6 @documentencoding UTF-8
7 @settitle GNU Guix Reference Manual
13 Copyright @copyright{} 2012, 2013, 2014, 2015 Ludovic Courtès@*
14 Copyright @copyright{} 2013, 2014 Andreas Enge@*
15 Copyright @copyright{} 2013 Nikita Karetnikov@*
16 Copyright @copyright{} 2015 Mathieu Lirzin@*
17 Copyright @copyright{} 2014 Pierre-Antoine Rault@*
18 Copyright @copyright{} 2015 Taylan Ulrich Bayırlı/Kammer
20 Permission is granted to copy, distribute and/or modify this document
21 under the terms of the GNU Free Documentation License, Version 1.3 or
22 any later version published by the Free Software Foundation; with no
23 Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A
24 copy of the license is included in the section entitled ``GNU Free
25 Documentation License''.
28 @dircategory Package management
30 * guix: (guix). Guix, the functional package manager.
31 * guix package: (guix)Invoking guix package
32 Managing packages with Guix.
33 * guix build: (guix)Invoking guix build
34 Building packages with Guix.
35 * guix system: (guix)Invoking guix system
36 Managing the operating system configuration.
39 @dircategory Software development
41 * guix environment: (guix)Invoking guix environment
42 Building development environments with Guix.
46 @title GNU Guix Reference Manual
47 @subtitle Using the GNU Guix Functional Package Manager
48 @author Ludovic Courtès
50 @author Nikita Karetnikov
53 @vskip 0pt plus 1filll
54 Edition @value{EDITION} @*
62 @c *********************************************************************
66 This document describes GNU Guix version @value{VERSION}, a functional
67 package management tool written for the GNU system.
70 * Introduction:: What is Guix about?
71 * Installation:: Installing Guix.
72 * Package Management:: Package installation, upgrade, etc.
73 * Emacs Interface:: Using Guix from Emacs.
74 * Programming Interface:: Using Guix in Scheme.
75 * Utilities:: Package management commands.
76 * GNU Distribution:: Software for your friendly GNU system.
77 * Contributing:: Your help needed!
79 * Acknowledgments:: Thanks!
80 * GNU Free Documentation License:: The license of this manual.
81 * Concept Index:: Concepts.
82 * Programming Index:: Data types, functions, and variables.
85 --- The Detailed Node Listing ---
89 * Binary Installation:: Getting Guix running in no time!
90 * Requirements:: Software needed to build and run Guix.
91 * Running the Test Suite:: Testing Guix.
92 * Setting Up the Daemon:: Preparing the build daemon's environment.
93 * Invoking guix-daemon:: Running the build daemon.
94 * Application Setup:: Application-specific setup.
98 * Build Environment Setup:: Preparing the isolated build environment.
99 * Daemon Offload Setup:: Offloading builds to remote machines.
103 * Features:: How Guix will make your life brighter.
104 * Invoking guix package:: Package installation, removal, etc.
105 * Substitutes:: Downloading pre-built binaries.
106 * Packages with Multiple Outputs:: Single source package, multiple outputs.
107 * Invoking guix gc:: Running the garbage collector.
108 * Invoking guix pull:: Fetching the latest Guix and distribution.
109 * Invoking guix archive:: Exporting and importing store files.
113 * Initial Setup: Emacs Initial Setup. Preparing @file{~/.emacs}.
114 * Package Management: Emacs Package Management. Managing packages and generations.
115 * Popup Interface: Emacs Popup Interface. Magit-like interface for guix commands.
116 * Prettify Mode: Emacs Prettify. Abbreviating @file{/gnu/store/@dots{}} file names.
117 * Completions: Emacs Completions. Completing @command{guix} shell command.
119 Programming Interface
121 * Defining Packages:: Defining new packages.
122 * Build Systems:: Specifying how packages are built.
123 * The Store:: Manipulating the package store.
124 * Derivations:: Low-level interface to package derivations.
125 * The Store Monad:: Purely functional interface to the store.
126 * G-Expressions:: Manipulating build expressions.
130 * package Reference:: The package data type.
131 * origin Reference:: The origin data type.
135 * Invoking guix build:: Building packages from the command line.
136 * Invoking guix edit:: Editing package definitions.
137 * Invoking guix download:: Downloading a file and printing its hash.
138 * Invoking guix hash:: Computing the cryptographic hash of a file.
139 * Invoking guix import:: Importing package definitions.
140 * Invoking guix refresh:: Updating package definitions.
141 * Invoking guix lint:: Finding errors in package definitions.
142 * Invoking guix size:: Profiling disk usage.
143 * Invoking guix graph:: Visualizing the graph of packages.
144 * Invoking guix environment:: Setting up development environments.
145 * Invoking guix publish:: Sharing substitutes.
149 * System Installation:: Installing the whole operating system.
150 * System Configuration:: Configuring the operating system.
151 * Installing Debugging Files:: Feeding the debugger.
152 * Security Updates:: Deploying security fixes quickly.
153 * Package Modules:: Packages from the programmer's viewpoint.
154 * Packaging Guidelines:: Growing the distribution.
155 * Bootstrapping:: GNU/Linux built from scratch.
156 * Porting:: Targeting another platform or kernel.
160 * Using the Configuration System:: Customizing your GNU system.
161 * operating-system Reference:: Detail of operating-system declarations.
162 * File Systems:: Configuring file system mounts.
163 * Mapped Devices:: Block device extra processing.
164 * User Accounts:: Specifying user accounts.
165 * Locales:: Language and cultural convention settings.
166 * Services:: Specifying system services.
167 * Setuid Programs:: Programs running with root privileges.
168 * X.509 Certificates:: Authenticating HTTPS servers.
169 * Name Service Switch:: Configuring libc's name service switch.
170 * Initial RAM Disk:: Linux-Libre bootstrapping.
171 * GRUB Configuration:: Configuring the boot loader.
172 * Invoking guix system:: Instantiating a system configuration.
173 * Defining Services:: Adding new service definitions.
177 * Base Services:: Essential system services.
178 * Networking Services:: Network setup, SSH daemon, etc.
179 * X Window:: Graphical display.
180 * Desktop Services:: D-Bus and desktop services.
181 * Database Services:: SQL databases.
182 * Various Services:: Other services.
186 * Software Freedom:: What may go into the distribution.
187 * Package Naming:: What's in a name?
188 * Version Numbers:: When the name is not enough.
189 * Python Modules:: Taming the snake.
190 * Perl Modules:: Little pearls.
191 * Fonts:: Fond of fonts.
195 * Building from Git:: The latest and greatest.
196 * Running Guix Before It Is Installed:: Hacker tricks.
197 * The Perfect Setup:: The right tools.
198 * Coding Style:: Hygiene of the contributor.
199 * Submitting Patches:: Share your work.
203 * Programming Paradigm:: How to compose your elements.
204 * Modules:: Where to store your code?
205 * Data Types and Pattern Matching:: Implementing data structures.
206 * Formatting Code:: Writing conventions.
211 @c *********************************************************************
213 @chapter Introduction
215 GNU Guix@footnote{``Guix'' is pronounced like ``geeks'', or ``ɡiːks''
216 using the international phonetic alphabet (IPA).} is a functional
217 package management tool for the GNU system. Package management consists
218 of all activities that relate to building packages from sources,
219 honoring their build-time and run-time dependencies,
220 installing packages in user environments, upgrading installed packages
221 to new versions or rolling back to a previous set, removing unused
222 software packages, etc.
224 @cindex functional package management
225 The term @dfn{functional} refers to a specific package management
226 discipline. In Guix, the package build and installation process is seen
227 as a function, in the mathematical sense. That function takes inputs,
228 such as build scripts, a compiler, and libraries, and
229 returns an installed package. As a pure function, its result depends
230 solely on its inputs---for instance, it cannot refer to software or
231 scripts that were not explicitly passed as inputs. A build function
232 always produces the same result when passed a given set of inputs. It
233 cannot alter the system's environment in
234 any way; for instance, it cannot create, modify, or delete files outside
235 of its build and installation directories. This is achieved by running
236 build processes in isolated environments (or @dfn{containers}), where only their
237 explicit inputs are visible.
240 The result of package build functions is @dfn{cached} in the file
241 system, in a special directory called @dfn{the store} (@pxref{The
242 Store}). Each package is installed in a directory of its own, in the
243 store---by default under @file{/gnu/store}. The directory name contains
244 a hash of all the inputs used to build that package; thus, changing an
245 input yields a different directory name.
247 This approach is the foundation of Guix's salient features: support for
248 transactional package upgrade and rollback, per-user installation, and
249 garbage collection of packages (@pxref{Features}).
251 Guix has a command-line interface, which allows users to build, install,
252 upgrade, and remove packages, as well as a Scheme programming interface.
254 @cindex Guix System Distribution
256 Last but not least, Guix is used to build a distribution of the GNU
257 system, with many GNU and non-GNU free software packages. The Guix
258 System Distribution, or GNU@tie{}GuixSD, takes advantage of the core
259 properties of Guix at the system level. With GuixSD, users
260 @emph{declare} all aspects of the operating system configuration, and
261 Guix takes care of instantiating that configuration in a reproducible,
262 stateless fashion. @xref{GNU Distribution}.
264 @c *********************************************************************
266 @chapter Installation
268 GNU Guix is available for download from its website at
269 @url{http://www.gnu.org/software/guix/}. This section describes the
270 software requirements of Guix, as well as how to install it and get
273 Note that this section is concerned with the installation of the package
274 manager, which can be done on top of a running GNU/Linux system. If,
275 instead, you want to install the complete GNU operating system,
276 @pxref{System Installation}.
279 * Binary Installation:: Getting Guix running in no time!
280 * Requirements:: Software needed to build and run Guix.
281 * Running the Test Suite:: Testing Guix.
282 * Setting Up the Daemon:: Preparing the build daemon's environment.
283 * Invoking guix-daemon:: Running the build daemon.
284 * Application Setup:: Application-specific setup.
287 @node Binary Installation
288 @section Binary Installation
290 This section describes how to install Guix on an arbitrary system from a
291 self-contained tarball providing binaries for Guix and for all its
292 dependencies. This is often quicker than installing from source, which
293 is described in the next sections. The only requirement is to have
296 Installing goes along these lines:
300 Download the binary tarball from
301 @indicateurl{ftp://alpha.gnu.org/gnu/guix/guix-binary-@value{VERSION}.@var{system}.tar.xz}@footnote{As
302 usual, make sure to download the associated @file{.sig} file and to
303 verify the authenticity of the tarball against it!}, where @var{system}
304 is @code{x86_64-linux} for an @code{x86_64} machine already running the
305 kernel Linux, and so on.
312 # tar --warning=no-timestamp -xf \
313 guix-binary-@value{VERSION}.@var{system}.tar.xz
314 # mv var/guix /var/ && mv gnu /
317 This creates @file{/gnu/store} (@pxref{The Store}) and @file{/var/guix}.
318 The latter contains a ready-to-use profile for @code{root} (see next
321 Do @emph{not} unpack the tarball on a working Guix system since that
322 would overwrite its own essential files.
324 The @code{--warning=no-timestamp} option makes sure GNU@tie{}tar does
325 not emit warnings about ``implausibly old time stamps'' (such
326 warnings were triggered by GNU@tie{}tar 1.26 and older; recent
328 They stem from the fact that all the
329 files in the archive have their modification time set to zero (which
330 means January 1st, 1970.) This is done on purpose to make sure the
331 archive content is independent of its creation time, thus making it
335 Make @code{root}'s profile available under @file{~/.guix-profile}:
338 # ln -sf /var/guix/profiles/per-user/root/guix-profile \
343 Create the group and user accounts for build users as explained below
344 (@pxref{Build Environment Setup}).
350 # ~root/.guix-profile/bin/guix-daemon --build-users-group=guixbuild
353 On hosts using the systemd init system, drop
354 @file{~root/.guix-profile/lib/systemd/system/guix-daemon.service} in
355 @file{/etc/systemd/system}.
358 Make the @command{guix} command available to other users on the machine,
362 # mkdir -p /usr/local/bin
364 # ln -s /var/guix/profiles/per-user/root/guix-profile/bin/guix
368 To use substitutes from @code{hydra.gnu.org} (@pxref{Substitutes}),
372 # guix archive --authorize < ~root/.guix-profile/share/guix/hydra.gnu.org.pub
376 And that's it! For additional tips and tricks, @pxref{Application
379 The @code{guix} package must remain available in @code{root}'s
380 profile, or it would become subject to garbage collection---in which
381 case you would find yourself badly handicapped by the lack of the
382 @command{guix} command.
384 The tarball in question can be (re)produced and verified simply by
385 running the following command in the Guix source tree:
388 make guix-binary.@var{system}.tar.xz
393 @section Requirements
395 This section lists requirements when building Guix from source. The
396 build procedure for Guix is the same as for other GNU software, and is
397 not covered here. Please see the files @file{README} and @file{INSTALL}
398 in the Guix source tree for additional details.
400 GNU Guix depends on the following packages:
403 @item @url{http://gnu.org/software/guile/, GNU Guile}, version 2.0.7 or later;
404 @item @url{http://gnupg.org/, GNU libgcrypt};
405 @item @url{http://www.gnu.org/software/make/, GNU Make}.
408 The following dependencies are optional:
413 @url{http://savannah.nongnu.org/projects/guile-json/, Guile-JSON} will
414 allow you to use the @command{guix import pypi} command (@pxref{Invoking
415 guix import}). It is of
416 interest primarily for developers and not for casual users.
418 Installing @uref{http://gnutls.org/, GnuTLS-Guile} will
419 allow you to access @code{https} URLs with the @command{guix download}
420 command (@pxref{Invoking guix download}), the @command{guix import pypi}
421 command, and the @command{guix import cpan} command. This is primarily
422 of interest to developers. @xref{Guile Preparations, how to install the
423 GnuTLS bindings for Guile,, gnutls-guile, GnuTLS-Guile}.
426 Unless @code{--disable-daemon} was passed to @command{configure}, the
427 following packages are also needed:
430 @item @url{http://sqlite.org, SQLite 3};
431 @item @url{http://www.bzip.org, libbz2};
432 @item @url{http://gcc.gnu.org, GCC's g++}, with support for the
436 When a working installation of @url{http://nixos.org/nix/, the Nix package
437 manager} is available, you
438 can instead configure Guix with @code{--disable-daemon}. In that case,
439 Nix replaces the three dependencies above.
441 Guix is compatible with Nix, so it is possible to share the same store
442 between both. To do so, you must pass @command{configure} not only the
443 same @code{--with-store-dir} value, but also the same
444 @code{--localstatedir} value. The latter is essential because it
445 specifies where the database that stores metadata about the store is
446 located, among other things. The default values for Nix are
447 @code{--with-store-dir=/nix/store} and @code{--localstatedir=/nix/var}.
448 Note that @code{--disable-daemon} is not required if
449 your goal is to share the store with Nix.
451 @node Running the Test Suite
452 @section Running the Test Suite
454 After a successful @command{configure} and @code{make} run, it is a good
455 idea to run the test suite. It can help catch issues with the setup or
456 environment, or bugs in Guix itself---and really, reporting test
457 failures is a good way to help improve the software. To run the test
464 Test cases can run in parallel: you can use the @code{-j} option of
465 GNU@tie{}make to speed things up. The first run may take a few minutes
466 on a recent machine; subsequent runs will be faster because the store
467 that is created for test purposes will already have various things in
470 Upon failure, please email @email{bug-guix@@gnu.org} and attach the
471 @file{test-suite.log} file. When @file{tests/@var{something}.scm}
472 fails, please also attach the @file{@var{something}.log} file available
473 in the top-level build directory. Please specify the Guix version being
474 used as well as version numbers of the dependencies
475 (@pxref{Requirements}) in your message.
477 @node Setting Up the Daemon
478 @section Setting Up the Daemon
481 Operations such as building a package or running the garbage collector
482 are all performed by a specialized process, the @dfn{build daemon}, on
483 behalf of clients. Only the daemon may access the store and its
484 associated database. Thus, any operation that manipulates the store
485 goes through the daemon. For instance, command-line tools such as
486 @command{guix package} and @command{guix build} communicate with the
487 daemon (@i{via} remote procedure calls) to instruct it what to do.
489 The following sections explain how to prepare the build daemon's
490 environment. Also @ref{Substitutes}, for information on how to allow
491 the daemon to download pre-built binaries.
494 * Build Environment Setup:: Preparing the isolated build environment.
495 * Daemon Offload Setup:: Offloading builds to remote machines.
498 @node Build Environment Setup
499 @subsection Build Environment Setup
501 In a standard multi-user setup, Guix and its daemon---the
502 @command{guix-daemon} program---are installed by the system
503 administrator; @file{/gnu/store} is owned by @code{root} and
504 @command{guix-daemon} runs as @code{root}. Unprivileged users may use
505 Guix tools to build packages or otherwise access the store, and the
506 daemon will do it on their behalf, ensuring that the store is kept in a
507 consistent state, and allowing built packages to be shared among users.
510 When @command{guix-daemon} runs as @code{root}, you may not want package
511 build processes themselves to run as @code{root} too, for obvious
512 security reasons. To avoid that, a special pool of @dfn{build users}
513 should be created for use by build processes started by the daemon.
514 These build users need not have a shell and a home directory: they will
515 just be used when the daemon drops @code{root} privileges in build
516 processes. Having several such users allows the daemon to launch
517 distinct build processes under separate UIDs, which guarantees that they
518 do not interfere with each other---an essential feature since builds are
519 regarded as pure functions (@pxref{Introduction}).
521 On a GNU/Linux system, a build user pool may be created like this (using
522 Bash syntax and the @code{shadow} commands):
524 @c See http://lists.gnu.org/archive/html/bug-guix/2013-01/msg00239.html
525 @c for why `-G' is needed.
527 # groupadd --system guixbuild
528 # for i in `seq -w 1 10`;
530 useradd -g guixbuild -G guixbuild \
531 -d /var/empty -s `which nologin` \
532 -c "Guix build user $i" --system \
538 The number of build users determines how many build jobs may run in
539 parallel, as specified by the @option{--max-jobs} option
540 (@pxref{Invoking guix-daemon, @option{--max-jobs}}). The
541 @code{guix-daemon} program may then be run as @code{root} with the
542 following command@footnote{If your machine uses the systemd init system,
543 dropping the @file{@var{prefix}/lib/systemd/system/guix-daemon.service}
544 file in @file{/etc/systemd/system} will ensure that
545 @command{guix-daemon} is automatically started.}:
548 # guix-daemon --build-users-group=guixbuild
553 This way, the daemon starts build processes in a chroot, under one of
554 the @code{guixbuilder} users. On GNU/Linux, by default, the chroot
555 environment contains nothing but:
557 @c Keep this list in sync with libstore/build.cc! -----------------------
560 a minimal @code{/dev} directory, created mostly independently from the
561 host @code{/dev}@footnote{``Mostly'', because while the set of files
562 that appear in the chroot's @code{/dev} is fixed, most of these files
563 can only be created if the host has them.};
566 the @code{/proc} directory; it only shows the container's processes
567 since a separate PID name space is used;
570 @file{/etc/passwd} with an entry for the current user and an entry for
574 @file{/etc/group} with an entry for the user's group;
577 @file{/etc/hosts} with an entry that maps @code{localhost} to
581 a writable @file{/tmp} directory.
584 If you are installing Guix as an unprivileged user, it is still possible
585 to run @command{guix-daemon} provided you pass @code{--disable-chroot}.
586 However, build processes will not be isolated from one another, and not
587 from the rest of the system. Thus, build processes may interfere with
588 each other, and may access programs, libraries, and other files
589 available on the system---making it much harder to view them as
590 @emph{pure} functions.
593 @node Daemon Offload Setup
594 @subsection Using the Offload Facility
598 When desired, the build daemon can @dfn{offload}
599 derivation builds to other machines
600 running Guix, using the @code{offload} @dfn{build hook}. When that
601 feature is enabled, a list of user-specified build machines is read from
602 @file{/etc/guix/machines.scm}; anytime a build is requested, for
603 instance via @code{guix build}, the daemon attempts to offload it to one
604 of the machines that satisfies the derivation's constraints, in
605 particular its system type---e.g., @file{x86_64-linux}. Missing
606 prerequisites for the build are copied over SSH to the target machine,
607 which then proceeds with the build; upon success the output(s) of the
608 build are copied back to the initial machine.
610 The @file{/etc/guix/machines.scm} file typically looks like this:
614 (name "eightysix.example.org")
615 (system "x86_64-linux")
617 (speed 2.)) ; incredibly fast!
620 (name "meeps.example.org")
621 (system "mips64el-linux")
624 (string-append (getenv "HOME")
625 "/.lsh/identity-for-guix"))))
629 In the example above we specify a list of two build machines, one for
630 the @code{x86_64} architecture and one for the @code{mips64el}
633 In fact, this file is---not surprisingly!---a Scheme file that is
634 evaluated when the @code{offload} hook is started. Its return value
635 must be a list of @code{build-machine} objects. While this example
636 shows a fixed list of build machines, one could imagine, say, using
637 DNS-SD to return a list of potential build machines discovered in the
638 local network (@pxref{Introduction, Guile-Avahi,, guile-avahi, Using
639 Avahi in Guile Scheme Programs}). The @code{build-machine} data type is
642 @deftp {Data Type} build-machine
643 This data type represents build machines the daemon may offload builds
644 to. The important fields are:
649 The remote machine's host name.
652 The remote machine's system type---e.g., @code{"x86_64-linux"}.
655 The user account to use when connecting to the remote machine over SSH.
656 Note that the SSH key pair must @emph{not} be passphrase-protected, to
657 allow non-interactive logins.
661 A number of optional fields may be specified:
666 Port number of the machine's SSH server (default: 22).
669 The SSH private key file to use when connecting to the machine.
671 Currently offloading uses GNU@tie{}lsh as its SSH client
672 (@pxref{Invoking lsh,,, GNU lsh Manual}). Thus, the key file here must
673 be an lsh key file. This may change in the future, though.
675 @item parallel-builds
676 The number of builds that may run in parallel on the machine (1 by
680 A ``relative speed factor''. The offload scheduler will tend to prefer
681 machines with a higher speed factor.
684 A list of strings denoting specific features supported by the machine.
685 An example is @code{"kvm"} for machines that have the KVM Linux modules
686 and corresponding hardware support. Derivations can request features by
687 name, and they will be scheduled on matching build machines.
692 The @code{guix} command must be in the search path on the build
693 machines, since offloading works by invoking the @code{guix archive} and
694 @code{guix build} commands. In addition, the Guix modules must be in
695 @code{$GUILE_LOAD_PATH} on the build machine---you can check whether
696 this is the case by running:
699 lsh build-machine guile -c '(use-modules (guix config))'
702 There's one last thing to do once @file{machines.scm} is in place. As
703 explained above, when offloading, files are transferred back and forth
704 between the machine stores. For this to work, you first need to
705 generate a key pair on each machine to allow the daemon to export signed
706 archives of files from the store (@pxref{Invoking guix archive}):
709 # guix archive --generate-key
713 Each build machine must authorize the key of the master machine so that
714 it accepts store items it receives from the master:
717 # guix archive --authorize < master-public-key.txt
721 Likewise, the master machine must authorize the key of each build machine.
723 All the fuss with keys is here to express pairwise mutual trust
724 relations between the master and the build machines. Concretely, when
725 the master receives files from a build machine (and @i{vice versa}), its
726 build daemon can make sure they are genuine, have not been tampered
727 with, and that they are signed by an authorized key.
730 @node Invoking guix-daemon
731 @section Invoking @command{guix-daemon}
733 The @command{guix-daemon} program implements all the functionality to
734 access the store. This includes launching build processes, running the
735 garbage collector, querying the availability of a build result, etc. It
736 is normally run as @code{root} like this:
739 # guix-daemon --build-users-group=guixbuild
743 For details on how to set it up, @pxref{Setting Up the Daemon}.
746 @cindex container, build environment
747 @cindex build environment
748 @cindex reproducible builds
749 By default, @command{guix-daemon} launches build processes under
750 different UIDs, taken from the build group specified with
751 @code{--build-users-group}. In addition, each build process is run in a
752 chroot environment that only contains the subset of the store that the
753 build process depends on, as specified by its derivation
754 (@pxref{Programming Interface, derivation}), plus a set of specific
755 system directories. By default, the latter contains @file{/dev} and
756 @file{/dev/pts}. Furthermore, on GNU/Linux, the build environment is a
757 @dfn{container}: in addition to having its own file system tree, it has
758 a separate mount name space, its own PID name space, network name space,
759 etc. This helps achieve reproducible builds (@pxref{Features}).
761 When the daemon performs a build on behalf of the user, it creates a
762 build directory under @file{/tmp} or under the directory specified by
763 its @code{TMPDIR} environment variable; this directory is shared with
764 the container for the duration of the build. Be aware that using a
765 directory other than @file{/tmp} can affect build results---for example,
766 with a longer directory name, a build process that uses Unix-domain
767 sockets might hit the name length limitation for @code{sun_path}, which
768 it would otherwise not hit.
770 The build directory is automatically deleted upon completion, unless the
771 build failed and the client specified @option{--keep-failed}
772 (@pxref{Invoking guix build, @option{--keep-failed}}).
774 The following command-line options are supported:
777 @item --build-users-group=@var{group}
778 Take users from @var{group} to run build processes (@pxref{Setting Up
779 the Daemon, build users}).
781 @item --no-substitutes
783 Do not use substitutes for build products. That is, always build things
784 locally instead of allowing downloads of pre-built binaries
785 (@pxref{Substitutes}).
787 By default substitutes are used, unless the client---such as the
788 @command{guix package} command---is explicitly invoked with
789 @code{--no-substitutes}.
791 When the daemon runs with @code{--no-substitutes}, clients can still
792 explicitly enable substitution @i{via} the @code{set-build-options}
793 remote procedure call (@pxref{The Store}).
795 @item --substitute-urls=@var{urls}
796 @anchor{daemon-substitute-urls}
797 Consider @var{urls} the default whitespace-separated list of substitute
798 source URLs. When this option is omitted, @indicateurl{http://hydra.gnu.org}
801 This means that substitutes may be downloaded from @var{urls}, as long
802 as they are signed by a trusted signature (@pxref{Substitutes}).
805 @item --no-build-hook
806 Do not use the @dfn{build hook}.
808 The build hook is a helper program that the daemon can start and to
809 which it submits build requests. This mechanism is used to offload
810 builds to other machines (@pxref{Daemon Offload Setup}).
812 @item --cache-failures
813 Cache build failures. By default, only successful builds are cached.
815 @item --cores=@var{n}
817 Use @var{n} CPU cores to build each derivation; @code{0} means as many
820 The default value is @code{0}, but it may be overridden by clients, such
821 as the @code{--cores} option of @command{guix build} (@pxref{Invoking
824 The effect is to define the @code{NIX_BUILD_CORES} environment variable
825 in the build process, which can then use it to exploit internal
826 parallelism---for instance, by running @code{make -j$NIX_BUILD_CORES}.
828 @item --max-jobs=@var{n}
830 Allow at most @var{n} build jobs in parallel. The default value is
831 @code{1}. Setting it to @code{0} means that no builds will be performed
832 locally; instead, the daemon will offload builds (@pxref{Daemon Offload
833 Setup}), or simply fail.
836 Produce debugging output.
838 This is useful to debug daemon start-up issues, but then it may be
839 overridden by clients, for example the @code{--verbosity} option of
840 @command{guix build} (@pxref{Invoking guix build}).
842 @item --chroot-directory=@var{dir}
843 Add @var{dir} to the build chroot.
845 Doing this may change the result of build processes---for instance if
846 they use optional dependencies found in @var{dir} when it is available,
847 and not otherwise. For that reason, it is not recommended to do so.
848 Instead, make sure that each derivation declares all the inputs that it
851 @item --disable-chroot
852 Disable chroot builds.
854 Using this option is not recommended since, again, it would allow build
855 processes to gain access to undeclared dependencies. It is necessary,
856 though, when @command{guix-daemon} is running under an unprivileged user
859 @item --disable-log-compression
860 Disable compression of the build logs.
862 Unless @code{--lose-logs} is used, all the build logs are kept in the
863 @var{localstatedir}. To save space, the daemon automatically compresses
864 them with bzip2 by default. This option disables that.
866 @item --disable-deduplication
867 @cindex deduplication
868 Disable automatic file ``deduplication'' in the store.
870 By default, files added to the store are automatically ``deduplicated'':
871 if a newly added file is identical to another one found in the store,
872 the daemon makes the new file a hard link to the other file. This can
873 noticeably reduce disk usage, at the expense of slightly increased
874 input/output load at the end of a build process. This option disables
877 @item --gc-keep-outputs[=yes|no]
878 Tell whether the garbage collector (GC) must keep outputs of live
881 When set to ``yes'', the GC will keep the outputs of any live derivation
882 available in the store---the @code{.drv} files. The default is ``no'',
883 meaning that derivation outputs are kept only if they are GC roots.
885 @item --gc-keep-derivations[=yes|no]
886 Tell whether the garbage collector (GC) must keep derivations
887 corresponding to live outputs.
889 When set to ``yes'', as is the case by default, the GC keeps
890 derivations---i.e., @code{.drv} files---as long as at least one of their
891 outputs is live. This allows users to keep track of the origins of
892 items in their store. Setting it to ``no'' saves a bit of disk space.
894 Note that when both @code{--gc-keep-derivations} and
895 @code{--gc-keep-outputs} are used, the effect is to keep all the build
896 prerequisites (the sources, compiler, libraries, and other build-time
897 tools) of live objects in the store, regardless of whether these
898 prerequisites are live. This is convenient for developers since it
899 saves rebuilds or downloads.
901 @item --impersonate-linux-2.6
902 On Linux-based systems, impersonate Linux 2.6. This means that the
903 kernel's @code{uname} system call will report 2.6 as the release number.
905 This might be helpful to build programs that (usually wrongfully) depend
906 on the kernel version number.
909 Do not keep build logs. By default they are kept under
910 @code{@var{localstatedir}/guix/log}.
912 @item --system=@var{system}
913 Assume @var{system} as the current system type. By default it is the
914 architecture/kernel pair found at configure time, such as
917 @item --listen=@var{socket}
918 Listen for connections on @var{socket}, the file name of a Unix-domain
919 socket. The default socket is
920 @file{@var{localstatedir}/daemon-socket/socket}. This option is only
921 useful in exceptional circumstances, such as if you need to run several
922 daemons on the same machine.
926 @node Application Setup
927 @section Application Setup
929 When using Guix on top of GNU/Linux distribution other than GuixSD, a
930 few additional steps are needed to get everything in place. Here are
935 @cindex locales, when not on GuixSD
936 Packages installed @i{via} Guix will not use the host system's locale
937 data. Instead, you must first install one of the locale packages
938 available with Guix and then define the @code{LOCPATH} environment
939 variable (@pxref{Locale Names, @code{LOCPATH},, libc, The GNU C Library
943 $ guix package -i glibc-locales
944 $ export LOCPATH=$HOME/.guix-profile/lib/locale
947 Note that the @code{glibc-locales} package contains data for all the
948 locales supported by the GNU@tie{}libc and weighs in at around
949 110@tie{}MiB. Alternately, the @code{glibc-utf8-locales} is smaller but
950 limited to a few UTF-8 locales.
952 @subsection X11 Fonts
954 The majority of graphical applications use Fontconfig to locate and
955 load fonts and perform X11-client-side rendering. Guix's
956 @code{fontconfig} package looks for fonts in @file{$HOME/.guix-profile}
957 by default. Thus, to allow graphical applications installed with Guix
958 to display fonts, you will have to install fonts with Guix as well.
959 Essential font packages include @code{gs-fonts}, @code{font-dejavu}, and
960 @code{font-gnu-freefont-ttf}.
964 @c *********************************************************************
965 @node Package Management
966 @chapter Package Management
968 The purpose of GNU Guix is to allow users to easily install, upgrade, and
969 remove software packages, without having to know about their build
970 procedure or dependencies. Guix also goes beyond this obvious set of
973 This chapter describes the main features of Guix, as well as the package
974 management tools it provides. Two user interfaces are provided for
975 routine package management tasks: A command-line interface described below
976 (@pxref{Invoking guix package, @code{guix package}}), as well as a visual user
977 interface in Emacs described in a subsequent chapter (@pxref{Emacs Interface}).
980 * Features:: How Guix will make your life brighter.
981 * Invoking guix package:: Package installation, removal, etc.
982 * Substitutes:: Downloading pre-built binaries.
983 * Packages with Multiple Outputs:: Single source package, multiple outputs.
984 * Invoking guix gc:: Running the garbage collector.
985 * Invoking guix pull:: Fetching the latest Guix and distribution.
986 * Invoking guix archive:: Exporting and importing store files.
992 When using Guix, each package ends up in the @dfn{package store}, in its
993 own directory---something that resembles
994 @file{/gnu/store/xxx-package-1.2}, where @code{xxx} is a base32 string
995 (note that Guix comes with an Emacs extension to shorten those file
996 names, @pxref{Emacs Prettify}.)
998 Instead of referring to these directories, users have their own
999 @dfn{profile}, which points to the packages that they actually want to
1000 use. These profiles are stored within each user's home directory, at
1001 @code{$HOME/.guix-profile}.
1003 For example, @code{alice} installs GCC 4.7.2. As a result,
1004 @file{/home/alice/.guix-profile/bin/gcc} points to
1005 @file{/gnu/store/@dots{}-gcc-4.7.2/bin/gcc}. Now, on the same machine,
1006 @code{bob} had already installed GCC 4.8.0. The profile of @code{bob}
1007 simply continues to point to
1008 @file{/gnu/store/@dots{}-gcc-4.8.0/bin/gcc}---i.e., both versions of GCC
1009 coexist on the same system without any interference.
1011 The @command{guix package} command is the central tool to manage
1012 packages (@pxref{Invoking guix package}). It operates on those per-user
1013 profiles, and can be used @emph{with normal user privileges}.
1015 The command provides the obvious install, remove, and upgrade
1016 operations. Each invocation is actually a @emph{transaction}: either
1017 the specified operation succeeds, or nothing happens. Thus, if the
1018 @command{guix package} process is terminated during the transaction,
1019 or if a power outage occurs during the transaction, then the user's
1020 profile remains in its previous state, and remains usable.
1022 In addition, any package transaction may be @emph{rolled back}. So, if,
1023 for example, an upgrade installs a new version of a package that turns
1024 out to have a serious bug, users may roll back to the previous instance
1025 of their profile, which was known to work well. Similarly, the global
1026 system configuration is subject to transactional upgrades and roll-back
1027 (@pxref{Using the Configuration System}).
1029 All those packages in the package store may be @emph{garbage-collected}.
1030 Guix can determine which packages are still referenced by the user
1031 profiles, and remove those that are provably no longer referenced
1032 (@pxref{Invoking guix gc}). Users may also explicitly remove old
1033 generations of their profile so that the packages they refer to can be
1036 @cindex reproducibility
1037 @cindex reproducible builds
1038 Finally, Guix takes a @dfn{purely functional} approach to package
1039 management, as described in the introduction (@pxref{Introduction}).
1040 Each @file{/gnu/store} package directory name contains a hash of all the
1041 inputs that were used to build that package---compiler, libraries, build
1042 scripts, etc. This direct correspondence allows users to make sure a
1043 given package installation matches the current state of their
1044 distribution. It also helps maximize @dfn{build reproducibility}:
1045 thanks to the isolated build environments that are used, a given build
1046 is likely to yield bit-identical files when performed on different
1047 machines (@pxref{Invoking guix-daemon, container}).
1050 This foundation allows Guix to support @dfn{transparent binary/source
1051 deployment}. When a pre-built binary for a @file{/gnu/store} item is
1052 available from an external source---a @dfn{substitute}, Guix just
1053 downloads it and unpacks it;
1054 otherwise, it builds the package from source, locally
1055 (@pxref{Substitutes}).
1057 Control over the build environment is a feature that is also useful for
1058 developers. The @command{guix environment} command allows developers of
1059 a package to quickly set up the right development environment for their
1060 package, without having to manually install the package's dependencies
1061 in their profile (@pxref{Invoking guix environment}).
1063 @node Invoking guix package
1064 @section Invoking @command{guix package}
1066 The @command{guix package} command is the tool that allows users to
1067 install, upgrade, and remove packages, as well as rolling back to
1068 previous configurations. It operates only on the user's own profile,
1069 and works with normal user privileges (@pxref{Features}). Its syntax
1073 guix package @var{options}
1076 Primarily, @var{options} specifies the operations to be performed during
1077 the transaction. Upon completion, a new profile is created, but
1078 previous @dfn{generations} of the profile remain available, should the user
1081 For example, to remove @code{lua} and install @code{guile} and
1082 @code{guile-cairo} in a single transaction:
1085 guix package -r lua -i guile guile-cairo
1088 @command{guix package} also supports a @dfn{declarative approach}
1089 whereby the user specifies the exact set of packages to be available and
1090 passes it @i{via} the @option{--manifest} option
1091 (@pxref{profile-manifest, @option{--manifest}}).
1093 For each user, a symlink to the user's default profile is automatically
1094 created in @file{$HOME/.guix-profile}. This symlink always points to the
1095 current generation of the user's default profile. Thus, users can add
1096 @file{$HOME/.guix-profile/bin} to their @code{PATH} environment
1097 variable, and so on.
1098 @cindex search paths
1099 If you are not using the Guix System Distribution, consider adding the
1100 following lines to your @file{~/.bash_profile} (@pxref{Bash Startup
1101 Files,,, bash, The GNU Bash Reference Manual}) so that newly-spawned
1102 shells get all the right environment variable definitions:
1105 GUIX_PROFILE="$HOME/.guix-profile" \
1106 source "$HOME/.guix-profile/etc/profile"
1109 In a multi-user setup, user profiles are stored in a place registered as
1110 a @dfn{garbage-collector root}, which @file{$HOME/.guix-profile} points
1111 to (@pxref{Invoking guix gc}). That directory is normally
1112 @code{@var{localstatedir}/profiles/per-user/@var{user}}, where
1113 @var{localstatedir} is the value passed to @code{configure} as
1114 @code{--localstatedir}, and @var{user} is the user name. The
1115 @file{per-user} directory is created when @command{guix-daemon} is
1116 started, and the @var{user} sub-directory is created by @command{guix
1119 The @var{options} can be among the following:
1123 @item --install=@var{package} @dots{}
1124 @itemx -i @var{package} @dots{}
1125 Install the specified @var{package}s.
1127 Each @var{package} may specify either a simple package name, such as
1128 @code{guile}, or a package name followed by a hyphen and version number,
1129 such as @code{guile-1.8.8} or simply @code{guile-1.8} (in the latter
1130 case, the newest version prefixed by @code{1.8} is selected.)
1132 If no version number is specified, the
1133 newest available version will be selected. In addition, @var{package}
1134 may contain a colon, followed by the name of one of the outputs of the
1135 package, as in @code{gcc:doc} or @code{binutils-2.22:lib}
1136 (@pxref{Packages with Multiple Outputs}). Packages with a corresponding
1137 name (and optionally version) are searched for among the GNU
1138 distribution modules (@pxref{Package Modules}).
1140 @cindex propagated inputs
1141 Sometimes packages have @dfn{propagated inputs}: these are dependencies
1142 that automatically get installed along with the required package
1143 (@pxref{package-propagated-inputs, @code{propagated-inputs} in
1144 @code{package} objects}, for information about propagated inputs in
1145 package definitions).
1147 @anchor{package-cmd-propagated-inputs}
1148 An example is the GNU MPC library: its C header files refer to those of
1149 the GNU MPFR library, which in turn refer to those of the GMP library.
1150 Thus, when installing MPC, the MPFR and GMP libraries also get installed
1151 in the profile; removing MPC also removes MPFR and GMP---unless they had
1152 also been explicitly installed independently.
1154 Besides, packages sometimes rely on the definition of environment
1155 variables for their search paths (see explanation of
1156 @code{--search-paths} below). Any missing or possibly incorrect
1157 environment variable definitions are reported here.
1159 @c XXX: keep me up-to-date
1160 Finally, when installing a GNU package, the tool reports the
1161 availability of a newer upstream version. In the future, it may provide
1162 the option of installing directly from the upstream version, even if
1163 that version is not yet in the distribution.
1165 @item --install-from-expression=@var{exp}
1167 Install the package @var{exp} evaluates to.
1169 @var{exp} must be a Scheme expression that evaluates to a
1170 @code{<package>} object. This option is notably useful to disambiguate
1171 between same-named variants of a package, with expressions such as
1172 @code{(@@ (gnu packages base) guile-final)}.
1174 Note that this option installs the first output of the specified
1175 package, which may be insufficient when needing a specific output of a
1176 multiple-output package.
1178 @item --install-from-file=@var{file}
1179 @itemx -f @var{file}
1180 Install the package that the code within @var{file} evaluates to.
1182 As an example, @var{file} might contain a definition like this
1183 (@pxref{Defining Packages}):
1186 @verbatiminclude package-hello.scm
1189 Developers may find it useful to include such a @file{package.scm} file
1190 in the root of their project's source tree that can be used to test
1191 development snapshots and create reproducible development environments
1192 (@pxref{Invoking guix environment}).
1194 @item --remove=@var{package} @dots{}
1195 @itemx -r @var{package} @dots{}
1196 Remove the specified @var{package}s.
1198 As for @code{--install}, each @var{package} may specify a version number
1199 and/or output name in addition to the package name. For instance,
1200 @code{-r glibc:debug} would remove the @code{debug} output of
1203 @item --upgrade[=@var{regexp} @dots{}]
1204 @itemx -u [@var{regexp} @dots{}]
1205 Upgrade all the installed packages. If one or more @var{regexp}s are
1206 specified, upgrade only installed packages whose name matches a
1207 @var{regexp}. Also see the @code{--do-not-upgrade} option below.
1209 Note that this upgrades package to the latest version of packages found
1210 in the distribution currently installed. To update your distribution,
1211 you should regularly run @command{guix pull} (@pxref{Invoking guix
1214 @item --do-not-upgrade[=@var{regexp} @dots{}]
1215 When used together with the @code{--upgrade} option, do @emph{not}
1216 upgrade any packages whose name matches a @var{regexp}. For example, to
1217 upgrade all packages in the current profile except those containing the
1218 substring ``emacs'':
1221 $ guix package --upgrade . --do-not-upgrade emacs
1224 @item @anchor{profile-manifest}--manifest=@var{file}
1225 @itemx -m @var{file}
1226 @cindex profile declaration
1227 @cindex profile manifest
1228 Create a new generation of the profile from the manifest object
1229 returned by the Scheme code in @var{file}.
1231 This allows you to @emph{declare} the profile's contents rather than
1232 constructing it through a sequence of @code{--install} and similar
1233 commands. The advantage is that @var{file} can be put under version
1234 control, copied to different machines to reproduce the same profile, and
1237 @c FIXME: Add reference to (guix profile) documentation when available.
1238 @var{file} must return a @dfn{manifest} object, which is roughly a list
1241 @findex packages->manifest
1243 (use-package-modules guile emacs)
1248 ;; Use a specific package output.
1249 (list guile-2.0 "debug")))
1253 Roll back to the previous @dfn{generation} of the profile---i.e., undo
1254 the last transaction.
1256 When combined with options such as @code{--install}, roll back occurs
1257 before any other actions.
1259 When rolling back from the first generation that actually contains
1260 installed packages, the profile is made to point to the @dfn{zeroth
1261 generation}, which contains no files apart from its own meta-data.
1263 Installing, removing, or upgrading packages from a generation that has
1264 been rolled back to overwrites previous future generations. Thus, the
1265 history of a profile's generations is always linear.
1267 @item --switch-generation=@var{pattern}
1268 @itemx -S @var{pattern}
1269 Switch to a particular generation defined by @var{pattern}.
1271 @var{pattern} may be either a generation number or a number prefixed
1272 with ``+'' or ``-''. The latter means: move forward/backward by a
1273 specified number of generations. For example, if you want to return to
1274 the latest generation after @code{--roll-back}, use
1275 @code{--switch-generation=+1}.
1277 The difference between @code{--roll-back} and
1278 @code{--switch-generation=-1} is that @code{--switch-generation} will
1279 not make a zeroth generation, so if a specified generation does not
1280 exist, the current generation will not be changed.
1282 @item --search-paths[=@var{kind}]
1283 @cindex search paths
1284 Report environment variable definitions, in Bash syntax, that may be
1285 needed in order to use the set of installed packages. These environment
1286 variables are used to specify @dfn{search paths} for files used by some
1287 of the installed packages.
1289 For example, GCC needs the @code{CPATH} and @code{LIBRARY_PATH}
1290 environment variables to be defined so it can look for headers and
1291 libraries in the user's profile (@pxref{Environment Variables,,, gcc,
1292 Using the GNU Compiler Collection (GCC)}). If GCC and, say, the C
1293 library are installed in the profile, then @code{--search-paths} will
1294 suggest setting these variables to @code{@var{profile}/include} and
1295 @code{@var{profile}/lib}, respectively.
1297 The typical use case is to define these environment variables in the
1301 $ eval `guix package --search-paths`
1304 @var{kind} may be one of @code{exact}, @code{prefix}, or @code{suffix},
1305 meaning that the returned environment variable definitions will either
1306 be exact settings, or prefixes or suffixes of the current value of these
1307 variables. When omitted, @var{kind} defaults to @code{exact}.
1309 @item --profile=@var{profile}
1310 @itemx -p @var{profile}
1311 Use @var{profile} instead of the user's default profile.
1314 Produce verbose output. In particular, emit the environment's build log
1315 on the standard error port.
1318 Use the bootstrap Guile to build the profile. This option is only
1319 useful to distribution developers.
1323 In addition to these actions @command{guix package} supports the
1324 following options to query the current state of a profile, or the
1325 availability of packages:
1329 @item --search=@var{regexp}
1330 @itemx -s @var{regexp}
1331 List the available packages whose name, synopsis, or description matches
1332 @var{regexp}. Print all the meta-data of matching packages in
1333 @code{recutils} format (@pxref{Top, GNU recutils databases,, recutils,
1334 GNU recutils manual}).
1336 This allows specific fields to be extracted using the @command{recsel}
1337 command, for instance:
1340 $ guix package -s malloc | recsel -p name,version
1348 Similarly, to show the name of all the packages available under the
1349 terms of the GNU@tie{}LGPL version 3:
1352 $ guix package -s "" | recsel -p name -e 'license ~ "LGPL 3"'
1359 @item --show=@var{package}
1360 Show details about @var{package}, taken from the list of available packages, in
1361 @code{recutils} format (@pxref{Top, GNU recutils databases,, recutils, GNU
1365 $ guix package --show=python | recsel -p name,version
1373 You may also specify the full name of a package to only get details about a
1374 specific version of it:
1376 $ guix package --show=python-3.3.5 | recsel -p name,version
1383 @item --list-installed[=@var{regexp}]
1384 @itemx -I [@var{regexp}]
1385 List the currently installed packages in the specified profile, with the
1386 most recently installed packages shown last. When @var{regexp} is
1387 specified, list only installed packages whose name matches @var{regexp}.
1389 For each installed package, print the following items, separated by
1390 tabs: the package name, its version string, the part of the package that
1391 is installed (for instance, @code{out} for the default output,
1392 @code{include} for its headers, etc.), and the path of this package in
1395 @item --list-available[=@var{regexp}]
1396 @itemx -A [@var{regexp}]
1397 List packages currently available in the distribution for this system
1398 (@pxref{GNU Distribution}). When @var{regexp} is specified, list only
1399 installed packages whose name matches @var{regexp}.
1401 For each package, print the following items separated by tabs: its name,
1402 its version string, the parts of the package (@pxref{Packages with
1403 Multiple Outputs}), and the source location of its definition.
1405 @item --list-generations[=@var{pattern}]
1406 @itemx -l [@var{pattern}]
1407 Return a list of generations along with their creation dates; for each
1408 generation, show the installed packages, with the most recently
1409 installed packages shown last. Note that the zeroth generation is never
1412 For each installed package, print the following items, separated by
1413 tabs: the name of a package, its version string, the part of the package
1414 that is installed (@pxref{Packages with Multiple Outputs}), and the
1415 location of this package in the store.
1417 When @var{pattern} is used, the command returns only matching
1418 generations. Valid patterns include:
1421 @item @emph{Integers and comma-separated integers}. Both patterns denote
1422 generation numbers. For instance, @code{--list-generations=1} returns
1425 And @code{--list-generations=1,8,2} outputs three generations in the
1426 specified order. Neither spaces nor trailing commas are allowed.
1428 @item @emph{Ranges}. @code{--list-generations=2..9} prints the
1429 specified generations and everything in between. Note that the start of
1430 a range must be lesser than its end.
1432 It is also possible to omit the endpoint. For example,
1433 @code{--list-generations=2..}, returns all generations starting from the
1436 @item @emph{Durations}. You can also get the last @emph{N}@tie{}days, weeks,
1437 or months by passing an integer along with the first letter of the
1438 duration. For example, @code{--list-generations=20d} lists generations
1439 that are up to 20 days old.
1442 @item --delete-generations[=@var{pattern}]
1443 @itemx -d [@var{pattern}]
1444 When @var{pattern} is omitted, delete all generations except the current
1447 This command accepts the same patterns as @option{--list-generations}.
1448 When @var{pattern} is specified, delete the matching generations. When
1449 @var{pattern} specifies a duration, generations @emph{older} than the
1450 specified duration match. For instance, @code{--delete-generations=1m}
1451 deletes generations that are more than one month old.
1453 If the current generation matches, it is @emph{not} deleted. Also, the
1454 zeroth generation is never deleted.
1456 Note that deleting generations prevents roll-back to them.
1457 Consequently, this command must be used with care.
1461 Finally, since @command{guix package} may actually start build
1462 processes, it supports all the common build options that @command{guix
1463 build} supports (@pxref{Invoking guix build, common build options}).
1466 @section Substitutes
1469 @cindex pre-built binaries
1470 Guix supports transparent source/binary deployment, which means that it
1471 can either build things locally, or download pre-built items from a
1472 server. We call these pre-built items @dfn{substitutes}---they are
1473 substitutes for local build results. In many cases, downloading a
1474 substitute is much faster than building things locally.
1476 Substitutes can be anything resulting from a derivation build
1477 (@pxref{Derivations}). Of course, in the common case, they are
1478 pre-built package binaries, but source tarballs, for instance, which
1479 also result from derivation builds, can be available as substitutes.
1481 The @code{hydra.gnu.org} server is a front-end to a build farm that
1482 builds packages from the GNU distribution continuously for some
1483 architectures, and makes them available as substitutes. This is the
1484 default source of substitutes; it can be overridden by passing the
1485 @option{--substitute-urls} option either to @command{guix-daemon}
1486 (@pxref{daemon-substitute-urls,, @code{guix-daemon --substitute-urls}})
1487 or to client tools such as @command{guix package}
1488 (@pxref{client-substitute-urls,, client @option{--substitute-urls}
1492 @cindex digital signatures
1493 To allow Guix to download substitutes from @code{hydra.gnu.org}, you
1494 must add its public key to the access control list (ACL) of archive
1495 imports, using the @command{guix archive} command (@pxref{Invoking guix
1496 archive}). Doing so implies that you trust @code{hydra.gnu.org} to not
1497 be compromised and to serve genuine substitutes.
1499 This public key is installed along with Guix, in
1500 @code{@var{prefix}/share/guix/hydra.gnu.org.pub}, where @var{prefix} is
1501 the installation prefix of Guix. If you installed Guix from source,
1502 make sure you checked the GPG signature of
1503 @file{guix-@value{VERSION}.tar.gz}, which contains this public key file.
1504 Then, you can run something like this:
1507 # guix archive --authorize < hydra.gnu.org.pub
1510 Once this is in place, the output of a command like @code{guix build}
1511 should change from something like:
1514 $ guix build emacs --dry-run
1515 The following derivations would be built:
1516 /gnu/store/yr7bnx8xwcayd6j95r2clmkdl1qh688w-emacs-24.3.drv
1517 /gnu/store/x8qsh1hlhgjx6cwsjyvybnfv2i37z23w-dbus-1.6.4.tar.gz.drv
1518 /gnu/store/1ixwp12fl950d15h2cj11c73733jay0z-alsa-lib-1.0.27.1.tar.bz2.drv
1519 /gnu/store/nlma1pw0p603fpfiqy7kn4zm105r5dmw-util-linux-2.21.drv
1527 $ guix build emacs --dry-run
1528 The following files would be downloaded:
1529 /gnu/store/pk3n22lbq6ydamyymqkkz7i69wiwjiwi-emacs-24.3
1530 /gnu/store/2ygn4ncnhrpr61rssa6z0d9x22si0va3-libjpeg-8d
1531 /gnu/store/71yz6lgx4dazma9dwn2mcjxaah9w77jq-cairo-1.12.16
1532 /gnu/store/7zdhgp0n1518lvfn8mb96sxqfmvqrl7v-libxrender-0.9.7
1537 This indicates that substitutes from @code{hydra.gnu.org} are usable and
1538 will be downloaded, when possible, for future builds.
1540 Guix ignores substitutes that are not signed, or that are not signed by
1541 one of the keys listed in the ACL. It also detects and raises an error
1542 when attempting to use a substitute that has been tampered with.
1544 The substitute mechanism can be disabled globally by running
1545 @code{guix-daemon} with @code{--no-substitutes} (@pxref{Invoking
1546 guix-daemon}). It can also be disabled temporarily by passing the
1547 @code{--no-substitutes} option to @command{guix package}, @command{guix
1548 build}, and other command-line tools.
1551 Today, each individual's control over their own computing is at the
1552 mercy of institutions, corporations, and groups with enough power and
1553 determination to subvert the computing infrastructure and exploit its
1554 weaknesses. While using @code{hydra.gnu.org} substitutes can be
1555 convenient, we encourage users to also build on their own, or even run
1556 their own build farm, such that @code{hydra.gnu.org} is less of an
1557 interesting target. One way to help is by publishing the software you
1558 build using @command{guix publish} so that others have one more choice
1559 of server to download substitutes from (@pxref{Invoking guix publish}).
1561 Guix has the foundations to maximize build reproducibility
1562 (@pxref{Features}). In most cases, independent builds of a given
1563 package or derivation should yield bit-identical results. Thus, through
1564 a diverse set of independent package builds, we can strengthen the
1565 integrity of our systems.
1567 In the future, we want Guix to have support to publish and retrieve
1568 binaries to/from other users, in a peer-to-peer fashion. If you would
1569 like to discuss this project, join us on @email{guix-devel@@gnu.org}.
1572 @node Packages with Multiple Outputs
1573 @section Packages with Multiple Outputs
1575 @cindex multiple-output packages
1576 @cindex package outputs
1578 Often, packages defined in Guix have a single @dfn{output}---i.e., the
1579 source package leads exactly one directory in the store. When running
1580 @command{guix package -i glibc}, one installs the default output of the
1581 GNU libc package; the default output is called @code{out}, but its name
1582 can be omitted as shown in this command. In this particular case, the
1583 default output of @code{glibc} contains all the C header files, shared
1584 libraries, static libraries, Info documentation, and other supporting
1587 Sometimes it is more appropriate to separate the various types of files
1588 produced from a single source package into separate outputs. For
1589 instance, the GLib C library (used by GTK+ and related packages)
1590 installs more than 20 MiB of reference documentation as HTML pages.
1591 To save space for users who do not need it, the documentation goes to a
1592 separate output, called @code{doc}. To install the main GLib output,
1593 which contains everything but the documentation, one would run:
1596 guix package -i glib
1599 The command to install its documentation is:
1602 guix package -i glib:doc
1605 Some packages install programs with different ``dependency footprints''.
1606 For instance, the WordNet package install both command-line tools and
1607 graphical user interfaces (GUIs). The former depend solely on the C
1608 library, whereas the latter depend on Tcl/Tk and the underlying X
1609 libraries. In this case, we leave the command-line tools in the default
1610 output, whereas the GUIs are in a separate output. This allows users
1611 who do not need the GUIs to save space. The @command{guix size} command
1612 can help find out about such situations (@pxref{Invoking guix size}).
1613 @command{guix graph} can also be helpful (@pxref{Invoking guix graph}).
1615 There are several such multiple-output packages in the GNU distribution.
1616 Other conventional output names include @code{lib} for libraries and
1617 possibly header files, @code{bin} for stand-alone programs, and
1618 @code{debug} for debugging information (@pxref{Installing Debugging
1619 Files}). The outputs of a packages are listed in the third column of
1620 the output of @command{guix package --list-available} (@pxref{Invoking
1624 @node Invoking guix gc
1625 @section Invoking @command{guix gc}
1627 @cindex garbage collector
1628 Packages that are installed but not used may be @dfn{garbage-collected}.
1629 The @command{guix gc} command allows users to explicitly run the garbage
1630 collector to reclaim space from the @file{/gnu/store} directory. It is
1631 the @emph{only} way to remove files from @file{/gnu/store}---removing
1632 files or directories manually may break it beyond repair!
1634 The garbage collector has a set of known @dfn{roots}: any file under
1635 @file{/gnu/store} reachable from a root is considered @dfn{live} and
1636 cannot be deleted; any other file is considered @dfn{dead} and may be
1637 deleted. The set of garbage collector roots includes default user
1638 profiles, and may be augmented with @command{guix build --root}, for
1639 example (@pxref{Invoking guix build}).
1641 Prior to running @code{guix gc --collect-garbage} to make space, it is
1642 often useful to remove old generations from user profiles; that way, old
1643 package builds referenced by those generations can be reclaimed. This
1644 is achieved by running @code{guix package --delete-generations}
1645 (@pxref{Invoking guix package}).
1647 The @command{guix gc} command has three modes of operation: it can be
1648 used to garbage-collect any dead files (the default), to delete specific
1649 files (the @code{--delete} option), to print garbage-collector
1650 information, or for more advanced queries. The garbage collection
1651 options are as follows:
1654 @item --collect-garbage[=@var{min}]
1655 @itemx -C [@var{min}]
1656 Collect garbage---i.e., unreachable @file{/gnu/store} files and
1657 sub-directories. This is the default operation when no option is
1660 When @var{min} is given, stop once @var{min} bytes have been collected.
1661 @var{min} may be a number of bytes, or it may include a unit as a
1662 suffix, such as @code{MiB} for mebibytes and @code{GB} for gigabytes
1663 (@pxref{Block size, size specifications,, coreutils, GNU Coreutils}).
1665 When @var{min} is omitted, collect all the garbage.
1669 Attempt to delete all the store files and directories specified as
1670 arguments. This fails if some of the files are not in the store, or if
1671 they are still live.
1674 Show the list of dead files and directories still present in the
1675 store---i.e., files and directories no longer reachable from any root.
1678 Show the list of live store files and directories.
1682 In addition, the references among existing store files can be queried:
1688 List the references (respectively, the referrers) of store files given
1694 List the requisites of the store files passed as arguments. Requisites
1695 include the store files themselves, their references, and the references
1696 of these, recursively. In other words, the returned list is the
1697 @dfn{transitive closure} of the store files.
1699 @xref{Invoking guix size}, for a tool to profile the size of an
1700 element's closure. @xref{Invoking guix graph}, for a tool to visualize
1701 the graph of references.
1705 Lastly, the following options allow you to check the integrity of the
1706 store and to control disk usage.
1710 @item --verify[=@var{options}]
1711 @cindex integrity, of the store
1712 @cindex integrity checking
1713 Verify the integrity of the store.
1715 By default, make sure that all the store items marked as valid in the
1716 daemon's database actually exist in @file{/gnu/store}.
1718 When provided, @var{options} must a comma-separated list containing one
1719 or more of @code{contents} and @code{repair}.
1721 When passing @option{--verify=contents}, the daemon will compute the
1722 content hash of each store item and compare it against its hash in the
1723 database. Hash mismatches are reported as data corruptions. Because it
1724 traverses @emph{all the files in the store}, this command can take a
1725 long time, especially on systems with a slow disk drive.
1727 @cindex repairing the store
1728 Using @option{--verify=repair} or @option{--verify=contents,repair}
1729 causes the daemon to try to repair corrupt store items by fetching
1730 substitutes for them (@pxref{Substitutes}). Because repairing is not
1731 atomic, and thus potentially dangerous, it is available only to the
1732 system administrator.
1735 @cindex deduplication
1736 Optimize the store by hard-linking identical files---this is
1737 @dfn{deduplication}.
1739 The daemon performs deduplication after each successful build or archive
1740 import, unless it was started with @code{--disable-deduplication}
1741 (@pxref{Invoking guix-daemon, @code{--disable-deduplication}}). Thus,
1742 this option is primarily useful when the daemon was running with
1743 @code{--disable-deduplication}.
1747 @node Invoking guix pull
1748 @section Invoking @command{guix pull}
1750 Packages are installed or upgraded to the latest version available in
1751 the distribution currently available on your local machine. To update
1752 that distribution, along with the Guix tools, you must run @command{guix
1753 pull}: the command downloads the latest Guix source code and package
1754 descriptions, and deploys it.
1756 On completion, @command{guix package} will use packages and package
1757 versions from this just-retrieved copy of Guix. Not only that, but all
1758 the Guix commands and Scheme modules will also be taken from that latest
1759 version. New @command{guix} sub-commands added by the update also
1762 The @command{guix pull} command is usually invoked with no arguments,
1763 but it supports the following options:
1767 Produce verbose output, writing build logs to the standard error output.
1769 @item --url=@var{url}
1770 Download the source tarball of Guix from @var{url}.
1772 By default, the tarball is taken from its canonical address at
1773 @code{gnu.org}, for the stable branch of Guix.
1776 Use the bootstrap Guile to build the latest Guix. This option is only
1777 useful to Guix developers.
1781 @node Invoking guix archive
1782 @section Invoking @command{guix archive}
1784 The @command{guix archive} command allows users to @dfn{export} files
1785 from the store into a single archive, and to later @dfn{import} them.
1786 In particular, it allows store files to be transferred from one machine
1787 to another machine's store. For example, to transfer the @code{emacs}
1788 package to a machine connected over SSH, one would run:
1791 guix archive --export -r emacs | ssh the-machine guix archive --import
1795 Similarly, a complete user profile may be transferred from one machine
1796 to another like this:
1799 guix archive --export -r $(readlink -f ~/.guix-profile) | \
1800 ssh the-machine guix-archive --import
1804 However, note that, in both examples, all of @code{emacs} and the
1805 profile as well as all of their dependencies are transferred (due to
1806 @code{-r}), regardless of what is already available in the target
1807 machine's store. The @code{--missing} option can help figure out which
1808 items are missing from the target's store.
1810 Archives are stored in the ``Nix archive'' or ``Nar'' format, which is
1811 comparable in spirit to `tar', but with a few noteworthy differences
1812 that make it more appropriate for our purposes. First, rather than
1813 recording all Unix meta-data for each file, the Nar format only mentions
1814 the file type (regular, directory, or symbolic link); Unix permissions
1815 and owner/group are dismissed. Second, the order in which directory
1816 entries are stored always follows the order of file names according to
1817 the C locale collation order. This makes archive production fully
1820 When exporting, the daemon digitally signs the contents of the archive,
1821 and that digital signature is appended. When importing, the daemon
1822 verifies the signature and rejects the import in case of an invalid
1823 signature or if the signing key is not authorized.
1824 @c FIXME: Add xref to daemon doc about signatures.
1826 The main options are:
1830 Export the specified store files or packages (see below.) Write the
1831 resulting archive to the standard output.
1833 Dependencies are @emph{not} included in the output, unless
1834 @code{--recursive} is passed.
1838 When combined with @code{--export}, this instructs @command{guix
1839 archive} to include dependencies of the given items in the archive.
1840 Thus, the resulting archive is self-contained: it contains the closure
1841 of the exported store items.
1844 Read an archive from the standard input, and import the files listed
1845 therein into the store. Abort if the archive has an invalid digital
1846 signature, or if it is signed by a public key not among the authorized
1847 keys (see @code{--authorize} below.)
1850 Read a list of store file names from the standard input, one per line,
1851 and write on the standard output the subset of these files missing from
1854 @item --generate-key[=@var{parameters}]
1855 @cindex signing, archives
1856 Generate a new key pair for the daemons. This is a prerequisite before
1857 archives can be exported with @code{--export}. Note that this operation
1858 usually takes time, because it needs to gather enough entropy to
1859 generate the key pair.
1861 The generated key pair is typically stored under @file{/etc/guix}, in
1862 @file{signing-key.pub} (public key) and @file{signing-key.sec} (private
1863 key, which must be kept secret.) When @var{parameters} is omitted,
1864 an ECDSA key using the Ed25519 curve is generated, or, for Libgcrypt
1865 versions before 1.6.0, it is a 4096-bit RSA key.
1866 Alternately, @var{parameters} can specify
1867 @code{genkey} parameters suitable for Libgcrypt (@pxref{General
1868 public-key related Functions, @code{gcry_pk_genkey},, gcrypt, The
1869 Libgcrypt Reference Manual}).
1872 @cindex authorizing, archives
1873 Authorize imports signed by the public key passed on standard input.
1874 The public key must be in ``s-expression advanced format''---i.e., the
1875 same format as the @file{signing-key.pub} file.
1877 The list of authorized keys is kept in the human-editable file
1878 @file{/etc/guix/acl}. The file contains
1879 @url{http://people.csail.mit.edu/rivest/Sexp.txt, ``advanced-format
1880 s-expressions''} and is structured as an access-control list in the
1881 @url{http://theworld.com/~cme/spki.txt, Simple Public-Key Infrastructure
1885 To export store files as an archive to the standard output, run:
1888 guix archive --export @var{options} @var{specifications}...
1891 @var{specifications} may be either store file names or package
1892 specifications, as for @command{guix package} (@pxref{Invoking guix
1893 package}). For instance, the following command creates an archive
1894 containing the @code{gui} output of the @code{git} package and the main
1895 output of @code{emacs}:
1898 guix archive --export git:gui /gnu/store/...-emacs-24.3 > great.nar
1901 If the specified packages are not built yet, @command{guix archive}
1902 automatically builds them. The build process may be controlled with the
1903 same options that can be passed to the @command{guix build} command
1904 (@pxref{Invoking guix build, common build options}).
1906 @c *********************************************************************
1909 @c *********************************************************************
1910 @node Programming Interface
1911 @chapter Programming Interface
1913 GNU Guix provides several Scheme programming interfaces (APIs) to
1914 define, build, and query packages. The first interface allows users to
1915 write high-level package definitions. These definitions refer to
1916 familiar packaging concepts, such as the name and version of a package,
1917 its build system, and its dependencies. These definitions can then be
1918 turned into concrete build actions.
1920 Build actions are performed by the Guix daemon, on behalf of users. In a
1921 standard setup, the daemon has write access to the store---the
1922 @file{/gnu/store} directory---whereas users do not. The recommended
1923 setup also has the daemon perform builds in chroots, under a specific
1924 build users, to minimize interference with the rest of the system.
1927 Lower-level APIs are available to interact with the daemon and the
1928 store. To instruct the daemon to perform a build action, users actually
1929 provide it with a @dfn{derivation}. A derivation is a low-level
1930 representation of the build actions to be taken, and the environment in
1931 which they should occur---derivations are to package definitions what
1932 assembly is to C programs. The term ``derivation'' comes from the fact
1933 that build results @emph{derive} from them.
1935 This chapter describes all these APIs in turn, starting from high-level
1936 package definitions.
1939 * Defining Packages:: Defining new packages.
1940 * Build Systems:: Specifying how packages are built.
1941 * The Store:: Manipulating the package store.
1942 * Derivations:: Low-level interface to package derivations.
1943 * The Store Monad:: Purely functional interface to the store.
1944 * G-Expressions:: Manipulating build expressions.
1947 @node Defining Packages
1948 @section Defining Packages
1950 The high-level interface to package definitions is implemented in the
1951 @code{(guix packages)} and @code{(guix build-system)} modules. As an
1952 example, the package definition, or @dfn{recipe}, for the GNU Hello
1953 package looks like this:
1956 (define-module (gnu packages hello)
1957 #:use-module (guix packages)
1958 #:use-module (guix download)
1959 #:use-module (guix build-system gnu)
1960 #:use-module (guix licenses)
1961 #:use-module (gnu packages gawk))
1963 (define-public hello
1969 (uri (string-append "mirror://gnu/hello/hello-" version
1972 (base32 "0wqd8sjmxfskrflaxywc7gqw7sfawrfvdxd9skxawzfgyy0pzdz6"))))
1973 (build-system gnu-build-system)
1974 (arguments `(#:configure-flags '("--enable-silent-rules")))
1975 (inputs `(("gawk" ,gawk)))
1976 (synopsis "Hello, GNU world: An example GNU package")
1977 (description "Guess what GNU Hello prints!")
1978 (home-page "http://www.gnu.org/software/hello/")
1983 Without being a Scheme expert, the reader may have guessed the meaning
1984 of the various fields here. This expression binds variable @code{hello}
1985 to a @code{<package>} object, which is essentially a record
1986 (@pxref{SRFI-9, Scheme records,, guile, GNU Guile Reference Manual}).
1987 This package object can be inspected using procedures found in the
1988 @code{(guix packages)} module; for instance, @code{(package-name hello)}
1989 returns---surprise!---@code{"hello"}.
1991 With luck, you may be able to import part or all of the definition of
1992 the package you are interested in from another repository, using the
1993 @code{guix import} command (@pxref{Invoking guix import}).
1995 In the example above, @var{hello} is defined into a module of its own,
1996 @code{(gnu packages hello)}. Technically, this is not strictly
1997 necessary, but it is convenient to do so: all the packages defined in
1998 modules under @code{(gnu packages @dots{})} are automatically known to
1999 the command-line tools (@pxref{Package Modules}).
2001 There are a few points worth noting in the above package definition:
2005 The @code{source} field of the package is an @code{<origin>} object
2006 (@pxref{origin Reference}, for the complete reference).
2007 Here, the @code{url-fetch} method from @code{(guix download)} is used,
2008 meaning that the source is a file to be downloaded over FTP or HTTP.
2010 The @code{mirror://gnu} prefix instructs @code{url-fetch} to use one of
2011 the GNU mirrors defined in @code{(guix download)}.
2013 The @code{sha256} field specifies the expected SHA256 hash of the file
2014 being downloaded. It is mandatory, and allows Guix to check the
2015 integrity of the file. The @code{(base32 @dots{})} form introduces the
2016 base32 representation of the hash. You can obtain this information with
2017 @code{guix download} (@pxref{Invoking guix download}) and @code{guix
2018 hash} (@pxref{Invoking guix hash}).
2021 When needed, the @code{origin} form can also have a @code{patches} field
2022 listing patches to be applied, and a @code{snippet} field giving a
2023 Scheme expression to modify the source code.
2026 @cindex GNU Build System
2027 The @code{build-system} field specifies the procedure to build the
2028 package (@pxref{Build Systems}). Here, @var{gnu-build-system}
2029 represents the familiar GNU Build System, where packages may be
2030 configured, built, and installed with the usual @code{./configure &&
2031 make && make check && make install} command sequence.
2034 The @code{arguments} field specifies options for the build system
2035 (@pxref{Build Systems}). Here it is interpreted by
2036 @var{gnu-build-system} as a request run @file{configure} with the
2037 @code{--enable-silent-rules} flag.
2040 The @code{inputs} field specifies inputs to the build process---i.e.,
2041 build-time or run-time dependencies of the package. Here, we define an
2042 input called @code{"gawk"} whose value is that of the @var{gawk}
2043 variable; @var{gawk} is itself bound to a @code{<package>} object.
2045 Note that GCC, Coreutils, Bash, and other essential tools do not need to
2046 be specified as inputs here. Instead, @var{gnu-build-system} takes care
2047 of ensuring that they are present (@pxref{Build Systems}).
2049 However, any other dependencies need to be specified in the
2050 @code{inputs} field. Any dependency not specified here will simply be
2051 unavailable to the build process, possibly leading to a build failure.
2054 @xref{package Reference}, for a full description of possible fields.
2056 Once a package definition is in place, the
2057 package may actually be built using the @code{guix build} command-line
2058 tool (@pxref{Invoking guix build}). You can easily jump back to the
2059 package definition using the @command{guix edit} command
2060 (@pxref{Invoking guix edit}).
2061 @xref{Packaging Guidelines}, for
2062 more information on how to test package definitions, and
2063 @ref{Invoking guix lint}, for information on how to check a definition
2064 for style conformance.
2066 Eventually, updating the package definition to a new upstream version
2067 can be partly automated by the @command{guix refresh} command
2068 (@pxref{Invoking guix refresh}).
2070 Behind the scenes, a derivation corresponding to the @code{<package>}
2071 object is first computed by the @code{package-derivation} procedure.
2072 That derivation is stored in a @code{.drv} file under @file{/gnu/store}.
2073 The build actions it prescribes may then be realized by using the
2074 @code{build-derivations} procedure (@pxref{The Store}).
2076 @deffn {Scheme Procedure} package-derivation @var{store} @var{package} [@var{system}]
2077 Return the @code{<derivation>} object of @var{package} for @var{system}
2078 (@pxref{Derivations}).
2080 @var{package} must be a valid @code{<package>} object, and @var{system}
2081 must be a string denoting the target system type---e.g.,
2082 @code{"x86_64-linux"} for an x86_64 Linux-based GNU system. @var{store}
2083 must be a connection to the daemon, which operates on the store
2084 (@pxref{The Store}).
2088 @cindex cross-compilation
2089 Similarly, it is possible to compute a derivation that cross-builds a
2090 package for some other system:
2092 @deffn {Scheme Procedure} package-cross-derivation @var{store} @
2093 @var{package} @var{target} [@var{system}]
2094 Return the @code{<derivation>} object of @var{package} cross-built from
2095 @var{system} to @var{target}.
2097 @var{target} must be a valid GNU triplet denoting the target hardware
2098 and operating system, such as @code{"mips64el-linux-gnu"}
2099 (@pxref{Configuration Names, GNU configuration triplets,, configure, GNU
2100 Configure and Build System}).
2104 * package Reference :: The package data type.
2105 * origin Reference:: The origin data type.
2109 @node package Reference
2110 @subsection @code{package} Reference
2112 This section summarizes all the options available in @code{package}
2113 declarations (@pxref{Defining Packages}).
2115 @deftp {Data Type} package
2116 This is the data type representing a package recipe.
2120 The name of the package, as a string.
2122 @item @code{version}
2123 The version of the package, as a string.
2126 An origin object telling how the source code for the package should be
2127 acquired (@pxref{origin Reference}).
2129 @item @code{build-system}
2130 The build system that should be used to build the package (@pxref{Build
2133 @item @code{arguments} (default: @code{'()})
2134 The arguments that should be passed to the build system. This is a
2135 list, typically containing sequential keyword-value pairs.
2137 @item @code{inputs} (default: @code{'()})
2138 Package or derivation inputs to the build. This is a list of lists,
2139 where each list has the name of the input (a string) as its first
2140 element, a package or derivation object as its second element, and
2141 optionally the name of the output of the package or derivation that
2142 should be used, which defaults to @code{"out"}.
2144 @item @anchor{package-propagated-inputs}@code{propagated-inputs} (default: @code{'()})
2145 @cindex propagated inputs
2146 This field is like @code{inputs}, but the specified packages will be
2147 force-installed alongside the package they belong to
2148 (@pxref{package-cmd-propagated-inputs, @command{guix package}}, for
2149 information on how @command{guix package} deals with propagated inputs.)
2151 For example this is necessary when a library needs headers of another
2152 library to compile, or needs another shared library to be linked
2153 alongside itself when a program wants to link to it.
2155 @item @code{native-inputs} (default: @code{'()})
2156 This field is like @code{inputs}, but in case of a cross-compilation it
2157 will be ensured that packages for the architecture of the build machine
2158 are present, such that executables from them can be used during the
2161 This is typically where you would list tools needed at build time but
2162 not at run time, such as Autoconf, Automake, pkg-config, Gettext, or
2163 Bison. @command{guix lint} can report likely mistakes in this area
2164 (@pxref{Invoking guix lint}).
2166 @item @code{self-native-input?} (default: @code{#f})
2167 This is a Boolean field telling whether the package should use itself as
2168 a native input when cross-compiling.
2170 @item @code{outputs} (default: @code{'("out")})
2171 The list of output names of the package. @xref{Packages with Multiple
2172 Outputs}, for typical uses of additional outputs.
2174 @item @code{native-search-paths} (default: @code{'()})
2175 @itemx @code{search-paths} (default: @code{'()})
2176 A list of @code{search-path-specification} objects describing
2177 search-path environment variables honored by the package.
2179 @item @code{replacement} (default: @code{#f})
2180 This must either @code{#f} or a package object that will be used as a
2181 @dfn{replacement} for this package. @xref{Security Updates, grafts},
2184 @item @code{synopsis}
2185 A one-line description of the package.
2187 @item @code{description}
2188 A more elaborate description of the package.
2190 @item @code{license}
2191 The license of the package; a value from @code{(guix licenses)}.
2193 @item @code{home-page}
2194 The URL to the home-page of the package, as a string.
2196 @item @code{supported-systems} (default: @var{%supported-systems})
2197 The list of systems supported by the package, as strings of the form
2198 @code{architecture-kernel}, for example @code{"x86_64-linux"}.
2200 @item @code{maintainers} (default: @code{'()})
2201 The list of maintainers of the package, as @code{maintainer} objects.
2203 @item @code{location} (default: source location of the @code{package} form)
2204 The source location of the package. It's useful to override this when
2205 inheriting from another package, in which case this field is not
2206 automatically corrected.
2211 @node origin Reference
2212 @subsection @code{origin} Reference
2214 This section summarizes all the options available in @code{origin}
2215 declarations (@pxref{Defining Packages}).
2217 @deftp {Data Type} origin
2218 This is the data type representing a source code origin.
2222 An object containing the URI of the source. The object type depends on
2223 the @code{method} (see below). For example, when using the
2224 @var{url-fetch} method of @code{(guix download)}, the valid @code{uri}
2225 values are: a URL represented as a string, or a list thereof.
2228 A procedure that will handle the URI.
2233 @item @var{url-fetch} from @code{(guix download)}
2234 download a file the HTTP, HTTPS, or FTP URL specified in the
2237 @item @var{git-fetch} from @code{(guix git-download)}
2238 clone the Git version control repository, and check out the revision
2239 specified in the @code{uri} field as a @code{git-reference} object; a
2240 @code{git-reference} looks like this:
2244 (url "git://git.debian.org/git/pkg-shadow/shadow")
2245 (commit "v4.1.5.1"))
2250 A bytevector containing the SHA-256 hash of the source. Typically the
2251 @code{base32} form is used here to generate the bytevector from a
2254 @item @code{file-name} (default: @code{#f})
2255 The file name under which the source code should be saved. When this is
2256 @code{#f}, a sensible default value will be used in most cases. In case
2257 the source is fetched from a URL, the file name from the URL will be
2258 used. For version control checkouts, it's recommended to provide the
2259 file name explicitly because the default is not very descriptive.
2261 @item @code{patches} (default: @code{'()})
2262 A list of file names containing patches to be applied to the source.
2264 @item @code{snippet} (default: @code{#f})
2265 A quoted piece of code that will be run in the source directory to make
2266 any modifications, which is sometimes more convenient than a patch.
2268 @item @code{patch-flags} (default: @code{'("-p1")})
2269 A list of command-line flags that should be passed to the @code{patch}
2272 @item @code{patch-inputs} (default: @code{#f})
2273 Input packages or derivations to the patching process. When this is
2274 @code{#f}, the usual set of inputs necessary for patching are provided,
2275 such as GNU@tie{}Patch.
2277 @item @code{modules} (default: @code{'()})
2278 A list of Guile modules that should be loaded during the patching
2279 process and while running the code in the @code{snippet} field.
2281 @item @code{imported-modules} (default: @code{'()})
2282 The list of Guile modules to import in the patch derivation, for use by
2285 @item @code{patch-guile} (default: @code{#f})
2286 The Guile package that should be used in the patching process. When
2287 this is @code{#f}, a sensible default is used.
2293 @section Build Systems
2295 @cindex build system
2296 Each package definition specifies a @dfn{build system} and arguments for
2297 that build system (@pxref{Defining Packages}). This @code{build-system}
2298 field represents the build procedure of the package, as well implicit
2299 dependencies of that build procedure.
2301 Build systems are @code{<build-system>} objects. The interface to
2302 create and manipulate them is provided by the @code{(guix build-system)}
2303 module, and actual build systems are exported by specific modules.
2305 @cindex bag (low-level package representation)
2306 Under the hood, build systems first compile package objects to
2307 @dfn{bags}. A @dfn{bag} is like a package, but with less
2308 ornamentation---in other words, a bag is a lower-level representation of
2309 a package, which includes all the inputs of that package, including some
2310 that were implicitly added by the build system. This intermediate
2311 representation is then compiled to a derivation (@pxref{Derivations}).
2313 Build systems accept an optional list of @dfn{arguments}. In package
2314 definitions, these are passed @i{via} the @code{arguments} field
2315 (@pxref{Defining Packages}). They are typically keyword arguments
2316 (@pxref{Optional Arguments, keyword arguments in Guile,, guile, GNU
2317 Guile Reference Manual}). The value of these arguments is usually
2318 evaluated in the @dfn{build stratum}---i.e., by a Guile process launched
2319 by the daemon (@pxref{Derivations}).
2321 The main build system is @var{gnu-build-system}, which implements the
2322 standard build procedure for GNU packages and many other packages. It
2323 is provided by the @code{(guix build-system gnu)} module.
2325 @defvr {Scheme Variable} gnu-build-system
2326 @var{gnu-build-system} represents the GNU Build System, and variants
2327 thereof (@pxref{Configuration, configuration and makefile conventions,,
2328 standards, GNU Coding Standards}).
2330 @cindex build phases
2331 In a nutshell, packages using it configured, built, and installed with
2332 the usual @code{./configure && make && make check && make install}
2333 command sequence. In practice, a few additional steps are often needed.
2334 All these steps are split up in separate @dfn{phases},
2335 notably@footnote{Please see the @code{(guix build gnu-build-system)}
2336 modules for more details about the build phases.}:
2340 Unpack the source tarball, and change the current directory to the
2341 extracted source tree. If the source is actually a directory, copy it
2342 to the build tree, and enter that directory.
2344 @item patch-source-shebangs
2345 Patch shebangs encountered in source files so they refer to the right
2346 store file names. For instance, this changes @code{#!/bin/sh} to
2347 @code{#!/gnu/store/@dots{}-bash-4.3/bin/sh}.
2350 Run the @file{configure} script with a number of default options, such
2351 as @code{--prefix=/gnu/store/@dots{}}, as well as the options specified
2352 by the @code{#:configure-flags} argument.
2355 Run @code{make} with the list of flags specified with
2356 @code{#:make-flags}. If the @code{#:parallel-builds?} argument is true
2357 (the default), build with @code{make -j}.
2360 Run @code{make check}, or some other target specified with
2361 @code{#:test-target}, unless @code{#:tests? #f} is passed. If the
2362 @code{#:parallel-tests?} argument is true (the default), run @code{make
2366 Run @code{make install} with the flags listed in @code{#:make-flags}.
2368 @item patch-shebangs
2369 Patch shebangs on the installed executable files.
2372 Strip debugging symbols from ELF files (unless @code{#:strip-binaries?}
2373 is false), copying them to the @code{debug} output when available
2374 (@pxref{Installing Debugging Files}).
2377 @vindex %standard-phases
2378 The build-side module @code{(guix build gnu-build-system)} defines
2379 @var{%standard-phases} as the default list of build phases.
2380 @var{%standard-phases} is a list of symbol/procedure pairs, where the
2381 procedure implements the actual phase.
2383 The list of phases used for a particular package can be changed with the
2384 @code{#:phases} parameter. For instance, passing:
2387 #:phases (alist-delete 'configure %standard-phases)
2390 means that all the phases described above will be used, except the
2391 @code{configure} phase.
2393 In addition, this build system ensures that the ``standard'' environment
2394 for GNU packages is available. This includes tools such as GCC, libc,
2395 Coreutils, Bash, Make, Diffutils, grep, and sed (see the @code{(guix
2396 build-system gnu)} module for a complete list.) We call these the
2397 @dfn{implicit inputs} of a package, because package definitions don't
2398 have to mention them.
2401 Other @code{<build-system>} objects are defined to support other
2402 conventions and tools used by free software packages. They inherit most
2403 of @var{gnu-build-system}, and differ mainly in the set of inputs
2404 implicitly added to the build process, and in the list of phases
2405 executed. Some of these build systems are listed below.
2407 @defvr {Scheme Variable} cmake-build-system
2408 This variable is exported by @code{(guix build-system cmake)}. It
2409 implements the build procedure for packages using the
2410 @url{http://www.cmake.org, CMake build tool}.
2412 It automatically adds the @code{cmake} package to the set of inputs.
2413 Which package is used can be specified with the @code{#:cmake}
2416 The @code{#:configure-flags} parameter is taken as a list of flags
2417 passed to the @command{cmake} command. The @code{#:build-type}
2418 parameter specifies in abstract terms the flags passed to the compiler;
2419 it defaults to @code{"RelWithDebInfo"} (short for ``release mode with
2420 debugging information''), which roughly means that code is compiled with
2421 @code{-O2 -g}, as is the case for Autoconf-based packages by default.
2424 @defvr {Scheme Variable} glib-or-gtk-build-system
2425 This variable is exported by @code{(guix build-system glib-or-gtk)}. It
2426 is intended for use with packages making use of GLib or GTK+.
2428 This build system adds the following two phases to the ones defined by
2429 @var{gnu-build-system}:
2432 @item glib-or-gtk-wrap
2433 The phase @code{glib-or-gtk-wrap} ensures that programs found under
2434 @file{bin/} are able to find GLib's ``schemas'' and
2435 @uref{https://developer.gnome.org/gtk3/stable/gtk-running.html, GTK+
2436 modules}. This is achieved by wrapping the programs in launch scripts
2437 that appropriately set the @code{XDG_DATA_DIRS} and @code{GTK_PATH}
2438 environment variables.
2440 It is possible to exclude specific package outputs from that wrapping
2441 process by listing their names in the
2442 @code{#:glib-or-gtk-wrap-excluded-outputs} parameter. This is useful
2443 when an output is known not to contain any GLib or GTK+ binaries, and
2444 where wrapping would gratuitously add a dependency of that output on
2447 @item glib-or-gtk-compile-schemas
2448 The phase @code{glib-or-gtk-compile-schemas} makes sure that all GLib's
2449 @uref{https://developer.gnome.org/gio/stable/glib-compile-schemas.html,
2450 GSettings schemas} are compiled. Compilation is performed by the
2451 @command{glib-compile-schemas} program. It is provided by the package
2452 @code{glib:bin} which is automatically imported by the build system.
2453 The @code{glib} package providing @command{glib-compile-schemas} can be
2454 specified with the @code{#:glib} parameter.
2457 Both phases are executed after the @code{install} phase.
2460 @defvr {Scheme Variable} python-build-system
2461 This variable is exported by @code{(guix build-system python)}. It
2462 implements the more or less standard build procedure used by Python
2463 packages, which consists in running @code{python setup.py build} and
2464 then @code{python setup.py install --prefix=/gnu/store/@dots{}}.
2466 For packages that install stand-alone Python programs under @code{bin/},
2467 it takes care of wrapping these programs so their @code{PYTHONPATH}
2468 environment variable points to all the Python libraries they depend on.
2470 Which Python package is used can be specified with the @code{#:python}
2474 @defvr {Scheme Variable} perl-build-system
2475 This variable is exported by @code{(guix build-system perl)}. It
2476 implements the standard build procedure for Perl packages, which either
2477 consists in running @code{perl Build.PL --prefix=/gnu/store/@dots{}},
2478 followed by @code{Build} and @code{Build install}; or in running
2479 @code{perl Makefile.PL PREFIX=/gnu/store/@dots{}}, followed by
2480 @code{make} and @code{make install}; depending on which of
2481 @code{Build.PL} or @code{Makefile.PL} is present in the package
2482 distribution. Preference is given to the former if both @code{Build.PL}
2483 and @code{Makefile.PL} exist in the package distribution. This
2484 preference can be reversed by specifying @code{#t} for the
2485 @code{#:make-maker?} parameter.
2487 The initial @code{perl Makefile.PL} or @code{perl Build.PL} invocation
2488 passes flags specified by the @code{#:make-maker-flags} or
2489 @code{#:module-build-flags} parameter, respectively.
2491 Which Perl package is used can be specified with @code{#:perl}.
2494 @defvr {Scheme Variable} ruby-build-system
2495 This variable is exported by @code{(guix build-system ruby)}. It
2496 implements the RubyGems build procedure used by Ruby packages, which
2497 involves running @code{gem build} followed by @code{gem install}.
2499 The @code{source} field of a package that uses this build system is
2500 expected to reference a gem archive instead of a traditional tarball,
2501 since this is the format that all Ruby developers use when releasing
2502 their software. The build system unpacks the gem archive, potentially
2503 patches the source, runs the test suite, repackages the gem, and
2506 Which Ruby package is used can be specified with the @code{#:ruby}
2507 parameter. A list of additional flags to be passed to the @command{gem}
2508 command can be specified with the @code{#:gem-flags} parameter.
2511 @defvr {Scheme Variable} waf-build-system
2512 This variable is exported by @code{(guix build-system waf)}. It
2513 implements a build procedure around the @code{waf} script. The common
2514 phases---@code{configure}, @code{build}, and @code{install}---are
2515 implemented by passing their names as arguments to the @code{waf}
2518 The @code{waf} script is executed by the Python interpreter. Which
2519 Python package is used to run the script can be specified with the
2520 @code{#:python} parameter.
2523 @defvr {Scheme Variable} haskell-build-system
2524 This variable is exported by @code{(guix build-system haskell)}. It
2525 implements the Cabal build procedure used by Haskell packages, which
2526 involves running @code{runhaskell Setup.hs configure
2527 --prefix=/gnu/store/@dots{}} and @code{runhaskell Setup.hs build}.
2528 Instead of installing the package by running @code{runhaskell Setup.hs
2529 install}, to avoid trying to register libraries in the read-only
2530 compiler store directory, the build system uses @code{runhaskell
2531 Setup.hs copy}, followed by @code{runhaskell Setup.hs register}. In
2532 addition, the build system generates the package documentation by
2533 running @code{runhaskell Setup.hs haddock}, unless @code{#:haddock? #f}
2534 is passed. Optional Haddock parameters can be passed with the help of
2535 the @code{#:haddock-flags} parameter. If the file @code{Setup.hs} is
2536 not found, the build system looks for @code{Setup.lhs} instead.
2538 Which Haskell compiler is used can be specified with the @code{#:haskell}
2539 parameter which defaults to @code{ghc}.
2542 @defvr {Scheme Variable} emacs-build-system
2543 This variable is exported by @code{(guix build-system emacs)}. It
2544 implements an installation procedure similar to the one of Emacs' own
2545 packaging system (@pxref{Packages,,, emacs, The GNU Emacs Manual}).
2547 It first creates the @code{@var{package}-autoloads.el} file, then it
2548 byte compiles all Emacs Lisp files. Differently from the Emacs
2549 packaging system, the Info documentation files are moved to the standard
2550 documentation directory and the @file{dir} file is deleted. Each
2551 package is installed in its own directory under
2552 @file{share/emacs/site-lisp/guix.d}.
2555 Lastly, for packages that do not need anything as sophisticated, a
2556 ``trivial'' build system is provided. It is trivial in the sense that
2557 it provides basically no support: it does not pull any implicit inputs,
2558 and does not have a notion of build phases.
2560 @defvr {Scheme Variable} trivial-build-system
2561 This variable is exported by @code{(guix build-system trivial)}.
2563 This build system requires a @code{#:builder} argument. This argument
2564 must be a Scheme expression that builds the package's output(s)---as
2565 with @code{build-expression->derivation} (@pxref{Derivations,
2566 @code{build-expression->derivation}}).
2575 Conceptually, the @dfn{store} is where derivations that have been
2576 successfully built are stored---by default, under @file{/gnu/store}.
2577 Sub-directories in the store are referred to as @dfn{store paths}. The
2578 store has an associated database that contains information such as the
2579 store paths referred to by each store path, and the list of @emph{valid}
2580 store paths---paths that result from a successful build.
2582 The store is always accessed by the daemon on behalf of its clients
2583 (@pxref{Invoking guix-daemon}). To manipulate the store, clients
2584 connect to the daemon over a Unix-domain socket, send it requests, and
2585 read the result---these are remote procedure calls, or RPCs.
2587 The @code{(guix store)} module provides procedures to connect to the
2588 daemon, and to perform RPCs. These are described below.
2590 @deffn {Scheme Procedure} open-connection [@var{file}] [#:reserve-space? #t]
2591 Connect to the daemon over the Unix-domain socket at @var{file}. When
2592 @var{reserve-space?} is true, instruct it to reserve a little bit of
2593 extra space on the file system so that the garbage collector can still
2594 operate, should the disk become full. Return a server object.
2596 @var{file} defaults to @var{%default-socket-path}, which is the normal
2597 location given the options that were passed to @command{configure}.
2600 @deffn {Scheme Procedure} close-connection @var{server}
2601 Close the connection to @var{server}.
2604 @defvr {Scheme Variable} current-build-output-port
2605 This variable is bound to a SRFI-39 parameter, which refers to the port
2606 where build and error logs sent by the daemon should be written.
2609 Procedures that make RPCs all take a server object as their first
2612 @deffn {Scheme Procedure} valid-path? @var{server} @var{path}
2613 Return @code{#t} when @var{path} is a valid store path.
2616 @deffn {Scheme Procedure} add-text-to-store @var{server} @var{name} @var{text} [@var{references}]
2617 Add @var{text} under file @var{name} in the store, and return its store
2618 path. @var{references} is the list of store paths referred to by the
2619 resulting store path.
2622 @deffn {Scheme Procedure} build-derivations @var{server} @var{derivations}
2623 Build @var{derivations} (a list of @code{<derivation>} objects or
2624 derivation paths), and return when the worker is done building them.
2625 Return @code{#t} on success.
2628 Note that the @code{(guix monads)} module provides a monad as well as
2629 monadic versions of the above procedures, with the goal of making it
2630 more convenient to work with code that accesses the store (@pxref{The
2634 @i{This section is currently incomplete.}
2637 @section Derivations
2640 Low-level build actions and the environment in which they are performed
2641 are represented by @dfn{derivations}. A derivation contain the
2642 following pieces of information:
2646 The outputs of the derivation---derivations produce at least one file or
2647 directory in the store, but may produce more.
2650 The inputs of the derivations, which may be other derivations or plain
2651 files in the store (patches, build scripts, etc.)
2654 The system type targeted by the derivation---e.g., @code{x86_64-linux}.
2657 The file name of a build script in the store, along with the arguments
2661 A list of environment variables to be defined.
2665 @cindex derivation path
2666 Derivations allow clients of the daemon to communicate build actions to
2667 the store. They exist in two forms: as an in-memory representation,
2668 both on the client- and daemon-side, and as files in the store whose
2669 name end in @code{.drv}---these files are referred to as @dfn{derivation
2670 paths}. Derivations paths can be passed to the @code{build-derivations}
2671 procedure to perform the build actions they prescribe (@pxref{The
2674 The @code{(guix derivations)} module provides a representation of
2675 derivations as Scheme objects, along with procedures to create and
2676 otherwise manipulate derivations. The lowest-level primitive to create
2677 a derivation is the @code{derivation} procedure:
2679 @deffn {Scheme Procedure} derivation @var{store} @var{name} @var{builder} @
2680 @var{args} [#:outputs '("out")] [#:hash #f] [#:hash-algo #f] @
2681 [#:recursive? #f] [#:inputs '()] [#:env-vars '()] @
2682 [#:system (%current-system)] [#:references-graphs #f] @
2683 [#:allowed-references #f] [#:leaked-env-vars #f] [#:local-build? #f] @
2684 [#:substitutable? #t]
2685 Build a derivation with the given arguments, and return the resulting
2686 @code{<derivation>} object.
2688 When @var{hash} and @var{hash-algo} are given, a
2689 @dfn{fixed-output derivation} is created---i.e., one whose result is
2690 known in advance, such as a file download. If, in addition,
2691 @var{recursive?} is true, then that fixed output may be an executable
2692 file or a directory and @var{hash} must be the hash of an archive
2693 containing this output.
2695 When @var{references-graphs} is true, it must be a list of file
2696 name/store path pairs. In that case, the reference graph of each store
2697 path is exported in the build environment in the corresponding file, in
2698 a simple text format.
2700 When @var{allowed-references} is true, it must be a list of store items
2701 or outputs that the derivation's output may refer to.
2703 When @var{leaked-env-vars} is true, it must be a list of strings
2704 denoting environment variables that are allowed to ``leak'' from the
2705 daemon's environment to the build environment. This is only applicable
2706 to fixed-output derivations---i.e., when @var{hash} is true. The main
2707 use is to allow variables such as @code{http_proxy} to be passed to
2708 derivations that download files.
2710 When @var{local-build?} is true, declare that the derivation is not a
2711 good candidate for offloading and should rather be built locally
2712 (@pxref{Daemon Offload Setup}). This is the case for small derivations
2713 where the costs of data transfers would outweigh the benefits.
2715 When @var{substitutable?} is false, declare that substitutes of the
2716 derivation's output should not be used (@pxref{Substitutes}). This is
2717 useful, for instance, when building packages that capture details of the
2718 host CPU instruction set.
2722 Here's an example with a shell script as its builder, assuming
2723 @var{store} is an open connection to the daemon, and @var{bash} points
2724 to a Bash executable in the store:
2727 (use-modules (guix utils)
2731 (let ((builder ; add the Bash script to the store
2732 (add-text-to-store store "my-builder.sh"
2733 "echo hello world > $out\n" '())))
2734 (derivation store "foo"
2735 bash `("-e" ,builder)
2736 #:inputs `((,bash) (,builder))
2737 #:env-vars '(("HOME" . "/homeless"))))
2738 @result{} #<derivation /gnu/store/@dots{}-foo.drv => /gnu/store/@dots{}-foo>
2741 As can be guessed, this primitive is cumbersome to use directly. A
2742 better approach is to write build scripts in Scheme, of course! The
2743 best course of action for that is to write the build code as a
2744 ``G-expression'', and to pass it to @code{gexp->derivation}. For more
2745 information, @pxref{G-Expressions}.
2747 Once upon a time, @code{gexp->derivation} did not exist and constructing
2748 derivations with build code written in Scheme was achieved with
2749 @code{build-expression->derivation}, documented below. This procedure
2750 is now deprecated in favor of the much nicer @code{gexp->derivation}.
2752 @deffn {Scheme Procedure} build-expression->derivation @var{store} @
2753 @var{name} @var{exp} @
2754 [#:system (%current-system)] [#:inputs '()] @
2755 [#:outputs '("out")] [#:hash #f] [#:hash-algo #f] @
2756 [#:recursive? #f] [#:env-vars '()] [#:modules '()] @
2757 [#:references-graphs #f] [#:allowed-references #f] @
2758 [#:local-build? #f] [#:substitutable? #t] [#:guile-for-build #f]
2759 Return a derivation that executes Scheme expression @var{exp} as a
2760 builder for derivation @var{name}. @var{inputs} must be a list of
2761 @code{(name drv-path sub-drv)} tuples; when @var{sub-drv} is omitted,
2762 @code{"out"} is assumed. @var{modules} is a list of names of Guile
2763 modules from the current search path to be copied in the store,
2764 compiled, and made available in the load path during the execution of
2765 @var{exp}---e.g., @code{((guix build utils) (guix build
2766 gnu-build-system))}.
2768 @var{exp} is evaluated in an environment where @code{%outputs} is bound
2769 to a list of output/path pairs, and where @code{%build-inputs} is bound
2770 to a list of string/output-path pairs made from @var{inputs}.
2771 Optionally, @var{env-vars} is a list of string pairs specifying the name
2772 and value of environment variables visible to the builder. The builder
2773 terminates by passing the result of @var{exp} to @code{exit}; thus, when
2774 @var{exp} returns @code{#f}, the build is considered to have failed.
2776 @var{exp} is built using @var{guile-for-build} (a derivation). When
2777 @var{guile-for-build} is omitted or is @code{#f}, the value of the
2778 @code{%guile-for-build} fluid is used instead.
2780 See the @code{derivation} procedure for the meaning of
2781 @var{references-graphs}, @var{allowed-references}, @var{local-build?},
2782 and @var{substitutable?}.
2786 Here's an example of a single-output derivation that creates a directory
2787 containing one file:
2790 (let ((builder '(let ((out (assoc-ref %outputs "out")))
2791 (mkdir out) ; create /gnu/store/@dots{}-goo
2792 (call-with-output-file (string-append out "/test")
2794 (display '(hello guix) p))))))
2795 (build-expression->derivation store "goo" builder))
2797 @result{} #<derivation /gnu/store/@dots{}-goo.drv => @dots{}>
2801 @node The Store Monad
2802 @section The Store Monad
2806 The procedures that operate on the store described in the previous
2807 sections all take an open connection to the build daemon as their first
2808 argument. Although the underlying model is functional, they either have
2809 side effects or depend on the current state of the store.
2811 The former is inconvenient: the connection to the build daemon has to be
2812 carried around in all those functions, making it impossible to compose
2813 functions that do not take that parameter with functions that do. The
2814 latter can be problematic: since store operations have side effects
2815 and/or depend on external state, they have to be properly sequenced.
2817 @cindex monadic values
2818 @cindex monadic functions
2819 This is where the @code{(guix monads)} module comes in. This module
2820 provides a framework for working with @dfn{monads}, and a particularly
2821 useful monad for our uses, the @dfn{store monad}. Monads are a
2822 construct that allows two things: associating ``context'' with values
2823 (in our case, the context is the store), and building sequences of
2824 computations (here computations include accesses to the store.) Values
2825 in a monad---values that carry this additional context---are called
2826 @dfn{monadic values}; procedures that return such values are called
2827 @dfn{monadic procedures}.
2829 Consider this ``normal'' procedure:
2832 (define (sh-symlink store)
2833 ;; Return a derivation that symlinks the 'bash' executable.
2834 (let* ((drv (package-derivation store bash))
2835 (out (derivation->output-path drv))
2836 (sh (string-append out "/bin/bash")))
2837 (build-expression->derivation store "sh"
2838 `(symlink ,sh %output))))
2841 Using @code{(guix monads)} and @code{(guix gexp)}, it may be rewritten
2842 as a monadic function:
2845 (define (sh-symlink)
2846 ;; Same, but return a monadic value.
2847 (mlet %store-monad ((drv (package->derivation bash)))
2848 (gexp->derivation "sh"
2849 #~(symlink (string-append #$drv "/bin/bash")
2853 There several things to note in the second version: the @code{store}
2854 parameter is now implicit and is ``threaded'' in the calls to the
2855 @code{package->derivation} and @code{gexp->derivation} monadic
2856 procedures, and the monadic value returned by @code{package->derivation}
2857 is @dfn{bound} using @code{mlet} instead of plain @code{let}.
2859 As it turns out, the call to @code{package->derivation} can even be
2860 omitted since it will take place implicitly, as we will see later
2861 (@pxref{G-Expressions}):
2864 (define (sh-symlink)
2865 (gexp->derivation "sh"
2866 #~(symlink (string-append #$bash "/bin/bash")
2871 @c <https://syntaxexclamation.wordpress.com/2014/06/26/escaping-continuations/>
2872 @c for the funny quote.
2873 Calling the monadic @code{sh-symlink} has no effect. As someone once
2874 said, ``you exit a monad like you exit a building on fire: by running''.
2875 So, to exit the monad and get the desired effect, one must use
2876 @code{run-with-store}:
2879 (run-with-store (open-connection) (sh-symlink))
2880 @result{} /gnu/store/...-sh-symlink
2883 Note that the @code{(guix monad-repl)} module extends Guile's REPL with
2884 new ``meta-commands'' to make it easier to deal with monadic procedures:
2885 @code{run-in-store}, and @code{enter-store-monad}. The former, is used
2886 to ``run'' a single monadic value through the store:
2889 scheme@@(guile-user)> ,run-in-store (package->derivation hello)
2890 $1 = #<derivation /gnu/store/@dots{}-hello-2.9.drv => @dots{}>
2893 The latter enters a recursive REPL, where all the return values are
2894 automatically run through the store:
2897 scheme@@(guile-user)> ,enter-store-monad
2898 store-monad@@(guile-user) [1]> (package->derivation hello)
2899 $2 = #<derivation /gnu/store/@dots{}-hello-2.9.drv => @dots{}>
2900 store-monad@@(guile-user) [1]> (text-file "foo" "Hello!")
2901 $3 = "/gnu/store/@dots{}-foo"
2902 store-monad@@(guile-user) [1]> ,q
2903 scheme@@(guile-user)>
2907 Note that non-monadic values cannot be returned in the
2908 @code{store-monad} REPL.
2910 The main syntactic forms to deal with monads in general are provided by
2911 the @code{(guix monads)} module and are described below.
2913 @deffn {Scheme Syntax} with-monad @var{monad} @var{body} ...
2914 Evaluate any @code{>>=} or @code{return} forms in @var{body} as being
2918 @deffn {Scheme Syntax} return @var{val}
2919 Return a monadic value that encapsulates @var{val}.
2922 @deffn {Scheme Syntax} >>= @var{mval} @var{mproc} ...
2923 @dfn{Bind} monadic value @var{mval}, passing its ``contents'' to monadic
2924 procedures @var{mproc}@dots{}@footnote{This operation is commonly
2925 referred to as ``bind'', but that name denotes an unrelated procedure in
2926 Guile. Thus we use this somewhat cryptic symbol inherited from the
2927 Haskell language.}. There can be one @var{mproc} or several of them, as
2932 (with-monad %state-monad
2934 (lambda (x) (return (+ 1 x)))
2935 (lambda (x) (return (* 2 x)))))
2939 @result{} some-state
2943 @deffn {Scheme Syntax} mlet @var{monad} ((@var{var} @var{mval}) ...) @
2945 @deffnx {Scheme Syntax} mlet* @var{monad} ((@var{var} @var{mval}) ...) @
2947 Bind the variables @var{var} to the monadic values @var{mval} in
2948 @var{body}. The form (@var{var} -> @var{val}) binds @var{var} to the
2949 ``normal'' value @var{val}, as per @code{let}.
2951 @code{mlet*} is to @code{mlet} what @code{let*} is to @code{let}
2952 (@pxref{Local Bindings,,, guile, GNU Guile Reference Manual}).
2955 @deffn {Scheme System} mbegin @var{monad} @var{mexp} ...
2956 Bind @var{mexp} and the following monadic expressions in sequence,
2957 returning the result of the last expression.
2959 This is akin to @code{mlet}, except that the return values of the
2960 monadic expressions are ignored. In that sense, it is analogous to
2961 @code{begin}, but applied to monadic expressions.
2965 The @code{(guix monads)} module provides the @dfn{state monad}, which
2966 allows an additional value---the state---to be @emph{threaded} through
2967 monadic procedure calls.
2969 @defvr {Scheme Variable} %state-monad
2970 The state monad. Procedures in the state monad can access and change
2971 the state that is threaded.
2973 Consider the example below. The @code{square} procedure returns a value
2974 in the state monad. It returns the square of its argument, but also
2975 increments the current state value:
2979 (mlet %state-monad ((count (current-state)))
2980 (mbegin %state-monad
2981 (set-current-state (+ 1 count))
2984 (run-with-state (sequence %state-monad (map square (iota 3))) 0)
2989 When ``run'' through @var{%state-monad}, we obtain that additional state
2990 value, which is the number of @code{square} calls.
2993 @deffn {Monadic Procedure} current-state
2994 Return the current state as a monadic value.
2997 @deffn {Monadic Procedure} set-current-state @var{value}
2998 Set the current state to @var{value} and return the previous state as a
3002 @deffn {Monadic Procedure} state-push @var{value}
3003 Push @var{value} to the current state, which is assumed to be a list,
3004 and return the previous state as a monadic value.
3007 @deffn {Monadic Procedure} state-pop
3008 Pop a value from the current state and return it as a monadic value.
3009 The state is assumed to be a list.
3012 @deffn {Scheme Procedure} run-with-state @var{mval} [@var{state}]
3013 Run monadic value @var{mval} starting with @var{state} as the initial
3014 state. Return two values: the resulting value, and the resulting state.
3017 The main interface to the store monad, provided by the @code{(guix
3018 store)} module, is as follows.
3020 @defvr {Scheme Variable} %store-monad
3021 The store monad---an alias for @var{%state-monad}.
3023 Values in the store monad encapsulate accesses to the store. When its
3024 effect is needed, a value of the store monad must be ``evaluated'' by
3025 passing it to the @code{run-with-store} procedure (see below.)
3028 @deffn {Scheme Procedure} run-with-store @var{store} @var{mval} [#:guile-for-build] [#:system (%current-system)]
3029 Run @var{mval}, a monadic value in the store monad, in @var{store}, an
3030 open store connection.
3033 @deffn {Monadic Procedure} text-file @var{name} @var{text} [@var{references}]
3034 Return as a monadic value the absolute file name in the store of the file
3035 containing @var{text}, a string. @var{references} is a list of store items that the
3036 resulting text file refers to; it defaults to the empty list.
3039 @deffn {Monadic Procedure} interned-file @var{file} [@var{name}] @
3041 Return the name of @var{file} once interned in the store. Use
3042 @var{name} as its store name, or the basename of @var{file} if
3043 @var{name} is omitted.
3045 When @var{recursive?} is true, the contents of @var{file} are added
3046 recursively; if @var{file} designates a flat file and @var{recursive?}
3047 is true, its contents are added, and its permission bits are kept.
3049 The example below adds a file to the store, under two different names:
3052 (run-with-store (open-connection)
3053 (mlet %store-monad ((a (interned-file "README"))
3054 (b (interned-file "README" "LEGU-MIN")))
3055 (return (list a b))))
3057 @result{} ("/gnu/store/rwm@dots{}-README" "/gnu/store/44i@dots{}-LEGU-MIN")
3062 The @code{(guix packages)} module exports the following package-related
3065 @deffn {Monadic Procedure} package-file @var{package} [@var{file}] @
3066 [#:system (%current-system)] [#:target #f] @
3067 [#:output "out"] Return as a monadic
3068 value in the absolute file name of @var{file} within the @var{output}
3069 directory of @var{package}. When @var{file} is omitted, return the name
3070 of the @var{output} directory of @var{package}. When @var{target} is
3071 true, use it as a cross-compilation target triplet.
3074 @deffn {Monadic Procedure} package->derivation @var{package} [@var{system}]
3075 @deffnx {Monadic Procedure} package->cross-derivation @var{package} @
3076 @var{target} [@var{system}]
3077 Monadic version of @code{package-derivation} and
3078 @code{package-cross-derivation} (@pxref{Defining Packages}).
3083 @section G-Expressions
3085 @cindex G-expression
3086 @cindex build code quoting
3087 So we have ``derivations'', which represent a sequence of build actions
3088 to be performed to produce an item in the store (@pxref{Derivations}).
3089 Those build actions are performed when asking the daemon to actually
3090 build the derivations; they are run by the daemon in a container
3091 (@pxref{Invoking guix-daemon}).
3093 @cindex strata of code
3094 It should come as no surprise that we like to write those build actions
3095 in Scheme. When we do that, we end up with two @dfn{strata} of Scheme
3096 code@footnote{The term @dfn{stratum} in this context was coined by
3097 Manuel Serrano et al.@: in the context of their work on Hop. Oleg
3098 Kiselyov, who has written insightful
3099 @url{http://okmij.org/ftp/meta-programming/#meta-scheme, essays and code
3100 on this topic}, refers to this kind of code generation as
3101 @dfn{staging}.}: the ``host code''---code that defines packages, talks
3102 to the daemon, etc.---and the ``build code''---code that actually
3103 performs build actions, such as making directories, invoking
3104 @command{make}, etc.
3106 To describe a derivation and its build actions, one typically needs to
3107 embed build code inside host code. It boils down to manipulating build
3108 code as data, and Scheme's homoiconicity---code has a direct
3109 representation as data---comes in handy for that. But we need more than
3110 Scheme's normal @code{quasiquote} mechanism to construct build
3113 The @code{(guix gexp)} module implements @dfn{G-expressions}, a form of
3114 S-expressions adapted to build expressions. G-expressions, or
3115 @dfn{gexps}, consist essentially in three syntactic forms: @code{gexp},
3116 @code{ungexp}, and @code{ungexp-splicing} (or simply: @code{#~},
3117 @code{#$}, and @code{#$@@}), which are comparable respectively to
3118 @code{quasiquote}, @code{unquote}, and @code{unquote-splicing}
3119 (@pxref{Expression Syntax, @code{quasiquote},, guile, GNU Guile
3120 Reference Manual}). However, there are major differences:
3124 Gexps are meant to be written to a file and run or manipulated by other
3128 When a high-level object such as a package or derivation is unquoted
3129 inside a gexp, the result is as if its output file name had been
3133 Gexps carry information about the packages or derivations they refer to,
3134 and these dependencies are automatically added as inputs to the build
3135 processes that use them.
3138 @cindex lowering, of high-level objects in gexps
3139 This mechanism is not limited to package and derivation
3140 objects: @dfn{compilers} able to ``lower'' other high-level objects to
3141 derivations or files in the store can be defined,
3142 such that these objects can also be inserted
3143 into gexps. For example, a useful type of high-level object that can be
3144 inserted in a gexp is ``file-like objects'', which make it easy to
3145 add files to the store and refer to them in
3146 derivations and such (see @code{local-file} and @code{plain-file}
3149 To illustrate the idea, here is an example of a gexp:
3156 (symlink (string-append #$coreutils "/bin/ls")
3160 This gexp can be passed to @code{gexp->derivation}; we obtain a
3161 derivation that builds a directory containing exactly one symlink to
3162 @file{/gnu/store/@dots{}-coreutils-8.22/bin/ls}:
3165 (gexp->derivation "the-thing" build-exp)
3168 As one would expect, the @code{"/gnu/store/@dots{}-coreutils-8.22"} string is
3169 substituted to the reference to the @var{coreutils} package in the
3170 actual build code, and @var{coreutils} is automatically made an input to
3171 the derivation. Likewise, @code{#$output} (equivalent to @code{(ungexp
3172 output)}) is replaced by a string containing the derivation's output
3175 @cindex cross compilation
3176 In a cross-compilation context, it is useful to distinguish between
3177 references to the @emph{native} build of a package---that can run on the
3178 host---versus references to cross builds of a package. To that end, the
3179 @code{#+} plays the same role as @code{#$}, but is a reference to a
3180 native package build:
3183 (gexp->derivation "vi"
3186 (system* (string-append #+coreutils "/bin/ln")
3188 (string-append #$emacs "/bin/emacs")
3189 (string-append #$output "/bin/vi")))
3190 #:target "mips64el-linux")
3194 In the example above, the native build of @var{coreutils} is used, so
3195 that @command{ln} can actually run on the host; but then the
3196 cross-compiled build of @var{emacs} is referenced.
3198 The syntactic form to construct gexps is summarized below.
3200 @deffn {Scheme Syntax} #~@var{exp}
3201 @deffnx {Scheme Syntax} (gexp @var{exp})
3202 Return a G-expression containing @var{exp}. @var{exp} may contain one
3203 or more of the following forms:
3207 @itemx (ungexp @var{obj})
3208 Introduce a reference to @var{obj}. @var{obj} may have one of the
3209 supported types, for example a package or a
3210 derivation, in which case the @code{ungexp} form is replaced by its
3211 output file name---e.g., @code{"/gnu/store/@dots{}-coreutils-8.22}.
3213 If @var{obj} is a list, it is traversed and references to supported
3214 objects are substituted similarly.
3216 If @var{obj} is another gexp, its contents are inserted and its
3217 dependencies are added to those of the containing gexp.
3219 If @var{obj} is another kind of object, it is inserted as is.
3221 @item #$@var{obj}:@var{output}
3222 @itemx (ungexp @var{obj} @var{output})
3223 This is like the form above, but referring explicitly to the
3224 @var{output} of @var{obj}---this is useful when @var{obj} produces
3225 multiple outputs (@pxref{Packages with Multiple Outputs}).
3228 @itemx #+@var{obj}:output
3229 @itemx (ungexp-native @var{obj})
3230 @itemx (ungexp-native @var{obj} @var{output})
3231 Same as @code{ungexp}, but produces a reference to the @emph{native}
3232 build of @var{obj} when used in a cross compilation context.
3234 @item #$output[:@var{output}]
3235 @itemx (ungexp output [@var{output}])
3236 Insert a reference to derivation output @var{output}, or to the main
3237 output when @var{output} is omitted.
3239 This only makes sense for gexps passed to @code{gexp->derivation}.
3242 @itemx (ungexp-splicing @var{lst})
3243 Like the above, but splices the contents of @var{lst} inside the
3247 @itemx (ungexp-native-splicing @var{lst})
3248 Like the above, but refers to native builds of the objects listed in
3253 G-expressions created by @code{gexp} or @code{#~} are run-time objects
3254 of the @code{gexp?} type (see below.)
3257 @deffn {Scheme Procedure} gexp? @var{obj}
3258 Return @code{#t} if @var{obj} is a G-expression.
3261 G-expressions are meant to be written to disk, either as code building
3262 some derivation, or as plain files in the store. The monadic procedures
3263 below allow you to do that (@pxref{The Store Monad}, for more
3264 information about monads.)
3266 @deffn {Monadic Procedure} gexp->derivation @var{name} @var{exp} @
3267 [#:system (%current-system)] [#:target #f] [#:graft? #t] @
3268 [#:hash #f] [#:hash-algo #f] @
3269 [#:recursive? #f] [#:env-vars '()] [#:modules '()] @
3270 [#:module-path @var{%load-path}] @
3271 [#:references-graphs #f] [#:allowed-references #f] @
3272 [#:leaked-env-vars #f] @
3273 [#:script-name (string-append @var{name} "-builder")] @
3274 [#:local-build? #f] [#:substitutable? #t] [#:guile-for-build #f]
3275 Return a derivation @var{name} that runs @var{exp} (a gexp) with
3276 @var{guile-for-build} (a derivation) on @var{system}; @var{exp} is
3277 stored in a file called @var{script-name}. When @var{target} is true,
3278 it is used as the cross-compilation target triplet for packages referred
3281 Make @var{modules} available in the evaluation context of @var{exp};
3282 @var{modules} is a list of names of Guile modules searched in
3283 @var{module-path} to be copied in the store, compiled, and made available in
3284 the load path during the execution of @var{exp}---e.g., @code{((guix
3285 build utils) (guix build gnu-build-system))}.
3287 @var{graft?} determines whether packages referred to by @var{exp} should be grafted when
3290 When @var{references-graphs} is true, it must be a list of tuples of one of the
3294 (@var{file-name} @var{package})
3295 (@var{file-name} @var{package} @var{output})
3296 (@var{file-name} @var{derivation})
3297 (@var{file-name} @var{derivation} @var{output})
3298 (@var{file-name} @var{store-item})
3301 The right-hand-side of each element of @var{references-graphs} is automatically made
3302 an input of the build process of @var{exp}. In the build environment, each
3303 @var{file-name} contains the reference graph of the corresponding item, in a simple
3306 @var{allowed-references} must be either @code{#f} or a list of output names and packages.
3307 In the latter case, the list denotes store items that the result is allowed to
3308 refer to. Any reference to another store item will lead to a build error.
3310 The other arguments are as for @code{derivation} (@pxref{Derivations}).
3313 @cindex file-like objects
3314 The @code{local-file} and @code{plain-file} procedures below return
3315 @dfn{file-like objects}. That is, when unquoted in a G-expression,
3316 these objects lead to a file in the store. Consider this G-expression:
3319 #~(system* (string-append #$glibc "/sbin/nscd") "-f"
3320 #$(local-file "/tmp/my-nscd.conf"))
3323 The effect here is to ``intern'' @file{/tmp/my-nscd.conf} by copying it
3324 to the store. Once expanded, for instance @i{via}
3325 @code{gexp->derivation}, the G-expression refers to that copy under
3326 @file{/gnu/store}; thus, modifying or removing the file in @file{/tmp}
3327 does not have any effect on what the G-expression does.
3328 @code{plain-file} can be used similarly; it differs in that the file
3329 content is directly passed as a string.
3331 @deffn {Scheme Procedure} local-file @var{file} [@var{name}] @
3333 Return an object representing local file @var{file} to add to the store; this
3334 object can be used in a gexp. @var{file} will be added to the store under @var{name}--by
3335 default the base name of @var{file}.
3337 When @var{recursive?} is true, the contents of @var{file} are added recursively; if @var{file}
3338 designates a flat file and @var{recursive?} is true, its contents are added, and its
3339 permission bits are kept.
3341 This is the declarative counterpart of the @code{interned-file} monadic
3342 procedure (@pxref{The Store Monad, @code{interned-file}}).
3345 @deffn {Scheme Procedure} plain-file @var{name} @var{content}
3346 Return an object representing a text file called @var{name} with the given
3347 @var{content} (a string) to be added to the store.
3349 This is the declarative counterpart of @code{text-file}.
3352 @deffn {Monadic Procedure} gexp->script @var{name} @var{exp}
3353 Return an executable script @var{name} that runs @var{exp} using
3354 @var{guile} with @var{modules} in its search path.
3356 The example below builds a script that simply invokes the @command{ls}
3360 (use-modules (guix gexp) (gnu packages base))
3362 (gexp->script "list-files"
3363 #~(execl (string-append #$coreutils "/bin/ls")
3367 When ``running'' it through the store (@pxref{The Store Monad,
3368 @code{run-with-store}}), we obtain a derivation that produces an
3369 executable file @file{/gnu/store/@dots{}-list-files} along these lines:
3372 #!/gnu/store/@dots{}-guile-2.0.11/bin/guile -ds
3374 (execl (string-append "/gnu/store/@dots{}-coreutils-8.22"/bin/ls")
3379 @deffn {Monadic Procedure} gexp->file @var{name} @var{exp}
3380 Return a derivation that builds a file @var{name} containing @var{exp}.
3382 The resulting file holds references to all the dependencies of @var{exp}
3383 or a subset thereof.
3386 @deffn {Monadic Procedure} text-file* @var{name} @var{text} @dots{}
3387 Return as a monadic value a derivation that builds a text file
3388 containing all of @var{text}. @var{text} may list, in addition to
3389 strings, objects of any type that can be used in a gexp: packages,
3390 derivations, local file objects, etc. The resulting store file holds
3391 references to all these.
3393 This variant should be preferred over @code{text-file} anytime the file
3394 to create will reference items from the store. This is typically the
3395 case when building a configuration file that embeds store file names,
3399 (define (profile.sh)
3400 ;; Return the name of a shell script in the store that
3401 ;; initializes the 'PATH' environment variable.
3402 (text-file* "profile.sh"
3403 "export PATH=" coreutils "/bin:"
3404 grep "/bin:" sed "/bin\n"))
3407 In this example, the resulting @file{/gnu/store/@dots{}-profile.sh} file
3408 will references @var{coreutils}, @var{grep}, and @var{sed}, thereby
3409 preventing them from being garbage-collected during its lifetime.
3412 Of course, in addition to gexps embedded in ``host'' code, there are
3413 also modules containing build tools. To make it clear that they are
3414 meant to be used in the build stratum, these modules are kept in the
3415 @code{(guix build @dots{})} name space.
3417 @cindex lowering, of high-level objects in gexps
3418 Internally, high-level objects are @dfn{lowered}, using their compiler,
3419 to either derivations or store items. For instance, lowering a package
3420 yields a derivation, and lowering a @code{plain-file} yields a store
3421 item. This is achieved using the @code{lower-object} monadic procedure.
3423 @deffn {Monadic Procedure} lower-object @var{obj} [@var{system}] @
3425 Return as a value in @var{%store-monad} the derivation or store item
3426 corresponding to @var{obj} for @var{system}, cross-compiling for
3427 @var{target} if @var{target} is true. @var{obj} must be an object that
3428 has an associated gexp compiler, such as a @code{<package>}.
3432 @c *********************************************************************
3436 This section describes tools primarily targeted at developers and users
3437 who write new package definitions. They complement the Scheme
3438 programming interface of Guix in a convenient way.
3441 * Invoking guix build:: Building packages from the command line.
3442 * Invoking guix edit:: Editing package definitions.
3443 * Invoking guix download:: Downloading a file and printing its hash.
3444 * Invoking guix hash:: Computing the cryptographic hash of a file.
3445 * Invoking guix import:: Importing package definitions.
3446 * Invoking guix refresh:: Updating package definitions.
3447 * Invoking guix lint:: Finding errors in package definitions.
3448 * Invoking guix size:: Profiling disk usage.
3449 * Invoking guix graph:: Visualizing the graph of packages.
3450 * Invoking guix environment:: Setting up development environments.
3451 * Invoking guix publish:: Sharing substitutes.
3454 @node Invoking guix build
3455 @section Invoking @command{guix build}
3457 The @command{guix build} command builds packages or derivations and
3458 their dependencies, and prints the resulting store paths. Note that it
3459 does not modify the user's profile---this is the job of the
3460 @command{guix package} command (@pxref{Invoking guix package}). Thus,
3461 it is mainly useful for distribution developers.
3463 The general syntax is:
3466 guix build @var{options} @var{package-or-derivation}@dots{}
3469 @var{package-or-derivation} may be either the name of a package found in
3470 the software distribution such as @code{coreutils} or
3471 @code{coreutils-8.20}, or a derivation such as
3472 @file{/gnu/store/@dots{}-coreutils-8.19.drv}. In the former case, a
3473 package with the corresponding name (and optionally version) is searched
3474 for among the GNU distribution modules (@pxref{Package Modules}).
3476 Alternatively, the @code{--expression} option may be used to specify a
3477 Scheme expression that evaluates to a package; this is useful when
3478 disambiguation among several same-named packages or package variants is
3481 The @var{options} may be zero or more of the following:
3485 @item --expression=@var{expr}
3486 @itemx -e @var{expr}
3487 Build the package or derivation @var{expr} evaluates to.
3489 For example, @var{expr} may be @code{(@@ (gnu packages guile)
3490 guile-1.8)}, which unambiguously designates this specific variant of
3491 version 1.8 of Guile.
3493 Alternately, @var{expr} may be a G-expression, in which case it is used
3494 as a build program passed to @code{gexp->derivation}
3495 (@pxref{G-Expressions}).
3497 Lastly, @var{expr} may refer to a zero-argument monadic procedure
3498 (@pxref{The Store Monad}). The procedure must return a derivation as a
3499 monadic value, which is then passed through @code{run-with-store}.
3503 Build the packages' source derivations, rather than the packages
3506 For instance, @code{guix build -S gcc} returns something like
3507 @file{/gnu/store/@dots{}-gcc-4.7.2.tar.bz2}, which is GCC's source tarball.
3509 The returned source tarball is the result of applying any patches and
3510 code snippets specified in the package's @code{origin} (@pxref{Defining
3514 Fetch and return the source of @var{package-or-derivation} and all their
3515 dependencies, recursively. This is a handy way to obtain a local copy
3516 of all the source code needed to build @var{packages}, allowing you to
3517 eventually build them even without network access. It is an extension
3518 of the @code{--source} option and can accept one of the following
3519 optional argument values:
3523 This value causes the @code{--sources} option to behave in the same way
3524 as the @code{--source} option.
3527 Build all packages' source derivations, including any source that might
3528 be listed as @code{inputs}. This is the default value.
3531 $ guix build --sources tzdata
3532 The following derivations will be built:
3533 /gnu/store/@dots{}-tzdata2015b.tar.gz.drv
3534 /gnu/store/@dots{}-tzcode2015b.tar.gz.drv
3538 Build all packages' source derivations, as well as all source
3539 derivations for packages' transitive inputs. This can be used e.g. to
3540 prefetch package source for later offline building.
3543 $ guix build --sources=transitive tzdata
3544 The following derivations will be built:
3545 /gnu/store/@dots{}-tzcode2015b.tar.gz.drv
3546 /gnu/store/@dots{}-findutils-4.4.2.tar.xz.drv
3547 /gnu/store/@dots{}-grep-2.21.tar.xz.drv
3548 /gnu/store/@dots{}-coreutils-8.23.tar.xz.drv
3549 /gnu/store/@dots{}-make-4.1.tar.xz.drv
3550 /gnu/store/@dots{}-bash-4.3.tar.xz.drv
3556 @item --system=@var{system}
3557 @itemx -s @var{system}
3558 Attempt to build for @var{system}---e.g., @code{i686-linux}---instead of
3559 the host's system type.
3561 An example use of this is on Linux-based systems, which can emulate
3562 different personalities. For instance, passing
3563 @code{--system=i686-linux} on an @code{x86_64-linux} system allows users
3564 to build packages in a complete 32-bit environment.
3566 @item --target=@var{triplet}
3567 @cindex cross-compilation
3568 Cross-build for @var{triplet}, which must be a valid GNU triplet, such
3569 as @code{"mips64el-linux-gnu"} (@pxref{Configuration Names, GNU
3570 configuration triplets,, configure, GNU Configure and Build System}).
3572 @item --with-source=@var{source}
3573 Use @var{source} as the source of the corresponding package.
3574 @var{source} must be a file name or a URL, as for @command{guix
3575 download} (@pxref{Invoking guix download}).
3577 The ``corresponding package'' is taken to be one specified on the
3578 command line whose name matches the base of @var{source}---e.g., if
3579 @var{source} is @code{/src/guile-2.0.10.tar.gz}, the corresponding
3580 package is @code{guile}. Likewise, the version string is inferred from
3581 @var{source}; in the previous example, it's @code{2.0.10}.
3583 This option allows users to try out versions of packages other than the
3584 one provided by the distribution. The example below downloads
3585 @file{ed-1.7.tar.gz} from a GNU mirror and uses that as the source for
3586 the @code{ed} package:
3589 guix build ed --with-source=mirror://gnu/ed/ed-1.7.tar.gz
3592 As a developer, @code{--with-source} makes it easy to test release
3596 guix build guile --with-source=../guile-2.0.9.219-e1bb7.tar.xz
3599 @dots{} or to build from a checkout in a pristine environment:
3602 $ git clone git://git.sv.gnu.org/guix.git
3603 $ guix build guix --with-source=./guix
3607 Do not ``graft'' packages. In practice, this means that package updates
3608 available as grafts are not applied. @xref{Security Updates}, for more
3609 information on grafts.
3613 Return the derivation paths, not the output paths, of the given
3616 @item --root=@var{file}
3617 @itemx -r @var{file}
3618 Make @var{file} a symlink to the result, and register it as a garbage
3622 Return the build log file names for the given
3623 @var{package-or-derivation}s, or raise an error if build logs are
3626 This works regardless of how packages or derivations are specified. For
3627 instance, the following invocations are equivalent:
3630 guix build --log-file `guix build -d guile`
3631 guix build --log-file `guix build guile`
3632 guix build --log-file guile
3633 guix build --log-file -e '(@@ (gnu packages guile) guile-2.0)'
3639 @cindex common build options
3640 In addition, a number of options that control the build process are
3641 common to @command{guix build} and other commands that can spawn builds,
3642 such as @command{guix package} or @command{guix archive}. These are the
3647 @item --load-path=@var{directory}
3648 @itemx -L @var{directory}
3649 Add @var{directory} to the front of the package module search path
3650 (@pxref{Package Modules}).
3652 This allows users to define their own packages and make them visible to
3653 the command-line tools.
3657 Keep the build tree of failed builds. Thus, if a build fail, its build
3658 tree is kept under @file{/tmp}, in a directory whose name is shown at
3659 the end of the build log. This is useful when debugging build issues.
3663 Do not build the derivations.
3666 When substituting a pre-built binary fails, fall back to building
3669 @item --substitute-urls=@var{urls}
3670 @anchor{client-substitute-urls}
3671 Consider @var{urls} the whitespace-separated list of substitute source
3672 URLs, overriding the default list of URLs of @command{guix-daemon}
3673 (@pxref{daemon-substitute-urls,, @command{guix-daemon} URLs}).
3675 This means that substitutes may be downloaded from @var{urls}, provided
3676 they are signed by a key authorized by the system administrator
3677 (@pxref{Substitutes}).
3679 @item --no-substitutes
3680 Do not use substitutes for build products. That is, always build things
3681 locally instead of allowing downloads of pre-built binaries
3682 (@pxref{Substitutes}).
3684 @item --no-build-hook
3685 Do not attempt to offload builds @i{via} the daemon's ``build hook''
3686 (@pxref{Daemon Offload Setup}). That is, always build things locally
3687 instead of offloading builds to remote machines.
3689 @item --max-silent-time=@var{seconds}
3690 When the build or substitution process remains silent for more than
3691 @var{seconds}, terminate it and report a build failure.
3693 @item --timeout=@var{seconds}
3694 Likewise, when the build or substitution process lasts for more than
3695 @var{seconds}, terminate it and report a build failure.
3697 By default there is no timeout. This behavior can be restored with
3700 @item --verbosity=@var{level}
3701 Use the given verbosity level. @var{level} must be an integer between 0
3702 and 5; higher means more verbose output. Setting a level of 4 or more
3703 may be helpful when debugging setup issues with the build daemon.
3705 @item --cores=@var{n}
3707 Allow the use of up to @var{n} CPU cores for the build. The special
3708 value @code{0} means to use as many CPU cores as available.
3710 @item --max-jobs=@var{n}
3712 Allow at most @var{n} build jobs in parallel. @xref{Invoking
3713 guix-daemon, @code{--max-jobs}}, for details about this option and the
3714 equivalent @command{guix-daemon} option.
3718 Behind the scenes, @command{guix build} is essentially an interface to
3719 the @code{package-derivation} procedure of the @code{(guix packages)}
3720 module, and to the @code{build-derivations} procedure of the @code{(guix
3721 derivations)} module.
3723 In addition to options explicitly passed on the command line,
3724 @command{guix build} and other @command{guix} commands that support
3725 building honor the @code{GUIX_BUILD_OPTIONS} environment variable.
3727 @defvr {Environment Variable} GUIX_BUILD_OPTIONS
3728 Users can define this variable to a list of command line options that
3729 will automatically be used by @command{guix build} and other
3730 @command{guix} commands that can perform builds, as in the example
3734 $ export GUIX_BUILD_OPTIONS="--no-substitutes -c 2 -L /foo/bar"
3737 These options are parsed independently, and the result is appended to
3738 the parsed command-line options.
3742 @node Invoking guix edit
3743 @section Invoking @command{guix edit}
3745 @cindex package definition, editing
3746 So many packages, so many source files! The @command{guix edit} command
3747 facilitates the life of packagers by pointing their editor at the source
3748 file containing the definition of the specified packages. For instance:
3751 guix edit gcc-4.8 vim
3755 launches the program specified in the @code{EDITOR} environment variable
3756 to edit the recipe of GCC@tie{}4.8.4 and that of Vim.
3758 If you are using Emacs, note that the Emacs user interface provides
3759 similar functionality in the ``package info'' and ``package list''
3760 buffers created by @kbd{M-x guix-search-by-name} and similar commands
3761 (@pxref{Emacs Commands}).
3764 @node Invoking guix download
3765 @section Invoking @command{guix download}
3767 When writing a package definition, developers typically need to download
3768 the package's source tarball, compute its SHA256 hash, and write that
3769 hash in the package definition (@pxref{Defining Packages}). The
3770 @command{guix download} tool helps with this task: it downloads a file
3771 from the given URI, adds it to the store, and prints both its file name
3772 in the store and its SHA256 hash.
3774 The fact that the downloaded file is added to the store saves bandwidth:
3775 when the developer eventually tries to build the newly defined package
3776 with @command{guix build}, the source tarball will not have to be
3777 downloaded again because it is already in the store. It is also a
3778 convenient way to temporarily stash files, which may be deleted
3779 eventually (@pxref{Invoking guix gc}).
3781 The @command{guix download} command supports the same URIs as used in
3782 package definitions. In particular, it supports @code{mirror://} URIs.
3783 @code{https} URIs (HTTP over TLS) are supported @emph{provided} the
3784 Guile bindings for GnuTLS are available in the user's environment; when
3785 they are not available, an error is raised. @xref{Guile Preparations,
3786 how to install the GnuTLS bindings for Guile,, gnutls-guile,
3787 GnuTLS-Guile}, for more information.
3789 The following option is available:
3792 @item --format=@var{fmt}
3794 Write the hash in the format specified by @var{fmt}. For more
3795 information on the valid values for @var{fmt}, @pxref{Invoking guix hash}.
3798 @node Invoking guix hash
3799 @section Invoking @command{guix hash}
3801 The @command{guix hash} command computes the SHA256 hash of a file.
3802 It is primarily a convenience tool for anyone contributing to the
3803 distribution: it computes the cryptographic hash of a file, which can be
3804 used in the definition of a package (@pxref{Defining Packages}).
3806 The general syntax is:
3809 guix hash @var{option} @var{file}
3812 @command{guix hash} has the following option:
3816 @item --format=@var{fmt}
3818 Write the hash in the format specified by @var{fmt}.
3820 Supported formats: @code{nix-base32}, @code{base32}, @code{base16}
3821 (@code{hex} and @code{hexadecimal} can be used as well).
3823 If the @option{--format} option is not specified, @command{guix hash}
3824 will output the hash in @code{nix-base32}. This representation is used
3825 in the definitions of packages.
3829 Compute the hash on @var{file} recursively.
3831 In this case, the hash is computed on an archive containing @var{file},
3832 including its children if it is a directory. Some of @var{file}'s
3833 meta-data is part of the archive; for instance, when @var{file} is a
3834 regular file, the hash is different depending on whether @var{file} is
3835 executable or not. Meta-data such as time stamps has no impact on the
3836 hash (@pxref{Invoking guix archive}).
3837 @c FIXME: Replace xref above with xref to an ``Archive'' section when
3842 @node Invoking guix import
3843 @section Invoking @command{guix import}
3845 @cindex importing packages
3846 @cindex package import
3847 @cindex package conversion
3848 The @command{guix import} command is useful for people willing to add a
3849 package to the distribution but who'd rather do as little work as
3850 possible to get there---a legitimate demand. The command knows of a few
3851 repositories from which it can ``import'' package meta-data. The result
3852 is a package definition, or a template thereof, in the format we know
3853 (@pxref{Defining Packages}).
3855 The general syntax is:
3858 guix import @var{importer} @var{options}@dots{}
3861 @var{importer} specifies the source from which to import package
3862 meta-data, and @var{options} specifies a package identifier and other
3863 options specific to @var{importer}. Currently, the available
3868 Import meta-data for the given GNU package. This provides a template
3869 for the latest version of that GNU package, including the hash of its
3870 source tarball, and its canonical synopsis and description.
3872 Additional information such as the package's dependencies and its
3873 license needs to be figured out manually.
3875 For example, the following command returns a package definition for
3879 guix import gnu hello
3882 Specific command-line options are:
3885 @item --key-download=@var{policy}
3886 As for @code{guix refresh}, specify the policy to handle missing OpenPGP
3887 keys when verifying the package's signature. @xref{Invoking guix
3888 refresh, @code{--key-download}}.
3893 Import meta-data from the @uref{https://pypi.python.org/, Python Package
3894 Index}@footnote{This functionality requires Guile-JSON to be installed.
3895 @xref{Requirements}.}. Information is taken from the JSON-formatted
3896 description available at @code{pypi.python.org} and usually includes all
3897 the relevant information, including package dependencies.
3899 The command below imports meta-data for the @code{itsdangerous} Python
3903 guix import pypi itsdangerous
3908 Import meta-data from @uref{https://rubygems.org/,
3909 RubyGems}@footnote{This functionality requires Guile-JSON to be
3910 installed. @xref{Requirements}.}. Information is taken from the
3911 JSON-formatted description available at @code{rubygems.org} and includes
3912 most relevant information, including runtime dependencies. There are
3913 some caveats, however. The meta-data doesn't distinguish between
3914 synopses and descriptions, so the same string is used for both fields.
3915 Additionally, the details of non-Ruby dependencies required to build
3916 native extensions is unavailable and left as an exercise to the
3919 The command below imports meta-data for the @code{rails} Ruby package:
3922 guix import gem rails
3927 Import meta-data from @uref{https://www.metacpan.org/, MetaCPAN}.
3928 Information is taken from the JSON-formatted meta-data provided through
3929 @uref{https://api.metacpan.org/, MetaCPAN's API} and includes most
3930 relevant information, such as module dependencies. License information
3931 should be checked closely. If Perl is available in the store, then the
3932 @code{corelist} utility will be used to filter core modules out of the
3933 list of dependencies.
3935 The command command below imports meta-data for the @code{Acme::Boolean}
3939 guix import cpan Acme::Boolean
3944 Import meta-data from @uref{http://cran.r-project.org/, CRAN}, the
3945 central repository for the @uref{http://r-project.org, GNU@tie{}R
3946 statistical and graphical environment}.
3948 Information is extracted from the HTML package description.
3950 The command command below imports meta-data for the @code{Cairo}
3954 guix import cran Cairo
3958 Import meta-data from a local copy of the source of the
3959 @uref{http://nixos.org/nixpkgs/, Nixpkgs distribution}@footnote{This
3960 relies on the @command{nix-instantiate} command of
3961 @uref{http://nixos.org/nix/, Nix}.}. Package definitions in Nixpkgs are
3962 typically written in a mixture of Nix-language and Bash code. This
3963 command only imports the high-level package structure that is written in
3964 the Nix language. It normally includes all the basic fields of a
3967 When importing a GNU package, the synopsis and descriptions are replaced
3968 by their canonical upstream variant.
3970 As an example, the command below imports the package definition of
3971 LibreOffice (more precisely, it imports the definition of the package
3972 bound to the @code{libreoffice} top-level attribute):
3975 guix import nix ~/path/to/nixpkgs libreoffice
3980 Import meta-data from Haskell community's central package archive
3981 @uref{https://hackage.haskell.org/, Hackage}. Information is taken from
3982 Cabal files and includes all the relevant information, including package
3985 Specific command-line options are:
3990 Read a Cabal file from the standard input.
3991 @item --no-test-dependencies
3993 Do not include dependencies required by the test suites only.
3994 @item --cabal-environment=@var{alist}
3995 @itemx -e @var{alist}
3996 @var{alist} is a Scheme alist defining the environment in which the
3997 Cabal conditionals are evaluated. The accepted keys are: @code{os},
3998 @code{arch}, @code{impl} and a string representing the name of a flag.
3999 The value associated with a flag has to be either the symbol
4000 @code{true} or @code{false}. The value associated with other keys
4001 has to conform to the Cabal file format definition. The default value
4002 associated with the keys @code{os}, @code{arch} and @code{impl} is
4003 @samp{linux}, @samp{x86_64} and @samp{ghc} respectively.
4006 The command below imports meta-data for the latest version of the
4007 @code{HTTP} Haskell package without including test dependencies and
4008 specifying the value of the flag @samp{network-uri} as @code{false}:
4011 guix import hackage -t -e "'((\"network-uri\" . false))" HTTP
4014 A specific package version may optionally be specified by following the
4015 package name by a hyphen and a version number as in the following example:
4018 guix import hackage mtl-2.1.3.1
4023 Import meta-data from an Emacs Lisp Package Archive (ELPA) package
4024 repository (@pxref{Packages,,, emacs, The GNU Emacs Manual}).
4026 Specific command-line options are:
4029 @item --archive=@var{repo}
4030 @itemx -a @var{repo}
4031 @var{repo} identifies the archive repository from which to retrieve the
4032 information. Currently the supported repositories and their identifiers
4036 @uref{http://elpa.gnu.org/packages, GNU}, selected by the @code{gnu}
4037 identifier. This is the default.
4040 @uref{http://stable.melpa.org/packages, MELPA-Stable}, selected by the
4041 @code{melpa-stable} identifier.
4044 @uref{http://melpa.org/packages, MELPA}, selected by the @code{melpa}
4050 The structure of the @command{guix import} code is modular. It would be
4051 useful to have more importers for other package formats, and your help
4052 is welcome here (@pxref{Contributing}).
4054 @node Invoking guix refresh
4055 @section Invoking @command{guix refresh}
4057 The primary audience of the @command{guix refresh} command is developers
4058 of the GNU software distribution. By default, it reports any packages
4059 provided by the distribution that are outdated compared to the latest
4060 upstream version, like this:
4064 gnu/packages/gettext.scm:29:13: gettext would be upgraded from 0.18.1.1 to 0.18.2.1
4065 gnu/packages/glib.scm:77:12: glib would be upgraded from 2.34.3 to 2.37.0
4068 It does so by browsing each package's FTP directory and determining the
4069 highest version number of the source tarballs
4070 therein@footnote{Currently, this only works for GNU packages.}.
4072 When passed @code{--update}, it modifies distribution source files to
4073 update the version numbers and source tarball hashes of those packages'
4074 recipes (@pxref{Defining Packages}). This is achieved by downloading
4075 each package's latest source tarball and its associated OpenPGP
4076 signature, authenticating the downloaded tarball against its signature
4077 using @command{gpg}, and finally computing its hash. When the public
4078 key used to sign the tarball is missing from the user's keyring, an
4079 attempt is made to automatically retrieve it from a public key server;
4080 when it's successful, the key is added to the user's keyring; otherwise,
4081 @command{guix refresh} reports an error.
4083 The following options are supported:
4089 Update distribution source files (package recipes) in place.
4090 @xref{Defining Packages}, for more information on package definitions.
4092 @item --select=[@var{subset}]
4093 @itemx -s @var{subset}
4094 Select all the packages in @var{subset}, one of @code{core} or
4097 The @code{core} subset refers to all the packages at the core of the
4098 distribution---i.e., packages that are used to build ``everything
4099 else''. This includes GCC, libc, Binutils, Bash, etc. Usually,
4100 changing one of these packages in the distribution entails a rebuild of
4101 all the others. Thus, such updates are an inconvenience to users in
4102 terms of build time or bandwidth used to achieve the upgrade.
4104 The @code{non-core} subset refers to the remaining packages. It is
4105 typically useful in cases where an update of the core packages would be
4110 In addition, @command{guix refresh} can be passed one or more package
4111 names, as in this example:
4114 guix refresh -u emacs idutils gcc-4.8.4
4118 The command above specifically updates the @code{emacs} and
4119 @code{idutils} packages. The @code{--select} option would have no
4120 effect in this case.
4122 When considering whether to upgrade a package, it is sometimes
4123 convenient to know which packages would be affected by the upgrade and
4124 should be checked for compatibility. For this the following option may
4125 be used when passing @command{guix refresh} one or more package names:
4129 @item --list-dependent
4131 List top-level dependent packages that would need to be rebuilt as a
4132 result of upgrading one or more packages.
4136 Be aware that the @code{--list-dependent} option only
4137 @emph{approximates} the rebuilds that would be required as a result of
4138 an upgrade. More rebuilds might be required under some circumstances.
4141 $ guix refresh --list-dependent flex
4142 Building the following 120 packages would ensure 213 dependent packages are rebuilt:
4143 hop-2.4.0 geiser-0.4 notmuch-0.18 mu-0.9.9.5 cflow-1.4 idutils-4.6 @dots{}
4146 The command above lists a set of packages that could be built to check
4147 for compatibility with an upgraded @code{flex} package.
4149 The following options can be used to customize GnuPG operation:
4153 @item --gpg=@var{command}
4154 Use @var{command} as the GnuPG 2.x command. @var{command} is searched
4155 for in @code{$PATH}.
4157 @item --key-download=@var{policy}
4158 Handle missing OpenPGP keys according to @var{policy}, which may be one
4163 Always download missing OpenPGP keys from the key server, and add them
4164 to the user's GnuPG keyring.
4167 Never try to download missing OpenPGP keys. Instead just bail out.
4170 When a package signed with an unknown OpenPGP key is encountered, ask
4171 the user whether to download it or not. This is the default behavior.
4174 @item --key-server=@var{host}
4175 Use @var{host} as the OpenPGP key server when importing a public key.
4179 @node Invoking guix lint
4180 @section Invoking @command{guix lint}
4181 The @command{guix lint} is meant to help package developers avoid common
4182 errors and use a consistent style. It runs a number of checks on a
4183 given set of packages in order to find common mistakes in their
4184 definitions. Available @dfn{checkers} include (see
4185 @code{--list-checkers} for a complete list):
4190 Validate certain typographical and stylistic rules about package
4191 descriptions and synopses.
4193 @item inputs-should-be-native
4194 Identify inputs that should most likely be native inputs.
4198 Probe @code{home-page} and @code{source} URLs and report those that are
4202 Warn about obvious source code formatting issues: trailing white space,
4203 use of tabulations, etc.
4206 The general syntax is:
4209 guix lint @var{options} @var{package}@dots{}
4212 If no package is given on the command line, then all packages are checked.
4213 The @var{options} may be zero or more of the following:
4219 Only enable the checkers specified in a comma-separated list using the
4220 names returned by @code{--list-checkers}.
4222 @item --list-checkers
4224 List and describe all the available checkers that will be run on packages
4229 @node Invoking guix size
4230 @section Invoking @command{guix size}
4232 The @command{guix size} command helps package developers profile the
4233 disk usage of packages. It is easy to overlook the impact of an
4234 additional dependency added to a package, or the impact of using a
4235 single output for a package that could easily be split (@pxref{Packages
4236 with Multiple Outputs}). These are the typical issues that
4237 @command{guix size} can highlight.
4239 The command can be passed a package specification such as @code{gcc-4.8}
4240 or @code{guile:debug}, or a file name in the store. Consider this
4244 $ guix size coreutils
4245 store item total self
4246 /gnu/store/@dots{}-coreutils-8.23 70.0 13.9 19.8%
4247 /gnu/store/@dots{}-gmp-6.0.0a 55.3 2.5 3.6%
4248 /gnu/store/@dots{}-acl-2.2.52 53.7 0.5 0.7%
4249 /gnu/store/@dots{}-attr-2.4.46 53.2 0.3 0.5%
4250 /gnu/store/@dots{}-gcc-4.8.4-lib 52.9 15.7 22.4%
4251 /gnu/store/@dots{}-glibc-2.21 37.2 37.2 53.1%
4255 The store items listed here constitute the @dfn{transitive closure} of
4256 Coreutils---i.e., Coreutils and all its dependencies, recursively---as
4257 would be returned by:
4260 $ guix gc -R /gnu/store/@dots{}-coreutils-8.23
4263 Here the output shows 3 columns next to store items. The first column,
4264 labeled ``total'', shows the size in mebibytes (MiB) of the closure of
4265 the store item---that is, its own size plus the size of all its
4266 dependencies. The next column, labeled ``self'', shows the size of the
4267 item itself. The last column shows the ratio of the item's size to the
4268 space occupied by all the items listed here.
4270 In this example, we see that the closure of Coreutils weighs in at
4271 70@tie{}MiB, half of which is taken by libc. (That libc represents a
4272 large fraction of the closure is not a problem @i{per se} because it is
4273 always available on the system anyway.)
4275 When the package passed to @command{guix size} is available in the
4276 store, @command{guix size} queries the daemon to determine its
4277 dependencies, and measures its size in the store, similar to @command{du
4278 -ms --apparent-size} (@pxref{du invocation,,, coreutils, GNU
4281 When the given package is @emph{not} in the store, @command{guix size}
4282 reports information based on information about the available substitutes
4283 (@pxref{Substitutes}). This allows it to profile disk usage of store
4284 items that are not even on disk, only available remotely.
4286 The available options are:
4290 @item --substitute-urls=@var{urls}
4291 Use substitute information from @var{urls}.
4292 @xref{client-substitute-urls, the same option for @code{guix build}}.
4294 @item --map-file=@var{file}
4295 Write to @var{file} a graphical map of disk usage as a PNG file.
4297 For the example above, the map looks like this:
4299 @image{images/coreutils-size-map,5in,, map of Coreutils disk usage
4300 produced by @command{guix size}}
4302 This option requires that
4303 @uref{http://wingolog.org/software/guile-charting/, Guile-Charting} be
4304 installed and visible in Guile's module search path. When that is not
4305 the case, @command{guix size} fails as it tries to load it.
4307 @item --system=@var{system}
4308 @itemx -s @var{system}
4309 Consider packages for @var{system}---e.g., @code{x86_64-linux}.
4313 @node Invoking guix graph
4314 @section Invoking @command{guix graph}
4317 Packages and their dependencies form a @dfn{graph}, specifically a
4318 directed acyclic graph (DAG). It can quickly become difficult to have a
4319 mental model of the package DAG, so the @command{guix graph} command is
4320 here to provide a visual representation of the DAG. @command{guix
4321 graph} emits a DAG representation in the input format of
4322 @uref{http://www.graphviz.org/, Graphviz}, so its output can be passed
4323 directly to Graphviz's @command{dot} command, for instance. The general
4327 guix graph @var{options} @var{package}@dots{}
4330 For example, the following command generates a PDF file representing the
4331 package DAG for the GNU@tie{}Core Utilities, showing its build-time
4335 guix graph coreutils | dot -Tpdf > dag.pdf
4338 The output looks like this:
4340 @image{images/coreutils-graph,2in,,Dependency graph of the GNU Coreutils}
4342 Nice little graph, no?
4344 But there's more than one graph! The one above is concise: it's the
4345 graph of package objects, omitting implicit inputs such as GCC, libc,
4346 grep, etc. It's often useful to have such a concise graph, but
4347 sometimes you want to see more details. @command{guix graph} supports
4348 several types of graphs, allowing you to choose the level of details:
4352 This is the default type, the one we used above. It shows the DAG of
4353 package objects, excluding implicit dependencies. It is concise, but
4354 filters out many details.
4357 This is the package DAG, @emph{including} implicit inputs.
4359 For instance, the following command:
4362 guix graph --type=bag-emerged coreutils | dot -Tpdf > dag.pdf
4365 ... yields this bigger graph:
4367 @image{images/coreutils-bag-graph,,5in,Detailed dependency graph of the GNU Coreutils}
4369 At the bottom of the graph, we see all the implicit inputs of
4370 @var{gnu-build-system} (@pxref{Build Systems, @code{gnu-build-system}}).
4372 Now, note that the dependencies of those implicit inputs---that is, the
4373 @dfn{bootstrap dependencies} (@pxref{Bootstrapping})---are not shown
4374 here, for conciseness.
4377 Similar to @code{bag-emerged}, but this time including all the bootstrap
4381 This is the most detailed representation: It shows the DAG of
4382 derivations (@pxref{Derivations}) and plain store items. Compared to
4383 the above representation, many additional nodes are visible, including
4384 builds scripts, patches, Guile modules, etc.
4388 All the above types correspond to @emph{build-time dependencies}. The
4389 following graph type represents the @emph{run-time dependencies}:
4393 This is the graph of @dfn{references} of a package output, as returned
4394 by @command{guix gc --references} (@pxref{Invoking guix gc}).
4396 If the given package output is not available in the store, @command{guix
4397 graph} attempts to obtain dependency information from substitutes.
4400 The available options are the following:
4403 @item --type=@var{type}
4404 @itemx -t @var{type}
4405 Produce a graph output of @var{type}, where @var{type} must be one of
4406 the values listed above.
4409 List the supported graph types.
4413 @node Invoking guix environment
4414 @section Invoking @command{guix environment}
4416 @cindex reproducible build environments
4417 @cindex development environments
4418 The purpose of @command{guix environment} is to assist hackers in
4419 creating reproducible development environments without polluting their
4420 package profile. The @command{guix environment} tool takes one or more
4421 packages, builds all of the necessary inputs, and creates a shell
4422 environment to use them.
4424 The general syntax is:
4427 guix environment @var{options} @var{package}@dots{}
4430 The following example spawns a new shell set up for the development of
4434 guix environment guile
4437 If the specified packages are not built yet, @command{guix environment}
4438 automatically builds them. The new shell's environment is an augmented
4439 version of the environment that @command{guix environment} was run in.
4440 It contains the necessary search paths for building the given package
4441 added to the existing environment variables. To create a ``pure''
4442 environment in which the original environment variables have been unset,
4443 use the @code{--pure} option@footnote{Users sometimes wrongfully augment
4444 environment variables such as @code{PATH} in their @file{~/.bashrc}
4445 file. As a consequence, when @code{guix environment} launches it, Bash
4446 may read @file{~/.bashrc}, thereby introducing ``impurities'' in these
4447 environment variables. It is an error to define such environment
4448 variables in @file{.bashrc}; instead, they should be defined in
4449 @file{.bash_profile}, which is sourced only by log-in shells.
4450 @xref{Bash Startup Files,,, bash, The GNU Bash Reference Manual}, for
4451 details on Bash start-up files.}.
4453 @vindex GUIX_ENVIRONMENT
4454 @command{guix environment} defines the @code{GUIX_ENVIRONMENT}
4455 variable in the shell it spaws. This allows users to, say, define a
4456 specific prompt for development environments in their @file{.bashrc}
4457 (@pxref{Bash Startup Files,,, bash, The GNU Bash Reference Manual}):
4460 if [ -n "$GUIX_ENVIRONMENT" ]
4462 export PS1="\u@@\h \w [dev]\$ "
4466 Additionally, more than one package may be specified, in which case the
4467 union of the inputs for the given packages are used. For example, the
4468 command below spawns a shell where all of the dependencies of both Guile
4469 and Emacs are available:
4472 guix environment guile emacs
4475 Sometimes an interactive shell session is not desired. The
4476 @code{--exec} option can be used to specify the command to run instead.
4479 guix environment guile --exec=make
4482 In other situations, it is more convenient to specify the list of
4483 packages needed in the environment. For example, the following command
4484 runs @command{python} from an environment containing Python@tie{}2.7 and
4488 guix environment --ad-hoc python2-numpy python-2.7 -E python
4491 The available options are summarized below.
4494 @item --expression=@var{expr}
4495 @itemx -e @var{expr}
4496 Create an environment for the package that @var{expr} evaluates to.
4498 For example, running:
4501 guix environment -e '(@@ (gnu packages maths) petsc-openmpi)'
4504 starts a shell with the environment for this specific variant of the
4507 @item --load=@var{file}
4508 @itemx -l @var{file}
4509 Create an environment for the package that the code within @var{file}
4512 As an example, @var{file} might contain a definition like this
4513 (@pxref{Defining Packages}):
4516 @verbatiminclude environment-gdb.scm
4520 @item --exec=@var{command}
4521 @item -E @var{command}
4522 Execute @var{command} in the new environment.
4525 Include all specified packages in the resulting environment, as if an
4526 @i{ad hoc} package were defined with them as inputs. This option is
4527 useful for quickly creating an environment without having to write a
4528 package expression to contain the desired inputs.
4530 For instance, the command:
4533 guix environment --ad-hoc guile guile-sdl -E guile
4536 runs @command{guile} in an environment where Guile and Guile-SDL are
4539 Note that this example implicitly asks for the default output of
4540 @code{guile} and @code{guile-sdl} but it is possible to ask for a
4541 specific output---e.g., @code{glib:bin} asks for the @code{bin} output
4542 of @code{glib} (@pxref{Packages with Multiple Outputs}).
4545 Unset existing environment variables when building the new environment.
4546 This has the effect of creating an environment in which search paths
4547 only contain package inputs.
4549 @item --search-paths
4550 Display the environment variable definitions that make up the
4553 @item --system=@var{system}
4554 @itemx -s @var{system}
4555 Attempt to build for @var{system}---e.g., @code{i686-linux}.
4558 It also supports all of the common build options that @command{guix
4559 build} supports (@pxref{Invoking guix build, common build options}).
4561 @node Invoking guix publish
4562 @section Invoking @command{guix publish}
4564 The purpose of @command{guix publish} is to enable users to easily share
4565 their store with others, which can then use it as a substitute server
4566 (@pxref{Substitutes}).
4568 When @command{guix publish} runs, it spawns an HTTP server which allows
4569 anyone with network access to obtain substitutes from it. This means
4570 that any machine running Guix can also act as if it were a build farm,
4571 since the HTTP interface is compatible with Hydra, the software behind
4572 the @code{hydra.gnu.org} build farm.
4574 For security, each substitute is signed, allowing recipients to check
4575 their authenticity and integrity (@pxref{Substitutes}). Because
4576 @command{guix publish} uses the system's signing key, which is only
4577 readable by the system administrator, it must be started as root; the
4578 @code{--user} option makes it drop root privileges early on.
4580 The general syntax is:
4583 guix publish @var{options}@dots{}
4586 Running @command{guix publish} without any additional arguments will
4587 spawn an HTTP server on port 8080:
4593 Once a publishing server has been authorized (@pxref{Invoking guix
4594 archive}), the daemon may download substitutes from it:
4597 guix-daemon --substitute-urls=http://example.org:8080
4600 The following options are available:
4603 @item --port=@var{port}
4604 @itemx -p @var{port}
4605 Listen for HTTP requests on @var{port}.
4607 @item --listen=@var{host}
4608 Listen on the network interface for @var{host}. The default is to
4609 accept connections from any interface.
4611 @item --user=@var{user}
4612 @itemx -u @var{user}
4613 Change privileges to @var{user} as soon as possible---i.e., once the
4614 server socket is open and the signing key has been read.
4616 @item --repl[=@var{port}]
4617 @itemx -r [@var{port}]
4618 Spawn a Guile REPL server (@pxref{REPL Servers,,, guile, GNU Guile
4619 Reference Manual}) on @var{port} (37146 by default). This is used
4620 primarily for debugging a running @command{guix publish} server.
4623 @c *********************************************************************
4624 @node GNU Distribution
4625 @chapter GNU Distribution
4627 @cindex Guix System Distribution
4629 Guix comes with a distribution of the GNU system consisting entirely of
4630 free software@footnote{The term ``free'' here refers to the
4631 @url{http://www.gnu.org/philosophy/free-sw.html,freedom provided to
4632 users of that software}.}. The
4633 distribution can be installed on its own (@pxref{System Installation}),
4634 but it is also possible to install Guix as a package manager on top of
4635 an installed GNU/Linux system (@pxref{Installation}). To distinguish
4636 between the two, we refer to the standalone distribution as the Guix
4637 System Distribution, or GuixSD.
4639 The distribution provides core GNU packages such as GNU libc, GCC, and
4640 Binutils, as well as many GNU and non-GNU applications. The complete
4641 list of available packages can be browsed
4642 @url{http://www.gnu.org/software/guix/packages,on-line} or by
4643 running @command{guix package} (@pxref{Invoking guix package}):
4646 guix package --list-available
4649 Our goal has been to provide a practical 100% free software distribution of
4650 Linux-based and other variants of GNU, with a focus on the promotion and
4651 tight integration of GNU components, and an emphasis on programs and
4652 tools that help users exert that freedom.
4654 Packages are currently available on the following platforms:
4659 Intel/AMD @code{x86_64} architecture, Linux-Libre kernel;
4662 Intel 32-bit architecture (IA32), Linux-Libre kernel;
4665 ARMv7-A architecture with hard float, Thumb-2 and NEON,
4666 using the EABI hard-float ABI, and Linux-Libre kernel.
4668 @item mips64el-linux
4669 little-endian 64-bit MIPS processors, specifically the Loongson series,
4670 n32 application binary interface (ABI), and Linux-Libre kernel.
4674 GuixSD itself is currently only available on @code{i686} and @code{x86_64}.
4677 For information on porting to other architectures or kernels,
4681 * System Installation:: Installing the whole operating system.
4682 * System Configuration:: Configuring the operating system.
4683 * Installing Debugging Files:: Feeding the debugger.
4684 * Security Updates:: Deploying security fixes quickly.
4685 * Package Modules:: Packages from the programmer's viewpoint.
4686 * Packaging Guidelines:: Growing the distribution.
4687 * Bootstrapping:: GNU/Linux built from scratch.
4688 * Porting:: Targeting another platform or kernel.
4691 Building this distribution is a cooperative effort, and you are invited
4692 to join! @xref{Contributing}, for information about how you can help.
4694 @node System Installation
4695 @section System Installation
4697 @cindex Guix System Distribution
4698 This section explains how to install the Guix System Distribution
4699 on a machine. The Guix package manager can
4700 also be installed on top of a running GNU/Linux system,
4701 @pxref{Installation}.
4704 @c This paragraph is for people reading this from tty2 of the
4705 @c installation image.
4706 You're reading this documentation with an Info reader. For details on
4707 how to use it, hit the @key{RET} key (``return'' or ``enter'') on the
4708 link that follows: @pxref{Help,,, info, Info: An Introduction}. Hit
4709 @kbd{l} afterwards to come back here.
4712 @subsection Limitations
4714 As of version @value{VERSION}, the Guix System Distribution (GuixSD) is
4715 not production-ready. It may contain bugs and lack important
4716 features. Thus, if you are looking for a stable production system that
4717 respects your freedom as a computer user, a good solution at this point
4718 is to consider @url{http://www.gnu.org/distros/free-distros.html, one of
4719 more established GNU/Linux distributions}. We hope you can soon switch
4720 to the GuixSD without fear, of course. In the meantime, you can
4721 also keep using your distribution and try out the package manager on top
4722 of it (@pxref{Installation}).
4724 Before you proceed with the installation, be aware of the following
4725 noteworthy limitations applicable to version @value{VERSION}:
4729 The installation process does not include a graphical user interface and
4730 requires familiarity with GNU/Linux (see the following subsections to
4731 get a feel of what that means.)
4734 The system does not yet provide full GNOME and KDE desktops. Xfce and
4735 Enlightenment are available though, if graphical desktop environments
4736 are your thing, as well as a number of X11 window managers.
4739 Support for the Logical Volume Manager (LVM) is missing.
4742 Few system services are currently supported out-of-the-box
4746 More than 2,000 packages are available, but you may
4747 occasionally find that a useful package is missing.
4750 You've been warned. But more than a disclaimer, this is an invitation
4751 to report issues (and success stories!), and join us in improving it.
4752 @xref{Contributing}, for more info.
4754 @subsection USB Stick Installation
4756 An installation image for USB sticks can be downloaded from
4757 @indicateurl{ftp://alpha.gnu.org/gnu/guix/guixsd-usb-install-@value{VERSION}.@var{system}.xz},
4758 where @var{system} is one of:
4762 for a GNU/Linux system on Intel/AMD-compatible 64-bit CPUs;
4765 for a 32-bit GNU/Linux system on Intel-compatible CPUs.
4768 This image contains a single partition with the tools necessary for an
4769 installation. It is meant to be copied @emph{as is} to a large-enough
4772 To copy the image to a USB stick, follow these steps:
4776 Decompress the image using the @command{xz} command:
4779 xz -d guixsd-usb-install-@value{VERSION}.@var{system}.xz
4783 Insert a USB stick of 1@tie{}GiB or more in your machine, and determine
4784 its device name. Assuming that USB stick is known as @file{/dev/sdX},
4785 copy the image with:
4788 dd if=guixsd-usb-install-@value{VERSION}.x86_64 of=/dev/sdX
4791 Access to @file{/dev/sdX} usually requires root privileges.
4794 Once this is done, you should be able to reboot the system and boot from
4795 the USB stick. The latter usually requires you to get in the BIOS' boot
4796 menu, where you can choose to boot from the USB stick.
4798 @subsection Preparing for Installation
4800 Once you have successfully booted the image on the USB stick, you should
4801 end up with a root prompt. Several console TTYs are configured and can
4802 be used to run commands as root. TTY2 shows this documentation,
4803 browsable using the Info reader commands (@pxref{Help,,, info, Info: An
4806 To install the system, you would:
4811 Configure the network, by running @command{ifconfig eno1 up && dhclient
4812 eno1} (to get an automatically assigned IP address from the wired
4813 network interface controller@footnote{
4814 @c http://cgit.freedesktop.org/systemd/systemd/tree/src/udev/udev-builtin-net_id.c#n20
4815 The name @code{eno1} is for the first on-board Ethernet controller. The
4816 interface name for an Ethernet controller that is in the first slot of
4817 the first PCI bus, for instance, would be @code{enp1s0}. Use
4818 @command{ifconfig -a} to list all the available network interfaces.}),
4819 or using the @command{ifconfig} command.
4821 The system automatically loads drivers for your network interface
4824 Setting up network access is almost always a requirement because the
4825 image does not contain all the software and tools that may be needed.
4828 Unless this has already been done, you must partition and format the
4831 Preferably, assign partitions a label so that you can easily and
4832 reliably refer to them in @code{file-system} declarations (@pxref{File
4833 Systems}). This is typically done using the @code{-L} option of
4834 @command{mkfs.ext4} and related commands.
4836 The installation image includes Parted (@pxref{Overview,,, parted, GNU
4837 Parted User Manual}), @command{fdisk}, Cryptsetup/LUKS for disk
4838 encryption, and e2fsprogs, the suite of tools to manipulate
4839 ext2/ext3/ext4 file systems.
4842 Once that is done, mount the target root partition under @file{/mnt}.
4845 Lastly, run @code{deco start cow-store /mnt}.
4847 This will make @file{/gnu/store} copy-on-write, such that packages added
4848 to it during the installation phase will be written to the target disk
4849 rather than kept in memory.
4854 @subsection Proceeding with the Installation
4856 With the target partitions ready, you now have to edit a file and
4857 provide the declaration of the operating system to be installed. To
4858 that end, the installation system comes with two text editors: GNU nano
4859 (@pxref{Top,,, nano, GNU nano Manual}), and GNU Zile, an Emacs clone.
4860 It is better to store that file on the target root file system, say, as
4861 @file{/mnt/etc/config.scm}.
4863 @xref{Using the Configuration System}, for examples of operating system
4864 configurations. These examples are available under
4865 @file{/etc/configuration} in the installation image, so you can copy
4866 them and use them as a starting point for your own configuration.
4868 Once you are done preparing the configuration file, the new system must
4869 be initialized (remember that the target root file system is mounted
4873 guix system init /mnt/etc/config.scm /mnt
4877 This will copy all the necessary files, and install GRUB on
4878 @file{/dev/sdX}, unless you pass the @option{--no-grub} option. For
4879 more information, @pxref{Invoking guix system}. This command may trigger
4880 downloads or builds of missing packages, which can take some time.
4882 Once that command has completed---and hopefully succeeded!---you can run
4883 @command{reboot} and boot into the new system. The @code{root} password
4884 in the new system is initially empty; other users' passwords need to be
4885 initialized by running the @command{passwd} command as @code{root},
4886 unless your configuration specifies otherwise
4887 (@pxref{user-account-password, user account passwords}).
4889 Join us on @code{#guix} on the Freenode IRC network or on
4890 @file{guix-devel@@gnu.org} to share your experience---good or not so
4893 @subsection Building the Installation Image
4895 The installation image described above was built using the @command{guix
4896 system} command, specifically:
4899 guix system disk-image --image-size=850MiB gnu/system/install.scm
4902 @xref{Invoking guix system}, for more information. See
4903 @file{gnu/system/install.scm} in the source tree for more information
4904 about the installation image.
4906 @node System Configuration
4907 @section System Configuration
4909 @cindex system configuration
4910 The Guix System Distribution supports a consistent whole-system configuration
4911 mechanism. By that we mean that all aspects of the global system
4912 configuration---such as the available system services, timezone and
4913 locale settings, user accounts---are declared in a single place. Such
4914 a @dfn{system configuration} can be @dfn{instantiated}---i.e., effected.
4916 One of the advantages of putting all the system configuration under the
4917 control of Guix is that it supports transactional system upgrades, and
4918 makes it possible to roll-back to a previous system instantiation,
4919 should something go wrong with the new one (@pxref{Features}). Another
4920 one is that it makes it easy to replicate the exact same configuration
4921 across different machines, or at different points in time, without
4922 having to resort to additional administration tools layered on top of
4923 the system's own tools.
4924 @c Yes, we're talking of Puppet, Chef, & co. here. ↑
4926 This section describes this mechanism. First we focus on the system
4927 administrator's viewpoint---explaining how the system is configured and
4928 instantiated. Then we show how this mechanism can be extended, for
4929 instance to support new system services.
4932 * Using the Configuration System:: Customizing your GNU system.
4933 * operating-system Reference:: Detail of operating-system declarations.
4934 * File Systems:: Configuring file system mounts.
4935 * Mapped Devices:: Block device extra processing.
4936 * User Accounts:: Specifying user accounts.
4937 * Locales:: Language and cultural convention settings.
4938 * Services:: Specifying system services.
4939 * Setuid Programs:: Programs running with root privileges.
4940 * X.509 Certificates:: Authenticating HTTPS servers.
4941 * Name Service Switch:: Configuring libc's name service switch.
4942 * Initial RAM Disk:: Linux-Libre bootstrapping.
4943 * GRUB Configuration:: Configuring the boot loader.
4944 * Invoking guix system:: Instantiating a system configuration.
4945 * Defining Services:: Adding new service definitions.
4948 @node Using the Configuration System
4949 @subsection Using the Configuration System
4951 The operating system is configured by providing an
4952 @code{operating-system} declaration in a file that can then be passed to
4953 the @command{guix system} command (@pxref{Invoking guix system}). A
4954 simple setup, with the default system services, the default Linux-Libre
4955 kernel, initial RAM disk, and boot loader looks like this:
4957 @findex operating-system
4959 @include os-config-bare-bones.texi
4962 This example should be self-describing. Some of the fields defined
4963 above, such as @code{host-name} and @code{bootloader}, are mandatory.
4964 Others, such as @code{packages} and @code{services}, can be omitted, in
4965 which case they get a default value.
4967 @vindex %base-packages
4968 The @code{packages} field lists
4969 packages that will be globally visible on the system, for all user
4970 accounts---i.e., in every user's @code{PATH} environment variable---in
4971 addition to the per-user profiles (@pxref{Invoking guix package}). The
4972 @var{%base-packages} variable provides all the tools one would expect
4973 for basic user and administrator tasks---including the GNU Core
4974 Utilities, the GNU Networking Utilities, the GNU Zile lightweight text
4975 editor, @command{find}, @command{grep}, etc. The example above adds
4976 Emacs to those, taken from the @code{(gnu packages emacs)} module
4977 (@pxref{Package Modules}).
4979 @vindex %base-services
4980 The @code{services} field lists @dfn{system services} to be made
4981 available when the system starts (@pxref{Services}).
4982 The @code{operating-system} declaration above specifies that, in
4983 addition to the basic services, we want the @command{lshd} secure shell
4984 daemon listening on port 2222, and allowing remote @code{root} logins
4985 (@pxref{Invoking lshd,,, lsh, GNU lsh Manual}). Under the hood,
4986 @code{lsh-service} arranges so that @code{lshd} is started with the
4987 right command-line options, possibly with supporting configuration files
4988 generated as needed (@pxref{Defining Services}). @xref{operating-system
4989 Reference}, for details about the available @code{operating-system}
4992 The configuration for a typical ``desktop'' usage, with the X11 display
4993 server, a desktop environment, network management, an SSH server, and
4994 more, would look like this:
4997 @include os-config-desktop.texi
5000 @xref{Desktop Services}, for the exact list of services provided by
5001 @var{%desktop-services}. @xref{X.509 Certificates}, for background
5002 information about the @code{nss-certs} package that is used here.
5004 Assuming the above snippet is stored in the @file{my-system-config.scm}
5005 file, the @command{guix system reconfigure my-system-config.scm} command
5006 instantiates that configuration, and makes it the default GRUB boot
5007 entry (@pxref{Invoking guix system}). The normal way to change the
5008 system's configuration is by updating this file and re-running the
5009 @command{guix system} command.
5011 At the Scheme level, the bulk of an @code{operating-system} declaration
5012 is instantiated with the following monadic procedure (@pxref{The Store
5015 @deffn {Monadic Procedure} operating-system-derivation os
5016 Return a derivation that builds @var{os}, an @code{operating-system}
5017 object (@pxref{Derivations}).
5019 The output of the derivation is a single directory that refers to all
5020 the packages, configuration files, and other supporting files needed to
5021 instantiate @var{os}.
5024 @node operating-system Reference
5025 @subsection @code{operating-system} Reference
5027 This section summarizes all the options available in
5028 @code{operating-system} declarations (@pxref{Using the Configuration
5031 @deftp {Data Type} operating-system
5032 This is the data type representing an operating system configuration.
5033 By that, we mean all the global system configuration, not per-user
5034 configuration (@pxref{Using the Configuration System}).
5037 @item @code{kernel} (default: @var{linux-libre})
5038 The package object of the operating system kernel to use@footnote{Currently
5039 only the Linux-libre kernel is supported. In the future, it will be
5040 possible to use the GNU@tie{}Hurd.}.
5042 @item @code{kernel-arguments} (default: @code{'()})
5043 List of strings or gexps representing additional arguments to pass on
5044 the kernel's command-line---e.g., @code{("console=ttyS0")}.
5046 @item @code{bootloader}
5047 The system bootloader configuration object. @xref{GRUB Configuration}.
5049 @item @code{initrd} (default: @code{base-initrd})
5050 A two-argument monadic procedure that returns an initial RAM disk for
5051 the Linux kernel. @xref{Initial RAM Disk}.
5053 @item @code{firmware} (default: @var{%base-firmware})
5055 List of firmware packages loadable by the operating system kernel.
5057 The default includes firmware needed for Atheros-based WiFi devices
5058 (Linux-libre module @code{ath9k}.)
5060 @item @code{host-name}
5063 @item @code{hosts-file}
5065 A file-like object (@pxref{G-Expressions, file-like objects}) for use as
5066 @file{/etc/hosts} (@pxref{Host Names,,, libc, The GNU C Library
5067 Reference Manual}). The default is a file with entries for
5068 @code{localhost} and @var{host-name}.
5070 @item @code{mapped-devices} (default: @code{'()})
5071 A list of mapped devices. @xref{Mapped Devices}.
5073 @item @code{file-systems}
5074 A list of file systems. @xref{File Systems}.
5076 @item @code{swap-devices} (default: @code{'()})
5077 @cindex swap devices
5078 A list of strings identifying devices to be used for ``swap space''
5079 (@pxref{Memory Concepts,,, libc, The GNU C Library Reference Manual}).
5080 For example, @code{'("/dev/sda3")}.
5082 @item @code{users} (default: @code{%base-user-accounts})
5083 @itemx @code{groups} (default: @var{%base-groups})
5084 List of user accounts and groups. @xref{User Accounts}.
5086 @item @code{skeletons} (default: @code{(default-skeletons)})
5087 A monadic list of pairs of target file name and files. These are the
5088 files that will be used as skeletons as new accounts are created.
5090 For instance, a valid value may look like this:
5093 (mlet %store-monad ((bashrc (text-file "bashrc" "\
5094 export PATH=$HOME/.guix-profile/bin")))
5095 (return `((".bashrc" ,bashrc))))
5098 @item @code{issue} (default: @var{%default-issue})
5099 A string denoting the contents of the @file{/etc/issue} file, which is
5100 what displayed when users log in on a text console.
5102 @item @code{packages} (default: @var{%base-packages})
5103 The set of packages installed in the global profile, which is accessible
5104 at @file{/run/current-system/profile}.
5106 The default set includes core utilities, but it is good practice to
5107 install non-core utilities in user profiles (@pxref{Invoking guix
5110 @item @code{timezone}
5111 A timezone identifying string---e.g., @code{"Europe/Paris"}.
5113 @item @code{locale} (default: @code{"en_US.utf8"})
5114 The name of the default locale (@pxref{Locale Names,,, libc, The GNU C
5115 Library Reference Manual}). @xref{Locales}, for more information.
5117 @item @code{locale-definitions} (default: @var{%default-locale-definitions})
5118 The list of locale definitions to be compiled and that may be used at
5119 run time. @xref{Locales}.
5121 @item @code{name-service-switch} (default: @var{%default-nss})
5122 Configuration of libc's name service switch (NSS)---a
5123 @code{<name-service-switch>} object. @xref{Name Service Switch}, for
5126 @item @code{services} (default: @var{%base-services})
5127 A list of monadic values denoting system services. @xref{Services}.
5129 @item @code{pam-services} (default: @code{(base-pam-services)})
5131 @cindex pluggable authentication modules
5132 Linux @dfn{pluggable authentication module} (PAM) services.
5133 @c FIXME: Add xref to PAM services section.
5135 @item @code{setuid-programs} (default: @var{%setuid-programs})
5136 List of string-valued G-expressions denoting setuid programs.
5137 @xref{Setuid Programs}.
5139 @item @code{sudoers-file} (default: @var{%sudoers-specification})
5140 @cindex sudoers file
5141 The contents of the @file{/etc/sudoers} file as a file-like object
5142 (@pxref{G-Expressions, @code{local-file} and @code{plain-file}}).
5144 This file specifies which users can use the @command{sudo} command, what
5145 they are allowed to do, and what privileges they may gain. The default
5146 is that only @code{root} and members of the @code{wheel} group may use
5153 @subsection File Systems
5155 The list of file systems to be mounted is specified in the
5156 @code{file-systems} field of the operating system's declaration
5157 (@pxref{Using the Configuration System}). Each file system is declared
5158 using the @code{file-system} form, like this:
5162 (mount-point "/home")
5163 (device "/dev/sda3")
5167 As usual, some of the fields are mandatory---those shown in the example
5168 above---while others can be omitted. These are described below.
5170 @deftp {Data Type} file-system
5171 Objects of this type represent file systems to be mounted. They
5172 contain the following members:
5176 This is a string specifying the type of the file system---e.g.,
5179 @item @code{mount-point}
5180 This designates the place where the file system is to be mounted.
5183 This names the ``source'' of the file system. By default it is the name
5184 of a node under @file{/dev}, but its meaning depends on the @code{title}
5185 field described below.
5187 @item @code{title} (default: @code{'device})
5188 This is a symbol that specifies how the @code{device} field is to be
5191 When it is the symbol @code{device}, then the @code{device} field is
5192 interpreted as a file name; when it is @code{label}, then @code{device}
5193 is interpreted as a partition label name; when it is @code{uuid},
5194 @code{device} is interpreted as a partition unique identifier (UUID).
5196 UUIDs may be converted from their string representation (as shown by the
5197 @command{tune2fs -l} command) using the @code{uuid} form, like this:
5201 (mount-point "/home")
5204 (device (uuid "4dab5feb-d176-45de-b287-9b0a6e4c01cb")))
5207 The @code{label} and @code{uuid} options offer a way to refer to disk
5208 partitions without having to hard-code their actual device
5209 name@footnote{Note that, while it is tempting to use
5210 @file{/dev/disk/by-uuid} and similar device names to achieve the same
5211 result, this is not recommended: These special device nodes are created
5212 by the udev daemon and may be unavailable at the time the device is
5215 However, when a file system's source is a mapped device (@pxref{Mapped
5216 Devices}), its @code{device} field @emph{must} refer to the mapped
5217 device name---e.g., @file{/dev/mapper/root-partition}---and consequently
5218 @code{title} must be set to @code{'device}. This is required so that
5219 the system knows that mounting the file system depends on having the
5220 corresponding device mapping established.
5222 @item @code{flags} (default: @code{'()})
5223 This is a list of symbols denoting mount flags. Recognized flags
5224 include @code{read-only}, @code{bind-mount}, @code{no-dev} (disallow
5225 access to special files), @code{no-suid} (ignore setuid and setgid
5226 bits), and @code{no-exec} (disallow program execution.)
5228 @item @code{options} (default: @code{#f})
5229 This is either @code{#f}, or a string denoting mount options.
5231 @item @code{needed-for-boot?} (default: @code{#f})
5232 This Boolean value indicates whether the file system is needed when
5233 booting. If that is true, then the file system is mounted when the
5234 initial RAM disk (initrd) is loaded. This is always the case, for
5235 instance, for the root file system.
5237 @item @code{check?} (default: @code{#t})
5238 This Boolean indicates whether the file system needs to be checked for
5239 errors before being mounted.
5241 @item @code{create-mount-point?} (default: @code{#f})
5242 When true, the mount point is created if it does not exist yet.
5244 @item @code{dependencies} (default: @code{'()})
5245 This is a list of @code{<file-system>} objects representing file systems
5246 that must be mounted before (and unmounted after) this one.
5248 As an example, consider a hierarchy of mounts: @file{/sys/fs/cgroup} is
5249 a dependency of @file{/sys/fs/cgroup/cpu} and
5250 @file{/sys/fs/cgroup/memory}.
5255 The @code{(gnu system file-systems)} exports the following useful
5258 @defvr {Scheme Variable} %base-file-systems
5259 These are essential file systems that are required on normal systems,
5260 such as @var{%devtmpfs-file-system} and @var{%immutable-store} (see
5261 below.) Operating system declarations should always contain at least
5265 @defvr {Scheme Variable} %devtmpfs-file-system
5266 The @code{devtmpfs} file system to be mounted on @file{/dev}. This is a
5267 requirement for udev (@pxref{Base Services, @code{udev-service}}).
5270 @defvr {Scheme Variable} %pseudo-terminal-file-system
5271 This is the file system to be mounted as @file{/dev/pts}. It supports
5272 @dfn{pseudo-terminals} created @i{via} @code{openpty} and similar
5273 functions (@pxref{Pseudo-Terminals,,, libc, The GNU C Library Reference
5274 Manual}). Pseudo-terminals are used by terminal emulators such as
5278 @defvr {Scheme Variable} %shared-memory-file-system
5279 This file system is mounted as @file{/dev/shm} and is used to support
5280 memory sharing across processes (@pxref{Memory-mapped I/O,
5281 @code{shm_open},, libc, The GNU C Library Reference Manual}).
5284 @defvr {Scheme Variable} %immutable-store
5285 This file system performs a read-only ``bind mount'' of
5286 @file{/gnu/store}, making it read-only for all the users including
5287 @code{root}. This prevents against accidental modification by software
5288 running as @code{root} or by system administrators.
5290 The daemon itself is still able to write to the store: it remounts it
5291 read-write in its own ``name space.''
5294 @defvr {Scheme Variable} %binary-format-file-system
5295 The @code{binfmt_misc} file system, which allows handling of arbitrary
5296 executable file types to be delegated to user space. This requires the
5297 @code{binfmt.ko} kernel module to be loaded.
5300 @defvr {Scheme Variable} %fuse-control-file-system
5301 The @code{fusectl} file system, which allows unprivileged users to mount
5302 and unmount user-space FUSE file systems. This requires the
5303 @code{fuse.ko} kernel module to be loaded.
5306 @node Mapped Devices
5307 @subsection Mapped Devices
5309 @cindex device mapping
5310 @cindex mapped devices
5311 The Linux kernel has a notion of @dfn{device mapping}: a block device,
5312 such as a hard disk partition, can be @dfn{mapped} into another device,
5313 with additional processing over the data that flows through
5314 it@footnote{Note that the GNU@tie{}Hurd makes no difference between the
5315 concept of a ``mapped device'' and that of a file system: both boil down
5316 to @emph{translating} input/output operations made on a file to
5317 operations on its backing store. Thus, the Hurd implements mapped
5318 devices, like file systems, using the generic @dfn{translator} mechanism
5319 (@pxref{Translators,,, hurd, The GNU Hurd Reference Manual}).}. A
5320 typical example is encryption device mapping: all writes to the mapped
5321 device are encrypted, and all reads are deciphered, transparently.
5323 Mapped devices are declared using the @code{mapped-device} form:
5327 (source "/dev/sda3")
5329 (type luks-device-mapping))
5333 @cindex disk encryption
5335 This example specifies a mapping from @file{/dev/sda3} to
5336 @file{/dev/mapper/home} using LUKS---the
5337 @url{http://code.google.com/p/cryptsetup,Linux Unified Key Setup}, a
5338 standard mechanism for disk encryption. The @file{/dev/mapper/home}
5339 device can then be used as the @code{device} of a @code{file-system}
5340 declaration (@pxref{File Systems}). The @code{mapped-device} form is
5343 @deftp {Data Type} mapped-device
5344 Objects of this type represent device mappings that will be made when
5345 the system boots up.
5349 This string specifies the name of the block device to be mapped, such as
5353 This string specifies the name of the mapping to be established. For
5354 example, specifying @code{"my-partition"} will lead to the creation of
5355 the @code{"/dev/mapper/my-partition"} device.
5358 This must be a @code{mapped-device-kind} object, which specifies how
5359 @var{source} is mapped to @var{target}.
5363 @defvr {Scheme Variable} luks-device-mapping
5364 This defines LUKS block device encryption using the @command{cryptsetup}
5365 command, from the same-named package. This relies on the
5366 @code{dm-crypt} Linux kernel module.
5370 @subsection User Accounts
5372 User accounts and groups are entirely managed through the
5373 @code{operating-system} declaration. They are specified with the
5374 @code{user-account} and @code{user-group} forms:
5380 (supplementary-groups '("wheel" ;allow use of sudo, etc.
5382 "video" ;video devices such as webcams
5383 "cdrom")) ;the good ol' CD-ROM
5384 (comment "Bob's sister")
5385 (home-directory "/home/alice"))
5388 When booting or upon completion of @command{guix system reconfigure},
5389 the system ensures that only the user accounts and groups specified in
5390 the @code{operating-system} declaration exist, and with the specified
5391 properties. Thus, account or group creations or modifications made by
5392 directly invoking commands such as @command{useradd} are lost upon
5393 reconfiguration or reboot. This ensures that the system remains exactly
5396 @deftp {Data Type} user-account
5397 Objects of this type represent user accounts. The following members may
5402 The name of the user account.
5405 This is the name (a string) or identifier (a number) of the user group
5406 this account belongs to.
5408 @item @code{supplementary-groups} (default: @code{'()})
5409 Optionally, this can be defined as a list of group names that this
5412 @item @code{uid} (default: @code{#f})
5413 This is the user ID for this account (a number), or @code{#f}. In the
5414 latter case, a number is automatically chosen by the system when the
5417 @item @code{comment} (default: @code{""})
5418 A comment about the account, such as the account's owner full name.
5420 @item @code{home-directory}
5421 This is the name of the home directory for the account.
5423 @item @code{shell} (default: Bash)
5424 This is a G-expression denoting the file name of a program to be used as
5425 the shell (@pxref{G-Expressions}).
5427 @item @code{system?} (default: @code{#f})
5428 This Boolean value indicates whether the account is a ``system''
5429 account. System accounts are sometimes treated specially; for instance,
5430 graphical login managers do not list them.
5432 @anchor{user-account-password}
5433 @item @code{password} (default: @code{#f})
5434 You would normally leave this field to @code{#f}, initialize user
5435 passwords as @code{root} with the @command{passwd} command, and then let
5436 users change it with @command{passwd}. Passwords set with
5437 @command{passwd} are of course preserved across reboot and
5440 If you @emph{do} want to have a preset password for an account, then
5441 this field must contain the encrypted password, as a string.
5442 @xref{crypt,,, libc, The GNU C Library Reference Manual}, for more information
5443 on password encryption, and @ref{Encryption,,, guile, GNU Guile Reference
5444 Manual}, for information on Guile's @code{crypt} procedure.
5449 User group declarations are even simpler:
5452 (user-group (name "students"))
5455 @deftp {Data Type} user-group
5456 This type is for, well, user groups. There are just a few fields:
5462 @item @code{id} (default: @code{#f})
5463 The group identifier (a number). If @code{#f}, a new number is
5464 automatically allocated when the group is created.
5466 @item @code{system?} (default: @code{#f})
5467 This Boolean value indicates whether the group is a ``system'' group.
5468 System groups have low numerical IDs.
5470 @item @code{password} (default: @code{#f})
5471 What, user groups can have a password? Well, apparently yes. Unless
5472 @code{#f}, this field specifies the group's password.
5477 For convenience, a variable lists all the basic user groups one may
5480 @defvr {Scheme Variable} %base-groups
5481 This is the list of basic user groups that users and/or packages expect
5482 to be present on the system. This includes groups such as ``root'',
5483 ``wheel'', and ``users'', as well as groups used to control access to
5484 specific devices such as ``audio'', ``disk'', and ``cdrom''.
5487 @defvr {Scheme Variable} %base-user-accounts
5488 This is the list of basic system accounts that programs may expect to
5489 find on a GNU/Linux system, such as the ``nobody'' account.
5491 Note that the ``root'' account is not included here. It is a
5492 special-case and is automatically added whether or not it is specified.
5499 A @dfn{locale} defines cultural conventions for a particular language
5500 and region of the world (@pxref{Locales,,, libc, The GNU C Library
5501 Reference Manual}). Each locale has a name that typically has the form
5502 @code{@var{language}_@var{territory}.@var{codeset}}---e.g.,
5503 @code{fr_LU.utf8} designates the locale for the French language, with
5504 cultural conventions from Luxembourg, and using the UTF-8 encoding.
5506 @cindex locale definition
5507 Usually, you will want to specify the default locale for the machine
5508 using the @code{locale} field of the @code{operating-system} declaration
5509 (@pxref{operating-system Reference, @code{locale}}).
5511 That locale must be among the @dfn{locale definitions} that are known to
5512 the system---and these are specified in the @code{locale-definitions}
5513 slot of @code{operating-system}. The default value includes locale
5514 definition for some widely used locales, but not for all the available
5515 locales, in order to save space.
5517 If the locale specified in the @code{locale} field is not among the
5518 definitions listed in @code{locale-definitions}, @command{guix system}
5519 raises an error. In that case, you should add the locale definition to
5520 the @code{locale-definitions} field. For instance, to add the North
5521 Frisian locale for Germany, the value of that field may be:
5524 (cons (locale-definition
5525 (name "fy_DE.utf8") (source "fy_DE"))
5526 %default-locale-definitions)
5529 Likewise, to save space, one might want @code{locale-definitions} to
5530 list only the locales that are actually used, as in:
5533 (list (locale-definition
5534 (name "ja_JP.eucjp") (source "ja_JP")
5535 (charset "EUC-JP")))
5538 The @code{locale-definition} form is provided by the @code{(gnu system
5539 locale)} module. Details are given below.
5541 @deftp {Data Type} locale-definition
5542 This is the data type of a locale definition.
5547 The name of the locale. @xref{Locale Names,,, libc, The GNU C Library
5548 Reference Manual}, for more information on locale names.
5551 The name of the source for that locale. This is typically the
5552 @code{@var{language}_@var{territory}} part of the locale name.
5554 @item @code{charset} (default: @code{"UTF-8"})
5555 The ``character set'' or ``code set'' for that locale,
5556 @uref{http://www.iana.org/assignments/character-sets, as defined by
5562 @defvr {Scheme Variable} %default-locale-definitions
5563 An arbitrary list of commonly used UTF-8 locales, used as the default
5564 value of the @code{locale-definitions} field of @code{operating-system}
5568 @cindex normalized codeset in locale names
5569 These locale definitions use the @dfn{normalized codeset} for the part
5570 that follows the dot in the name (@pxref{Using gettextized software,
5571 normalized codeset,, libc, The GNU C Library Reference Manual}). So for
5572 instance it has @code{uk_UA.utf8} but @emph{not}, say,
5577 @subsection Services
5579 @cindex system services
5580 An important part of preparing an @code{operating-system} declaration is
5581 listing @dfn{system services} and their configuration (@pxref{Using the
5582 Configuration System}). System services are typically daemons launched
5583 when the system boots, or other actions needed at that time---e.g.,
5584 configuring network access.
5586 Services are managed by GNU@tie{}dmd (@pxref{Introduction,,, dmd, GNU
5587 dmd Manual}). On a running system, the @command{deco} command allows
5588 you to list the available services, show their status, start and stop
5589 them, or do other specific operations (@pxref{Jump Start,,, dmd, GNU dmd
5590 Manual}). For example:
5596 The above command, run as @code{root}, lists the currently defined
5597 services. The @command{deco doc} command shows a synopsis of the given
5602 Run libc's name service cache daemon (nscd).
5605 The @command{start}, @command{stop}, and @command{restart} sub-commands
5606 have the effect you would expect. For instance, the commands below stop
5607 the nscd service and restart the Xorg display server:
5611 Service nscd has been stopped.
5612 # deco restart xorg-server
5613 Service xorg-server has been stopped.
5614 Service xorg-server has been started.
5617 The following sections document the available services, starting with
5618 the core services, that may be used in an @code{operating-system}
5622 * Base Services:: Essential system services.
5623 * Networking Services:: Network setup, SSH daemon, etc.
5624 * X Window:: Graphical display.
5625 * Desktop Services:: D-Bus and desktop services.
5626 * Database Services:: SQL databases.
5627 * Web Services:: Web servers.
5628 * Various Services:: Other services.
5632 @subsubsection Base Services
5634 The @code{(gnu services base)} module provides definitions for the basic
5635 services that one expects from the system. The services exported by
5636 this module are listed below.
5638 @defvr {Scheme Variable} %base-services
5639 This variable contains a list of basic services@footnote{Technically,
5640 this is a list of monadic services. @xref{The Store Monad}.} one would
5641 expect from the system: a login service (mingetty) on each tty, syslogd,
5642 libc's name service cache daemon (nscd), the udev device manager, and
5645 This is the default value of the @code{services} field of
5646 @code{operating-system} declarations. Usually, when customizing a
5647 system, you will want to append services to @var{%base-services}, like
5651 (cons* (avahi-service) (lsh-service) %base-services)
5655 @deffn {Monadic Procedure} host-name-service @var{name}
5656 Return a service that sets the host name to @var{name}.
5659 @deffn {Monadic Procedure} mingetty-service @var{tty} [#:motd] @
5660 [#:auto-login #f] [#:login-program] [#:login-pause? #f] @
5661 [#:allow-empty-passwords? #f]
5662 Return a service to run mingetty on @var{tty}.
5664 When @var{allow-empty-passwords?} is true, allow empty log-in password. When
5665 @var{auto-login} is true, it must be a user name under which to log-in
5666 automatically. @var{login-pause?} can be set to @code{#t} in conjunction with
5667 @var{auto-login}, in which case the user will have to press a key before the
5668 login shell is launched.
5670 When true, @var{login-program} is a gexp or a monadic gexp denoting the name
5671 of the log-in program (the default is the @code{login} program from the Shadow
5674 @var{motd} is a monadic value containing a text file to use as
5675 the ``message of the day''.
5678 @cindex name service cache daemon
5680 @deffn {Monadic Procedure} nscd-service [@var{config}] [#:glibc glibc] @
5681 [#:name-services '()]
5682 Return a service that runs libc's name service cache daemon (nscd) with
5683 the given @var{config}---an @code{<nscd-configuration>} object.
5684 Optionally, @code{#:name-services} is a list of packages that provide
5685 name service switch (NSS) modules needed by nscd. @xref{Name Service
5686 Switch}, for an example.
5689 @defvr {Scheme Variable} %nscd-default-configuration
5690 This is the default @code{<nscd-configuration>} value (see below) used
5691 by @code{nscd-service}. This uses the caches defined by
5692 @var{%nscd-default-caches}; see below.
5695 @deftp {Data Type} nscd-configuration
5696 This is the type representing the name service cache daemon (nscd)
5701 @item @code{log-file} (default: @code{"/var/log/nscd.log"})
5702 Name of nscd's log file. This is where debugging output goes when
5703 @code{debug-level} is strictly positive.
5705 @item @code{debug-level} (default: @code{0})
5706 Integer denoting the debugging levels. Higher numbers mean more
5707 debugging output is logged.
5709 @item @code{caches} (default: @var{%nscd-default-caches})
5710 List of @code{<nscd-cache>} objects denoting things to be cached; see
5716 @deftp {Data Type} nscd-cache
5717 Data type representing a cache database of nscd and its parameters.
5721 @item @code{database}
5722 This is a symbol representing the name of the database to be cached.
5723 Valid values are @code{passwd}, @code{group}, @code{hosts}, and
5724 @code{services}, which designate the corresponding NSS database
5725 (@pxref{NSS Basics,,, libc, The GNU C Library Reference Manual}).
5727 @item @code{positive-time-to-live}
5728 @itemx @code{negative-time-to-live} (default: @code{20})
5729 A number representing the number of seconds during which a positive or
5730 negative lookup result remains in cache.
5732 @item @code{check-files?} (default: @code{#t})
5733 Whether to check for updates of the files corresponding to
5736 For instance, when @var{database} is @code{hosts}, setting this flag
5737 instructs nscd to check for updates in @file{/etc/hosts} and to take
5740 @item @code{persistent?} (default: @code{#t})
5741 Whether the cache should be stored persistently on disk.
5743 @item @code{shared?} (default: @code{#t})
5744 Whether the cache should be shared among users.
5746 @item @code{max-database-size} (default: 32@tie{}MiB)
5747 Maximum size in bytes of the database cache.
5749 @c XXX: 'suggested-size' and 'auto-propagate?' seem to be expert
5750 @c settings, so leave them out.
5755 @defvr {Scheme Variable} %nscd-default-caches
5756 List of @code{<nscd-cache>} objects used by default by
5757 @code{nscd-configuration} (see above.)
5759 It enables persistent and aggressive caching of service and host name
5760 lookups. The latter provides better host name lookup performance,
5761 resilience in the face of unreliable name servers, and also better
5762 privacy---often the result of host name lookups is in local cache, so
5763 external name servers do not even need to be queried.
5767 @deffn {Monadic Procedure} syslog-service [#:config-file #f]
5768 Return a service that runs @code{syslogd}. If configuration file name
5769 @var{config-file} is not specified, use some reasonable default
5773 @deffn {Monadic Procedure} guix-service [#:guix guix] @
5774 [#:builder-group "guixbuild"] [#:build-accounts 10] @
5775 [#:authorize-hydra-key? #t] [#:use-substitutes? #t] @
5776 [#:extra-options '()]
5777 Return a service that runs the build daemon from @var{guix}, and has
5778 @var{build-accounts} user accounts available under @var{builder-group}.
5780 When @var{authorize-hydra-key?} is true, the @code{hydra.gnu.org} public key
5781 provided by @var{guix} is authorized upon activation, meaning that substitutes
5782 from @code{hydra.gnu.org} are used by default.
5784 If @var{use-substitutes?} is false, the daemon is run with
5785 @option{--no-substitutes} (@pxref{Invoking guix-daemon,
5786 @option{--no-substitutes}}).
5788 Finally, @var{extra-options} is a list of additional command-line options
5789 passed to @command{guix-daemon}.
5792 @deffn {Monadic Procedure} udev-service [#:udev udev]
5793 Run @var{udev}, which populates the @file{/dev} directory dynamically.
5796 @deffn {Monadic Procedure} console-keymap-service @var{file}
5797 Return a service to load console keymap from @var{file} using
5798 @command{loadkeys} command.
5802 @node Networking Services
5803 @subsubsection Networking Services
5805 The @code{(gnu services networking)} module provides services to configure
5806 the network interface.
5808 @cindex DHCP, networking service
5809 @deffn {Monadic Procedure} dhcp-client-service [#:dhcp @var{isc-dhcp}]
5810 Return a service that runs @var{dhcp}, a Dynamic Host Configuration
5811 Protocol (DHCP) client, on all the non-loopback network interfaces.
5814 @deffn {Monadic Procedure} static-networking-service @var{interface} @var{ip} @
5815 [#:gateway #f] [#:name-services @code{'()}]
5816 Return a service that starts @var{interface} with address @var{ip}. If
5817 @var{gateway} is true, it must be a string specifying the default network
5822 @deffn {Monadic Procedure} wicd-service [#:wicd @var{wicd}]
5823 Return a service that runs @url{https://launchpad.net/wicd,Wicd}, a
5824 network manager that aims to simplify wired and wireless networking.
5827 @deffn {Monadic Procedure} ntp-service [#:ntp @var{ntp}] @
5828 [#:name-service @var{%ntp-servers}]
5829 Return a service that runs the daemon from @var{ntp}, the
5830 @uref{http://www.ntp.org, Network Time Protocol package}. The daemon will
5831 keep the system clock synchronized with that of @var{servers}.
5834 @defvr {Scheme Variable} %ntp-servers
5835 List of host names used as the default NTP servers.
5838 @deffn {Monadic Procedure} tor-service [#:tor tor]
5839 Return a service to run the @uref{https://torproject.org,Tor} daemon.
5841 The daemon runs with the default settings (in particular the default exit
5842 policy) as the @code{tor} unprivileged user.
5845 @deffn {Monadic Procedure} bitlbee-service [#:bitlbee bitlbee] @
5846 [#:interface "127.0.0.1"] [#:port 6667] @
5847 [#:extra-settings ""]
5848 Return a service that runs @url{http://bitlbee.org,BitlBee}, a daemon that
5849 acts as a gateway between IRC and chat networks.
5851 The daemon will listen to the interface corresponding to the IP address
5852 specified in @var{interface}, on @var{port}. @code{127.0.0.1} means that only
5853 local clients can connect, whereas @code{0.0.0.0} means that connections can
5854 come from any networking interface.
5856 In addition, @var{extra-settings} specifies a string to append to the
5860 Furthermore, @code{(gnu services ssh)} provides the following service.
5862 @deffn {Monadic Procedure} lsh-service [#:host-key "/etc/lsh/host-key"] @
5863 [#:daemonic? #t] [#:interfaces '()] [#:port-number 22] @
5864 [#:allow-empty-passwords? #f] [#:root-login? #f] @
5865 [#:syslog-output? #t] [#:x11-forwarding? #t] @
5866 [#:tcp/ip-forwarding? #t] [#:password-authentication? #t] @
5867 [#:public-key-authentication? #t] [#:initialize? #t]
5868 Run the @command{lshd} program from @var{lsh} to listen on port @var{port-number}.
5869 @var{host-key} must designate a file containing the host key, and readable
5872 When @var{daemonic?} is true, @command{lshd} will detach from the
5873 controlling terminal and log its output to syslogd, unless one sets
5874 @var{syslog-output?} to false. Obviously, it also makes lsh-service
5875 depend on existence of syslogd service. When @var{pid-file?} is true,
5876 @command{lshd} writes its PID to the file called @var{pid-file}.
5878 When @var{initialize?} is true, automatically create the seed and host key
5879 upon service activation if they do not exist yet. This may take long and
5880 require interaction.
5882 When @var{initialize?} is false, it is up to the user to initialize the
5883 randomness generator (@pxref{lsh-make-seed,,, lsh, LSH Manual}), and to create
5884 a key pair with the private key stored in file @var{host-key} (@pxref{lshd
5885 basics,,, lsh, LSH Manual}).
5887 When @var{interfaces} is empty, lshd listens for connections on all the
5888 network interfaces; otherwise, @var{interfaces} must be a list of host names
5891 @var{allow-empty-passwords?} specifies whether to accept log-ins with empty
5892 passwords, and @var{root-login?} specifies whether to accept log-ins as
5895 The other options should be self-descriptive.
5898 @defvr {Scheme Variable} %facebook-host-aliases
5899 This variable contains a string for use in @file{/etc/hosts}
5900 (@pxref{Host Names,,, libc, The GNU C Library Reference Manual}). Each
5901 line contains a entry that maps a known server name of the Facebook
5902 on-line service---e.g., @code{www.facebook.com}---to the local
5903 host---@code{127.0.0.1} or its IPv6 equivalent, @code{::1}.
5905 This variable is typically used in the @code{hosts-file} field of an
5906 @code{operating-system} declaration (@pxref{operating-system Reference,
5907 @file{/etc/hosts}}):
5910 (use-modules (gnu) (guix))
5913 (host-name "mymachine")
5916 ;; Create a /etc/hosts file with aliases for "localhost"
5917 ;; and "mymachine", as well as for Facebook servers.
5919 (string-append (local-host-aliases host-name)
5920 %facebook-host-aliases))))
5923 This mechanism can prevent programs running locally, such as Web
5924 browsers, from accessing Facebook.
5927 The @code{(gnu services avahi)} provides the following definition.
5929 @deffn {Monadic Procedure} avahi-service [#:avahi @var{avahi}] @
5930 [#:host-name #f] [#:publish? #t] [#:ipv4? #t] @
5931 [#:ipv6? #t] [#:wide-area? #f] @
5932 [#:domains-to-browse '()]
5933 Return a service that runs @command{avahi-daemon}, a system-wide
5934 mDNS/DNS-SD responder that allows for service discovery and
5935 "zero-configuration" host name lookups (see @uref{http://avahi.org/}).
5937 If @var{host-name} is different from @code{#f}, use that as the host name to
5938 publish for this machine; otherwise, use the machine's actual host name.
5940 When @var{publish?} is true, publishing of host names and services is allowed;
5941 in particular, avahi-daemon will publish the machine's host name and IP
5942 address via mDNS on the local network.
5944 When @var{wide-area?} is true, DNS-SD over unicast DNS is enabled.
5946 Boolean values @var{ipv4?} and @var{ipv6?} determine whether to use IPv4/IPv6
5952 @subsubsection X Window
5954 Support for the X Window graphical display system---specifically
5955 Xorg---is provided by the @code{(gnu services xorg)} module. Note that
5956 there is no @code{xorg-service} procedure. Instead, the X server is
5957 started by the @dfn{login manager}, currently SLiM.
5959 @deffn {Monadic Procedure} slim-service [#:allow-empty-passwords? #f] @
5960 [#:auto-login? #f] [#:default-user ""] [#:startx] @
5961 [#:theme @var{%default-slim-theme}] @
5962 [#:theme-name @var{%default-slim-theme-name}]
5963 Return a service that spawns the SLiM graphical login manager, which in
5964 turn starts the X display server with @var{startx}, a command as returned by
5965 @code{xorg-start-command}.
5969 SLiM automatically looks for session types described by the @file{.desktop}
5970 files in @file{/run/current-system/profile/share/xsessions} and allows users
5971 to choose a session from the log-in screen using @kbd{F1}. Packages such as
5972 @var{xfce}, @var{sawfish}, and @var{ratpoison} provide @file{.desktop} files;
5973 adding them to the system-wide set of packages automatically makes them
5974 available at the log-in screen.
5976 In addition, @file{~/.xsession} files are honored. When available,
5977 @file{~/.xsession} must be an executable that starts a window manager
5978 and/or other X clients.
5980 When @var{allow-empty-passwords?} is true, allow logins with an empty
5981 password. When @var{auto-login?} is true, log in automatically as
5984 If @var{theme} is @code{#f}, the use the default log-in theme; otherwise
5985 @var{theme} must be a gexp denoting the name of a directory containing the
5986 theme to use. In that case, @var{theme-name} specifies the name of the
5990 @defvr {Scheme Variable} %default-theme
5991 @defvrx {Scheme Variable} %default-theme-name
5992 The G-Expression denoting the default SLiM theme and its name.
5995 @deffn {Monadic Procedure} xorg-start-command [#:guile] @
5996 [#:configuration-file #f] [#:xorg-server @var{xorg-server}]
5997 Return a derivation that builds a @var{guile} script to start the X server
5998 from @var{xorg-server}. @var{configuration-file} is the server configuration
5999 file or a derivation that builds it; when omitted, the result of
6000 @code{xorg-configuration-file} is used.
6002 Usually the X server is started by a login manager.
6005 @deffn {Monadic Procedure} xorg-configuration-file @
6006 [#:drivers '()] [#:resolutions '()] [#:extra-config '()]
6007 Return a configuration file for the Xorg server containing search paths for
6008 all the common drivers.
6010 @var{drivers} must be either the empty list, in which case Xorg chooses a
6011 graphics driver automatically, or a list of driver names that will be tried in
6012 this order---e.g., @code{(\"modesetting\" \"vesa\")}.
6014 Likewise, when @var{resolutions} is the empty list, Xorg chooses an
6015 appropriate screen resolution; otherwise, it must be a list of
6016 resolutions---e.g., @code{((1024 768) (640 480))}.
6018 Last, @var{extra-config} is a list of strings or objects appended to the
6019 @code{text-file*} argument list. It is used to pass extra text to be added
6020 verbatim to the configuration file.
6023 @node Desktop Services
6024 @subsubsection Desktop Services
6026 The @code{(gnu services desktop)} module provides services that are
6027 usually useful in the context of a ``desktop'' setup---that is, on a
6028 machine running a graphical display server, possibly with graphical user
6031 To simplify things, the module defines a variable containing the set of
6032 services that users typically expect on a machine with a graphical
6033 environment and networking:
6035 @defvr {Scheme Variable} %desktop-services
6036 This is a list of services that builds upon @var{%base-services} and
6037 adds or adjust services for a typical ``desktop'' setup.
6039 In particular, it adds a graphical login manager (@pxref{X Window,
6040 @code{slim-service}}), a network management tool (@pxref{Networking
6041 Services, @code{wicd-service}}), energy and color management services,
6042 the GeoClue location service, an NTP client (@pxref{Networking
6043 Services}), the Avahi daemon, and has the name service switch service
6044 configured to be able to use @code{nss-mdns} (@pxref{Name Service
6048 The @var{%desktop-services} variable can be used as the @code{services}
6049 field of an @code{operating-system} declaration (@pxref{operating-system
6050 Reference, @code{services}}).
6052 The actual service definitions provided by @code{(gnu services desktop)}
6053 are described below.
6055 @deffn {Monadic Procedure} dbus-service @var{services} @
6057 Return a service that runs the ``system bus'', using @var{dbus}, with
6058 support for @var{services}.
6060 @uref{http://dbus.freedesktop.org/, D-Bus} is an inter-process communication
6061 facility. Its system bus is used to allow system services to communicate
6062 and be notified of system-wide events.
6064 @var{services} must be a list of packages that provide an
6065 @file{etc/dbus-1/system.d} directory containing additional D-Bus configuration
6066 and policy files. For example, to allow avahi-daemon to use the system bus,
6067 @var{services} must be equal to @code{(list avahi)}.
6070 @deffn {Monadic Procedure} upower-service [#:upower @var{upower}] @
6071 [#:watts-up-pro? #f] @
6072 [#:poll-batteries? #t] @
6073 [#:ignore-lid? #f] @
6074 [#:use-percentage-for-policy? #f] @
6075 [#:percentage-low 10] @
6076 [#:percentage-critical 3] @
6077 [#:percentage-action 2] @
6079 [#:time-critical 300] @
6080 [#:time-action 120] @
6081 [#:critical-power-action 'hybrid-sleep]
6082 Return a service that runs @uref{http://upower.freedesktop.org/,
6083 @command{upowerd}}, a system-wide monitor for power consumption and battery
6084 levels, with the given configuration settings. It implements the
6085 @code{org.freedesktop.UPower} D-Bus interface, and is notably used by
6089 @deffn {Monadic Procedure} colord-service [#:colord @var{colord}]
6090 Return a service that runs @command{colord}, a system service with a D-Bus
6091 interface to manage the color profiles of input and output devices such as
6092 screens and scanners. It is notably used by the GNOME Color Manager graphical
6093 tool. See @uref{http://www.freedesktop.org/software/colord/, the colord web
6094 site} for more information.
6097 @deffn {Scheme Procedure} geoclue-application name [#:allowed? #t] [#:system? #f] [#:users '()]
6098 Return an configuration allowing an application to access GeoClue
6099 location data. @var{name} is the Desktop ID of the application, without
6100 the @code{.desktop} part. If @var{allowed?} is true, the application
6101 will have access to location information by default. The boolean
6102 @var{system?} value indicates that an application is a system component
6103 or not. Finally @var{users} is a list of UIDs of all users for which
6104 this application is allowed location info access. An empty users list
6105 means that all users are allowed.
6108 @defvr {Scheme Variable} %standard-geoclue-applications
6109 The standard list of well-known GeoClue application configurations,
6110 granting authority to GNOME's date-and-time utility to ask for the
6111 current location in order to set the time zone, and allowing the Firefox
6112 (IceCat) and Epiphany web browsers to request location information.
6113 Firefox and Epiphany both query the user before allowing a web page to
6114 know the user's location.
6117 @deffn {Monadic Procedure} geoclue-service [#:colord @var{colord}] @
6119 [#:wifi-geolocation-url "https://location.services.mozilla.com/v1/geolocate?key=geoclue"] @
6121 [#:wifi-submission-url "https://location.services.mozilla.com/v1/submit?key=geoclue"] @
6122 [#:submission-nick "geoclue"] @
6123 [#:applications %standard-geoclue-applications]
6124 Return a service that runs the GeoClue location service. This service
6125 provides a D-Bus interface to allow applications to request access to a
6126 user's physical location, and optionally to add information to online
6127 location databases. See
6128 @uref{https://wiki.freedesktop.org/www/Software/GeoClue/, the GeoClue
6129 web site} for more information.
6132 @node Database Services
6133 @subsubsection Database Services
6135 The @code{(gnu services databases)} module provides the following service.
6137 @deffn {Monadic Procedure} postgresql-service [#:postgresql postgresql] @
6138 [#:config-file] [#:data-directory ``/var/lib/postgresql/data'']
6139 Return a service that runs @var{postgresql}, the PostgreSQL database
6142 The PostgreSQL daemon loads its runtime configuration from
6143 @var{config-file} and stores the database cluster in
6144 @var{data-directory}.
6148 @subsubsection Web Services
6150 The @code{(gnu services web)} module provides the following service:
6152 @deffn {Monadic Procedure} nginx-service [#:nginx nginx] @
6153 [#:log-directory ``/var/log/nginx''] @
6154 [#:run-directory ``/var/run/nginx''] @
6157 Return a service that runs @var{nginx}, the nginx web server.
6159 The nginx daemon loads its runtime configuration from @var{config-file}.
6160 Log files are written to @var{log-directory} and temporary runtime data
6161 files are written to @var{run-directory}. For proper operation, these
6162 arguments should match what is in @var{config-file} to ensure that the
6163 directories are created when the service is activated.
6167 @node Various Services
6168 @subsubsection Various Services
6170 The @code{(gnu services lirc)} module provides the following service.
6172 @deffn {Monadic Procedure} lirc-service [#:lirc lirc] @
6173 [#:device #f] [#:driver #f] [#:config-file #f] @
6174 [#:extra-options '()]
6175 Return a service that runs @url{http://www.lirc.org,LIRC}, a daemon that
6176 decodes infrared signals from remote controls.
6178 Optionally, @var{device}, @var{driver} and @var{config-file}
6179 (configuration file name) may be specified. See @command{lircd} manual
6182 Finally, @var{extra-options} is a list of additional command-line options
6183 passed to @command{lircd}.
6187 @node Setuid Programs
6188 @subsection Setuid Programs
6190 @cindex setuid programs
6191 Some programs need to run with ``root'' privileges, even when they are
6192 launched by unprivileged users. A notorious example is the
6193 @command{passwd} program, which users can run to change their
6194 password, and which needs to access the @file{/etc/passwd} and
6195 @file{/etc/shadow} files---something normally restricted to root, for
6196 obvious security reasons. To address that, these executables are
6197 @dfn{setuid-root}, meaning that they always run with root privileges
6198 (@pxref{How Change Persona,,, libc, The GNU C Library Reference Manual},
6199 for more info about the setuid mechanisms.)
6201 The store itself @emph{cannot} contain setuid programs: that would be a
6202 security issue since any user on the system can write derivations that
6203 populate the store (@pxref{The Store}). Thus, a different mechanism is
6204 used: instead of changing the setuid bit directly on files that are in
6205 the store, we let the system administrator @emph{declare} which programs
6206 should be setuid root.
6208 The @code{setuid-programs} field of an @code{operating-system}
6209 declaration contains a list of G-expressions denoting the names of
6210 programs to be setuid-root (@pxref{Using the Configuration System}).
6211 For instance, the @command{passwd} program, which is part of the Shadow
6212 package, can be designated by this G-expression (@pxref{G-Expressions}):
6215 #~(string-append #$shadow "/bin/passwd")
6218 A default set of setuid programs is defined by the
6219 @code{%setuid-programs} variable of the @code{(gnu system)} module.
6221 @defvr {Scheme Variable} %setuid-programs
6222 A list of G-expressions denoting common programs that are setuid-root.
6224 The list includes commands such as @command{passwd}, @command{ping},
6225 @command{su}, and @command{sudo}.
6228 Under the hood, the actual setuid programs are created in the
6229 @file{/run/setuid-programs} directory at system activation time. The
6230 files in this directory refer to the ``real'' binaries, which are in the
6233 @node X.509 Certificates
6234 @subsection X.509 Certificates
6236 @cindex HTTPS, certificates
6237 @cindex X.509 certificates
6239 Web servers available over HTTPS (that is, HTTP over the transport-layer
6240 security mechanism, TLS) send client programs an @dfn{X.509 certificate}
6241 that the client can then use to @emph{authenticate} the server. To do
6242 that, clients verify that the server's certificate is signed by a
6243 so-called @dfn{certificate authority} (CA). But to verify the CA's
6244 signature, clients must have first acquired the CA's certificate.
6246 Web browsers such as GNU@tie{}IceCat include their own set of CA
6247 certificates, such that they are able to verify CA signatures
6250 However, most other programs that can talk HTTPS---@command{wget},
6251 @command{git}, @command{w3m}, etc.---need to be told where CA
6252 certificates can be found.
6254 @cindex @code{nss-certs}
6255 In GuixSD, this is done by adding a package that provides certificates
6256 to the @code{packages} field of the @code{operating-system} declaration
6257 (@pxref{operating-system Reference}). GuixSD includes one such package,
6258 @code{nss-certs}, which is a set of CA certificates provided as part of
6259 Mozilla's Network Security Services.
6261 Note that it is @emph{not} part of @var{%base-packages}, so you need to
6262 explicitly add it. The @file{/etc/ssl/certs} directory, which is where
6263 most applications and libraries look for certificates by default, points
6264 to the certificates installed globally.
6266 Unprivileged users can also install their own certificate package in
6267 their profile. A number of environment variables need to be defined so
6268 that applications and libraries know where to find them. Namely, the
6269 OpenSSL library honors the @code{SSL_CERT_DIR} and @code{SSL_CERT_FILE}
6270 variables. Some applications add their own environment variables; for
6271 instance, the Git version control system honors the certificate bundle
6272 pointed to by the @code{GIT_SSL_CAINFO} environment variable.
6275 @node Name Service Switch
6276 @subsection Name Service Switch
6278 @cindex name service switch
6280 The @code{(gnu system nss)} module provides bindings to the
6281 configuration file of libc's @dfn{name service switch} or @dfn{NSS}
6282 (@pxref{NSS Configuration File,,, libc, The GNU C Library Reference
6283 Manual}). In a nutshell, the NSS is a mechanism that allows libc to be
6284 extended with new ``name'' lookup methods for system databases, which
6285 includes host names, service names, user accounts, and more (@pxref{Name
6286 Service Switch, System Databases and Name Service Switch,, libc, The GNU
6287 C Library Reference Manual}).
6289 The NSS configuration specifies, for each system database, which lookup
6290 method is to be used, and how the various methods are chained
6291 together---for instance, under which circumstances NSS should try the
6292 next method in the list. The NSS configuration is given in the
6293 @code{name-service-switch} field of @code{operating-system} declarations
6294 (@pxref{operating-system Reference, @code{name-service-switch}}).
6297 @cindex .local, host name lookup
6298 As an example, the declaration below configures the NSS to use the
6299 @uref{http://0pointer.de/lennart/projects/nss-mdns/, @code{nss-mdns}
6300 back-end}, which supports host name lookups over multicast DNS (mDNS)
6301 for host names ending in @code{.local}:
6304 (name-service-switch
6305 (hosts (list %files ;first, check /etc/hosts
6307 ;; If the above did not succeed, try
6308 ;; with 'mdns_minimal'.
6310 (name "mdns_minimal")
6312 ;; 'mdns_minimal' is authoritative for
6313 ;; '.local'. When it returns "not found",
6314 ;; no need to try the next methods.
6315 (reaction (lookup-specification
6316 (not-found => return))))
6318 ;; Then fall back to DNS.
6322 ;; Finally, try with the "full" 'mdns'.
6327 Don't worry: the @code{%mdns-host-lookup-nss} variable (see below)
6328 contains this configuration, so you won't have to type it if all you
6329 want is to have @code{.local} host lookup working.
6331 Note that, in this case, in addition to setting the
6332 @code{name-service-switch} of the @code{operating-system} declaration,
6333 @code{nscd-service} must be told where to find the @code{nss-mdns}
6334 shared library (@pxref{Base Services, @code{nscd-service}}). Since the
6335 @code{nscd} service is part of @var{%base-services}, you may want to
6336 customize it by adding this snippet in the operating system
6340 (use-modules (guix) (gnu))
6342 (define %my-base-services
6343 ;; Replace the default nscd service with one that knows
6345 (map (lambda (mservice)
6346 ;; "Bind" the MSERVICE monadic value to inspect it.
6347 (mlet %store-monad ((service mservice))
6348 (if (member 'nscd (service-provision service))
6349 (nscd-service (nscd-configuration)
6350 #:name-services (list nss-mdns))
6356 @dots{} and then refer to @var{%my-base-services} instead of
6357 @var{%base-services} in the @code{operating-system} declaration.
6358 Lastly, this relies on the availability of the Avahi service
6359 (@pxref{Networking Services, @code{avahi-service}}).
6361 For convenience, the following variables provide typical NSS
6364 @defvr {Scheme Variable} %default-nss
6365 This is the default name service switch configuration, a
6366 @code{name-service-switch} object.
6369 @defvr {Scheme Variable} %mdns-host-lookup-nss
6370 This is the name service switch configuration with support for host name
6371 lookup over multicast DNS (mDNS) for host names ending in @code{.local}.
6374 The reference for name service switch configuration is given below. It
6375 is a direct mapping of the C library's configuration file format, so
6376 please refer to the C library manual for more information (@pxref{NSS
6377 Configuration File,,, libc, The GNU C Library Reference Manual}).
6378 Compared to libc's NSS configuration file format, it has the advantage
6379 not only of adding this warm parenthetic feel that we like, but also
6380 static checks: you'll know about syntax errors and typos as soon as you
6381 run @command{guix system}.
6383 @deftp {Data Type} name-service-switch
6385 This is the data type representation the configuration of libc's name
6386 service switch (NSS). Each field below represents one of the supported
6403 The system databases handled by the NSS. Each of these fields must be a
6404 list of @code{<name-service>} objects (see below.)
6408 @deftp {Data Type} name-service
6410 This is the data type representing an actual name service and the
6411 associated lookup action.
6415 A string denoting the name service (@pxref{Services in the NSS
6416 configuration,,, libc, The GNU C Library Reference Manual}).
6418 Note that name services listed here must be visible to nscd. This is
6419 achieved by passing the @code{#:name-services} argument to
6420 @code{nscd-service} the list of packages providing the needed name
6421 services (@pxref{Base Services, @code{nscd-service}}).
6424 An action specified using the @code{lookup-specification} macro
6425 (@pxref{Actions in the NSS configuration,,, libc, The GNU C Library
6426 Reference Manual}). For example:
6429 (lookup-specification (unavailable => continue)
6430 (success => return))
6435 @node Initial RAM Disk
6436 @subsection Initial RAM Disk
6438 @cindex initial RAM disk (initrd)
6439 @cindex initrd (initial RAM disk)
6440 For bootstrapping purposes, the Linux-Libre kernel is passed an
6441 @dfn{initial RAM disk}, or @dfn{initrd}. An initrd contains a temporary
6442 root file system, as well as an initialization script. The latter is
6443 responsible for mounting the real root file system, and for loading any
6444 kernel modules that may be needed to achieve that.
6446 The @code{initrd} field of an @code{operating-system} declaration allows
6447 you to specify which initrd you would like to use. The @code{(gnu
6448 system linux-initrd)} module provides two ways to build an initrd: the
6449 high-level @code{base-initrd} procedure, and the low-level
6450 @code{expression->initrd} procedure.
6452 The @code{base-initrd} procedure is intended to cover most common uses.
6453 For example, if you want to add a bunch of kernel modules to be loaded
6454 at boot time, you can define the @code{initrd} field of the operating
6455 system declaration like this:
6458 (initrd (lambda (file-systems . rest)
6459 ;; Create a standard initrd that has modules "foo.ko"
6460 ;; and "bar.ko", as well as their dependencies, in
6461 ;; addition to the modules available by default.
6462 (apply base-initrd file-systems
6463 #:extra-modules '("foo" "bar")
6467 The @code{base-initrd} procedure also handles common use cases that
6468 involves using the system as a QEMU guest, or as a ``live'' system whose
6469 root file system is volatile.
6471 @deffn {Monadic Procedure} base-initrd @var{file-systems} @
6472 [#:qemu-networking? #f] [#:virtio? #f] [#:volatile-root? #f] @
6473 [#:extra-modules '()] [#:mapped-devices '()]
6474 Return a monadic derivation that builds a generic initrd. @var{file-systems} is
6475 a list of file-systems to be mounted by the initrd, possibly in addition to
6476 the root file system specified on the kernel command line via @code{--root}.
6477 @var{mapped-devices} is a list of device mappings to realize before
6478 @var{file-systems} are mounted (@pxref{Mapped Devices}).
6480 When @var{qemu-networking?} is true, set up networking with the standard QEMU
6481 parameters. When @var{virtio?} is true, load additional modules so the initrd can
6482 be used as a QEMU guest with para-virtualized I/O drivers.
6484 When @var{volatile-root?} is true, the root file system is writable but any changes
6487 The initrd is automatically populated with all the kernel modules necessary
6488 for @var{file-systems} and for the given options. However, additional kernel
6489 modules can be listed in @var{extra-modules}. They will be added to the initrd, and
6490 loaded at boot time in the order in which they appear.
6493 Needless to say, the initrds we produce and use embed a
6494 statically-linked Guile, and the initialization program is a Guile
6495 program. That gives a lot of flexibility. The
6496 @code{expression->initrd} procedure builds such an initrd, given the
6497 program to run in that initrd.
6499 @deffn {Monadic Procedure} expression->initrd @var{exp} @
6500 [#:guile %guile-static-stripped] [#:name "guile-initrd"] @
6502 Return a derivation that builds a Linux initrd (a gzipped cpio archive)
6503 containing @var{guile} and that evaluates @var{exp}, a G-expression,
6504 upon booting. All the derivations referenced by @var{exp} are
6505 automatically copied to the initrd.
6507 @var{modules} is a list of Guile module names to be embedded in the
6511 @node GRUB Configuration
6512 @subsection GRUB Configuration
6517 The operating system uses GNU@tie{}GRUB as its boot loader
6518 (@pxref{Overview, overview of GRUB,, grub, GNU GRUB Manual}). It is
6519 configured using @code{grub-configuration} declarations. This data type
6520 is exported by the @code{(gnu system grub)} module, and described below.
6522 @deftp {Data Type} grub-configuration
6523 The type of a GRUB configuration declaration.
6528 This is a string denoting the boot device. It must be a device name
6529 understood by the @command{grub-install} command, such as
6530 @code{/dev/sda} or @code{(hd0)} (@pxref{Invoking grub-install,,, grub,
6533 @item @code{menu-entries} (default: @code{()})
6534 A possibly empty list of @code{menu-entry} objects (see below), denoting
6535 entries to appear in the GRUB boot menu, in addition to the current
6536 system entry and the entry pointing to previous system generations.
6538 @item @code{default-entry} (default: @code{0})
6539 The index of the default boot menu entry. Index 0 is for the current
6542 @item @code{timeout} (default: @code{5})
6543 The number of seconds to wait for keyboard input before booting. Set to
6544 0 to boot immediately, and to -1 to wait indefinitely.
6546 @item @code{theme} (default: @var{%default-theme})
6547 The @code{grub-theme} object describing the theme to use.
6552 Should you want to list additional boot menu entries @i{via} the
6553 @code{menu-entries} field above, you will need to create them with the
6554 @code{menu-entry} form:
6556 @deftp {Data Type} menu-entry
6557 The type of an entry in the GRUB boot menu.
6562 The label to show in the menu---e.g., @code{"GNU"}.
6565 The Linux kernel to boot.
6567 @item @code{linux-arguments} (default: @code{()})
6568 The list of extra Linux kernel command-line arguments---e.g.,
6569 @code{("console=ttyS0")}.
6572 A G-Expression or string denoting the file name of the initial RAM disk
6573 to use (@pxref{G-Expressions}).
6578 @c FIXME: Write documentation once it's stable.
6579 Themes are created using the @code{grub-theme} form, which is not
6582 @defvr {Scheme Variable} %default-theme
6583 This is the default GRUB theme used by the operating system, with a
6584 fancy background image displaying the GNU and Guix logos.
6588 @node Invoking guix system
6589 @subsection Invoking @code{guix system}
6591 Once you have written an operating system declaration, as seen in the
6592 previous section, it can be @dfn{instantiated} using the @command{guix
6593 system} command. The synopsis is:
6596 guix system @var{options}@dots{} @var{action} @var{file}
6599 @var{file} must be the name of a file containing an
6600 @code{operating-system} declaration. @var{action} specifies how the
6601 operating system is instantiate. Currently the following values are
6606 Build the operating system described in @var{file}, activate it, and
6607 switch to it@footnote{This action is usable only on systems already
6610 This effects all the configuration specified in @var{file}: user
6611 accounts, system services, global package list, setuid programs, etc.
6613 It also adds a GRUB menu entry for the new OS configuration, and moves
6614 entries for older configurations to a submenu---unless
6615 @option{--no-grub} is passed.
6617 @c The paragraph below refers to the problem discussed at
6618 @c <http://lists.gnu.org/archive/html/guix-devel/2014-08/msg00057.html>.
6619 It is highly recommended to run @command{guix pull} once before you run
6620 @command{guix system reconfigure} for the first time (@pxref{Invoking
6621 guix pull}). Failing to do that you would see an older version of Guix
6622 once @command{reconfigure} has completed.
6625 Build the operating system's derivation, which includes all the
6626 configuration files and programs needed to boot and run the system.
6627 This action does not actually install anything.
6630 Populate the given directory with all the files necessary to run the
6631 operating system specified in @var{file}. This is useful for first-time
6632 installations of GuixSD. For instance:
6635 guix system init my-os-config.scm /mnt
6638 copies to @file{/mnt} all the store items required by the configuration
6639 specified in @file{my-os-config.scm}. This includes configuration
6640 files, packages, and so on. It also creates other essential files
6641 needed for the system to operate correctly---e.g., the @file{/etc},
6642 @file{/var}, and @file{/run} directories, and the @file{/bin/sh} file.
6644 This command also installs GRUB on the device specified in
6645 @file{my-os-config}, unless the @option{--no-grub} option was passed.
6648 @cindex virtual machine
6650 Build a virtual machine that contain the operating system declared in
6651 @var{file}, and return a script to run that virtual machine (VM).
6652 Arguments given to the script are passed as is to QEMU.
6654 The VM shares its store with the host system.
6656 Additional file systems can be shared between the host and the VM using
6657 the @code{--share} and @code{--expose} command-line options: the former
6658 specifies a directory to be shared with write access, while the latter
6659 provides read-only access to the shared directory.
6661 The example below creates a VM in which the user's home directory is
6662 accessible read-only, and where the @file{/exchange} directory is a
6663 read-write mapping of the host's @file{$HOME/tmp}:
6666 guix system vm my-config.scm \
6667 --expose=$HOME --share=$HOME/tmp=/exchange
6670 On GNU/Linux, the default is to boot directly to the kernel; this has
6671 the advantage of requiring only a very tiny root disk image since the
6672 host's store can then be mounted.
6674 The @code{--full-boot} option forces a complete boot sequence, starting
6675 with the bootloader. This requires more disk space since a root image
6676 containing at least the kernel, initrd, and bootloader data files must
6677 be created. The @code{--image-size} option can be used to specify the
6682 Return a virtual machine or disk image of the operating system declared
6683 in @var{file} that stands alone. Use the @option{--image-size} option
6684 to specify the size of the image.
6686 When using @code{vm-image}, the returned image is in qcow2 format, which
6687 the QEMU emulator can efficiently use.
6689 When using @code{disk-image}, a raw disk image is produced; it can be
6690 copied as is to a USB stick, for instance. Assuming @code{/dev/sdc} is
6691 the device corresponding to a USB stick, one can copy the image on it
6692 using the following command:
6695 # dd if=$(guix system disk-image my-os.scm) of=/dev/sdc
6700 @var{options} can contain any of the common build options provided by
6701 @command{guix build} (@pxref{Invoking guix build}). In addition,
6702 @var{options} can contain one of the following:
6705 @item --system=@var{system}
6706 @itemx -s @var{system}
6707 Attempt to build for @var{system} instead of the host's system type.
6708 This works as per @command{guix build} (@pxref{Invoking guix build}).
6710 @item --image-size=@var{size}
6711 For the @code{vm-image} and @code{disk-image} actions, create an image
6712 of the given @var{size}. @var{size} may be a number of bytes, or it may
6713 include a unit as a suffix (@pxref{Block size, size specifications,,
6714 coreutils, GNU Coreutils}).
6716 @item --on-error=@var{strategy}
6717 Apply @var{strategy} when an error occurs when reading @var{file}.
6718 @var{strategy} may be one of the following:
6721 @item nothing-special
6722 Report the error concisely and exit. This is the default strategy.
6725 Likewise, but also display a backtrace.
6728 Report the error and enter Guile's debugger. From there, you can run
6729 commands such as @code{,bt} to get a backtrace, @code{,locals} to
6730 display local variable values, and more generally inspect the program's
6731 state. @xref{Debug Commands,,, guile, GNU Guile Reference Manual}, for
6732 a list of available debugging commands.
6736 Note that all the actions above, except @code{build} and @code{init},
6737 rely on KVM support in the Linux-Libre kernel. Specifically, the
6738 machine should have hardware virtualization support, the corresponding
6739 KVM kernel module should be loaded, and the @file{/dev/kvm} device node
6740 must exist and be readable and writable by the user and by the daemon's
6743 @node Defining Services
6744 @subsection Defining Services
6746 The @code{(gnu services @dots{})} modules define several procedures that allow
6747 users to declare the operating system's services (@pxref{Using the
6748 Configuration System}). These procedures are @emph{monadic
6749 procedures}---i.e., procedures that return a monadic value in the store
6750 monad (@pxref{The Store Monad}). For examples of such procedures,
6753 @cindex service definition
6754 The monadic value returned by those procedures is a @dfn{service
6755 definition}---a structure as returned by the @code{service} form.
6756 Service definitions specifies the inputs the service depends on, and an
6757 expression to start and stop the service. Behind the scenes, service
6758 definitions are ``translated'' into the form suitable for the
6759 configuration file of dmd, the init system (@pxref{Services,,, dmd, GNU
6762 As an example, here is what the @code{nscd-service} procedure looks
6766 (define (nscd-service)
6767 (with-monad %store-monad
6769 (documentation "Run libc's name service cache daemon.")
6772 (use-modules (guix build utils))
6773 (mkdir-p "/var/run/nscd")))
6774 (start #~(make-forkexec-constructor
6775 (string-append #$glibc "/sbin/nscd")
6776 "-f" "/dev/null" "--foreground"))
6777 (stop #~(make-kill-destructor))
6782 The @code{activate}, @code{start}, and @code{stop} fields are G-expressions
6783 (@pxref{G-Expressions}). The @code{activate} field contains a script to
6784 run at ``activation'' time; it makes sure that the @file{/var/run/nscd}
6785 directory exists before @command{nscd} is started.
6787 The @code{start} and @code{stop} fields refer to dmd's facilities to
6788 start and stop processes (@pxref{Service De- and Constructors,,, dmd,
6789 GNU dmd Manual}). The @code{provision} field specifies the name under
6790 which this service is known to dmd, and @code{documentation} specifies
6791 on-line documentation. Thus, the commands @command{deco start ncsd},
6792 @command{deco stop nscd}, and @command{deco doc nscd} will do what you
6793 would expect (@pxref{Invoking deco,,, dmd, GNU dmd Manual}).
6796 @node Installing Debugging Files
6797 @section Installing Debugging Files
6799 @cindex debugging files
6800 Program binaries, as produced by the GCC compilers for instance, are
6801 typically written in the ELF format, with a section containing
6802 @dfn{debugging information}. Debugging information is what allows the
6803 debugger, GDB, to map binary code to source code; it is required to
6804 debug a compiled program in good conditions.
6806 The problem with debugging information is that is takes up a fair amount
6807 of disk space. For example, debugging information for the GNU C Library
6808 weighs in at more than 60 MiB. Thus, as a user, keeping all the
6809 debugging info of all the installed programs is usually not an option.
6810 Yet, space savings should not come at the cost of an impediment to
6811 debugging---especially in the GNU system, which should make it easier
6812 for users to exert their computing freedom (@pxref{GNU Distribution}).
6814 Thankfully, the GNU Binary Utilities (Binutils) and GDB provide a
6815 mechanism that allows users to get the best of both worlds: debugging
6816 information can be stripped from the binaries and stored in separate
6817 files. GDB is then able to load debugging information from those files,
6818 when they are available (@pxref{Separate Debug Files,,, gdb, Debugging
6821 The GNU distribution takes advantage of this by storing debugging
6822 information in the @code{lib/debug} sub-directory of a separate package
6823 output unimaginatively called @code{debug} (@pxref{Packages with
6824 Multiple Outputs}). Users can choose to install the @code{debug} output
6825 of a package when they need it. For instance, the following command
6826 installs the debugging information for the GNU C Library and for GNU
6830 guix package -i glibc:debug guile:debug
6833 GDB must then be told to look for debug files in the user's profile, by
6834 setting the @code{debug-file-directory} variable (consider setting it
6835 from the @file{~/.gdbinit} file, @pxref{Startup,,, gdb, Debugging with
6839 (gdb) set debug-file-directory ~/.guix-profile/lib/debug
6842 From there on, GDB will pick up debugging information from the
6843 @code{.debug} files under @file{~/.guix-profile/lib/debug}.
6845 In addition, you will most likely want GDB to be able to show the source
6846 code being debugged. To do that, you will have to unpack the source
6847 code of the package of interest (obtained with @code{guix build
6848 --source}, @pxref{Invoking guix build}), and to point GDB to that source
6849 directory using the @code{directory} command (@pxref{Source Path,
6850 @code{directory},, gdb, Debugging with GDB}).
6852 @c XXX: keep me up-to-date
6853 The @code{debug} output mechanism in Guix is implemented by the
6854 @code{gnu-build-system} (@pxref{Build Systems}). Currently, it is
6855 opt-in---debugging information is available only for those packages
6856 whose definition explicitly declares a @code{debug} output. This may be
6857 changed to opt-out in the future, if our build farm servers can handle
6858 the load. To check whether a package has a @code{debug} output, use
6859 @command{guix package --list-available} (@pxref{Invoking guix package}).
6862 @node Security Updates
6863 @section Security Updates
6866 As of version @value{VERSION}, the feature described in this section is
6870 @cindex security updates
6871 Occasionally, important security vulnerabilities are discovered in core
6872 software packages and must be patched. Guix follows a functional
6873 package management discipline (@pxref{Introduction}), which implies
6874 that, when a package is changed, @emph{every package that depends on it}
6875 must be rebuilt. This can significantly slow down the deployment of
6876 fixes in core packages such as libc or Bash, since basically the whole
6877 distribution would need to be rebuilt. Using pre-built binaries helps
6878 (@pxref{Substitutes}), but deployment may still take more time than
6882 To address that, Guix implements @dfn{grafts}, a mechanism that allows
6883 for fast deployment of critical updates without the costs associated
6884 with a whole-distribution rebuild. The idea is to rebuild only the
6885 package that needs to be patched, and then to ``graft'' it onto packages
6886 explicitly installed by the user and that were previously referring to
6887 the original package. The cost of grafting is typically very low, and
6888 order of magnitudes lower than a full rebuild of the dependency chain.
6890 @cindex replacements of packages, for grafts
6891 For instance, suppose a security update needs to be applied to Bash.
6892 Guix developers will provide a package definition for the ``fixed''
6893 Bash, say @var{bash-fixed}, in the usual way (@pxref{Defining
6894 Packages}). Then, the original package definition is augmented with a
6895 @code{replacement} field pointing to the package containing the bug fix:
6902 (replacement bash-fixed)))
6905 From there on, any package depending directly or indirectly on Bash that
6906 is installed will automatically be ``rewritten'' to refer to
6907 @var{bash-fixed} instead of @var{bash}. This grafting process takes
6908 time proportional to the size of the package, but expect less than a
6909 minute for an ``average'' package on a recent machine.
6911 Currently, the graft and the package it replaces (@var{bash-fixed} and
6912 @var{bash} in the example above) must have the exact same @code{name}
6913 and @code{version} fields. This restriction mostly comes from the fact
6914 that grafting works by patching files, including binary files, directly.
6915 Other restrictions may apply: for instance, when adding a graft to a
6916 package providing a shared library, the original shared library and its
6917 replacement must have the same @code{SONAME} and be binary-compatible.
6920 @node Package Modules
6921 @section Package Modules
6923 From a programming viewpoint, the package definitions of the
6924 GNU distribution are provided by Guile modules in the @code{(gnu packages
6925 @dots{})} name space@footnote{Note that packages under the @code{(gnu
6926 packages @dots{})} module name space are not necessarily ``GNU
6927 packages''. This module naming scheme follows the usual Guile module
6928 naming convention: @code{gnu} means that these modules are distributed
6929 as part of the GNU system, and @code{packages} identifies modules that
6930 define packages.} (@pxref{Modules, Guile modules,, guile, GNU Guile
6931 Reference Manual}). For instance, the @code{(gnu packages emacs)}
6932 module exports a variable named @code{emacs}, which is bound to a
6933 @code{<package>} object (@pxref{Defining Packages}).
6935 The @code{(gnu packages @dots{})} module name space is
6936 automatically scanned for packages by the command-line tools. For
6937 instance, when running @code{guix package -i emacs}, all the @code{(gnu
6938 packages @dots{})} modules are scanned until one that exports a package
6939 object whose name is @code{emacs} is found. This package search
6940 facility is implemented in the @code{(gnu packages)} module.
6942 @cindex customization, of packages
6943 @cindex package module search path
6944 Users can store package definitions in modules with different
6945 names---e.g., @code{(my-packages emacs)}@footnote{Note that the file
6946 name and module name must match. For instance, the @code{(my-packages
6947 emacs)} module must be stored in a @file{my-packages/emacs.scm} file
6948 relative to the load path specified with @option{--load-path} or
6949 @code{GUIX_PACKAGE_PATH}. @xref{Modules and the File System,,,
6950 guile, GNU Guile Reference Manual}, for details.}. These package definitions
6951 will not be visible by default. Thus, users can invoke commands such as
6952 @command{guix package} and @command{guix build} have to be used with the
6953 @code{-e} option so that they know where to find the package. Better
6954 yet, they can use the
6955 @code{-L} option of these commands to make those modules visible
6956 (@pxref{Invoking guix build, @code{--load-path}}), or define the
6957 @code{GUIX_PACKAGE_PATH} environment variable. This environment
6958 variable makes it easy to extend or customize the distribution and is
6959 honored by all the user interfaces.
6961 @defvr {Environment Variable} GUIX_PACKAGE_PATH
6962 This is a colon-separated list of directories to search for package
6963 modules. Directories listed in this variable take precedence over the
6964 distribution's own modules.
6967 The distribution is fully @dfn{bootstrapped} and @dfn{self-contained}:
6968 each package is built based solely on other packages in the
6969 distribution. The root of this dependency graph is a small set of
6970 @dfn{bootstrap binaries}, provided by the @code{(gnu packages
6971 bootstrap)} module. For more information on bootstrapping,
6972 @pxref{Bootstrapping}.
6974 @node Packaging Guidelines
6975 @section Packaging Guidelines
6977 The GNU distribution is nascent and may well lack some of your favorite
6978 packages. This section describes how you can help make the distribution
6979 grow. @xref{Contributing}, for additional information on how you can
6982 Free software packages are usually distributed in the form of
6983 @dfn{source code tarballs}---typically @file{tar.gz} files that contain
6984 all the source files. Adding a package to the distribution means
6985 essentially two things: adding a @dfn{recipe} that describes how to
6986 build the package, including a list of other packages required to build
6987 it, and adding @dfn{package meta-data} along with that recipe, such as a
6988 description and licensing information.
6990 In Guix all this information is embodied in @dfn{package definitions}.
6991 Package definitions provide a high-level view of the package. They are
6992 written using the syntax of the Scheme programming language; in fact,
6993 for each package we define a variable bound to the package definition,
6994 and export that variable from a module (@pxref{Package Modules}).
6995 However, in-depth Scheme knowledge is @emph{not} a prerequisite for
6996 creating packages. For more information on package definitions,
6997 @pxref{Defining Packages}.
6999 Once a package definition is in place, stored in a file in the Guix
7000 source tree, it can be tested using the @command{guix build} command
7001 (@pxref{Invoking guix build}). For example, assuming the new package is
7002 called @code{gnew}, you may run this command from the Guix build tree
7003 (@pxref{Running Guix Before It Is Installed}):
7006 ./pre-inst-env guix build gnew --keep-failed
7009 Using @code{--keep-failed} makes it easier to debug build failures since
7010 it provides access to the failed build tree. Another useful
7011 command-line option when debugging is @code{--log-file}, to access the
7014 If the package is unknown to the @command{guix} command, it may be that
7015 the source file contains a syntax error, or lacks a @code{define-public}
7016 clause to export the package variable. To figure it out, you may load
7017 the module from Guile to get more information about the actual error:
7020 ./pre-inst-env guile -c '(use-modules (gnu packages gnew))'
7023 Once your package builds correctly, please send us a patch
7024 (@pxref{Contributing}). Well, if you need help, we will be happy to
7025 help you too. Once the patch is committed in the Guix repository, the
7026 new package automatically gets built on the supported platforms by
7027 @url{http://hydra.gnu.org/jobset/gnu/master, our continuous integration
7031 Users can obtain the new package definition simply by running
7032 @command{guix pull} (@pxref{Invoking guix pull}). When
7033 @code{hydra.gnu.org} is done building the package, installing the
7034 package automatically downloads binaries from there
7035 (@pxref{Substitutes}). The only place where human intervention is
7036 needed is to review and apply the patch.
7040 * Software Freedom:: What may go into the distribution.
7041 * Package Naming:: What's in a name?
7042 * Version Numbers:: When the name is not enough.
7043 * Python Modules:: Taming the snake.
7044 * Perl Modules:: Little pearls.
7045 * Fonts:: Fond of fonts.
7048 @node Software Freedom
7049 @subsection Software Freedom
7051 @c Adapted from http://www.gnu.org/philosophy/philosophy.html.
7053 The GNU operating system has been developed so that users can have
7054 freedom in their computing. GNU is @dfn{free software}, meaning that
7055 users have the @url{http://www.gnu.org/philosophy/free-sw.html,four
7056 essential freedoms}: to run the program, to study and change the program
7057 in source code form, to redistribute exact copies, and to distribute
7058 modified versions. Packages found in the GNU distribution provide only
7059 software that conveys these four freedoms.
7061 In addition, the GNU distribution follow the
7062 @url{http://www.gnu.org/distros/free-system-distribution-guidelines.html,free
7063 software distribution guidelines}. Among other things, these guidelines
7064 reject non-free firmware, recommendations of non-free software, and
7065 discuss ways to deal with trademarks and patents.
7067 Some packages contain a small and optional subset that violates the
7068 above guidelines, for instance because this subset is itself non-free
7069 code. When that happens, the offending items are removed with
7070 appropriate patches or code snippets in the package definition's
7071 @code{origin} form (@pxref{Defining Packages}). That way, @code{guix
7072 build --source} returns the ``freed'' source rather than the unmodified
7076 @node Package Naming
7077 @subsection Package Naming
7079 A package has actually two names associated with it:
7080 First, there is the name of the @emph{Scheme variable}, the one following
7081 @code{define-public}. By this name, the package can be made known in the
7082 Scheme code, for instance as input to another package. Second, there is
7083 the string in the @code{name} field of a package definition. This name
7084 is used by package management commands such as
7085 @command{guix package} and @command{guix build}.
7087 Both are usually the same and correspond to the lowercase conversion of
7088 the project name chosen upstream, with underscores replaced with
7089 hyphens. For instance, GNUnet is available as @code{gnunet}, and
7090 SDL_net as @code{sdl-net}.
7092 We do not add @code{lib} prefixes for library packages, unless these are
7093 already part of the official project name. But @pxref{Python
7094 Modules} and @ref{Perl Modules} for special rules concerning modules for
7095 the Python and Perl languages.
7097 Font package names are handled differently, @pxref{Fonts}.
7100 @node Version Numbers
7101 @subsection Version Numbers
7103 We usually package only the latest version of a given free software
7104 project. But sometimes, for instance for incompatible library versions,
7105 two (or more) versions of the same package are needed. These require
7106 different Scheme variable names. We use the name as defined
7107 in @ref{Package Naming}
7108 for the most recent version; previous versions use the same name, suffixed
7109 by @code{-} and the smallest prefix of the version number that may
7110 distinguish the two versions.
7112 The name inside the package definition is the same for all versions of a
7113 package and does not contain any version number.
7115 For instance, the versions 2.24.20 and 3.9.12 of GTK+ may be packaged as follows:
7123 (define-public gtk+-2
7129 If we also wanted GTK+ 3.8.2, this would be packaged as
7131 (define-public gtk+-3.8
7139 @node Python Modules
7140 @subsection Python Modules
7142 We currently package Python 2 and Python 3, under the Scheme variable names
7143 @code{python-2} and @code{python} as explained in @ref{Version Numbers}.
7144 To avoid confusion and naming clashes with other programming languages, it
7145 seems desirable that the name of a package for a Python module contains
7146 the word @code{python}.
7148 Some modules are compatible with only one version of Python, others with both.
7149 If the package Foo compiles only with Python 3, we name it
7150 @code{python-foo}; if it compiles only with Python 2, we name it
7151 @code{python2-foo}. If it is compatible with both versions, we create two
7152 packages with the corresponding names.
7154 If a project already contains the word @code{python}, we drop this;
7155 for instance, the module python-dateutil is packaged under the names
7156 @code{python-dateutil} and @code{python2-dateutil}.
7160 @subsection Perl Modules
7162 Perl programs standing for themselves are named as any other package,
7163 using the lowercase upstream name.
7164 For Perl packages containing a single class, we use the lowercase class name,
7165 replace all occurrences of @code{::} by dashes and prepend the prefix
7167 So the class @code{XML::Parser} becomes @code{perl-xml-parser}.
7168 Modules containing several classes keep their lowercase upstream name and
7169 are also prepended by @code{perl-}. Such modules tend to have the word
7170 @code{perl} somewhere in their name, which gets dropped in favor of the
7171 prefix. For instance, @code{libwww-perl} becomes @code{perl-libwww}.
7177 For fonts that are in general not installed by a user for typesetting
7178 purposes, or that are distributed as part of a larger software package,
7179 we rely on the general packaging rules for software; for instance, this
7180 applies to the fonts delivered as part of the X.Org system or fonts that
7181 are part of TeX Live.
7183 To make it easier for a user to search for fonts, names for other packages
7184 containing only fonts are constructed as follows, independently of the
7185 upstream package name.
7187 The name of a package containing only one font family starts with
7188 @code{font-}; it is followed by the foundry name and a dash @code{-}
7189 if the foundry is known, and the font family name, in which spaces are
7190 replaced by dashes (and as usual, all upper case letters are transformed
7192 For example, the Gentium font family by SIL is packaged under the name
7193 @code{font-sil-gentium}.
7195 For a package containing several font families, the name of the collection
7196 is used in the place of the font family name.
7197 For instance, the Liberation fonts consist of three families,
7198 Liberation Sans, Liberation Serif and Liberation Mono.
7199 These could be packaged separately under the names
7200 @code{font-liberation-sans} and so on; but as they are distributed together
7201 under a common name, we prefer to package them together as
7202 @code{font-liberation}.
7204 In the case where several formats of the same font family or font collection
7205 are packaged separately, a short form of the format, prepended by a dash,
7206 is added to the package name. We use @code{-ttf} for TrueType fonts,
7207 @code{-otf} for OpenType fonts and @code{-type1} for PostScript Type 1
7213 @section Bootstrapping
7215 @c Adapted from the ELS 2013 paper.
7217 @cindex bootstrapping
7219 Bootstrapping in our context refers to how the distribution gets built
7220 ``from nothing''. Remember that the build environment of a derivation
7221 contains nothing but its declared inputs (@pxref{Introduction}). So
7222 there's an obvious chicken-and-egg problem: how does the first package
7223 get built? How does the first compiler get compiled? Note that this is
7224 a question of interest only to the curious hacker, not to the regular
7225 user, so you can shamelessly skip this section if you consider yourself
7228 @cindex bootstrap binaries
7229 The GNU system is primarily made of C code, with libc at its core. The
7230 GNU build system itself assumes the availability of a Bourne shell and
7231 command-line tools provided by GNU Coreutils, Awk, Findutils, `sed', and
7232 `grep'. Furthermore, build programs---programs that run
7233 @code{./configure}, @code{make}, etc.---are written in Guile Scheme
7234 (@pxref{Derivations}). Consequently, to be able to build anything at
7235 all, from scratch, Guix relies on pre-built binaries of Guile, GCC,
7236 Binutils, libc, and the other packages mentioned above---the
7237 @dfn{bootstrap binaries}.
7239 These bootstrap binaries are ``taken for granted'', though we can also
7240 re-create them if needed (more on that later).
7242 @unnumberedsubsec Preparing to Use the Bootstrap Binaries
7244 @c As of Emacs 24.3, Info-mode displays the image, but since it's a
7245 @c large image, it's hard to scroll. Oh well.
7246 @image{images/bootstrap-graph,6in,,Dependency graph of the early bootstrap derivations}
7248 The figure above shows the very beginning of the dependency graph of the
7249 distribution, corresponding to the package definitions of the @code{(gnu
7250 packages bootstrap)} module. At this level of detail, things are
7251 slightly complex. First, Guile itself consists of an ELF executable,
7252 along with many source and compiled Scheme files that are dynamically
7253 loaded when it runs. This gets stored in the @file{guile-2.0.7.tar.xz}
7254 tarball shown in this graph. This tarball is part of Guix's ``source''
7255 distribution, and gets inserted into the store with @code{add-to-store}
7256 (@pxref{The Store}).
7258 But how do we write a derivation that unpacks this tarball and adds it
7259 to the store? To solve this problem, the @code{guile-bootstrap-2.0.drv}
7260 derivation---the first one that gets built---uses @code{bash} as its
7261 builder, which runs @code{build-bootstrap-guile.sh}, which in turn calls
7262 @code{tar} to unpack the tarball. Thus, @file{bash}, @file{tar},
7263 @file{xz}, and @file{mkdir} are statically-linked binaries, also part of
7264 the Guix source distribution, whose sole purpose is to allow the Guile
7265 tarball to be unpacked.
7267 Once @code{guile-bootstrap-2.0.drv} is built, we have a functioning
7268 Guile that can be used to run subsequent build programs. Its first task
7269 is to download tarballs containing the other pre-built binaries---this
7270 is what the @code{.tar.xz.drv} derivations do. Guix modules such as
7271 @code{ftp-client.scm} are used for this purpose. The
7272 @code{module-import.drv} derivations import those modules in a directory
7273 in the store, using the original layout. The
7274 @code{module-import-compiled.drv} derivations compile those modules, and
7275 write them in an output directory with the right layout. This
7276 corresponds to the @code{#:modules} argument of
7277 @code{build-expression->derivation} (@pxref{Derivations}).
7279 Finally, the various tarballs are unpacked by the
7280 derivations @code{gcc-bootstrap-0.drv}, @code{glibc-bootstrap-0.drv},
7281 etc., at which point we have a working C tool chain.
7284 @unnumberedsubsec Building the Build Tools
7286 @c TODO: Add a package-level dependency graph generated from (gnu
7289 Bootstrapping is complete when we have a full tool chain that does not
7290 depend on the pre-built bootstrap tools discussed above. This
7291 no-dependency requirement is verified by checking whether the files of
7292 the final tool chain contain references to the @file{/gnu/store}
7293 directories of the bootstrap inputs. The process that leads to this
7294 ``final'' tool chain is described by the package definitions found in
7295 the @code{(gnu packages commencement)} module.
7297 @c See <http://lists.gnu.org/archive/html/gnu-system-discuss/2012-10/msg00000.html>.
7298 The first tool that gets built with the bootstrap binaries is
7299 GNU Make, which is a prerequisite for all the following packages.
7300 From there Findutils and Diffutils get built.
7302 Then come the first-stage Binutils and GCC, built as pseudo cross
7303 tools---i.e., with @code{--target} equal to @code{--host}. They are
7304 used to build libc. Thanks to this cross-build trick, this libc is
7305 guaranteed not to hold any reference to the initial tool chain.
7307 From there the final Binutils and GCC are built. GCC uses @code{ld}
7308 from the final Binutils, and links programs against the just-built libc.
7309 This tool chain is used to build the other packages used by Guix and by
7310 the GNU Build System: Guile, Bash, Coreutils, etc.
7312 And voilà! At this point we have the complete set of build tools that
7313 the GNU Build System expects. These are in the @code{%final-inputs}
7314 variable of the @code{(gnu packages commencement)} module, and are
7315 implicitly used by any package that uses @code{gnu-build-system}
7316 (@pxref{Build Systems, @code{gnu-build-system}}).
7319 @unnumberedsubsec Building the Bootstrap Binaries
7321 Because the final tool chain does not depend on the bootstrap binaries,
7322 those rarely need to be updated. Nevertheless, it is useful to have an
7323 automated way to produce them, should an update occur, and this is what
7324 the @code{(gnu packages make-bootstrap)} module provides.
7326 The following command builds the tarballs containing the bootstrap
7327 binaries (Guile, Binutils, GCC, libc, and a tarball containing a mixture
7328 of Coreutils and other basic command-line tools):
7331 guix build bootstrap-tarballs
7334 The generated tarballs are those that should be referred to in the
7335 @code{(gnu packages bootstrap)} module mentioned at the beginning of
7338 Still here? Then perhaps by now you've started to wonder: when do we
7339 reach a fixed point? That is an interesting question! The answer is
7340 unknown, but if you would like to investigate further (and have
7341 significant computational and storage resources to do so), then let us
7345 @section Porting to a New Platform
7347 As discussed above, the GNU distribution is self-contained, and
7348 self-containment is achieved by relying on pre-built ``bootstrap
7349 binaries'' (@pxref{Bootstrapping}). These binaries are specific to an
7350 operating system kernel, CPU architecture, and application binary
7351 interface (ABI). Thus, to port the distribution to a platform that is
7352 not yet supported, one must build those bootstrap binaries, and update
7353 the @code{(gnu packages bootstrap)} module to use them on that platform.
7355 Fortunately, Guix can @emph{cross compile} those bootstrap binaries.
7356 When everything goes well, and assuming the GNU tool chain supports the
7357 target platform, this can be as simple as running a command like this
7361 guix build --target=armv5tel-linux-gnueabi bootstrap-tarballs
7364 For this to work, the @code{glibc-dynamic-linker} procedure in
7365 @code{(gnu packages bootstrap)} must be augmented to return the right
7366 file name for libc's dynamic linker on that platform; likewise,
7367 @code{system->linux-architecture} in @code{(gnu packages linux)} must be
7368 taught about the new platform.
7370 Once these are built, the @code{(gnu packages bootstrap)} module needs
7371 to be updated to refer to these binaries on the target platform. That
7372 is, the hashes and URLs of the bootstrap tarballs for the new platform
7373 must be added alongside those of the currently supported platforms. The
7374 bootstrap Guile tarball is treated specially: it is expected to be
7375 available locally, and @file{gnu-system.am} has rules do download it for
7376 the supported architectures; a rule for the new platform must be added
7379 In practice, there may be some complications. First, it may be that the
7380 extended GNU triplet that specifies an ABI (like the @code{eabi} suffix
7381 above) is not recognized by all the GNU tools. Typically, glibc
7382 recognizes some of these, whereas GCC uses an extra @code{--with-abi}
7383 configure flag (see @code{gcc.scm} for examples of how to handle this).
7384 Second, some of the required packages could fail to build for that
7385 platform. Lastly, the generated binaries could be broken for some
7388 @c *********************************************************************
7389 @include contributing.texi
7391 @c *********************************************************************
7392 @node Acknowledgments
7393 @chapter Acknowledgments
7395 Guix is based on the Nix package manager, which was designed and
7396 implemented by Eelco Dolstra, with contributions from other people (see
7397 the @file{nix/AUTHORS} file in Guix.) Nix pioneered functional package
7398 management, and promoted unprecedented features, such as transactional
7399 package upgrades and rollbacks, per-user profiles, and referentially
7400 transparent build processes. Without this work, Guix would not exist.
7402 The Nix-based software distributions, Nixpkgs and NixOS, have also been
7403 an inspiration for Guix.
7405 GNU@tie{}Guix itself is a collective work with contributions from a
7406 number of people. See the @file{AUTHORS} file in Guix for more
7407 information on these fine people. The @file{THANKS} file lists people
7408 who have helped by reporting bugs, taking care of the infrastructure,
7409 providing artwork and themes, making suggestions, and more---thank you!
7412 @c *********************************************************************
7413 @node GNU Free Documentation License
7414 @appendix GNU Free Documentation License
7416 @include fdl-1.3.texi
7418 @c *********************************************************************
7420 @unnumbered Concept Index
7423 @node Programming Index
7424 @unnumbered Programming Index
7432 @c ispell-local-dictionary: "american";