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 The GNU Guix Developers
51 @vskip 0pt plus 1filll
52 Edition @value{EDITION} @*
60 @c *********************************************************************
64 This document describes GNU Guix version @value{VERSION}, a functional
65 package management tool written for the GNU system.
68 * Introduction:: What is Guix about?
69 * Installation:: Installing Guix.
70 * Package Management:: Package installation, upgrade, etc.
71 * Emacs Interface:: Using Guix from Emacs.
72 * Programming Interface:: Using Guix in Scheme.
73 * Utilities:: Package management commands.
74 * GNU Distribution:: Software for your friendly GNU system.
75 * Contributing:: Your help needed!
77 * Acknowledgments:: Thanks!
78 * GNU Free Documentation License:: The license of this manual.
79 * Concept Index:: Concepts.
80 * Programming Index:: Data types, functions, and variables.
83 --- The Detailed Node Listing ---
87 * Binary Installation:: Getting Guix running in no time!
88 * Requirements:: Software needed to build and run Guix.
89 * Running the Test Suite:: Testing Guix.
90 * Setting Up the Daemon:: Preparing the build daemon's environment.
91 * Invoking guix-daemon:: Running the build daemon.
92 * Application Setup:: Application-specific setup.
96 * Build Environment Setup:: Preparing the isolated build environment.
97 * Daemon Offload Setup:: Offloading builds to remote machines.
101 * Features:: How Guix will make your life brighter.
102 * Invoking guix package:: Package installation, removal, etc.
103 * Substitutes:: Downloading pre-built binaries.
104 * Packages with Multiple Outputs:: Single source package, multiple outputs.
105 * Invoking guix gc:: Running the garbage collector.
106 * Invoking guix pull:: Fetching the latest Guix and distribution.
107 * Invoking guix archive:: Exporting and importing store files.
111 * Initial Setup: Emacs Initial Setup. Preparing @file{~/.emacs}.
112 * Package Management: Emacs Package Management. Managing packages and generations.
113 * Popup Interface: Emacs Popup Interface. Magit-like interface for guix commands.
114 * Prettify Mode: Emacs Prettify. Abbreviating @file{/gnu/store/@dots{}} file names.
115 * Build Log Mode: Emacs Build Log. Highlighting Guix build logs.
116 * Completions: Emacs Completions. Completing @command{guix} shell command.
117 * Development: Emacs Development. Tools for Guix developers.
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.
146 * Invoking guix challenge:: Challenging substitute servers.
147 * Invoking guix container:: Process isolation.
151 * System Installation:: Installing the whole operating system.
152 * System Configuration:: Configuring the operating system.
153 * Installing Debugging Files:: Feeding the debugger.
154 * Security Updates:: Deploying security fixes quickly.
155 * Package Modules:: Packages from the programmer's viewpoint.
156 * Packaging Guidelines:: Growing the distribution.
157 * Bootstrapping:: GNU/Linux built from scratch.
158 * Porting:: Targeting another platform or kernel.
162 * Using the Configuration System:: Customizing your GNU system.
163 * operating-system Reference:: Detail of operating-system declarations.
164 * File Systems:: Configuring file system mounts.
165 * Mapped Devices:: Block device extra processing.
166 * User Accounts:: Specifying user accounts.
167 * Locales:: Language and cultural convention settings.
168 * Services:: Specifying system services.
169 * Setuid Programs:: Programs running with root privileges.
170 * X.509 Certificates:: Authenticating HTTPS servers.
171 * Name Service Switch:: Configuring libc's name service switch.
172 * Initial RAM Disk:: Linux-Libre bootstrapping.
173 * GRUB Configuration:: Configuring the boot loader.
174 * Invoking guix system:: Instantiating a system configuration.
175 * Defining Services:: Adding new service definitions.
179 * Base Services:: Essential system services.
180 * Networking Services:: Network setup, SSH daemon, etc.
181 * X Window:: Graphical display.
182 * Desktop Services:: D-Bus and desktop services.
183 * Database Services:: SQL databases.
184 * Mail Services:: IMAP, POP3, SMTP, and all that.
185 * Web Services:: Web servers.
186 * Various Services:: Other services.
190 * Service Composition:: The model for composing services.
191 * Service Types and Services:: Types and services.
192 * Service Reference:: API reference.
193 * dmd Services:: A particular type of service.
197 * Software Freedom:: What may go into the distribution.
198 * Package Naming:: What's in a name?
199 * Version Numbers:: When the name is not enough.
200 * Synopses and Descriptions:: Helping users find the right package.
201 * Python Modules:: Taming the snake.
202 * Perl Modules:: Little pearls.
203 * Fonts:: Fond of fonts.
207 * Building from Git:: The latest and greatest.
208 * Running Guix Before It Is Installed:: Hacker tricks.
209 * The Perfect Setup:: The right tools.
210 * Coding Style:: Hygiene of the contributor.
211 * Submitting Patches:: Share your work.
215 * Programming Paradigm:: How to compose your elements.
216 * Modules:: Where to store your code?
217 * Data Types and Pattern Matching:: Implementing data structures.
218 * Formatting Code:: Writing conventions.
223 @c *********************************************************************
225 @chapter Introduction
227 GNU Guix@footnote{``Guix'' is pronounced like ``geeks'', or ``ɡiːks''
228 using the international phonetic alphabet (IPA).} is a functional
229 package management tool for the GNU system. Package management consists
230 of all activities that relate to building packages from sources,
231 honoring their build-time and run-time dependencies,
232 installing packages in user environments, upgrading installed packages
233 to new versions or rolling back to a previous set, removing unused
234 software packages, etc.
236 @cindex functional package management
237 The term @dfn{functional} refers to a specific package management
238 discipline pioneered by Nix (@pxref{Acknowledgments}).
239 In Guix, the package build and installation process is seen
240 as a function, in the mathematical sense. That function takes inputs,
241 such as build scripts, a compiler, and libraries, and
242 returns an installed package. As a pure function, its result depends
243 solely on its inputs---for instance, it cannot refer to software or
244 scripts that were not explicitly passed as inputs. A build function
245 always produces the same result when passed a given set of inputs. It
246 cannot alter the system's environment in
247 any way; for instance, it cannot create, modify, or delete files outside
248 of its build and installation directories. This is achieved by running
249 build processes in isolated environments (or @dfn{containers}), where only their
250 explicit inputs are visible.
253 The result of package build functions is @dfn{cached} in the file
254 system, in a special directory called @dfn{the store} (@pxref{The
255 Store}). Each package is installed in a directory of its own, in the
256 store---by default under @file{/gnu/store}. The directory name contains
257 a hash of all the inputs used to build that package; thus, changing an
258 input yields a different directory name.
260 This approach is the foundation of Guix's salient features: support for
261 transactional package upgrade and rollback, per-user installation, and
262 garbage collection of packages (@pxref{Features}).
264 Guix has a command-line interface, which allows users to build, install,
265 upgrade, and remove packages, as well as a Scheme programming interface.
267 @cindex Guix System Distribution
269 Last but not least, Guix is used to build a distribution of the GNU
270 system, with many GNU and non-GNU free software packages. The Guix
271 System Distribution, or GNU@tie{}GuixSD, takes advantage of the core
272 properties of Guix at the system level. With GuixSD, users
273 @emph{declare} all aspects of the operating system configuration, and
274 Guix takes care of instantiating that configuration in a reproducible,
275 stateless fashion. @xref{GNU Distribution}.
277 @c *********************************************************************
279 @chapter Installation
281 GNU Guix is available for download from its website at
282 @url{http://www.gnu.org/software/guix/}. This section describes the
283 software requirements of Guix, as well as how to install it and get
286 Note that this section is concerned with the installation of the package
287 manager, which can be done on top of a running GNU/Linux system. If,
288 instead, you want to install the complete GNU operating system,
289 @pxref{System Installation}.
292 * Binary Installation:: Getting Guix running in no time!
293 * Requirements:: Software needed to build and run Guix.
294 * Running the Test Suite:: Testing Guix.
295 * Setting Up the Daemon:: Preparing the build daemon's environment.
296 * Invoking guix-daemon:: Running the build daemon.
297 * Application Setup:: Application-specific setup.
300 @node Binary Installation
301 @section Binary Installation
303 This section describes how to install Guix on an arbitrary system from a
304 self-contained tarball providing binaries for Guix and for all its
305 dependencies. This is often quicker than installing from source, which
306 is described in the next sections. The only requirement is to have
309 Installing goes along these lines:
313 Download the binary tarball from
314 @indicateurl{ftp://alpha.gnu.org/gnu/guix/guix-binary-@value{VERSION}.@var{system}.tar.xz}@footnote{As
315 usual, make sure to download the associated @file{.sig} file and to
316 verify the authenticity of the tarball against it!}, where @var{system}
317 is @code{x86_64-linux} for an @code{x86_64} machine already running the
318 kernel Linux, and so on.
325 # tar --warning=no-timestamp -xf \
326 guix-binary-@value{VERSION}.@var{system}.tar.xz
327 # mv var/guix /var/ && mv gnu /
330 This creates @file{/gnu/store} (@pxref{The Store}) and @file{/var/guix}.
331 The latter contains a ready-to-use profile for @code{root} (see next
334 Do @emph{not} unpack the tarball on a working Guix system since that
335 would overwrite its own essential files.
337 The @code{--warning=no-timestamp} option makes sure GNU@tie{}tar does
338 not emit warnings about ``implausibly old time stamps'' (such
339 warnings were triggered by GNU@tie{}tar 1.26 and older; recent
341 They stem from the fact that all the
342 files in the archive have their modification time set to zero (which
343 means January 1st, 1970.) This is done on purpose to make sure the
344 archive content is independent of its creation time, thus making it
348 Make @code{root}'s profile available under @file{~/.guix-profile}:
351 # ln -sf /var/guix/profiles/per-user/root/guix-profile \
356 Create the group and user accounts for build users as explained below
357 (@pxref{Build Environment Setup}).
363 # ~root/.guix-profile/bin/guix-daemon --build-users-group=guixbuild
366 On hosts using the systemd init system, drop
367 @file{~root/.guix-profile/lib/systemd/system/guix-daemon.service} in
368 @file{/etc/systemd/system}.
370 Likewise, on hosts using the Upstart init system, drop
371 @file{~root/.guix-profile/lib/upstart/system/guix-daemon.conf} in
375 Make the @command{guix} command available to other users on the machine,
379 # mkdir -p /usr/local/bin
381 # ln -s /var/guix/profiles/per-user/root/guix-profile/bin/guix
385 To use substitutes from @code{hydra.gnu.org} (@pxref{Substitutes}),
389 # guix archive --authorize < ~root/.guix-profile/share/guix/hydra.gnu.org.pub
393 And that's it! For additional tips and tricks, @pxref{Application
396 The @code{guix} package must remain available in @code{root}'s
397 profile, or it would become subject to garbage collection---in which
398 case you would find yourself badly handicapped by the lack of the
399 @command{guix} command.
401 The tarball in question can be (re)produced and verified simply by
402 running the following command in the Guix source tree:
405 make guix-binary.@var{system}.tar.xz
410 @section Requirements
412 This section lists requirements when building Guix from source. The
413 build procedure for Guix is the same as for other GNU software, and is
414 not covered here. Please see the files @file{README} and @file{INSTALL}
415 in the Guix source tree for additional details.
417 GNU Guix depends on the following packages:
420 @item @url{http://gnu.org/software/guile/, GNU Guile}, version 2.0.7 or later;
421 @item @url{http://gnupg.org/, GNU libgcrypt};
422 @item @url{http://www.gnu.org/software/make/, GNU Make}.
425 The following dependencies are optional:
430 @url{http://savannah.nongnu.org/projects/guile-json/, Guile-JSON} will
431 allow you to use the @command{guix import pypi} command (@pxref{Invoking
432 guix import}). It is of
433 interest primarily for developers and not for casual users.
435 Installing @uref{http://gnutls.org/, GnuTLS-Guile} will
436 allow you to access @code{https} URLs with the @command{guix download}
437 command (@pxref{Invoking guix download}), the @command{guix import pypi}
438 command, and the @command{guix import cpan} command. This is primarily
439 of interest to developers. @xref{Guile Preparations, how to install the
440 GnuTLS bindings for Guile,, gnutls-guile, GnuTLS-Guile}.
443 Unless @code{--disable-daemon} was passed to @command{configure}, the
444 following packages are also needed:
447 @item @url{http://sqlite.org, SQLite 3};
448 @item @url{http://www.bzip.org, libbz2};
449 @item @url{http://gcc.gnu.org, GCC's g++}, with support for the
453 When a working installation of @url{http://nixos.org/nix/, the Nix package
454 manager} is available, you
455 can instead configure Guix with @code{--disable-daemon}. In that case,
456 Nix replaces the three dependencies above.
458 Guix is compatible with Nix, so it is possible to share the same store
459 between both. To do so, you must pass @command{configure} not only the
460 same @code{--with-store-dir} value, but also the same
461 @code{--localstatedir} value. The latter is essential because it
462 specifies where the database that stores metadata about the store is
463 located, among other things. The default values for Nix are
464 @code{--with-store-dir=/nix/store} and @code{--localstatedir=/nix/var}.
465 Note that @code{--disable-daemon} is not required if
466 your goal is to share the store with Nix.
468 @node Running the Test Suite
469 @section Running the Test Suite
471 After a successful @command{configure} and @code{make} run, it is a good
472 idea to run the test suite. It can help catch issues with the setup or
473 environment, or bugs in Guix itself---and really, reporting test
474 failures is a good way to help improve the software. To run the test
481 Test cases can run in parallel: you can use the @code{-j} option of
482 GNU@tie{}make to speed things up. The first run may take a few minutes
483 on a recent machine; subsequent runs will be faster because the store
484 that is created for test purposes will already have various things in
487 Upon failure, please email @email{bug-guix@@gnu.org} and attach the
488 @file{test-suite.log} file. When @file{tests/@var{something}.scm}
489 fails, please also attach the @file{@var{something}.log} file available
490 in the top-level build directory. Please specify the Guix version being
491 used as well as version numbers of the dependencies
492 (@pxref{Requirements}) in your message.
494 @node Setting Up the Daemon
495 @section Setting Up the Daemon
498 Operations such as building a package or running the garbage collector
499 are all performed by a specialized process, the @dfn{build daemon}, on
500 behalf of clients. Only the daemon may access the store and its
501 associated database. Thus, any operation that manipulates the store
502 goes through the daemon. For instance, command-line tools such as
503 @command{guix package} and @command{guix build} communicate with the
504 daemon (@i{via} remote procedure calls) to instruct it what to do.
506 The following sections explain how to prepare the build daemon's
507 environment. Also @ref{Substitutes}, for information on how to allow
508 the daemon to download pre-built binaries.
511 * Build Environment Setup:: Preparing the isolated build environment.
512 * Daemon Offload Setup:: Offloading builds to remote machines.
515 @node Build Environment Setup
516 @subsection Build Environment Setup
518 In a standard multi-user setup, Guix and its daemon---the
519 @command{guix-daemon} program---are installed by the system
520 administrator; @file{/gnu/store} is owned by @code{root} and
521 @command{guix-daemon} runs as @code{root}. Unprivileged users may use
522 Guix tools to build packages or otherwise access the store, and the
523 daemon will do it on their behalf, ensuring that the store is kept in a
524 consistent state, and allowing built packages to be shared among users.
527 When @command{guix-daemon} runs as @code{root}, you may not want package
528 build processes themselves to run as @code{root} too, for obvious
529 security reasons. To avoid that, a special pool of @dfn{build users}
530 should be created for use by build processes started by the daemon.
531 These build users need not have a shell and a home directory: they will
532 just be used when the daemon drops @code{root} privileges in build
533 processes. Having several such users allows the daemon to launch
534 distinct build processes under separate UIDs, which guarantees that they
535 do not interfere with each other---an essential feature since builds are
536 regarded as pure functions (@pxref{Introduction}).
538 On a GNU/Linux system, a build user pool may be created like this (using
539 Bash syntax and the @code{shadow} commands):
541 @c See http://lists.gnu.org/archive/html/bug-guix/2013-01/msg00239.html
542 @c for why `-G' is needed.
544 # groupadd --system guixbuild
545 # for i in `seq -w 1 10`;
547 useradd -g guixbuild -G guixbuild \
548 -d /var/empty -s `which nologin` \
549 -c "Guix build user $i" --system \
555 The number of build users determines how many build jobs may run in
556 parallel, as specified by the @option{--max-jobs} option
557 (@pxref{Invoking guix-daemon, @option{--max-jobs}}). The
558 @code{guix-daemon} program may then be run as @code{root} with the
559 following command@footnote{If your machine uses the systemd init system,
560 dropping the @file{@var{prefix}/lib/systemd/system/guix-daemon.service}
561 file in @file{/etc/systemd/system} will ensure that
562 @command{guix-daemon} is automatically started. Similarly, if your
563 machine uses the Upstart init system, drop the
564 @file{@var{prefix}/lib/upstart/system/guix-daemon.conf}
565 file in @file{/etc/init}.}:
568 # guix-daemon --build-users-group=guixbuild
573 This way, the daemon starts build processes in a chroot, under one of
574 the @code{guixbuilder} users. On GNU/Linux, by default, the chroot
575 environment contains nothing but:
577 @c Keep this list in sync with libstore/build.cc! -----------------------
580 a minimal @code{/dev} directory, created mostly independently from the
581 host @code{/dev}@footnote{``Mostly'', because while the set of files
582 that appear in the chroot's @code{/dev} is fixed, most of these files
583 can only be created if the host has them.};
586 the @code{/proc} directory; it only shows the container's processes
587 since a separate PID name space is used;
590 @file{/etc/passwd} with an entry for the current user and an entry for
594 @file{/etc/group} with an entry for the user's group;
597 @file{/etc/hosts} with an entry that maps @code{localhost} to
601 a writable @file{/tmp} directory.
604 You can influence the directory where the daemon stores build trees
605 @i{via} the @code{TMPDIR} environment variable. However, the build tree
606 within the chroot is always @file{/tmp/nix-build-@var{name}.drv-0},
607 where @var{name} is the derivation name---e.g., @code{coreutils-8.24}.
608 This way, the value of @code{TMPDIR} does not leak inside build
609 environments, which avoids discrepancies in cases where build processes
610 capture the name of their build tree.
612 If you are installing Guix as an unprivileged user, it is still possible
613 to run @command{guix-daemon} provided you pass @code{--disable-chroot}.
614 However, build processes will not be isolated from one another, and not
615 from the rest of the system. Thus, build processes may interfere with
616 each other, and may access programs, libraries, and other files
617 available on the system---making it much harder to view them as
618 @emph{pure} functions.
621 @node Daemon Offload Setup
622 @subsection Using the Offload Facility
626 When desired, the build daemon can @dfn{offload}
627 derivation builds to other machines
628 running Guix, using the @code{offload} @dfn{build hook}. When that
629 feature is enabled, a list of user-specified build machines is read from
630 @file{/etc/guix/machines.scm}; anytime a build is requested, for
631 instance via @code{guix build}, the daemon attempts to offload it to one
632 of the machines that satisfies the derivation's constraints, in
633 particular its system type---e.g., @file{x86_64-linux}. Missing
634 prerequisites for the build are copied over SSH to the target machine,
635 which then proceeds with the build; upon success the output(s) of the
636 build are copied back to the initial machine.
638 The @file{/etc/guix/machines.scm} file typically looks like this:
642 (name "eightysix.example.org")
643 (system "x86_64-linux")
645 (speed 2.)) ; incredibly fast!
648 (name "meeps.example.org")
649 (system "mips64el-linux")
652 (string-append (getenv "HOME")
653 "/.lsh/identity-for-guix"))))
657 In the example above we specify a list of two build machines, one for
658 the @code{x86_64} architecture and one for the @code{mips64el}
661 In fact, this file is---not surprisingly!---a Scheme file that is
662 evaluated when the @code{offload} hook is started. Its return value
663 must be a list of @code{build-machine} objects. While this example
664 shows a fixed list of build machines, one could imagine, say, using
665 DNS-SD to return a list of potential build machines discovered in the
666 local network (@pxref{Introduction, Guile-Avahi,, guile-avahi, Using
667 Avahi in Guile Scheme Programs}). The @code{build-machine} data type is
670 @deftp {Data Type} build-machine
671 This data type represents build machines the daemon may offload builds
672 to. The important fields are:
677 The remote machine's host name.
680 The remote machine's system type---e.g., @code{"x86_64-linux"}.
683 The user account to use when connecting to the remote machine over SSH.
684 Note that the SSH key pair must @emph{not} be passphrase-protected, to
685 allow non-interactive logins.
689 A number of optional fields may be specified:
694 Port number of the machine's SSH server (default: 22).
697 The SSH private key file to use when connecting to the machine.
699 Currently offloading uses GNU@tie{}lsh as its SSH client
700 (@pxref{Invoking lsh,,, GNU lsh Manual}). Thus, the key file here must
701 be an lsh key file. This may change in the future, though.
703 @item parallel-builds
704 The number of builds that may run in parallel on the machine (1 by
708 A ``relative speed factor''. The offload scheduler will tend to prefer
709 machines with a higher speed factor.
712 A list of strings denoting specific features supported by the machine.
713 An example is @code{"kvm"} for machines that have the KVM Linux modules
714 and corresponding hardware support. Derivations can request features by
715 name, and they will be scheduled on matching build machines.
720 The @code{guix} command must be in the search path on the build
721 machines, since offloading works by invoking the @code{guix archive} and
722 @code{guix build} commands. In addition, the Guix modules must be in
723 @code{$GUILE_LOAD_PATH} on the build machine---you can check whether
724 this is the case by running:
727 lsh build-machine guile -c '(use-modules (guix config))'
730 There's one last thing to do once @file{machines.scm} is in place. As
731 explained above, when offloading, files are transferred back and forth
732 between the machine stores. For this to work, you first need to
733 generate a key pair on each machine to allow the daemon to export signed
734 archives of files from the store (@pxref{Invoking guix archive}):
737 # guix archive --generate-key
741 Each build machine must authorize the key of the master machine so that
742 it accepts store items it receives from the master:
745 # guix archive --authorize < master-public-key.txt
749 Likewise, the master machine must authorize the key of each build machine.
751 All the fuss with keys is here to express pairwise mutual trust
752 relations between the master and the build machines. Concretely, when
753 the master receives files from a build machine (and @i{vice versa}), its
754 build daemon can make sure they are genuine, have not been tampered
755 with, and that they are signed by an authorized key.
758 @node Invoking guix-daemon
759 @section Invoking @command{guix-daemon}
761 The @command{guix-daemon} program implements all the functionality to
762 access the store. This includes launching build processes, running the
763 garbage collector, querying the availability of a build result, etc. It
764 is normally run as @code{root} like this:
767 # guix-daemon --build-users-group=guixbuild
771 For details on how to set it up, @pxref{Setting Up the Daemon}.
774 @cindex container, build environment
775 @cindex build environment
776 @cindex reproducible builds
777 By default, @command{guix-daemon} launches build processes under
778 different UIDs, taken from the build group specified with
779 @code{--build-users-group}. In addition, each build process is run in a
780 chroot environment that only contains the subset of the store that the
781 build process depends on, as specified by its derivation
782 (@pxref{Programming Interface, derivation}), plus a set of specific
783 system directories. By default, the latter contains @file{/dev} and
784 @file{/dev/pts}. Furthermore, on GNU/Linux, the build environment is a
785 @dfn{container}: in addition to having its own file system tree, it has
786 a separate mount name space, its own PID name space, network name space,
787 etc. This helps achieve reproducible builds (@pxref{Features}).
789 When the daemon performs a build on behalf of the user, it creates a
790 build directory under @file{/tmp} or under the directory specified by
791 its @code{TMPDIR} environment variable; this directory is shared with
792 the container for the duration of the build. Be aware that using a
793 directory other than @file{/tmp} can affect build results---for example,
794 with a longer directory name, a build process that uses Unix-domain
795 sockets might hit the name length limitation for @code{sun_path}, which
796 it would otherwise not hit.
798 The build directory is automatically deleted upon completion, unless the
799 build failed and the client specified @option{--keep-failed}
800 (@pxref{Invoking guix build, @option{--keep-failed}}).
802 The following command-line options are supported:
805 @item --build-users-group=@var{group}
806 Take users from @var{group} to run build processes (@pxref{Setting Up
807 the Daemon, build users}).
809 @item --no-substitutes
811 Do not use substitutes for build products. That is, always build things
812 locally instead of allowing downloads of pre-built binaries
813 (@pxref{Substitutes}).
815 By default substitutes are used, unless the client---such as the
816 @command{guix package} command---is explicitly invoked with
817 @code{--no-substitutes}.
819 When the daemon runs with @code{--no-substitutes}, clients can still
820 explicitly enable substitution @i{via} the @code{set-build-options}
821 remote procedure call (@pxref{The Store}).
823 @item --substitute-urls=@var{urls}
824 @anchor{daemon-substitute-urls}
825 Consider @var{urls} the default whitespace-separated list of substitute
826 source URLs. When this option is omitted, @indicateurl{http://hydra.gnu.org}
829 This means that substitutes may be downloaded from @var{urls}, as long
830 as they are signed by a trusted signature (@pxref{Substitutes}).
833 @item --no-build-hook
834 Do not use the @dfn{build hook}.
836 The build hook is a helper program that the daemon can start and to
837 which it submits build requests. This mechanism is used to offload
838 builds to other machines (@pxref{Daemon Offload Setup}).
840 @item --cache-failures
841 Cache build failures. By default, only successful builds are cached.
843 When this option is used, @command{guix gc --list-failures} can be used
844 to query the set of store items marked as failed; @command{guix gc
845 --clear-failures} removes store items from the set of cached failures.
846 @xref{Invoking guix gc}.
848 @item --cores=@var{n}
850 Use @var{n} CPU cores to build each derivation; @code{0} means as many
853 The default value is @code{0}, but it may be overridden by clients, such
854 as the @code{--cores} option of @command{guix build} (@pxref{Invoking
857 The effect is to define the @code{NIX_BUILD_CORES} environment variable
858 in the build process, which can then use it to exploit internal
859 parallelism---for instance, by running @code{make -j$NIX_BUILD_CORES}.
861 @item --max-jobs=@var{n}
863 Allow at most @var{n} build jobs in parallel. The default value is
864 @code{1}. Setting it to @code{0} means that no builds will be performed
865 locally; instead, the daemon will offload builds (@pxref{Daemon Offload
866 Setup}), or simply fail.
868 @item --rounds=@var{N}
869 Build each derivation @var{n} times in a row, and raise an error if
870 consecutive build results are not bit-for-bit identical. Note that this
871 setting can be overridden by clients such as @command{guix build}
872 (@pxref{Invoking guix build}).
875 Produce debugging output.
877 This is useful to debug daemon start-up issues, but then it may be
878 overridden by clients, for example the @code{--verbosity} option of
879 @command{guix build} (@pxref{Invoking guix build}).
881 @item --chroot-directory=@var{dir}
882 Add @var{dir} to the build chroot.
884 Doing this may change the result of build processes---for instance if
885 they use optional dependencies found in @var{dir} when it is available,
886 and not otherwise. For that reason, it is not recommended to do so.
887 Instead, make sure that each derivation declares all the inputs that it
890 @item --disable-chroot
891 Disable chroot builds.
893 Using this option is not recommended since, again, it would allow build
894 processes to gain access to undeclared dependencies. It is necessary,
895 though, when @command{guix-daemon} is running under an unprivileged user
898 @item --disable-log-compression
899 Disable compression of the build logs.
901 Unless @code{--lose-logs} is used, all the build logs are kept in the
902 @var{localstatedir}. To save space, the daemon automatically compresses
903 them with bzip2 by default. This option disables that.
905 @item --disable-deduplication
906 @cindex deduplication
907 Disable automatic file ``deduplication'' in the store.
909 By default, files added to the store are automatically ``deduplicated'':
910 if a newly added file is identical to another one found in the store,
911 the daemon makes the new file a hard link to the other file. This can
912 noticeably reduce disk usage, at the expense of slightly increased
913 input/output load at the end of a build process. This option disables
916 @item --gc-keep-outputs[=yes|no]
917 Tell whether the garbage collector (GC) must keep outputs of live
920 When set to ``yes'', the GC will keep the outputs of any live derivation
921 available in the store---the @code{.drv} files. The default is ``no'',
922 meaning that derivation outputs are kept only if they are GC roots.
924 @item --gc-keep-derivations[=yes|no]
925 Tell whether the garbage collector (GC) must keep derivations
926 corresponding to live outputs.
928 When set to ``yes'', as is the case by default, the GC keeps
929 derivations---i.e., @code{.drv} files---as long as at least one of their
930 outputs is live. This allows users to keep track of the origins of
931 items in their store. Setting it to ``no'' saves a bit of disk space.
933 Note that when both @code{--gc-keep-derivations} and
934 @code{--gc-keep-outputs} are used, the effect is to keep all the build
935 prerequisites (the sources, compiler, libraries, and other build-time
936 tools) of live objects in the store, regardless of whether these
937 prerequisites are live. This is convenient for developers since it
938 saves rebuilds or downloads.
940 @item --impersonate-linux-2.6
941 On Linux-based systems, impersonate Linux 2.6. This means that the
942 kernel's @code{uname} system call will report 2.6 as the release number.
944 This might be helpful to build programs that (usually wrongfully) depend
945 on the kernel version number.
948 Do not keep build logs. By default they are kept under
949 @code{@var{localstatedir}/guix/log}.
951 @item --system=@var{system}
952 Assume @var{system} as the current system type. By default it is the
953 architecture/kernel pair found at configure time, such as
956 @item --listen=@var{socket}
957 Listen for connections on @var{socket}, the file name of a Unix-domain
958 socket. The default socket is
959 @file{@var{localstatedir}/daemon-socket/socket}. This option is only
960 useful in exceptional circumstances, such as if you need to run several
961 daemons on the same machine.
965 @node Application Setup
966 @section Application Setup
968 When using Guix on top of GNU/Linux distribution other than GuixSD---a
969 so-called @dfn{foreign distro}---a few additional steps are needed to
970 get everything in place. Here are some of them.
974 @anchor{locales-and-locpath}
975 @cindex locales, when not on GuixSD
978 Packages installed @i{via} Guix will not use the host system's locale
979 data. Instead, you must first install one of the locale packages
980 available with Guix and then define the @code{GUIX_LOCPATH} environment
984 $ guix package -i glibc-locales
985 $ export GUIX_LOCPATH=$HOME/.guix-profile/lib/locale
988 Note that the @code{glibc-locales} package contains data for all the
989 locales supported by the GNU@tie{}libc and weighs in at around
990 110@tie{}MiB. Alternately, the @code{glibc-utf8-locales} is smaller but
991 limited to a few UTF-8 locales.
993 The @code{GUIX_LOCPATH} variable plays a role similar to @code{LOCPATH}
994 (@pxref{Locale Names, @code{LOCPATH},, libc, The GNU C Library Reference
995 Manual}). There are two important differences though:
999 @code{GUIX_LOCPATH} is honored only by Guix's libc, and not by the libc
1000 provided by foreign distros. Thus, using @code{GUIX_LOCPATH} allows you
1001 to make sure the the foreign distro's programs will not end up loading
1002 incompatible locale data.
1005 libc suffixes each entry of @code{GUIX_LOCPATH} with @code{/X.Y}, where
1006 @code{X.Y} is the libc version---e.g., @code{2.22}. This means that,
1007 should your Guix profile contain a mixture of programs linked against
1008 different libc version, each libc version will only try to load locale
1009 data in the right format.
1012 This is important because the locale data format used by different libc
1013 versions may be incompatible.
1015 @subsection X11 Fonts
1017 The majority of graphical applications use Fontconfig to locate and
1018 load fonts and perform X11-client-side rendering. Guix's
1019 @code{fontconfig} package looks for fonts in @file{$HOME/.guix-profile}
1020 by default. Thus, to allow graphical applications installed with Guix
1021 to display fonts, you will have to install fonts with Guix as well.
1022 Essential font packages include @code{gs-fonts}, @code{font-dejavu}, and
1023 @code{font-gnu-freefont-ttf}.
1025 To display text written in Chinese languages, Japanese, or Korean in
1026 graphical applications, consider installing
1027 @code{font-adobe-source-han-sans} or @code{font-wqy-zenhei}. The former
1028 has multiple outputs, one per language family (@pxref{Packages with
1029 Multiple Outputs}). For instance, the following command installs fonts
1030 for Chinese languages:
1033 guix package -i font-adobe-source-han-sans:cn
1038 @c *********************************************************************
1039 @node Package Management
1040 @chapter Package Management
1042 The purpose of GNU Guix is to allow users to easily install, upgrade, and
1043 remove software packages, without having to know about their build
1044 procedure or dependencies. Guix also goes beyond this obvious set of
1047 This chapter describes the main features of Guix, as well as the package
1048 management tools it provides. Two user interfaces are provided for
1049 routine package management tasks: A command-line interface described below
1050 (@pxref{Invoking guix package, @code{guix package}}), as well as a visual user
1051 interface in Emacs described in a subsequent chapter (@pxref{Emacs Interface}).
1054 * Features:: How Guix will make your life brighter.
1055 * Invoking guix package:: Package installation, removal, etc.
1056 * Substitutes:: Downloading pre-built binaries.
1057 * Packages with Multiple Outputs:: Single source package, multiple outputs.
1058 * Invoking guix gc:: Running the garbage collector.
1059 * Invoking guix pull:: Fetching the latest Guix and distribution.
1060 * Invoking guix archive:: Exporting and importing store files.
1066 When using Guix, each package ends up in the @dfn{package store}, in its
1067 own directory---something that resembles
1068 @file{/gnu/store/xxx-package-1.2}, where @code{xxx} is a base32 string
1069 (note that Guix comes with an Emacs extension to shorten those file
1070 names, @pxref{Emacs Prettify}.)
1072 Instead of referring to these directories, users have their own
1073 @dfn{profile}, which points to the packages that they actually want to
1074 use. These profiles are stored within each user's home directory, at
1075 @code{$HOME/.guix-profile}.
1077 For example, @code{alice} installs GCC 4.7.2. As a result,
1078 @file{/home/alice/.guix-profile/bin/gcc} points to
1079 @file{/gnu/store/@dots{}-gcc-4.7.2/bin/gcc}. Now, on the same machine,
1080 @code{bob} had already installed GCC 4.8.0. The profile of @code{bob}
1081 simply continues to point to
1082 @file{/gnu/store/@dots{}-gcc-4.8.0/bin/gcc}---i.e., both versions of GCC
1083 coexist on the same system without any interference.
1085 The @command{guix package} command is the central tool to manage
1086 packages (@pxref{Invoking guix package}). It operates on those per-user
1087 profiles, and can be used @emph{with normal user privileges}.
1089 The command provides the obvious install, remove, and upgrade
1090 operations. Each invocation is actually a @emph{transaction}: either
1091 the specified operation succeeds, or nothing happens. Thus, if the
1092 @command{guix package} process is terminated during the transaction,
1093 or if a power outage occurs during the transaction, then the user's
1094 profile remains in its previous state, and remains usable.
1096 In addition, any package transaction may be @emph{rolled back}. So, if,
1097 for example, an upgrade installs a new version of a package that turns
1098 out to have a serious bug, users may roll back to the previous instance
1099 of their profile, which was known to work well. Similarly, the global
1100 system configuration is subject to transactional upgrades and roll-back
1101 (@pxref{Using the Configuration System}).
1103 All those packages in the package store may be @emph{garbage-collected}.
1104 Guix can determine which packages are still referenced by the user
1105 profiles, and remove those that are provably no longer referenced
1106 (@pxref{Invoking guix gc}). Users may also explicitly remove old
1107 generations of their profile so that the packages they refer to can be
1110 @cindex reproducibility
1111 @cindex reproducible builds
1112 Finally, Guix takes a @dfn{purely functional} approach to package
1113 management, as described in the introduction (@pxref{Introduction}).
1114 Each @file{/gnu/store} package directory name contains a hash of all the
1115 inputs that were used to build that package---compiler, libraries, build
1116 scripts, etc. This direct correspondence allows users to make sure a
1117 given package installation matches the current state of their
1118 distribution. It also helps maximize @dfn{build reproducibility}:
1119 thanks to the isolated build environments that are used, a given build
1120 is likely to yield bit-identical files when performed on different
1121 machines (@pxref{Invoking guix-daemon, container}).
1124 This foundation allows Guix to support @dfn{transparent binary/source
1125 deployment}. When a pre-built binary for a @file{/gnu/store} item is
1126 available from an external source---a @dfn{substitute}, Guix just
1127 downloads it and unpacks it;
1128 otherwise, it builds the package from source, locally
1129 (@pxref{Substitutes}).
1131 Control over the build environment is a feature that is also useful for
1132 developers. The @command{guix environment} command allows developers of
1133 a package to quickly set up the right development environment for their
1134 package, without having to manually install the package's dependencies
1135 in their profile (@pxref{Invoking guix environment}).
1137 @node Invoking guix package
1138 @section Invoking @command{guix package}
1140 The @command{guix package} command is the tool that allows users to
1141 install, upgrade, and remove packages, as well as rolling back to
1142 previous configurations. It operates only on the user's own profile,
1143 and works with normal user privileges (@pxref{Features}). Its syntax
1147 guix package @var{options}
1150 Primarily, @var{options} specifies the operations to be performed during
1151 the transaction. Upon completion, a new profile is created, but
1152 previous @dfn{generations} of the profile remain available, should the user
1155 For example, to remove @code{lua} and install @code{guile} and
1156 @code{guile-cairo} in a single transaction:
1159 guix package -r lua -i guile guile-cairo
1162 @command{guix package} also supports a @dfn{declarative approach}
1163 whereby the user specifies the exact set of packages to be available and
1164 passes it @i{via} the @option{--manifest} option
1165 (@pxref{profile-manifest, @option{--manifest}}).
1167 For each user, a symlink to the user's default profile is automatically
1168 created in @file{$HOME/.guix-profile}. This symlink always points to the
1169 current generation of the user's default profile. Thus, users can add
1170 @file{$HOME/.guix-profile/bin} to their @code{PATH} environment
1171 variable, and so on.
1172 @cindex search paths
1173 If you are not using the Guix System Distribution, consider adding the
1174 following lines to your @file{~/.bash_profile} (@pxref{Bash Startup
1175 Files,,, bash, The GNU Bash Reference Manual}) so that newly-spawned
1176 shells get all the right environment variable definitions:
1179 GUIX_PROFILE="$HOME/.guix-profile" \
1180 source "$HOME/.guix-profile/etc/profile"
1183 In a multi-user setup, user profiles are stored in a place registered as
1184 a @dfn{garbage-collector root}, which @file{$HOME/.guix-profile} points
1185 to (@pxref{Invoking guix gc}). That directory is normally
1186 @code{@var{localstatedir}/profiles/per-user/@var{user}}, where
1187 @var{localstatedir} is the value passed to @code{configure} as
1188 @code{--localstatedir}, and @var{user} is the user name. The
1189 @file{per-user} directory is created when @command{guix-daemon} is
1190 started, and the @var{user} sub-directory is created by @command{guix
1193 The @var{options} can be among the following:
1197 @item --install=@var{package} @dots{}
1198 @itemx -i @var{package} @dots{}
1199 Install the specified @var{package}s.
1201 Each @var{package} may specify either a simple package name, such as
1202 @code{guile}, or a package name followed by a hyphen and version number,
1203 such as @code{guile-1.8.8} or simply @code{guile-1.8} (in the latter
1204 case, the newest version prefixed by @code{1.8} is selected.)
1206 If no version number is specified, the
1207 newest available version will be selected. In addition, @var{package}
1208 may contain a colon, followed by the name of one of the outputs of the
1209 package, as in @code{gcc:doc} or @code{binutils-2.22:lib}
1210 (@pxref{Packages with Multiple Outputs}). Packages with a corresponding
1211 name (and optionally version) are searched for among the GNU
1212 distribution modules (@pxref{Package Modules}).
1214 @cindex propagated inputs
1215 Sometimes packages have @dfn{propagated inputs}: these are dependencies
1216 that automatically get installed along with the required package
1217 (@pxref{package-propagated-inputs, @code{propagated-inputs} in
1218 @code{package} objects}, for information about propagated inputs in
1219 package definitions).
1221 @anchor{package-cmd-propagated-inputs}
1222 An example is the GNU MPC library: its C header files refer to those of
1223 the GNU MPFR library, which in turn refer to those of the GMP library.
1224 Thus, when installing MPC, the MPFR and GMP libraries also get installed
1225 in the profile; removing MPC also removes MPFR and GMP---unless they had
1226 also been explicitly installed independently.
1228 Besides, packages sometimes rely on the definition of environment
1229 variables for their search paths (see explanation of
1230 @code{--search-paths} below). Any missing or possibly incorrect
1231 environment variable definitions are reported here.
1233 @c XXX: keep me up-to-date
1234 Finally, when installing a GNU package, the tool reports the
1235 availability of a newer upstream version. In the future, it may provide
1236 the option of installing directly from the upstream version, even if
1237 that version is not yet in the distribution.
1239 @item --install-from-expression=@var{exp}
1241 Install the package @var{exp} evaluates to.
1243 @var{exp} must be a Scheme expression that evaluates to a
1244 @code{<package>} object. This option is notably useful to disambiguate
1245 between same-named variants of a package, with expressions such as
1246 @code{(@@ (gnu packages base) guile-final)}.
1248 Note that this option installs the first output of the specified
1249 package, which may be insufficient when needing a specific output of a
1250 multiple-output package.
1252 @item --install-from-file=@var{file}
1253 @itemx -f @var{file}
1254 Install the package that the code within @var{file} evaluates to.
1256 As an example, @var{file} might contain a definition like this
1257 (@pxref{Defining Packages}):
1260 @verbatiminclude package-hello.scm
1263 Developers may find it useful to include such a @file{package.scm} file
1264 in the root of their project's source tree that can be used to test
1265 development snapshots and create reproducible development environments
1266 (@pxref{Invoking guix environment}).
1268 @item --remove=@var{package} @dots{}
1269 @itemx -r @var{package} @dots{}
1270 Remove the specified @var{package}s.
1272 As for @code{--install}, each @var{package} may specify a version number
1273 and/or output name in addition to the package name. For instance,
1274 @code{-r glibc:debug} would remove the @code{debug} output of
1277 @item --upgrade[=@var{regexp} @dots{}]
1278 @itemx -u [@var{regexp} @dots{}]
1279 Upgrade all the installed packages. If one or more @var{regexp}s are
1280 specified, upgrade only installed packages whose name matches a
1281 @var{regexp}. Also see the @code{--do-not-upgrade} option below.
1283 Note that this upgrades package to the latest version of packages found
1284 in the distribution currently installed. To update your distribution,
1285 you should regularly run @command{guix pull} (@pxref{Invoking guix
1288 @item --do-not-upgrade[=@var{regexp} @dots{}]
1289 When used together with the @code{--upgrade} option, do @emph{not}
1290 upgrade any packages whose name matches a @var{regexp}. For example, to
1291 upgrade all packages in the current profile except those containing the
1292 substring ``emacs'':
1295 $ guix package --upgrade . --do-not-upgrade emacs
1298 @item @anchor{profile-manifest}--manifest=@var{file}
1299 @itemx -m @var{file}
1300 @cindex profile declaration
1301 @cindex profile manifest
1302 Create a new generation of the profile from the manifest object
1303 returned by the Scheme code in @var{file}.
1305 This allows you to @emph{declare} the profile's contents rather than
1306 constructing it through a sequence of @code{--install} and similar
1307 commands. The advantage is that @var{file} can be put under version
1308 control, copied to different machines to reproduce the same profile, and
1311 @c FIXME: Add reference to (guix profile) documentation when available.
1312 @var{file} must return a @dfn{manifest} object, which is roughly a list
1315 @findex packages->manifest
1317 (use-package-modules guile emacs)
1322 ;; Use a specific package output.
1323 (list guile-2.0 "debug")))
1327 Roll back to the previous @dfn{generation} of the profile---i.e., undo
1328 the last transaction.
1330 When combined with options such as @code{--install}, roll back occurs
1331 before any other actions.
1333 When rolling back from the first generation that actually contains
1334 installed packages, the profile is made to point to the @dfn{zeroth
1335 generation}, which contains no files apart from its own meta-data.
1337 Installing, removing, or upgrading packages from a generation that has
1338 been rolled back to overwrites previous future generations. Thus, the
1339 history of a profile's generations is always linear.
1341 @item --switch-generation=@var{pattern}
1342 @itemx -S @var{pattern}
1343 Switch to a particular generation defined by @var{pattern}.
1345 @var{pattern} may be either a generation number or a number prefixed
1346 with ``+'' or ``-''. The latter means: move forward/backward by a
1347 specified number of generations. For example, if you want to return to
1348 the latest generation after @code{--roll-back}, use
1349 @code{--switch-generation=+1}.
1351 The difference between @code{--roll-back} and
1352 @code{--switch-generation=-1} is that @code{--switch-generation} will
1353 not make a zeroth generation, so if a specified generation does not
1354 exist, the current generation will not be changed.
1356 @item --search-paths[=@var{kind}]
1357 @cindex search paths
1358 Report environment variable definitions, in Bash syntax, that may be
1359 needed in order to use the set of installed packages. These environment
1360 variables are used to specify @dfn{search paths} for files used by some
1361 of the installed packages.
1363 For example, GCC needs the @code{CPATH} and @code{LIBRARY_PATH}
1364 environment variables to be defined so it can look for headers and
1365 libraries in the user's profile (@pxref{Environment Variables,,, gcc,
1366 Using the GNU Compiler Collection (GCC)}). If GCC and, say, the C
1367 library are installed in the profile, then @code{--search-paths} will
1368 suggest setting these variables to @code{@var{profile}/include} and
1369 @code{@var{profile}/lib}, respectively.
1371 The typical use case is to define these environment variables in the
1375 $ eval `guix package --search-paths`
1378 @var{kind} may be one of @code{exact}, @code{prefix}, or @code{suffix},
1379 meaning that the returned environment variable definitions will either
1380 be exact settings, or prefixes or suffixes of the current value of these
1381 variables. When omitted, @var{kind} defaults to @code{exact}.
1383 This option can also be used to compute the @emph{combined} search paths
1384 of several profiles. Consider this example:
1387 $ guix package -p foo -i guile
1388 $ guix package -p bar -i guile-json
1389 $ guix package -p foo -p bar --search-paths
1392 The last command above reports about the @code{GUILE_LOAD_PATH}
1393 variable, even though, taken individually, neither @file{foo} nor
1394 @file{bar} would lead to that recommendation.
1397 @item --profile=@var{profile}
1398 @itemx -p @var{profile}
1399 Use @var{profile} instead of the user's default profile.
1402 Produce verbose output. In particular, emit the environment's build log
1403 on the standard error port.
1406 Use the bootstrap Guile to build the profile. This option is only
1407 useful to distribution developers.
1411 In addition to these actions @command{guix package} supports the
1412 following options to query the current state of a profile, or the
1413 availability of packages:
1417 @item --search=@var{regexp}
1418 @itemx -s @var{regexp}
1419 List the available packages whose name, synopsis, or description matches
1420 @var{regexp}. Print all the meta-data of matching packages in
1421 @code{recutils} format (@pxref{Top, GNU recutils databases,, recutils,
1422 GNU recutils manual}).
1424 This allows specific fields to be extracted using the @command{recsel}
1425 command, for instance:
1428 $ guix package -s malloc | recsel -p name,version
1436 Similarly, to show the name of all the packages available under the
1437 terms of the GNU@tie{}LGPL version 3:
1440 $ guix package -s "" | recsel -p name -e 'license ~ "LGPL 3"'
1447 @item --show=@var{package}
1448 Show details about @var{package}, taken from the list of available packages, in
1449 @code{recutils} format (@pxref{Top, GNU recutils databases,, recutils, GNU
1453 $ guix package --show=python | recsel -p name,version
1461 You may also specify the full name of a package to only get details about a
1462 specific version of it:
1464 $ guix package --show=python-3.3.5 | recsel -p name,version
1471 @item --list-installed[=@var{regexp}]
1472 @itemx -I [@var{regexp}]
1473 List the currently installed packages in the specified profile, with the
1474 most recently installed packages shown last. When @var{regexp} is
1475 specified, list only installed packages whose name matches @var{regexp}.
1477 For each installed package, print the following items, separated by
1478 tabs: the package name, its version string, the part of the package that
1479 is installed (for instance, @code{out} for the default output,
1480 @code{include} for its headers, etc.), and the path of this package in
1483 @item --list-available[=@var{regexp}]
1484 @itemx -A [@var{regexp}]
1485 List packages currently available in the distribution for this system
1486 (@pxref{GNU Distribution}). When @var{regexp} is specified, list only
1487 installed packages whose name matches @var{regexp}.
1489 For each package, print the following items separated by tabs: its name,
1490 its version string, the parts of the package (@pxref{Packages with
1491 Multiple Outputs}), and the source location of its definition.
1493 @item --list-generations[=@var{pattern}]
1494 @itemx -l [@var{pattern}]
1495 Return a list of generations along with their creation dates; for each
1496 generation, show the installed packages, with the most recently
1497 installed packages shown last. Note that the zeroth generation is never
1500 For each installed package, print the following items, separated by
1501 tabs: the name of a package, its version string, the part of the package
1502 that is installed (@pxref{Packages with Multiple Outputs}), and the
1503 location of this package in the store.
1505 When @var{pattern} is used, the command returns only matching
1506 generations. Valid patterns include:
1509 @item @emph{Integers and comma-separated integers}. Both patterns denote
1510 generation numbers. For instance, @code{--list-generations=1} returns
1513 And @code{--list-generations=1,8,2} outputs three generations in the
1514 specified order. Neither spaces nor trailing commas are allowed.
1516 @item @emph{Ranges}. @code{--list-generations=2..9} prints the
1517 specified generations and everything in between. Note that the start of
1518 a range must be lesser than its end.
1520 It is also possible to omit the endpoint. For example,
1521 @code{--list-generations=2..}, returns all generations starting from the
1524 @item @emph{Durations}. You can also get the last @emph{N}@tie{}days, weeks,
1525 or months by passing an integer along with the first letter of the
1526 duration. For example, @code{--list-generations=20d} lists generations
1527 that are up to 20 days old.
1530 @item --delete-generations[=@var{pattern}]
1531 @itemx -d [@var{pattern}]
1532 When @var{pattern} is omitted, delete all generations except the current
1535 This command accepts the same patterns as @option{--list-generations}.
1536 When @var{pattern} is specified, delete the matching generations. When
1537 @var{pattern} specifies a duration, generations @emph{older} than the
1538 specified duration match. For instance, @code{--delete-generations=1m}
1539 deletes generations that are more than one month old.
1541 If the current generation matches, it is @emph{not} deleted. Also, the
1542 zeroth generation is never deleted.
1544 Note that deleting generations prevents roll-back to them.
1545 Consequently, this command must be used with care.
1549 Finally, since @command{guix package} may actually start build
1550 processes, it supports all the common build options that @command{guix
1551 build} supports (@pxref{Invoking guix build, common build options}).
1554 @section Substitutes
1557 @cindex pre-built binaries
1558 Guix supports transparent source/binary deployment, which means that it
1559 can either build things locally, or download pre-built items from a
1560 server. We call these pre-built items @dfn{substitutes}---they are
1561 substitutes for local build results. In many cases, downloading a
1562 substitute is much faster than building things locally.
1564 Substitutes can be anything resulting from a derivation build
1565 (@pxref{Derivations}). Of course, in the common case, they are
1566 pre-built package binaries, but source tarballs, for instance, which
1567 also result from derivation builds, can be available as substitutes.
1569 The @code{hydra.gnu.org} server is a front-end to a build farm that
1570 builds packages from the GNU distribution continuously for some
1571 architectures, and makes them available as substitutes. This is the
1572 default source of substitutes; it can be overridden by passing the
1573 @option{--substitute-urls} option either to @command{guix-daemon}
1574 (@pxref{daemon-substitute-urls,, @code{guix-daemon --substitute-urls}})
1575 or to client tools such as @command{guix package}
1576 (@pxref{client-substitute-urls,, client @option{--substitute-urls}
1580 @cindex digital signatures
1581 To allow Guix to download substitutes from @code{hydra.gnu.org}, you
1582 must add its public key to the access control list (ACL) of archive
1583 imports, using the @command{guix archive} command (@pxref{Invoking guix
1584 archive}). Doing so implies that you trust @code{hydra.gnu.org} to not
1585 be compromised and to serve genuine substitutes.
1587 This public key is installed along with Guix, in
1588 @code{@var{prefix}/share/guix/hydra.gnu.org.pub}, where @var{prefix} is
1589 the installation prefix of Guix. If you installed Guix from source,
1590 make sure you checked the GPG signature of
1591 @file{guix-@value{VERSION}.tar.gz}, which contains this public key file.
1592 Then, you can run something like this:
1595 # guix archive --authorize < hydra.gnu.org.pub
1598 Once this is in place, the output of a command like @code{guix build}
1599 should change from something like:
1602 $ guix build emacs --dry-run
1603 The following derivations would be built:
1604 /gnu/store/yr7bnx8xwcayd6j95r2clmkdl1qh688w-emacs-24.3.drv
1605 /gnu/store/x8qsh1hlhgjx6cwsjyvybnfv2i37z23w-dbus-1.6.4.tar.gz.drv
1606 /gnu/store/1ixwp12fl950d15h2cj11c73733jay0z-alsa-lib-1.0.27.1.tar.bz2.drv
1607 /gnu/store/nlma1pw0p603fpfiqy7kn4zm105r5dmw-util-linux-2.21.drv
1615 $ guix build emacs --dry-run
1616 The following files would be downloaded:
1617 /gnu/store/pk3n22lbq6ydamyymqkkz7i69wiwjiwi-emacs-24.3
1618 /gnu/store/2ygn4ncnhrpr61rssa6z0d9x22si0va3-libjpeg-8d
1619 /gnu/store/71yz6lgx4dazma9dwn2mcjxaah9w77jq-cairo-1.12.16
1620 /gnu/store/7zdhgp0n1518lvfn8mb96sxqfmvqrl7v-libxrender-0.9.7
1625 This indicates that substitutes from @code{hydra.gnu.org} are usable and
1626 will be downloaded, when possible, for future builds.
1628 Guix ignores substitutes that are not signed, or that are not signed by
1629 one of the keys listed in the ACL. It also detects and raises an error
1630 when attempting to use a substitute that has been tampered with.
1632 The substitute mechanism can be disabled globally by running
1633 @code{guix-daemon} with @code{--no-substitutes} (@pxref{Invoking
1634 guix-daemon}). It can also be disabled temporarily by passing the
1635 @code{--no-substitutes} option to @command{guix package}, @command{guix
1636 build}, and other command-line tools.
1639 Today, each individual's control over their own computing is at the
1640 mercy of institutions, corporations, and groups with enough power and
1641 determination to subvert the computing infrastructure and exploit its
1642 weaknesses. While using @code{hydra.gnu.org} substitutes can be
1643 convenient, we encourage users to also build on their own, or even run
1644 their own build farm, such that @code{hydra.gnu.org} is less of an
1645 interesting target. One way to help is by publishing the software you
1646 build using @command{guix publish} so that others have one more choice
1647 of server to download substitutes from (@pxref{Invoking guix publish}).
1649 Guix has the foundations to maximize build reproducibility
1650 (@pxref{Features}). In most cases, independent builds of a given
1651 package or derivation should yield bit-identical results. Thus, through
1652 a diverse set of independent package builds, we can strengthen the
1653 integrity of our systems. The @command{guix challenge} command aims to
1654 help users assess substitute servers, and to assist developers in
1655 finding out about non-deterministic package builds (@pxref{Invoking guix
1656 challenge}). Similarly, the @option{--check} option of @command{guix
1657 build} allows users to check whether previously-installed substitutes
1658 are genuine by rebuilding them locally (@pxref{build-check,
1659 @command{guix build --check}}).
1661 In the future, we want Guix to have support to publish and retrieve
1662 binaries to/from other users, in a peer-to-peer fashion. If you would
1663 like to discuss this project, join us on @email{guix-devel@@gnu.org}.
1666 @node Packages with Multiple Outputs
1667 @section Packages with Multiple Outputs
1669 @cindex multiple-output packages
1670 @cindex package outputs
1672 Often, packages defined in Guix have a single @dfn{output}---i.e., the
1673 source package leads exactly one directory in the store. When running
1674 @command{guix package -i glibc}, one installs the default output of the
1675 GNU libc package; the default output is called @code{out}, but its name
1676 can be omitted as shown in this command. In this particular case, the
1677 default output of @code{glibc} contains all the C header files, shared
1678 libraries, static libraries, Info documentation, and other supporting
1681 Sometimes it is more appropriate to separate the various types of files
1682 produced from a single source package into separate outputs. For
1683 instance, the GLib C library (used by GTK+ and related packages)
1684 installs more than 20 MiB of reference documentation as HTML pages.
1685 To save space for users who do not need it, the documentation goes to a
1686 separate output, called @code{doc}. To install the main GLib output,
1687 which contains everything but the documentation, one would run:
1690 guix package -i glib
1693 The command to install its documentation is:
1696 guix package -i glib:doc
1699 Some packages install programs with different ``dependency footprints''.
1700 For instance, the WordNet package install both command-line tools and
1701 graphical user interfaces (GUIs). The former depend solely on the C
1702 library, whereas the latter depend on Tcl/Tk and the underlying X
1703 libraries. In this case, we leave the command-line tools in the default
1704 output, whereas the GUIs are in a separate output. This allows users
1705 who do not need the GUIs to save space. The @command{guix size} command
1706 can help find out about such situations (@pxref{Invoking guix size}).
1707 @command{guix graph} can also be helpful (@pxref{Invoking guix graph}).
1709 There are several such multiple-output packages in the GNU distribution.
1710 Other conventional output names include @code{lib} for libraries and
1711 possibly header files, @code{bin} for stand-alone programs, and
1712 @code{debug} for debugging information (@pxref{Installing Debugging
1713 Files}). The outputs of a packages are listed in the third column of
1714 the output of @command{guix package --list-available} (@pxref{Invoking
1718 @node Invoking guix gc
1719 @section Invoking @command{guix gc}
1721 @cindex garbage collector
1722 Packages that are installed but not used may be @dfn{garbage-collected}.
1723 The @command{guix gc} command allows users to explicitly run the garbage
1724 collector to reclaim space from the @file{/gnu/store} directory. It is
1725 the @emph{only} way to remove files from @file{/gnu/store}---removing
1726 files or directories manually may break it beyond repair!
1728 The garbage collector has a set of known @dfn{roots}: any file under
1729 @file{/gnu/store} reachable from a root is considered @dfn{live} and
1730 cannot be deleted; any other file is considered @dfn{dead} and may be
1731 deleted. The set of garbage collector roots includes default user
1732 profiles, and may be augmented with @command{guix build --root}, for
1733 example (@pxref{Invoking guix build}).
1735 Prior to running @code{guix gc --collect-garbage} to make space, it is
1736 often useful to remove old generations from user profiles; that way, old
1737 package builds referenced by those generations can be reclaimed. This
1738 is achieved by running @code{guix package --delete-generations}
1739 (@pxref{Invoking guix package}).
1741 The @command{guix gc} command has three modes of operation: it can be
1742 used to garbage-collect any dead files (the default), to delete specific
1743 files (the @code{--delete} option), to print garbage-collector
1744 information, or for more advanced queries. The garbage collection
1745 options are as follows:
1748 @item --collect-garbage[=@var{min}]
1749 @itemx -C [@var{min}]
1750 Collect garbage---i.e., unreachable @file{/gnu/store} files and
1751 sub-directories. This is the default operation when no option is
1754 When @var{min} is given, stop once @var{min} bytes have been collected.
1755 @var{min} may be a number of bytes, or it may include a unit as a
1756 suffix, such as @code{MiB} for mebibytes and @code{GB} for gigabytes
1757 (@pxref{Block size, size specifications,, coreutils, GNU Coreutils}).
1759 When @var{min} is omitted, collect all the garbage.
1763 Attempt to delete all the store files and directories specified as
1764 arguments. This fails if some of the files are not in the store, or if
1765 they are still live.
1767 @item --list-failures
1768 List store items corresponding to cached build failures.
1770 This prints nothing unless the daemon was started with
1771 @option{--cache-failures} (@pxref{Invoking guix-daemon,
1772 @option{--cache-failures}}).
1774 @item --clear-failures
1775 Remove the specified store items from the failed-build cache.
1777 Again, this option only makes sense when the daemon is started with
1778 @option{--cache-failures}. Otherwise, it does nothing.
1781 Show the list of dead files and directories still present in the
1782 store---i.e., files and directories no longer reachable from any root.
1785 Show the list of live store files and directories.
1789 In addition, the references among existing store files can be queried:
1795 List the references (respectively, the referrers) of store files given
1801 List the requisites of the store files passed as arguments. Requisites
1802 include the store files themselves, their references, and the references
1803 of these, recursively. In other words, the returned list is the
1804 @dfn{transitive closure} of the store files.
1806 @xref{Invoking guix size}, for a tool to profile the size of an
1807 element's closure. @xref{Invoking guix graph}, for a tool to visualize
1808 the graph of references.
1812 Lastly, the following options allow you to check the integrity of the
1813 store and to control disk usage.
1817 @item --verify[=@var{options}]
1818 @cindex integrity, of the store
1819 @cindex integrity checking
1820 Verify the integrity of the store.
1822 By default, make sure that all the store items marked as valid in the
1823 daemon's database actually exist in @file{/gnu/store}.
1825 When provided, @var{options} must a comma-separated list containing one
1826 or more of @code{contents} and @code{repair}.
1828 When passing @option{--verify=contents}, the daemon will compute the
1829 content hash of each store item and compare it against its hash in the
1830 database. Hash mismatches are reported as data corruptions. Because it
1831 traverses @emph{all the files in the store}, this command can take a
1832 long time, especially on systems with a slow disk drive.
1834 @cindex repairing the store
1835 Using @option{--verify=repair} or @option{--verify=contents,repair}
1836 causes the daemon to try to repair corrupt store items by fetching
1837 substitutes for them (@pxref{Substitutes}). Because repairing is not
1838 atomic, and thus potentially dangerous, it is available only to the
1839 system administrator.
1842 @cindex deduplication
1843 Optimize the store by hard-linking identical files---this is
1844 @dfn{deduplication}.
1846 The daemon performs deduplication after each successful build or archive
1847 import, unless it was started with @code{--disable-deduplication}
1848 (@pxref{Invoking guix-daemon, @code{--disable-deduplication}}). Thus,
1849 this option is primarily useful when the daemon was running with
1850 @code{--disable-deduplication}.
1854 @node Invoking guix pull
1855 @section Invoking @command{guix pull}
1857 Packages are installed or upgraded to the latest version available in
1858 the distribution currently available on your local machine. To update
1859 that distribution, along with the Guix tools, you must run @command{guix
1860 pull}: the command downloads the latest Guix source code and package
1861 descriptions, and deploys it.
1863 On completion, @command{guix package} will use packages and package
1864 versions from this just-retrieved copy of Guix. Not only that, but all
1865 the Guix commands and Scheme modules will also be taken from that latest
1866 version. New @command{guix} sub-commands added by the update also
1867 become available@footnote{Under the hood, @command{guix pull} updates
1868 the @file{~/.config/guix/latest} symbolic link to point to the latest
1869 Guix, and the @command{guix} command loads code from there.}.
1871 The @command{guix pull} command is usually invoked with no arguments,
1872 but it supports the following options:
1876 Produce verbose output, writing build logs to the standard error output.
1878 @item --url=@var{url}
1879 Download the source tarball of Guix from @var{url}.
1881 By default, the tarball is taken from its canonical address at
1882 @code{gnu.org}, for the stable branch of Guix.
1885 Use the bootstrap Guile to build the latest Guix. This option is only
1886 useful to Guix developers.
1890 @node Invoking guix archive
1891 @section Invoking @command{guix archive}
1893 The @command{guix archive} command allows users to @dfn{export} files
1894 from the store into a single archive, and to later @dfn{import} them.
1895 In particular, it allows store files to be transferred from one machine
1896 to another machine's store. For example, to transfer the @code{emacs}
1897 package to a machine connected over SSH, one would run:
1900 guix archive --export -r emacs | ssh the-machine guix archive --import
1904 Similarly, a complete user profile may be transferred from one machine
1905 to another like this:
1908 guix archive --export -r $(readlink -f ~/.guix-profile) | \
1909 ssh the-machine guix-archive --import
1913 However, note that, in both examples, all of @code{emacs} and the
1914 profile as well as all of their dependencies are transferred (due to
1915 @code{-r}), regardless of what is already available in the target
1916 machine's store. The @code{--missing} option can help figure out which
1917 items are missing from the target's store.
1919 Archives are stored in the ``Nix archive'' or ``Nar'' format, which is
1920 comparable in spirit to `tar', but with a few noteworthy differences
1921 that make it more appropriate for our purposes. First, rather than
1922 recording all Unix meta-data for each file, the Nar format only mentions
1923 the file type (regular, directory, or symbolic link); Unix permissions
1924 and owner/group are dismissed. Second, the order in which directory
1925 entries are stored always follows the order of file names according to
1926 the C locale collation order. This makes archive production fully
1929 When exporting, the daemon digitally signs the contents of the archive,
1930 and that digital signature is appended. When importing, the daemon
1931 verifies the signature and rejects the import in case of an invalid
1932 signature or if the signing key is not authorized.
1933 @c FIXME: Add xref to daemon doc about signatures.
1935 The main options are:
1939 Export the specified store files or packages (see below.) Write the
1940 resulting archive to the standard output.
1942 Dependencies are @emph{not} included in the output, unless
1943 @code{--recursive} is passed.
1947 When combined with @code{--export}, this instructs @command{guix
1948 archive} to include dependencies of the given items in the archive.
1949 Thus, the resulting archive is self-contained: it contains the closure
1950 of the exported store items.
1953 Read an archive from the standard input, and import the files listed
1954 therein into the store. Abort if the archive has an invalid digital
1955 signature, or if it is signed by a public key not among the authorized
1956 keys (see @code{--authorize} below.)
1959 Read a list of store file names from the standard input, one per line,
1960 and write on the standard output the subset of these files missing from
1963 @item --generate-key[=@var{parameters}]
1964 @cindex signing, archives
1965 Generate a new key pair for the daemons. This is a prerequisite before
1966 archives can be exported with @code{--export}. Note that this operation
1967 usually takes time, because it needs to gather enough entropy to
1968 generate the key pair.
1970 The generated key pair is typically stored under @file{/etc/guix}, in
1971 @file{signing-key.pub} (public key) and @file{signing-key.sec} (private
1972 key, which must be kept secret.) When @var{parameters} is omitted,
1973 an ECDSA key using the Ed25519 curve is generated, or, for Libgcrypt
1974 versions before 1.6.0, it is a 4096-bit RSA key.
1975 Alternately, @var{parameters} can specify
1976 @code{genkey} parameters suitable for Libgcrypt (@pxref{General
1977 public-key related Functions, @code{gcry_pk_genkey},, gcrypt, The
1978 Libgcrypt Reference Manual}).
1981 @cindex authorizing, archives
1982 Authorize imports signed by the public key passed on standard input.
1983 The public key must be in ``s-expression advanced format''---i.e., the
1984 same format as the @file{signing-key.pub} file.
1986 The list of authorized keys is kept in the human-editable file
1987 @file{/etc/guix/acl}. The file contains
1988 @url{http://people.csail.mit.edu/rivest/Sexp.txt, ``advanced-format
1989 s-expressions''} and is structured as an access-control list in the
1990 @url{http://theworld.com/~cme/spki.txt, Simple Public-Key Infrastructure
1993 @item --extract=@var{directory}
1994 @itemx -x @var{directory}
1995 Read a single-item archive as served by substitute servers
1996 (@pxref{Substitutes}) and extract it to @var{directory}. This is a
1997 low-level operation needed in only very narrow use cases; see below.
1999 For example, the following command extracts the substitute for Emacs
2000 served by @code{hydra.gnu.org} to @file{/tmp/emacs}:
2004 http://hydra.gnu.org/nar/@dots{}-emacs-24.5 \
2005 | bunzip2 | guix archive -x /tmp/emacs
2008 Single-item archives are different from multiple-item archives produced
2009 by @command{guix archive --export}; they contain a single store item,
2010 and they do @emph{not} embed a signature. Thus this operation does
2011 @emph{no} signature verification and its output should be considered
2014 The primary purpose of this operation is to facilitate inspection of
2015 archive contents coming from possibly untrusted substitute servers.
2019 To export store files as an archive to the standard output, run:
2022 guix archive --export @var{options} @var{specifications}...
2025 @var{specifications} may be either store file names or package
2026 specifications, as for @command{guix package} (@pxref{Invoking guix
2027 package}). For instance, the following command creates an archive
2028 containing the @code{gui} output of the @code{git} package and the main
2029 output of @code{emacs}:
2032 guix archive --export git:gui /gnu/store/...-emacs-24.3 > great.nar
2035 If the specified packages are not built yet, @command{guix archive}
2036 automatically builds them. The build process may be controlled with the
2037 same options that can be passed to the @command{guix build} command
2038 (@pxref{Invoking guix build, common build options}).
2040 @c *********************************************************************
2043 @c *********************************************************************
2044 @node Programming Interface
2045 @chapter Programming Interface
2047 GNU Guix provides several Scheme programming interfaces (APIs) to
2048 define, build, and query packages. The first interface allows users to
2049 write high-level package definitions. These definitions refer to
2050 familiar packaging concepts, such as the name and version of a package,
2051 its build system, and its dependencies. These definitions can then be
2052 turned into concrete build actions.
2054 Build actions are performed by the Guix daemon, on behalf of users. In a
2055 standard setup, the daemon has write access to the store---the
2056 @file{/gnu/store} directory---whereas users do not. The recommended
2057 setup also has the daemon perform builds in chroots, under a specific
2058 build users, to minimize interference with the rest of the system.
2061 Lower-level APIs are available to interact with the daemon and the
2062 store. To instruct the daemon to perform a build action, users actually
2063 provide it with a @dfn{derivation}. A derivation is a low-level
2064 representation of the build actions to be taken, and the environment in
2065 which they should occur---derivations are to package definitions what
2066 assembly is to C programs. The term ``derivation'' comes from the fact
2067 that build results @emph{derive} from them.
2069 This chapter describes all these APIs in turn, starting from high-level
2070 package definitions.
2073 * Defining Packages:: Defining new packages.
2074 * Build Systems:: Specifying how packages are built.
2075 * The Store:: Manipulating the package store.
2076 * Derivations:: Low-level interface to package derivations.
2077 * The Store Monad:: Purely functional interface to the store.
2078 * G-Expressions:: Manipulating build expressions.
2081 @node Defining Packages
2082 @section Defining Packages
2084 The high-level interface to package definitions is implemented in the
2085 @code{(guix packages)} and @code{(guix build-system)} modules. As an
2086 example, the package definition, or @dfn{recipe}, for the GNU Hello
2087 package looks like this:
2090 (define-module (gnu packages hello)
2091 #:use-module (guix packages)
2092 #:use-module (guix download)
2093 #:use-module (guix build-system gnu)
2094 #:use-module (guix licenses)
2095 #:use-module (gnu packages gawk))
2097 (define-public hello
2103 (uri (string-append "mirror://gnu/hello/hello-" version
2107 "0ssi1wpaf7plaswqqjwigppsg5fyh99vdlb9kzl7c9lng89ndq1i"))))
2108 (build-system gnu-build-system)
2109 (arguments `(#:configure-flags '("--enable-silent-rules")))
2110 (inputs `(("gawk" ,gawk)))
2111 (synopsis "Hello, GNU world: An example GNU package")
2112 (description "Guess what GNU Hello prints!")
2113 (home-page "http://www.gnu.org/software/hello/")
2118 Without being a Scheme expert, the reader may have guessed the meaning
2119 of the various fields here. This expression binds variable @code{hello}
2120 to a @code{<package>} object, which is essentially a record
2121 (@pxref{SRFI-9, Scheme records,, guile, GNU Guile Reference Manual}).
2122 This package object can be inspected using procedures found in the
2123 @code{(guix packages)} module; for instance, @code{(package-name hello)}
2124 returns---surprise!---@code{"hello"}.
2126 With luck, you may be able to import part or all of the definition of
2127 the package you are interested in from another repository, using the
2128 @code{guix import} command (@pxref{Invoking guix import}).
2130 In the example above, @var{hello} is defined into a module of its own,
2131 @code{(gnu packages hello)}. Technically, this is not strictly
2132 necessary, but it is convenient to do so: all the packages defined in
2133 modules under @code{(gnu packages @dots{})} are automatically known to
2134 the command-line tools (@pxref{Package Modules}).
2136 There are a few points worth noting in the above package definition:
2140 The @code{source} field of the package is an @code{<origin>} object
2141 (@pxref{origin Reference}, for the complete reference).
2142 Here, the @code{url-fetch} method from @code{(guix download)} is used,
2143 meaning that the source is a file to be downloaded over FTP or HTTP.
2145 The @code{mirror://gnu} prefix instructs @code{url-fetch} to use one of
2146 the GNU mirrors defined in @code{(guix download)}.
2148 The @code{sha256} field specifies the expected SHA256 hash of the file
2149 being downloaded. It is mandatory, and allows Guix to check the
2150 integrity of the file. The @code{(base32 @dots{})} form introduces the
2151 base32 representation of the hash. You can obtain this information with
2152 @code{guix download} (@pxref{Invoking guix download}) and @code{guix
2153 hash} (@pxref{Invoking guix hash}).
2156 When needed, the @code{origin} form can also have a @code{patches} field
2157 listing patches to be applied, and a @code{snippet} field giving a
2158 Scheme expression to modify the source code.
2161 @cindex GNU Build System
2162 The @code{build-system} field specifies the procedure to build the
2163 package (@pxref{Build Systems}). Here, @var{gnu-build-system}
2164 represents the familiar GNU Build System, where packages may be
2165 configured, built, and installed with the usual @code{./configure &&
2166 make && make check && make install} command sequence.
2169 The @code{arguments} field specifies options for the build system
2170 (@pxref{Build Systems}). Here it is interpreted by
2171 @var{gnu-build-system} as a request run @file{configure} with the
2172 @code{--enable-silent-rules} flag.
2175 The @code{inputs} field specifies inputs to the build process---i.e.,
2176 build-time or run-time dependencies of the package. Here, we define an
2177 input called @code{"gawk"} whose value is that of the @var{gawk}
2178 variable; @var{gawk} is itself bound to a @code{<package>} object.
2180 Note that GCC, Coreutils, Bash, and other essential tools do not need to
2181 be specified as inputs here. Instead, @var{gnu-build-system} takes care
2182 of ensuring that they are present (@pxref{Build Systems}).
2184 However, any other dependencies need to be specified in the
2185 @code{inputs} field. Any dependency not specified here will simply be
2186 unavailable to the build process, possibly leading to a build failure.
2189 @xref{package Reference}, for a full description of possible fields.
2191 Once a package definition is in place, the
2192 package may actually be built using the @code{guix build} command-line
2193 tool (@pxref{Invoking guix build}). You can easily jump back to the
2194 package definition using the @command{guix edit} command
2195 (@pxref{Invoking guix edit}).
2196 @xref{Packaging Guidelines}, for
2197 more information on how to test package definitions, and
2198 @ref{Invoking guix lint}, for information on how to check a definition
2199 for style conformance.
2201 Eventually, updating the package definition to a new upstream version
2202 can be partly automated by the @command{guix refresh} command
2203 (@pxref{Invoking guix refresh}).
2205 Behind the scenes, a derivation corresponding to the @code{<package>}
2206 object is first computed by the @code{package-derivation} procedure.
2207 That derivation is stored in a @code{.drv} file under @file{/gnu/store}.
2208 The build actions it prescribes may then be realized by using the
2209 @code{build-derivations} procedure (@pxref{The Store}).
2211 @deffn {Scheme Procedure} package-derivation @var{store} @var{package} [@var{system}]
2212 Return the @code{<derivation>} object of @var{package} for @var{system}
2213 (@pxref{Derivations}).
2215 @var{package} must be a valid @code{<package>} object, and @var{system}
2216 must be a string denoting the target system type---e.g.,
2217 @code{"x86_64-linux"} for an x86_64 Linux-based GNU system. @var{store}
2218 must be a connection to the daemon, which operates on the store
2219 (@pxref{The Store}).
2223 @cindex cross-compilation
2224 Similarly, it is possible to compute a derivation that cross-builds a
2225 package for some other system:
2227 @deffn {Scheme Procedure} package-cross-derivation @var{store} @
2228 @var{package} @var{target} [@var{system}]
2229 Return the @code{<derivation>} object of @var{package} cross-built from
2230 @var{system} to @var{target}.
2232 @var{target} must be a valid GNU triplet denoting the target hardware
2233 and operating system, such as @code{"mips64el-linux-gnu"}
2234 (@pxref{Configuration Names, GNU configuration triplets,, configure, GNU
2235 Configure and Build System}).
2239 * package Reference :: The package data type.
2240 * origin Reference:: The origin data type.
2244 @node package Reference
2245 @subsection @code{package} Reference
2247 This section summarizes all the options available in @code{package}
2248 declarations (@pxref{Defining Packages}).
2250 @deftp {Data Type} package
2251 This is the data type representing a package recipe.
2255 The name of the package, as a string.
2257 @item @code{version}
2258 The version of the package, as a string.
2261 An origin object telling how the source code for the package should be
2262 acquired (@pxref{origin Reference}).
2264 @item @code{build-system}
2265 The build system that should be used to build the package (@pxref{Build
2268 @item @code{arguments} (default: @code{'()})
2269 The arguments that should be passed to the build system. This is a
2270 list, typically containing sequential keyword-value pairs.
2272 @item @code{inputs} (default: @code{'()})
2273 @itemx @code{native-inputs} (default: @code{'()})
2274 @itemx @code{propagated-inputs} (default: @code{'()})
2275 @cindex inputs, of packages
2276 These fields list dependencies of the package. Each one is a list of
2277 tuples, where each tuple has a label for the input (a string) as its
2278 first element, a package, origin, or derivation as its second element,
2279 and optionally the name of the output thereof that should be used, which
2280 defaults to @code{"out"} (@pxref{Packages with Multiple Outputs}, for
2281 more on package outputs). For example, the list below specifies 3
2285 `(("libffi" ,libffi)
2286 ("libunistring" ,libunistring)
2287 ("glib:bin" ,glib "bin")) ;the "bin" output of Glib
2290 @cindex cross compilation, package dependencies
2291 The distinction between @code{native-inputs} and @code{inputs} is
2292 necessary when considering cross-compilation. When cross-compiling,
2293 dependencies listed in @code{inputs} are built for the @emph{target}
2294 architecture; conversely, dependencies listed in @code{native-inputs}
2295 are built for the architecture of the @emph{build} machine.
2297 @code{native-inputs} is typically where you would list tools needed at
2298 build time but not at run time, such as Autoconf, Automake, pkg-config,
2299 Gettext, or Bison. @command{guix lint} can report likely mistakes in
2300 this area (@pxref{Invoking guix lint}).
2302 @anchor{package-propagated-inputs}
2303 Lastly, @code{propagated-inputs} is similar to @code{inputs}, but the
2304 specified packages will be force-installed alongside the package they
2305 belong to (@pxref{package-cmd-propagated-inputs, @command{guix
2306 package}}, for information on how @command{guix package} deals with
2309 For example this is necessary when a C/C++ library needs headers of
2310 another library to compile, or when a pkg-config file refers to another
2311 one @i{via} its @code{Requires} field.
2313 Another example where @code{propagated-inputs} is useful is for
2314 languages that lack a facility to record the run-time search path akin
2315 to ELF's @code{RUNPATH}; this includes Guile, Python, Perl, GHC, and
2316 more. To ensure that libraries written in those languages can find
2317 library code they depend on at run time, run-time dependencies must be
2318 listed in @code{propagated-inputs} rather than @code{inputs}.
2320 @item @code{self-native-input?} (default: @code{#f})
2321 This is a Boolean field telling whether the package should use itself as
2322 a native input when cross-compiling.
2324 @item @code{outputs} (default: @code{'("out")})
2325 The list of output names of the package. @xref{Packages with Multiple
2326 Outputs}, for typical uses of additional outputs.
2328 @item @code{native-search-paths} (default: @code{'()})
2329 @itemx @code{search-paths} (default: @code{'()})
2330 A list of @code{search-path-specification} objects describing
2331 search-path environment variables honored by the package.
2333 @item @code{replacement} (default: @code{#f})
2334 This must either @code{#f} or a package object that will be used as a
2335 @dfn{replacement} for this package. @xref{Security Updates, grafts},
2338 @item @code{synopsis}
2339 A one-line description of the package.
2341 @item @code{description}
2342 A more elaborate description of the package.
2344 @item @code{license}
2345 The license of the package; a value from @code{(guix licenses)}.
2347 @item @code{home-page}
2348 The URL to the home-page of the package, as a string.
2350 @item @code{supported-systems} (default: @var{%supported-systems})
2351 The list of systems supported by the package, as strings of the form
2352 @code{architecture-kernel}, for example @code{"x86_64-linux"}.
2354 @item @code{maintainers} (default: @code{'()})
2355 The list of maintainers of the package, as @code{maintainer} objects.
2357 @item @code{location} (default: source location of the @code{package} form)
2358 The source location of the package. It's useful to override this when
2359 inheriting from another package, in which case this field is not
2360 automatically corrected.
2365 @node origin Reference
2366 @subsection @code{origin} Reference
2368 This section summarizes all the options available in @code{origin}
2369 declarations (@pxref{Defining Packages}).
2371 @deftp {Data Type} origin
2372 This is the data type representing a source code origin.
2376 An object containing the URI of the source. The object type depends on
2377 the @code{method} (see below). For example, when using the
2378 @var{url-fetch} method of @code{(guix download)}, the valid @code{uri}
2379 values are: a URL represented as a string, or a list thereof.
2382 A procedure that will handle the URI.
2387 @item @var{url-fetch} from @code{(guix download)}
2388 download a file the HTTP, HTTPS, or FTP URL specified in the
2391 @item @var{git-fetch} from @code{(guix git-download)}
2392 clone the Git version control repository, and check out the revision
2393 specified in the @code{uri} field as a @code{git-reference} object; a
2394 @code{git-reference} looks like this:
2398 (url "git://git.debian.org/git/pkg-shadow/shadow")
2399 (commit "v4.1.5.1"))
2404 A bytevector containing the SHA-256 hash of the source. Typically the
2405 @code{base32} form is used here to generate the bytevector from a
2408 @item @code{file-name} (default: @code{#f})
2409 The file name under which the source code should be saved. When this is
2410 @code{#f}, a sensible default value will be used in most cases. In case
2411 the source is fetched from a URL, the file name from the URL will be
2412 used. For version control checkouts, it's recommended to provide the
2413 file name explicitly because the default is not very descriptive.
2415 @item @code{patches} (default: @code{'()})
2416 A list of file names containing patches to be applied to the source.
2418 @item @code{snippet} (default: @code{#f})
2419 A quoted piece of code that will be run in the source directory to make
2420 any modifications, which is sometimes more convenient than a patch.
2422 @item @code{patch-flags} (default: @code{'("-p1")})
2423 A list of command-line flags that should be passed to the @code{patch}
2426 @item @code{patch-inputs} (default: @code{#f})
2427 Input packages or derivations to the patching process. When this is
2428 @code{#f}, the usual set of inputs necessary for patching are provided,
2429 such as GNU@tie{}Patch.
2431 @item @code{modules} (default: @code{'()})
2432 A list of Guile modules that should be loaded during the patching
2433 process and while running the code in the @code{snippet} field.
2435 @item @code{imported-modules} (default: @code{'()})
2436 The list of Guile modules to import in the patch derivation, for use by
2439 @item @code{patch-guile} (default: @code{#f})
2440 The Guile package that should be used in the patching process. When
2441 this is @code{#f}, a sensible default is used.
2447 @section Build Systems
2449 @cindex build system
2450 Each package definition specifies a @dfn{build system} and arguments for
2451 that build system (@pxref{Defining Packages}). This @code{build-system}
2452 field represents the build procedure of the package, as well implicit
2453 dependencies of that build procedure.
2455 Build systems are @code{<build-system>} objects. The interface to
2456 create and manipulate them is provided by the @code{(guix build-system)}
2457 module, and actual build systems are exported by specific modules.
2459 @cindex bag (low-level package representation)
2460 Under the hood, build systems first compile package objects to
2461 @dfn{bags}. A @dfn{bag} is like a package, but with less
2462 ornamentation---in other words, a bag is a lower-level representation of
2463 a package, which includes all the inputs of that package, including some
2464 that were implicitly added by the build system. This intermediate
2465 representation is then compiled to a derivation (@pxref{Derivations}).
2467 Build systems accept an optional list of @dfn{arguments}. In package
2468 definitions, these are passed @i{via} the @code{arguments} field
2469 (@pxref{Defining Packages}). They are typically keyword arguments
2470 (@pxref{Optional Arguments, keyword arguments in Guile,, guile, GNU
2471 Guile Reference Manual}). The value of these arguments is usually
2472 evaluated in the @dfn{build stratum}---i.e., by a Guile process launched
2473 by the daemon (@pxref{Derivations}).
2475 The main build system is @var{gnu-build-system}, which implements the
2476 standard build procedure for GNU packages and many other packages. It
2477 is provided by the @code{(guix build-system gnu)} module.
2479 @defvr {Scheme Variable} gnu-build-system
2480 @var{gnu-build-system} represents the GNU Build System, and variants
2481 thereof (@pxref{Configuration, configuration and makefile conventions,,
2482 standards, GNU Coding Standards}).
2484 @cindex build phases
2485 In a nutshell, packages using it configured, built, and installed with
2486 the usual @code{./configure && make && make check && make install}
2487 command sequence. In practice, a few additional steps are often needed.
2488 All these steps are split up in separate @dfn{phases},
2489 notably@footnote{Please see the @code{(guix build gnu-build-system)}
2490 modules for more details about the build phases.}:
2494 Unpack the source tarball, and change the current directory to the
2495 extracted source tree. If the source is actually a directory, copy it
2496 to the build tree, and enter that directory.
2498 @item patch-source-shebangs
2499 Patch shebangs encountered in source files so they refer to the right
2500 store file names. For instance, this changes @code{#!/bin/sh} to
2501 @code{#!/gnu/store/@dots{}-bash-4.3/bin/sh}.
2504 Run the @file{configure} script with a number of default options, such
2505 as @code{--prefix=/gnu/store/@dots{}}, as well as the options specified
2506 by the @code{#:configure-flags} argument.
2509 Run @code{make} with the list of flags specified with
2510 @code{#:make-flags}. If the @code{#:parallel-builds?} argument is true
2511 (the default), build with @code{make -j}.
2514 Run @code{make check}, or some other target specified with
2515 @code{#:test-target}, unless @code{#:tests? #f} is passed. If the
2516 @code{#:parallel-tests?} argument is true (the default), run @code{make
2520 Run @code{make install} with the flags listed in @code{#:make-flags}.
2522 @item patch-shebangs
2523 Patch shebangs on the installed executable files.
2526 Strip debugging symbols from ELF files (unless @code{#:strip-binaries?}
2527 is false), copying them to the @code{debug} output when available
2528 (@pxref{Installing Debugging Files}).
2531 @vindex %standard-phases
2532 The build-side module @code{(guix build gnu-build-system)} defines
2533 @var{%standard-phases} as the default list of build phases.
2534 @var{%standard-phases} is a list of symbol/procedure pairs, where the
2535 procedure implements the actual phase.
2537 The list of phases used for a particular package can be changed with the
2538 @code{#:phases} parameter. For instance, passing:
2541 #:phases (alist-delete 'configure %standard-phases)
2544 means that all the phases described above will be used, except the
2545 @code{configure} phase.
2547 In addition, this build system ensures that the ``standard'' environment
2548 for GNU packages is available. This includes tools such as GCC, libc,
2549 Coreutils, Bash, Make, Diffutils, grep, and sed (see the @code{(guix
2550 build-system gnu)} module for a complete list.) We call these the
2551 @dfn{implicit inputs} of a package, because package definitions don't
2552 have to mention them.
2555 Other @code{<build-system>} objects are defined to support other
2556 conventions and tools used by free software packages. They inherit most
2557 of @var{gnu-build-system}, and differ mainly in the set of inputs
2558 implicitly added to the build process, and in the list of phases
2559 executed. Some of these build systems are listed below.
2561 @defvr {Scheme Variable} cmake-build-system
2562 This variable is exported by @code{(guix build-system cmake)}. It
2563 implements the build procedure for packages using the
2564 @url{http://www.cmake.org, CMake build tool}.
2566 It automatically adds the @code{cmake} package to the set of inputs.
2567 Which package is used can be specified with the @code{#:cmake}
2570 The @code{#:configure-flags} parameter is taken as a list of flags
2571 passed to the @command{cmake} command. The @code{#:build-type}
2572 parameter specifies in abstract terms the flags passed to the compiler;
2573 it defaults to @code{"RelWithDebInfo"} (short for ``release mode with
2574 debugging information''), which roughly means that code is compiled with
2575 @code{-O2 -g}, as is the case for Autoconf-based packages by default.
2578 @defvr {Scheme Variable} glib-or-gtk-build-system
2579 This variable is exported by @code{(guix build-system glib-or-gtk)}. It
2580 is intended for use with packages making use of GLib or GTK+.
2582 This build system adds the following two phases to the ones defined by
2583 @var{gnu-build-system}:
2586 @item glib-or-gtk-wrap
2587 The phase @code{glib-or-gtk-wrap} ensures that programs found under
2588 @file{bin/} are able to find GLib's ``schemas'' and
2589 @uref{https://developer.gnome.org/gtk3/stable/gtk-running.html, GTK+
2590 modules}. This is achieved by wrapping the programs in launch scripts
2591 that appropriately set the @code{XDG_DATA_DIRS} and @code{GTK_PATH}
2592 environment variables.
2594 It is possible to exclude specific package outputs from that wrapping
2595 process by listing their names in the
2596 @code{#:glib-or-gtk-wrap-excluded-outputs} parameter. This is useful
2597 when an output is known not to contain any GLib or GTK+ binaries, and
2598 where wrapping would gratuitously add a dependency of that output on
2601 @item glib-or-gtk-compile-schemas
2602 The phase @code{glib-or-gtk-compile-schemas} makes sure that all GLib's
2603 @uref{https://developer.gnome.org/gio/stable/glib-compile-schemas.html,
2604 GSettings schemas} are compiled. Compilation is performed by the
2605 @command{glib-compile-schemas} program. It is provided by the package
2606 @code{glib:bin} which is automatically imported by the build system.
2607 The @code{glib} package providing @command{glib-compile-schemas} can be
2608 specified with the @code{#:glib} parameter.
2611 Both phases are executed after the @code{install} phase.
2614 @defvr {Scheme Variable} python-build-system
2615 This variable is exported by @code{(guix build-system python)}. It
2616 implements the more or less standard build procedure used by Python
2617 packages, which consists in running @code{python setup.py build} and
2618 then @code{python setup.py install --prefix=/gnu/store/@dots{}}.
2620 For packages that install stand-alone Python programs under @code{bin/},
2621 it takes care of wrapping these programs so their @code{PYTHONPATH}
2622 environment variable points to all the Python libraries they depend on.
2624 Which Python package is used can be specified with the @code{#:python}
2628 @defvr {Scheme Variable} perl-build-system
2629 This variable is exported by @code{(guix build-system perl)}. It
2630 implements the standard build procedure for Perl packages, which either
2631 consists in running @code{perl Build.PL --prefix=/gnu/store/@dots{}},
2632 followed by @code{Build} and @code{Build install}; or in running
2633 @code{perl Makefile.PL PREFIX=/gnu/store/@dots{}}, followed by
2634 @code{make} and @code{make install}; depending on which of
2635 @code{Build.PL} or @code{Makefile.PL} is present in the package
2636 distribution. Preference is given to the former if both @code{Build.PL}
2637 and @code{Makefile.PL} exist in the package distribution. This
2638 preference can be reversed by specifying @code{#t} for the
2639 @code{#:make-maker?} parameter.
2641 The initial @code{perl Makefile.PL} or @code{perl Build.PL} invocation
2642 passes flags specified by the @code{#:make-maker-flags} or
2643 @code{#:module-build-flags} parameter, respectively.
2645 Which Perl package is used can be specified with @code{#:perl}.
2648 @defvr {Scheme Variable} r-build-system
2649 This variable is exported by @code{(guix build-system r)}. It
2650 implements the build procedure used by @uref{http://r-project.org, R}
2651 packages, which essentially is little more than running @code{R CMD
2652 INSTALL --library=/gnu/store/@dots{}} in an environment where
2653 @code{R_LIBS_SITE} contains the paths to all R package inputs. Tests
2654 are run after installation using the R function
2655 @code{tools::testInstalledPackage}.
2658 @defvr {Scheme Variable} ruby-build-system
2659 This variable is exported by @code{(guix build-system ruby)}. It
2660 implements the RubyGems build procedure used by Ruby packages, which
2661 involves running @code{gem build} followed by @code{gem install}.
2663 The @code{source} field of a package that uses this build system
2664 typically references a gem archive, since this is the format that Ruby
2665 developers use when releasing their software. The build system unpacks
2666 the gem archive, potentially patches the source, runs the test suite,
2667 repackages the gem, and installs it. Additionally, directories and
2668 tarballs may be referenced to allow building unreleased gems from Git or
2669 a traditional source release tarball.
2671 Which Ruby package is used can be specified with the @code{#:ruby}
2672 parameter. A list of additional flags to be passed to the @command{gem}
2673 command can be specified with the @code{#:gem-flags} parameter.
2676 @defvr {Scheme Variable} waf-build-system
2677 This variable is exported by @code{(guix build-system waf)}. It
2678 implements a build procedure around the @code{waf} script. The common
2679 phases---@code{configure}, @code{build}, and @code{install}---are
2680 implemented by passing their names as arguments to the @code{waf}
2683 The @code{waf} script is executed by the Python interpreter. Which
2684 Python package is used to run the script can be specified with the
2685 @code{#:python} parameter.
2688 @defvr {Scheme Variable} haskell-build-system
2689 This variable is exported by @code{(guix build-system haskell)}. It
2690 implements the Cabal build procedure used by Haskell packages, which
2691 involves running @code{runhaskell Setup.hs configure
2692 --prefix=/gnu/store/@dots{}} and @code{runhaskell Setup.hs build}.
2693 Instead of installing the package by running @code{runhaskell Setup.hs
2694 install}, to avoid trying to register libraries in the read-only
2695 compiler store directory, the build system uses @code{runhaskell
2696 Setup.hs copy}, followed by @code{runhaskell Setup.hs register}. In
2697 addition, the build system generates the package documentation by
2698 running @code{runhaskell Setup.hs haddock}, unless @code{#:haddock? #f}
2699 is passed. Optional Haddock parameters can be passed with the help of
2700 the @code{#:haddock-flags} parameter. If the file @code{Setup.hs} is
2701 not found, the build system looks for @code{Setup.lhs} instead.
2703 Which Haskell compiler is used can be specified with the @code{#:haskell}
2704 parameter which defaults to @code{ghc}.
2707 @defvr {Scheme Variable} emacs-build-system
2708 This variable is exported by @code{(guix build-system emacs)}. It
2709 implements an installation procedure similar to the one of Emacs' own
2710 packaging system (@pxref{Packages,,, emacs, The GNU Emacs Manual}).
2712 It first creates the @code{@var{package}-autoloads.el} file, then it
2713 byte compiles all Emacs Lisp files. Differently from the Emacs
2714 packaging system, the Info documentation files are moved to the standard
2715 documentation directory and the @file{dir} file is deleted. Each
2716 package is installed in its own directory under
2717 @file{share/emacs/site-lisp/guix.d}.
2720 Lastly, for packages that do not need anything as sophisticated, a
2721 ``trivial'' build system is provided. It is trivial in the sense that
2722 it provides basically no support: it does not pull any implicit inputs,
2723 and does not have a notion of build phases.
2725 @defvr {Scheme Variable} trivial-build-system
2726 This variable is exported by @code{(guix build-system trivial)}.
2728 This build system requires a @code{#:builder} argument. This argument
2729 must be a Scheme expression that builds the package's output(s)---as
2730 with @code{build-expression->derivation} (@pxref{Derivations,
2731 @code{build-expression->derivation}}).
2740 Conceptually, the @dfn{store} is where derivations that have been
2741 successfully built are stored---by default, under @file{/gnu/store}.
2742 Sub-directories in the store are referred to as @dfn{store paths}. The
2743 store has an associated database that contains information such as the
2744 store paths referred to by each store path, and the list of @emph{valid}
2745 store paths---paths that result from a successful build.
2747 The store is always accessed by the daemon on behalf of its clients
2748 (@pxref{Invoking guix-daemon}). To manipulate the store, clients
2749 connect to the daemon over a Unix-domain socket, send it requests, and
2750 read the result---these are remote procedure calls, or RPCs.
2752 The @code{(guix store)} module provides procedures to connect to the
2753 daemon, and to perform RPCs. These are described below.
2755 @deffn {Scheme Procedure} open-connection [@var{file}] [#:reserve-space? #t]
2756 Connect to the daemon over the Unix-domain socket at @var{file}. When
2757 @var{reserve-space?} is true, instruct it to reserve a little bit of
2758 extra space on the file system so that the garbage collector can still
2759 operate, should the disk become full. Return a server object.
2761 @var{file} defaults to @var{%default-socket-path}, which is the normal
2762 location given the options that were passed to @command{configure}.
2765 @deffn {Scheme Procedure} close-connection @var{server}
2766 Close the connection to @var{server}.
2769 @defvr {Scheme Variable} current-build-output-port
2770 This variable is bound to a SRFI-39 parameter, which refers to the port
2771 where build and error logs sent by the daemon should be written.
2774 Procedures that make RPCs all take a server object as their first
2777 @deffn {Scheme Procedure} valid-path? @var{server} @var{path}
2778 Return @code{#t} when @var{path} is a valid store path.
2781 @deffn {Scheme Procedure} add-text-to-store @var{server} @var{name} @var{text} [@var{references}]
2782 Add @var{text} under file @var{name} in the store, and return its store
2783 path. @var{references} is the list of store paths referred to by the
2784 resulting store path.
2787 @deffn {Scheme Procedure} build-derivations @var{server} @var{derivations}
2788 Build @var{derivations} (a list of @code{<derivation>} objects or
2789 derivation paths), and return when the worker is done building them.
2790 Return @code{#t} on success.
2793 Note that the @code{(guix monads)} module provides a monad as well as
2794 monadic versions of the above procedures, with the goal of making it
2795 more convenient to work with code that accesses the store (@pxref{The
2799 @i{This section is currently incomplete.}
2802 @section Derivations
2805 Low-level build actions and the environment in which they are performed
2806 are represented by @dfn{derivations}. A derivation contain the
2807 following pieces of information:
2811 The outputs of the derivation---derivations produce at least one file or
2812 directory in the store, but may produce more.
2815 The inputs of the derivations, which may be other derivations or plain
2816 files in the store (patches, build scripts, etc.)
2819 The system type targeted by the derivation---e.g., @code{x86_64-linux}.
2822 The file name of a build script in the store, along with the arguments
2826 A list of environment variables to be defined.
2830 @cindex derivation path
2831 Derivations allow clients of the daemon to communicate build actions to
2832 the store. They exist in two forms: as an in-memory representation,
2833 both on the client- and daemon-side, and as files in the store whose
2834 name end in @code{.drv}---these files are referred to as @dfn{derivation
2835 paths}. Derivations paths can be passed to the @code{build-derivations}
2836 procedure to perform the build actions they prescribe (@pxref{The
2839 The @code{(guix derivations)} module provides a representation of
2840 derivations as Scheme objects, along with procedures to create and
2841 otherwise manipulate derivations. The lowest-level primitive to create
2842 a derivation is the @code{derivation} procedure:
2844 @deffn {Scheme Procedure} derivation @var{store} @var{name} @var{builder} @
2845 @var{args} [#:outputs '("out")] [#:hash #f] [#:hash-algo #f] @
2846 [#:recursive? #f] [#:inputs '()] [#:env-vars '()] @
2847 [#:system (%current-system)] [#:references-graphs #f] @
2848 [#:allowed-references #f] [#:leaked-env-vars #f] [#:local-build? #f] @
2849 [#:substitutable? #t]
2850 Build a derivation with the given arguments, and return the resulting
2851 @code{<derivation>} object.
2853 When @var{hash} and @var{hash-algo} are given, a
2854 @dfn{fixed-output derivation} is created---i.e., one whose result is
2855 known in advance, such as a file download. If, in addition,
2856 @var{recursive?} is true, then that fixed output may be an executable
2857 file or a directory and @var{hash} must be the hash of an archive
2858 containing this output.
2860 When @var{references-graphs} is true, it must be a list of file
2861 name/store path pairs. In that case, the reference graph of each store
2862 path is exported in the build environment in the corresponding file, in
2863 a simple text format.
2865 When @var{allowed-references} is true, it must be a list of store items
2866 or outputs that the derivation's output may refer to.
2868 When @var{leaked-env-vars} is true, it must be a list of strings
2869 denoting environment variables that are allowed to ``leak'' from the
2870 daemon's environment to the build environment. This is only applicable
2871 to fixed-output derivations---i.e., when @var{hash} is true. The main
2872 use is to allow variables such as @code{http_proxy} to be passed to
2873 derivations that download files.
2875 When @var{local-build?} is true, declare that the derivation is not a
2876 good candidate for offloading and should rather be built locally
2877 (@pxref{Daemon Offload Setup}). This is the case for small derivations
2878 where the costs of data transfers would outweigh the benefits.
2880 When @var{substitutable?} is false, declare that substitutes of the
2881 derivation's output should not be used (@pxref{Substitutes}). This is
2882 useful, for instance, when building packages that capture details of the
2883 host CPU instruction set.
2887 Here's an example with a shell script as its builder, assuming
2888 @var{store} is an open connection to the daemon, and @var{bash} points
2889 to a Bash executable in the store:
2892 (use-modules (guix utils)
2896 (let ((builder ; add the Bash script to the store
2897 (add-text-to-store store "my-builder.sh"
2898 "echo hello world > $out\n" '())))
2899 (derivation store "foo"
2900 bash `("-e" ,builder)
2901 #:inputs `((,bash) (,builder))
2902 #:env-vars '(("HOME" . "/homeless"))))
2903 @result{} #<derivation /gnu/store/@dots{}-foo.drv => /gnu/store/@dots{}-foo>
2906 As can be guessed, this primitive is cumbersome to use directly. A
2907 better approach is to write build scripts in Scheme, of course! The
2908 best course of action for that is to write the build code as a
2909 ``G-expression'', and to pass it to @code{gexp->derivation}. For more
2910 information, @pxref{G-Expressions}.
2912 Once upon a time, @code{gexp->derivation} did not exist and constructing
2913 derivations with build code written in Scheme was achieved with
2914 @code{build-expression->derivation}, documented below. This procedure
2915 is now deprecated in favor of the much nicer @code{gexp->derivation}.
2917 @deffn {Scheme Procedure} build-expression->derivation @var{store} @
2918 @var{name} @var{exp} @
2919 [#:system (%current-system)] [#:inputs '()] @
2920 [#:outputs '("out")] [#:hash #f] [#:hash-algo #f] @
2921 [#:recursive? #f] [#:env-vars '()] [#:modules '()] @
2922 [#:references-graphs #f] [#:allowed-references #f] @
2923 [#:local-build? #f] [#:substitutable? #t] [#:guile-for-build #f]
2924 Return a derivation that executes Scheme expression @var{exp} as a
2925 builder for derivation @var{name}. @var{inputs} must be a list of
2926 @code{(name drv-path sub-drv)} tuples; when @var{sub-drv} is omitted,
2927 @code{"out"} is assumed. @var{modules} is a list of names of Guile
2928 modules from the current search path to be copied in the store,
2929 compiled, and made available in the load path during the execution of
2930 @var{exp}---e.g., @code{((guix build utils) (guix build
2931 gnu-build-system))}.
2933 @var{exp} is evaluated in an environment where @code{%outputs} is bound
2934 to a list of output/path pairs, and where @code{%build-inputs} is bound
2935 to a list of string/output-path pairs made from @var{inputs}.
2936 Optionally, @var{env-vars} is a list of string pairs specifying the name
2937 and value of environment variables visible to the builder. The builder
2938 terminates by passing the result of @var{exp} to @code{exit}; thus, when
2939 @var{exp} returns @code{#f}, the build is considered to have failed.
2941 @var{exp} is built using @var{guile-for-build} (a derivation). When
2942 @var{guile-for-build} is omitted or is @code{#f}, the value of the
2943 @code{%guile-for-build} fluid is used instead.
2945 See the @code{derivation} procedure for the meaning of
2946 @var{references-graphs}, @var{allowed-references}, @var{local-build?},
2947 and @var{substitutable?}.
2951 Here's an example of a single-output derivation that creates a directory
2952 containing one file:
2955 (let ((builder '(let ((out (assoc-ref %outputs "out")))
2956 (mkdir out) ; create /gnu/store/@dots{}-goo
2957 (call-with-output-file (string-append out "/test")
2959 (display '(hello guix) p))))))
2960 (build-expression->derivation store "goo" builder))
2962 @result{} #<derivation /gnu/store/@dots{}-goo.drv => @dots{}>
2966 @node The Store Monad
2967 @section The Store Monad
2971 The procedures that operate on the store described in the previous
2972 sections all take an open connection to the build daemon as their first
2973 argument. Although the underlying model is functional, they either have
2974 side effects or depend on the current state of the store.
2976 The former is inconvenient: the connection to the build daemon has to be
2977 carried around in all those functions, making it impossible to compose
2978 functions that do not take that parameter with functions that do. The
2979 latter can be problematic: since store operations have side effects
2980 and/or depend on external state, they have to be properly sequenced.
2982 @cindex monadic values
2983 @cindex monadic functions
2984 This is where the @code{(guix monads)} module comes in. This module
2985 provides a framework for working with @dfn{monads}, and a particularly
2986 useful monad for our uses, the @dfn{store monad}. Monads are a
2987 construct that allows two things: associating ``context'' with values
2988 (in our case, the context is the store), and building sequences of
2989 computations (here computations include accesses to the store.) Values
2990 in a monad---values that carry this additional context---are called
2991 @dfn{monadic values}; procedures that return such values are called
2992 @dfn{monadic procedures}.
2994 Consider this ``normal'' procedure:
2997 (define (sh-symlink store)
2998 ;; Return a derivation that symlinks the 'bash' executable.
2999 (let* ((drv (package-derivation store bash))
3000 (out (derivation->output-path drv))
3001 (sh (string-append out "/bin/bash")))
3002 (build-expression->derivation store "sh"
3003 `(symlink ,sh %output))))
3006 Using @code{(guix monads)} and @code{(guix gexp)}, it may be rewritten
3007 as a monadic function:
3010 (define (sh-symlink)
3011 ;; Same, but return a monadic value.
3012 (mlet %store-monad ((drv (package->derivation bash)))
3013 (gexp->derivation "sh"
3014 #~(symlink (string-append #$drv "/bin/bash")
3018 There several things to note in the second version: the @code{store}
3019 parameter is now implicit and is ``threaded'' in the calls to the
3020 @code{package->derivation} and @code{gexp->derivation} monadic
3021 procedures, and the monadic value returned by @code{package->derivation}
3022 is @dfn{bound} using @code{mlet} instead of plain @code{let}.
3024 As it turns out, the call to @code{package->derivation} can even be
3025 omitted since it will take place implicitly, as we will see later
3026 (@pxref{G-Expressions}):
3029 (define (sh-symlink)
3030 (gexp->derivation "sh"
3031 #~(symlink (string-append #$bash "/bin/bash")
3036 @c <https://syntaxexclamation.wordpress.com/2014/06/26/escaping-continuations/>
3037 @c for the funny quote.
3038 Calling the monadic @code{sh-symlink} has no effect. As someone once
3039 said, ``you exit a monad like you exit a building on fire: by running''.
3040 So, to exit the monad and get the desired effect, one must use
3041 @code{run-with-store}:
3044 (run-with-store (open-connection) (sh-symlink))
3045 @result{} /gnu/store/...-sh-symlink
3048 Note that the @code{(guix monad-repl)} module extends Guile's REPL with
3049 new ``meta-commands'' to make it easier to deal with monadic procedures:
3050 @code{run-in-store}, and @code{enter-store-monad}. The former, is used
3051 to ``run'' a single monadic value through the store:
3054 scheme@@(guile-user)> ,run-in-store (package->derivation hello)
3055 $1 = #<derivation /gnu/store/@dots{}-hello-2.9.drv => @dots{}>
3058 The latter enters a recursive REPL, where all the return values are
3059 automatically run through the store:
3062 scheme@@(guile-user)> ,enter-store-monad
3063 store-monad@@(guile-user) [1]> (package->derivation hello)
3064 $2 = #<derivation /gnu/store/@dots{}-hello-2.9.drv => @dots{}>
3065 store-monad@@(guile-user) [1]> (text-file "foo" "Hello!")
3066 $3 = "/gnu/store/@dots{}-foo"
3067 store-monad@@(guile-user) [1]> ,q
3068 scheme@@(guile-user)>
3072 Note that non-monadic values cannot be returned in the
3073 @code{store-monad} REPL.
3075 The main syntactic forms to deal with monads in general are provided by
3076 the @code{(guix monads)} module and are described below.
3078 @deffn {Scheme Syntax} with-monad @var{monad} @var{body} ...
3079 Evaluate any @code{>>=} or @code{return} forms in @var{body} as being
3083 @deffn {Scheme Syntax} return @var{val}
3084 Return a monadic value that encapsulates @var{val}.
3087 @deffn {Scheme Syntax} >>= @var{mval} @var{mproc} ...
3088 @dfn{Bind} monadic value @var{mval}, passing its ``contents'' to monadic
3089 procedures @var{mproc}@dots{}@footnote{This operation is commonly
3090 referred to as ``bind'', but that name denotes an unrelated procedure in
3091 Guile. Thus we use this somewhat cryptic symbol inherited from the
3092 Haskell language.}. There can be one @var{mproc} or several of them, as
3097 (with-monad %state-monad
3099 (lambda (x) (return (+ 1 x)))
3100 (lambda (x) (return (* 2 x)))))
3104 @result{} some-state
3108 @deffn {Scheme Syntax} mlet @var{monad} ((@var{var} @var{mval}) ...) @
3110 @deffnx {Scheme Syntax} mlet* @var{monad} ((@var{var} @var{mval}) ...) @
3112 Bind the variables @var{var} to the monadic values @var{mval} in
3113 @var{body}. The form (@var{var} -> @var{val}) binds @var{var} to the
3114 ``normal'' value @var{val}, as per @code{let}.
3116 @code{mlet*} is to @code{mlet} what @code{let*} is to @code{let}
3117 (@pxref{Local Bindings,,, guile, GNU Guile Reference Manual}).
3120 @deffn {Scheme System} mbegin @var{monad} @var{mexp} ...
3121 Bind @var{mexp} and the following monadic expressions in sequence,
3122 returning the result of the last expression.
3124 This is akin to @code{mlet}, except that the return values of the
3125 monadic expressions are ignored. In that sense, it is analogous to
3126 @code{begin}, but applied to monadic expressions.
3130 The @code{(guix monads)} module provides the @dfn{state monad}, which
3131 allows an additional value---the state---to be @emph{threaded} through
3132 monadic procedure calls.
3134 @defvr {Scheme Variable} %state-monad
3135 The state monad. Procedures in the state monad can access and change
3136 the state that is threaded.
3138 Consider the example below. The @code{square} procedure returns a value
3139 in the state monad. It returns the square of its argument, but also
3140 increments the current state value:
3144 (mlet %state-monad ((count (current-state)))
3145 (mbegin %state-monad
3146 (set-current-state (+ 1 count))
3149 (run-with-state (sequence %state-monad (map square (iota 3))) 0)
3154 When ``run'' through @var{%state-monad}, we obtain that additional state
3155 value, which is the number of @code{square} calls.
3158 @deffn {Monadic Procedure} current-state
3159 Return the current state as a monadic value.
3162 @deffn {Monadic Procedure} set-current-state @var{value}
3163 Set the current state to @var{value} and return the previous state as a
3167 @deffn {Monadic Procedure} state-push @var{value}
3168 Push @var{value} to the current state, which is assumed to be a list,
3169 and return the previous state as a monadic value.
3172 @deffn {Monadic Procedure} state-pop
3173 Pop a value from the current state and return it as a monadic value.
3174 The state is assumed to be a list.
3177 @deffn {Scheme Procedure} run-with-state @var{mval} [@var{state}]
3178 Run monadic value @var{mval} starting with @var{state} as the initial
3179 state. Return two values: the resulting value, and the resulting state.
3182 The main interface to the store monad, provided by the @code{(guix
3183 store)} module, is as follows.
3185 @defvr {Scheme Variable} %store-monad
3186 The store monad---an alias for @var{%state-monad}.
3188 Values in the store monad encapsulate accesses to the store. When its
3189 effect is needed, a value of the store monad must be ``evaluated'' by
3190 passing it to the @code{run-with-store} procedure (see below.)
3193 @deffn {Scheme Procedure} run-with-store @var{store} @var{mval} [#:guile-for-build] [#:system (%current-system)]
3194 Run @var{mval}, a monadic value in the store monad, in @var{store}, an
3195 open store connection.
3198 @deffn {Monadic Procedure} text-file @var{name} @var{text} [@var{references}]
3199 Return as a monadic value the absolute file name in the store of the file
3200 containing @var{text}, a string. @var{references} is a list of store items that the
3201 resulting text file refers to; it defaults to the empty list.
3204 @deffn {Monadic Procedure} interned-file @var{file} [@var{name}] @
3206 Return the name of @var{file} once interned in the store. Use
3207 @var{name} as its store name, or the basename of @var{file} if
3208 @var{name} is omitted.
3210 When @var{recursive?} is true, the contents of @var{file} are added
3211 recursively; if @var{file} designates a flat file and @var{recursive?}
3212 is true, its contents are added, and its permission bits are kept.
3214 The example below adds a file to the store, under two different names:
3217 (run-with-store (open-connection)
3218 (mlet %store-monad ((a (interned-file "README"))
3219 (b (interned-file "README" "LEGU-MIN")))
3220 (return (list a b))))
3222 @result{} ("/gnu/store/rwm@dots{}-README" "/gnu/store/44i@dots{}-LEGU-MIN")
3227 The @code{(guix packages)} module exports the following package-related
3230 @deffn {Monadic Procedure} package-file @var{package} [@var{file}] @
3231 [#:system (%current-system)] [#:target #f] @
3232 [#:output "out"] Return as a monadic
3233 value in the absolute file name of @var{file} within the @var{output}
3234 directory of @var{package}. When @var{file} is omitted, return the name
3235 of the @var{output} directory of @var{package}. When @var{target} is
3236 true, use it as a cross-compilation target triplet.
3239 @deffn {Monadic Procedure} package->derivation @var{package} [@var{system}]
3240 @deffnx {Monadic Procedure} package->cross-derivation @var{package} @
3241 @var{target} [@var{system}]
3242 Monadic version of @code{package-derivation} and
3243 @code{package-cross-derivation} (@pxref{Defining Packages}).
3248 @section G-Expressions
3250 @cindex G-expression
3251 @cindex build code quoting
3252 So we have ``derivations'', which represent a sequence of build actions
3253 to be performed to produce an item in the store (@pxref{Derivations}).
3254 Those build actions are performed when asking the daemon to actually
3255 build the derivations; they are run by the daemon in a container
3256 (@pxref{Invoking guix-daemon}).
3258 @cindex strata of code
3259 It should come as no surprise that we like to write those build actions
3260 in Scheme. When we do that, we end up with two @dfn{strata} of Scheme
3261 code@footnote{The term @dfn{stratum} in this context was coined by
3262 Manuel Serrano et al.@: in the context of their work on Hop. Oleg
3263 Kiselyov, who has written insightful
3264 @url{http://okmij.org/ftp/meta-programming/#meta-scheme, essays and code
3265 on this topic}, refers to this kind of code generation as
3266 @dfn{staging}.}: the ``host code''---code that defines packages, talks
3267 to the daemon, etc.---and the ``build code''---code that actually
3268 performs build actions, such as making directories, invoking
3269 @command{make}, etc.
3271 To describe a derivation and its build actions, one typically needs to
3272 embed build code inside host code. It boils down to manipulating build
3273 code as data, and Scheme's homoiconicity---code has a direct
3274 representation as data---comes in handy for that. But we need more than
3275 Scheme's normal @code{quasiquote} mechanism to construct build
3278 The @code{(guix gexp)} module implements @dfn{G-expressions}, a form of
3279 S-expressions adapted to build expressions. G-expressions, or
3280 @dfn{gexps}, consist essentially in three syntactic forms: @code{gexp},
3281 @code{ungexp}, and @code{ungexp-splicing} (or simply: @code{#~},
3282 @code{#$}, and @code{#$@@}), which are comparable respectively to
3283 @code{quasiquote}, @code{unquote}, and @code{unquote-splicing}
3284 (@pxref{Expression Syntax, @code{quasiquote},, guile, GNU Guile
3285 Reference Manual}). However, there are major differences:
3289 Gexps are meant to be written to a file and run or manipulated by other
3293 When a high-level object such as a package or derivation is unquoted
3294 inside a gexp, the result is as if its output file name had been
3298 Gexps carry information about the packages or derivations they refer to,
3299 and these dependencies are automatically added as inputs to the build
3300 processes that use them.
3303 @cindex lowering, of high-level objects in gexps
3304 This mechanism is not limited to package and derivation
3305 objects: @dfn{compilers} able to ``lower'' other high-level objects to
3306 derivations or files in the store can be defined,
3307 such that these objects can also be inserted
3308 into gexps. For example, a useful type of high-level object that can be
3309 inserted in a gexp is ``file-like objects'', which make it easy to
3310 add files to the store and refer to them in
3311 derivations and such (see @code{local-file} and @code{plain-file}
3314 To illustrate the idea, here is an example of a gexp:
3321 (symlink (string-append #$coreutils "/bin/ls")
3325 This gexp can be passed to @code{gexp->derivation}; we obtain a
3326 derivation that builds a directory containing exactly one symlink to
3327 @file{/gnu/store/@dots{}-coreutils-8.22/bin/ls}:
3330 (gexp->derivation "the-thing" build-exp)
3333 As one would expect, the @code{"/gnu/store/@dots{}-coreutils-8.22"} string is
3334 substituted to the reference to the @var{coreutils} package in the
3335 actual build code, and @var{coreutils} is automatically made an input to
3336 the derivation. Likewise, @code{#$output} (equivalent to @code{(ungexp
3337 output)}) is replaced by a string containing the derivation's output
3340 @cindex cross compilation
3341 In a cross-compilation context, it is useful to distinguish between
3342 references to the @emph{native} build of a package---that can run on the
3343 host---versus references to cross builds of a package. To that end, the
3344 @code{#+} plays the same role as @code{#$}, but is a reference to a
3345 native package build:
3348 (gexp->derivation "vi"
3351 (system* (string-append #+coreutils "/bin/ln")
3353 (string-append #$emacs "/bin/emacs")
3354 (string-append #$output "/bin/vi")))
3355 #:target "mips64el-linux")
3359 In the example above, the native build of @var{coreutils} is used, so
3360 that @command{ln} can actually run on the host; but then the
3361 cross-compiled build of @var{emacs} is referenced.
3363 The syntactic form to construct gexps is summarized below.
3365 @deffn {Scheme Syntax} #~@var{exp}
3366 @deffnx {Scheme Syntax} (gexp @var{exp})
3367 Return a G-expression containing @var{exp}. @var{exp} may contain one
3368 or more of the following forms:
3372 @itemx (ungexp @var{obj})
3373 Introduce a reference to @var{obj}. @var{obj} may have one of the
3374 supported types, for example a package or a
3375 derivation, in which case the @code{ungexp} form is replaced by its
3376 output file name---e.g., @code{"/gnu/store/@dots{}-coreutils-8.22}.
3378 If @var{obj} is a list, it is traversed and references to supported
3379 objects are substituted similarly.
3381 If @var{obj} is another gexp, its contents are inserted and its
3382 dependencies are added to those of the containing gexp.
3384 If @var{obj} is another kind of object, it is inserted as is.
3386 @item #$@var{obj}:@var{output}
3387 @itemx (ungexp @var{obj} @var{output})
3388 This is like the form above, but referring explicitly to the
3389 @var{output} of @var{obj}---this is useful when @var{obj} produces
3390 multiple outputs (@pxref{Packages with Multiple Outputs}).
3393 @itemx #+@var{obj}:output
3394 @itemx (ungexp-native @var{obj})
3395 @itemx (ungexp-native @var{obj} @var{output})
3396 Same as @code{ungexp}, but produces a reference to the @emph{native}
3397 build of @var{obj} when used in a cross compilation context.
3399 @item #$output[:@var{output}]
3400 @itemx (ungexp output [@var{output}])
3401 Insert a reference to derivation output @var{output}, or to the main
3402 output when @var{output} is omitted.
3404 This only makes sense for gexps passed to @code{gexp->derivation}.
3407 @itemx (ungexp-splicing @var{lst})
3408 Like the above, but splices the contents of @var{lst} inside the
3412 @itemx (ungexp-native-splicing @var{lst})
3413 Like the above, but refers to native builds of the objects listed in
3418 G-expressions created by @code{gexp} or @code{#~} are run-time objects
3419 of the @code{gexp?} type (see below.)
3422 @deffn {Scheme Procedure} gexp? @var{obj}
3423 Return @code{#t} if @var{obj} is a G-expression.
3426 G-expressions are meant to be written to disk, either as code building
3427 some derivation, or as plain files in the store. The monadic procedures
3428 below allow you to do that (@pxref{The Store Monad}, for more
3429 information about monads.)
3431 @deffn {Monadic Procedure} gexp->derivation @var{name} @var{exp} @
3432 [#:system (%current-system)] [#:target #f] [#:graft? #t] @
3433 [#:hash #f] [#:hash-algo #f] @
3434 [#:recursive? #f] [#:env-vars '()] [#:modules '()] @
3435 [#:module-path @var{%load-path}] @
3436 [#:references-graphs #f] [#:allowed-references #f] @
3437 [#:leaked-env-vars #f] @
3438 [#:script-name (string-append @var{name} "-builder")] @
3439 [#:local-build? #f] [#:substitutable? #t] [#:guile-for-build #f]
3440 Return a derivation @var{name} that runs @var{exp} (a gexp) with
3441 @var{guile-for-build} (a derivation) on @var{system}; @var{exp} is
3442 stored in a file called @var{script-name}. When @var{target} is true,
3443 it is used as the cross-compilation target triplet for packages referred
3446 Make @var{modules} available in the evaluation context of @var{exp};
3447 @var{modules} is a list of names of Guile modules searched in
3448 @var{module-path} to be copied in the store, compiled, and made available in
3449 the load path during the execution of @var{exp}---e.g., @code{((guix
3450 build utils) (guix build gnu-build-system))}.
3452 @var{graft?} determines whether packages referred to by @var{exp} should be grafted when
3455 When @var{references-graphs} is true, it must be a list of tuples of one of the
3459 (@var{file-name} @var{package})
3460 (@var{file-name} @var{package} @var{output})
3461 (@var{file-name} @var{derivation})
3462 (@var{file-name} @var{derivation} @var{output})
3463 (@var{file-name} @var{store-item})
3466 The right-hand-side of each element of @var{references-graphs} is automatically made
3467 an input of the build process of @var{exp}. In the build environment, each
3468 @var{file-name} contains the reference graph of the corresponding item, in a simple
3471 @var{allowed-references} must be either @code{#f} or a list of output names and packages.
3472 In the latter case, the list denotes store items that the result is allowed to
3473 refer to. Any reference to another store item will lead to a build error.
3475 The other arguments are as for @code{derivation} (@pxref{Derivations}).
3478 @cindex file-like objects
3479 The @code{local-file}, @code{plain-file}, @code{computed-file},
3480 @code{program-file}, and @code{scheme-file} procedures below return
3481 @dfn{file-like objects}. That is, when unquoted in a G-expression,
3482 these objects lead to a file in the store. Consider this G-expression:
3485 #~(system* (string-append #$glibc "/sbin/nscd") "-f"
3486 #$(local-file "/tmp/my-nscd.conf"))
3489 The effect here is to ``intern'' @file{/tmp/my-nscd.conf} by copying it
3490 to the store. Once expanded, for instance @i{via}
3491 @code{gexp->derivation}, the G-expression refers to that copy under
3492 @file{/gnu/store}; thus, modifying or removing the file in @file{/tmp}
3493 does not have any effect on what the G-expression does.
3494 @code{plain-file} can be used similarly; it differs in that the file
3495 content is directly passed as a string.
3497 @deffn {Scheme Procedure} local-file @var{file} [@var{name}] @
3499 Return an object representing local file @var{file} to add to the store; this
3500 object can be used in a gexp. If @var{file} is a relative file name, it is looked
3501 up relative to the source file where this form appears. @var{file} will be added to
3502 the store under @var{name}--by default the base name of @var{file}.
3504 When @var{recursive?} is true, the contents of @var{file} are added recursively; if @var{file}
3505 designates a flat file and @var{recursive?} is true, its contents are added, and its
3506 permission bits are kept.
3508 This is the declarative counterpart of the @code{interned-file} monadic
3509 procedure (@pxref{The Store Monad, @code{interned-file}}).
3512 @deffn {Scheme Procedure} plain-file @var{name} @var{content}
3513 Return an object representing a text file called @var{name} with the given
3514 @var{content} (a string) to be added to the store.
3516 This is the declarative counterpart of @code{text-file}.
3519 @deffn {Scheme Procedure} computed-file @var{name} @var{gexp} @
3520 [#:modules '()] [#:options '(#:local-build? #t)]
3521 Return an object representing the store item @var{name}, a file or
3522 directory computed by @var{gexp}. @var{modules} specifies the set of
3523 modules visible in the execution context of @var{gexp}. @var{options}
3524 is a list of additional arguments to pass to @code{gexp->derivation}.
3526 This is the declarative counterpart of @code{gexp->derivation}.
3529 @deffn {Monadic Procedure} gexp->script @var{name} @var{exp}
3530 Return an executable script @var{name} that runs @var{exp} using
3531 @var{guile} with @var{modules} in its search path.
3533 The example below builds a script that simply invokes the @command{ls}
3537 (use-modules (guix gexp) (gnu packages base))
3539 (gexp->script "list-files"
3540 #~(execl (string-append #$coreutils "/bin/ls")
3544 When ``running'' it through the store (@pxref{The Store Monad,
3545 @code{run-with-store}}), we obtain a derivation that produces an
3546 executable file @file{/gnu/store/@dots{}-list-files} along these lines:
3549 #!/gnu/store/@dots{}-guile-2.0.11/bin/guile -ds
3551 (execl (string-append "/gnu/store/@dots{}-coreutils-8.22"/bin/ls")
3556 @deffn {Scheme Procedure} program-file @var{name} @var{exp} @
3557 [#:modules '()] [#:guile #f]
3558 Return an object representing the executable store item @var{name} that
3559 runs @var{gexp}. @var{guile} is the Guile package used to execute that
3560 script, and @var{modules} is the list of modules visible to that script.
3562 This is the declarative counterpart of @code{gexp->script}.
3565 @deffn {Monadic Procedure} gexp->file @var{name} @var{exp}
3566 Return a derivation that builds a file @var{name} containing @var{exp}.
3568 The resulting file holds references to all the dependencies of @var{exp}
3569 or a subset thereof.
3572 @deffn {Scheme Procedure} scheme-file @var{name} @var{exp}
3573 Return an object representing the Scheme file @var{name} that contains
3576 This is the declarative counterpart of @code{gexp->file}.
3579 @deffn {Monadic Procedure} text-file* @var{name} @var{text} @dots{}
3580 Return as a monadic value a derivation that builds a text file
3581 containing all of @var{text}. @var{text} may list, in addition to
3582 strings, objects of any type that can be used in a gexp: packages,
3583 derivations, local file objects, etc. The resulting store file holds
3584 references to all these.
3586 This variant should be preferred over @code{text-file} anytime the file
3587 to create will reference items from the store. This is typically the
3588 case when building a configuration file that embeds store file names,
3592 (define (profile.sh)
3593 ;; Return the name of a shell script in the store that
3594 ;; initializes the 'PATH' environment variable.
3595 (text-file* "profile.sh"
3596 "export PATH=" coreutils "/bin:"
3597 grep "/bin:" sed "/bin\n"))
3600 In this example, the resulting @file{/gnu/store/@dots{}-profile.sh} file
3601 will references @var{coreutils}, @var{grep}, and @var{sed}, thereby
3602 preventing them from being garbage-collected during its lifetime.
3605 @deffn {Scheme Procedure} mixed-text-file @var{name} @var{text} @dots{}
3606 Return an object representing store file @var{name} containing
3607 @var{text}. @var{text} is a sequence of strings and file-like objects,
3611 (mixed-text-file "profile"
3612 "export PATH=" coreutils "/bin:" grep "/bin")
3615 This is the declarative counterpart of @code{text-file*}.
3618 Of course, in addition to gexps embedded in ``host'' code, there are
3619 also modules containing build tools. To make it clear that they are
3620 meant to be used in the build stratum, these modules are kept in the
3621 @code{(guix build @dots{})} name space.
3623 @cindex lowering, of high-level objects in gexps
3624 Internally, high-level objects are @dfn{lowered}, using their compiler,
3625 to either derivations or store items. For instance, lowering a package
3626 yields a derivation, and lowering a @code{plain-file} yields a store
3627 item. This is achieved using the @code{lower-object} monadic procedure.
3629 @deffn {Monadic Procedure} lower-object @var{obj} [@var{system}] @
3631 Return as a value in @var{%store-monad} the derivation or store item
3632 corresponding to @var{obj} for @var{system}, cross-compiling for
3633 @var{target} if @var{target} is true. @var{obj} must be an object that
3634 has an associated gexp compiler, such as a @code{<package>}.
3638 @c *********************************************************************
3642 This section describes tools primarily targeted at developers and users
3643 who write new package definitions. They complement the Scheme
3644 programming interface of Guix in a convenient way.
3647 * Invoking guix build:: Building packages from the command line.
3648 * Invoking guix edit:: Editing package definitions.
3649 * Invoking guix download:: Downloading a file and printing its hash.
3650 * Invoking guix hash:: Computing the cryptographic hash of a file.
3651 * Invoking guix import:: Importing package definitions.
3652 * Invoking guix refresh:: Updating package definitions.
3653 * Invoking guix lint:: Finding errors in package definitions.
3654 * Invoking guix size:: Profiling disk usage.
3655 * Invoking guix graph:: Visualizing the graph of packages.
3656 * Invoking guix environment:: Setting up development environments.
3657 * Invoking guix publish:: Sharing substitutes.
3658 * Invoking guix challenge:: Challenging substitute servers.
3659 * Invoking guix container:: Process isolation.
3662 @node Invoking guix build
3663 @section Invoking @command{guix build}
3665 The @command{guix build} command builds packages or derivations and
3666 their dependencies, and prints the resulting store paths. Note that it
3667 does not modify the user's profile---this is the job of the
3668 @command{guix package} command (@pxref{Invoking guix package}). Thus,
3669 it is mainly useful for distribution developers.
3671 The general syntax is:
3674 guix build @var{options} @var{package-or-derivation}@dots{}
3677 @var{package-or-derivation} may be either the name of a package found in
3678 the software distribution such as @code{coreutils} or
3679 @code{coreutils-8.20}, or a derivation such as
3680 @file{/gnu/store/@dots{}-coreutils-8.19.drv}. In the former case, a
3681 package with the corresponding name (and optionally version) is searched
3682 for among the GNU distribution modules (@pxref{Package Modules}).
3684 Alternatively, the @code{--expression} option may be used to specify a
3685 Scheme expression that evaluates to a package; this is useful when
3686 disambiguation among several same-named packages or package variants is
3689 The @var{options} may be zero or more of the following:
3693 @item --file=@var{file}
3694 @itemx -f @var{file}
3696 Build the package or derivation that the code within @var{file}
3699 As an example, @var{file} might contain a package definition like this
3700 (@pxref{Defining Packages}):
3703 @verbatiminclude package-hello.scm
3706 @item --expression=@var{expr}
3707 @itemx -e @var{expr}
3708 Build the package or derivation @var{expr} evaluates to.
3710 For example, @var{expr} may be @code{(@@ (gnu packages guile)
3711 guile-1.8)}, which unambiguously designates this specific variant of
3712 version 1.8 of Guile.
3714 Alternately, @var{expr} may be a G-expression, in which case it is used
3715 as a build program passed to @code{gexp->derivation}
3716 (@pxref{G-Expressions}).
3718 Lastly, @var{expr} may refer to a zero-argument monadic procedure
3719 (@pxref{The Store Monad}). The procedure must return a derivation as a
3720 monadic value, which is then passed through @code{run-with-store}.
3724 Build the packages' source derivations, rather than the packages
3727 For instance, @code{guix build -S gcc} returns something like
3728 @file{/gnu/store/@dots{}-gcc-4.7.2.tar.bz2}, which is GCC's source tarball.
3730 The returned source tarball is the result of applying any patches and
3731 code snippets specified in the package's @code{origin} (@pxref{Defining
3735 Fetch and return the source of @var{package-or-derivation} and all their
3736 dependencies, recursively. This is a handy way to obtain a local copy
3737 of all the source code needed to build @var{packages}, allowing you to
3738 eventually build them even without network access. It is an extension
3739 of the @code{--source} option and can accept one of the following
3740 optional argument values:
3744 This value causes the @code{--sources} option to behave in the same way
3745 as the @code{--source} option.
3748 Build all packages' source derivations, including any source that might
3749 be listed as @code{inputs}. This is the default value.
3752 $ guix build --sources tzdata
3753 The following derivations will be built:
3754 /gnu/store/@dots{}-tzdata2015b.tar.gz.drv
3755 /gnu/store/@dots{}-tzcode2015b.tar.gz.drv
3759 Build all packages' source derivations, as well as all source
3760 derivations for packages' transitive inputs. This can be used e.g. to
3761 prefetch package source for later offline building.
3764 $ guix build --sources=transitive tzdata
3765 The following derivations will be built:
3766 /gnu/store/@dots{}-tzcode2015b.tar.gz.drv
3767 /gnu/store/@dots{}-findutils-4.4.2.tar.xz.drv
3768 /gnu/store/@dots{}-grep-2.21.tar.xz.drv
3769 /gnu/store/@dots{}-coreutils-8.23.tar.xz.drv
3770 /gnu/store/@dots{}-make-4.1.tar.xz.drv
3771 /gnu/store/@dots{}-bash-4.3.tar.xz.drv
3777 @item --system=@var{system}
3778 @itemx -s @var{system}
3779 Attempt to build for @var{system}---e.g., @code{i686-linux}---instead of
3780 the host's system type.
3782 An example use of this is on Linux-based systems, which can emulate
3783 different personalities. For instance, passing
3784 @code{--system=i686-linux} on an @code{x86_64-linux} system allows users
3785 to build packages in a complete 32-bit environment.
3787 @item --target=@var{triplet}
3788 @cindex cross-compilation
3789 Cross-build for @var{triplet}, which must be a valid GNU triplet, such
3790 as @code{"mips64el-linux-gnu"} (@pxref{Configuration Names, GNU
3791 configuration triplets,, configure, GNU Configure and Build System}).
3793 @item --with-source=@var{source}
3794 Use @var{source} as the source of the corresponding package.
3795 @var{source} must be a file name or a URL, as for @command{guix
3796 download} (@pxref{Invoking guix download}).
3798 The ``corresponding package'' is taken to be one specified on the
3799 command line whose name matches the base of @var{source}---e.g., if
3800 @var{source} is @code{/src/guile-2.0.10.tar.gz}, the corresponding
3801 package is @code{guile}. Likewise, the version string is inferred from
3802 @var{source}; in the previous example, it's @code{2.0.10}.
3804 This option allows users to try out versions of packages other than the
3805 one provided by the distribution. The example below downloads
3806 @file{ed-1.7.tar.gz} from a GNU mirror and uses that as the source for
3807 the @code{ed} package:
3810 guix build ed --with-source=mirror://gnu/ed/ed-1.7.tar.gz
3813 As a developer, @code{--with-source} makes it easy to test release
3817 guix build guile --with-source=../guile-2.0.9.219-e1bb7.tar.xz
3820 @dots{} or to build from a checkout in a pristine environment:
3823 $ git clone git://git.sv.gnu.org/guix.git
3824 $ guix build guix --with-source=./guix
3827 @anchor{build-check}
3829 @cindex determinism, checking
3830 @cindex reproducibility, checking
3831 Rebuild @var{package-or-derivation}, which are already available in the
3832 store, and raise an error if the build results are not bit-for-bit
3835 This mechanism allows you to check whether previously-installed
3836 substitutes are genuine (@pxref{Substitutes}), or whether a package's
3837 build result is deterministic. @xref{Invoking guix challenge}, for more
3838 background information and tools.
3841 Do not ``graft'' packages. In practice, this means that package updates
3842 available as grafts are not applied. @xref{Security Updates}, for more
3843 information on grafts.
3847 Return the derivation paths, not the output paths, of the given
3850 @item --root=@var{file}
3851 @itemx -r @var{file}
3852 Make @var{file} a symlink to the result, and register it as a garbage
3856 Return the build log file names or URLs for the given
3857 @var{package-or-derivation}s, or raise an error if build logs are
3860 This works regardless of how packages or derivations are specified. For
3861 instance, the following invocations are equivalent:
3864 guix build --log-file `guix build -d guile`
3865 guix build --log-file `guix build guile`
3866 guix build --log-file guile
3867 guix build --log-file -e '(@@ (gnu packages guile) guile-2.0)'
3870 If a log is unavailable locally, and unless @code{--no-substitutes} is
3871 passed, the command looks for a corresponding log on one of the
3872 substitute servers (as specified with @code{--substitute-urls}.)
3874 So for instance, let's say you want to see the build log of GDB on MIPS
3875 but you're actually on an @code{x86_64} machine:
3878 $ guix build --log-file gdb -s mips64el-linux
3879 http://hydra.gnu.org/log/@dots{}-gdb-7.10
3882 You can freely access a huge library of build logs!
3885 @cindex common build options
3886 In addition, a number of options that control the build process are
3887 common to @command{guix build} and other commands that can spawn builds,
3888 such as @command{guix package} or @command{guix archive}. These are the
3893 @item --load-path=@var{directory}
3894 @itemx -L @var{directory}
3895 Add @var{directory} to the front of the package module search path
3896 (@pxref{Package Modules}).
3898 This allows users to define their own packages and make them visible to
3899 the command-line tools.
3903 Keep the build tree of failed builds. Thus, if a build fail, its build
3904 tree is kept under @file{/tmp}, in a directory whose name is shown at
3905 the end of the build log. This is useful when debugging build issues.
3909 Do not build the derivations.
3912 When substituting a pre-built binary fails, fall back to building
3915 @item --substitute-urls=@var{urls}
3916 @anchor{client-substitute-urls}
3917 Consider @var{urls} the whitespace-separated list of substitute source
3918 URLs, overriding the default list of URLs of @command{guix-daemon}
3919 (@pxref{daemon-substitute-urls,, @command{guix-daemon} URLs}).
3921 This means that substitutes may be downloaded from @var{urls}, provided
3922 they are signed by a key authorized by the system administrator
3923 (@pxref{Substitutes}).
3925 @item --no-substitutes
3926 Do not use substitutes for build products. That is, always build things
3927 locally instead of allowing downloads of pre-built binaries
3928 (@pxref{Substitutes}).
3930 @item --rounds=@var{n}
3931 Build each derivation @var{n} times in a row, and raise an error if
3932 consecutive build results are not bit-for-bit identical.
3934 This is a useful way to detect non-deterministic builds processes.
3935 Non-deterministic build processes are a problem because they make it
3936 practically impossible for users to @emph{verify} whether third-party
3937 binaries are genuine. @xref{Invoking guix challenge}, for more.
3939 Note that, currently, the differing build results are not kept around,
3940 so you will have to manually investigate in case of an error---e.g., by
3941 stashing one of the build results with @code{guix archive --export},
3942 then rebuilding, and finally comparing the two results.
3944 @item --no-build-hook
3945 Do not attempt to offload builds @i{via} the daemon's ``build hook''
3946 (@pxref{Daemon Offload Setup}). That is, always build things locally
3947 instead of offloading builds to remote machines.
3949 @item --max-silent-time=@var{seconds}
3950 When the build or substitution process remains silent for more than
3951 @var{seconds}, terminate it and report a build failure.
3953 @item --timeout=@var{seconds}
3954 Likewise, when the build or substitution process lasts for more than
3955 @var{seconds}, terminate it and report a build failure.
3957 By default there is no timeout. This behavior can be restored with
3960 @item --verbosity=@var{level}
3961 Use the given verbosity level. @var{level} must be an integer between 0
3962 and 5; higher means more verbose output. Setting a level of 4 or more
3963 may be helpful when debugging setup issues with the build daemon.
3965 @item --cores=@var{n}
3967 Allow the use of up to @var{n} CPU cores for the build. The special
3968 value @code{0} means to use as many CPU cores as available.
3970 @item --max-jobs=@var{n}
3972 Allow at most @var{n} build jobs in parallel. @xref{Invoking
3973 guix-daemon, @code{--max-jobs}}, for details about this option and the
3974 equivalent @command{guix-daemon} option.
3978 Behind the scenes, @command{guix build} is essentially an interface to
3979 the @code{package-derivation} procedure of the @code{(guix packages)}
3980 module, and to the @code{build-derivations} procedure of the @code{(guix
3981 derivations)} module.
3983 In addition to options explicitly passed on the command line,
3984 @command{guix build} and other @command{guix} commands that support
3985 building honor the @code{GUIX_BUILD_OPTIONS} environment variable.
3987 @defvr {Environment Variable} GUIX_BUILD_OPTIONS
3988 Users can define this variable to a list of command line options that
3989 will automatically be used by @command{guix build} and other
3990 @command{guix} commands that can perform builds, as in the example
3994 $ export GUIX_BUILD_OPTIONS="--no-substitutes -c 2 -L /foo/bar"
3997 These options are parsed independently, and the result is appended to
3998 the parsed command-line options.
4002 @node Invoking guix edit
4003 @section Invoking @command{guix edit}
4005 @cindex package definition, editing
4006 So many packages, so many source files! The @command{guix edit} command
4007 facilitates the life of packagers by pointing their editor at the source
4008 file containing the definition of the specified packages. For instance:
4011 guix edit gcc-4.8 vim
4015 launches the program specified in the @code{VISUAL} or in the
4016 @code{EDITOR} environment variable to edit the recipe of GCC@tie{}4.8.4
4019 If you are using Emacs, note that the Emacs user interface provides
4020 similar functionality in the ``package info'' and ``package list''
4021 buffers created by @kbd{M-x guix-search-by-name} and similar commands
4022 (@pxref{Emacs Commands}).
4025 @node Invoking guix download
4026 @section Invoking @command{guix download}
4028 When writing a package definition, developers typically need to download
4029 the package's source tarball, compute its SHA256 hash, and write that
4030 hash in the package definition (@pxref{Defining Packages}). The
4031 @command{guix download} tool helps with this task: it downloads a file
4032 from the given URI, adds it to the store, and prints both its file name
4033 in the store and its SHA256 hash.
4035 The fact that the downloaded file is added to the store saves bandwidth:
4036 when the developer eventually tries to build the newly defined package
4037 with @command{guix build}, the source tarball will not have to be
4038 downloaded again because it is already in the store. It is also a
4039 convenient way to temporarily stash files, which may be deleted
4040 eventually (@pxref{Invoking guix gc}).
4042 The @command{guix download} command supports the same URIs as used in
4043 package definitions. In particular, it supports @code{mirror://} URIs.
4044 @code{https} URIs (HTTP over TLS) are supported @emph{provided} the
4045 Guile bindings for GnuTLS are available in the user's environment; when
4046 they are not available, an error is raised. @xref{Guile Preparations,
4047 how to install the GnuTLS bindings for Guile,, gnutls-guile,
4048 GnuTLS-Guile}, for more information.
4050 The following option is available:
4053 @item --format=@var{fmt}
4055 Write the hash in the format specified by @var{fmt}. For more
4056 information on the valid values for @var{fmt}, @pxref{Invoking guix hash}.
4059 @node Invoking guix hash
4060 @section Invoking @command{guix hash}
4062 The @command{guix hash} command computes the SHA256 hash of a file.
4063 It is primarily a convenience tool for anyone contributing to the
4064 distribution: it computes the cryptographic hash of a file, which can be
4065 used in the definition of a package (@pxref{Defining Packages}).
4067 The general syntax is:
4070 guix hash @var{option} @var{file}
4073 @command{guix hash} has the following option:
4077 @item --format=@var{fmt}
4079 Write the hash in the format specified by @var{fmt}.
4081 Supported formats: @code{nix-base32}, @code{base32}, @code{base16}
4082 (@code{hex} and @code{hexadecimal} can be used as well).
4084 If the @option{--format} option is not specified, @command{guix hash}
4085 will output the hash in @code{nix-base32}. This representation is used
4086 in the definitions of packages.
4090 Compute the hash on @var{file} recursively.
4092 In this case, the hash is computed on an archive containing @var{file},
4093 including its children if it is a directory. Some of @var{file}'s
4094 meta-data is part of the archive; for instance, when @var{file} is a
4095 regular file, the hash is different depending on whether @var{file} is
4096 executable or not. Meta-data such as time stamps has no impact on the
4097 hash (@pxref{Invoking guix archive}).
4098 @c FIXME: Replace xref above with xref to an ``Archive'' section when
4103 @node Invoking guix import
4104 @section Invoking @command{guix import}
4106 @cindex importing packages
4107 @cindex package import
4108 @cindex package conversion
4109 The @command{guix import} command is useful for people willing to add a
4110 package to the distribution but who'd rather do as little work as
4111 possible to get there---a legitimate demand. The command knows of a few
4112 repositories from which it can ``import'' package meta-data. The result
4113 is a package definition, or a template thereof, in the format we know
4114 (@pxref{Defining Packages}).
4116 The general syntax is:
4119 guix import @var{importer} @var{options}@dots{}
4122 @var{importer} specifies the source from which to import package
4123 meta-data, and @var{options} specifies a package identifier and other
4124 options specific to @var{importer}. Currently, the available
4129 Import meta-data for the given GNU package. This provides a template
4130 for the latest version of that GNU package, including the hash of its
4131 source tarball, and its canonical synopsis and description.
4133 Additional information such as the package's dependencies and its
4134 license needs to be figured out manually.
4136 For example, the following command returns a package definition for
4140 guix import gnu hello
4143 Specific command-line options are:
4146 @item --key-download=@var{policy}
4147 As for @code{guix refresh}, specify the policy to handle missing OpenPGP
4148 keys when verifying the package's signature. @xref{Invoking guix
4149 refresh, @code{--key-download}}.
4154 Import meta-data from the @uref{https://pypi.python.org/, Python Package
4155 Index}@footnote{This functionality requires Guile-JSON to be installed.
4156 @xref{Requirements}.}. Information is taken from the JSON-formatted
4157 description available at @code{pypi.python.org} and usually includes all
4158 the relevant information, including package dependencies.
4160 The command below imports meta-data for the @code{itsdangerous} Python
4164 guix import pypi itsdangerous
4169 Import meta-data from @uref{https://rubygems.org/,
4170 RubyGems}@footnote{This functionality requires Guile-JSON to be
4171 installed. @xref{Requirements}.}. Information is taken from the
4172 JSON-formatted description available at @code{rubygems.org} and includes
4173 most relevant information, including runtime dependencies. There are
4174 some caveats, however. The meta-data doesn't distinguish between
4175 synopses and descriptions, so the same string is used for both fields.
4176 Additionally, the details of non-Ruby dependencies required to build
4177 native extensions is unavailable and left as an exercise to the
4180 The command below imports meta-data for the @code{rails} Ruby package:
4183 guix import gem rails
4188 Import meta-data from @uref{https://www.metacpan.org/, MetaCPAN}.
4189 Information is taken from the JSON-formatted meta-data provided through
4190 @uref{https://api.metacpan.org/, MetaCPAN's API} and includes most
4191 relevant information, such as module dependencies. License information
4192 should be checked closely. If Perl is available in the store, then the
4193 @code{corelist} utility will be used to filter core modules out of the
4194 list of dependencies.
4196 The command command below imports meta-data for the @code{Acme::Boolean}
4200 guix import cpan Acme::Boolean
4205 Import meta-data from @uref{http://cran.r-project.org/, CRAN}, the
4206 central repository for the @uref{http://r-project.org, GNU@tie{}R
4207 statistical and graphical environment}.
4209 Information is extracted from the package's DESCRIPTION file.
4211 The command command below imports meta-data for the @code{Cairo}
4215 guix import cran Cairo
4219 Import meta-data from a local copy of the source of the
4220 @uref{http://nixos.org/nixpkgs/, Nixpkgs distribution}@footnote{This
4221 relies on the @command{nix-instantiate} command of
4222 @uref{http://nixos.org/nix/, Nix}.}. Package definitions in Nixpkgs are
4223 typically written in a mixture of Nix-language and Bash code. This
4224 command only imports the high-level package structure that is written in
4225 the Nix language. It normally includes all the basic fields of a
4228 When importing a GNU package, the synopsis and descriptions are replaced
4229 by their canonical upstream variant.
4231 Usually, you will first need to do:
4234 export NIX_REMOTE=daemon
4238 so that @command{nix-instantiate} does not try to open the Nix database.
4240 As an example, the command below imports the package definition of
4241 LibreOffice (more precisely, it imports the definition of the package
4242 bound to the @code{libreoffice} top-level attribute):
4245 guix import nix ~/path/to/nixpkgs libreoffice
4250 Import meta-data from Haskell community's central package archive
4251 @uref{https://hackage.haskell.org/, Hackage}. Information is taken from
4252 Cabal files and includes all the relevant information, including package
4255 Specific command-line options are:
4260 Read a Cabal file from the standard input.
4261 @item --no-test-dependencies
4263 Do not include dependencies required by the test suites only.
4264 @item --cabal-environment=@var{alist}
4265 @itemx -e @var{alist}
4266 @var{alist} is a Scheme alist defining the environment in which the
4267 Cabal conditionals are evaluated. The accepted keys are: @code{os},
4268 @code{arch}, @code{impl} and a string representing the name of a flag.
4269 The value associated with a flag has to be either the symbol
4270 @code{true} or @code{false}. The value associated with other keys
4271 has to conform to the Cabal file format definition. The default value
4272 associated with the keys @code{os}, @code{arch} and @code{impl} is
4273 @samp{linux}, @samp{x86_64} and @samp{ghc} respectively.
4276 The command below imports meta-data for the latest version of the
4277 @code{HTTP} Haskell package without including test dependencies and
4278 specifying the value of the flag @samp{network-uri} as @code{false}:
4281 guix import hackage -t -e "'((\"network-uri\" . false))" HTTP
4284 A specific package version may optionally be specified by following the
4285 package name by a hyphen and a version number as in the following example:
4288 guix import hackage mtl-2.1.3.1
4293 Import meta-data from an Emacs Lisp Package Archive (ELPA) package
4294 repository (@pxref{Packages,,, emacs, The GNU Emacs Manual}).
4296 Specific command-line options are:
4299 @item --archive=@var{repo}
4300 @itemx -a @var{repo}
4301 @var{repo} identifies the archive repository from which to retrieve the
4302 information. Currently the supported repositories and their identifiers
4306 @uref{http://elpa.gnu.org/packages, GNU}, selected by the @code{gnu}
4307 identifier. This is the default.
4310 @uref{http://stable.melpa.org/packages, MELPA-Stable}, selected by the
4311 @code{melpa-stable} identifier.
4314 @uref{http://melpa.org/packages, MELPA}, selected by the @code{melpa}
4320 The structure of the @command{guix import} code is modular. It would be
4321 useful to have more importers for other package formats, and your help
4322 is welcome here (@pxref{Contributing}).
4324 @node Invoking guix refresh
4325 @section Invoking @command{guix refresh}
4327 The primary audience of the @command{guix refresh} command is developers
4328 of the GNU software distribution. By default, it reports any packages
4329 provided by the distribution that are outdated compared to the latest
4330 upstream version, like this:
4334 gnu/packages/gettext.scm:29:13: gettext would be upgraded from 0.18.1.1 to 0.18.2.1
4335 gnu/packages/glib.scm:77:12: glib would be upgraded from 2.34.3 to 2.37.0
4338 It does so by browsing each package's FTP directory and determining the
4339 highest version number of the source tarballs therein. The command
4340 knows how to update specific types of packages: GNU packages, ELPA
4341 packages, etc.---see the documentation for @option{--type} below. The
4342 are many packages, though, for which it lacks a method to determine
4343 whether a new upstream release is available. However, the mechanism is
4344 extensible, so feel free to get in touch with us to add a new method!
4346 When passed @code{--update}, it modifies distribution source files to
4347 update the version numbers and source tarball hashes of those packages'
4348 recipes (@pxref{Defining Packages}). This is achieved by downloading
4349 each package's latest source tarball and its associated OpenPGP
4350 signature, authenticating the downloaded tarball against its signature
4351 using @command{gpg}, and finally computing its hash. When the public
4352 key used to sign the tarball is missing from the user's keyring, an
4353 attempt is made to automatically retrieve it from a public key server;
4354 when it's successful, the key is added to the user's keyring; otherwise,
4355 @command{guix refresh} reports an error.
4357 The following options are supported:
4361 @item --expression=@var{expr}
4362 @itemx -e @var{expr}
4363 Consider the package @var{expr} evaluates to.
4365 This is useful to precisely refer to a package, as in this example:
4368 guix refresh -l -e '(@@@@ (gnu packages commencement) glibc-final)'
4371 This command lists the dependents of the ``final'' libc (essentially all
4376 Update distribution source files (package recipes) in place. This is
4377 usually run from a checkout of the Guix source tree (@pxref{Running
4378 Guix Before It Is Installed}):
4381 $ ./pre-inst-env guix refresh -s non-core
4384 @xref{Defining Packages}, for more information on package definitions.
4386 @item --select=[@var{subset}]
4387 @itemx -s @var{subset}
4388 Select all the packages in @var{subset}, one of @code{core} or
4391 The @code{core} subset refers to all the packages at the core of the
4392 distribution---i.e., packages that are used to build ``everything
4393 else''. This includes GCC, libc, Binutils, Bash, etc. Usually,
4394 changing one of these packages in the distribution entails a rebuild of
4395 all the others. Thus, such updates are an inconvenience to users in
4396 terms of build time or bandwidth used to achieve the upgrade.
4398 The @code{non-core} subset refers to the remaining packages. It is
4399 typically useful in cases where an update of the core packages would be
4402 @item --type=@var{updater}
4403 @itemx -t @var{updater}
4404 Select only packages handled by @var{updater} (may be a comma-separated
4405 list of updaters). Currently, @var{updater} may be one of:
4409 the updater for GNU packages;
4411 the updater for GNOME packages;
4413 the updater for @uref{http://elpa.gnu.org/, ELPA} packages;
4415 the updater for @uref{http://cran.r-project.org/, CRAN} packages;
4417 the updater for @uref{https://pypi.python.org, PyPI} packages.
4420 For instance, the following commands only checks for updates of Emacs
4421 packages hosted at @code{elpa.gnu.org} and updates of CRAN packages:
4424 $ guix refresh --type=elpa,cran
4425 gnu/packages/statistics.scm:819:13: r-testthat would be upgraded from 0.10.0 to 0.11.0
4426 gnu/packages/emacs.scm:856:13: emacs-auctex would be upgraded from 11.88.6 to 11.88.9
4431 In addition, @command{guix refresh} can be passed one or more package
4432 names, as in this example:
4435 $ ./pre-inst-env guix refresh -u emacs idutils gcc-4.8.4
4439 The command above specifically updates the @code{emacs} and
4440 @code{idutils} packages. The @code{--select} option would have no
4441 effect in this case.
4443 When considering whether to upgrade a package, it is sometimes
4444 convenient to know which packages would be affected by the upgrade and
4445 should be checked for compatibility. For this the following option may
4446 be used when passing @command{guix refresh} one or more package names:
4450 @item --list-updaters
4452 List available updaters and exit (see @option{--type} above.)
4454 @item --list-dependent
4456 List top-level dependent packages that would need to be rebuilt as a
4457 result of upgrading one or more packages.
4461 Be aware that the @code{--list-dependent} option only
4462 @emph{approximates} the rebuilds that would be required as a result of
4463 an upgrade. More rebuilds might be required under some circumstances.
4466 $ guix refresh --list-dependent flex
4467 Building the following 120 packages would ensure 213 dependent packages are rebuilt:
4468 hop-2.4.0 geiser-0.4 notmuch-0.18 mu-0.9.9.5 cflow-1.4 idutils-4.6 @dots{}
4471 The command above lists a set of packages that could be built to check
4472 for compatibility with an upgraded @code{flex} package.
4474 The following options can be used to customize GnuPG operation:
4478 @item --gpg=@var{command}
4479 Use @var{command} as the GnuPG 2.x command. @var{command} is searched
4480 for in @code{$PATH}.
4482 @item --key-download=@var{policy}
4483 Handle missing OpenPGP keys according to @var{policy}, which may be one
4488 Always download missing OpenPGP keys from the key server, and add them
4489 to the user's GnuPG keyring.
4492 Never try to download missing OpenPGP keys. Instead just bail out.
4495 When a package signed with an unknown OpenPGP key is encountered, ask
4496 the user whether to download it or not. This is the default behavior.
4499 @item --key-server=@var{host}
4500 Use @var{host} as the OpenPGP key server when importing a public key.
4504 @node Invoking guix lint
4505 @section Invoking @command{guix lint}
4506 The @command{guix lint} is meant to help package developers avoid common
4507 errors and use a consistent style. It runs a number of checks on a
4508 given set of packages in order to find common mistakes in their
4509 definitions. Available @dfn{checkers} include (see
4510 @code{--list-checkers} for a complete list):
4515 Validate certain typographical and stylistic rules about package
4516 descriptions and synopses.
4518 @item inputs-should-be-native
4519 Identify inputs that should most likely be native inputs.
4523 @itemx source-file-name
4524 Probe @code{home-page} and @code{source} URLs and report those that are
4525 invalid. Check that the source file name is meaningful, e.g. is not
4526 just a version number or ``git-checkout'', and should not have a
4527 @code{file-name} declared (@pxref{origin Reference}).
4530 Report known vulnerabilities found in the Common Vulnerabilities and
4531 Exposures (CVE) database
4532 @uref{https://nvd.nist.gov/download.cfm#CVE_FEED, published by the US
4536 Warn about obvious source code formatting issues: trailing white space,
4537 use of tabulations, etc.
4540 The general syntax is:
4543 guix lint @var{options} @var{package}@dots{}
4546 If no package is given on the command line, then all packages are checked.
4547 The @var{options} may be zero or more of the following:
4553 Only enable the checkers specified in a comma-separated list using the
4554 names returned by @code{--list-checkers}.
4556 @item --list-checkers
4558 List and describe all the available checkers that will be run on packages
4563 @node Invoking guix size
4564 @section Invoking @command{guix size}
4566 The @command{guix size} command helps package developers profile the
4567 disk usage of packages. It is easy to overlook the impact of an
4568 additional dependency added to a package, or the impact of using a
4569 single output for a package that could easily be split (@pxref{Packages
4570 with Multiple Outputs}). These are the typical issues that
4571 @command{guix size} can highlight.
4573 The command can be passed a package specification such as @code{gcc-4.8}
4574 or @code{guile:debug}, or a file name in the store. Consider this
4578 $ guix size coreutils
4579 store item total self
4580 /gnu/store/@dots{}-coreutils-8.23 70.0 13.9 19.8%
4581 /gnu/store/@dots{}-gmp-6.0.0a 55.3 2.5 3.6%
4582 /gnu/store/@dots{}-acl-2.2.52 53.7 0.5 0.7%
4583 /gnu/store/@dots{}-attr-2.4.46 53.2 0.3 0.5%
4584 /gnu/store/@dots{}-gcc-4.8.4-lib 52.9 15.7 22.4%
4585 /gnu/store/@dots{}-glibc-2.21 37.2 37.2 53.1%
4589 The store items listed here constitute the @dfn{transitive closure} of
4590 Coreutils---i.e., Coreutils and all its dependencies, recursively---as
4591 would be returned by:
4594 $ guix gc -R /gnu/store/@dots{}-coreutils-8.23
4597 Here the output shows 3 columns next to store items. The first column,
4598 labeled ``total'', shows the size in mebibytes (MiB) of the closure of
4599 the store item---that is, its own size plus the size of all its
4600 dependencies. The next column, labeled ``self'', shows the size of the
4601 item itself. The last column shows the ratio of the item's size to the
4602 space occupied by all the items listed here.
4604 In this example, we see that the closure of Coreutils weighs in at
4605 70@tie{}MiB, half of which is taken by libc. (That libc represents a
4606 large fraction of the closure is not a problem @i{per se} because it is
4607 always available on the system anyway.)
4609 When the package passed to @command{guix size} is available in the
4610 store, @command{guix size} queries the daemon to determine its
4611 dependencies, and measures its size in the store, similar to @command{du
4612 -ms --apparent-size} (@pxref{du invocation,,, coreutils, GNU
4615 When the given package is @emph{not} in the store, @command{guix size}
4616 reports information based on information about the available substitutes
4617 (@pxref{Substitutes}). This allows it to profile disk usage of store
4618 items that are not even on disk, only available remotely.
4620 The available options are:
4624 @item --substitute-urls=@var{urls}
4625 Use substitute information from @var{urls}.
4626 @xref{client-substitute-urls, the same option for @code{guix build}}.
4628 @item --map-file=@var{file}
4629 Write to @var{file} a graphical map of disk usage as a PNG file.
4631 For the example above, the map looks like this:
4633 @image{images/coreutils-size-map,5in,, map of Coreutils disk usage
4634 produced by @command{guix size}}
4636 This option requires that
4637 @uref{http://wingolog.org/software/guile-charting/, Guile-Charting} be
4638 installed and visible in Guile's module search path. When that is not
4639 the case, @command{guix size} fails as it tries to load it.
4641 @item --system=@var{system}
4642 @itemx -s @var{system}
4643 Consider packages for @var{system}---e.g., @code{x86_64-linux}.
4647 @node Invoking guix graph
4648 @section Invoking @command{guix graph}
4651 Packages and their dependencies form a @dfn{graph}, specifically a
4652 directed acyclic graph (DAG). It can quickly become difficult to have a
4653 mental model of the package DAG, so the @command{guix graph} command is
4654 here to provide a visual representation of the DAG. @command{guix
4655 graph} emits a DAG representation in the input format of
4656 @uref{http://www.graphviz.org/, Graphviz}, so its output can be passed
4657 directly to Graphviz's @command{dot} command, for instance. The general
4661 guix graph @var{options} @var{package}@dots{}
4664 For example, the following command generates a PDF file representing the
4665 package DAG for the GNU@tie{}Core Utilities, showing its build-time
4669 guix graph coreutils | dot -Tpdf > dag.pdf
4672 The output looks like this:
4674 @image{images/coreutils-graph,2in,,Dependency graph of the GNU Coreutils}
4676 Nice little graph, no?
4678 But there's more than one graph! The one above is concise: it's the
4679 graph of package objects, omitting implicit inputs such as GCC, libc,
4680 grep, etc. It's often useful to have such a concise graph, but
4681 sometimes you want to see more details. @command{guix graph} supports
4682 several types of graphs, allowing you to choose the level of details:
4686 This is the default type, the one we used above. It shows the DAG of
4687 package objects, excluding implicit dependencies. It is concise, but
4688 filters out many details.
4691 This is the package DAG, @emph{including} implicit inputs.
4693 For instance, the following command:
4696 guix graph --type=bag-emerged coreutils | dot -Tpdf > dag.pdf
4699 ... yields this bigger graph:
4701 @image{images/coreutils-bag-graph,,5in,Detailed dependency graph of the GNU Coreutils}
4703 At the bottom of the graph, we see all the implicit inputs of
4704 @var{gnu-build-system} (@pxref{Build Systems, @code{gnu-build-system}}).
4706 Now, note that the dependencies of those implicit inputs---that is, the
4707 @dfn{bootstrap dependencies} (@pxref{Bootstrapping})---are not shown
4708 here, for conciseness.
4711 Similar to @code{bag-emerged}, but this time including all the bootstrap
4714 @item bag-with-origins
4715 Similar to @code{bag}, but also showing origins and their dependencies.
4718 This is the most detailed representation: It shows the DAG of
4719 derivations (@pxref{Derivations}) and plain store items. Compared to
4720 the above representation, many additional nodes are visible, including
4721 builds scripts, patches, Guile modules, etc.
4725 All the above types correspond to @emph{build-time dependencies}. The
4726 following graph type represents the @emph{run-time dependencies}:
4730 This is the graph of @dfn{references} of a package output, as returned
4731 by @command{guix gc --references} (@pxref{Invoking guix gc}).
4733 If the given package output is not available in the store, @command{guix
4734 graph} attempts to obtain dependency information from substitutes.
4737 The available options are the following:
4740 @item --type=@var{type}
4741 @itemx -t @var{type}
4742 Produce a graph output of @var{type}, where @var{type} must be one of
4743 the values listed above.
4746 List the supported graph types.
4748 @item --expression=@var{expr}
4749 @itemx -e @var{expr}
4750 Consider the package @var{expr} evaluates to.
4752 This is useful to precisely refer to a package, as in this example:
4755 guix graph -e '(@@@@ (gnu packages commencement) gnu-make-final)'
4760 @node Invoking guix environment
4761 @section Invoking @command{guix environment}
4763 @cindex reproducible build environments
4764 @cindex development environments
4765 The purpose of @command{guix environment} is to assist hackers in
4766 creating reproducible development environments without polluting their
4767 package profile. The @command{guix environment} tool takes one or more
4768 packages, builds all of the necessary inputs, and creates a shell
4769 environment to use them.
4771 The general syntax is:
4774 guix environment @var{options} @var{package}@dots{}
4777 The following example spawns a new shell set up for the development of
4781 guix environment guile
4784 If the specified packages are not built yet, @command{guix environment}
4785 automatically builds them. The new shell's environment is an augmented
4786 version of the environment that @command{guix environment} was run in.
4787 It contains the necessary search paths for building the given package
4788 added to the existing environment variables. To create a ``pure''
4789 environment in which the original environment variables have been unset,
4790 use the @code{--pure} option@footnote{Users sometimes wrongfully augment
4791 environment variables such as @code{PATH} in their @file{~/.bashrc}
4792 file. As a consequence, when @code{guix environment} launches it, Bash
4793 may read @file{~/.bashrc}, thereby introducing ``impurities'' in these
4794 environment variables. It is an error to define such environment
4795 variables in @file{.bashrc}; instead, they should be defined in
4796 @file{.bash_profile}, which is sourced only by log-in shells.
4797 @xref{Bash Startup Files,,, bash, The GNU Bash Reference Manual}, for
4798 details on Bash start-up files.}.
4800 @vindex GUIX_ENVIRONMENT
4801 @command{guix environment} defines the @code{GUIX_ENVIRONMENT}
4802 variable in the shell it spaws. This allows users to, say, define a
4803 specific prompt for development environments in their @file{.bashrc}
4804 (@pxref{Bash Startup Files,,, bash, The GNU Bash Reference Manual}):
4807 if [ -n "$GUIX_ENVIRONMENT" ]
4809 export PS1="\u@@\h \w [dev]\$ "
4813 Additionally, more than one package may be specified, in which case the
4814 union of the inputs for the given packages are used. For example, the
4815 command below spawns a shell where all of the dependencies of both Guile
4816 and Emacs are available:
4819 guix environment guile emacs
4822 Sometimes an interactive shell session is not desired. An arbitrary
4823 command may be invoked by placing the @code{--} token to separate the
4824 command from the rest of the arguments:
4827 guix environment guile -- make -j4
4830 In other situations, it is more convenient to specify the list of
4831 packages needed in the environment. For example, the following command
4832 runs @command{python} from an environment containing Python@tie{}2.7 and
4836 guix environment --ad-hoc python2-numpy python-2.7 -- python
4839 Furthermore, one might want the dependencies of a package and also some
4840 additional packages that are not build-time or runtime dependencies, but
4841 are useful when developing nonetheless. Because of this, the
4842 @code{--ad-hoc} flag is positional. Packages appearing before
4843 @code{--ad-hoc} are interpreted as packages whose dependencies will be
4844 added to the environment. Packages appearing after are interpreted as
4845 packages that will be added to the environment directly. For example,
4846 the following command creates a Guix development environment that
4847 additionally includes Git and strace:
4850 guix environment guix --ad-hoc git strace
4853 Sometimes it is desirable to isolate the environment as much as
4854 possible, for maximal purity and reproducibility. In particular, when
4855 using Guix on a host distro that is not GuixSD, it is desirable to
4856 prevent access to @file{/usr/bin} and other system-wide resources from
4857 the development environment. For example, the following command spawns
4858 a Guile REPL in a ``container'' where only the store and the current
4859 working directory are mounted:
4862 guix environment --ad-hoc --container guile -- guile
4866 The @code{--container} option requires Linux-libre 3.19 or newer.
4869 The available options are summarized below.
4872 @item --expression=@var{expr}
4873 @itemx -e @var{expr}
4874 Create an environment for the package or list of packages that
4875 @var{expr} evaluates to.
4877 For example, running:
4880 guix environment -e '(@@ (gnu packages maths) petsc-openmpi)'
4883 starts a shell with the environment for this specific variant of the
4889 guix environment --ad-hoc -e '(@@ (gnu) %base-packages)'
4892 starts a shell with all the GuixSD base packages available.
4894 @item --load=@var{file}
4895 @itemx -l @var{file}
4896 Create an environment for the package or list of packages that the code
4897 within @var{file} evaluates to.
4899 As an example, @var{file} might contain a definition like this
4900 (@pxref{Defining Packages}):
4903 @verbatiminclude environment-gdb.scm
4907 Include all specified packages in the resulting environment, as if an
4908 @i{ad hoc} package were defined with them as inputs. This option is
4909 useful for quickly creating an environment without having to write a
4910 package expression to contain the desired inputs.
4912 For instance, the command:
4915 guix environment --ad-hoc guile guile-sdl -- guile
4918 runs @command{guile} in an environment where Guile and Guile-SDL are
4921 Note that this example implicitly asks for the default output of
4922 @code{guile} and @code{guile-sdl} but it is possible to ask for a
4923 specific output---e.g., @code{glib:bin} asks for the @code{bin} output
4924 of @code{glib} (@pxref{Packages with Multiple Outputs}).
4926 This option may be composed with the default behavior of @command{guix
4927 environment}. Packages appearing before @code{--ad-hoc} are interpreted
4928 as packages whose dependencies will be added to the environment, the
4929 default behavior. Packages appearing after are interpreted as packages
4930 that will be added to the environment directly.
4933 Unset existing environment variables when building the new environment.
4934 This has the effect of creating an environment in which search paths
4935 only contain package inputs.
4937 @item --search-paths
4938 Display the environment variable definitions that make up the
4941 @item --system=@var{system}
4942 @itemx -s @var{system}
4943 Attempt to build for @var{system}---e.g., @code{i686-linux}.
4948 Run @var{command} within an isolated container. The current working
4949 directory outside the container is mapped inside the
4950 container. Additionally, the spawned process runs as the current user
4951 outside the container, but has root privileges in the context of the
4956 For containers, share the network namespace with the host system.
4957 Containers created without this flag only have access to the loopback
4960 @item --expose=@var{source}[=@var{target}]
4961 For containers, expose the file system @var{source} from the host system
4962 as the read-only file system @var{target} within the container. If
4963 @var{target} is not specified, @var{source} is used as the target mount
4964 point in the container.
4966 The example below spawns a Guile REPL in a container in which the user's
4967 home directory is accessible read-only via the @file{/exchange}
4971 guix environment --container --expose=$HOME=/exchange guile -- guile
4974 @item --share=@var{source}[=@var{target}]
4975 For containers, share the file system @var{source} from the host system
4976 as the writable file system @var{target} within the container. If
4977 @var{target} is not specified, @var{source} is used as the target mount
4978 point in the container.
4980 The example below spawns a Guile REPL in a container in which the user's
4981 home directory is accessible for both reading and writing via the
4982 @file{/exchange} directory:
4985 guix environment --container --share=$HOME=/exchange guile -- guile
4989 It also supports all of the common build options that @command{guix
4990 build} supports (@pxref{Invoking guix build, common build options}).
4992 @node Invoking guix publish
4993 @section Invoking @command{guix publish}
4995 The purpose of @command{guix publish} is to enable users to easily share
4996 their store with others, which can then use it as a substitute server
4997 (@pxref{Substitutes}).
4999 When @command{guix publish} runs, it spawns an HTTP server which allows
5000 anyone with network access to obtain substitutes from it. This means
5001 that any machine running Guix can also act as if it were a build farm,
5002 since the HTTP interface is compatible with Hydra, the software behind
5003 the @code{hydra.gnu.org} build farm.
5005 For security, each substitute is signed, allowing recipients to check
5006 their authenticity and integrity (@pxref{Substitutes}). Because
5007 @command{guix publish} uses the system's signing key, which is only
5008 readable by the system administrator, it must be started as root; the
5009 @code{--user} option makes it drop root privileges early on.
5011 The signing key pair must be generated before @command{guix publish} is
5012 launched, using @command{guix archive --generate-key} (@pxref{Invoking
5015 The general syntax is:
5018 guix publish @var{options}@dots{}
5021 Running @command{guix publish} without any additional arguments will
5022 spawn an HTTP server on port 8080:
5028 Once a publishing server has been authorized (@pxref{Invoking guix
5029 archive}), the daemon may download substitutes from it:
5032 guix-daemon --substitute-urls=http://example.org:8080
5035 The following options are available:
5038 @item --port=@var{port}
5039 @itemx -p @var{port}
5040 Listen for HTTP requests on @var{port}.
5042 @item --listen=@var{host}
5043 Listen on the network interface for @var{host}. The default is to
5044 accept connections from any interface.
5046 @item --user=@var{user}
5047 @itemx -u @var{user}
5048 Change privileges to @var{user} as soon as possible---i.e., once the
5049 server socket is open and the signing key has been read.
5051 @item --repl[=@var{port}]
5052 @itemx -r [@var{port}]
5053 Spawn a Guile REPL server (@pxref{REPL Servers,,, guile, GNU Guile
5054 Reference Manual}) on @var{port} (37146 by default). This is used
5055 primarily for debugging a running @command{guix publish} server.
5058 Enabling @command{guix publish} on a GuixSD system is a one-liner: just
5059 add a call to @code{guix-publish-service} in the @code{services} field
5060 of the @code{operating-system} declaration (@pxref{guix-publish-service,
5061 @code{guix-publish-service}}).
5064 @node Invoking guix challenge
5065 @section Invoking @command{guix challenge}
5067 @cindex reproducible builds
5068 @cindex verifiable builds
5070 Do the binaries provided by this server really correspond to the source
5071 code it claims to build? Is this package's build process deterministic?
5072 These are the questions the @command{guix challenge} command attempts to
5075 The former is obviously an important question: Before using a substitute
5076 server (@pxref{Substitutes}), you'd rather @emph{verify} that it
5077 provides the right binaries, and thus @emph{challenge} it. The latter
5078 is what enables the former: If package builds are deterministic, then
5079 independent builds of the package should yield the exact same result,
5080 bit for bit; if a server provides a binary different from the one
5081 obtained locally, it may be either corrupt or malicious.
5083 We know that the hash that shows up in @file{/gnu/store} file names is
5084 the hash of all the inputs of the process that built the file or
5085 directory---compilers, libraries, build scripts,
5086 etc. (@pxref{Introduction}). Assuming deterministic build processes,
5087 one store file name should map to exactly one build output.
5088 @command{guix challenge} checks whether there is, indeed, a single
5089 mapping by comparing the build outputs of several independent builds of
5090 any given store item.
5092 The command's output looks like this:
5095 $ guix challenge --substitute-urls="http://hydra.gnu.org http://guix.example.org"
5096 updating list of substitutes from 'http://hydra.gnu.org'... 100.0%
5097 updating list of substitutes from 'http://guix.example.org'... 100.0%
5098 /gnu/store/@dots{}-openssl-1.0.2d contents differ:
5099 local hash: 0725l22r5jnzazaacncwsvp9kgf42266ayyp814v7djxs7nk963q
5100 http://hydra.gnu.org/nar/@dots{}-openssl-1.0.2d: 0725l22r5jnzazaacncwsvp9kgf42266ayyp814v7djxs7nk963q
5101 http://guix.example.org/nar/@dots{}-openssl-1.0.2d: 1zy4fmaaqcnjrzzajkdn3f5gmjk754b43qkq47llbyak9z0qjyim
5102 /gnu/store/@dots{}-git-2.5.0 contents differ:
5103 local hash: 00p3bmryhjxrhpn2gxs2fy0a15lnip05l97205pgbk5ra395hyha
5104 http://hydra.gnu.org/nar/@dots{}-git-2.5.0: 069nb85bv4d4a6slrwjdy8v1cn4cwspm3kdbmyb81d6zckj3nq9f
5105 http://guix.example.org/nar/@dots{}-git-2.5.0: 0mdqa9w1p6cmli6976v4wi0sw9r4p5prkj7lzfd1877wk11c9c73
5106 /gnu/store/@dots{}-pius-2.1.1 contents differ:
5107 local hash: 0k4v3m9z1zp8xzzizb7d8kjj72f9172xv078sq4wl73vnq9ig3ax
5108 http://hydra.gnu.org/nar/@dots{}-pius-2.1.1: 0k4v3m9z1zp8xzzizb7d8kjj72f9172xv078sq4wl73vnq9ig3ax
5109 http://guix.example.org/nar/@dots{}-pius-2.1.1: 1cy25x1a4fzq5rk0pmvc8xhwyffnqz95h2bpvqsz2mpvlbccy0gs
5113 In this example, @command{guix challenge} first scans the store to
5114 determine the set of locally-built derivations---as opposed to store
5115 items that were downloaded from a substitute server---and then queries
5116 all the substitute servers. It then reports those store items for which
5117 the servers obtained a result different from the local build.
5119 @cindex non-determinism, in package builds
5120 As an example, @code{guix.example.org} always gets a different answer.
5121 Conversely, @code{hydra.gnu.org} agrees with local builds, except in the
5122 case of Git. This might indicate that the build process of Git is
5123 non-deterministic, meaning that its output varies as a function of
5124 various things that Guix does not fully control, in spite of building
5125 packages in isolated environments (@pxref{Features}). Most common
5126 sources of non-determinism include the addition of timestamps in build
5127 results, the inclusion of random numbers, and directory listings sorted
5128 by inode number. See @uref{http://reproducible.debian.net/howto/}, for
5131 To find out what's wrong with this Git binary, we can do something along
5132 these lines (@pxref{Invoking guix archive}):
5135 $ wget -q -O - http://hydra.gnu.org/nar/@dots{}-git-2.5.0 \
5136 | guix archive -x /tmp/git
5137 $ diff -ur --no-dereference /gnu/store/@dots{}-git.2.5.0 /tmp/git
5140 This command shows the difference between the files resulting from the
5141 local build, and the files resulting from the build on
5142 @code{hydra.gnu.org} (@pxref{Overview, Comparing and Merging Files,,
5143 diffutils, Comparing and Merging Files}). The @command{diff} command
5144 works great for text files. When binary files differ, a better option
5145 is @uref{http://diffoscope.org/, Diffoscope}, a tool that helps
5146 visualize differences for all kinds of files.
5148 Once you've done that work, you can tell whether the differences are due
5149 to a non-deterministic build process or to a malicious server. We try
5150 hard to remove sources of non-determinism in packages to make it easier
5151 to verify substitutes, but of course, this is a process, one that
5152 involves not just Guix but a large part of the free software community.
5153 In the meantime, @command{guix challenge} is one tool to help address
5156 If you are writing packages for Guix, you are encouraged to check
5157 whether @code{hydra.gnu.org} and other substitute servers obtain the
5158 same build result as you did with:
5161 $ guix challenge @var{package}
5165 ... where @var{package} is a package specification such as
5166 @code{guile-2.0} or @code{glibc:debug}.
5168 The general syntax is:
5171 guix challenge @var{options} [@var{packages}@dots{}]
5174 The one option that matters is:
5178 @item --substitute-urls=@var{urls}
5179 Consider @var{urls} the whitespace-separated list of substitute source
5185 @node Invoking guix container
5186 @section Invoking @command{guix container}
5190 As of version @value{VERSION}, this tool is experimental. The interface
5191 is subject to radical change in the future.
5194 The purpose of @command{guix container} is to manipulate processes
5195 running within an isolated environment, commonly known as a
5196 ``container'', typically created by the @command{guix environment}
5197 (@pxref{Invoking guix environment}) and @command{guix system container}
5198 (@pxref{Invoking guix system}) commands.
5200 The general syntax is:
5203 guix container @var{action} @var{options}@dots{}
5206 @var{action} specifies the operation to perform with a container, and
5207 @var{options} specifies the context-specific arguments for the action.
5209 The following actions are available:
5213 Execute a command within the context of a running container.
5218 guix container exec @var{pid} @var{program} @var{arguments}@dots{}
5221 @var{pid} specifies the process ID of the running container.
5222 @var{program} specifies an executable file name within the container's
5223 root file system. @var{arguments} are the additional options that will
5224 be passed to @var{program}.
5226 The following command launches an interactive login shell inside a
5227 GuixSD container, started by @command{guix system container}, and whose
5231 guix container exec 9001 /run/current-system/profile/bin/bash --login
5234 Note that the @var{pid} cannot be the parent process of a container. It
5235 must be the container's PID 1 or one of its child processes.
5239 @c *********************************************************************
5240 @node GNU Distribution
5241 @chapter GNU Distribution
5243 @cindex Guix System Distribution
5245 Guix comes with a distribution of the GNU system consisting entirely of
5246 free software@footnote{The term ``free'' here refers to the
5247 @url{http://www.gnu.org/philosophy/free-sw.html,freedom provided to
5248 users of that software}.}. The
5249 distribution can be installed on its own (@pxref{System Installation}),
5250 but it is also possible to install Guix as a package manager on top of
5251 an installed GNU/Linux system (@pxref{Installation}). To distinguish
5252 between the two, we refer to the standalone distribution as the Guix
5253 System Distribution, or GuixSD.
5255 The distribution provides core GNU packages such as GNU libc, GCC, and
5256 Binutils, as well as many GNU and non-GNU applications. The complete
5257 list of available packages can be browsed
5258 @url{http://www.gnu.org/software/guix/packages,on-line} or by
5259 running @command{guix package} (@pxref{Invoking guix package}):
5262 guix package --list-available
5265 Our goal has been to provide a practical 100% free software distribution of
5266 Linux-based and other variants of GNU, with a focus on the promotion and
5267 tight integration of GNU components, and an emphasis on programs and
5268 tools that help users exert that freedom.
5270 Packages are currently available on the following platforms:
5275 Intel/AMD @code{x86_64} architecture, Linux-Libre kernel;
5278 Intel 32-bit architecture (IA32), Linux-Libre kernel;
5281 ARMv7-A architecture with hard float, Thumb-2 and NEON,
5282 using the EABI hard-float ABI, and Linux-Libre kernel.
5284 @item mips64el-linux
5285 little-endian 64-bit MIPS processors, specifically the Loongson series,
5286 n32 application binary interface (ABI), and Linux-Libre kernel.
5290 GuixSD itself is currently only available on @code{i686} and @code{x86_64}.
5293 For information on porting to other architectures or kernels,
5297 * System Installation:: Installing the whole operating system.
5298 * System Configuration:: Configuring the operating system.
5299 * Installing Debugging Files:: Feeding the debugger.
5300 * Security Updates:: Deploying security fixes quickly.
5301 * Package Modules:: Packages from the programmer's viewpoint.
5302 * Packaging Guidelines:: Growing the distribution.
5303 * Bootstrapping:: GNU/Linux built from scratch.
5304 * Porting:: Targeting another platform or kernel.
5307 Building this distribution is a cooperative effort, and you are invited
5308 to join! @xref{Contributing}, for information about how you can help.
5310 @node System Installation
5311 @section System Installation
5313 @cindex Guix System Distribution
5314 This section explains how to install the Guix System Distribution
5315 on a machine. The Guix package manager can
5316 also be installed on top of a running GNU/Linux system,
5317 @pxref{Installation}.
5320 @c This paragraph is for people reading this from tty2 of the
5321 @c installation image.
5322 You're reading this documentation with an Info reader. For details on
5323 how to use it, hit the @key{RET} key (``return'' or ``enter'') on the
5324 link that follows: @pxref{Help,,, info, Info: An Introduction}. Hit
5325 @kbd{l} afterwards to come back here.
5328 @subsection Limitations
5330 As of version @value{VERSION}, the Guix System Distribution (GuixSD) is
5331 not production-ready. It may contain bugs and lack important
5332 features. Thus, if you are looking for a stable production system that
5333 respects your freedom as a computer user, a good solution at this point
5334 is to consider @url{http://www.gnu.org/distros/free-distros.html, one of
5335 more established GNU/Linux distributions}. We hope you can soon switch
5336 to the GuixSD without fear, of course. In the meantime, you can
5337 also keep using your distribution and try out the package manager on top
5338 of it (@pxref{Installation}).
5340 Before you proceed with the installation, be aware of the following
5341 noteworthy limitations applicable to version @value{VERSION}:
5345 The installation process does not include a graphical user interface and
5346 requires familiarity with GNU/Linux (see the following subsections to
5347 get a feel of what that means.)
5350 The system does not yet provide full GNOME and KDE desktops. Xfce and
5351 Enlightenment are available though, if graphical desktop environments
5352 are your thing, as well as a number of X11 window managers.
5355 Support for the Logical Volume Manager (LVM) is missing.
5358 Few system services are currently supported out-of-the-box
5362 More than 2,000 packages are available, but you may
5363 occasionally find that a useful package is missing.
5366 You've been warned. But more than a disclaimer, this is an invitation
5367 to report issues (and success stories!), and join us in improving it.
5368 @xref{Contributing}, for more info.
5370 @subsection USB Stick Installation
5372 An installation image for USB sticks can be downloaded from
5373 @indicateurl{ftp://alpha.gnu.org/gnu/guix/guixsd-usb-install-@value{VERSION}.@var{system}.xz},
5374 where @var{system} is one of:
5378 for a GNU/Linux system on Intel/AMD-compatible 64-bit CPUs;
5381 for a 32-bit GNU/Linux system on Intel-compatible CPUs.
5384 This image contains a single partition with the tools necessary for an
5385 installation. It is meant to be copied @emph{as is} to a large-enough
5388 To copy the image to a USB stick, follow these steps:
5392 Decompress the image using the @command{xz} command:
5395 xz -d guixsd-usb-install-@value{VERSION}.@var{system}.xz
5399 Insert a USB stick of 1@tie{}GiB or more in your machine, and determine
5400 its device name. Assuming that USB stick is known as @file{/dev/sdX},
5401 copy the image with:
5404 dd if=guixsd-usb-install-@value{VERSION}.x86_64 of=/dev/sdX
5407 Access to @file{/dev/sdX} usually requires root privileges.
5410 Once this is done, you should be able to reboot the system and boot from
5411 the USB stick. The latter usually requires you to get in the BIOS' boot
5412 menu, where you can choose to boot from the USB stick.
5414 @subsection Preparing for Installation
5416 Once you have successfully booted the image on the USB stick, you should
5417 end up with a root prompt. Several console TTYs are configured and can
5418 be used to run commands as root. TTY2 shows this documentation,
5419 browsable using the Info reader commands (@pxref{Help,,, info, Info: An
5420 Introduction}). The installation system runs the GPM mouse daemon,
5421 which allows you to select text with the left mouse button and to paste
5422 it with the middle button.
5424 To install the system, you would:
5429 Configure the network, by running:
5432 ifconfig eno1 up && dhclient eno1
5435 to get an automatically assigned IP address from the wired
5436 network interface controller@footnote{
5437 @c http://cgit.freedesktop.org/systemd/systemd/tree/src/udev/udev-builtin-net_id.c#n20
5438 The name @code{eno1} is for the first on-board Ethernet controller. The
5439 interface name for an Ethernet controller that is in the first slot of
5440 the first PCI bus, for instance, would be @code{enp1s0}. Use
5441 @command{ifconfig -a} to list all the available network interfaces.},
5442 or using the @command{ifconfig} command.
5444 The system automatically loads drivers for your network interface
5447 Setting up network access is almost always a requirement because the
5448 image does not contain all the software and tools that may be needed.
5451 Unless this has already been done, you must partition, and then format
5452 the target partition.
5454 Preferably, assign partitions a label so that you can easily and
5455 reliably refer to them in @code{file-system} declarations (@pxref{File
5456 Systems}). This is typically done using the @code{-L} option of
5457 @command{mkfs.ext4} and related commands.
5459 @c FIXME: Uncomment this once GRUB fully supports encrypted roots.
5460 @c A typical command sequence may be:
5464 @c @dots{} Create partitions etc.@dots{}
5465 @c # cryptsetup luksFormat /dev/sdX1
5466 @c # cryptsetup open --type luks /dev/sdX1 my-partition
5467 @c # mkfs.ext4 -L my-root /dev/mapper/my-partition
5470 The installation image includes Parted (@pxref{Overview,,, parted, GNU
5471 Parted User Manual}), @command{fdisk}, Cryptsetup/LUKS for disk
5472 encryption, and e2fsprogs, the suite of tools to manipulate
5473 ext2/ext3/ext4 file systems.
5476 Once that is done, mount the target root partition under @file{/mnt}.
5479 Lastly, run @code{deco start cow-store /mnt}.
5481 This will make @file{/gnu/store} copy-on-write, such that packages added
5482 to it during the installation phase will be written to the target disk
5483 rather than kept in memory.
5488 @subsection Proceeding with the Installation
5490 With the target partitions ready, you now have to edit a file and
5491 provide the declaration of the operating system to be installed. To
5492 that end, the installation system comes with two text editors: GNU nano
5493 (@pxref{Top,,, nano, GNU nano Manual}), and GNU Zile, an Emacs clone.
5494 It is better to store that file on the target root file system, say, as
5495 @file{/mnt/etc/config.scm}.
5497 @xref{Using the Configuration System}, for examples of operating system
5498 configurations. These examples are available under
5499 @file{/etc/configuration} in the installation image, so you can copy
5500 them and use them as a starting point for your own configuration.
5502 Once you are done preparing the configuration file, the new system must
5503 be initialized (remember that the target root file system is mounted
5507 guix system init /mnt/etc/config.scm /mnt
5511 This will copy all the necessary files, and install GRUB on
5512 @file{/dev/sdX}, unless you pass the @option{--no-grub} option. For
5513 more information, @pxref{Invoking guix system}. This command may trigger
5514 downloads or builds of missing packages, which can take some time.
5516 Once that command has completed---and hopefully succeeded!---you can run
5517 @command{reboot} and boot into the new system. The @code{root} password
5518 in the new system is initially empty; other users' passwords need to be
5519 initialized by running the @command{passwd} command as @code{root},
5520 unless your configuration specifies otherwise
5521 (@pxref{user-account-password, user account passwords}).
5523 Join us on @code{#guix} on the Freenode IRC network or on
5524 @file{guix-devel@@gnu.org} to share your experience---good or not so
5527 @subsection Building the Installation Image
5529 The installation image described above was built using the @command{guix
5530 system} command, specifically:
5533 guix system disk-image --image-size=850MiB gnu/system/install.scm
5536 @xref{Invoking guix system}, for more information. See
5537 @file{gnu/system/install.scm} in the source tree for more information
5538 about the installation image.
5540 @node System Configuration
5541 @section System Configuration
5543 @cindex system configuration
5544 The Guix System Distribution supports a consistent whole-system configuration
5545 mechanism. By that we mean that all aspects of the global system
5546 configuration---such as the available system services, timezone and
5547 locale settings, user accounts---are declared in a single place. Such
5548 a @dfn{system configuration} can be @dfn{instantiated}---i.e., effected.
5550 One of the advantages of putting all the system configuration under the
5551 control of Guix is that it supports transactional system upgrades, and
5552 makes it possible to roll-back to a previous system instantiation,
5553 should something go wrong with the new one (@pxref{Features}). Another
5554 one is that it makes it easy to replicate the exact same configuration
5555 across different machines, or at different points in time, without
5556 having to resort to additional administration tools layered on top of
5557 the system's own tools.
5558 @c Yes, we're talking of Puppet, Chef, & co. here. ↑
5560 This section describes this mechanism. First we focus on the system
5561 administrator's viewpoint---explaining how the system is configured and
5562 instantiated. Then we show how this mechanism can be extended, for
5563 instance to support new system services.
5566 * Using the Configuration System:: Customizing your GNU system.
5567 * operating-system Reference:: Detail of operating-system declarations.
5568 * File Systems:: Configuring file system mounts.
5569 * Mapped Devices:: Block device extra processing.
5570 * User Accounts:: Specifying user accounts.
5571 * Locales:: Language and cultural convention settings.
5572 * Services:: Specifying system services.
5573 * Setuid Programs:: Programs running with root privileges.
5574 * X.509 Certificates:: Authenticating HTTPS servers.
5575 * Name Service Switch:: Configuring libc's name service switch.
5576 * Initial RAM Disk:: Linux-Libre bootstrapping.
5577 * GRUB Configuration:: Configuring the boot loader.
5578 * Invoking guix system:: Instantiating a system configuration.
5579 * Defining Services:: Adding new service definitions.
5582 @node Using the Configuration System
5583 @subsection Using the Configuration System
5585 The operating system is configured by providing an
5586 @code{operating-system} declaration in a file that can then be passed to
5587 the @command{guix system} command (@pxref{Invoking guix system}). A
5588 simple setup, with the default system services, the default Linux-Libre
5589 kernel, initial RAM disk, and boot loader looks like this:
5591 @findex operating-system
5593 @include os-config-bare-bones.texi
5596 This example should be self-describing. Some of the fields defined
5597 above, such as @code{host-name} and @code{bootloader}, are mandatory.
5598 Others, such as @code{packages} and @code{services}, can be omitted, in
5599 which case they get a default value.
5601 @vindex %base-packages
5602 The @code{packages} field lists
5603 packages that will be globally visible on the system, for all user
5604 accounts---i.e., in every user's @code{PATH} environment variable---in
5605 addition to the per-user profiles (@pxref{Invoking guix package}). The
5606 @var{%base-packages} variable provides all the tools one would expect
5607 for basic user and administrator tasks---including the GNU Core
5608 Utilities, the GNU Networking Utilities, the GNU Zile lightweight text
5609 editor, @command{find}, @command{grep}, etc. The example above adds
5610 tcpdump to those, taken from the @code{(gnu packages admin)} module
5611 (@pxref{Package Modules}).
5613 @findex specification->package
5614 Referring to packages by variable name, like @var{tcpdump} above, has
5615 the advantage of being unambiguous; it also allows typos and such to be
5616 diagnosed right away as ``unbound variables''. The downside is that one
5617 needs to know which module defines which package, and to augment the
5618 @code{use-package-modules} line accordingly. To avoid that, one can use
5619 the @code{specification->package} procedure of the @code{(gnu packages)}
5620 module, which returns the best package for a given name or name and
5624 (use-modules (gnu packages))
5628 (packages (append (map specification->package
5629 '("tcpdump" "htop" "gnupg-2.0"))
5633 @vindex %base-services
5634 The @code{services} field lists @dfn{system services} to be made
5635 available when the system starts (@pxref{Services}).
5636 The @code{operating-system} declaration above specifies that, in
5637 addition to the basic services, we want the @command{lshd} secure shell
5638 daemon listening on port 2222 (@pxref{Networking Services,
5639 @code{lsh-service}}). Under the hood,
5640 @code{lsh-service} arranges so that @code{lshd} is started with the
5641 right command-line options, possibly with supporting configuration files
5642 generated as needed (@pxref{Defining Services}).
5644 @cindex customization, of services
5645 @findex modify-services
5646 Occasionally, instead of using the base services as is, you will want to
5647 customize them. For instance, to change the configuration of
5648 @code{guix-daemon} and Mingetty (the console log-in), you may write the
5649 following instead of @var{%base-services}:
5652 (modify-services %base-services
5653 (guix-service-type config =>
5656 (use-substitutes? #f)
5657 (extra-options '("--gc-keep-outputs"))))
5658 (mingetty-service-type config =>
5659 (mingetty-configuration
5661 (motd (plain-file "motd" "Hi there!")))))
5665 The effect here is to change the options passed to @command{guix-daemon}
5666 when it is started, as well as the ``message of the day'' that appears
5667 when logging in at the console. @xref{Service Reference,
5668 @code{modify-services}}, for more on that.
5670 The configuration for a typical ``desktop'' usage, with the X11 display
5671 server, a desktop environment, network management, power management, and
5672 more, would look like this:
5675 @include os-config-desktop.texi
5678 @xref{Desktop Services}, for the exact list of services provided by
5679 @var{%desktop-services}. @xref{X.509 Certificates}, for background
5680 information about the @code{nss-certs} package that is used here.
5681 @xref{operating-system Reference}, for details about all the available
5682 @code{operating-system} fields.
5684 Assuming the above snippet is stored in the @file{my-system-config.scm}
5685 file, the @command{guix system reconfigure my-system-config.scm} command
5686 instantiates that configuration, and makes it the default GRUB boot
5687 entry (@pxref{Invoking guix system}).
5689 The normal way to change the system's configuration is by updating this
5690 file and re-running @command{guix system reconfigure}. One should never
5691 have to touch files in @command{/etc} or to run commands that modify the
5692 system state such as @command{useradd} or @command{grub-install}. In
5693 fact, you must avoid that since that would not only void your warranty
5694 but also prevent you from rolling back to previous versions of your
5695 system, should you ever need to.
5697 @cindex roll-back, of the operating system
5698 Speaking of roll-back, each time you run @command{guix system
5699 reconfigure}, a new @dfn{generation} of the system is created---without
5700 modifying or deleting previous generations. Old system generations get
5701 an entry in the GRUB boot menu, allowing you to boot them in case
5702 something went wrong with the latest generation. Reassuring, no? The
5703 @command{guix system list-generations} command lists the system
5704 generations available on disk.
5706 At the Scheme level, the bulk of an @code{operating-system} declaration
5707 is instantiated with the following monadic procedure (@pxref{The Store
5710 @deffn {Monadic Procedure} operating-system-derivation os
5711 Return a derivation that builds @var{os}, an @code{operating-system}
5712 object (@pxref{Derivations}).
5714 The output of the derivation is a single directory that refers to all
5715 the packages, configuration files, and other supporting files needed to
5716 instantiate @var{os}.
5719 @node operating-system Reference
5720 @subsection @code{operating-system} Reference
5722 This section summarizes all the options available in
5723 @code{operating-system} declarations (@pxref{Using the Configuration
5726 @deftp {Data Type} operating-system
5727 This is the data type representing an operating system configuration.
5728 By that, we mean all the global system configuration, not per-user
5729 configuration (@pxref{Using the Configuration System}).
5732 @item @code{kernel} (default: @var{linux-libre})
5733 The package object of the operating system kernel to use@footnote{Currently
5734 only the Linux-libre kernel is supported. In the future, it will be
5735 possible to use the GNU@tie{}Hurd.}.
5737 @item @code{kernel-arguments} (default: @code{'()})
5738 List of strings or gexps representing additional arguments to pass on
5739 the kernel's command-line---e.g., @code{("console=ttyS0")}.
5741 @item @code{bootloader}
5742 The system bootloader configuration object. @xref{GRUB Configuration}.
5744 @item @code{initrd} (default: @code{base-initrd})
5745 A two-argument monadic procedure that returns an initial RAM disk for
5746 the Linux kernel. @xref{Initial RAM Disk}.
5748 @item @code{firmware} (default: @var{%base-firmware})
5750 List of firmware packages loadable by the operating system kernel.
5752 The default includes firmware needed for Atheros-based WiFi devices
5753 (Linux-libre module @code{ath9k}.)
5755 @item @code{host-name}
5758 @item @code{hosts-file}
5760 A file-like object (@pxref{G-Expressions, file-like objects}) for use as
5761 @file{/etc/hosts} (@pxref{Host Names,,, libc, The GNU C Library
5762 Reference Manual}). The default is a file with entries for
5763 @code{localhost} and @var{host-name}.
5765 @item @code{mapped-devices} (default: @code{'()})
5766 A list of mapped devices. @xref{Mapped Devices}.
5768 @item @code{file-systems}
5769 A list of file systems. @xref{File Systems}.
5771 @item @code{swap-devices} (default: @code{'()})
5772 @cindex swap devices
5773 A list of strings identifying devices to be used for ``swap space''
5774 (@pxref{Memory Concepts,,, libc, The GNU C Library Reference Manual}).
5775 For example, @code{'("/dev/sda3")}.
5777 @item @code{users} (default: @code{%base-user-accounts})
5778 @itemx @code{groups} (default: @var{%base-groups})
5779 List of user accounts and groups. @xref{User Accounts}.
5781 @item @code{skeletons} (default: @code{(default-skeletons)})
5782 A monadic list of pairs of target file name and files. These are the
5783 files that will be used as skeletons as new accounts are created.
5785 For instance, a valid value may look like this:
5788 (mlet %store-monad ((bashrc (text-file "bashrc" "\
5789 export PATH=$HOME/.guix-profile/bin")))
5790 (return `((".bashrc" ,bashrc))))
5793 @item @code{issue} (default: @var{%default-issue})
5794 A string denoting the contents of the @file{/etc/issue} file, which is
5795 what displayed when users log in on a text console.
5797 @item @code{packages} (default: @var{%base-packages})
5798 The set of packages installed in the global profile, which is accessible
5799 at @file{/run/current-system/profile}.
5801 The default set includes core utilities, but it is good practice to
5802 install non-core utilities in user profiles (@pxref{Invoking guix
5805 @item @code{timezone}
5806 A timezone identifying string---e.g., @code{"Europe/Paris"}.
5808 @item @code{locale} (default: @code{"en_US.utf8"})
5809 The name of the default locale (@pxref{Locale Names,,, libc, The GNU C
5810 Library Reference Manual}). @xref{Locales}, for more information.
5812 @item @code{locale-definitions} (default: @var{%default-locale-definitions})
5813 The list of locale definitions to be compiled and that may be used at
5814 run time. @xref{Locales}.
5816 @item @code{locale-libcs} (default: @code{(list @var{glibc})})
5817 The list of GNU@tie{}libc packages whose locale data and tools are used
5818 to build the locale definitions. @xref{Locales}, for compatibility
5819 considerations that justify this option.
5821 @item @code{name-service-switch} (default: @var{%default-nss})
5822 Configuration of libc's name service switch (NSS)---a
5823 @code{<name-service-switch>} object. @xref{Name Service Switch}, for
5826 @item @code{services} (default: @var{%base-services})
5827 A list of service objects denoting system services. @xref{Services}.
5829 @item @code{pam-services} (default: @code{(base-pam-services)})
5831 @cindex pluggable authentication modules
5832 Linux @dfn{pluggable authentication module} (PAM) services.
5833 @c FIXME: Add xref to PAM services section.
5835 @item @code{setuid-programs} (default: @var{%setuid-programs})
5836 List of string-valued G-expressions denoting setuid programs.
5837 @xref{Setuid Programs}.
5839 @item @code{sudoers-file} (default: @var{%sudoers-specification})
5840 @cindex sudoers file
5841 The contents of the @file{/etc/sudoers} file as a file-like object
5842 (@pxref{G-Expressions, @code{local-file} and @code{plain-file}}).
5844 This file specifies which users can use the @command{sudo} command, what
5845 they are allowed to do, and what privileges they may gain. The default
5846 is that only @code{root} and members of the @code{wheel} group may use
5853 @subsection File Systems
5855 The list of file systems to be mounted is specified in the
5856 @code{file-systems} field of the operating system's declaration
5857 (@pxref{Using the Configuration System}). Each file system is declared
5858 using the @code{file-system} form, like this:
5862 (mount-point "/home")
5863 (device "/dev/sda3")
5867 As usual, some of the fields are mandatory---those shown in the example
5868 above---while others can be omitted. These are described below.
5870 @deftp {Data Type} file-system
5871 Objects of this type represent file systems to be mounted. They
5872 contain the following members:
5876 This is a string specifying the type of the file system---e.g.,
5879 @item @code{mount-point}
5880 This designates the place where the file system is to be mounted.
5883 This names the ``source'' of the file system. By default it is the name
5884 of a node under @file{/dev}, but its meaning depends on the @code{title}
5885 field described below.
5887 @item @code{title} (default: @code{'device})
5888 This is a symbol that specifies how the @code{device} field is to be
5891 When it is the symbol @code{device}, then the @code{device} field is
5892 interpreted as a file name; when it is @code{label}, then @code{device}
5893 is interpreted as a partition label name; when it is @code{uuid},
5894 @code{device} is interpreted as a partition unique identifier (UUID).
5896 UUIDs may be converted from their string representation (as shown by the
5897 @command{tune2fs -l} command) using the @code{uuid} form, like this:
5901 (mount-point "/home")
5904 (device (uuid "4dab5feb-d176-45de-b287-9b0a6e4c01cb")))
5907 The @code{label} and @code{uuid} options offer a way to refer to disk
5908 partitions without having to hard-code their actual device
5909 name@footnote{Note that, while it is tempting to use
5910 @file{/dev/disk/by-uuid} and similar device names to achieve the same
5911 result, this is not recommended: These special device nodes are created
5912 by the udev daemon and may be unavailable at the time the device is
5915 However, when a file system's source is a mapped device (@pxref{Mapped
5916 Devices}), its @code{device} field @emph{must} refer to the mapped
5917 device name---e.g., @file{/dev/mapper/root-partition}---and consequently
5918 @code{title} must be set to @code{'device}. This is required so that
5919 the system knows that mounting the file system depends on having the
5920 corresponding device mapping established.
5922 @item @code{flags} (default: @code{'()})
5923 This is a list of symbols denoting mount flags. Recognized flags
5924 include @code{read-only}, @code{bind-mount}, @code{no-dev} (disallow
5925 access to special files), @code{no-suid} (ignore setuid and setgid
5926 bits), and @code{no-exec} (disallow program execution.)
5928 @item @code{options} (default: @code{#f})
5929 This is either @code{#f}, or a string denoting mount options.
5931 @item @code{needed-for-boot?} (default: @code{#f})
5932 This Boolean value indicates whether the file system is needed when
5933 booting. If that is true, then the file system is mounted when the
5934 initial RAM disk (initrd) is loaded. This is always the case, for
5935 instance, for the root file system.
5937 @item @code{check?} (default: @code{#t})
5938 This Boolean indicates whether the file system needs to be checked for
5939 errors before being mounted.
5941 @item @code{create-mount-point?} (default: @code{#f})
5942 When true, the mount point is created if it does not exist yet.
5944 @item @code{dependencies} (default: @code{'()})
5945 This is a list of @code{<file-system>} objects representing file systems
5946 that must be mounted before (and unmounted after) this one.
5948 As an example, consider a hierarchy of mounts: @file{/sys/fs/cgroup} is
5949 a dependency of @file{/sys/fs/cgroup/cpu} and
5950 @file{/sys/fs/cgroup/memory}.
5955 The @code{(gnu system file-systems)} exports the following useful
5958 @defvr {Scheme Variable} %base-file-systems
5959 These are essential file systems that are required on normal systems,
5960 such as @var{%pseudo-terminal-file-system} and @var{%immutable-store} (see
5961 below.) Operating system declarations should always contain at least
5965 @defvr {Scheme Variable} %pseudo-terminal-file-system
5966 This is the file system to be mounted as @file{/dev/pts}. It supports
5967 @dfn{pseudo-terminals} created @i{via} @code{openpty} and similar
5968 functions (@pxref{Pseudo-Terminals,,, libc, The GNU C Library Reference
5969 Manual}). Pseudo-terminals are used by terminal emulators such as
5973 @defvr {Scheme Variable} %shared-memory-file-system
5974 This file system is mounted as @file{/dev/shm} and is used to support
5975 memory sharing across processes (@pxref{Memory-mapped I/O,
5976 @code{shm_open},, libc, The GNU C Library Reference Manual}).
5979 @defvr {Scheme Variable} %immutable-store
5980 This file system performs a read-only ``bind mount'' of
5981 @file{/gnu/store}, making it read-only for all the users including
5982 @code{root}. This prevents against accidental modification by software
5983 running as @code{root} or by system administrators.
5985 The daemon itself is still able to write to the store: it remounts it
5986 read-write in its own ``name space.''
5989 @defvr {Scheme Variable} %binary-format-file-system
5990 The @code{binfmt_misc} file system, which allows handling of arbitrary
5991 executable file types to be delegated to user space. This requires the
5992 @code{binfmt.ko} kernel module to be loaded.
5995 @defvr {Scheme Variable} %fuse-control-file-system
5996 The @code{fusectl} file system, which allows unprivileged users to mount
5997 and unmount user-space FUSE file systems. This requires the
5998 @code{fuse.ko} kernel module to be loaded.
6001 @node Mapped Devices
6002 @subsection Mapped Devices
6004 @cindex device mapping
6005 @cindex mapped devices
6006 The Linux kernel has a notion of @dfn{device mapping}: a block device,
6007 such as a hard disk partition, can be @dfn{mapped} into another device,
6008 with additional processing over the data that flows through
6009 it@footnote{Note that the GNU@tie{}Hurd makes no difference between the
6010 concept of a ``mapped device'' and that of a file system: both boil down
6011 to @emph{translating} input/output operations made on a file to
6012 operations on its backing store. Thus, the Hurd implements mapped
6013 devices, like file systems, using the generic @dfn{translator} mechanism
6014 (@pxref{Translators,,, hurd, The GNU Hurd Reference Manual}).}. A
6015 typical example is encryption device mapping: all writes to the mapped
6016 device are encrypted, and all reads are deciphered, transparently.
6018 Mapped devices are declared using the @code{mapped-device} form:
6022 (source "/dev/sda3")
6024 (type luks-device-mapping))
6028 @cindex disk encryption
6030 This example specifies a mapping from @file{/dev/sda3} to
6031 @file{/dev/mapper/home} using LUKS---the
6032 @url{http://code.google.com/p/cryptsetup,Linux Unified Key Setup}, a
6033 standard mechanism for disk encryption. The @file{/dev/mapper/home}
6034 device can then be used as the @code{device} of a @code{file-system}
6035 declaration (@pxref{File Systems}). The @code{mapped-device} form is
6038 @deftp {Data Type} mapped-device
6039 Objects of this type represent device mappings that will be made when
6040 the system boots up.
6044 This string specifies the name of the block device to be mapped, such as
6048 This string specifies the name of the mapping to be established. For
6049 example, specifying @code{"my-partition"} will lead to the creation of
6050 the @code{"/dev/mapper/my-partition"} device.
6053 This must be a @code{mapped-device-kind} object, which specifies how
6054 @var{source} is mapped to @var{target}.
6058 @defvr {Scheme Variable} luks-device-mapping
6059 This defines LUKS block device encryption using the @command{cryptsetup}
6060 command, from the same-named package. This relies on the
6061 @code{dm-crypt} Linux kernel module.
6065 @subsection User Accounts
6067 User accounts and groups are entirely managed through the
6068 @code{operating-system} declaration. They are specified with the
6069 @code{user-account} and @code{user-group} forms:
6075 (supplementary-groups '("wheel" ;allow use of sudo, etc.
6077 "video" ;video devices such as webcams
6078 "cdrom")) ;the good ol' CD-ROM
6079 (comment "Bob's sister")
6080 (home-directory "/home/alice"))
6083 When booting or upon completion of @command{guix system reconfigure},
6084 the system ensures that only the user accounts and groups specified in
6085 the @code{operating-system} declaration exist, and with the specified
6086 properties. Thus, account or group creations or modifications made by
6087 directly invoking commands such as @command{useradd} are lost upon
6088 reconfiguration or reboot. This ensures that the system remains exactly
6091 @deftp {Data Type} user-account
6092 Objects of this type represent user accounts. The following members may
6097 The name of the user account.
6100 This is the name (a string) or identifier (a number) of the user group
6101 this account belongs to.
6103 @item @code{supplementary-groups} (default: @code{'()})
6104 Optionally, this can be defined as a list of group names that this
6107 @item @code{uid} (default: @code{#f})
6108 This is the user ID for this account (a number), or @code{#f}. In the
6109 latter case, a number is automatically chosen by the system when the
6112 @item @code{comment} (default: @code{""})
6113 A comment about the account, such as the account's owner full name.
6115 @item @code{home-directory}
6116 This is the name of the home directory for the account.
6118 @item @code{shell} (default: Bash)
6119 This is a G-expression denoting the file name of a program to be used as
6120 the shell (@pxref{G-Expressions}).
6122 @item @code{system?} (default: @code{#f})
6123 This Boolean value indicates whether the account is a ``system''
6124 account. System accounts are sometimes treated specially; for instance,
6125 graphical login managers do not list them.
6127 @anchor{user-account-password}
6128 @item @code{password} (default: @code{#f})
6129 You would normally leave this field to @code{#f}, initialize user
6130 passwords as @code{root} with the @command{passwd} command, and then let
6131 users change it with @command{passwd}. Passwords set with
6132 @command{passwd} are of course preserved across reboot and
6135 If you @emph{do} want to have a preset password for an account, then
6136 this field must contain the encrypted password, as a string.
6137 @xref{crypt,,, libc, The GNU C Library Reference Manual}, for more information
6138 on password encryption, and @ref{Encryption,,, guile, GNU Guile Reference
6139 Manual}, for information on Guile's @code{crypt} procedure.
6144 User group declarations are even simpler:
6147 (user-group (name "students"))
6150 @deftp {Data Type} user-group
6151 This type is for, well, user groups. There are just a few fields:
6157 @item @code{id} (default: @code{#f})
6158 The group identifier (a number). If @code{#f}, a new number is
6159 automatically allocated when the group is created.
6161 @item @code{system?} (default: @code{#f})
6162 This Boolean value indicates whether the group is a ``system'' group.
6163 System groups have low numerical IDs.
6165 @item @code{password} (default: @code{#f})
6166 What, user groups can have a password? Well, apparently yes. Unless
6167 @code{#f}, this field specifies the group's password.
6172 For convenience, a variable lists all the basic user groups one may
6175 @defvr {Scheme Variable} %base-groups
6176 This is the list of basic user groups that users and/or packages expect
6177 to be present on the system. This includes groups such as ``root'',
6178 ``wheel'', and ``users'', as well as groups used to control access to
6179 specific devices such as ``audio'', ``disk'', and ``cdrom''.
6182 @defvr {Scheme Variable} %base-user-accounts
6183 This is the list of basic system accounts that programs may expect to
6184 find on a GNU/Linux system, such as the ``nobody'' account.
6186 Note that the ``root'' account is not included here. It is a
6187 special-case and is automatically added whether or not it is specified.
6194 A @dfn{locale} defines cultural conventions for a particular language
6195 and region of the world (@pxref{Locales,,, libc, The GNU C Library
6196 Reference Manual}). Each locale has a name that typically has the form
6197 @code{@var{language}_@var{territory}.@var{codeset}}---e.g.,
6198 @code{fr_LU.utf8} designates the locale for the French language, with
6199 cultural conventions from Luxembourg, and using the UTF-8 encoding.
6201 @cindex locale definition
6202 Usually, you will want to specify the default locale for the machine
6203 using the @code{locale} field of the @code{operating-system} declaration
6204 (@pxref{operating-system Reference, @code{locale}}).
6206 That locale must be among the @dfn{locale definitions} that are known to
6207 the system---and these are specified in the @code{locale-definitions}
6208 slot of @code{operating-system}. The default value includes locale
6209 definition for some widely used locales, but not for all the available
6210 locales, in order to save space.
6212 If the locale specified in the @code{locale} field is not among the
6213 definitions listed in @code{locale-definitions}, @command{guix system}
6214 raises an error. In that case, you should add the locale definition to
6215 the @code{locale-definitions} field. For instance, to add the North
6216 Frisian locale for Germany, the value of that field may be:
6219 (cons (locale-definition
6220 (name "fy_DE.utf8") (source "fy_DE"))
6221 %default-locale-definitions)
6224 Likewise, to save space, one might want @code{locale-definitions} to
6225 list only the locales that are actually used, as in:
6228 (list (locale-definition
6229 (name "ja_JP.eucjp") (source "ja_JP")
6230 (charset "EUC-JP")))
6234 The compiled locale definitions are available at
6235 @file{/run/current-system/locale/X.Y}, where @code{X.Y} is the libc
6236 version, which is the default location where the GNU@tie{}libc provided
6237 by Guix looks for locale data. This can be overridden using the
6238 @code{LOCPATH} environment variable (@pxref{locales-and-locpath,
6239 @code{LOCPATH} and locale packages}).
6241 The @code{locale-definition} form is provided by the @code{(gnu system
6242 locale)} module. Details are given below.
6244 @deftp {Data Type} locale-definition
6245 This is the data type of a locale definition.
6250 The name of the locale. @xref{Locale Names,,, libc, The GNU C Library
6251 Reference Manual}, for more information on locale names.
6254 The name of the source for that locale. This is typically the
6255 @code{@var{language}_@var{territory}} part of the locale name.
6257 @item @code{charset} (default: @code{"UTF-8"})
6258 The ``character set'' or ``code set'' for that locale,
6259 @uref{http://www.iana.org/assignments/character-sets, as defined by
6265 @defvr {Scheme Variable} %default-locale-definitions
6266 An arbitrary list of commonly used UTF-8 locales, used as the default
6267 value of the @code{locale-definitions} field of @code{operating-system}
6271 @cindex normalized codeset in locale names
6272 These locale definitions use the @dfn{normalized codeset} for the part
6273 that follows the dot in the name (@pxref{Using gettextized software,
6274 normalized codeset,, libc, The GNU C Library Reference Manual}). So for
6275 instance it has @code{uk_UA.utf8} but @emph{not}, say,
6279 @subsubsection Locale Data Compatibility Considerations
6281 @cindex incompatibility, of locale data
6282 @code{operating-system} declarations provide a @code{locale-libcs} field
6283 to specify the GNU@tie{}libc packages that are used to compile locale
6284 declarations (@pxref{operating-system Reference}). ``Why would I
6285 care?'', you may ask. Well, it turns out that the binary format of
6286 locale data is occasionally incompatible from one libc version to
6289 @c See <https://sourceware.org/ml/libc-alpha/2015-09/msg00575.html>
6290 @c and <https://lists.gnu.org/archive/html/guix-devel/2015-08/msg00737.html>.
6291 For instance, a program linked against libc version 2.21 is unable to
6292 read locale data produced with libc 2.22; worse, that program
6293 @emph{aborts} instead of simply ignoring the incompatible locale
6294 data@footnote{Versions 2.23 and later of GNU@tie{}libc will simply skip
6295 the incompatible locale data, which is already an improvement.}.
6296 Similarly, a program linked against libc 2.22 can read most, but not
6297 all, the locale data from libc 2.21 (specifically, @code{LC_COLLATE}
6298 data is incompatible); thus calls to @code{setlocale} may fail, but
6299 programs will not abort.
6301 The ``problem'' in GuixSD is that users have a lot of freedom: They can
6302 choose whether and when to upgrade software in their profiles, and might
6303 be using a libc version different from the one the system administrator
6304 used to build the system-wide locale data.
6306 Fortunately, unprivileged users can also install their own locale data
6307 and define @var{GUIX_LOCPATH} accordingly (@pxref{locales-and-locpath,
6308 @code{GUIX_LOCPATH} and locale packages}).
6310 Still, it is best if the system-wide locale data at
6311 @file{/run/current-system/locale} is built for all the libc versions
6312 actually in use on the system, so that all the programs can access
6313 it---this is especially crucial on a multi-user system. To do that, the
6314 administrator can specify several libc packages in the
6315 @code{locale-libcs} field of @code{operating-system}:
6318 (use-package-modules base)
6322 (locale-libcs (list glibc-2.21 (canonical-package glibc))))
6325 This example would lead to a system containing locale definitions for
6326 both libc 2.21 and the current version of libc in
6327 @file{/run/current-system/locale}.
6331 @subsection Services
6333 @cindex system services
6334 An important part of preparing an @code{operating-system} declaration is
6335 listing @dfn{system services} and their configuration (@pxref{Using the
6336 Configuration System}). System services are typically daemons launched
6337 when the system boots, or other actions needed at that time---e.g.,
6338 configuring network access.
6340 Services are managed by GNU@tie{}dmd (@pxref{Introduction,,, dmd, GNU
6341 dmd Manual}). On a running system, the @command{deco} command allows
6342 you to list the available services, show their status, start and stop
6343 them, or do other specific operations (@pxref{Jump Start,,, dmd, GNU dmd
6344 Manual}). For example:
6350 The above command, run as @code{root}, lists the currently defined
6351 services. The @command{deco doc} command shows a synopsis of the given
6356 Run libc's name service cache daemon (nscd).
6359 The @command{start}, @command{stop}, and @command{restart} sub-commands
6360 have the effect you would expect. For instance, the commands below stop
6361 the nscd service and restart the Xorg display server:
6365 Service nscd has been stopped.
6366 # deco restart xorg-server
6367 Service xorg-server has been stopped.
6368 Service xorg-server has been started.
6371 The following sections document the available services, starting with
6372 the core services, that may be used in an @code{operating-system}
6376 * Base Services:: Essential system services.
6377 * Networking Services:: Network setup, SSH daemon, etc.
6378 * X Window:: Graphical display.
6379 * Desktop Services:: D-Bus and desktop services.
6380 * Database Services:: SQL databases.
6381 * Mail Services:: IMAP, POP3, SMTP, and all that.
6382 * Web Services:: Web servers.
6383 * Various Services:: Other services.
6387 @subsubsection Base Services
6389 The @code{(gnu services base)} module provides definitions for the basic
6390 services that one expects from the system. The services exported by
6391 this module are listed below.
6393 @defvr {Scheme Variable} %base-services
6394 This variable contains a list of basic services (@pxref{Service Types
6395 and Services}, for more information on service objects) one would
6396 expect from the system: a login service (mingetty) on each tty, syslogd,
6397 libc's name service cache daemon (nscd), the udev device manager, and
6400 This is the default value of the @code{services} field of
6401 @code{operating-system} declarations. Usually, when customizing a
6402 system, you will want to append services to @var{%base-services}, like
6406 (cons* (avahi-service) (lsh-service) %base-services)
6410 @deffn {Scheme Procedure} host-name-service @var{name}
6411 Return a service that sets the host name to @var{name}.
6414 @deffn {Scheme Procedure} mingetty-service @var{config}
6415 Return a service to run mingetty according to @var{config}, a
6416 @code{<mingetty-configuration>} object, which specifies the tty to run, among
6420 @deftp {Data Type} mingetty-configuration
6421 This is the data type representing the configuration of Mingetty, which
6422 implements console log-in.
6427 The name of the console this Mingetty runs on---e.g., @code{"tty1"}.
6430 A file-like object containing the ``message of the day''.
6432 @item @code{auto-login} (default: @code{#f})
6433 When true, this field must be a string denoting the user name under
6434 which the the system automatically logs in. When it is @code{#f}, a
6435 user name and password must be entered to log in.
6437 @item @code{login-program} (default: @code{#f})
6438 This must be either @code{#f}, in which case the default log-in program
6439 is used (@command{login} from the Shadow tool suite), or a gexp denoting
6440 the name of the log-in program.
6442 @item @code{login-pause?} (default: @code{#f})
6443 When set to @code{#t} in conjunction with @var{auto-login}, the user
6444 will have to press a key before the log-in shell is launched.
6446 @item @code{mingetty} (default: @var{mingetty})
6447 The Mingetty package to use.
6452 @cindex name service cache daemon
6454 @deffn {Scheme Procedure} nscd-service [@var{config}] [#:glibc glibc] @
6455 [#:name-services '()]
6456 Return a service that runs libc's name service cache daemon (nscd) with the
6457 given @var{config}---an @code{<nscd-configuration>} object. @xref{Name
6458 Service Switch}, for an example.
6461 @defvr {Scheme Variable} %nscd-default-configuration
6462 This is the default @code{<nscd-configuration>} value (see below) used
6463 by @code{nscd-service}. This uses the caches defined by
6464 @var{%nscd-default-caches}; see below.
6467 @deftp {Data Type} nscd-configuration
6468 This is the type representing the name service cache daemon (nscd)
6473 @item @code{name-services} (default: @code{'()})
6474 List of packages denoting @dfn{name services} that must be visible to
6475 the nscd---e.g., @code{(list @var{nss-mdns})}.
6477 @item @code{glibc} (default: @var{glibc})
6478 Package object denoting the GNU C Library providing the @command{nscd}
6481 @item @code{log-file} (default: @code{"/var/log/nscd.log"})
6482 Name of nscd's log file. This is where debugging output goes when
6483 @code{debug-level} is strictly positive.
6485 @item @code{debug-level} (default: @code{0})
6486 Integer denoting the debugging levels. Higher numbers mean more
6487 debugging output is logged.
6489 @item @code{caches} (default: @var{%nscd-default-caches})
6490 List of @code{<nscd-cache>} objects denoting things to be cached; see
6496 @deftp {Data Type} nscd-cache
6497 Data type representing a cache database of nscd and its parameters.
6501 @item @code{database}
6502 This is a symbol representing the name of the database to be cached.
6503 Valid values are @code{passwd}, @code{group}, @code{hosts}, and
6504 @code{services}, which designate the corresponding NSS database
6505 (@pxref{NSS Basics,,, libc, The GNU C Library Reference Manual}).
6507 @item @code{positive-time-to-live}
6508 @itemx @code{negative-time-to-live} (default: @code{20})
6509 A number representing the number of seconds during which a positive or
6510 negative lookup result remains in cache.
6512 @item @code{check-files?} (default: @code{#t})
6513 Whether to check for updates of the files corresponding to
6516 For instance, when @var{database} is @code{hosts}, setting this flag
6517 instructs nscd to check for updates in @file{/etc/hosts} and to take
6520 @item @code{persistent?} (default: @code{#t})
6521 Whether the cache should be stored persistently on disk.
6523 @item @code{shared?} (default: @code{#t})
6524 Whether the cache should be shared among users.
6526 @item @code{max-database-size} (default: 32@tie{}MiB)
6527 Maximum size in bytes of the database cache.
6529 @c XXX: 'suggested-size' and 'auto-propagate?' seem to be expert
6530 @c settings, so leave them out.
6535 @defvr {Scheme Variable} %nscd-default-caches
6536 List of @code{<nscd-cache>} objects used by default by
6537 @code{nscd-configuration} (see above.)
6539 It enables persistent and aggressive caching of service and host name
6540 lookups. The latter provides better host name lookup performance,
6541 resilience in the face of unreliable name servers, and also better
6542 privacy---often the result of host name lookups is in local cache, so
6543 external name servers do not even need to be queried.
6547 @deffn {Scheme Procedure} syslog-service [#:config-file #f]
6548 Return a service that runs @code{syslogd}. If configuration file name
6549 @var{config-file} is not specified, use some reasonable default
6553 @anchor{guix-configuration-type}
6554 @deftp {Data Type} guix-configuration
6555 This data type represents the configuration of the Guix build daemon.
6556 @xref{Invoking guix-daemon}, for more information.
6559 @item @code{guix} (default: @var{guix})
6560 The Guix package to use.
6562 @item @code{build-group} (default: @code{"guixbuild"})
6563 Name of the group for build user accounts.
6565 @item @code{build-accounts} (default: @code{10})
6566 Number of build user accounts to create.
6568 @item @code{authorize-key?} (default: @code{#t})
6569 Whether to authorize the substitute key for @code{hydra.gnu.org}
6570 (@pxref{Substitutes}).
6572 @item @code{use-substitutes?} (default: @code{#t})
6573 Whether to use substitutes.
6575 @item @code{substitute-urls} (default: @var{%default-substitute-urls})
6576 The list of URLs where to look for substitutes by default.
6578 @item @code{extra-options} (default: @code{'()})
6579 List of extra command-line options for @command{guix-daemon}.
6581 @item @code{lsof} (default: @var{lsof})
6582 @itemx @code{lsh} (default: @var{lsh})
6583 The lsof and lsh packages to use.
6588 @deffn {Scheme Procedure} guix-service @var{config}
6589 Return a service that runs the Guix build daemon according to
6593 @deffn {Scheme Procedure} udev-service [#:udev udev]
6594 Run @var{udev}, which populates the @file{/dev} directory dynamically.
6597 @deffn {Scheme Procedure} console-keymap-service @var{file}
6598 Return a service to load console keymap from @var{file} using
6599 @command{loadkeys} command.
6602 @deffn {Scheme Procedure} gpm-service-type [#:gpm @var{gpm}] @
6604 Run @var{gpm}, the general-purpose mouse daemon, with the given
6605 command-line @var{options}. GPM allows users to use the mouse in the console,
6606 notably to select, copy, and paste text. The default value of @var{options}
6607 uses the @code{ps2} protocol, which works for both USB and PS/2 mice.
6609 This service is not part of @var{%base-services}.
6612 @anchor{guix-publish-service}
6613 @deffn {Scheme Procedure} guix-publish-service [#:guix @var{guix}] @
6614 [#:port 80] [#:host "localhost"]
6615 Return a service that runs @command{guix publish} listening on @var{host}
6616 and @var{port} (@pxref{Invoking guix publish}).
6618 This assumes that @file{/etc/guix} already contains a signing key pair as
6619 created by @command{guix archive --generate-key} (@pxref{Invoking guix
6620 archive}). If that is not the case, the service will fail to start.
6624 @node Networking Services
6625 @subsubsection Networking Services
6627 The @code{(gnu services networking)} module provides services to configure
6628 the network interface.
6630 @cindex DHCP, networking service
6631 @deffn {Scheme Procedure} dhcp-client-service [#:dhcp @var{isc-dhcp}]
6632 Return a service that runs @var{dhcp}, a Dynamic Host Configuration
6633 Protocol (DHCP) client, on all the non-loopback network interfaces.
6636 @deffn {Scheme Procedure} static-networking-service @var{interface} @var{ip} @
6637 [#:gateway #f] [#:name-services @code{'()}]
6638 Return a service that starts @var{interface} with address @var{ip}. If
6639 @var{gateway} is true, it must be a string specifying the default network
6644 @cindex network management
6645 @deffn {Scheme Procedure} wicd-service [#:wicd @var{wicd}]
6646 Return a service that runs @url{https://launchpad.net/wicd,Wicd}, a network
6647 management daemon that aims to simplify wired and wireless networking.
6649 This service adds the @var{wicd} package to the global profile, providing
6650 several commands to interact with the daemon and configure networking:
6651 @command{wicd-client}, a graphical user interface, and the @command{wicd-cli}
6652 and @command{wicd-curses} user interfaces.
6655 @deffn {Scheme Procedure} ntp-service [#:ntp @var{ntp}] @
6656 [#:name-service @var{%ntp-servers}]
6657 Return a service that runs the daemon from @var{ntp}, the
6658 @uref{http://www.ntp.org, Network Time Protocol package}. The daemon will
6659 keep the system clock synchronized with that of @var{servers}.
6662 @defvr {Scheme Variable} %ntp-servers
6663 List of host names used as the default NTP servers.
6666 @deffn {Scheme Procedure} tor-service [@var{config-file}] [#:tor @var{tor}]
6667 Return a service to run the @uref{https://torproject.org, Tor} anonymous
6670 The daemon runs as the @code{tor} unprivileged user. It is passed
6671 @var{config-file}, a file-like object, with an additional @code{User tor} line
6672 and lines for hidden services added via @code{tor-hidden-service}. Run
6673 @command{man tor} for information about the configuration file.
6676 @deffn {Scheme Procedure} tor-hidden-service @var{name} @var{mapping}
6677 Define a new Tor @dfn{hidden service} called @var{name} and implementing
6678 @var{mapping}. @var{mapping} is a list of port/host tuples, such as:
6681 '((22 \"127.0.0.1:22\")
6682 (80 \"127.0.0.1:8080\"))
6685 In this example, port 22 of the hidden service is mapped to local port 22, and
6686 port 80 is mapped to local port 8080.
6688 This creates a @file{/var/lib/tor/hidden-services/@var{name}} directory, where
6689 the @file{hostname} file contains the @code{.onion} host name for the hidden
6692 See @uref{https://www.torproject.org/docs/tor-hidden-service.html.en, the Tor
6693 project's documentation} for more information.
6696 @deffn {Scheme Procedure} bitlbee-service [#:bitlbee bitlbee] @
6697 [#:interface "127.0.0.1"] [#:port 6667] @
6698 [#:extra-settings ""]
6699 Return a service that runs @url{http://bitlbee.org,BitlBee}, a daemon that
6700 acts as a gateway between IRC and chat networks.
6702 The daemon will listen to the interface corresponding to the IP address
6703 specified in @var{interface}, on @var{port}. @code{127.0.0.1} means that only
6704 local clients can connect, whereas @code{0.0.0.0} means that connections can
6705 come from any networking interface.
6707 In addition, @var{extra-settings} specifies a string to append to the
6711 Furthermore, @code{(gnu services ssh)} provides the following service.
6713 @deffn {Scheme Procedure} lsh-service [#:host-key "/etc/lsh/host-key"] @
6714 [#:daemonic? #t] [#:interfaces '()] [#:port-number 22] @
6715 [#:allow-empty-passwords? #f] [#:root-login? #f] @
6716 [#:syslog-output? #t] [#:x11-forwarding? #t] @
6717 [#:tcp/ip-forwarding? #t] [#:password-authentication? #t] @
6718 [#:public-key-authentication? #t] [#:initialize? #t]
6719 Run the @command{lshd} program from @var{lsh} to listen on port @var{port-number}.
6720 @var{host-key} must designate a file containing the host key, and readable
6723 When @var{daemonic?} is true, @command{lshd} will detach from the
6724 controlling terminal and log its output to syslogd, unless one sets
6725 @var{syslog-output?} to false. Obviously, it also makes lsh-service
6726 depend on existence of syslogd service. When @var{pid-file?} is true,
6727 @command{lshd} writes its PID to the file called @var{pid-file}.
6729 When @var{initialize?} is true, automatically create the seed and host key
6730 upon service activation if they do not exist yet. This may take long and
6731 require interaction.
6733 When @var{initialize?} is false, it is up to the user to initialize the
6734 randomness generator (@pxref{lsh-make-seed,,, lsh, LSH Manual}), and to create
6735 a key pair with the private key stored in file @var{host-key} (@pxref{lshd
6736 basics,,, lsh, LSH Manual}).
6738 When @var{interfaces} is empty, lshd listens for connections on all the
6739 network interfaces; otherwise, @var{interfaces} must be a list of host names
6742 @var{allow-empty-passwords?} specifies whether to accept log-ins with empty
6743 passwords, and @var{root-login?} specifies whether to accept log-ins as
6746 The other options should be self-descriptive.
6749 @defvr {Scheme Variable} %facebook-host-aliases
6750 This variable contains a string for use in @file{/etc/hosts}
6751 (@pxref{Host Names,,, libc, The GNU C Library Reference Manual}). Each
6752 line contains a entry that maps a known server name of the Facebook
6753 on-line service---e.g., @code{www.facebook.com}---to the local
6754 host---@code{127.0.0.1} or its IPv6 equivalent, @code{::1}.
6756 This variable is typically used in the @code{hosts-file} field of an
6757 @code{operating-system} declaration (@pxref{operating-system Reference,
6758 @file{/etc/hosts}}):
6761 (use-modules (gnu) (guix))
6764 (host-name "mymachine")
6767 ;; Create a /etc/hosts file with aliases for "localhost"
6768 ;; and "mymachine", as well as for Facebook servers.
6770 (string-append (local-host-aliases host-name)
6771 %facebook-host-aliases))))
6774 This mechanism can prevent programs running locally, such as Web
6775 browsers, from accessing Facebook.
6778 The @code{(gnu services avahi)} provides the following definition.
6780 @deffn {Scheme Procedure} avahi-service [#:avahi @var{avahi}] @
6781 [#:host-name #f] [#:publish? #t] [#:ipv4? #t] @
6782 [#:ipv6? #t] [#:wide-area? #f] @
6783 [#:domains-to-browse '()]
6784 Return a service that runs @command{avahi-daemon}, a system-wide
6785 mDNS/DNS-SD responder that allows for service discovery and
6786 "zero-configuration" host name lookups (see @uref{http://avahi.org/}), and
6787 extends the name service cache daemon (nscd) so that it can resolve
6788 @code{.local} host names using
6789 @uref{http://0pointer.de/lennart/projects/nss-mdns/, nss-mdns}. Additionally,
6790 add the @var{avahi} package to the system profile so that commands such as
6791 @command{avahi-browse} are directly usable.
6793 If @var{host-name} is different from @code{#f}, use that as the host name to
6794 publish for this machine; otherwise, use the machine's actual host name.
6796 When @var{publish?} is true, publishing of host names and services is allowed;
6797 in particular, avahi-daemon will publish the machine's host name and IP
6798 address via mDNS on the local network.
6800 When @var{wide-area?} is true, DNS-SD over unicast DNS is enabled.
6802 Boolean values @var{ipv4?} and @var{ipv6?} determine whether to use IPv4/IPv6
6808 @subsubsection X Window
6810 Support for the X Window graphical display system---specifically
6811 Xorg---is provided by the @code{(gnu services xorg)} module. Note that
6812 there is no @code{xorg-service} procedure. Instead, the X server is
6813 started by the @dfn{login manager}, currently SLiM.
6815 @deffn {Scheme Procedure} slim-service [#:allow-empty-passwords? #f] @
6816 [#:auto-login? #f] [#:default-user ""] [#:startx] @
6817 [#:theme @var{%default-slim-theme}] @
6818 [#:theme-name @var{%default-slim-theme-name}]
6819 Return a service that spawns the SLiM graphical login manager, which in
6820 turn starts the X display server with @var{startx}, a command as returned by
6821 @code{xorg-start-command}.
6825 SLiM automatically looks for session types described by the @file{.desktop}
6826 files in @file{/run/current-system/profile/share/xsessions} and allows users
6827 to choose a session from the log-in screen using @kbd{F1}. Packages such as
6828 @var{xfce}, @var{sawfish}, and @var{ratpoison} provide @file{.desktop} files;
6829 adding them to the system-wide set of packages automatically makes them
6830 available at the log-in screen.
6832 In addition, @file{~/.xsession} files are honored. When available,
6833 @file{~/.xsession} must be an executable that starts a window manager
6834 and/or other X clients.
6836 When @var{allow-empty-passwords?} is true, allow logins with an empty
6837 password. When @var{auto-login?} is true, log in automatically as
6840 If @var{theme} is @code{#f}, the use the default log-in theme; otherwise
6841 @var{theme} must be a gexp denoting the name of a directory containing the
6842 theme to use. In that case, @var{theme-name} specifies the name of the
6846 @defvr {Scheme Variable} %default-theme
6847 @defvrx {Scheme Variable} %default-theme-name
6848 The G-Expression denoting the default SLiM theme and its name.
6851 @deffn {Scheme Procedure} xorg-start-command [#:guile] @
6852 [#:configuration-file #f] [#:xorg-server @var{xorg-server}]
6853 Return a derivation that builds a @var{guile} script to start the X server
6854 from @var{xorg-server}. @var{configuration-file} is the server configuration
6855 file or a derivation that builds it; when omitted, the result of
6856 @code{xorg-configuration-file} is used.
6858 Usually the X server is started by a login manager.
6861 @deffn {Scheme Procedure} xorg-configuration-file @
6862 [#:drivers '()] [#:resolutions '()] [#:extra-config '()]
6863 Return a configuration file for the Xorg server containing search paths for
6864 all the common drivers.
6866 @var{drivers} must be either the empty list, in which case Xorg chooses a
6867 graphics driver automatically, or a list of driver names that will be tried in
6868 this order---e.g., @code{(\"modesetting\" \"vesa\")}.
6870 Likewise, when @var{resolutions} is the empty list, Xorg chooses an
6871 appropriate screen resolution; otherwise, it must be a list of
6872 resolutions---e.g., @code{((1024 768) (640 480))}.
6874 Last, @var{extra-config} is a list of strings or objects appended to the
6875 @code{text-file*} argument list. It is used to pass extra text to be added
6876 verbatim to the configuration file.
6879 @deffn {Scheme Procedure} screen-locker-service @var{package} [@var{name}]
6880 Add @var{package}, a package for a screen-locker or screen-saver whose
6881 command is @var{program}, to the set of setuid programs and add a PAM entry
6882 for it. For example:
6885 (screen-locker-service xlockmore "xlock")
6888 makes the good ol' XlockMore usable.
6892 @node Desktop Services
6893 @subsubsection Desktop Services
6895 The @code{(gnu services desktop)} module provides services that are
6896 usually useful in the context of a ``desktop'' setup---that is, on a
6897 machine running a graphical display server, possibly with graphical user
6900 To simplify things, the module defines a variable containing the set of
6901 services that users typically expect on a machine with a graphical
6902 environment and networking:
6904 @defvr {Scheme Variable} %desktop-services
6905 This is a list of services that builds upon @var{%base-services} and
6906 adds or adjust services for a typical ``desktop'' setup.
6908 In particular, it adds a graphical login manager (@pxref{X Window,
6909 @code{slim-service}}), screen lockers,
6910 a network management tool (@pxref{Networking
6911 Services, @code{wicd-service}}), energy and color management services,
6912 the @code{elogind} login and seat manager, the Polkit privilege service,
6913 the GeoClue location service, an NTP client (@pxref{Networking
6914 Services}), the Avahi daemon, and has the name service switch service
6915 configured to be able to use @code{nss-mdns} (@pxref{Name Service
6919 The @var{%desktop-services} variable can be used as the @code{services}
6920 field of an @code{operating-system} declaration (@pxref{operating-system
6921 Reference, @code{services}}).
6923 The actual service definitions provided by @code{(gnu services dbus)}
6924 and @code{(gnu services desktop)} are described below.
6926 @deffn {Scheme Procedure} dbus-service [#:dbus @var{dbus}] [#:services '()]
6927 Return a service that runs the ``system bus'', using @var{dbus}, with
6928 support for @var{services}.
6930 @uref{http://dbus.freedesktop.org/, D-Bus} is an inter-process communication
6931 facility. Its system bus is used to allow system services to communicate
6932 and be notified of system-wide events.
6934 @var{services} must be a list of packages that provide an
6935 @file{etc/dbus-1/system.d} directory containing additional D-Bus configuration
6936 and policy files. For example, to allow avahi-daemon to use the system bus,
6937 @var{services} must be equal to @code{(list avahi)}.
6940 @deffn {Scheme Procedure} elogind-service [#:config @var{config}]
6941 Return a service that runs the @code{elogind} login and
6942 seat management daemon. @uref{https://github.com/andywingo/elogind,
6943 Elogind} exposes a D-Bus interface that can be used to know which users
6944 are logged in, know what kind of sessions they have open, suspend the
6945 system, inhibit system suspend, reboot the system, and other tasks.
6947 Elogind handles most system-level power events for a computer, for
6948 example suspending the system when a lid is closed, or shutting it down
6949 when the power button is pressed.
6951 The @var{config} keyword argument specifies the configuration for
6952 elogind, and should be the result of a @code{(elogind-configuration
6953 (@var{parameter} @var{value})...)} invocation. Available parameters and
6954 their default values are:
6957 @item kill-user-processes?
6959 @item kill-only-users
6961 @item kill-exclude-users
6963 @item inhibit-delay-max-seconds
6965 @item handle-power-key
6967 @item handle-suspend-key
6969 @item handle-hibernate-key
6971 @item handle-lid-switch
6973 @item handle-lid-switch-docked
6975 @item power-key-ignore-inhibited?
6977 @item suspend-key-ignore-inhibited?
6979 @item hibernate-key-ignore-inhibited?
6981 @item lid-switch-ignore-inhibited?
6983 @item holdoff-timeout-seconds
6987 @item idle-action-seconds
6989 @item runtime-directory-size-percent
6991 @item runtime-directory-size
6996 @code{("mem" "standby" "freeze")}
6999 @item hibernate-state
7001 @item hibernate-mode
7002 @code{("platform" "shutdown")}
7003 @item hybrid-sleep-state
7005 @item hybrid-sleep-mode
7006 @code{("suspend" "platform" "shutdown")}
7010 @deffn {Scheme Procedure} polkit-service @
7011 [#:polkit @var{polkit}]
7012 Return a service that runs the
7013 @uref{http://www.freedesktop.org/wiki/Software/polkit/, Polkit privilege
7014 management service}, which allows system administrators to grant access to
7015 privileged operations in a structured way. By querying the Polkit service, a
7016 privileged system component can know when it should grant additional
7017 capabilities to ordinary users. For example, an ordinary user can be granted
7018 the capability to suspend the system if the user is logged in locally.
7021 @deffn {Scheme Procedure} upower-service [#:upower @var{upower}] @
7022 [#:watts-up-pro? #f] @
7023 [#:poll-batteries? #t] @
7024 [#:ignore-lid? #f] @
7025 [#:use-percentage-for-policy? #f] @
7026 [#:percentage-low 10] @
7027 [#:percentage-critical 3] @
7028 [#:percentage-action 2] @
7030 [#:time-critical 300] @
7031 [#:time-action 120] @
7032 [#:critical-power-action 'hybrid-sleep]
7033 Return a service that runs @uref{http://upower.freedesktop.org/,
7034 @command{upowerd}}, a system-wide monitor for power consumption and battery
7035 levels, with the given configuration settings. It implements the
7036 @code{org.freedesktop.UPower} D-Bus interface, and is notably used by
7040 @deffn {Scheme Procedure} udisks-service [#:udisks @var{udisks}]
7041 Return a service for @uref{http://udisks.freedesktop.org/docs/latest/,
7042 UDisks}, a @dfn{disk management} daemon that provides user interfaces with
7043 notifications and ways to mount/unmount disks. Programs that talk to UDisks
7044 include the @command{udisksctl} command, part of UDisks, and GNOME Disks.
7047 @deffn {Scheme Procedure} colord-service [#:colord @var{colord}]
7048 Return a service that runs @command{colord}, a system service with a D-Bus
7049 interface to manage the color profiles of input and output devices such as
7050 screens and scanners. It is notably used by the GNOME Color Manager graphical
7051 tool. See @uref{http://www.freedesktop.org/software/colord/, the colord web
7052 site} for more information.
7055 @deffn {Scheme Procedure} geoclue-application name [#:allowed? #t] [#:system? #f] [#:users '()]
7056 Return an configuration allowing an application to access GeoClue
7057 location data. @var{name} is the Desktop ID of the application, without
7058 the @code{.desktop} part. If @var{allowed?} is true, the application
7059 will have access to location information by default. The boolean
7060 @var{system?} value indicates that an application is a system component
7061 or not. Finally @var{users} is a list of UIDs of all users for which
7062 this application is allowed location info access. An empty users list
7063 means that all users are allowed.
7066 @defvr {Scheme Variable} %standard-geoclue-applications
7067 The standard list of well-known GeoClue application configurations,
7068 granting authority to GNOME's date-and-time utility to ask for the
7069 current location in order to set the time zone, and allowing the Firefox
7070 (IceCat) and Epiphany web browsers to request location information.
7071 Firefox and Epiphany both query the user before allowing a web page to
7072 know the user's location.
7075 @deffn {Scheme Procedure} geoclue-service [#:colord @var{colord}] @
7077 [#:wifi-geolocation-url "https://location.services.mozilla.com/v1/geolocate?key=geoclue"] @
7079 [#:wifi-submission-url "https://location.services.mozilla.com/v1/submit?key=geoclue"] @
7080 [#:submission-nick "geoclue"] @
7081 [#:applications %standard-geoclue-applications]
7082 Return a service that runs the GeoClue location service. This service
7083 provides a D-Bus interface to allow applications to request access to a
7084 user's physical location, and optionally to add information to online
7085 location databases. See
7086 @uref{https://wiki.freedesktop.org/www/Software/GeoClue/, the GeoClue
7087 web site} for more information.
7090 @node Database Services
7091 @subsubsection Database Services
7093 The @code{(gnu services databases)} module provides the following service.
7095 @deffn {Scheme Procedure} postgresql-service [#:postgresql postgresql] @
7096 [#:config-file] [#:data-directory ``/var/lib/postgresql/data'']
7097 Return a service that runs @var{postgresql}, the PostgreSQL database
7100 The PostgreSQL daemon loads its runtime configuration from
7101 @var{config-file} and stores the database cluster in
7102 @var{data-directory}.
7106 @subsubsection Mail Services
7108 The @code{(gnu services mail)} module provides Guix service definitions
7109 for mail services. Currently the only implemented service is Dovecot,
7110 an IMAP, POP3, and LMTP server.
7112 Guix does not yet have a mail transfer agent (MTA), although for some
7113 lightweight purposes the @code{esmtp} relay-only MTA may suffice. Help
7114 is needed to properly integrate a full MTA, such as Postfix. Patches
7117 To add an IMAP/POP3 server to a GuixSD system, add a
7118 @code{dovecot-service} to the operating system definition:
7120 @deffn {Scheme Procedure} dovecot-service [#:config (dovecot-configuration)]
7121 Return a service that runs the Dovecot IMAP/POP3/LMTP mail server.
7124 By default, Dovecot doesn't need much configuration; the default
7125 configuration object created by @code{(dovecot-configuration)} will
7126 suffice if your mail is delivered to @code{~/Maildir}. A self-signed
7127 certificate will be generated for TLS-protected connections, though
7128 Dovecot will also listen on cleartext ports by default. There are a
7129 number of options though which mail administrators might need to change,
7130 and as is the case with other services, Guix allows the system
7131 administrator to specify these parameters via a uniform Scheme interface.
7133 For example, to specify that mail is located at @code{maildir~/.mail},
7134 one would instantiate the Dovecot service like this:
7137 (dovecot-service #:config
7138 (dovecot-configuration
7139 (mail-location "maildir:~/.mail")))
7142 The available configuration parameters follow. Each parameter
7143 definition is preceded by its type; for example, @samp{string-list foo}
7144 indicates that the @code{foo} parameter should be specified as a list of
7145 strings. There is also a way to specify the configuration as a string,
7146 if you have an old @code{dovecot.conf} file that you want to port over
7147 from some other system; see the end for more details.
7149 @c The following documentation was initially generated by
7150 @c (generate-documentation) in (gnu services mail). Manually maintained
7151 @c documentation is better, so we shouldn't hesitate to edit below as
7152 @c needed. However if the change you want to make to this documentation
7153 @c can be done in an automated way, it's probably easier to change
7154 @c (generate-documentation) than to make it below and have to deal with
7155 @c the churn as dovecot updates.
7157 Available @code{dovecot-configuration} fields are:
7159 @deftypevr {@code{dovecot-configuration} parameter} package dovecot
7160 The dovecot package.
7163 @deftypevr {@code{dovecot-configuration} parameter} comma-separated-string-list listen
7164 A list of IPs or hosts where to listen in for connections. @samp{*}
7165 listens in all IPv4 interfaces, @samp{::} listens in all IPv6
7166 interfaces. If you want to specify non-default ports or anything more
7167 complex, customize the address and port fields of the
7168 @samp{inet-listener} of the specific services you are interested in.
7171 @deftypevr {@code{dovecot-configuration} parameter} protocol-configuration-list protocols
7172 List of protocols we want to serve. Available protocols include
7173 @samp{imap}, @samp{pop3}, and @samp{lmtp}.
7175 Available @code{protocol-configuration} fields are:
7177 @deftypevr {@code{protocol-configuration} parameter} string name
7178 The name of the protocol.
7181 @deftypevr {@code{protocol-configuration} parameter} string auth-socket-path
7182 UNIX socket path to master authentication server to find users.
7183 This is used by imap (for shared users) and lda.
7184 Defaults to @samp{"/var/run/dovecot/auth-userdb"}.
7187 @deftypevr {@code{protocol-configuration} parameter} space-separated-string-list mail-plugins
7188 Space separated list of plugins to load.
7191 @deftypevr {@code{protocol-configuration} parameter} non-negative-integer mail-max-userip-connections
7192 Maximum number of IMAP connections allowed for a user from each IP
7193 address. NOTE: The username is compared case-sensitively.
7194 Defaults to @samp{10}.
7199 @deftypevr {@code{dovecot-configuration} parameter} service-configuration-list services
7200 List of services to enable. Available services include @samp{imap},
7201 @samp{imap-login}, @samp{pop3}, @samp{pop3-login}, @samp{auth}, and
7204 Available @code{service-configuration} fields are:
7206 @deftypevr {@code{service-configuration} parameter} string kind
7207 The service kind. Valid values include @code{director},
7208 @code{imap-login}, @code{pop3-login}, @code{lmtp}, @code{imap},
7209 @code{pop3}, @code{auth}, @code{auth-worker}, @code{dict},
7210 @code{tcpwrap}, @code{quota-warning}, or anything else.
7213 @deftypevr {@code{service-configuration} parameter} listener-configuration-list listeners
7214 Listeners for the service. A listener is either an
7215 @code{unix-listener-configuration}, a @code{fifo-listener-configuration}, or
7216 an @code{inet-listener-configuration}.
7217 Defaults to @samp{()}.
7219 Available @code{unix-listener-configuration} fields are:
7221 @deftypevr {@code{unix-listener-configuration} parameter} file-name path
7222 The file name on which to listen.
7225 @deftypevr {@code{unix-listener-configuration} parameter} string mode
7226 The access mode for the socket.
7227 Defaults to @samp{"0600"}.
7230 @deftypevr {@code{unix-listener-configuration} parameter} string user
7231 The user to own the the socket.
7232 Defaults to @samp{""}.
7235 @deftypevr {@code{unix-listener-configuration} parameter} string group
7236 The group to own the socket.
7237 Defaults to @samp{""}.
7241 Available @code{fifo-listener-configuration} fields are:
7243 @deftypevr {@code{fifo-listener-configuration} parameter} file-name path
7244 The file name on which to listen.
7247 @deftypevr {@code{fifo-listener-configuration} parameter} string mode
7248 The access mode for the socket.
7249 Defaults to @samp{"0600"}.
7252 @deftypevr {@code{fifo-listener-configuration} parameter} string user
7253 The user to own the the socket.
7254 Defaults to @samp{""}.
7257 @deftypevr {@code{fifo-listener-configuration} parameter} string group
7258 The group to own the socket.
7259 Defaults to @samp{""}.
7263 Available @code{inet-listener-configuration} fields are:
7265 @deftypevr {@code{inet-listener-configuration} parameter} string protocol
7266 The protocol to listen for.
7269 @deftypevr {@code{inet-listener-configuration} parameter} string address
7270 The address on which to listen, or empty for all addresses.
7271 Defaults to @samp{""}.
7274 @deftypevr {@code{inet-listener-configuration} parameter} non-negative-integer port
7275 The port on which to listen.
7278 @deftypevr {@code{inet-listener-configuration} parameter} boolean ssl?
7279 Whether to use SSL for this service; @samp{yes}, @samp{no}, or
7281 Defaults to @samp{#t}.
7286 @deftypevr {@code{service-configuration} parameter} non-negative-integer service-count
7287 Number of connections to handle before starting a new process.
7288 Typically the only useful values are 0 (unlimited) or 1. 1 is more
7289 secure, but 0 is faster. <doc/wiki/LoginProcess.txt>.
7290 Defaults to @samp{1}.
7293 @deftypevr {@code{service-configuration} parameter} non-negative-integer process-min-avail
7294 Number of processes to always keep waiting for more connections.
7295 Defaults to @samp{0}.
7298 @deftypevr {@code{service-configuration} parameter} non-negative-integer vsz-limit
7299 If you set @samp{service-count 0}, you probably need to grow
7301 Defaults to @samp{256000000}.
7306 @deftypevr {@code{dovecot-configuration} parameter} dict-configuration dict
7307 Dict configuration, as created by the @code{dict-configuration}
7310 Available @code{dict-configuration} fields are:
7312 @deftypevr {@code{dict-configuration} parameter} free-form-fields entries
7313 A list of key-value pairs that this dict should hold.
7314 Defaults to @samp{()}.
7319 @deftypevr {@code{dovecot-configuration} parameter} passdb-configuration-list passdbs
7320 List of passdb configurations, each one created by the
7321 @code{passdb-configuration} constructor.
7323 Available @code{passdb-configuration} fields are:
7325 @deftypevr {@code{passdb-configuration} parameter} string driver
7326 The driver that the passdb should use. Valid values include
7327 @samp{pam}, @samp{passwd}, @samp{shadow}, @samp{bsdauth}, and
7329 Defaults to @samp{"pam"}.
7332 @deftypevr {@code{passdb-configuration} parameter} free-form-args args
7333 A list of key-value args to the passdb driver.
7334 Defaults to @samp{()}.
7339 @deftypevr {@code{dovecot-configuration} parameter} userdb-configuration-list userdbs
7340 List of userdb configurations, each one created by the
7341 @code{userdb-configuration} constructor.
7343 Available @code{userdb-configuration} fields are:
7345 @deftypevr {@code{userdb-configuration} parameter} string driver
7346 The driver that the userdb should use. Valid values include
7347 @samp{passwd} and @samp{static}.
7348 Defaults to @samp{"passwd"}.
7351 @deftypevr {@code{userdb-configuration} parameter} free-form-args args
7352 A list of key-value args to the userdb driver.
7353 Defaults to @samp{()}.
7356 @deftypevr {@code{userdb-configuration} parameter} free-form-args override-fields
7357 Override fields from passwd.
7358 Defaults to @samp{()}.
7363 @deftypevr {@code{dovecot-configuration} parameter} plugin-configuration plugin-configuration
7364 Plug-in configuration, created by the @code{plugin-configuration}
7368 @deftypevr {@code{dovecot-configuration} parameter} list-of-namespace-configuration namespaces
7369 List of namespaces. Each item in the list is created by the
7370 @code{namespace-configuration} constructor.
7372 Available @code{namespace-configuration} fields are:
7374 @deftypevr {@code{namespace-configuration} parameter} string name
7375 Name for this namespace.
7378 @deftypevr {@code{namespace-configuration} parameter} string type
7379 Namespace type: @samp{private}, @samp{shared} or @samp{public}.
7380 Defaults to @samp{"private"}.
7383 @deftypevr {@code{namespace-configuration} parameter} string separator
7384 Hierarchy separator to use. You should use the same separator for
7385 all namespaces or some clients get confused. @samp{/} is usually a good
7386 one. The default however depends on the underlying mail storage
7388 Defaults to @samp{""}.
7391 @deftypevr {@code{namespace-configuration} parameter} string prefix
7392 Prefix required to access this namespace. This needs to be
7393 different for all namespaces. For example @samp{Public/}.
7394 Defaults to @samp{""}.
7397 @deftypevr {@code{namespace-configuration} parameter} string location
7398 Physical location of the mailbox. This is in same format as
7399 mail_location, which is also the default for it.
7400 Defaults to @samp{""}.
7403 @deftypevr {@code{namespace-configuration} parameter} boolean inbox?
7404 There can be only one INBOX, and this setting defines which
7406 Defaults to @samp{#f}.
7409 @deftypevr {@code{namespace-configuration} parameter} boolean hidden?
7410 If namespace is hidden, it's not advertised to clients via NAMESPACE
7411 extension. You'll most likely also want to set @samp{list? #f}. This is mostly
7412 useful when converting from another server with different namespaces
7413 which you want to deprecate but still keep working. For example you can
7414 create hidden namespaces with prefixes @samp{~/mail/}, @samp{~%u/mail/}
7416 Defaults to @samp{#f}.
7419 @deftypevr {@code{namespace-configuration} parameter} boolean list?
7420 Show the mailboxes under this namespace with LIST command. This
7421 makes the namespace visible for clients that don't support NAMESPACE
7422 extension. The special @code{children} value lists child mailboxes, but
7423 hides the namespace prefix.
7424 Defaults to @samp{#t}.
7427 @deftypevr {@code{namespace-configuration} parameter} boolean subscriptions?
7428 Namespace handles its own subscriptions. If set to @code{#f}, the
7429 parent namespace handles them. The empty prefix should always have this
7431 Defaults to @samp{#t}.
7434 @deftypevr {@code{namespace-configuration} parameter} mailbox-configuration-list mailboxes
7435 List of predefined mailboxes in this namespace.
7436 Defaults to @samp{()}.
7438 Available @code{mailbox-configuration} fields are:
7440 @deftypevr {@code{mailbox-configuration} parameter} string name
7441 Name for this mailbox.
7444 @deftypevr {@code{mailbox-configuration} parameter} string auto
7445 @samp{create} will automatically create this mailbox.
7446 @samp{subscribe} will both create and subscribe to the mailbox.
7447 Defaults to @samp{"no"}.
7450 @deftypevr {@code{mailbox-configuration} parameter} space-separated-string-list special-use
7451 List of IMAP @code{SPECIAL-USE} attributes as specified by RFC 6154.
7452 Valid values are @code{\All}, @code{\Archive}, @code{\Drafts},
7453 @code{\Flagged}, @code{\Junk}, @code{\Sent}, and @code{\Trash}.
7454 Defaults to @samp{()}.
7461 @deftypevr {@code{dovecot-configuration} parameter} file-name base-dir
7462 Base directory where to store runtime data.
7463 Defaults to @samp{"/var/run/dovecot/"}.
7466 @deftypevr {@code{dovecot-configuration} parameter} string login-greeting
7467 Greeting message for clients.
7468 Defaults to @samp{"Dovecot ready."}.
7471 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-trusted-networks
7472 List of trusted network ranges. Connections from these IPs are
7473 allowed to override their IP addresses and ports (for logging and for
7474 authentication checks). @samp{disable-plaintext-auth} is also ignored
7475 for these networks. Typically you'd specify your IMAP proxy servers
7477 Defaults to @samp{()}.
7480 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-access-sockets
7481 List of login access check sockets (e.g. tcpwrap).
7482 Defaults to @samp{()}.
7485 @deftypevr {@code{dovecot-configuration} parameter} boolean verbose-proctitle?
7486 Show more verbose process titles (in ps). Currently shows user name
7487 and IP address. Useful for seeing who are actually using the IMAP
7488 processes (e.g. shared mailboxes or if same uid is used for multiple
7490 Defaults to @samp{#f}.
7493 @deftypevr {@code{dovecot-configuration} parameter} boolean shutdown-clients?
7494 Should all processes be killed when Dovecot master process shuts down.
7495 Setting this to @code{#f} means that Dovecot can be upgraded without
7496 forcing existing client connections to close (although that could also
7497 be a problem if the upgrade is e.g. because of a security fix).
7498 Defaults to @samp{#t}.
7501 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer doveadm-worker-count
7502 If non-zero, run mail commands via this many connections to doveadm
7503 server, instead of running them directly in the same process.
7504 Defaults to @samp{0}.
7507 @deftypevr {@code{dovecot-configuration} parameter} string doveadm-socket-path
7508 UNIX socket or host:port used for connecting to doveadm server.
7509 Defaults to @samp{"doveadm-server"}.
7512 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list import-environment
7513 List of environment variables that are preserved on Dovecot startup
7514 and passed down to all of its child processes. You can also give
7515 key=value pairs to always set specific settings.
7518 @deftypevr {@code{dovecot-configuration} parameter} boolean disable-plaintext-auth?
7519 Disable LOGIN command and all other plaintext authentications unless
7520 SSL/TLS is used (LOGINDISABLED capability). Note that if the remote IP
7521 matches the local IP (i.e. you're connecting from the same computer),
7522 the connection is considered secure and plaintext authentication is
7523 allowed. See also ssl=required setting.
7524 Defaults to @samp{#t}.
7527 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer auth-cache-size
7528 Authentication cache size (e.g. @samp{#e10e6}). 0 means it's disabled.
7529 Note that bsdauth, PAM and vpopmail require @samp{cache-key} to be set
7530 for caching to be used.
7531 Defaults to @samp{0}.
7534 @deftypevr {@code{dovecot-configuration} parameter} string auth-cache-ttl
7535 Time to live for cached data. After TTL expires the cached record
7536 is no longer used, *except* if the main database lookup returns internal
7537 failure. We also try to handle password changes automatically: If
7538 user's previous authentication was successful, but this one wasn't, the
7539 cache isn't used. For now this works only with plaintext
7541 Defaults to @samp{"1 hour"}.
7544 @deftypevr {@code{dovecot-configuration} parameter} string auth-cache-negative-ttl
7545 TTL for negative hits (user not found, password mismatch).
7546 0 disables caching them completely.
7547 Defaults to @samp{"1 hour"}.
7550 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list auth-realms
7551 List of realms for SASL authentication mechanisms that need them.
7552 You can leave it empty if you don't want to support multiple realms.
7553 Many clients simply use the first one listed here, so keep the default
7555 Defaults to @samp{()}.
7558 @deftypevr {@code{dovecot-configuration} parameter} string auth-default-realm
7559 Default realm/domain to use if none was specified. This is used for
7560 both SASL realms and appending @@domain to username in plaintext
7562 Defaults to @samp{""}.
7565 @deftypevr {@code{dovecot-configuration} parameter} string auth-username-chars
7566 List of allowed characters in username. If the user-given username
7567 contains a character not listed in here, the login automatically fails.
7568 This is just an extra check to make sure user can't exploit any
7569 potential quote escaping vulnerabilities with SQL/LDAP databases. If
7570 you want to allow all characters, set this value to empty.
7571 Defaults to @samp{"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890.-_@@"}.
7574 @deftypevr {@code{dovecot-configuration} parameter} string auth-username-translation
7575 Username character translations before it's looked up from
7576 databases. The value contains series of from -> to characters. For
7577 example @samp{#@@/@@} means that @samp{#} and @samp{/} characters are
7578 translated to @samp{@@}.
7579 Defaults to @samp{""}.
7582 @deftypevr {@code{dovecot-configuration} parameter} string auth-username-format
7583 Username formatting before it's looked up from databases. You can
7584 use the standard variables here, e.g. %Lu would lowercase the username,
7585 %n would drop away the domain if it was given, or @samp{%n-AT-%d} would
7586 change the @samp{@@} into @samp{-AT-}. This translation is done after
7587 @samp{auth-username-translation} changes.
7588 Defaults to @samp{"%Lu"}.
7591 @deftypevr {@code{dovecot-configuration} parameter} string auth-master-user-separator
7592 If you want to allow master users to log in by specifying the master
7593 username within the normal username string (i.e. not using SASL
7594 mechanism's support for it), you can specify the separator character
7595 here. The format is then <username><separator><master username>.
7596 UW-IMAP uses @samp{*} as the separator, so that could be a good
7598 Defaults to @samp{""}.
7601 @deftypevr {@code{dovecot-configuration} parameter} string auth-anonymous-username
7602 Username to use for users logging in with ANONYMOUS SASL
7604 Defaults to @samp{"anonymous"}.
7607 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer auth-worker-max-count
7608 Maximum number of dovecot-auth worker processes. They're used to
7609 execute blocking passdb and userdb queries (e.g. MySQL and PAM).
7610 They're automatically created and destroyed as needed.
7611 Defaults to @samp{30}.
7614 @deftypevr {@code{dovecot-configuration} parameter} string auth-gssapi-hostname
7615 Host name to use in GSSAPI principal names. The default is to use
7616 the name returned by gethostname(). Use @samp{$ALL} (with quotes) to
7617 allow all keytab entries.
7618 Defaults to @samp{""}.
7621 @deftypevr {@code{dovecot-configuration} parameter} string auth-krb5-keytab
7622 Kerberos keytab to use for the GSSAPI mechanism. Will use the
7623 system default (usually /etc/krb5.keytab) if not specified. You may
7624 need to change the auth service to run as root to be able to read this
7626 Defaults to @samp{""}.
7629 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-use-winbind?
7630 Do NTLM and GSS-SPNEGO authentication using Samba's winbind daemon
7631 and @samp{ntlm-auth} helper.
7632 <doc/wiki/Authentication/Mechanisms/Winbind.txt>.
7633 Defaults to @samp{#f}.
7636 @deftypevr {@code{dovecot-configuration} parameter} file-name auth-winbind-helper-path
7637 Path for Samba's @samp{ntlm-auth} helper binary.
7638 Defaults to @samp{"/usr/bin/ntlm_auth"}.
7641 @deftypevr {@code{dovecot-configuration} parameter} string auth-failure-delay
7642 Time to delay before replying to failed authentications.
7643 Defaults to @samp{"2 secs"}.
7646 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-ssl-require-client-cert?
7647 Require a valid SSL client certificate or the authentication
7649 Defaults to @samp{#f}.
7652 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-ssl-username-from-cert?
7653 Take the username from client's SSL certificate, using
7654 @code{X509_NAME_get_text_by_NID()} which returns the subject's DN's
7656 Defaults to @samp{#f}.
7659 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list auth-mechanisms
7660 List of wanted authentication mechanisms. Supported mechanisms are:
7661 @samp{plain}, @samp{login}, @samp{digest-md5}, @samp{cram-md5},
7662 @samp{ntlm}, @samp{rpa}, @samp{apop}, @samp{anonymous}, @samp{gssapi},
7663 @samp{otp}, @samp{skey}, and @samp{gss-spnego}. NOTE: See also
7664 @samp{disable-plaintext-auth} setting.
7667 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list director-servers
7668 List of IPs or hostnames to all director servers, including ourself.
7669 Ports can be specified as ip:port. The default port is the same as what
7670 director service's @samp{inet-listener} is using.
7671 Defaults to @samp{()}.
7674 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list director-mail-servers
7675 List of IPs or hostnames to all backend mail servers. Ranges are
7676 allowed too, like 10.0.0.10-10.0.0.30.
7677 Defaults to @samp{()}.
7680 @deftypevr {@code{dovecot-configuration} parameter} string director-user-expire
7681 How long to redirect users to a specific server after it no longer
7682 has any connections.
7683 Defaults to @samp{"15 min"}.
7686 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer director-doveadm-port
7687 TCP/IP port that accepts doveadm connections (instead of director
7688 connections) If you enable this, you'll also need to add
7689 @samp{inet-listener} for the port.
7690 Defaults to @samp{0}.
7693 @deftypevr {@code{dovecot-configuration} parameter} string director-username-hash
7694 How the username is translated before being hashed. Useful values
7695 include %Ln if user can log in with or without @@domain, %Ld if mailboxes
7696 are shared within domain.
7697 Defaults to @samp{"%Lu"}.
7700 @deftypevr {@code{dovecot-configuration} parameter} string log-path
7701 Log file to use for error messages. @samp{syslog} logs to syslog,
7702 @samp{/dev/stderr} logs to stderr.
7703 Defaults to @samp{"syslog"}.
7706 @deftypevr {@code{dovecot-configuration} parameter} string info-log-path
7707 Log file to use for informational messages. Defaults to
7709 Defaults to @samp{""}.
7712 @deftypevr {@code{dovecot-configuration} parameter} string debug-log-path
7713 Log file to use for debug messages. Defaults to
7714 @samp{info-log-path}.
7715 Defaults to @samp{""}.
7718 @deftypevr {@code{dovecot-configuration} parameter} string syslog-facility
7719 Syslog facility to use if you're logging to syslog. Usually if you
7720 don't want to use @samp{mail}, you'll use local0..local7. Also other
7721 standard facilities are supported.
7722 Defaults to @samp{"mail"}.
7725 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-verbose?
7726 Log unsuccessful authentication attempts and the reasons why they
7728 Defaults to @samp{#f}.
7731 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-verbose-passwords?
7732 In case of password mismatches, log the attempted password. Valid
7733 values are no, plain and sha1. sha1 can be useful for detecting brute
7734 force password attempts vs. user simply trying the same password over
7735 and over again. You can also truncate the value to n chars by appending
7737 Defaults to @samp{#f}.
7740 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-debug?
7741 Even more verbose logging for debugging purposes. Shows for example
7743 Defaults to @samp{#f}.
7746 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-debug-passwords?
7747 In case of password mismatches, log the passwords and used scheme so
7748 the problem can be debugged. Enabling this also enables
7750 Defaults to @samp{#f}.
7753 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-debug?
7754 Enable mail process debugging. This can help you figure out why
7755 Dovecot isn't finding your mails.
7756 Defaults to @samp{#f}.
7759 @deftypevr {@code{dovecot-configuration} parameter} boolean verbose-ssl?
7760 Show protocol level SSL errors.
7761 Defaults to @samp{#f}.
7764 @deftypevr {@code{dovecot-configuration} parameter} string log-timestamp
7765 Prefix for each line written to log file. % codes are in
7767 Defaults to @samp{"\"%b %d %H:%M:%S \""}.
7770 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-log-format-elements
7771 List of elements we want to log. The elements which have a
7772 non-empty variable value are joined together to form a comma-separated
7776 @deftypevr {@code{dovecot-configuration} parameter} string login-log-format
7777 Login log format. %s contains @samp{login-log-format-elements}
7778 string, %$ contains the data we want to log.
7779 Defaults to @samp{"%$: %s"}.
7782 @deftypevr {@code{dovecot-configuration} parameter} string mail-log-prefix
7783 Log prefix for mail processes. See doc/wiki/Variables.txt for list
7784 of possible variables you can use.
7785 Defaults to @samp{"\"%s(%u): \""}.
7788 @deftypevr {@code{dovecot-configuration} parameter} string deliver-log-format
7789 Format to use for logging mail deliveries. You can use variables:
7792 Delivery status message (e.g. @samp{saved to INBOX})
7804 Defaults to @samp{"msgid=%m: %$"}.
7807 @deftypevr {@code{dovecot-configuration} parameter} string mail-location
7808 Location for users' mailboxes. The default is empty, which means
7809 that Dovecot tries to find the mailboxes automatically. This won't work
7810 if the user doesn't yet have any mail, so you should explicitly tell
7811 Dovecot the full location.
7813 If you're using mbox, giving a path to the INBOX
7814 file (e.g. /var/mail/%u) isn't enough. You'll also need to tell Dovecot
7815 where the other mailboxes are kept. This is called the "root mail
7816 directory", and it must be the first path given in the
7817 @samp{mail-location} setting.
7819 There are a few special variables you can use, eg.:
7825 user part in user@@domain, same as %u if there's no domain
7827 domain part in user@@domain, empty if there's no domain
7832 See doc/wiki/Variables.txt for full list. Some examples:
7834 @item maildir:~/Maildir
7835 @item mbox:~/mail:INBOX=/var/mail/%u
7836 @item mbox:/var/mail/%d/%1n/%n:INDEX=/var/indexes/%d/%1n/%
7838 Defaults to @samp{""}.
7841 @deftypevr {@code{dovecot-configuration} parameter} string mail-uid
7842 System user and group used to access mails. If you use multiple,
7843 userdb can override these by returning uid or gid fields. You can use
7844 either numbers or names. <doc/wiki/UserIds.txt>.
7845 Defaults to @samp{""}.
7848 @deftypevr {@code{dovecot-configuration} parameter} string mail-gid
7850 Defaults to @samp{""}.
7853 @deftypevr {@code{dovecot-configuration} parameter} string mail-privileged-group
7854 Group to enable temporarily for privileged operations. Currently
7855 this is used only with INBOX when either its initial creation or
7856 dotlocking fails. Typically this is set to "mail" to give access to
7858 Defaults to @samp{""}.
7861 @deftypevr {@code{dovecot-configuration} parameter} string mail-access-groups
7862 Grant access to these supplementary groups for mail processes.
7863 Typically these are used to set up access to shared mailboxes. Note
7864 that it may be dangerous to set these if users can create
7865 symlinks (e.g. if "mail" group is set here, ln -s /var/mail ~/mail/var
7866 could allow a user to delete others' mailboxes, or ln -s
7867 /secret/shared/box ~/mail/mybox would allow reading it).
7868 Defaults to @samp{""}.
7871 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-full-filesystem-access?
7872 Allow full filesystem access to clients. There's no access checks
7873 other than what the operating system does for the active UID/GID. It
7874 works with both maildir and mboxes, allowing you to prefix mailboxes
7875 names with e.g. /path/ or ~user/.
7876 Defaults to @samp{#f}.
7879 @deftypevr {@code{dovecot-configuration} parameter} boolean mmap-disable?
7880 Don't use mmap() at all. This is required if you store indexes to
7881 shared filesystems (NFS or clustered filesystem).
7882 Defaults to @samp{#f}.
7885 @deftypevr {@code{dovecot-configuration} parameter} boolean dotlock-use-excl?
7886 Rely on @samp{O_EXCL} to work when creating dotlock files. NFS
7887 supports @samp{O_EXCL} since version 3, so this should be safe to use
7888 nowadays by default.
7889 Defaults to @samp{#t}.
7892 @deftypevr {@code{dovecot-configuration} parameter} string mail-fsync
7893 When to use fsync() or fdatasync() calls:
7896 Whenever necessary to avoid losing important data
7898 Useful with e.g. NFS when write()s are delayed
7900 Never use it (best performance, but crashes can lose data).
7902 Defaults to @samp{"optimized"}.
7905 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-nfs-storage?
7906 Mail storage exists in NFS. Set this to yes to make Dovecot flush
7907 NFS caches whenever needed. If you're using only a single mail server
7909 Defaults to @samp{#f}.
7912 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-nfs-index?
7913 Mail index files also exist in NFS. Setting this to yes requires
7914 @samp{mmap-disable? #t} and @samp{fsync-disable? #f}.
7915 Defaults to @samp{#f}.
7918 @deftypevr {@code{dovecot-configuration} parameter} string lock-method
7919 Locking method for index files. Alternatives are fcntl, flock and
7920 dotlock. Dotlocking uses some tricks which may create more disk I/O
7921 than other locking methods. NFS users: flock doesn't work, remember to
7922 change @samp{mmap-disable}.
7923 Defaults to @samp{"fcntl"}.
7926 @deftypevr {@code{dovecot-configuration} parameter} file-name mail-temp-dir
7927 Directory in which LDA/LMTP temporarily stores incoming mails >128
7929 Defaults to @samp{"/tmp"}.
7932 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer first-valid-uid
7933 Valid UID range for users. This is mostly to make sure that users can't
7934 log in as daemons or other system users. Note that denying root logins is
7935 hardcoded to dovecot binary and can't be done even if @samp{first-valid-uid}
7937 Defaults to @samp{500}.
7940 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer last-valid-uid
7942 Defaults to @samp{0}.
7945 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer first-valid-gid
7946 Valid GID range for users. Users having non-valid GID as primary group ID
7947 aren't allowed to log in. If user belongs to supplementary groups with
7948 non-valid GIDs, those groups are not set.
7949 Defaults to @samp{1}.
7952 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer last-valid-gid
7954 Defaults to @samp{0}.
7957 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-max-keyword-length
7958 Maximum allowed length for mail keyword name. It's only forced when
7959 trying to create new keywords.
7960 Defaults to @samp{50}.
7963 @deftypevr {@code{dovecot-configuration} parameter} colon-separated-file-name-list valid-chroot-dirs
7964 List of directories under which chrooting is allowed for mail
7965 processes (i.e. /var/mail will allow chrooting to /var/mail/foo/bar
7966 too). This setting doesn't affect @samp{login-chroot}
7967 @samp{mail-chroot} or auth chroot settings. If this setting is empty,
7968 "/./" in home dirs are ignored. WARNING: Never add directories here
7969 which local users can modify, that may lead to root exploit. Usually
7970 this should be done only if you don't allow shell access for users.
7971 <doc/wiki/Chrooting.txt>.
7972 Defaults to @samp{()}.
7975 @deftypevr {@code{dovecot-configuration} parameter} string mail-chroot
7976 Default chroot directory for mail processes. This can be overridden
7977 for specific users in user database by giving /./ in user's home
7978 directory (e.g. /home/./user chroots into /home). Note that usually
7979 there is no real need to do chrooting, Dovecot doesn't allow users to
7980 access files outside their mail directory anyway. If your home
7981 directories are prefixed with the chroot directory, append "/." to
7982 @samp{mail-chroot}. <doc/wiki/Chrooting.txt>.
7983 Defaults to @samp{""}.
7986 @deftypevr {@code{dovecot-configuration} parameter} file-name auth-socket-path
7987 UNIX socket path to master authentication server to find users.
7988 This is used by imap (for shared users) and lda.
7989 Defaults to @samp{"/var/run/dovecot/auth-userdb"}.
7992 @deftypevr {@code{dovecot-configuration} parameter} file-name mail-plugin-dir
7993 Directory where to look up mail plugins.
7994 Defaults to @samp{"/usr/lib/dovecot"}.
7997 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mail-plugins
7998 List of plugins to load for all services. Plugins specific to IMAP,
7999 LDA, etc. are added to this list in their own .conf files.
8000 Defaults to @samp{()}.
8003 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-cache-min-mail-count
8004 The minimum number of mails in a mailbox before updates are done to
8005 cache file. This allows optimizing Dovecot's behavior to do less disk
8006 writes at the cost of more disk reads.
8007 Defaults to @samp{0}.
8010 @deftypevr {@code{dovecot-configuration} parameter} string mailbox-idle-check-interval
8011 When IDLE command is running, mailbox is checked once in a while to
8012 see if there are any new mails or other changes. This setting defines
8013 the minimum time to wait between those checks. Dovecot can also use
8014 dnotify, inotify and kqueue to find out immediately when changes
8016 Defaults to @samp{"30 secs"}.
8019 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-save-crlf?
8020 Save mails with CR+LF instead of plain LF. This makes sending those
8021 mails take less CPU, especially with sendfile() syscall with Linux and
8022 FreeBSD. But it also creates a bit more disk I/O which may just make it
8023 slower. Also note that if other software reads the mboxes/maildirs,
8024 they may handle the extra CRs wrong and cause problems.
8025 Defaults to @samp{#f}.
8028 @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-stat-dirs?
8029 By default LIST command returns all entries in maildir beginning
8030 with a dot. Enabling this option makes Dovecot return only entries
8031 which are directories. This is done by stat()ing each entry, so it
8032 causes more disk I/O.
8033 (For systems setting struct @samp{dirent->d_type} this check is free
8034 and it's done always regardless of this setting).
8035 Defaults to @samp{#f}.
8038 @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-copy-with-hardlinks?
8039 When copying a message, do it with hard links whenever possible.
8040 This makes the performance much better, and it's unlikely to have any
8042 Defaults to @samp{#t}.
8045 @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-very-dirty-syncs?
8046 Assume Dovecot is the only MUA accessing Maildir: Scan cur/
8047 directory only when its mtime changes unexpectedly or when we can't find
8049 Defaults to @samp{#f}.
8052 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mbox-read-locks
8053 Which locking methods to use for locking mbox. There are four
8058 Create <mailbox>.lock file. This is the oldest and most NFS-safe
8059 solution. If you want to use /var/mail/ like directory, the users will
8060 need write access to that directory.
8062 Same as dotlock, but if it fails because of permissions or because there
8063 isn't enough disk space, just skip it.
8065 Use this if possible. Works with NFS too if lockd is used.
8067 May not exist in all systems. Doesn't work with NFS.
8069 May not exist in all systems. Doesn't work with NFS.
8072 You can use multiple locking methods; if you do the order they're declared
8073 in is important to avoid deadlocks if other MTAs/MUAs are using multiple
8074 locking methods as well. Some operating systems don't allow using some of
8075 them simultaneously.
8078 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mbox-write-locks
8082 @deftypevr {@code{dovecot-configuration} parameter} string mbox-lock-timeout
8083 Maximum time to wait for lock (all of them) before aborting.
8084 Defaults to @samp{"5 mins"}.
8087 @deftypevr {@code{dovecot-configuration} parameter} string mbox-dotlock-change-timeout
8088 If dotlock exists but the mailbox isn't modified in any way,
8089 override the lock file after this much time.
8090 Defaults to @samp{"2 mins"}.
8093 @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-dirty-syncs?
8094 When mbox changes unexpectedly we have to fully read it to find out
8095 what changed. If the mbox is large this can take a long time. Since
8096 the change is usually just a newly appended mail, it'd be faster to
8097 simply read the new mails. If this setting is enabled, Dovecot does
8098 this but still safely fallbacks to re-reading the whole mbox file
8099 whenever something in mbox isn't how it's expected to be. The only real
8100 downside to this setting is that if some other MUA changes message
8101 flags, Dovecot doesn't notice it immediately. Note that a full sync is
8102 done with SELECT, EXAMINE, EXPUNGE and CHECK commands.
8103 Defaults to @samp{#t}.
8106 @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-very-dirty-syncs?
8107 Like @samp{mbox-dirty-syncs}, but don't do full syncs even with SELECT,
8108 EXAMINE, EXPUNGE or CHECK commands. If this is set,
8109 @samp{mbox-dirty-syncs} is ignored.
8110 Defaults to @samp{#f}.
8113 @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-lazy-writes?
8114 Delay writing mbox headers until doing a full write sync (EXPUNGE
8115 and CHECK commands and when closing the mailbox). This is especially
8116 useful for POP3 where clients often delete all mails. The downside is
8117 that our changes aren't immediately visible to other MUAs.
8118 Defaults to @samp{#t}.
8121 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mbox-min-index-size
8122 If mbox size is smaller than this (e.g. 100k), don't write index
8123 files. If an index file already exists it's still read, just not
8125 Defaults to @samp{0}.
8128 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mdbox-rotate-size
8129 Maximum dbox file size until it's rotated.
8130 Defaults to @samp{2000000}.
8133 @deftypevr {@code{dovecot-configuration} parameter} string mdbox-rotate-interval
8134 Maximum dbox file age until it's rotated. Typically in days. Day
8135 begins from midnight, so 1d = today, 2d = yesterday, etc. 0 = check
8137 Defaults to @samp{"1d"}.
8140 @deftypevr {@code{dovecot-configuration} parameter} boolean mdbox-preallocate-space?
8141 When creating new mdbox files, immediately preallocate their size to
8142 @samp{mdbox-rotate-size}. This setting currently works only in Linux
8143 with some filesystems (ext4, xfs).
8144 Defaults to @samp{#f}.
8147 @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-dir
8148 sdbox and mdbox support saving mail attachments to external files,
8149 which also allows single instance storage for them. Other backends
8150 don't support this for now.
8152 WARNING: This feature hasn't been tested much yet. Use at your own risk.
8154 Directory root where to store mail attachments. Disabled, if empty.
8155 Defaults to @samp{""}.
8158 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-attachment-min-size
8159 Attachments smaller than this aren't saved externally. It's also
8160 possible to write a plugin to disable saving specific attachments
8162 Defaults to @samp{128000}.
8165 @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-fs
8166 Filesystem backend to use for saving attachments:
8169 No SiS done by Dovecot (but this might help FS's own deduplication)
8171 SiS with immediate byte-by-byte comparison during saving
8172 @item sis-queue posix
8173 SiS with delayed comparison and deduplication.
8175 Defaults to @samp{"sis posix"}.
8178 @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-hash
8179 Hash format to use in attachment filenames. You can add any text and
8180 variables: @code{%@{md4@}}, @code{%@{md5@}}, @code{%@{sha1@}},
8181 @code{%@{sha256@}}, @code{%@{sha512@}}, @code{%@{size@}}. Variables can be
8182 truncated, e.g. @code{%@{sha256:80@}} returns only first 80 bits.
8183 Defaults to @samp{"%@{sha1@}"}.
8186 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-process-limit
8188 Defaults to @samp{100}.
8191 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-client-limit
8193 Defaults to @samp{1000}.
8196 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-vsz-limit
8197 Default VSZ (virtual memory size) limit for service processes.
8198 This is mainly intended to catch and kill processes that leak memory
8199 before they eat up everything.
8200 Defaults to @samp{256000000}.
8203 @deftypevr {@code{dovecot-configuration} parameter} string default-login-user
8204 Login user is internally used by login processes. This is the most
8205 untrusted user in Dovecot system. It shouldn't have access to anything
8207 Defaults to @samp{"dovenull"}.
8210 @deftypevr {@code{dovecot-configuration} parameter} string default-internal-user
8211 Internal user is used by unprivileged processes. It should be
8212 separate from login user, so that login processes can't disturb other
8214 Defaults to @samp{"dovecot"}.
8217 @deftypevr {@code{dovecot-configuration} parameter} string ssl?
8218 SSL/TLS support: yes, no, required. <doc/wiki/SSL.txt>.
8219 Defaults to @samp{"required"}.
8222 @deftypevr {@code{dovecot-configuration} parameter} string ssl-cert
8223 PEM encoded X.509 SSL/TLS certificate (public key).
8224 Defaults to @samp{"</etc/dovecot/default.pem"}.
8227 @deftypevr {@code{dovecot-configuration} parameter} string ssl-key
8228 PEM encoded SSL/TLS private key. The key is opened before
8229 dropping root privileges, so keep the key file unreadable by anyone but
8231 Defaults to @samp{"</etc/dovecot/private/default.pem"}.
8234 @deftypevr {@code{dovecot-configuration} parameter} string ssl-key-password
8235 If key file is password protected, give the password here.
8236 Alternatively give it when starting dovecot with -p parameter. Since
8237 this file is often world-readable, you may want to place this setting
8238 instead to a different.
8239 Defaults to @samp{""}.
8242 @deftypevr {@code{dovecot-configuration} parameter} string ssl-ca
8243 PEM encoded trusted certificate authority. Set this only if you
8244 intend to use @samp{ssl-verify-client-cert? #t}. The file should
8245 contain the CA certificate(s) followed by the matching
8246 CRL(s). (e.g. @samp{ssl-ca </etc/ssl/certs/ca.pem}).
8247 Defaults to @samp{""}.
8250 @deftypevr {@code{dovecot-configuration} parameter} boolean ssl-require-crl?
8251 Require that CRL check succeeds for client certificates.
8252 Defaults to @samp{#t}.
8255 @deftypevr {@code{dovecot-configuration} parameter} boolean ssl-verify-client-cert?
8256 Request client to send a certificate. If you also want to require
8257 it, set @samp{auth-ssl-require-client-cert? #t} in auth section.
8258 Defaults to @samp{#f}.
8261 @deftypevr {@code{dovecot-configuration} parameter} string ssl-cert-username-field
8262 Which field from certificate to use for username. commonName and
8263 x500UniqueIdentifier are the usual choices. You'll also need to set
8264 @samp{auth-ssl-username-from-cert? #t}.
8265 Defaults to @samp{"commonName"}.
8268 @deftypevr {@code{dovecot-configuration} parameter} hours ssl-parameters-regenerate
8269 How often to regenerate the SSL parameters file. Generation is
8270 quite CPU intensive operation. The value is in hours, 0 disables
8271 regeneration entirely.
8272 Defaults to @samp{168}.
8275 @deftypevr {@code{dovecot-configuration} parameter} string ssl-protocols
8276 SSL protocols to use.
8277 Defaults to @samp{"!SSLv2"}.
8280 @deftypevr {@code{dovecot-configuration} parameter} string ssl-cipher-list
8282 Defaults to @samp{"ALL:!LOW:!SSLv2:!EXP:!aNULL"}.
8285 @deftypevr {@code{dovecot-configuration} parameter} string ssl-crypto-device
8286 SSL crypto device to use, for valid values run "openssl engine".
8287 Defaults to @samp{""}.
8290 @deftypevr {@code{dovecot-configuration} parameter} string postmaster-address
8291 Address to use when sending rejection mails.
8292 Default is postmaster@@<your domain>. %d expands to recipient domain.
8293 Defaults to @samp{""}.
8296 @deftypevr {@code{dovecot-configuration} parameter} string hostname
8297 Hostname to use in various parts of sent mails (e.g. in Message-Id)
8298 and in LMTP replies. Default is the system's real hostname@@domain.
8299 Defaults to @samp{""}.
8302 @deftypevr {@code{dovecot-configuration} parameter} boolean quota-full-tempfail?
8303 If user is over quota, return with temporary failure instead of
8305 Defaults to @samp{#f}.
8308 @deftypevr {@code{dovecot-configuration} parameter} file-name sendmail-path
8309 Binary to use for sending mails.
8310 Defaults to @samp{"/usr/sbin/sendmail"}.
8313 @deftypevr {@code{dovecot-configuration} parameter} string submission-host
8314 If non-empty, send mails via this SMTP host[:port] instead of
8316 Defaults to @samp{""}.
8319 @deftypevr {@code{dovecot-configuration} parameter} string rejection-subject
8320 Subject: header to use for rejection mails. You can use the same
8321 variables as for @samp{rejection-reason} below.
8322 Defaults to @samp{"Rejected: %s"}.
8325 @deftypevr {@code{dovecot-configuration} parameter} string rejection-reason
8326 Human readable error message for rejection mails. You can use
8339 Defaults to @samp{"Your message to <%t> was automatically rejected:%n%r"}.
8342 @deftypevr {@code{dovecot-configuration} parameter} string recipient-delimiter
8343 Delimiter character between local-part and detail in email
8345 Defaults to @samp{"+"}.
8348 @deftypevr {@code{dovecot-configuration} parameter} string lda-original-recipient-header
8349 Header where the original recipient address (SMTP's RCPT TO:
8350 address) is taken from if not available elsewhere. With dovecot-lda -a
8351 parameter overrides this. A commonly used header for this is
8353 Defaults to @samp{""}.
8356 @deftypevr {@code{dovecot-configuration} parameter} boolean lda-mailbox-autocreate?
8357 Should saving a mail to a nonexistent mailbox automatically create
8359 Defaults to @samp{#f}.
8362 @deftypevr {@code{dovecot-configuration} parameter} boolean lda-mailbox-autosubscribe?
8363 Should automatically created mailboxes be also automatically
8365 Defaults to @samp{#f}.
8368 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer imap-max-line-length
8369 Maximum IMAP command line length. Some clients generate very long
8370 command lines with huge mailboxes, so you may need to raise this if you
8371 get "Too long argument" or "IMAP command line too large" errors
8373 Defaults to @samp{64000}.
8376 @deftypevr {@code{dovecot-configuration} parameter} string imap-logout-format
8377 IMAP logout format string:
8380 total number of bytes read from client
8382 total number of bytes sent to client.
8384 Defaults to @samp{"in=%i out=%o"}.
8387 @deftypevr {@code{dovecot-configuration} parameter} string imap-capability
8388 Override the IMAP CAPABILITY response. If the value begins with '+',
8389 add the given capabilities on top of the defaults (e.g. +XFOO XBAR).
8390 Defaults to @samp{""}.
8393 @deftypevr {@code{dovecot-configuration} parameter} string imap-idle-notify-interval
8394 How long to wait between "OK Still here" notifications when client
8396 Defaults to @samp{"2 mins"}.
8399 @deftypevr {@code{dovecot-configuration} parameter} string imap-id-send
8400 ID field names and values to send to clients. Using * as the value
8401 makes Dovecot use the default value. The following fields have default
8402 values currently: name, version, os, os-version, support-url,
8404 Defaults to @samp{""}.
8407 @deftypevr {@code{dovecot-configuration} parameter} string imap-id-log
8408 ID fields sent by client to log. * means everything.
8409 Defaults to @samp{""}.
8412 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list imap-client-workarounds
8413 Workarounds for various client bugs:
8417 Send EXISTS/RECENT new mail notifications only when replying to NOOP and
8418 CHECK commands. Some clients ignore them otherwise, for example OSX
8419 Mail (<v2.1). Outlook Express breaks more badly though, without this it
8420 may show user "Message no longer in server" errors. Note that OE6
8421 still breaks even with this workaround if synchronization is set to
8424 @item tb-extra-mailbox-sep
8425 Thunderbird gets somehow confused with LAYOUT=fs (mbox and dbox) and
8426 adds extra @samp{/} suffixes to mailbox names. This option causes Dovecot to
8427 ignore the extra @samp{/} instead of treating it as invalid mailbox name.
8430 Show \Noselect flags for LSUB replies with LAYOUT=fs (e.g. mbox).
8431 This makes Thunderbird realize they aren't selectable and show them
8432 greyed out, instead of only later giving "not selectable" popup error.
8434 Defaults to @samp{()}.
8437 @deftypevr {@code{dovecot-configuration} parameter} string imap-urlauth-host
8438 Host allowed in URLAUTH URLs sent by client. "*" allows all.
8439 Defaults to @samp{""}.
8443 Whew! Lots of configuration options. The nice thing about it though is
8444 that GuixSD has a complete interface to Dovecot's configuration
8445 language. This allows not only a nice way to declare configurations,
8446 but also offers reflective capabilities as well: users can write code to
8447 inspect and transform configurations from within Scheme.
8449 However, it could be that you just want to get a @code{dovecot.conf} up
8450 and running. In that case, you can pass an
8451 @code{opaque-dovecot-configuration} as the @code{#:config} paramter to
8452 @code{dovecot-service}. As its name indicates, an opaque configuration
8453 does not have easy reflective capabilities.
8455 Available @code{opaque-dovecot-configuration} fields are:
8457 @deftypevr {@code{opaque-dovecot-configuration} parameter} package dovecot
8458 The dovecot package.
8461 @deftypevr {@code{opaque-dovecot-configuration} parameter} string string
8462 The contents of the @code{dovecot.conf}, as a string.
8465 For example, if your @code{dovecot.conf} is just the empty string, you
8466 could instantiate a dovecot service like this:
8469 (dovecot-service #:config
8470 (opaque-dovecot-configuration
8475 @subsubsection Web Services
8477 The @code{(gnu services web)} module provides the following service:
8479 @deffn {Scheme Procedure} nginx-service [#:nginx nginx] @
8480 [#:log-directory ``/var/log/nginx''] @
8481 [#:run-directory ``/var/run/nginx''] @
8484 Return a service that runs @var{nginx}, the nginx web server.
8486 The nginx daemon loads its runtime configuration from @var{config-file}.
8487 Log files are written to @var{log-directory} and temporary runtime data
8488 files are written to @var{run-directory}. For proper operation, these
8489 arguments should match what is in @var{config-file} to ensure that the
8490 directories are created when the service is activated.
8494 @node Various Services
8495 @subsubsection Various Services
8497 The @code{(gnu services lirc)} module provides the following service.
8499 @deffn {Scheme Procedure} lirc-service [#:lirc lirc] @
8500 [#:device #f] [#:driver #f] [#:config-file #f] @
8501 [#:extra-options '()]
8502 Return a service that runs @url{http://www.lirc.org,LIRC}, a daemon that
8503 decodes infrared signals from remote controls.
8505 Optionally, @var{device}, @var{driver} and @var{config-file}
8506 (configuration file name) may be specified. See @command{lircd} manual
8509 Finally, @var{extra-options} is a list of additional command-line options
8510 passed to @command{lircd}.
8514 @node Setuid Programs
8515 @subsection Setuid Programs
8517 @cindex setuid programs
8518 Some programs need to run with ``root'' privileges, even when they are
8519 launched by unprivileged users. A notorious example is the
8520 @command{passwd} program, which users can run to change their
8521 password, and which needs to access the @file{/etc/passwd} and
8522 @file{/etc/shadow} files---something normally restricted to root, for
8523 obvious security reasons. To address that, these executables are
8524 @dfn{setuid-root}, meaning that they always run with root privileges
8525 (@pxref{How Change Persona,,, libc, The GNU C Library Reference Manual},
8526 for more info about the setuid mechanism.)
8528 The store itself @emph{cannot} contain setuid programs: that would be a
8529 security issue since any user on the system can write derivations that
8530 populate the store (@pxref{The Store}). Thus, a different mechanism is
8531 used: instead of changing the setuid bit directly on files that are in
8532 the store, we let the system administrator @emph{declare} which programs
8533 should be setuid root.
8535 The @code{setuid-programs} field of an @code{operating-system}
8536 declaration contains a list of G-expressions denoting the names of
8537 programs to be setuid-root (@pxref{Using the Configuration System}).
8538 For instance, the @command{passwd} program, which is part of the Shadow
8539 package, can be designated by this G-expression (@pxref{G-Expressions}):
8542 #~(string-append #$shadow "/bin/passwd")
8545 A default set of setuid programs is defined by the
8546 @code{%setuid-programs} variable of the @code{(gnu system)} module.
8548 @defvr {Scheme Variable} %setuid-programs
8549 A list of G-expressions denoting common programs that are setuid-root.
8551 The list includes commands such as @command{passwd}, @command{ping},
8552 @command{su}, and @command{sudo}.
8555 Under the hood, the actual setuid programs are created in the
8556 @file{/run/setuid-programs} directory at system activation time. The
8557 files in this directory refer to the ``real'' binaries, which are in the
8560 @node X.509 Certificates
8561 @subsection X.509 Certificates
8563 @cindex HTTPS, certificates
8564 @cindex X.509 certificates
8566 Web servers available over HTTPS (that is, HTTP over the transport-layer
8567 security mechanism, TLS) send client programs an @dfn{X.509 certificate}
8568 that the client can then use to @emph{authenticate} the server. To do
8569 that, clients verify that the server's certificate is signed by a
8570 so-called @dfn{certificate authority} (CA). But to verify the CA's
8571 signature, clients must have first acquired the CA's certificate.
8573 Web browsers such as GNU@tie{}IceCat include their own set of CA
8574 certificates, such that they are able to verify CA signatures
8577 However, most other programs that can talk HTTPS---@command{wget},
8578 @command{git}, @command{w3m}, etc.---need to be told where CA
8579 certificates can be found.
8581 @cindex @code{nss-certs}
8582 In GuixSD, this is done by adding a package that provides certificates
8583 to the @code{packages} field of the @code{operating-system} declaration
8584 (@pxref{operating-system Reference}). GuixSD includes one such package,
8585 @code{nss-certs}, which is a set of CA certificates provided as part of
8586 Mozilla's Network Security Services.
8588 Note that it is @emph{not} part of @var{%base-packages}, so you need to
8589 explicitly add it. The @file{/etc/ssl/certs} directory, which is where
8590 most applications and libraries look for certificates by default, points
8591 to the certificates installed globally.
8593 Unprivileged users can also install their own certificate package in
8594 their profile. A number of environment variables need to be defined so
8595 that applications and libraries know where to find them. Namely, the
8596 OpenSSL library honors the @code{SSL_CERT_DIR} and @code{SSL_CERT_FILE}
8597 variables. Some applications add their own environment variables; for
8598 instance, the Git version control system honors the certificate bundle
8599 pointed to by the @code{GIT_SSL_CAINFO} environment variable.
8602 @node Name Service Switch
8603 @subsection Name Service Switch
8605 @cindex name service switch
8607 The @code{(gnu system nss)} module provides bindings to the
8608 configuration file of libc's @dfn{name service switch} or @dfn{NSS}
8609 (@pxref{NSS Configuration File,,, libc, The GNU C Library Reference
8610 Manual}). In a nutshell, the NSS is a mechanism that allows libc to be
8611 extended with new ``name'' lookup methods for system databases, which
8612 includes host names, service names, user accounts, and more (@pxref{Name
8613 Service Switch, System Databases and Name Service Switch,, libc, The GNU
8614 C Library Reference Manual}).
8616 The NSS configuration specifies, for each system database, which lookup
8617 method is to be used, and how the various methods are chained
8618 together---for instance, under which circumstances NSS should try the
8619 next method in the list. The NSS configuration is given in the
8620 @code{name-service-switch} field of @code{operating-system} declarations
8621 (@pxref{operating-system Reference, @code{name-service-switch}}).
8624 @cindex .local, host name lookup
8625 As an example, the declaration below configures the NSS to use the
8626 @uref{http://0pointer.de/lennart/projects/nss-mdns/, @code{nss-mdns}
8627 back-end}, which supports host name lookups over multicast DNS (mDNS)
8628 for host names ending in @code{.local}:
8631 (name-service-switch
8632 (hosts (list %files ;first, check /etc/hosts
8634 ;; If the above did not succeed, try
8635 ;; with 'mdns_minimal'.
8637 (name "mdns_minimal")
8639 ;; 'mdns_minimal' is authoritative for
8640 ;; '.local'. When it returns "not found",
8641 ;; no need to try the next methods.
8642 (reaction (lookup-specification
8643 (not-found => return))))
8645 ;; Then fall back to DNS.
8649 ;; Finally, try with the "full" 'mdns'.
8654 Don't worry: the @code{%mdns-host-lookup-nss} variable (see below)
8655 contains this configuration, so you won't have to type it if all you
8656 want is to have @code{.local} host lookup working.
8658 Note that, in this case, in addition to setting the
8659 @code{name-service-switch} of the @code{operating-system} declaration,
8660 you also need to use @code{avahi-service} (@pxref{Networking Services,
8661 @code{avahi-service}}), or @var{%desktop-services}, which includes it
8662 (@pxref{Desktop Services}). Doing this makes @code{nss-mdns} accessible
8663 to the name service cache daemon (@pxref{Base Services,
8664 @code{nscd-service}}).
8666 For convenience, the following variables provide typical NSS
8669 @defvr {Scheme Variable} %default-nss
8670 This is the default name service switch configuration, a
8671 @code{name-service-switch} object.
8674 @defvr {Scheme Variable} %mdns-host-lookup-nss
8675 This is the name service switch configuration with support for host name
8676 lookup over multicast DNS (mDNS) for host names ending in @code{.local}.
8679 The reference for name service switch configuration is given below. It
8680 is a direct mapping of the C library's configuration file format, so
8681 please refer to the C library manual for more information (@pxref{NSS
8682 Configuration File,,, libc, The GNU C Library Reference Manual}).
8683 Compared to libc's NSS configuration file format, it has the advantage
8684 not only of adding this warm parenthetic feel that we like, but also
8685 static checks: you'll know about syntax errors and typos as soon as you
8686 run @command{guix system}.
8688 @deftp {Data Type} name-service-switch
8690 This is the data type representation the configuration of libc's name
8691 service switch (NSS). Each field below represents one of the supported
8708 The system databases handled by the NSS. Each of these fields must be a
8709 list of @code{<name-service>} objects (see below.)
8713 @deftp {Data Type} name-service
8715 This is the data type representing an actual name service and the
8716 associated lookup action.
8720 A string denoting the name service (@pxref{Services in the NSS
8721 configuration,,, libc, The GNU C Library Reference Manual}).
8723 Note that name services listed here must be visible to nscd. This is
8724 achieved by passing the @code{#:name-services} argument to
8725 @code{nscd-service} the list of packages providing the needed name
8726 services (@pxref{Base Services, @code{nscd-service}}).
8729 An action specified using the @code{lookup-specification} macro
8730 (@pxref{Actions in the NSS configuration,,, libc, The GNU C Library
8731 Reference Manual}). For example:
8734 (lookup-specification (unavailable => continue)
8735 (success => return))
8740 @node Initial RAM Disk
8741 @subsection Initial RAM Disk
8743 @cindex initial RAM disk (initrd)
8744 @cindex initrd (initial RAM disk)
8745 For bootstrapping purposes, the Linux-Libre kernel is passed an
8746 @dfn{initial RAM disk}, or @dfn{initrd}. An initrd contains a temporary
8747 root file system, as well as an initialization script. The latter is
8748 responsible for mounting the real root file system, and for loading any
8749 kernel modules that may be needed to achieve that.
8751 The @code{initrd} field of an @code{operating-system} declaration allows
8752 you to specify which initrd you would like to use. The @code{(gnu
8753 system linux-initrd)} module provides two ways to build an initrd: the
8754 high-level @code{base-initrd} procedure, and the low-level
8755 @code{expression->initrd} procedure.
8757 The @code{base-initrd} procedure is intended to cover most common uses.
8758 For example, if you want to add a bunch of kernel modules to be loaded
8759 at boot time, you can define the @code{initrd} field of the operating
8760 system declaration like this:
8763 (initrd (lambda (file-systems . rest)
8764 ;; Create a standard initrd that has modules "foo.ko"
8765 ;; and "bar.ko", as well as their dependencies, in
8766 ;; addition to the modules available by default.
8767 (apply base-initrd file-systems
8768 #:extra-modules '("foo" "bar")
8772 The @code{base-initrd} procedure also handles common use cases that
8773 involves using the system as a QEMU guest, or as a ``live'' system whose
8774 root file system is volatile.
8776 @deffn {Monadic Procedure} base-initrd @var{file-systems} @
8777 [#:qemu-networking? #f] [#:virtio? #f] [#:volatile-root? #f] @
8778 [#:extra-modules '()] [#:mapped-devices '()]
8779 Return a monadic derivation that builds a generic initrd. @var{file-systems} is
8780 a list of file-systems to be mounted by the initrd, possibly in addition to
8781 the root file system specified on the kernel command line via @code{--root}.
8782 @var{mapped-devices} is a list of device mappings to realize before
8783 @var{file-systems} are mounted (@pxref{Mapped Devices}).
8785 When @var{qemu-networking?} is true, set up networking with the standard QEMU
8786 parameters. When @var{virtio?} is true, load additional modules so the initrd can
8787 be used as a QEMU guest with para-virtualized I/O drivers.
8789 When @var{volatile-root?} is true, the root file system is writable but any changes
8792 The initrd is automatically populated with all the kernel modules necessary
8793 for @var{file-systems} and for the given options. However, additional kernel
8794 modules can be listed in @var{extra-modules}. They will be added to the initrd, and
8795 loaded at boot time in the order in which they appear.
8798 Needless to say, the initrds we produce and use embed a
8799 statically-linked Guile, and the initialization program is a Guile
8800 program. That gives a lot of flexibility. The
8801 @code{expression->initrd} procedure builds such an initrd, given the
8802 program to run in that initrd.
8804 @deffn {Monadic Procedure} expression->initrd @var{exp} @
8805 [#:guile %guile-static-stripped] [#:name "guile-initrd"] @
8807 Return a derivation that builds a Linux initrd (a gzipped cpio archive)
8808 containing @var{guile} and that evaluates @var{exp}, a G-expression,
8809 upon booting. All the derivations referenced by @var{exp} are
8810 automatically copied to the initrd.
8812 @var{modules} is a list of Guile module names to be embedded in the
8816 @node GRUB Configuration
8817 @subsection GRUB Configuration
8822 The operating system uses GNU@tie{}GRUB as its boot loader
8823 (@pxref{Overview, overview of GRUB,, grub, GNU GRUB Manual}). It is
8824 configured using @code{grub-configuration} declarations. This data type
8825 is exported by the @code{(gnu system grub)} module, and described below.
8827 @deftp {Data Type} grub-configuration
8828 The type of a GRUB configuration declaration.
8833 This is a string denoting the boot device. It must be a device name
8834 understood by the @command{grub-install} command, such as
8835 @code{/dev/sda} or @code{(hd0)} (@pxref{Invoking grub-install,,, grub,
8838 @item @code{menu-entries} (default: @code{()})
8839 A possibly empty list of @code{menu-entry} objects (see below), denoting
8840 entries to appear in the GRUB boot menu, in addition to the current
8841 system entry and the entry pointing to previous system generations.
8843 @item @code{default-entry} (default: @code{0})
8844 The index of the default boot menu entry. Index 0 is for the current
8847 @item @code{timeout} (default: @code{5})
8848 The number of seconds to wait for keyboard input before booting. Set to
8849 0 to boot immediately, and to -1 to wait indefinitely.
8851 @item @code{theme} (default: @var{%default-theme})
8852 The @code{grub-theme} object describing the theme to use.
8857 Should you want to list additional boot menu entries @i{via} the
8858 @code{menu-entries} field above, you will need to create them with the
8859 @code{menu-entry} form:
8861 @deftp {Data Type} menu-entry
8862 The type of an entry in the GRUB boot menu.
8867 The label to show in the menu---e.g., @code{"GNU"}.
8870 The Linux kernel to boot.
8872 @item @code{linux-arguments} (default: @code{()})
8873 The list of extra Linux kernel command-line arguments---e.g.,
8874 @code{("console=ttyS0")}.
8877 A G-Expression or string denoting the file name of the initial RAM disk
8878 to use (@pxref{G-Expressions}).
8883 @c FIXME: Write documentation once it's stable.
8884 Themes are created using the @code{grub-theme} form, which is not
8887 @defvr {Scheme Variable} %default-theme
8888 This is the default GRUB theme used by the operating system, with a
8889 fancy background image displaying the GNU and Guix logos.
8893 @node Invoking guix system
8894 @subsection Invoking @code{guix system}
8896 Once you have written an operating system declaration, as seen in the
8897 previous section, it can be @dfn{instantiated} using the @command{guix
8898 system} command. The synopsis is:
8901 guix system @var{options}@dots{} @var{action} @var{file}
8904 @var{file} must be the name of a file containing an
8905 @code{operating-system} declaration. @var{action} specifies how the
8906 operating system is instantiate. Currently the following values are
8911 Build the operating system described in @var{file}, activate it, and
8912 switch to it@footnote{This action is usable only on systems already
8915 This effects all the configuration specified in @var{file}: user
8916 accounts, system services, global package list, setuid programs, etc.
8918 It also adds a GRUB menu entry for the new OS configuration, and moves
8919 entries for older configurations to a submenu---unless
8920 @option{--no-grub} is passed.
8922 @c The paragraph below refers to the problem discussed at
8923 @c <http://lists.gnu.org/archive/html/guix-devel/2014-08/msg00057.html>.
8924 It is highly recommended to run @command{guix pull} once before you run
8925 @command{guix system reconfigure} for the first time (@pxref{Invoking
8926 guix pull}). Failing to do that you would see an older version of Guix
8927 once @command{reconfigure} has completed.
8930 Build the operating system's derivation, which includes all the
8931 configuration files and programs needed to boot and run the system.
8932 This action does not actually install anything.
8935 Populate the given directory with all the files necessary to run the
8936 operating system specified in @var{file}. This is useful for first-time
8937 installations of GuixSD. For instance:
8940 guix system init my-os-config.scm /mnt
8943 copies to @file{/mnt} all the store items required by the configuration
8944 specified in @file{my-os-config.scm}. This includes configuration
8945 files, packages, and so on. It also creates other essential files
8946 needed for the system to operate correctly---e.g., the @file{/etc},
8947 @file{/var}, and @file{/run} directories, and the @file{/bin/sh} file.
8949 This command also installs GRUB on the device specified in
8950 @file{my-os-config}, unless the @option{--no-grub} option was passed.
8953 @cindex virtual machine
8955 @anchor{guix system vm}
8956 Build a virtual machine that contain the operating system declared in
8957 @var{file}, and return a script to run that virtual machine (VM).
8958 Arguments given to the script are passed as is to QEMU.
8960 The VM shares its store with the host system.
8962 Additional file systems can be shared between the host and the VM using
8963 the @code{--share} and @code{--expose} command-line options: the former
8964 specifies a directory to be shared with write access, while the latter
8965 provides read-only access to the shared directory.
8967 The example below creates a VM in which the user's home directory is
8968 accessible read-only, and where the @file{/exchange} directory is a
8969 read-write mapping of the host's @file{$HOME/tmp}:
8972 guix system vm my-config.scm \
8973 --expose=$HOME --share=$HOME/tmp=/exchange
8976 On GNU/Linux, the default is to boot directly to the kernel; this has
8977 the advantage of requiring only a very tiny root disk image since the
8978 host's store can then be mounted.
8980 The @code{--full-boot} option forces a complete boot sequence, starting
8981 with the bootloader. This requires more disk space since a root image
8982 containing at least the kernel, initrd, and bootloader data files must
8983 be created. The @code{--image-size} option can be used to specify the
8988 Return a virtual machine or disk image of the operating system declared
8989 in @var{file} that stands alone. Use the @option{--image-size} option
8990 to specify the size of the image.
8992 When using @code{vm-image}, the returned image is in qcow2 format, which
8993 the QEMU emulator can efficiently use.
8995 When using @code{disk-image}, a raw disk image is produced; it can be
8996 copied as is to a USB stick, for instance. Assuming @code{/dev/sdc} is
8997 the device corresponding to a USB stick, one can copy the image on it
8998 using the following command:
9001 # dd if=$(guix system disk-image my-os.scm) of=/dev/sdc
9005 Return a script to run the operating system declared in @var{file}
9006 within a container. Containers are a set of lightweight isolation
9007 mechanisms provided by the kernel Linux-libre. Containers are
9008 substantially less resource-demanding than full virtual machines since
9009 the kernel, shared objects, and other resources can be shared with the
9010 host system; this also means they provide thinner isolation.
9012 Currently, the script must be run as root in order to support more than
9013 a single user and group. The container shares its store with the host
9016 As with the @code{vm} action (@pxref{guix system vm}), additional file
9017 systems to be shared between the host and container can be specified
9018 using the @option{--share} and @option{--expose} options:
9021 guix system container my-config.scm \
9022 --expose=$HOME --share=$HOME/tmp=/exchange
9026 This option requires Linux-libre 3.19 or newer.
9031 @var{options} can contain any of the common build options provided by
9032 @command{guix build} (@pxref{Invoking guix build}). In addition,
9033 @var{options} can contain one of the following:
9036 @item --system=@var{system}
9037 @itemx -s @var{system}
9038 Attempt to build for @var{system} instead of the host's system type.
9039 This works as per @command{guix build} (@pxref{Invoking guix build}).
9043 Return the derivation file name of the given operating system without
9046 @item --image-size=@var{size}
9047 For the @code{vm-image} and @code{disk-image} actions, create an image
9048 of the given @var{size}. @var{size} may be a number of bytes, or it may
9049 include a unit as a suffix (@pxref{Block size, size specifications,,
9050 coreutils, GNU Coreutils}).
9052 @item --on-error=@var{strategy}
9053 Apply @var{strategy} when an error occurs when reading @var{file}.
9054 @var{strategy} may be one of the following:
9057 @item nothing-special
9058 Report the error concisely and exit. This is the default strategy.
9061 Likewise, but also display a backtrace.
9064 Report the error and enter Guile's debugger. From there, you can run
9065 commands such as @code{,bt} to get a backtrace, @code{,locals} to
9066 display local variable values, and more generally inspect the program's
9067 state. @xref{Debug Commands,,, guile, GNU Guile Reference Manual}, for
9068 a list of available debugging commands.
9072 Note that all the actions above, except @code{build} and @code{init},
9073 rely on KVM support in the Linux-Libre kernel. Specifically, the
9074 machine should have hardware virtualization support, the corresponding
9075 KVM kernel module should be loaded, and the @file{/dev/kvm} device node
9076 must exist and be readable and writable by the user and by the daemon's
9079 Once you have built, configured, re-configured, and re-re-configured
9080 your GuixSD installation, you may find it useful to list the operating
9081 system generations available on disk---and that you can choose from the
9086 @item list-generations
9087 List a summary of each generation of the operating system available on
9088 disk, in a human-readable way. This is similar to the
9089 @option{--list-generations} option of @command{guix package}
9090 (@pxref{Invoking guix package}).
9092 Optionally, one can specify a pattern, with the same syntax that is used
9093 in @command{guix package --list-generations}, to restrict the list of
9094 generations displayed. For instance, the following command displays
9095 generations up to 10-day old:
9098 $ guix system list-generations 10d
9103 The @command{guix system} command has even more to offer! The following
9104 sub-commands allow you to visualize how your system services relate to
9107 @anchor{system-extension-graph}
9110 @item extension-graph
9111 Emit in Dot/Graphviz format to standard output the @dfn{service
9112 extension graph} of the operating system defined in @var{file}
9113 (@pxref{Service Composition}, for more information on service
9119 $ guix system extension-graph @var{file} | dot -Tpdf > services.pdf
9122 produces a PDF file showing the extension relations among services.
9124 @anchor{system-dmd-graph}
9126 Emit in Dot/Graphviz format to standard output the @dfn{dependency
9127 graph} of dmd services of the operating system defined in @var{file}.
9128 @xref{dmd Services}, for more information and for an example graph.
9133 @node Defining Services
9134 @subsection Defining Services
9136 The previous sections show the available services and how one can combine
9137 them in an @code{operating-system} declaration. But how do we define
9138 them in the first place? And what is a service anyway?
9141 * Service Composition:: The model for composing services.
9142 * Service Types and Services:: Types and services.
9143 * Service Reference:: API reference.
9144 * dmd Services:: A particular type of service.
9147 @node Service Composition
9148 @subsubsection Service Composition
9152 Here we define a @dfn{service} as, broadly, something that extends the
9153 operating system's functionality. Often a service is a process---a
9154 @dfn{daemon}---started when the system boots: a secure shell server, a
9155 Web server, the Guix build daemon, etc. Sometimes a service is a daemon
9156 whose execution can be triggered by another daemon---e.g., an FTP server
9157 started by @command{inetd} or a D-Bus service activated by
9158 @command{dbus-daemon}. Occasionally, a service does not map to a
9159 daemon. For instance, the ``account'' service collects user accounts
9160 and makes sure they exist when the system runs; the ``udev'' service
9161 collects device management rules and makes them available to the eudev
9162 daemon; the @file{/etc} service populates the system's @file{/etc}
9165 @cindex service extensions
9166 GuixSD services are connected by @dfn{extensions}. For instance, the
9167 secure shell service @emph{extends} dmd---GuixSD's initialization system,
9168 running as PID@tie{}1---by giving it the command lines to start and stop
9169 the secure shell daemon (@pxref{Networking Services,
9170 @code{lsh-service}}); the UPower service extends the D-Bus service by
9171 passing it its @file{.service} specification, and extends the udev
9172 service by passing it device management rules (@pxref{Desktop Services,
9173 @code{upower-service}}); the Guix daemon service extends dmd by passing
9174 it the command lines to start and stop the daemon, and extends the
9175 account service by passing it a list of required build user accounts
9176 (@pxref{Base Services}).
9178 All in all, services and their ``extends'' relations form a directed
9179 acyclic graph (DAG). If we represent services as boxes and extensions
9180 as arrows, a typical system might provide something like this:
9182 @image{images/service-graph,,5in,Typical service extension graph.}
9184 @cindex system service
9185 At the bottom, we see the @dfn{system service}, which produces the
9186 directory containing everything to run and boot the system, as returned
9187 by the @command{guix system build} command. @xref{Service Reference},
9188 to learn about the other service types shown here.
9189 @xref{system-extension-graph, the @command{guix system extension-graph}
9190 command}, for information on how to generate this representation for a
9191 particular operating system definition.
9193 @cindex service types
9194 Technically, developers can define @dfn{service types} to express these
9195 relations. There can be any number of services of a given type on the
9196 system---for instance, a system running two instances of the GNU secure
9197 shell server (lsh) has two instances of @var{lsh-service-type}, with
9198 different parameters.
9200 The following section describes the programming interface for service
9203 @node Service Types and Services
9204 @subsubsection Service Types and Services
9206 A @dfn{service type} is a node in the DAG described above. Let us start
9207 with a simple example, the service type for the Guix build daemon
9208 (@pxref{Invoking guix-daemon}):
9211 (define guix-service-type
9215 (list (service-extension dmd-root-service-type guix-dmd-service)
9216 (service-extension account-service-type guix-accounts)
9217 (service-extension activation-service-type guix-activation)))))
9221 It defines a two things:
9225 A name, whose sole purpose is to make inspection and debugging easier.
9228 A list of @dfn{service extensions}, where each extension designates the
9229 target service type and a procedure that, given the service's
9230 parameters, returns a list of object to extend the service of that type.
9232 Every service type has at least one service extension. The only
9233 exception is the @dfn{boot service type}, which is the ultimate service.
9236 In this example, @var{guix-service-type} extends three services:
9239 @item dmd-root-service-type
9240 The @var{guix-dmd-service} procedure defines how the dmd service is
9241 extended. Namely, it returns a @code{<dmd-service>} object that defines
9242 how @command{guix-daemon} is started and stopped (@pxref{dmd Services}).
9244 @item account-service-type
9245 This extension for this service is computed by @var{guix-accounts},
9246 which returns a list of @code{user-group} and @code{user-account}
9247 objects representing the build user accounts (@pxref{Invoking
9250 @item activation-service-type
9251 Here @var{guix-activation} is a procedure that returns a gexp, which is
9252 a code snippet to run at ``activation time''---e.g., when the service is
9256 A service of this type is instantiated like this:
9259 (service guix-service-type
9262 (use-substitutes? #f)))
9265 The second argument to the @code{service} form is a value representing
9266 the parameters of this specific service instance.
9267 @xref{guix-configuration-type, @code{guix-configuration}}, for
9268 information about the @code{guix-configuration} data type.
9270 @var{guix-service-type} is quite simple because it extends other
9271 services but is not extensible itself.
9273 @c @subsubsubsection Extensible Service Types
9275 The service type for an @emph{extensible} service looks like this:
9278 (define udev-service-type
9279 (service-type (name 'udev)
9281 (list (service-extension dmd-root-service-type
9284 (compose concatenate) ;concatenate the list of rules
9285 (extend (lambda (config rules)
9287 (($ <udev-configuration> udev initial-rules)
9289 (udev udev) ;the udev package to use
9290 (rules (append initial-rules rules)))))))))
9293 This is the service type for the
9294 @uref{https://wiki.gentoo.org/wiki/Project:Eudev, eudev device
9295 management daemon}. Compared to the previous example, in addition to an
9296 extension of @var{dmd-root-service-type}, we see two new fields:
9300 This is the procedure to @dfn{compose} the list of extensions to
9301 services of this type.
9303 Services can extend the udev service by passing it lists of rules; we
9304 compose those extensions simply by concatenating them.
9307 This procedure defines how the service's value is @dfn{extended} with
9308 the composition of the extensions.
9310 Udev extensions are composed into a list of rules, but the udev service
9311 value is itself a @code{<udev-configuration>} record. So here, we
9312 extend that record by appending the list of rules is contains to the
9313 list of contributed rules.
9316 There can be only one instance of an extensible service type such as
9317 @var{udev-service-type}. If there were more, the
9318 @code{service-extension} specifications would be ambiguous.
9320 Still here? The next section provides a reference of the programming
9321 interface for services.
9323 @node Service Reference
9324 @subsubsection Service Reference
9326 We have seen an overview of service types (@pxref{Service Types and
9327 Services}). This section provides a reference on how to manipulate
9328 services and service types. This interface is provided by the
9329 @code{(gnu services)} module.
9331 @deffn {Scheme Procedure} service @var{type} @var{value}
9332 Return a new service of @var{type}, a @code{<service-type>} object (see
9333 below.) @var{value} can be any object; it represents the parameters of
9334 this particular service instance.
9337 @deffn {Scheme Procedure} service? @var{obj}
9338 Return true if @var{obj} is a service.
9341 @deffn {Scheme Procedure} service-kind @var{service}
9342 Return the type of @var{service}---i.e., a @code{<service-type>} object.
9345 @deffn {Scheme Procedure} service-parameters @var{service}
9346 Return the value associated with @var{service}. It represents its
9350 Here is an example of how a service is created and manipulated:
9354 (service nginx-service-type
9355 (nginx-configuration
9357 (log-directory log-directory)
9358 (run-directory run-directory)
9359 (file config-file))))
9364 (eq? (service-kind s) nginx-service-type)
9368 The @code{modify-services} form provides a handy way to change the
9369 parameters of some of the services of a list such as
9370 @var{%base-services} (@pxref{Base Services, @code{%base-services}}). Of
9371 course, you could always use standard list combinators such as
9372 @code{map} and @code{fold} to do that (@pxref{SRFI-1, List Library,,
9373 guile, GNU Guile Reference Manual}); @code{modify-services} simply
9374 provides a more concise form for this common pattern.
9376 @deffn {Scheme Syntax} modify-services @var{services} @
9377 (@var{type} @var{variable} => @var{body}) @dots{}
9379 Modify the services listed in @var{services} according to the given
9380 clauses. Each clause has the form:
9383 (@var{type} @var{variable} => @var{body})
9386 where @var{type} is a service type, such as @var{guix-service-type}, and
9387 @var{variable} is an identifier that is bound within @var{body} to the
9388 value of the service of that @var{type}. @xref{Using the Configuration
9389 System}, for an example.
9391 This is a shorthand for:
9394 (map (lambda (service) @dots{}) @var{services})
9398 Next comes the programming interface for service types. This is
9399 something you want to know when writing new service definitions, but not
9400 necessarily when simply looking for ways to customize your
9401 @code{operating-system} declaration.
9403 @deftp {Data Type} service-type
9404 @cindex service type
9405 This is the representation of a @dfn{service type} (@pxref{Service Types
9410 This is a symbol, used only to simplify inspection and debugging.
9412 @item @code{extensions}
9413 A non-empty list of @code{<service-extension>} objects (see below.)
9415 @item @code{compose} (default: @code{#f})
9416 If this is @code{#f}, then the service type denotes services that cannot
9417 be extended---i.e., services that do not receive ``values'' from other
9420 Otherwise, it must be a one-argument procedure. The procedure is called
9421 by @code{fold-services} and is passed a list of values collected from
9422 extensions. It must return a value that is a valid parameter value for
9423 the service instance.
9425 @item @code{extend} (default: @code{#f})
9426 If this is @code{#f}, services of this type cannot be extended.
9428 Otherwise, it must be a two-argument procedure: @code{fold-services}
9429 calls it, passing it the service's initial value as the first argument
9430 and the result of applying @code{compose} to the extension values as the
9434 @xref{Service Types and Services}, for examples.
9437 @deffn {Scheme Procedure} service-extension @var{target-type} @
9439 Return a new extension for services of type @var{target-type}.
9440 @var{compute} must be a one-argument procedure: @code{fold-services}
9441 calls it, passing it the value associated with the service that provides
9442 the extension; it must return a valid value for the target service.
9445 @deffn {Scheme Procedure} service-extension? @var{obj}
9446 Return true if @var{obj} is a service extension.
9449 At the core of the service abstraction lies the @code{fold-services}
9450 procedure, which is responsible for ``compiling'' a list of services
9451 down to a single directory that contains everything needed to boot and
9452 run the system---the directory shown by the @command{guix system build}
9453 command (@pxref{Invoking guix system}). In essence, it propagates
9454 service extensions down the service graph, updating each node parameters
9455 on the way, until it reaches the root node.
9457 @deffn {Scheme Procedure} fold-services @var{services} @
9458 [#:target-type @var{system-service-type}]
9459 Fold @var{services} by propagating their extensions down to the root of
9460 type @var{target-type}; return the root service adjusted accordingly.
9463 Lastly, the @code{(gnu services)} module also defines several essential
9464 service types, some of which are listed below.
9466 @defvr {Scheme Variable} system-service-type
9467 This is the root of the service graph. It produces the system directory
9468 as returned by the @command{guix system build} command.
9471 @defvr {Scheme Variable} boot-service-type
9472 The type of the ``boot service'', which produces the @dfn{boot script}.
9473 The boot script is what the initial RAM disk runs when booting.
9476 @defvr {Scheme Variable} etc-service-type
9477 The type of the @file{/etc} service. This service can be extended by
9478 passing it name/file tuples such as:
9481 (list `("issue" ,(plain-file "issue" "Welcome!\n")))
9484 In this example, the effect would be to add an @file{/etc/issue} file
9485 pointing to the given file.
9488 @defvr {Scheme Variable} setuid-program-service-type
9489 Type for the ``setuid-program service''. This service collects lists of
9490 executable file names, passed as gexps, and adds them to the set of
9491 setuid-root programs on the system (@pxref{Setuid Programs}).
9494 @defvr {Scheme Variable} profile-service-type
9495 Type of the service that populates the @dfn{system profile}---i.e., the
9496 programs under @file{/run/current-system/profile}. Other services can
9497 extend it by passing it lists of packages to add to the system profile.
9502 @subsubsection dmd Services
9506 The @code{(gnu services dmd)} provides a way to define services managed
9507 by GNU@tie{}dmd, which is GuixSD initialization system---the first
9508 process that is started when the system boots, aka. PID@tie{}1
9509 (@pxref{Introduction,,, dmd, GNU dmd Manual}).
9511 Services in dmd can depend on each other. For instance, the SSH daemon
9512 may need to be started after the syslog daemon has been started, which
9513 in turn can only happen once all the file systems have been mounted.
9514 The simple operating system defined earlier (@pxref{Using the
9515 Configuration System}) results in a service graph like this:
9517 @image{images/dmd-graph,,5in,Typical dmd service graph.}
9519 You can actually generate such a graph for any operating system
9520 definition using the @command{guix system dmd-graph} command
9521 (@pxref{system-dmd-graph, @command{guix system dmd-graph}}).
9523 The @var{%dmd-root-service} is a service object representing PID@tie{}1,
9524 of type @var{dmd-root-service-type}; it can be extended by passing it
9525 lists of @code{<dmd-service>} objects.
9527 @deftp {Data Type} dmd-service
9528 The data type representing a service managed by dmd.
9531 @item @code{provision}
9532 This is a list of symbols denoting what the service provides.
9534 These are the names that may be passed to @command{deco start},
9535 @command{deco status}, and similar commands (@pxref{Invoking deco,,,
9536 dmd, GNU dmd Manual}). @xref{Slots of services, the @code{provides}
9537 slot,, dmd, GNU dmd Manual}, for details.
9539 @item @code{requirements} (default: @code{'()})
9540 List of symbols denoting the dmd services this one depends on.
9542 @item @code{respawn?} (default: @code{#t})
9543 Whether to restart the service when it stops, for instance when the
9544 underlying process dies.
9547 @itemx @code{stop} (default: @code{#~(const #f)})
9548 The @code{start} and @code{stop} fields refer to dmd's facilities to
9549 start and stop processes (@pxref{Service De- and Constructors,,, dmd,
9550 GNU dmd Manual}). They are given as G-expressions that get expanded in
9551 the dmd configuration file (@pxref{G-Expressions}).
9553 @item @code{documentation}
9554 A documentation string, as shown when running:
9557 deco doc @var{service-name}
9560 where @var{service-name} is one of the symbols in @var{provision}
9561 (@pxref{Invoking deco,,, dmd, GNU dmd Manual}).
9563 @item @code{modules} (default: @var{%default-modules})
9564 This is the list of modules that must be in scope when @code{start} and
9565 @code{stop} are evaluated.
9567 @item @code{imported-modules} (default: @var{%default-imported-modules})
9568 This is the list of modules to import in the execution environment of
9574 @defvr {Scheme Variable} dmd-root-service-type
9575 The service type for the dmd ``root service''---i.e., PID@tie{}1.
9577 This is the service type that extensions target when they want to create
9578 dmd services (@pxref{Service Types and Services}, for an example). Each
9579 extension must pass a list of @code{<dmd-service>}.
9582 @defvr {Scheme Variable} %dmd-root-service
9583 This service represents PID@tie{}1.
9587 @node Installing Debugging Files
9588 @section Installing Debugging Files
9590 @cindex debugging files
9591 Program binaries, as produced by the GCC compilers for instance, are
9592 typically written in the ELF format, with a section containing
9593 @dfn{debugging information}. Debugging information is what allows the
9594 debugger, GDB, to map binary code to source code; it is required to
9595 debug a compiled program in good conditions.
9597 The problem with debugging information is that is takes up a fair amount
9598 of disk space. For example, debugging information for the GNU C Library
9599 weighs in at more than 60 MiB. Thus, as a user, keeping all the
9600 debugging info of all the installed programs is usually not an option.
9601 Yet, space savings should not come at the cost of an impediment to
9602 debugging---especially in the GNU system, which should make it easier
9603 for users to exert their computing freedom (@pxref{GNU Distribution}).
9605 Thankfully, the GNU Binary Utilities (Binutils) and GDB provide a
9606 mechanism that allows users to get the best of both worlds: debugging
9607 information can be stripped from the binaries and stored in separate
9608 files. GDB is then able to load debugging information from those files,
9609 when they are available (@pxref{Separate Debug Files,,, gdb, Debugging
9612 The GNU distribution takes advantage of this by storing debugging
9613 information in the @code{lib/debug} sub-directory of a separate package
9614 output unimaginatively called @code{debug} (@pxref{Packages with
9615 Multiple Outputs}). Users can choose to install the @code{debug} output
9616 of a package when they need it. For instance, the following command
9617 installs the debugging information for the GNU C Library and for GNU
9621 guix package -i glibc:debug guile:debug
9624 GDB must then be told to look for debug files in the user's profile, by
9625 setting the @code{debug-file-directory} variable (consider setting it
9626 from the @file{~/.gdbinit} file, @pxref{Startup,,, gdb, Debugging with
9630 (gdb) set debug-file-directory ~/.guix-profile/lib/debug
9633 From there on, GDB will pick up debugging information from the
9634 @code{.debug} files under @file{~/.guix-profile/lib/debug}.
9636 In addition, you will most likely want GDB to be able to show the source
9637 code being debugged. To do that, you will have to unpack the source
9638 code of the package of interest (obtained with @code{guix build
9639 --source}, @pxref{Invoking guix build}), and to point GDB to that source
9640 directory using the @code{directory} command (@pxref{Source Path,
9641 @code{directory},, gdb, Debugging with GDB}).
9643 @c XXX: keep me up-to-date
9644 The @code{debug} output mechanism in Guix is implemented by the
9645 @code{gnu-build-system} (@pxref{Build Systems}). Currently, it is
9646 opt-in---debugging information is available only for those packages
9647 whose definition explicitly declares a @code{debug} output. This may be
9648 changed to opt-out in the future, if our build farm servers can handle
9649 the load. To check whether a package has a @code{debug} output, use
9650 @command{guix package --list-available} (@pxref{Invoking guix package}).
9653 @node Security Updates
9654 @section Security Updates
9657 As of version @value{VERSION}, the feature described in this section is
9661 @cindex security updates
9662 Occasionally, important security vulnerabilities are discovered in core
9663 software packages and must be patched. Guix follows a functional
9664 package management discipline (@pxref{Introduction}), which implies
9665 that, when a package is changed, @emph{every package that depends on it}
9666 must be rebuilt. This can significantly slow down the deployment of
9667 fixes in core packages such as libc or Bash, since basically the whole
9668 distribution would need to be rebuilt. Using pre-built binaries helps
9669 (@pxref{Substitutes}), but deployment may still take more time than
9673 To address that, Guix implements @dfn{grafts}, a mechanism that allows
9674 for fast deployment of critical updates without the costs associated
9675 with a whole-distribution rebuild. The idea is to rebuild only the
9676 package that needs to be patched, and then to ``graft'' it onto packages
9677 explicitly installed by the user and that were previously referring to
9678 the original package. The cost of grafting is typically very low, and
9679 order of magnitudes lower than a full rebuild of the dependency chain.
9681 @cindex replacements of packages, for grafts
9682 For instance, suppose a security update needs to be applied to Bash.
9683 Guix developers will provide a package definition for the ``fixed''
9684 Bash, say @var{bash-fixed}, in the usual way (@pxref{Defining
9685 Packages}). Then, the original package definition is augmented with a
9686 @code{replacement} field pointing to the package containing the bug fix:
9693 (replacement bash-fixed)))
9696 From there on, any package depending directly or indirectly on Bash that
9697 is installed will automatically be ``rewritten'' to refer to
9698 @var{bash-fixed} instead of @var{bash}. This grafting process takes
9699 time proportional to the size of the package, but expect less than a
9700 minute for an ``average'' package on a recent machine.
9702 Currently, the graft and the package it replaces (@var{bash-fixed} and
9703 @var{bash} in the example above) must have the exact same @code{name}
9704 and @code{version} fields. This restriction mostly comes from the fact
9705 that grafting works by patching files, including binary files, directly.
9706 Other restrictions may apply: for instance, when adding a graft to a
9707 package providing a shared library, the original shared library and its
9708 replacement must have the same @code{SONAME} and be binary-compatible.
9711 @node Package Modules
9712 @section Package Modules
9714 From a programming viewpoint, the package definitions of the
9715 GNU distribution are provided by Guile modules in the @code{(gnu packages
9716 @dots{})} name space@footnote{Note that packages under the @code{(gnu
9717 packages @dots{})} module name space are not necessarily ``GNU
9718 packages''. This module naming scheme follows the usual Guile module
9719 naming convention: @code{gnu} means that these modules are distributed
9720 as part of the GNU system, and @code{packages} identifies modules that
9721 define packages.} (@pxref{Modules, Guile modules,, guile, GNU Guile
9722 Reference Manual}). For instance, the @code{(gnu packages emacs)}
9723 module exports a variable named @code{emacs}, which is bound to a
9724 @code{<package>} object (@pxref{Defining Packages}).
9726 The @code{(gnu packages @dots{})} module name space is
9727 automatically scanned for packages by the command-line tools. For
9728 instance, when running @code{guix package -i emacs}, all the @code{(gnu
9729 packages @dots{})} modules are scanned until one that exports a package
9730 object whose name is @code{emacs} is found. This package search
9731 facility is implemented in the @code{(gnu packages)} module.
9733 @cindex customization, of packages
9734 @cindex package module search path
9735 Users can store package definitions in modules with different
9736 names---e.g., @code{(my-packages emacs)}@footnote{Note that the file
9737 name and module name must match. For instance, the @code{(my-packages
9738 emacs)} module must be stored in a @file{my-packages/emacs.scm} file
9739 relative to the load path specified with @option{--load-path} or
9740 @code{GUIX_PACKAGE_PATH}. @xref{Modules and the File System,,,
9741 guile, GNU Guile Reference Manual}, for details.}. These package definitions
9742 will not be visible by default. Thus, users can invoke commands such as
9743 @command{guix package} and @command{guix build} have to be used with the
9744 @code{-e} option so that they know where to find the package. Better
9745 yet, they can use the
9746 @code{-L} option of these commands to make those modules visible
9747 (@pxref{Invoking guix build, @code{--load-path}}), or define the
9748 @code{GUIX_PACKAGE_PATH} environment variable. This environment
9749 variable makes it easy to extend or customize the distribution and is
9750 honored by all the user interfaces.
9752 @defvr {Environment Variable} GUIX_PACKAGE_PATH
9753 This is a colon-separated list of directories to search for package
9754 modules. Directories listed in this variable take precedence over the
9755 distribution's own modules.
9758 The distribution is fully @dfn{bootstrapped} and @dfn{self-contained}:
9759 each package is built based solely on other packages in the
9760 distribution. The root of this dependency graph is a small set of
9761 @dfn{bootstrap binaries}, provided by the @code{(gnu packages
9762 bootstrap)} module. For more information on bootstrapping,
9763 @pxref{Bootstrapping}.
9765 @node Packaging Guidelines
9766 @section Packaging Guidelines
9768 The GNU distribution is nascent and may well lack some of your favorite
9769 packages. This section describes how you can help make the distribution
9770 grow. @xref{Contributing}, for additional information on how you can
9773 Free software packages are usually distributed in the form of
9774 @dfn{source code tarballs}---typically @file{tar.gz} files that contain
9775 all the source files. Adding a package to the distribution means
9776 essentially two things: adding a @dfn{recipe} that describes how to
9777 build the package, including a list of other packages required to build
9778 it, and adding @dfn{package meta-data} along with that recipe, such as a
9779 description and licensing information.
9781 In Guix all this information is embodied in @dfn{package definitions}.
9782 Package definitions provide a high-level view of the package. They are
9783 written using the syntax of the Scheme programming language; in fact,
9784 for each package we define a variable bound to the package definition,
9785 and export that variable from a module (@pxref{Package Modules}).
9786 However, in-depth Scheme knowledge is @emph{not} a prerequisite for
9787 creating packages. For more information on package definitions,
9788 @pxref{Defining Packages}.
9790 Once a package definition is in place, stored in a file in the Guix
9791 source tree, it can be tested using the @command{guix build} command
9792 (@pxref{Invoking guix build}). For example, assuming the new package is
9793 called @code{gnew}, you may run this command from the Guix build tree
9794 (@pxref{Running Guix Before It Is Installed}):
9797 ./pre-inst-env guix build gnew --keep-failed
9800 Using @code{--keep-failed} makes it easier to debug build failures since
9801 it provides access to the failed build tree. Another useful
9802 command-line option when debugging is @code{--log-file}, to access the
9805 If the package is unknown to the @command{guix} command, it may be that
9806 the source file contains a syntax error, or lacks a @code{define-public}
9807 clause to export the package variable. To figure it out, you may load
9808 the module from Guile to get more information about the actual error:
9811 ./pre-inst-env guile -c '(use-modules (gnu packages gnew))'
9814 Once your package builds correctly, please send us a patch
9815 (@pxref{Contributing}). Well, if you need help, we will be happy to
9816 help you too. Once the patch is committed in the Guix repository, the
9817 new package automatically gets built on the supported platforms by
9818 @url{http://hydra.gnu.org/jobset/gnu/master, our continuous integration
9822 Users can obtain the new package definition simply by running
9823 @command{guix pull} (@pxref{Invoking guix pull}). When
9824 @code{hydra.gnu.org} is done building the package, installing the
9825 package automatically downloads binaries from there
9826 (@pxref{Substitutes}). The only place where human intervention is
9827 needed is to review and apply the patch.
9831 * Software Freedom:: What may go into the distribution.
9832 * Package Naming:: What's in a name?
9833 * Version Numbers:: When the name is not enough.
9834 * Synopses and Descriptions:: Helping users find the right package.
9835 * Python Modules:: Taming the snake.
9836 * Perl Modules:: Little pearls.
9837 * Fonts:: Fond of fonts.
9840 @node Software Freedom
9841 @subsection Software Freedom
9843 @c Adapted from http://www.gnu.org/philosophy/philosophy.html.
9845 The GNU operating system has been developed so that users can have
9846 freedom in their computing. GNU is @dfn{free software}, meaning that
9847 users have the @url{http://www.gnu.org/philosophy/free-sw.html,four
9848 essential freedoms}: to run the program, to study and change the program
9849 in source code form, to redistribute exact copies, and to distribute
9850 modified versions. Packages found in the GNU distribution provide only
9851 software that conveys these four freedoms.
9853 In addition, the GNU distribution follow the
9854 @url{http://www.gnu.org/distros/free-system-distribution-guidelines.html,free
9855 software distribution guidelines}. Among other things, these guidelines
9856 reject non-free firmware, recommendations of non-free software, and
9857 discuss ways to deal with trademarks and patents.
9859 Some packages contain a small and optional subset that violates the
9860 above guidelines, for instance because this subset is itself non-free
9861 code. When that happens, the offending items are removed with
9862 appropriate patches or code snippets in the package definition's
9863 @code{origin} form (@pxref{Defining Packages}). That way, @code{guix
9864 build --source} returns the ``freed'' source rather than the unmodified
9868 @node Package Naming
9869 @subsection Package Naming
9871 A package has actually two names associated with it:
9872 First, there is the name of the @emph{Scheme variable}, the one following
9873 @code{define-public}. By this name, the package can be made known in the
9874 Scheme code, for instance as input to another package. Second, there is
9875 the string in the @code{name} field of a package definition. This name
9876 is used by package management commands such as
9877 @command{guix package} and @command{guix build}.
9879 Both are usually the same and correspond to the lowercase conversion of
9880 the project name chosen upstream, with underscores replaced with
9881 hyphens. For instance, GNUnet is available as @code{gnunet}, and
9882 SDL_net as @code{sdl-net}.
9884 We do not add @code{lib} prefixes for library packages, unless these are
9885 already part of the official project name. But @pxref{Python
9886 Modules} and @ref{Perl Modules} for special rules concerning modules for
9887 the Python and Perl languages.
9889 Font package names are handled differently, @pxref{Fonts}.
9892 @node Version Numbers
9893 @subsection Version Numbers
9895 We usually package only the latest version of a given free software
9896 project. But sometimes, for instance for incompatible library versions,
9897 two (or more) versions of the same package are needed. These require
9898 different Scheme variable names. We use the name as defined
9899 in @ref{Package Naming}
9900 for the most recent version; previous versions use the same name, suffixed
9901 by @code{-} and the smallest prefix of the version number that may
9902 distinguish the two versions.
9904 The name inside the package definition is the same for all versions of a
9905 package and does not contain any version number.
9907 For instance, the versions 2.24.20 and 3.9.12 of GTK+ may be packaged as follows:
9915 (define-public gtk+-2
9921 If we also wanted GTK+ 3.8.2, this would be packaged as
9923 (define-public gtk+-3.8
9930 @node Synopses and Descriptions
9931 @subsection Synopses and Descriptions
9933 As we have seen before, each package in GNU@tie{}Guix includes a
9934 synopsis and a description (@pxref{Defining Packages}). Synopses and
9935 descriptions are important: They are what @command{guix package
9936 --search} searches, and a crucial piece of information to help users
9937 determine whether a given package suits their needs. Consequently,
9938 packagers should pay attention to what goes into them.
9940 Synopses must start with a capital letter and must not end with a
9941 period. They must not start with ``a'' or ``the'', which usually does
9942 not bring anything; for instance, prefer ``File-frobbing tool'' over ``A
9943 tool that frobs files''. The synopsis should say what the package
9944 is---e.g., ``Core GNU utilities (file, text, shell)''---or what it is
9945 used for---e.g., the synopsis for GNU@tie{}grep is ``Print lines
9946 matching a pattern''.
9948 Keep in mind that the synopsis must be meaningful for a very wide
9949 audience. For example, ``Manipulate alignments in the SAM format''
9950 might make sense for a seasoned bioinformatics researcher, but might be
9951 fairly unhelpful or even misleading to a non-specialized audience. It
9952 is a good idea to come up with a synopsis that gives an idea of the
9953 application domain of the package. In this example, this might give
9954 something like ``Manipulate nucleotide sequence alignments'', which
9955 hopefully gives the user a better idea of whether this is what they are
9958 @cindex Texinfo markup, in package descriptions
9959 Descriptions should take between five and ten lines. Use full
9960 sentences, and avoid using acronyms without first introducing them.
9961 Descriptions can include Texinfo markup, which is useful to introduce
9962 ornaments such as @code{@@code} or @code{@@dfn}, bullet lists, or
9963 hyperlinks (@pxref{Overview,,, texinfo, GNU Texinfo}). However you
9964 should be careful when using some characters for example @samp{@@} and
9965 curly braces which are the basic special characters in Texinfo
9966 (@pxref{Special Characters,,, texinfo, GNU Texinfo}). User interfaces
9967 such as @command{guix package --show} take care of rendering it
9970 Synopses and descriptions are translated by volunteers
9971 @uref{http://translationproject.org/domain/guix-packages.html, at the
9972 Translation Project} so that as many users as possible can read them in
9973 their native language. User interfaces search them and display them in
9974 the language specified by the current locale.
9976 Translation is a lot of work so, as a packager, please pay even more
9977 attention to your synopses and descriptions as every change may entail
9978 additional work for translators. In order to help them, it is possible
9979 to make recommendations or instructions visible to them by inserting
9980 special comments like this (@pxref{xgettext Invocation,,, gettext, GNU
9984 ;; TRANSLATORS: "X11 resize-and-rotate" should not be translated.
9985 (description "ARandR is designed to provide a simple visual front end
9986 for the X11 resize-and-rotate (RandR) extension. @dots{}")
9990 @node Python Modules
9991 @subsection Python Modules
9993 We currently package Python 2 and Python 3, under the Scheme variable names
9994 @code{python-2} and @code{python} as explained in @ref{Version Numbers}.
9995 To avoid confusion and naming clashes with other programming languages, it
9996 seems desirable that the name of a package for a Python module contains
9997 the word @code{python}.
9999 Some modules are compatible with only one version of Python, others with both.
10000 If the package Foo compiles only with Python 3, we name it
10001 @code{python-foo}; if it compiles only with Python 2, we name it
10002 @code{python2-foo}. If it is compatible with both versions, we create two
10003 packages with the corresponding names.
10005 If a project already contains the word @code{python}, we drop this;
10006 for instance, the module python-dateutil is packaged under the names
10007 @code{python-dateutil} and @code{python2-dateutil}.
10011 @subsection Perl Modules
10013 Perl programs standing for themselves are named as any other package,
10014 using the lowercase upstream name.
10015 For Perl packages containing a single class, we use the lowercase class name,
10016 replace all occurrences of @code{::} by dashes and prepend the prefix
10018 So the class @code{XML::Parser} becomes @code{perl-xml-parser}.
10019 Modules containing several classes keep their lowercase upstream name and
10020 are also prepended by @code{perl-}. Such modules tend to have the word
10021 @code{perl} somewhere in their name, which gets dropped in favor of the
10022 prefix. For instance, @code{libwww-perl} becomes @code{perl-libwww}.
10028 For fonts that are in general not installed by a user for typesetting
10029 purposes, or that are distributed as part of a larger software package,
10030 we rely on the general packaging rules for software; for instance, this
10031 applies to the fonts delivered as part of the X.Org system or fonts that
10032 are part of TeX Live.
10034 To make it easier for a user to search for fonts, names for other packages
10035 containing only fonts are constructed as follows, independently of the
10036 upstream package name.
10038 The name of a package containing only one font family starts with
10039 @code{font-}; it is followed by the foundry name and a dash @code{-}
10040 if the foundry is known, and the font family name, in which spaces are
10041 replaced by dashes (and as usual, all upper case letters are transformed
10043 For example, the Gentium font family by SIL is packaged under the name
10044 @code{font-sil-gentium}.
10046 For a package containing several font families, the name of the collection
10047 is used in the place of the font family name.
10048 For instance, the Liberation fonts consist of three families,
10049 Liberation Sans, Liberation Serif and Liberation Mono.
10050 These could be packaged separately under the names
10051 @code{font-liberation-sans} and so on; but as they are distributed together
10052 under a common name, we prefer to package them together as
10053 @code{font-liberation}.
10055 In the case where several formats of the same font family or font collection
10056 are packaged separately, a short form of the format, prepended by a dash,
10057 is added to the package name. We use @code{-ttf} for TrueType fonts,
10058 @code{-otf} for OpenType fonts and @code{-type1} for PostScript Type 1
10063 @node Bootstrapping
10064 @section Bootstrapping
10066 @c Adapted from the ELS 2013 paper.
10068 @cindex bootstrapping
10070 Bootstrapping in our context refers to how the distribution gets built
10071 ``from nothing''. Remember that the build environment of a derivation
10072 contains nothing but its declared inputs (@pxref{Introduction}). So
10073 there's an obvious chicken-and-egg problem: how does the first package
10074 get built? How does the first compiler get compiled? Note that this is
10075 a question of interest only to the curious hacker, not to the regular
10076 user, so you can shamelessly skip this section if you consider yourself
10077 a ``regular user''.
10079 @cindex bootstrap binaries
10080 The GNU system is primarily made of C code, with libc at its core. The
10081 GNU build system itself assumes the availability of a Bourne shell and
10082 command-line tools provided by GNU Coreutils, Awk, Findutils, `sed', and
10083 `grep'. Furthermore, build programs---programs that run
10084 @code{./configure}, @code{make}, etc.---are written in Guile Scheme
10085 (@pxref{Derivations}). Consequently, to be able to build anything at
10086 all, from scratch, Guix relies on pre-built binaries of Guile, GCC,
10087 Binutils, libc, and the other packages mentioned above---the
10088 @dfn{bootstrap binaries}.
10090 These bootstrap binaries are ``taken for granted'', though we can also
10091 re-create them if needed (more on that later).
10093 @unnumberedsubsec Preparing to Use the Bootstrap Binaries
10095 @c As of Emacs 24.3, Info-mode displays the image, but since it's a
10096 @c large image, it's hard to scroll. Oh well.
10097 @image{images/bootstrap-graph,6in,,Dependency graph of the early bootstrap derivations}
10099 The figure above shows the very beginning of the dependency graph of the
10100 distribution, corresponding to the package definitions of the @code{(gnu
10101 packages bootstrap)} module. At this level of detail, things are
10102 slightly complex. First, Guile itself consists of an ELF executable,
10103 along with many source and compiled Scheme files that are dynamically
10104 loaded when it runs. This gets stored in the @file{guile-2.0.7.tar.xz}
10105 tarball shown in this graph. This tarball is part of Guix's ``source''
10106 distribution, and gets inserted into the store with @code{add-to-store}
10107 (@pxref{The Store}).
10109 But how do we write a derivation that unpacks this tarball and adds it
10110 to the store? To solve this problem, the @code{guile-bootstrap-2.0.drv}
10111 derivation---the first one that gets built---uses @code{bash} as its
10112 builder, which runs @code{build-bootstrap-guile.sh}, which in turn calls
10113 @code{tar} to unpack the tarball. Thus, @file{bash}, @file{tar},
10114 @file{xz}, and @file{mkdir} are statically-linked binaries, also part of
10115 the Guix source distribution, whose sole purpose is to allow the Guile
10116 tarball to be unpacked.
10118 Once @code{guile-bootstrap-2.0.drv} is built, we have a functioning
10119 Guile that can be used to run subsequent build programs. Its first task
10120 is to download tarballs containing the other pre-built binaries---this
10121 is what the @code{.tar.xz.drv} derivations do. Guix modules such as
10122 @code{ftp-client.scm} are used for this purpose. The
10123 @code{module-import.drv} derivations import those modules in a directory
10124 in the store, using the original layout. The
10125 @code{module-import-compiled.drv} derivations compile those modules, and
10126 write them in an output directory with the right layout. This
10127 corresponds to the @code{#:modules} argument of
10128 @code{build-expression->derivation} (@pxref{Derivations}).
10130 Finally, the various tarballs are unpacked by the
10131 derivations @code{gcc-bootstrap-0.drv}, @code{glibc-bootstrap-0.drv},
10132 etc., at which point we have a working C tool chain.
10135 @unnumberedsubsec Building the Build Tools
10137 @c TODO: Add a package-level dependency graph generated from (gnu
10140 Bootstrapping is complete when we have a full tool chain that does not
10141 depend on the pre-built bootstrap tools discussed above. This
10142 no-dependency requirement is verified by checking whether the files of
10143 the final tool chain contain references to the @file{/gnu/store}
10144 directories of the bootstrap inputs. The process that leads to this
10145 ``final'' tool chain is described by the package definitions found in
10146 the @code{(gnu packages commencement)} module.
10148 @c See <http://lists.gnu.org/archive/html/gnu-system-discuss/2012-10/msg00000.html>.
10149 The first tool that gets built with the bootstrap binaries is
10150 GNU Make, which is a prerequisite for all the following packages.
10151 From there Findutils and Diffutils get built.
10153 Then come the first-stage Binutils and GCC, built as pseudo cross
10154 tools---i.e., with @code{--target} equal to @code{--host}. They are
10155 used to build libc. Thanks to this cross-build trick, this libc is
10156 guaranteed not to hold any reference to the initial tool chain.
10158 From there the final Binutils and GCC are built. GCC uses @code{ld}
10159 from the final Binutils, and links programs against the just-built libc.
10160 This tool chain is used to build the other packages used by Guix and by
10161 the GNU Build System: Guile, Bash, Coreutils, etc.
10163 And voilà! At this point we have the complete set of build tools that
10164 the GNU Build System expects. These are in the @code{%final-inputs}
10165 variable of the @code{(gnu packages commencement)} module, and are
10166 implicitly used by any package that uses @code{gnu-build-system}
10167 (@pxref{Build Systems, @code{gnu-build-system}}).
10170 @unnumberedsubsec Building the Bootstrap Binaries
10172 Because the final tool chain does not depend on the bootstrap binaries,
10173 those rarely need to be updated. Nevertheless, it is useful to have an
10174 automated way to produce them, should an update occur, and this is what
10175 the @code{(gnu packages make-bootstrap)} module provides.
10177 The following command builds the tarballs containing the bootstrap
10178 binaries (Guile, Binutils, GCC, libc, and a tarball containing a mixture
10179 of Coreutils and other basic command-line tools):
10182 guix build bootstrap-tarballs
10185 The generated tarballs are those that should be referred to in the
10186 @code{(gnu packages bootstrap)} module mentioned at the beginning of
10189 Still here? Then perhaps by now you've started to wonder: when do we
10190 reach a fixed point? That is an interesting question! The answer is
10191 unknown, but if you would like to investigate further (and have
10192 significant computational and storage resources to do so), then let us
10196 @section Porting to a New Platform
10198 As discussed above, the GNU distribution is self-contained, and
10199 self-containment is achieved by relying on pre-built ``bootstrap
10200 binaries'' (@pxref{Bootstrapping}). These binaries are specific to an
10201 operating system kernel, CPU architecture, and application binary
10202 interface (ABI). Thus, to port the distribution to a platform that is
10203 not yet supported, one must build those bootstrap binaries, and update
10204 the @code{(gnu packages bootstrap)} module to use them on that platform.
10206 Fortunately, Guix can @emph{cross compile} those bootstrap binaries.
10207 When everything goes well, and assuming the GNU tool chain supports the
10208 target platform, this can be as simple as running a command like this
10212 guix build --target=armv5tel-linux-gnueabi bootstrap-tarballs
10215 For this to work, the @code{glibc-dynamic-linker} procedure in
10216 @code{(gnu packages bootstrap)} must be augmented to return the right
10217 file name for libc's dynamic linker on that platform; likewise,
10218 @code{system->linux-architecture} in @code{(gnu packages linux)} must be
10219 taught about the new platform.
10221 Once these are built, the @code{(gnu packages bootstrap)} module needs
10222 to be updated to refer to these binaries on the target platform. That
10223 is, the hashes and URLs of the bootstrap tarballs for the new platform
10224 must be added alongside those of the currently supported platforms. The
10225 bootstrap Guile tarball is treated specially: it is expected to be
10226 available locally, and @file{gnu-system.am} has rules do download it for
10227 the supported architectures; a rule for the new platform must be added
10230 In practice, there may be some complications. First, it may be that the
10231 extended GNU triplet that specifies an ABI (like the @code{eabi} suffix
10232 above) is not recognized by all the GNU tools. Typically, glibc
10233 recognizes some of these, whereas GCC uses an extra @code{--with-abi}
10234 configure flag (see @code{gcc.scm} for examples of how to handle this).
10235 Second, some of the required packages could fail to build for that
10236 platform. Lastly, the generated binaries could be broken for some
10239 @c *********************************************************************
10240 @include contributing.texi
10242 @c *********************************************************************
10243 @node Acknowledgments
10244 @chapter Acknowledgments
10246 Guix is based on the @uref{http://nixos.org/nix/, Nix package manager},
10247 which was designed and
10248 implemented by Eelco Dolstra, with contributions from other people (see
10249 the @file{nix/AUTHORS} file in Guix.) Nix pioneered functional package
10250 management, and promoted unprecedented features, such as transactional
10251 package upgrades and rollbacks, per-user profiles, and referentially
10252 transparent build processes. Without this work, Guix would not exist.
10254 The Nix-based software distributions, Nixpkgs and NixOS, have also been
10255 an inspiration for Guix.
10257 GNU@tie{}Guix itself is a collective work with contributions from a
10258 number of people. See the @file{AUTHORS} file in Guix for more
10259 information on these fine people. The @file{THANKS} file lists people
10260 who have helped by reporting bugs, taking care of the infrastructure,
10261 providing artwork and themes, making suggestions, and more---thank you!
10264 @c *********************************************************************
10265 @node GNU Free Documentation License
10266 @appendix GNU Free Documentation License
10268 @include fdl-1.3.texi
10270 @c *********************************************************************
10271 @node Concept Index
10272 @unnumbered Concept Index
10275 @node Programming Index
10276 @unnumbered Programming Index
10277 @syncodeindex tp fn
10278 @syncodeindex vr fn
10283 @c Local Variables:
10284 @c ispell-local-dictionary: "american";