>} object (see
10816 below.) @var{value} can be any object; it represents the parameters of
10817 this particular service instance.
10820 @deffn {Scheme Procedure} service? @var{obj}
10821 Return true if @var{obj} is a service.
10824 @deffn {Scheme Procedure} service-kind @var{service}
10825 Return the type of @var{service}---i.e., a @code{<service-type>} object.
10828 @deffn {Scheme Procedure} service-parameters @var{service}
10829 Return the value associated with @var{service}. It represents its
10833 Here is an example of how a service is created and manipulated:
10837 (service nginx-service-type
10838 (nginx-configuration
10840 (log-directory log-directory)
10841 (run-directory run-directory)
10842 (file config-file))))
10847 (eq? (service-kind s) nginx-service-type)
10851 The @code{modify-services} form provides a handy way to change the
10852 parameters of some of the services of a list such as
10853 @var{%base-services} (@pxref{Base Services, @code{%base-services}}). It
10854 evalutes to a list of services. Of course, you could always use
10855 standard list combinators such as @code{map} and @code{fold} to do that
10856 (@pxref{SRFI-1, List Library,, guile, GNU Guile Reference Manual});
10857 @code{modify-services} simply provides a more concise form for this
10860 @deffn {Scheme Syntax} modify-services @var{services} @
10861 (@var{type} @var{variable} => @var{body}) @dots{}
10863 Modify the services listed in @var{services} according to the given
10864 clauses. Each clause has the form:
10867 (@var{type} @var{variable} => @var{body})
10870 where @var{type} is a service type---e.g.,
10871 @code{guix-service-type}---and @var{variable} is an identifier that is
10872 bound within the @var{body} to the service parameters---e.g., a
10873 @code{guix-configuration} instance---of the original service of that
10876 The @var{body} should evaluate to the new service parameters, which will
10877 be used to configure the new service. This new service will replace the
10878 original in the resulting list. Because a service's service parameters
10879 are created using @code{define-record-type*}, you can write a succint
10880 @var{body} that evaluates to the new service parameters by using the
10881 @code{inherit} feature that @code{define-record-type*} provides.
10883 @xref{Using the Configuration System}, for example usage.
10887 Next comes the programming interface for service types. This is
10888 something you want to know when writing new service definitions, but not
10889 necessarily when simply looking for ways to customize your
10890 @code{operating-system} declaration.
10892 @deftp {Data Type} service-type
10893 @cindex service type
10894 This is the representation of a @dfn{service type} (@pxref{Service Types
10899 This is a symbol, used only to simplify inspection and debugging.
10901 @item @code{extensions}
10902 A non-empty list of @code{<service-extension>} objects (see below).
10904 @item @code{compose} (default: @code{#f})
10905 If this is @code{#f}, then the service type denotes services that cannot
10906 be extended---i.e., services that do not receive ``values'' from other
10909 Otherwise, it must be a one-argument procedure. The procedure is called
10910 by @code{fold-services} and is passed a list of values collected from
10911 extensions. It must return a value that is a valid parameter value for
10912 the service instance.
10914 @item @code{extend} (default: @code{#f})
10915 If this is @code{#f}, services of this type cannot be extended.
10917 Otherwise, it must be a two-argument procedure: @code{fold-services}
10918 calls it, passing it the initial value of the service as the first argument
10919 and the result of applying @code{compose} to the extension values as the
10923 @xref{Service Types and Services}, for examples.
10926 @deffn {Scheme Procedure} service-extension @var{target-type} @
10928 Return a new extension for services of type @var{target-type}.
10929 @var{compute} must be a one-argument procedure: @code{fold-services}
10930 calls it, passing it the value associated with the service that provides
10931 the extension; it must return a valid value for the target service.
10934 @deffn {Scheme Procedure} service-extension? @var{obj}
10935 Return true if @var{obj} is a service extension.
10938 At the core of the service abstraction lies the @code{fold-services}
10939 procedure, which is responsible for ``compiling'' a list of services
10940 down to a single directory that contains everything needed to boot and
10941 run the system---the directory shown by the @command{guix system build}
10942 command (@pxref{Invoking guix system}). In essence, it propagates
10943 service extensions down the service graph, updating each node parameters
10944 on the way, until it reaches the root node.
10946 @deffn {Scheme Procedure} fold-services @var{services} @
10947 [#:target-type @var{system-service-type}]
10948 Fold @var{services} by propagating their extensions down to the root of
10949 type @var{target-type}; return the root service adjusted accordingly.
10952 Lastly, the @code{(gnu services)} module also defines several essential
10953 service types, some of which are listed below.
10955 @defvr {Scheme Variable} system-service-type
10956 This is the root of the service graph. It produces the system directory
10957 as returned by the @command{guix system build} command.
10960 @defvr {Scheme Variable} boot-service-type
10961 The type of the ``boot service'', which produces the @dfn{boot script}.
10962 The boot script is what the initial RAM disk runs when booting.
10965 @defvr {Scheme Variable} etc-service-type
10966 The type of the @file{/etc} service. This service can be extended by
10967 passing it name/file tuples such as:
10970 (list `("issue" ,(plain-file "issue" "Welcome!\n")))
10973 In this example, the effect would be to add an @file{/etc/issue} file
10974 pointing to the given file.
10977 @defvr {Scheme Variable} setuid-program-service-type
10978 Type for the ``setuid-program service''. This service collects lists of
10979 executable file names, passed as gexps, and adds them to the set of
10980 setuid-root programs on the system (@pxref{Setuid Programs}).
10983 @defvr {Scheme Variable} profile-service-type
10984 Type of the service that populates the @dfn{system profile}---i.e., the
10985 programs under @file{/run/current-system/profile}. Other services can
10986 extend it by passing it lists of packages to add to the system profile.
10990 @node Shepherd Services
10991 @subsubsection Shepherd Services
10994 @cindex init system
10995 The @code{(gnu services shepherd)} module provides a way to define
10996 services managed by the GNU@tie{}Shepherd, which is the GuixSD
10997 initialization system---the first process that is started when the
10998 system boots, also known as PID@tie{}1
10999 (@pxref{Introduction,,, shepherd, The GNU Shepherd Manual}).
11001 Services in the Shepherd can depend on each other. For instance, the
11002 SSH daemon may need to be started after the syslog daemon has been
11003 started, which in turn can only happen once all the file systems have
11004 been mounted. The simple operating system defined earlier (@pxref{Using
11005 the Configuration System}) results in a service graph like this:
11007 @image{images/shepherd-graph,,5in,Typical shepherd service graph.}
11009 You can actually generate such a graph for any operating system
11010 definition using the @command{guix system shepherd-graph} command
11011 (@pxref{system-shepherd-graph, @command{guix system shepherd-graph}}).
11013 The @var{%shepherd-root-service} is a service object representing
11014 PID@tie{}1, of type @var{shepherd-root-service-type}; it can be extended
11015 by passing it lists of @code{<shepherd-service>} objects.
11017 @deftp {Data Type} shepherd-service
11018 The data type representing a service managed by the Shepherd.
11021 @item @code{provision}
11022 This is a list of symbols denoting what the service provides.
11024 These are the names that may be passed to @command{herd start},
11025 @command{herd status}, and similar commands (@pxref{Invoking herd,,,
11026 shepherd, The GNU Shepherd Manual}). @xref{Slots of services, the
11027 @code{provides} slot,, shepherd, The GNU Shepherd Manual}, for details.
11029 @item @code{requirements} (default: @code{'()})
11030 List of symbols denoting the Shepherd services this one depends on.
11032 @item @code{respawn?} (default: @code{#t})
11033 Whether to restart the service when it stops, for instance when the
11034 underlying process dies.
11037 @itemx @code{stop} (default: @code{#~(const #f)})
11038 The @code{start} and @code{stop} fields refer to the Shepherd's
11039 facilities to start and stop processes (@pxref{Service De- and
11040 Constructors,,, shepherd, The GNU Shepherd Manual}). They are given as
11041 G-expressions that get expanded in the Shepherd configuration file
11042 (@pxref{G-Expressions}).
11044 @item @code{documentation}
11045 A documentation string, as shown when running:
11048 herd doc @var{service-name}
11051 where @var{service-name} is one of the symbols in @var{provision}
11052 (@pxref{Invoking herd,,, shepherd, The GNU Shepherd Manual}).
11054 @item @code{modules} (default: @var{%default-modules})
11055 This is the list of modules that must be in scope when @code{start} and
11056 @code{stop} are evaluated.
11061 @defvr {Scheme Variable} shepherd-root-service-type
11062 The service type for the Shepherd ``root service''---i.e., PID@tie{}1.
11064 This is the service type that extensions target when they want to create
11065 shepherd services (@pxref{Service Types and Services}, for an example).
11066 Each extension must pass a list of @code{<shepherd-service>}.
11069 @defvr {Scheme Variable} %shepherd-root-service
11070 This service represents PID@tie{}1.
11074 @node Installing Debugging Files
11075 @section Installing Debugging Files
11077 @cindex debugging files
11078 Program binaries, as produced by the GCC compilers for instance, are
11079 typically written in the ELF format, with a section containing
11080 @dfn{debugging information}. Debugging information is what allows the
11081 debugger, GDB, to map binary code to source code; it is required to
11082 debug a compiled program in good conditions.
11084 The problem with debugging information is that is takes up a fair amount
11085 of disk space. For example, debugging information for the GNU C Library
11086 weighs in at more than 60 MiB. Thus, as a user, keeping all the
11087 debugging info of all the installed programs is usually not an option.
11088 Yet, space savings should not come at the cost of an impediment to
11089 debugging---especially in the GNU system, which should make it easier
11090 for users to exert their computing freedom (@pxref{GNU Distribution}).
11092 Thankfully, the GNU Binary Utilities (Binutils) and GDB provide a
11093 mechanism that allows users to get the best of both worlds: debugging
11094 information can be stripped from the binaries and stored in separate
11095 files. GDB is then able to load debugging information from those files,
11096 when they are available (@pxref{Separate Debug Files,,, gdb, Debugging
11099 The GNU distribution takes advantage of this by storing debugging
11100 information in the @code{lib/debug} sub-directory of a separate package
11101 output unimaginatively called @code{debug} (@pxref{Packages with
11102 Multiple Outputs}). Users can choose to install the @code{debug} output
11103 of a package when they need it. For instance, the following command
11104 installs the debugging information for the GNU C Library and for GNU
11108 guix package -i glibc:debug guile:debug
11111 GDB must then be told to look for debug files in the user's profile, by
11112 setting the @code{debug-file-directory} variable (consider setting it
11113 from the @file{~/.gdbinit} file, @pxref{Startup,,, gdb, Debugging with
11117 (gdb) set debug-file-directory ~/.guix-profile/lib/debug
11120 From there on, GDB will pick up debugging information from the
11121 @code{.debug} files under @file{~/.guix-profile/lib/debug}.
11123 In addition, you will most likely want GDB to be able to show the source
11124 code being debugged. To do that, you will have to unpack the source
11125 code of the package of interest (obtained with @code{guix build
11126 --source}, @pxref{Invoking guix build}), and to point GDB to that source
11127 directory using the @code{directory} command (@pxref{Source Path,
11128 @code{directory},, gdb, Debugging with GDB}).
11130 @c XXX: keep me up-to-date
11131 The @code{debug} output mechanism in Guix is implemented by the
11132 @code{gnu-build-system} (@pxref{Build Systems}). Currently, it is
11133 opt-in---debugging information is available only for the packages
11134 with definitions explicitly declaring a @code{debug} output. This may be
11135 changed to opt-out in the future if our build farm servers can handle
11136 the load. To check whether a package has a @code{debug} output, use
11137 @command{guix package --list-available} (@pxref{Invoking guix package}).
11140 @node Security Updates
11141 @section Security Updates
11143 @cindex security updates
11144 @cindex security vulnerabilities
11145 Occasionally, important security vulnerabilities are discovered in software
11146 packages and must be patched. Guix developers try hard to keep track of
11147 known vulnerabilities and to apply fixes as soon as possible in the
11148 @code{master} branch of Guix (we do not yet provide a ``stable'' branch
11149 containing only security updates.) The @command{guix lint} tool helps
11150 developers find out about vulnerable versions of software packages in the
11155 gnu/packages/base.scm:652:2: glibc-2.21: probably vulnerable to CVE-2015-1781, CVE-2015-7547
11156 gnu/packages/gcc.scm:334:2: gcc-4.9.3: probably vulnerable to CVE-2015-5276
11157 gnu/packages/image.scm:312:2: openjpeg-2.1.0: probably vulnerable to CVE-2016-1923, CVE-2016-1924
11161 @xref{Invoking guix lint}, for more information.
11164 As of version @value{VERSION}, the feature described below is considered
11168 Guix follows a functional
11169 package management discipline (@pxref{Introduction}), which implies
11170 that, when a package is changed, @emph{every package that depends on it}
11171 must be rebuilt. This can significantly slow down the deployment of
11172 fixes in core packages such as libc or Bash, since basically the whole
11173 distribution would need to be rebuilt. Using pre-built binaries helps
11174 (@pxref{Substitutes}), but deployment may still take more time than
11178 To address this, Guix implements @dfn{grafts}, a mechanism that allows
11179 for fast deployment of critical updates without the costs associated
11180 with a whole-distribution rebuild. The idea is to rebuild only the
11181 package that needs to be patched, and then to ``graft'' it onto packages
11182 explicitly installed by the user and that were previously referring to
11183 the original package. The cost of grafting is typically very low, and
11184 order of magnitudes lower than a full rebuild of the dependency chain.
11186 @cindex replacements of packages, for grafts
11187 For instance, suppose a security update needs to be applied to Bash.
11188 Guix developers will provide a package definition for the ``fixed''
11189 Bash, say @var{bash-fixed}, in the usual way (@pxref{Defining
11190 Packages}). Then, the original package definition is augmented with a
11191 @code{replacement} field pointing to the package containing the bug fix:
11198 (replacement bash-fixed)))
11201 From there on, any package depending directly or indirectly on Bash---as
11202 reported by @command{guix gc --requisites} (@pxref{Invoking guix
11203 gc})---that is installed is automatically ``rewritten'' to refer to
11204 @var{bash-fixed} instead of @var{bash}. This grafting process takes
11205 time proportional to the size of the package, usually less than a
11206 minute for an ``average'' package on a recent machine. Grafting is
11207 recursive: when an indirect dependency requires grafting, then grafting
11208 ``propagates'' up to the package that the user is installing.
11210 Currently, the graft and the package it replaces (@var{bash-fixed} and
11211 @var{bash} in the example above) must have the exact same @code{name}
11212 and @code{version} fields. This restriction mostly comes from the fact
11213 that grafting works by patching files, including binary files, directly.
11214 Other restrictions may apply: for instance, when adding a graft to a
11215 package providing a shared library, the original shared library and its
11216 replacement must have the same @code{SONAME} and be binary-compatible.
11218 The @option{--no-grafts} command-line option allows you to forcefully
11219 avoid grafting (@pxref{Common Build Options, @option{--no-grafts}}).
11223 guix build bash --no-grafts
11227 returns the store file name of the original Bash, whereas:
11234 returns the store file name of the ``fixed'', replacement Bash. This
11235 allows you to distinguish between the two variants of Bash.
11237 To verify which Bash your whole profile refers to, you can run
11238 (@pxref{Invoking guix gc}):
11241 guix gc -R `readlink -f ~/.guix-profile` | grep bash
11245 @dots{} and compare the store file names that you get with those above.
11246 Likewise for a complete GuixSD system generation:
11249 guix gc -R `guix system build my-config.scm` | grep bash
11252 Lastly, to check which Bash running processes are using, you can use the
11253 @command{lsof} command:
11256 lsof | grep /gnu/store/.*bash
11260 @node Package Modules
11261 @section Package Modules
11263 From a programming viewpoint, the package definitions of the
11264 GNU distribution are provided by Guile modules in the @code{(gnu packages
11265 @dots{})} name space@footnote{Note that packages under the @code{(gnu
11266 packages @dots{})} module name space are not necessarily ``GNU
11267 packages''. This module naming scheme follows the usual Guile module
11268 naming convention: @code{gnu} means that these modules are distributed
11269 as part of the GNU system, and @code{packages} identifies modules that
11270 define packages.} (@pxref{Modules, Guile modules,, guile, GNU Guile
11271 Reference Manual}). For instance, the @code{(gnu packages emacs)}
11272 module exports a variable named @code{emacs}, which is bound to a
11273 @code{<package>} object (@pxref{Defining Packages}).
11275 The @code{(gnu packages @dots{})} module name space is
11276 automatically scanned for packages by the command-line tools. For
11277 instance, when running @code{guix package -i emacs}, all the @code{(gnu
11278 packages @dots{})} modules are scanned until one that exports a package
11279 object whose name is @code{emacs} is found. This package search
11280 facility is implemented in the @code{(gnu packages)} module.
11282 @cindex customization, of packages
11283 @cindex package module search path
11284 Users can store package definitions in modules with different
11285 names---e.g., @code{(my-packages emacs)}@footnote{Note that the file
11286 name and module name must match. For instance, the @code{(my-packages
11287 emacs)} module must be stored in a @file{my-packages/emacs.scm} file
11288 relative to the load path specified with @option{--load-path} or
11289 @code{GUIX_PACKAGE_PATH}. @xref{Modules and the File System,,,
11290 guile, GNU Guile Reference Manual}, for details.}. These package definitions
11291 will not be visible by default. Users can invoke commands such as
11292 @command{guix package} and @command{guix build} with the
11293 @code{-e} option so that they know where to find the package. Better
11294 yet, they can use the
11295 @code{-L} option of these commands to make those modules visible
11296 (@pxref{Invoking guix build, @code{--load-path}}), or define the
11297 @code{GUIX_PACKAGE_PATH} environment variable. This environment
11298 variable makes it easy to extend or customize the distribution and is
11299 honored by all the user interfaces.
11301 @defvr {Environment Variable} GUIX_PACKAGE_PATH
11302 This is a colon-separated list of directories to search for additional
11303 package modules. Directories listed in this variable take precedence
11304 over the own modules of the distribution.
11307 The distribution is fully @dfn{bootstrapped} and @dfn{self-contained}:
11308 each package is built based solely on other packages in the
11309 distribution. The root of this dependency graph is a small set of
11310 @dfn{bootstrap binaries}, provided by the @code{(gnu packages
11311 bootstrap)} module. For more information on bootstrapping,
11312 @pxref{Bootstrapping}.
11314 @node Packaging Guidelines
11315 @section Packaging Guidelines
11317 The GNU distribution is nascent and may well lack some of your favorite
11318 packages. This section describes how you can help make the distribution
11319 grow. @xref{Contributing}, for additional information on how you can
11322 Free software packages are usually distributed in the form of
11323 @dfn{source code tarballs}---typically @file{tar.gz} files that contain
11324 all the source files. Adding a package to the distribution means
11325 essentially two things: adding a @dfn{recipe} that describes how to
11326 build the package, including a list of other packages required to build
11327 it, and adding @dfn{package metadata} along with that recipe, such as a
11328 description and licensing information.
11330 In Guix all this information is embodied in @dfn{package definitions}.
11331 Package definitions provide a high-level view of the package. They are
11332 written using the syntax of the Scheme programming language; in fact,
11333 for each package we define a variable bound to the package definition,
11334 and export that variable from a module (@pxref{Package Modules}).
11335 However, in-depth Scheme knowledge is @emph{not} a prerequisite for
11336 creating packages. For more information on package definitions,
11337 @pxref{Defining Packages}.
11339 Once a package definition is in place, stored in a file in the Guix
11340 source tree, it can be tested using the @command{guix build} command
11341 (@pxref{Invoking guix build}). For example, assuming the new package is
11342 called @code{gnew}, you may run this command from the Guix build tree
11343 (@pxref{Running Guix Before It Is Installed}):
11346 ./pre-inst-env guix build gnew --keep-failed
11349 Using @code{--keep-failed} makes it easier to debug build failures since
11350 it provides access to the failed build tree. Another useful
11351 command-line option when debugging is @code{--log-file}, to access the
11354 If the package is unknown to the @command{guix} command, it may be that
11355 the source file contains a syntax error, or lacks a @code{define-public}
11356 clause to export the package variable. To figure it out, you may load
11357 the module from Guile to get more information about the actual error:
11360 ./pre-inst-env guile -c '(use-modules (gnu packages gnew))'
11363 Once your package builds correctly, please send us a patch
11364 (@pxref{Contributing}). Well, if you need help, we will be happy to
11365 help you too. Once the patch is committed in the Guix repository, the
11366 new package automatically gets built on the supported platforms by
11367 @url{http://hydra.gnu.org/jobset/gnu/master, our continuous integration
11370 @cindex substituter
11371 Users can obtain the new package definition simply by running
11372 @command{guix pull} (@pxref{Invoking guix pull}). When
11373 @code{hydra.gnu.org} is done building the package, installing the
11374 package automatically downloads binaries from there
11375 (@pxref{Substitutes}). The only place where human intervention is
11376 needed is to review and apply the patch.
11380 * Software Freedom:: What may go into the distribution.
11381 * Package Naming:: What's in a name?
11382 * Version Numbers:: When the name is not enough.
11383 * Synopses and Descriptions:: Helping users find the right package.
11384 * Python Modules:: Taming the snake.
11385 * Perl Modules:: Little pearls.
11386 * Java Packages:: Coffee break.
11387 * Fonts:: Fond of fonts.
11390 @node Software Freedom
11391 @subsection Software Freedom
11393 @c Adapted from http://www.gnu.org/philosophy/philosophy.html.
11395 The GNU operating system has been developed so that users can have
11396 freedom in their computing. GNU is @dfn{free software}, meaning that
11397 users have the @url{http://www.gnu.org/philosophy/free-sw.html,four
11398 essential freedoms}: to run the program, to study and change the program
11399 in source code form, to redistribute exact copies, and to distribute
11400 modified versions. Packages found in the GNU distribution provide only
11401 software that conveys these four freedoms.
11403 In addition, the GNU distribution follow the
11404 @url{http://www.gnu.org/distros/free-system-distribution-guidelines.html,free
11405 software distribution guidelines}. Among other things, these guidelines
11406 reject non-free firmware, recommendations of non-free software, and
11407 discuss ways to deal with trademarks and patents.
11409 Some otherwise free upstream package sources contain a small and optional
11410 subset that violates the above guidelines, for instance because this subset
11411 is itself non-free code. When that happens, the offending items are removed
11412 with appropriate patches or code snippets in the @code{origin} form of the
11413 package (@pxref{Defining Packages}). This way, @code{guix
11414 build --source} returns the ``freed'' source rather than the unmodified
11418 @node Package Naming
11419 @subsection Package Naming
11421 A package has actually two names associated with it:
11422 First, there is the name of the @emph{Scheme variable}, the one following
11423 @code{define-public}. By this name, the package can be made known in the
11424 Scheme code, for instance as input to another package. Second, there is
11425 the string in the @code{name} field of a package definition. This name
11426 is used by package management commands such as
11427 @command{guix package} and @command{guix build}.
11429 Both are usually the same and correspond to the lowercase conversion of
11430 the project name chosen upstream, with underscores replaced with
11431 hyphens. For instance, GNUnet is available as @code{gnunet}, and
11432 SDL_net as @code{sdl-net}.
11434 We do not add @code{lib} prefixes for library packages, unless these are
11435 already part of the official project name. But @pxref{Python
11436 Modules} and @ref{Perl Modules} for special rules concerning modules for
11437 the Python and Perl languages.
11439 Font package names are handled differently, @pxref{Fonts}.
11442 @node Version Numbers
11443 @subsection Version Numbers
11445 We usually package only the latest version of a given free software
11446 project. But sometimes, for instance for incompatible library versions,
11447 two (or more) versions of the same package are needed. These require
11448 different Scheme variable names. We use the name as defined
11449 in @ref{Package Naming}
11450 for the most recent version; previous versions use the same name, suffixed
11451 by @code{-} and the smallest prefix of the version number that may
11452 distinguish the two versions.
11454 The name inside the package definition is the same for all versions of a
11455 package and does not contain any version number.
11457 For instance, the versions 2.24.20 and 3.9.12 of GTK+ may be packaged as follows:
11460 (define-public gtk+
11465 (define-public gtk+-2
11468 (version "2.24.20")
11471 If we also wanted GTK+ 3.8.2, this would be packaged as
11473 (define-public gtk+-3.8
11480 @c See <https://lists.gnu.org/archive/html/guix-devel/2016-01/msg00425.html>,
11481 @c for a discussion of what follows.
11482 @cindex version number, for VCS snapshots
11483 Occasionally, we package snapshots of upstream's version control system
11484 (VCS) instead of formal releases. This should remain exceptional,
11485 because it is up to upstream developers to clarify what the stable
11486 release is. Yet, it is sometimes necessary. So, what should we put in
11487 the @code{version} field?
11489 Clearly, we need to make the commit identifier of the VCS snapshot
11490 visible in the version string, but we also need to make sure that the
11491 version string is monotonically increasing so that @command{guix package
11492 --upgrade} can determine which version is newer. Since commit
11493 identifiers, notably with Git, are not monotonically increasing, we add
11494 a revision number that we increase each time we upgrade to a newer
11495 snapshot. The resulting version string looks like this:
11500 | | `-- upstream commit ID
11502 | `--- Guix package revision
11504 latest upstream version
11507 It is a good idea to strip commit identifiers in the @code{version}
11508 field to, say, 7 digits. It avoids an aesthetic annoyance (assuming
11509 aesthetics have a role to play here) as well as problems related to OS
11510 limits such as the maximum shebang length (127 bytes for the Linux
11511 kernel.) It is best to use the full commit identifiers in
11512 @code{origin}s, though, to avoid ambiguities. A typical package
11513 definition may look like this:
11517 (let ((commit "c3f29bc928d5900971f65965feaae59e1272a3f7")
11518 (revision "1")) ;Guix package revision
11520 (version (string-append "0.9-" revision "."
11521 (string-take commit 7)))
11524 (uri (git-reference
11525 (url "git://example.org/my-package.git")
11527 (sha256 (base32 "1mbikn@dots{}"))
11528 (file-name (string-append "my-package-" version
11534 @node Synopses and Descriptions
11535 @subsection Synopses and Descriptions
11537 As we have seen before, each package in GNU@tie{}Guix includes a
11538 synopsis and a description (@pxref{Defining Packages}). Synopses and
11539 descriptions are important: They are what @command{guix package
11540 --search} searches, and a crucial piece of information to help users
11541 determine whether a given package suits their needs. Consequently,
11542 packagers should pay attention to what goes into them.
11544 Synopses must start with a capital letter and must not end with a
11545 period. They must not start with ``a'' or ``the'', which usually does
11546 not bring anything; for instance, prefer ``File-frobbing tool'' over ``A
11547 tool that frobs files''. The synopsis should say what the package
11548 is---e.g., ``Core GNU utilities (file, text, shell)''---or what it is
11549 used for---e.g., the synopsis for GNU@tie{}grep is ``Print lines
11550 matching a pattern''.
11552 Keep in mind that the synopsis must be meaningful for a very wide
11553 audience. For example, ``Manipulate alignments in the SAM format''
11554 might make sense for a seasoned bioinformatics researcher, but might be
11555 fairly unhelpful or even misleading to a non-specialized audience. It
11556 is a good idea to come up with a synopsis that gives an idea of the
11557 application domain of the package. In this example, this might give
11558 something like ``Manipulate nucleotide sequence alignments'', which
11559 hopefully gives the user a better idea of whether this is what they are
11562 Descriptions should take between five and ten lines. Use full
11563 sentences, and avoid using acronyms without first introducing them.
11564 Please avoid marketing phrases such as ``world-leading'',
11565 ``industrial-strength'', and ``next-generation'', and avoid superlatives
11566 like ``the most advanced''---they are not helpful to users looking for a
11567 package and may even sound suspicious. Instead, try to be factual,
11568 mentioning use cases and features.
11570 @cindex Texinfo markup, in package descriptions
11571 Descriptions can include Texinfo markup, which is useful to introduce
11572 ornaments such as @code{@@code} or @code{@@dfn}, bullet lists, or
11573 hyperlinks (@pxref{Overview,,, texinfo, GNU Texinfo}). However you
11574 should be careful when using some characters for example @samp{@@} and
11575 curly braces which are the basic special characters in Texinfo
11576 (@pxref{Special Characters,,, texinfo, GNU Texinfo}). User interfaces
11577 such as @command{guix package --show} take care of rendering it
11580 Synopses and descriptions are translated by volunteers
11581 @uref{http://translationproject.org/domain/guix-packages.html, at the
11582 Translation Project} so that as many users as possible can read them in
11583 their native language. User interfaces search them and display them in
11584 the language specified by the current locale.
11586 Translation is a lot of work so, as a packager, please pay even more
11587 attention to your synopses and descriptions as every change may entail
11588 additional work for translators. In order to help them, it is possible
11589 to make recommendations or instructions visible to them by inserting
11590 special comments like this (@pxref{xgettext Invocation,,, gettext, GNU
11594 ;; TRANSLATORS: "X11 resize-and-rotate" should not be translated.
11595 (description "ARandR is designed to provide a simple visual front end
11596 for the X11 resize-and-rotate (RandR) extension. @dots{}")
11600 @node Python Modules
11601 @subsection Python Modules
11603 We currently package Python 2 and Python 3, under the Scheme variable names
11604 @code{python-2} and @code{python} as explained in @ref{Version Numbers}.
11605 To avoid confusion and naming clashes with other programming languages, it
11606 seems desirable that the name of a package for a Python module contains
11607 the word @code{python}.
11609 Some modules are compatible with only one version of Python, others with both.
11610 If the package Foo compiles only with Python 3, we name it
11611 @code{python-foo}; if it compiles only with Python 2, we name it
11612 @code{python2-foo}. If it is compatible with both versions, we create two
11613 packages with the corresponding names.
11615 If a project already contains the word @code{python}, we drop this;
11616 for instance, the module python-dateutil is packaged under the names
11617 @code{python-dateutil} and @code{python2-dateutil}. If the project name
11618 starts with @code{py} (e.g. @code{pytz}), we keep it and prefix it as
11623 @subsection Perl Modules
11625 Perl programs standing for themselves are named as any other package,
11626 using the lowercase upstream name.
11627 For Perl packages containing a single class, we use the lowercase class name,
11628 replace all occurrences of @code{::} by dashes and prepend the prefix
11630 So the class @code{XML::Parser} becomes @code{perl-xml-parser}.
11631 Modules containing several classes keep their lowercase upstream name and
11632 are also prepended by @code{perl-}. Such modules tend to have the word
11633 @code{perl} somewhere in their name, which gets dropped in favor of the
11634 prefix. For instance, @code{libwww-perl} becomes @code{perl-libwww}.
11637 @node Java Packages
11638 @subsection Java Packages
11640 Java programs standing for themselves are named as any other package,
11641 using the lowercase upstream name.
11643 To avoid confusion and naming clashes with other programming languages,
11644 it is desirable that the name of a package for a Java package is
11645 prefixed with @code{java-}. If a project already contains the word
11646 @code{java}, we drop this; for instance, the package @code{ngsjava} is
11647 packaged under the name @code{java-ngs}.
11649 For Java packages containing a single class or a small class hierarchy,
11650 we use the lowercase class name, replace all occurrences of @code{.} by
11651 dashes and prepend the prefix @code{java-}. So the class
11652 @code{apache.commons.cli} becomes package
11653 @code{java-apache-commons-cli}.
11659 For fonts that are in general not installed by a user for typesetting
11660 purposes, or that are distributed as part of a larger software package,
11661 we rely on the general packaging rules for software; for instance, this
11662 applies to the fonts delivered as part of the X.Org system or fonts that
11663 are part of TeX Live.
11665 To make it easier for a user to search for fonts, names for other packages
11666 containing only fonts are constructed as follows, independently of the
11667 upstream package name.
11669 The name of a package containing only one font family starts with
11670 @code{font-}; it is followed by the foundry name and a dash @code{-}
11671 if the foundry is known, and the font family name, in which spaces are
11672 replaced by dashes (and as usual, all upper case letters are transformed
11674 For example, the Gentium font family by SIL is packaged under the name
11675 @code{font-sil-gentium}.
11677 For a package containing several font families, the name of the collection
11678 is used in the place of the font family name.
11679 For instance, the Liberation fonts consist of three families,
11680 Liberation Sans, Liberation Serif and Liberation Mono.
11681 These could be packaged separately under the names
11682 @code{font-liberation-sans} and so on; but as they are distributed together
11683 under a common name, we prefer to package them together as
11684 @code{font-liberation}.
11686 In the case where several formats of the same font family or font collection
11687 are packaged separately, a short form of the format, prepended by a dash,
11688 is added to the package name. We use @code{-ttf} for TrueType fonts,
11689 @code{-otf} for OpenType fonts and @code{-type1} for PostScript Type 1
11694 @node Bootstrapping
11695 @section Bootstrapping
11697 @c Adapted from the ELS 2013 paper.
11699 @cindex bootstrapping
11701 Bootstrapping in our context refers to how the distribution gets built
11702 ``from nothing''. Remember that the build environment of a derivation
11703 contains nothing but its declared inputs (@pxref{Introduction}). So
11704 there's an obvious chicken-and-egg problem: how does the first package
11705 get built? How does the first compiler get compiled? Note that this is
11706 a question of interest only to the curious hacker, not to the regular
11707 user, so you can shamelessly skip this section if you consider yourself
11708 a ``regular user''.
11710 @cindex bootstrap binaries
11711 The GNU system is primarily made of C code, with libc at its core. The
11712 GNU build system itself assumes the availability of a Bourne shell and
11713 command-line tools provided by GNU Coreutils, Awk, Findutils, `sed', and
11714 `grep'. Furthermore, build programs---programs that run
11715 @code{./configure}, @code{make}, etc.---are written in Guile Scheme
11716 (@pxref{Derivations}). Consequently, to be able to build anything at
11717 all, from scratch, Guix relies on pre-built binaries of Guile, GCC,
11718 Binutils, libc, and the other packages mentioned above---the
11719 @dfn{bootstrap binaries}.
11721 These bootstrap binaries are ``taken for granted'', though we can also
11722 re-create them if needed (more on that later).
11724 @unnumberedsubsec Preparing to Use the Bootstrap Binaries
11726 @c As of Emacs 24.3, Info-mode displays the image, but since it's a
11727 @c large image, it's hard to scroll. Oh well.
11728 @image{images/bootstrap-graph,6in,,Dependency graph of the early bootstrap derivations}
11730 The figure above shows the very beginning of the dependency graph of the
11731 distribution, corresponding to the package definitions of the @code{(gnu
11732 packages bootstrap)} module. A similar figure can be generated with
11733 @command{guix graph} (@pxref{Invoking guix graph}), along the lines of:
11736 guix graph -t derivation \
11737 -e '(@@@@ (gnu packages bootstrap) %bootstrap-gcc)' \
11741 At this level of detail, things are
11742 slightly complex. First, Guile itself consists of an ELF executable,
11743 along with many source and compiled Scheme files that are dynamically
11744 loaded when it runs. This gets stored in the @file{guile-2.0.7.tar.xz}
11745 tarball shown in this graph. This tarball is part of Guix's ``source''
11746 distribution, and gets inserted into the store with @code{add-to-store}
11747 (@pxref{The Store}).
11749 But how do we write a derivation that unpacks this tarball and adds it
11750 to the store? To solve this problem, the @code{guile-bootstrap-2.0.drv}
11751 derivation---the first one that gets built---uses @code{bash} as its
11752 builder, which runs @code{build-bootstrap-guile.sh}, which in turn calls
11753 @code{tar} to unpack the tarball. Thus, @file{bash}, @file{tar},
11754 @file{xz}, and @file{mkdir} are statically-linked binaries, also part of
11755 the Guix source distribution, whose sole purpose is to allow the Guile
11756 tarball to be unpacked.
11758 Once @code{guile-bootstrap-2.0.drv} is built, we have a functioning
11759 Guile that can be used to run subsequent build programs. Its first task
11760 is to download tarballs containing the other pre-built binaries---this
11761 is what the @code{.tar.xz.drv} derivations do. Guix modules such as
11762 @code{ftp-client.scm} are used for this purpose. The
11763 @code{module-import.drv} derivations import those modules in a directory
11764 in the store, using the original layout. The
11765 @code{module-import-compiled.drv} derivations compile those modules, and
11766 write them in an output directory with the right layout. This
11767 corresponds to the @code{#:modules} argument of
11768 @code{build-expression->derivation} (@pxref{Derivations}).
11770 Finally, the various tarballs are unpacked by the
11771 derivations @code{gcc-bootstrap-0.drv}, @code{glibc-bootstrap-0.drv},
11772 etc., at which point we have a working C tool chain.
11775 @unnumberedsubsec Building the Build Tools
11777 Bootstrapping is complete when we have a full tool chain that does not
11778 depend on the pre-built bootstrap tools discussed above. This
11779 no-dependency requirement is verified by checking whether the files of
11780 the final tool chain contain references to the @file{/gnu/store}
11781 directories of the bootstrap inputs. The process that leads to this
11782 ``final'' tool chain is described by the package definitions found in
11783 the @code{(gnu packages commencement)} module.
11785 The @command{guix graph} command allows us to ``zoom out'' compared to
11786 the graph above, by looking at the level of package objects instead of
11787 individual derivations---remember that a package may translate to
11788 several derivations, typically one derivation to download its source,
11789 one to build the Guile modules it needs, and one to actually build the
11790 package from source. The command:
11793 guix graph -t bag \
11794 -e '(@@@@ (gnu packages commencement)
11795 glibc-final-with-bootstrap-bash)' | dot -Tps > t.ps
11799 produces the dependency graph leading to the ``final'' C
11800 library@footnote{You may notice the @code{glibc-intermediate} label,
11801 suggesting that it is not @emph{quite} final, but as a good
11802 approximation, we will consider it final.}, depicted below.
11804 @image{images/bootstrap-packages,6in,,Dependency graph of the early packages}
11806 @c See <http://lists.gnu.org/archive/html/gnu-system-discuss/2012-10/msg00000.html>.
11807 The first tool that gets built with the bootstrap binaries is
11808 GNU@tie{}Make---noted @code{make-boot0} above---which is a prerequisite
11809 for all the following packages. From there Findutils and Diffutils get
11812 Then come the first-stage Binutils and GCC, built as pseudo cross
11813 tools---i.e., with @code{--target} equal to @code{--host}. They are
11814 used to build libc. Thanks to this cross-build trick, this libc is
11815 guaranteed not to hold any reference to the initial tool chain.
11817 From there the final Binutils and GCC (not shown above) are built.
11819 from the final Binutils, and links programs against the just-built libc.
11820 This tool chain is used to build the other packages used by Guix and by
11821 the GNU Build System: Guile, Bash, Coreutils, etc.
11823 And voilà! At this point we have the complete set of build tools that
11824 the GNU Build System expects. These are in the @code{%final-inputs}
11825 variable of the @code{(gnu packages commencement)} module, and are
11826 implicitly used by any package that uses @code{gnu-build-system}
11827 (@pxref{Build Systems, @code{gnu-build-system}}).
11830 @unnumberedsubsec Building the Bootstrap Binaries
11832 Because the final tool chain does not depend on the bootstrap binaries,
11833 those rarely need to be updated. Nevertheless, it is useful to have an
11834 automated way to produce them, should an update occur, and this is what
11835 the @code{(gnu packages make-bootstrap)} module provides.
11837 The following command builds the tarballs containing the bootstrap
11838 binaries (Guile, Binutils, GCC, libc, and a tarball containing a mixture
11839 of Coreutils and other basic command-line tools):
11842 guix build bootstrap-tarballs
11845 The generated tarballs are those that should be referred to in the
11846 @code{(gnu packages bootstrap)} module mentioned at the beginning of
11849 Still here? Then perhaps by now you've started to wonder: when do we
11850 reach a fixed point? That is an interesting question! The answer is
11851 unknown, but if you would like to investigate further (and have
11852 significant computational and storage resources to do so), then let us
11856 @section Porting to a New Platform
11858 As discussed above, the GNU distribution is self-contained, and
11859 self-containment is achieved by relying on pre-built ``bootstrap
11860 binaries'' (@pxref{Bootstrapping}). These binaries are specific to an
11861 operating system kernel, CPU architecture, and application binary
11862 interface (ABI). Thus, to port the distribution to a platform that is
11863 not yet supported, one must build those bootstrap binaries, and update
11864 the @code{(gnu packages bootstrap)} module to use them on that platform.
11866 Fortunately, Guix can @emph{cross compile} those bootstrap binaries.
11867 When everything goes well, and assuming the GNU tool chain supports the
11868 target platform, this can be as simple as running a command like this
11872 guix build --target=armv5tel-linux-gnueabi bootstrap-tarballs
11875 For this to work, the @code{glibc-dynamic-linker} procedure in
11876 @code{(gnu packages bootstrap)} must be augmented to return the right
11877 file name for libc's dynamic linker on that platform; likewise,
11878 @code{system->linux-architecture} in @code{(gnu packages linux)} must be
11879 taught about the new platform.
11881 Once these are built, the @code{(gnu packages bootstrap)} module needs
11882 to be updated to refer to these binaries on the target platform. That
11883 is, the hashes and URLs of the bootstrap tarballs for the new platform
11884 must be added alongside those of the currently supported platforms. The
11885 bootstrap Guile tarball is treated specially: it is expected to be
11886 available locally, and @file{gnu/local.mk} has rules do download it for
11887 the supported architectures; a rule for the new platform must be added
11890 In practice, there may be some complications. First, it may be that the
11891 extended GNU triplet that specifies an ABI (like the @code{eabi} suffix
11892 above) is not recognized by all the GNU tools. Typically, glibc
11893 recognizes some of these, whereas GCC uses an extra @code{--with-abi}
11894 configure flag (see @code{gcc.scm} for examples of how to handle this).
11895 Second, some of the required packages could fail to build for that
11896 platform. Lastly, the generated binaries could be broken for some
11899 @c *********************************************************************
11900 @include contributing.texi
11902 @c *********************************************************************
11903 @node Acknowledgments
11904 @chapter Acknowledgments
11906 Guix is based on the @uref{http://nixos.org/nix/, Nix package manager},
11907 which was designed and
11908 implemented by Eelco Dolstra, with contributions from other people (see
11909 the @file{nix/AUTHORS} file in Guix.) Nix pioneered functional package
11910 management, and promoted unprecedented features, such as transactional
11911 package upgrades and rollbacks, per-user profiles, and referentially
11912 transparent build processes. Without this work, Guix would not exist.
11914 The Nix-based software distributions, Nixpkgs and NixOS, have also been
11915 an inspiration for Guix.
11917 GNU@tie{}Guix itself is a collective work with contributions from a
11918 number of people. See the @file{AUTHORS} file in Guix for more
11919 information on these fine people. The @file{THANKS} file lists people
11920 who have helped by reporting bugs, taking care of the infrastructure,
11921 providing artwork and themes, making suggestions, and more---thank you!
11924 @c *********************************************************************
11925 @node GNU Free Documentation License
11926 @appendix GNU Free Documentation License
11928 @include fdl-1.3.texi
11930 @c *********************************************************************
11931 @node Concept Index
11932 @unnumbered Concept Index
11935 @node Programming Index
11936 @unnumbered Programming Index
11937 @syncodeindex tp fn
11938 @syncodeindex vr fn
11943 @c Local Variables:
11944 @c ispell-local-dictionary: "american";