6 @documentencoding UTF-8
7 @settitle GNU Guix Reference Manual
13 Copyright @copyright{} 2012, 2013, 2014, 2015, 2016 Ludovic Courtès@*
14 Copyright @copyright{} 2013, 2014 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@*
19 Copyright @copyright{} 2015, 2016 Leo Famulari
21 Permission is granted to copy, distribute and/or modify this document
22 under the terms of the GNU Free Documentation License, Version 1.3 or
23 any later version published by the Free Software Foundation; with no
24 Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A
25 copy of the license is included in the section entitled ``GNU Free
26 Documentation License''.
29 @dircategory Package management
31 * guix: (guix). Guix, the functional package manager.
32 * guix package: (guix)Invoking guix package
33 Managing packages with Guix.
34 * guix build: (guix)Invoking guix build
35 Building packages with Guix.
36 * guix system: (guix)Invoking guix system
37 Managing the operating system configuration.
40 @dircategory Software development
42 * guix environment: (guix)Invoking guix environment
43 Building development environments with Guix.
47 @title GNU Guix Reference Manual
48 @subtitle Using the GNU Guix Functional Package Manager
49 @author The GNU Guix Developers
52 @vskip 0pt plus 1filll
53 Edition @value{EDITION} @*
61 @c *********************************************************************
65 This document describes GNU Guix version @value{VERSION}, a functional
66 package management tool written for the GNU system.
69 * Introduction:: What is Guix about?
70 * Installation:: Installing Guix.
71 * Package Management:: Package installation, upgrade, etc.
72 * Emacs Interface:: Using Guix from Emacs.
73 * Programming Interface:: Using Guix in Scheme.
74 * Utilities:: Package management commands.
75 * GNU Distribution:: Software for your friendly GNU system.
76 * Contributing:: Your help needed!
78 * Acknowledgments:: Thanks!
79 * GNU Free Documentation License:: The license of this manual.
80 * Concept Index:: Concepts.
81 * Programming Index:: Data types, functions, and variables.
84 --- The Detailed Node Listing ---
88 * Binary Installation:: Getting Guix running in no time!
89 * Requirements:: Software needed to build and run Guix.
90 * Running the Test Suite:: Testing Guix.
91 * Setting Up the Daemon:: Preparing the build daemon's environment.
92 * Invoking guix-daemon:: Running the build daemon.
93 * Application Setup:: Application-specific setup.
97 * Build Environment Setup:: Preparing the isolated build environment.
98 * Daemon Offload Setup:: Offloading builds to remote machines.
102 * Features:: How Guix will make your life brighter.
103 * Invoking guix package:: Package installation, removal, etc.
104 * Substitutes:: Downloading pre-built binaries.
105 * Packages with Multiple Outputs:: Single source package, multiple outputs.
106 * Invoking guix gc:: Running the garbage collector.
107 * Invoking guix pull:: Fetching the latest Guix and distribution.
108 * Invoking guix archive:: Exporting and importing store files.
112 * Initial Setup: Emacs Initial Setup. Preparing @file{~/.emacs}.
113 * Package Management: Emacs Package Management. Managing packages and generations.
114 * Licenses: Emacs Licenses. Interface for licenses of Guix packages.
115 * Popup Interface: Emacs Popup Interface. Magit-like interface for guix commands.
116 * Prettify Mode: Emacs Prettify. Abbreviating @file{/gnu/store/@dots{}} file names.
117 * Build Log Mode: Emacs Build Log. Highlighting Guix build logs.
118 * Completions: Emacs Completions. Completing @command{guix} shell command.
119 * Development: Emacs Development. Tools for Guix developers.
120 * Hydra: Emacs Hydra. Interface for Guix build farm.
122 Programming Interface
124 * Defining Packages:: Defining new packages.
125 * Build Systems:: Specifying how packages are built.
126 * The Store:: Manipulating the package store.
127 * Derivations:: Low-level interface to package derivations.
128 * The Store Monad:: Purely functional interface to the store.
129 * G-Expressions:: Manipulating build expressions.
133 * package Reference:: The package data type.
134 * origin Reference:: The origin data type.
138 * Invoking guix build:: Building packages from the command line.
139 * Invoking guix edit:: Editing package definitions.
140 * Invoking guix download:: Downloading a file and printing its hash.
141 * Invoking guix hash:: Computing the cryptographic hash of a file.
142 * Invoking guix import:: Importing package definitions.
143 * Invoking guix refresh:: Updating package definitions.
144 * Invoking guix lint:: Finding errors in package definitions.
145 * Invoking guix size:: Profiling disk usage.
146 * Invoking guix graph:: Visualizing the graph of packages.
147 * Invoking guix environment:: Setting up development environments.
148 * Invoking guix publish:: Sharing substitutes.
149 * Invoking guix challenge:: Challenging substitute servers.
150 * Invoking guix container:: Process isolation.
154 * System Installation:: Installing the whole operating system.
155 * System Configuration:: Configuring the operating system.
156 * Installing Debugging Files:: Feeding the debugger.
157 * Security Updates:: Deploying security fixes quickly.
158 * Package Modules:: Packages from the programmer's viewpoint.
159 * Packaging Guidelines:: Growing the distribution.
160 * Bootstrapping:: GNU/Linux built from scratch.
161 * Porting:: Targeting another platform or kernel.
165 * Using the Configuration System:: Customizing your GNU system.
166 * operating-system Reference:: Detail of operating-system declarations.
167 * File Systems:: Configuring file system mounts.
168 * Mapped Devices:: Block device extra processing.
169 * User Accounts:: Specifying user accounts.
170 * Locales:: Language and cultural convention settings.
171 * Services:: Specifying system services.
172 * Setuid Programs:: Programs running with root privileges.
173 * X.509 Certificates:: Authenticating HTTPS servers.
174 * Name Service Switch:: Configuring libc's name service switch.
175 * Initial RAM Disk:: Linux-Libre bootstrapping.
176 * GRUB Configuration:: Configuring the boot loader.
177 * Invoking guix system:: Instantiating a system configuration.
178 * Running GuixSD in a VM:: How to run GuixSD in a virtual machine.
179 * Defining Services:: Adding new service definitions.
183 * Base Services:: Essential system services.
184 * Networking Services:: Network setup, SSH daemon, etc.
185 * X Window:: Graphical display.
186 * Desktop Services:: D-Bus and desktop services.
187 * Database Services:: SQL databases.
188 * Mail Services:: IMAP, POP3, SMTP, and all that.
189 * Web Services:: Web servers.
190 * Various Services:: Other services.
194 * Service Composition:: The model for composing services.
195 * Service Types and Services:: Types and services.
196 * Service Reference:: API reference.
197 * Shepherd Services:: A particular type of service.
201 * Software Freedom:: What may go into the distribution.
202 * Package Naming:: What's in a name?
203 * Version Numbers:: When the name is not enough.
204 * Synopses and Descriptions:: Helping users find the right package.
205 * Python Modules:: Taming the snake.
206 * Perl Modules:: Little pearls.
207 * Fonts:: Fond of fonts.
211 * Building from Git:: The latest and greatest.
212 * Running Guix Before It Is Installed:: Hacker tricks.
213 * The Perfect Setup:: The right tools.
214 * Coding Style:: Hygiene of the contributor.
215 * Submitting Patches:: Share your work.
219 * Programming Paradigm:: How to compose your elements.
220 * Modules:: Where to store your code?
221 * Data Types and Pattern Matching:: Implementing data structures.
222 * Formatting Code:: Writing conventions.
227 @c *********************************************************************
229 @chapter Introduction
231 GNU Guix@footnote{``Guix'' is pronounced like ``geeks'', or ``ɡiːks''
232 using the international phonetic alphabet (IPA).} is a functional
233 package management tool for the GNU system. Package management consists
234 of all activities that relate to building packages from sources,
235 honoring their build-time and run-time dependencies,
236 installing packages in user environments, upgrading installed packages
237 to new versions or rolling back to a previous set, removing unused
238 software packages, etc.
240 @cindex functional package management
241 The term @dfn{functional} refers to a specific package management
242 discipline pioneered by Nix (@pxref{Acknowledgments}).
243 In Guix, the package build and installation process is seen
244 as a function, in the mathematical sense. That function takes inputs,
245 such as build scripts, a compiler, and libraries, and
246 returns an installed package. As a pure function, its result depends
247 solely on its inputs---for instance, it cannot refer to software or
248 scripts that were not explicitly passed as inputs. A build function
249 always produces the same result when passed a given set of inputs. It
250 cannot alter the system's environment in
251 any way; for instance, it cannot create, modify, or delete files outside
252 of its build and installation directories. This is achieved by running
253 build processes in isolated environments (or @dfn{containers}), where only their
254 explicit inputs are visible.
257 The result of package build functions is @dfn{cached} in the file
258 system, in a special directory called @dfn{the store} (@pxref{The
259 Store}). Each package is installed in a directory of its own, in the
260 store---by default under @file{/gnu/store}. The directory name contains
261 a hash of all the inputs used to build that package; thus, changing an
262 input yields a different directory name.
264 This approach is the foundation of Guix's salient features: support for
265 transactional package upgrade and rollback, per-user installation, and
266 garbage collection of packages (@pxref{Features}).
268 Guix has a command-line interface, which allows users to build, install,
269 upgrade, and remove packages, as well as a Scheme programming interface.
271 @cindex Guix System Distribution
273 Last but not least, Guix is used to build a distribution of the GNU
274 system, with many GNU and non-GNU free software packages. The Guix
275 System Distribution, or GNU@tie{}GuixSD, takes advantage of the core
276 properties of Guix at the system level. With GuixSD, users
277 @emph{declare} all aspects of the operating system configuration, and
278 Guix takes care of instantiating that configuration in a reproducible,
279 stateless fashion. @xref{GNU Distribution}.
281 @c *********************************************************************
283 @chapter Installation
285 GNU Guix is available for download from its website at
286 @url{http://www.gnu.org/software/guix/}. This section describes the
287 software requirements of Guix, as well as how to install it and get
290 Note that this section is concerned with the installation of the package
291 manager, which can be done on top of a running GNU/Linux system. If,
292 instead, you want to install the complete GNU operating system,
293 @pxref{System Installation}.
296 * Binary Installation:: Getting Guix running in no time!
297 * Requirements:: Software needed to build and run Guix.
298 * Running the Test Suite:: Testing Guix.
299 * Setting Up the Daemon:: Preparing the build daemon's environment.
300 * Invoking guix-daemon:: Running the build daemon.
301 * Application Setup:: Application-specific setup.
304 @node Binary Installation
305 @section Binary Installation
307 This section describes how to install Guix on an arbitrary system from a
308 self-contained tarball providing binaries for Guix and for all its
309 dependencies. This is often quicker than installing from source, which
310 is described in the next sections. The only requirement is to have
313 Installing goes along these lines:
317 Download the binary tarball from
318 @indicateurl{ftp://alpha.gnu.org/gnu/guix/guix-binary-@value{VERSION}.@var{system}.tar.xz},
319 where @var{system} is @code{x86_64-linux} for an @code{x86_64} machine
320 already running the kernel Linux, and so on.
322 Make sure to download the associated @file{.sig} file and to verify the
323 authenticity of the tarball against it, along these lines:
326 $ wget ftp://alpha.gnu.org/gnu/guix/guix-binary-@value{VERSION}.@var{system}.tar.xz.sig
327 $ gpg --verify guix-binary-@value{VERSION}.@var{system}.tar.xz.sig
330 If that command fails because you don't have the required public key,
331 then run this command to import it:
334 $ gpg --keyserver keys.gnupg.net --recv-keys 3D9AEBB5
338 and rerun the @code{gpg --verify} command.
345 # tar --warning=no-timestamp -xf \
346 guix-binary-@value{VERSION}.@var{system}.tar.xz
347 # mv var/guix /var/ && mv gnu /
350 This creates @file{/gnu/store} (@pxref{The Store}) and @file{/var/guix}.
351 The latter contains a ready-to-use profile for @code{root} (see next
354 Do @emph{not} unpack the tarball on a working Guix system since that
355 would overwrite its own essential files.
357 The @code{--warning=no-timestamp} option makes sure GNU@tie{}tar does
358 not emit warnings about ``implausibly old time stamps'' (such
359 warnings were triggered by GNU@tie{}tar 1.26 and older; recent
361 They stem from the fact that all the
362 files in the archive have their modification time set to zero (which
363 means January 1st, 1970.) This is done on purpose to make sure the
364 archive content is independent of its creation time, thus making it
368 Make @code{root}'s profile available under @file{~/.guix-profile}:
371 # ln -sf /var/guix/profiles/per-user/root/guix-profile \
376 Create the group and user accounts for build users as explained below
377 (@pxref{Build Environment Setup}).
383 # ~root/.guix-profile/bin/guix-daemon --build-users-group=guixbuild
386 On hosts using the systemd init system, drop
387 @file{~root/.guix-profile/lib/systemd/system/guix-daemon.service} in
388 @file{/etc/systemd/system}.
390 Likewise, on hosts using the Upstart init system, drop
391 @file{~root/.guix-profile/lib/upstart/system/guix-daemon.conf} in
395 Make the @command{guix} command available to other users on the machine,
399 # mkdir -p /usr/local/bin
401 # ln -s /var/guix/profiles/per-user/root/guix-profile/bin/guix
404 It is also a good idea to make the Info version of this manual available
408 # mkdir -p /usr/local/share/info
409 # cd /usr/local/share/info
410 # for i in /var/guix/profiles/per-user/root/guix-profile/share/info/* ;
414 That way, assuming @file{/usr/local/share/info} is in the search path,
415 running @command{info guix} will open this manual (@pxref{Other Info
416 Directories,,, texinfo, GNU Texinfo}, for more details on changing the
420 To use substitutes from @code{hydra.gnu.org} (@pxref{Substitutes}),
424 # guix archive --authorize < ~root/.guix-profile/share/guix/hydra.gnu.org.pub
428 And that's it! For additional tips and tricks, @pxref{Application
431 The @code{guix} package must remain available in @code{root}'s
432 profile, or it would become subject to garbage collection---in which
433 case you would find yourself badly handicapped by the lack of the
434 @command{guix} command.
436 The tarball in question can be (re)produced and verified simply by
437 running the following command in the Guix source tree:
440 make guix-binary.@var{system}.tar.xz
445 @section Requirements
447 This section lists requirements when building Guix from source. The
448 build procedure for Guix is the same as for other GNU software, and is
449 not covered here. Please see the files @file{README} and @file{INSTALL}
450 in the Guix source tree for additional details.
452 GNU Guix depends on the following packages:
455 @item @url{http://gnu.org/software/guile/, GNU Guile}, version 2.0.7 or later;
456 @item @url{http://gnupg.org/, GNU libgcrypt};
457 @item @url{http://www.gnu.org/software/make/, GNU Make}.
460 The following dependencies are optional:
465 @url{http://savannah.nongnu.org/projects/guile-json/, Guile-JSON} will
466 allow you to use the @command{guix import pypi} command (@pxref{Invoking
467 guix import}). It is of
468 interest primarily for developers and not for casual users.
470 Installing @uref{http://gnutls.org/, GnuTLS-Guile} will
471 allow you to access @code{https} URLs with the @command{guix download}
472 command (@pxref{Invoking guix download}), the @command{guix import pypi}
473 command, and the @command{guix import cpan} command. This is primarily
474 of interest to developers. @xref{Guile Preparations, how to install the
475 GnuTLS bindings for Guile,, gnutls-guile, GnuTLS-Guile}.
478 Unless @code{--disable-daemon} was passed to @command{configure}, the
479 following packages are also needed:
482 @item @url{http://sqlite.org, SQLite 3};
483 @item @url{http://www.bzip.org, libbz2};
484 @item @url{http://gcc.gnu.org, GCC's g++}, with support for the
488 When a working installation of @url{http://nixos.org/nix/, the Nix package
489 manager} is available, you
490 can instead configure Guix with @code{--disable-daemon}. In that case,
491 Nix replaces the three dependencies above.
493 Guix is compatible with Nix, so it is possible to share the same store
494 between both. To do so, you must pass @command{configure} not only the
495 same @code{--with-store-dir} value, but also the same
496 @code{--localstatedir} value. The latter is essential because it
497 specifies where the database that stores metadata about the store is
498 located, among other things. The default values for Nix are
499 @code{--with-store-dir=/nix/store} and @code{--localstatedir=/nix/var}.
500 Note that @code{--disable-daemon} is not required if
501 your goal is to share the store with Nix.
503 @node Running the Test Suite
504 @section Running the Test Suite
506 After a successful @command{configure} and @code{make} run, it is a good
507 idea to run the test suite. It can help catch issues with the setup or
508 environment, or bugs in Guix itself---and really, reporting test
509 failures is a good way to help improve the software. To run the test
516 Test cases can run in parallel: you can use the @code{-j} option of
517 GNU@tie{}make to speed things up. The first run may take a few minutes
518 on a recent machine; subsequent runs will be faster because the store
519 that is created for test purposes will already have various things in
522 It is also possible to run a subset of the tests by defining the
523 @code{TESTS} makefile variable as in this example:
526 make check TESTS="tests/store.scm tests/cpio.scm"
529 Upon failure, please email @email{bug-guix@@gnu.org} and attach the
530 @file{test-suite.log} file. When @file{tests/@var{something}.scm}
531 fails, please also attach the @file{@var{something}.log} file available
532 in the top-level build directory. Please specify the Guix version being
533 used as well as version numbers of the dependencies
534 (@pxref{Requirements}) in your message.
536 @node Setting Up the Daemon
537 @section Setting Up the Daemon
540 Operations such as building a package or running the garbage collector
541 are all performed by a specialized process, the @dfn{build daemon}, on
542 behalf of clients. Only the daemon may access the store and its
543 associated database. Thus, any operation that manipulates the store
544 goes through the daemon. For instance, command-line tools such as
545 @command{guix package} and @command{guix build} communicate with the
546 daemon (@i{via} remote procedure calls) to instruct it what to do.
548 The following sections explain how to prepare the build daemon's
549 environment. Also @ref{Substitutes}, for information on how to allow
550 the daemon to download pre-built binaries.
553 * Build Environment Setup:: Preparing the isolated build environment.
554 * Daemon Offload Setup:: Offloading builds to remote machines.
557 @node Build Environment Setup
558 @subsection Build Environment Setup
560 In a standard multi-user setup, Guix and its daemon---the
561 @command{guix-daemon} program---are installed by the system
562 administrator; @file{/gnu/store} is owned by @code{root} and
563 @command{guix-daemon} runs as @code{root}. Unprivileged users may use
564 Guix tools to build packages or otherwise access the store, and the
565 daemon will do it on their behalf, ensuring that the store is kept in a
566 consistent state, and allowing built packages to be shared among users.
569 When @command{guix-daemon} runs as @code{root}, you may not want package
570 build processes themselves to run as @code{root} too, for obvious
571 security reasons. To avoid that, a special pool of @dfn{build users}
572 should be created for use by build processes started by the daemon.
573 These build users need not have a shell and a home directory: they will
574 just be used when the daemon drops @code{root} privileges in build
575 processes. Having several such users allows the daemon to launch
576 distinct build processes under separate UIDs, which guarantees that they
577 do not interfere with each other---an essential feature since builds are
578 regarded as pure functions (@pxref{Introduction}).
580 On a GNU/Linux system, a build user pool may be created like this (using
581 Bash syntax and the @code{shadow} commands):
583 @c See http://lists.gnu.org/archive/html/bug-guix/2013-01/msg00239.html
584 @c for why `-G' is needed.
586 # groupadd --system guixbuild
587 # for i in `seq -w 1 10`;
589 useradd -g guixbuild -G guixbuild \
590 -d /var/empty -s `which nologin` \
591 -c "Guix build user $i" --system \
597 The number of build users determines how many build jobs may run in
598 parallel, as specified by the @option{--max-jobs} option
599 (@pxref{Invoking guix-daemon, @option{--max-jobs}}). The
600 @code{guix-daemon} program may then be run as @code{root} with the
601 following command@footnote{If your machine uses the systemd init system,
602 dropping the @file{@var{prefix}/lib/systemd/system/guix-daemon.service}
603 file in @file{/etc/systemd/system} will ensure that
604 @command{guix-daemon} is automatically started. Similarly, if your
605 machine uses the Upstart init system, drop the
606 @file{@var{prefix}/lib/upstart/system/guix-daemon.conf}
607 file in @file{/etc/init}.}:
610 # guix-daemon --build-users-group=guixbuild
615 This way, the daemon starts build processes in a chroot, under one of
616 the @code{guixbuilder} users. On GNU/Linux, by default, the chroot
617 environment contains nothing but:
619 @c Keep this list in sync with libstore/build.cc! -----------------------
622 a minimal @code{/dev} directory, created mostly independently from the
623 host @code{/dev}@footnote{``Mostly'', because while the set of files
624 that appear in the chroot's @code{/dev} is fixed, most of these files
625 can only be created if the host has them.};
628 the @code{/proc} directory; it only shows the container's processes
629 since a separate PID name space is used;
632 @file{/etc/passwd} with an entry for the current user and an entry for
636 @file{/etc/group} with an entry for the user's group;
639 @file{/etc/hosts} with an entry that maps @code{localhost} to
643 a writable @file{/tmp} directory.
646 You can influence the directory where the daemon stores build trees
647 @i{via} the @code{TMPDIR} environment variable. However, the build tree
648 within the chroot is always @file{/tmp/guix-build-@var{name}.drv-0},
649 where @var{name} is the derivation name---e.g., @code{coreutils-8.24}.
650 This way, the value of @code{TMPDIR} does not leak inside build
651 environments, which avoids discrepancies in cases where build processes
652 capture the name of their build tree.
655 The daemon also honors the @code{http_proxy} environment variable for
656 HTTP downloads it performs, be it for fixed-output derivations
657 (@pxref{Derivations}) or for substitutes (@pxref{Substitutes}).
659 If you are installing Guix as an unprivileged user, it is still possible
660 to run @command{guix-daemon} provided you pass @code{--disable-chroot}.
661 However, build processes will not be isolated from one another, and not
662 from the rest of the system. Thus, build processes may interfere with
663 each other, and may access programs, libraries, and other files
664 available on the system---making it much harder to view them as
665 @emph{pure} functions.
668 @node Daemon Offload Setup
669 @subsection Using the Offload Facility
673 When desired, the build daemon can @dfn{offload}
674 derivation builds to other machines
675 running Guix, using the @code{offload} @dfn{build hook}. When that
676 feature is enabled, a list of user-specified build machines is read from
677 @file{/etc/guix/machines.scm}; anytime a build is requested, for
678 instance via @code{guix build}, the daemon attempts to offload it to one
679 of the machines that satisfies the derivation's constraints, in
680 particular its system type---e.g., @file{x86_64-linux}. Missing
681 prerequisites for the build are copied over SSH to the target machine,
682 which then proceeds with the build; upon success the output(s) of the
683 build are copied back to the initial machine.
685 The @file{/etc/guix/machines.scm} file typically looks like this:
689 (name "eightysix.example.org")
690 (system "x86_64-linux")
692 (speed 2.)) ; incredibly fast!
695 (name "meeps.example.org")
696 (system "mips64el-linux")
699 (string-append (getenv "HOME")
700 "/.lsh/identity-for-guix"))))
704 In the example above we specify a list of two build machines, one for
705 the @code{x86_64} architecture and one for the @code{mips64el}
708 In fact, this file is---not surprisingly!---a Scheme file that is
709 evaluated when the @code{offload} hook is started. Its return value
710 must be a list of @code{build-machine} objects. While this example
711 shows a fixed list of build machines, one could imagine, say, using
712 DNS-SD to return a list of potential build machines discovered in the
713 local network (@pxref{Introduction, Guile-Avahi,, guile-avahi, Using
714 Avahi in Guile Scheme Programs}). The @code{build-machine} data type is
717 @deftp {Data Type} build-machine
718 This data type represents build machines the daemon may offload builds
719 to. The important fields are:
724 The remote machine's host name.
727 The remote machine's system type---e.g., @code{"x86_64-linux"}.
730 The user account to use when connecting to the remote machine over SSH.
731 Note that the SSH key pair must @emph{not} be passphrase-protected, to
732 allow non-interactive logins.
736 A number of optional fields may be specified:
741 Port number of the machine's SSH server (default: 22).
744 The SSH private key file to use when connecting to the machine.
746 Currently offloading uses GNU@tie{}lsh as its SSH client
747 (@pxref{Invoking lsh,,, GNU lsh Manual}). Thus, the key file here must
748 be an lsh key file. This may change in the future, though.
750 @item parallel-builds
751 The number of builds that may run in parallel on the machine (1 by
755 A ``relative speed factor''. The offload scheduler will tend to prefer
756 machines with a higher speed factor.
759 A list of strings denoting specific features supported by the machine.
760 An example is @code{"kvm"} for machines that have the KVM Linux modules
761 and corresponding hardware support. Derivations can request features by
762 name, and they will be scheduled on matching build machines.
767 The @code{guix} command must be in the search path on the build
768 machines, since offloading works by invoking the @code{guix archive} and
769 @code{guix build} commands. In addition, the Guix modules must be in
770 @code{$GUILE_LOAD_PATH} on the build machine---you can check whether
771 this is the case by running:
774 lsh build-machine guile -c "'(use-modules (guix config))'"
777 There's one last thing to do once @file{machines.scm} is in place. As
778 explained above, when offloading, files are transferred back and forth
779 between the machine stores. For this to work, you first need to
780 generate a key pair on each machine to allow the daemon to export signed
781 archives of files from the store (@pxref{Invoking guix archive}):
784 # guix archive --generate-key
788 Each build machine must authorize the key of the master machine so that
789 it accepts store items it receives from the master:
792 # guix archive --authorize < master-public-key.txt
796 Likewise, the master machine must authorize the key of each build machine.
798 All the fuss with keys is here to express pairwise mutual trust
799 relations between the master and the build machines. Concretely, when
800 the master receives files from a build machine (and @i{vice versa}), its
801 build daemon can make sure they are genuine, have not been tampered
802 with, and that they are signed by an authorized key.
805 @node Invoking guix-daemon
806 @section Invoking @command{guix-daemon}
808 The @command{guix-daemon} program implements all the functionality to
809 access the store. This includes launching build processes, running the
810 garbage collector, querying the availability of a build result, etc. It
811 is normally run as @code{root} like this:
814 # guix-daemon --build-users-group=guixbuild
818 For details on how to set it up, @pxref{Setting Up the Daemon}.
821 @cindex container, build environment
822 @cindex build environment
823 @cindex reproducible builds
824 By default, @command{guix-daemon} launches build processes under
825 different UIDs, taken from the build group specified with
826 @code{--build-users-group}. In addition, each build process is run in a
827 chroot environment that only contains the subset of the store that the
828 build process depends on, as specified by its derivation
829 (@pxref{Programming Interface, derivation}), plus a set of specific
830 system directories. By default, the latter contains @file{/dev} and
831 @file{/dev/pts}. Furthermore, on GNU/Linux, the build environment is a
832 @dfn{container}: in addition to having its own file system tree, it has
833 a separate mount name space, its own PID name space, network name space,
834 etc. This helps achieve reproducible builds (@pxref{Features}).
836 When the daemon performs a build on behalf of the user, it creates a
837 build directory under @file{/tmp} or under the directory specified by
838 its @code{TMPDIR} environment variable; this directory is shared with
839 the container for the duration of the build. Be aware that using a
840 directory other than @file{/tmp} can affect build results---for example,
841 with a longer directory name, a build process that uses Unix-domain
842 sockets might hit the name length limitation for @code{sun_path}, which
843 it would otherwise not hit.
845 The build directory is automatically deleted upon completion, unless the
846 build failed and the client specified @option{--keep-failed}
847 (@pxref{Invoking guix build, @option{--keep-failed}}).
849 The following command-line options are supported:
852 @item --build-users-group=@var{group}
853 Take users from @var{group} to run build processes (@pxref{Setting Up
854 the Daemon, build users}).
856 @item --no-substitutes
858 Do not use substitutes for build products. That is, always build things
859 locally instead of allowing downloads of pre-built binaries
860 (@pxref{Substitutes}).
862 By default substitutes are used, unless the client---such as the
863 @command{guix package} command---is explicitly invoked with
864 @code{--no-substitutes}.
866 When the daemon runs with @code{--no-substitutes}, clients can still
867 explicitly enable substitution @i{via} the @code{set-build-options}
868 remote procedure call (@pxref{The Store}).
870 @item --substitute-urls=@var{urls}
871 @anchor{daemon-substitute-urls}
872 Consider @var{urls} the default whitespace-separated list of substitute
873 source URLs. When this option is omitted, @indicateurl{http://hydra.gnu.org}
876 This means that substitutes may be downloaded from @var{urls}, as long
877 as they are signed by a trusted signature (@pxref{Substitutes}).
880 @item --no-build-hook
881 Do not use the @dfn{build hook}.
883 The build hook is a helper program that the daemon can start and to
884 which it submits build requests. This mechanism is used to offload
885 builds to other machines (@pxref{Daemon Offload Setup}).
887 @item --cache-failures
888 Cache build failures. By default, only successful builds are cached.
890 When this option is used, @command{guix gc --list-failures} can be used
891 to query the set of store items marked as failed; @command{guix gc
892 --clear-failures} removes store items from the set of cached failures.
893 @xref{Invoking guix gc}.
895 @item --cores=@var{n}
897 Use @var{n} CPU cores to build each derivation; @code{0} means as many
900 The default value is @code{0}, but it may be overridden by clients, such
901 as the @code{--cores} option of @command{guix build} (@pxref{Invoking
904 The effect is to define the @code{NIX_BUILD_CORES} environment variable
905 in the build process, which can then use it to exploit internal
906 parallelism---for instance, by running @code{make -j$NIX_BUILD_CORES}.
908 @item --max-jobs=@var{n}
910 Allow at most @var{n} build jobs in parallel. The default value is
911 @code{1}. Setting it to @code{0} means that no builds will be performed
912 locally; instead, the daemon will offload builds (@pxref{Daemon Offload
913 Setup}), or simply fail.
915 @item --rounds=@var{N}
916 Build each derivation @var{n} times in a row, and raise an error if
917 consecutive build results are not bit-for-bit identical. Note that this
918 setting can be overridden by clients such as @command{guix build}
919 (@pxref{Invoking guix build}).
922 Produce debugging output.
924 This is useful to debug daemon start-up issues, but then it may be
925 overridden by clients, for example the @code{--verbosity} option of
926 @command{guix build} (@pxref{Invoking guix build}).
928 @item --chroot-directory=@var{dir}
929 Add @var{dir} to the build chroot.
931 Doing this may change the result of build processes---for instance if
932 they use optional dependencies found in @var{dir} when it is available,
933 and not otherwise. For that reason, it is not recommended to do so.
934 Instead, make sure that each derivation declares all the inputs that it
937 @item --disable-chroot
938 Disable chroot builds.
940 Using this option is not recommended since, again, it would allow build
941 processes to gain access to undeclared dependencies. It is necessary,
942 though, when @command{guix-daemon} is running under an unprivileged user
945 @item --disable-log-compression
946 Disable compression of the build logs.
948 Unless @code{--lose-logs} is used, all the build logs are kept in the
949 @var{localstatedir}. To save space, the daemon automatically compresses
950 them with bzip2 by default. This option disables that.
952 @item --disable-deduplication
953 @cindex deduplication
954 Disable automatic file ``deduplication'' in the store.
956 By default, files added to the store are automatically ``deduplicated'':
957 if a newly added file is identical to another one found in the store,
958 the daemon makes the new file a hard link to the other file. This can
959 noticeably reduce disk usage, at the expense of slightly increased
960 input/output load at the end of a build process. This option disables
963 @item --gc-keep-outputs[=yes|no]
964 Tell whether the garbage collector (GC) must keep outputs of live
967 When set to ``yes'', the GC will keep the outputs of any live derivation
968 available in the store---the @code{.drv} files. The default is ``no'',
969 meaning that derivation outputs are kept only if they are GC roots.
971 @item --gc-keep-derivations[=yes|no]
972 Tell whether the garbage collector (GC) must keep derivations
973 corresponding to live outputs.
975 When set to ``yes'', as is the case by default, the GC keeps
976 derivations---i.e., @code{.drv} files---as long as at least one of their
977 outputs is live. This allows users to keep track of the origins of
978 items in their store. Setting it to ``no'' saves a bit of disk space.
980 Note that when both @code{--gc-keep-derivations} and
981 @code{--gc-keep-outputs} are used, the effect is to keep all the build
982 prerequisites (the sources, compiler, libraries, and other build-time
983 tools) of live objects in the store, regardless of whether these
984 prerequisites are live. This is convenient for developers since it
985 saves rebuilds or downloads.
987 @item --impersonate-linux-2.6
988 On Linux-based systems, impersonate Linux 2.6. This means that the
989 kernel's @code{uname} system call will report 2.6 as the release number.
991 This might be helpful to build programs that (usually wrongfully) depend
992 on the kernel version number.
995 Do not keep build logs. By default they are kept under
996 @code{@var{localstatedir}/guix/log}.
998 @item --system=@var{system}
999 Assume @var{system} as the current system type. By default it is the
1000 architecture/kernel pair found at configure time, such as
1001 @code{x86_64-linux}.
1003 @item --listen=@var{socket}
1004 Listen for connections on @var{socket}, the file name of a Unix-domain
1005 socket. The default socket is
1006 @file{@var{localstatedir}/daemon-socket/socket}. This option is only
1007 useful in exceptional circumstances, such as if you need to run several
1008 daemons on the same machine.
1012 @node Application Setup
1013 @section Application Setup
1015 When using Guix on top of GNU/Linux distribution other than GuixSD---a
1016 so-called @dfn{foreign distro}---a few additional steps are needed to
1017 get everything in place. Here are some of them.
1021 @anchor{locales-and-locpath}
1022 @cindex locales, when not on GuixSD
1024 @vindex GUIX_LOCPATH
1025 Packages installed @i{via} Guix will not use the host system's locale
1026 data. Instead, you must first install one of the locale packages
1027 available with Guix and then define the @code{GUIX_LOCPATH} environment
1031 $ guix package -i glibc-locales
1032 $ export GUIX_LOCPATH=$HOME/.guix-profile/lib/locale
1035 Note that the @code{glibc-locales} package contains data for all the
1036 locales supported by the GNU@tie{}libc and weighs in at around
1037 110@tie{}MiB. Alternately, the @code{glibc-utf8-locales} is smaller but
1038 limited to a few UTF-8 locales.
1040 The @code{GUIX_LOCPATH} variable plays a role similar to @code{LOCPATH}
1041 (@pxref{Locale Names, @code{LOCPATH},, libc, The GNU C Library Reference
1042 Manual}). There are two important differences though:
1046 @code{GUIX_LOCPATH} is honored only by Guix's libc, and not by the libc
1047 provided by foreign distros. Thus, using @code{GUIX_LOCPATH} allows you
1048 to make sure the foreign distro's programs will not end up loading
1049 incompatible locale data.
1052 libc suffixes each entry of @code{GUIX_LOCPATH} with @code{/X.Y}, where
1053 @code{X.Y} is the libc version---e.g., @code{2.22}. This means that,
1054 should your Guix profile contain a mixture of programs linked against
1055 different libc version, each libc version will only try to load locale
1056 data in the right format.
1059 This is important because the locale data format used by different libc
1060 versions may be incompatible.
1062 @subsection X11 Fonts
1064 The majority of graphical applications use Fontconfig to locate and
1065 load fonts and perform X11-client-side rendering. Guix's
1066 @code{fontconfig} package looks for fonts in @file{$HOME/.guix-profile}
1067 by default. Thus, to allow graphical applications installed with Guix
1068 to display fonts, you will have to install fonts with Guix as well.
1069 Essential font packages include @code{gs-fonts}, @code{font-dejavu}, and
1070 @code{font-gnu-freefont-ttf}.
1072 To display text written in Chinese languages, Japanese, or Korean in
1073 graphical applications, consider installing
1074 @code{font-adobe-source-han-sans} or @code{font-wqy-zenhei}. The former
1075 has multiple outputs, one per language family (@pxref{Packages with
1076 Multiple Outputs}). For instance, the following command installs fonts
1077 for Chinese languages:
1080 guix package -i font-adobe-source-han-sans:cn
1083 @subsection Emacs Packages
1085 When you install Emacs packages with Guix, the elisp files may be placed
1086 either in @file{$HOME/.guix-profile/share/emacs/site-lisp/} or in
1088 @file{$HOME/.guix-profile/share/emacs/site-lisp/guix.d/}. The latter
1089 directory exists because potentially there may exist thousands of Emacs
1090 packages and storing all their files in a single directory may be not
1091 reliable (because of name conflicts). So we think using a separate
1092 directory for each package is a good idea. It is very similar to how
1093 the Emacs package system organizes the file structure (@pxref{Package
1094 Files,,, emacs, The GNU Emacs Manual}).
1096 By default, Emacs (installed with Guix) ``knows'' where these packages
1097 are placed, so you don't need to perform any configuration. If, for
1098 some reason, you want to avoid auto-loading Emacs packages installed
1099 with Guix, you can do it by running Emacs with @code{--no-site-file}
1100 option (@pxref{Init File,,, emacs, The GNU Emacs Manual}).
1104 @c *********************************************************************
1105 @node Package Management
1106 @chapter Package Management
1108 The purpose of GNU Guix is to allow users to easily install, upgrade, and
1109 remove software packages, without having to know about their build
1110 procedure or dependencies. Guix also goes beyond this obvious set of
1113 This chapter describes the main features of Guix, as well as the package
1114 management tools it provides. Two user interfaces are provided for
1115 routine package management tasks: A command-line interface described below
1116 (@pxref{Invoking guix package, @code{guix package}}), as well as a visual user
1117 interface in Emacs described in a subsequent chapter (@pxref{Emacs Interface}).
1120 * Features:: How Guix will make your life brighter.
1121 * Invoking guix package:: Package installation, removal, etc.
1122 * Substitutes:: Downloading pre-built binaries.
1123 * Packages with Multiple Outputs:: Single source package, multiple outputs.
1124 * Invoking guix gc:: Running the garbage collector.
1125 * Invoking guix pull:: Fetching the latest Guix and distribution.
1126 * Invoking guix archive:: Exporting and importing store files.
1132 When using Guix, each package ends up in the @dfn{package store}, in its
1133 own directory---something that resembles
1134 @file{/gnu/store/xxx-package-1.2}, where @code{xxx} is a base32 string
1135 (note that Guix comes with an Emacs extension to shorten those file
1136 names, @pxref{Emacs Prettify}.)
1138 Instead of referring to these directories, users have their own
1139 @dfn{profile}, which points to the packages that they actually want to
1140 use. These profiles are stored within each user's home directory, at
1141 @code{$HOME/.guix-profile}.
1143 For example, @code{alice} installs GCC 4.7.2. As a result,
1144 @file{/home/alice/.guix-profile/bin/gcc} points to
1145 @file{/gnu/store/@dots{}-gcc-4.7.2/bin/gcc}. Now, on the same machine,
1146 @code{bob} had already installed GCC 4.8.0. The profile of @code{bob}
1147 simply continues to point to
1148 @file{/gnu/store/@dots{}-gcc-4.8.0/bin/gcc}---i.e., both versions of GCC
1149 coexist on the same system without any interference.
1151 The @command{guix package} command is the central tool to manage
1152 packages (@pxref{Invoking guix package}). It operates on those per-user
1153 profiles, and can be used @emph{with normal user privileges}.
1155 The command provides the obvious install, remove, and upgrade
1156 operations. Each invocation is actually a @emph{transaction}: either
1157 the specified operation succeeds, or nothing happens. Thus, if the
1158 @command{guix package} process is terminated during the transaction,
1159 or if a power outage occurs during the transaction, then the user's
1160 profile remains in its previous state, and remains usable.
1162 In addition, any package transaction may be @emph{rolled back}. So, if,
1163 for example, an upgrade installs a new version of a package that turns
1164 out to have a serious bug, users may roll back to the previous instance
1165 of their profile, which was known to work well. Similarly, the global
1166 system configuration is subject to transactional upgrades and roll-back
1167 (@pxref{Using the Configuration System}).
1169 All those packages in the package store may be @emph{garbage-collected}.
1170 Guix can determine which packages are still referenced by the user
1171 profiles, and remove those that are provably no longer referenced
1172 (@pxref{Invoking guix gc}). Users may also explicitly remove old
1173 generations of their profile so that the packages they refer to can be
1176 @cindex reproducibility
1177 @cindex reproducible builds
1178 Finally, Guix takes a @dfn{purely functional} approach to package
1179 management, as described in the introduction (@pxref{Introduction}).
1180 Each @file{/gnu/store} package directory name contains a hash of all the
1181 inputs that were used to build that package---compiler, libraries, build
1182 scripts, etc. This direct correspondence allows users to make sure a
1183 given package installation matches the current state of their
1184 distribution. It also helps maximize @dfn{build reproducibility}:
1185 thanks to the isolated build environments that are used, a given build
1186 is likely to yield bit-identical files when performed on different
1187 machines (@pxref{Invoking guix-daemon, container}).
1190 This foundation allows Guix to support @dfn{transparent binary/source
1191 deployment}. When a pre-built binary for a @file{/gnu/store} item is
1192 available from an external source---a @dfn{substitute}, Guix just
1193 downloads it and unpacks it;
1194 otherwise, it builds the package from source, locally
1195 (@pxref{Substitutes}).
1197 Control over the build environment is a feature that is also useful for
1198 developers. The @command{guix environment} command allows developers of
1199 a package to quickly set up the right development environment for their
1200 package, without having to manually install the package's dependencies
1201 in their profile (@pxref{Invoking guix environment}).
1203 @node Invoking guix package
1204 @section Invoking @command{guix package}
1206 The @command{guix package} command is the tool that allows users to
1207 install, upgrade, and remove packages, as well as rolling back to
1208 previous configurations. It operates only on the user's own profile,
1209 and works with normal user privileges (@pxref{Features}). Its syntax
1213 guix package @var{options}
1216 Primarily, @var{options} specifies the operations to be performed during
1217 the transaction. Upon completion, a new profile is created, but
1218 previous @dfn{generations} of the profile remain available, should the user
1221 For example, to remove @code{lua} and install @code{guile} and
1222 @code{guile-cairo} in a single transaction:
1225 guix package -r lua -i guile guile-cairo
1228 @command{guix package} also supports a @dfn{declarative approach}
1229 whereby the user specifies the exact set of packages to be available and
1230 passes it @i{via} the @option{--manifest} option
1231 (@pxref{profile-manifest, @option{--manifest}}).
1233 For each user, a symlink to the user's default profile is automatically
1234 created in @file{$HOME/.guix-profile}. This symlink always points to the
1235 current generation of the user's default profile. Thus, users can add
1236 @file{$HOME/.guix-profile/bin} to their @code{PATH} environment
1237 variable, and so on.
1238 @cindex search paths
1239 If you are not using the Guix System Distribution, consider adding the
1240 following lines to your @file{~/.bash_profile} (@pxref{Bash Startup
1241 Files,,, bash, The GNU Bash Reference Manual}) so that newly-spawned
1242 shells get all the right environment variable definitions:
1245 GUIX_PROFILE="$HOME/.guix-profile" \
1246 source "$HOME/.guix-profile/etc/profile"
1249 In a multi-user setup, user profiles are stored in a place registered as
1250 a @dfn{garbage-collector root}, which @file{$HOME/.guix-profile} points
1251 to (@pxref{Invoking guix gc}). That directory is normally
1252 @code{@var{localstatedir}/profiles/per-user/@var{user}}, where
1253 @var{localstatedir} is the value passed to @code{configure} as
1254 @code{--localstatedir}, and @var{user} is the user name. The
1255 @file{per-user} directory is created when @command{guix-daemon} is
1256 started, and the @var{user} sub-directory is created by @command{guix
1259 The @var{options} can be among the following:
1263 @item --install=@var{package} @dots{}
1264 @itemx -i @var{package} @dots{}
1265 Install the specified @var{package}s.
1267 Each @var{package} may specify either a simple package name, such as
1268 @code{guile}, or a package name followed by a hyphen and version number,
1269 such as @code{guile-1.8.8} or simply @code{guile-1.8} (in the latter
1270 case, the newest version prefixed by @code{1.8} is selected.)
1272 If no version number is specified, the
1273 newest available version will be selected. In addition, @var{package}
1274 may contain a colon, followed by the name of one of the outputs of the
1275 package, as in @code{gcc:doc} or @code{binutils-2.22:lib}
1276 (@pxref{Packages with Multiple Outputs}). Packages with a corresponding
1277 name (and optionally version) are searched for among the GNU
1278 distribution modules (@pxref{Package Modules}).
1280 @cindex propagated inputs
1281 Sometimes packages have @dfn{propagated inputs}: these are dependencies
1282 that automatically get installed along with the required package
1283 (@pxref{package-propagated-inputs, @code{propagated-inputs} in
1284 @code{package} objects}, for information about propagated inputs in
1285 package definitions).
1287 @anchor{package-cmd-propagated-inputs}
1288 An example is the GNU MPC library: its C header files refer to those of
1289 the GNU MPFR library, which in turn refer to those of the GMP library.
1290 Thus, when installing MPC, the MPFR and GMP libraries also get installed
1291 in the profile; removing MPC also removes MPFR and GMP---unless they had
1292 also been explicitly installed independently.
1294 Besides, packages sometimes rely on the definition of environment
1295 variables for their search paths (see explanation of
1296 @code{--search-paths} below). Any missing or possibly incorrect
1297 environment variable definitions are reported here.
1299 @c XXX: keep me up-to-date
1300 Finally, when installing a GNU package, the tool reports the
1301 availability of a newer upstream version. In the future, it may provide
1302 the option of installing directly from the upstream version, even if
1303 that version is not yet in the distribution.
1305 @item --install-from-expression=@var{exp}
1307 Install the package @var{exp} evaluates to.
1309 @var{exp} must be a Scheme expression that evaluates to a
1310 @code{<package>} object. This option is notably useful to disambiguate
1311 between same-named variants of a package, with expressions such as
1312 @code{(@@ (gnu packages base) guile-final)}.
1314 Note that this option installs the first output of the specified
1315 package, which may be insufficient when needing a specific output of a
1316 multiple-output package.
1318 @item --install-from-file=@var{file}
1319 @itemx -f @var{file}
1320 Install the package that the code within @var{file} evaluates to.
1322 As an example, @var{file} might contain a definition like this
1323 (@pxref{Defining Packages}):
1326 @verbatiminclude package-hello.scm
1329 Developers may find it useful to include such a @file{package.scm} file
1330 in the root of their project's source tree that can be used to test
1331 development snapshots and create reproducible development environments
1332 (@pxref{Invoking guix environment}).
1334 @item --remove=@var{package} @dots{}
1335 @itemx -r @var{package} @dots{}
1336 Remove the specified @var{package}s.
1338 As for @code{--install}, each @var{package} may specify a version number
1339 and/or output name in addition to the package name. For instance,
1340 @code{-r glibc:debug} would remove the @code{debug} output of
1343 @item --upgrade[=@var{regexp} @dots{}]
1344 @itemx -u [@var{regexp} @dots{}]
1345 Upgrade all the installed packages. If one or more @var{regexp}s are
1346 specified, upgrade only installed packages whose name matches a
1347 @var{regexp}. Also see the @code{--do-not-upgrade} option below.
1349 Note that this upgrades package to the latest version of packages found
1350 in the distribution currently installed. To update your distribution,
1351 you should regularly run @command{guix pull} (@pxref{Invoking guix
1354 @item --do-not-upgrade[=@var{regexp} @dots{}]
1355 When used together with the @code{--upgrade} option, do @emph{not}
1356 upgrade any packages whose name matches a @var{regexp}. For example, to
1357 upgrade all packages in the current profile except those containing the
1358 substring ``emacs'':
1361 $ guix package --upgrade . --do-not-upgrade emacs
1364 @item @anchor{profile-manifest}--manifest=@var{file}
1365 @itemx -m @var{file}
1366 @cindex profile declaration
1367 @cindex profile manifest
1368 Create a new generation of the profile from the manifest object
1369 returned by the Scheme code in @var{file}.
1371 This allows you to @emph{declare} the profile's contents rather than
1372 constructing it through a sequence of @code{--install} and similar
1373 commands. The advantage is that @var{file} can be put under version
1374 control, copied to different machines to reproduce the same profile, and
1377 @c FIXME: Add reference to (guix profile) documentation when available.
1378 @var{file} must return a @dfn{manifest} object, which is roughly a list
1381 @findex packages->manifest
1383 (use-package-modules guile emacs)
1388 ;; Use a specific package output.
1389 (list guile-2.0 "debug")))
1393 Roll back to the previous @dfn{generation} of the profile---i.e., undo
1394 the last transaction.
1396 When combined with options such as @code{--install}, roll back occurs
1397 before any other actions.
1399 When rolling back from the first generation that actually contains
1400 installed packages, the profile is made to point to the @dfn{zeroth
1401 generation}, which contains no files apart from its own meta-data.
1403 Installing, removing, or upgrading packages from a generation that has
1404 been rolled back to overwrites previous future generations. Thus, the
1405 history of a profile's generations is always linear.
1407 @item --switch-generation=@var{pattern}
1408 @itemx -S @var{pattern}
1409 Switch to a particular generation defined by @var{pattern}.
1411 @var{pattern} may be either a generation number or a number prefixed
1412 with ``+'' or ``-''. The latter means: move forward/backward by a
1413 specified number of generations. For example, if you want to return to
1414 the latest generation after @code{--roll-back}, use
1415 @code{--switch-generation=+1}.
1417 The difference between @code{--roll-back} and
1418 @code{--switch-generation=-1} is that @code{--switch-generation} will
1419 not make a zeroth generation, so if a specified generation does not
1420 exist, the current generation will not be changed.
1422 @item --search-paths[=@var{kind}]
1423 @cindex search paths
1424 Report environment variable definitions, in Bash syntax, that may be
1425 needed in order to use the set of installed packages. These environment
1426 variables are used to specify @dfn{search paths} for files used by some
1427 of the installed packages.
1429 For example, GCC needs the @code{CPATH} and @code{LIBRARY_PATH}
1430 environment variables to be defined so it can look for headers and
1431 libraries in the user's profile (@pxref{Environment Variables,,, gcc,
1432 Using the GNU Compiler Collection (GCC)}). If GCC and, say, the C
1433 library are installed in the profile, then @code{--search-paths} will
1434 suggest setting these variables to @code{@var{profile}/include} and
1435 @code{@var{profile}/lib}, respectively.
1437 The typical use case is to define these environment variables in the
1441 $ eval `guix package --search-paths`
1444 @var{kind} may be one of @code{exact}, @code{prefix}, or @code{suffix},
1445 meaning that the returned environment variable definitions will either
1446 be exact settings, or prefixes or suffixes of the current value of these
1447 variables. When omitted, @var{kind} defaults to @code{exact}.
1449 This option can also be used to compute the @emph{combined} search paths
1450 of several profiles. Consider this example:
1453 $ guix package -p foo -i guile
1454 $ guix package -p bar -i guile-json
1455 $ guix package -p foo -p bar --search-paths
1458 The last command above reports about the @code{GUILE_LOAD_PATH}
1459 variable, even though, taken individually, neither @file{foo} nor
1460 @file{bar} would lead to that recommendation.
1463 @item --profile=@var{profile}
1464 @itemx -p @var{profile}
1465 Use @var{profile} instead of the user's default profile.
1468 Produce verbose output. In particular, emit the environment's build log
1469 on the standard error port.
1472 Use the bootstrap Guile to build the profile. This option is only
1473 useful to distribution developers.
1477 In addition to these actions @command{guix package} supports the
1478 following options to query the current state of a profile, or the
1479 availability of packages:
1483 @item --search=@var{regexp}
1484 @itemx -s @var{regexp}
1485 @cindex searching for packages
1486 List the available packages whose name, synopsis, or description matches
1487 @var{regexp}. Print all the meta-data of matching packages in
1488 @code{recutils} format (@pxref{Top, GNU recutils databases,, recutils,
1489 GNU recutils manual}).
1491 This allows specific fields to be extracted using the @command{recsel}
1492 command, for instance:
1495 $ guix package -s malloc | recsel -p name,version
1503 Similarly, to show the name of all the packages available under the
1504 terms of the GNU@tie{}LGPL version 3:
1507 $ guix package -s "" | recsel -p name -e 'license ~ "LGPL 3"'
1514 It is also possible to refine search results using several @code{-s}
1515 flags. For example, the following command returns a list of board
1519 $ guix package -s '\<board\>' -s game | recsel -p name
1524 If we were to omit @code{-s game}, we would also get software packages
1525 that deal with printed circuit boards; removing the angle brackets
1526 around @code{board} would further add packages that have to do with
1529 And now for a more elaborate example. The following command searches
1530 for cryptographic libraries, filters out Haskell, Perl, Python, and Ruby
1531 libraries, and prints the name and synopsis of the matching packages:
1534 $ guix package -s crypto -s library | \
1535 recsel -e '! (name ~ "^(ghc|perl|python|ruby)")' -p name,synopsis
1539 @xref{Selection Expressions,,, recutils, GNU recutils manual}, for more
1540 information on @dfn{selection expressions} for @code{recsel -e}.
1542 @item --show=@var{package}
1543 Show details about @var{package}, taken from the list of available packages, in
1544 @code{recutils} format (@pxref{Top, GNU recutils databases,, recutils, GNU
1548 $ guix package --show=python | recsel -p name,version
1556 You may also specify the full name of a package to only get details about a
1557 specific version of it:
1559 $ guix package --show=python-3.3.5 | recsel -p name,version
1566 @item --list-installed[=@var{regexp}]
1567 @itemx -I [@var{regexp}]
1568 List the currently installed packages in the specified profile, with the
1569 most recently installed packages shown last. When @var{regexp} is
1570 specified, list only installed packages whose name matches @var{regexp}.
1572 For each installed package, print the following items, separated by
1573 tabs: the package name, its version string, the part of the package that
1574 is installed (for instance, @code{out} for the default output,
1575 @code{include} for its headers, etc.), and the path of this package in
1578 @item --list-available[=@var{regexp}]
1579 @itemx -A [@var{regexp}]
1580 List packages currently available in the distribution for this system
1581 (@pxref{GNU Distribution}). When @var{regexp} is specified, list only
1582 installed packages whose name matches @var{regexp}.
1584 For each package, print the following items separated by tabs: its name,
1585 its version string, the parts of the package (@pxref{Packages with
1586 Multiple Outputs}), and the source location of its definition.
1588 @item --list-generations[=@var{pattern}]
1589 @itemx -l [@var{pattern}]
1590 Return a list of generations along with their creation dates; for each
1591 generation, show the installed packages, with the most recently
1592 installed packages shown last. Note that the zeroth generation is never
1595 For each installed package, print the following items, separated by
1596 tabs: the name of a package, its version string, the part of the package
1597 that is installed (@pxref{Packages with Multiple Outputs}), and the
1598 location of this package in the store.
1600 When @var{pattern} is used, the command returns only matching
1601 generations. Valid patterns include:
1604 @item @emph{Integers and comma-separated integers}. Both patterns denote
1605 generation numbers. For instance, @code{--list-generations=1} returns
1608 And @code{--list-generations=1,8,2} outputs three generations in the
1609 specified order. Neither spaces nor trailing commas are allowed.
1611 @item @emph{Ranges}. @code{--list-generations=2..9} prints the
1612 specified generations and everything in between. Note that the start of
1613 a range must be lesser than its end.
1615 It is also possible to omit the endpoint. For example,
1616 @code{--list-generations=2..}, returns all generations starting from the
1619 @item @emph{Durations}. You can also get the last @emph{N}@tie{}days, weeks,
1620 or months by passing an integer along with the first letter of the
1621 duration. For example, @code{--list-generations=20d} lists generations
1622 that are up to 20 days old.
1625 @item --delete-generations[=@var{pattern}]
1626 @itemx -d [@var{pattern}]
1627 When @var{pattern} is omitted, delete all generations except the current
1630 This command accepts the same patterns as @option{--list-generations}.
1631 When @var{pattern} is specified, delete the matching generations. When
1632 @var{pattern} specifies a duration, generations @emph{older} than the
1633 specified duration match. For instance, @code{--delete-generations=1m}
1634 deletes generations that are more than one month old.
1636 If the current generation matches, it is @emph{not} deleted. Also, the
1637 zeroth generation is never deleted.
1639 Note that deleting generations prevents roll-back to them.
1640 Consequently, this command must be used with care.
1644 Finally, since @command{guix package} may actually start build
1645 processes, it supports all the common build options (@pxref{Common Build
1649 @section Substitutes
1652 @cindex pre-built binaries
1653 Guix supports transparent source/binary deployment, which means that it
1654 can either build things locally, or download pre-built items from a
1655 server. We call these pre-built items @dfn{substitutes}---they are
1656 substitutes for local build results. In many cases, downloading a
1657 substitute is much faster than building things locally.
1659 Substitutes can be anything resulting from a derivation build
1660 (@pxref{Derivations}). Of course, in the common case, they are
1661 pre-built package binaries, but source tarballs, for instance, which
1662 also result from derivation builds, can be available as substitutes.
1664 The @code{hydra.gnu.org} server is a front-end to a build farm that
1665 builds packages from the GNU distribution continuously for some
1666 architectures, and makes them available as substitutes (@pxref{Emacs
1667 Hydra}, for information on how to query the continuous integration
1668 server). This is the
1669 default source of substitutes; it can be overridden by passing the
1670 @option{--substitute-urls} option either to @command{guix-daemon}
1671 (@pxref{daemon-substitute-urls,, @code{guix-daemon --substitute-urls}})
1672 or to client tools such as @command{guix package}
1673 (@pxref{client-substitute-urls,, client @option{--substitute-urls}
1677 @cindex digital signatures
1678 To allow Guix to download substitutes from @code{hydra.gnu.org}, you
1679 must add its public key to the access control list (ACL) of archive
1680 imports, using the @command{guix archive} command (@pxref{Invoking guix
1681 archive}). Doing so implies that you trust @code{hydra.gnu.org} to not
1682 be compromised and to serve genuine substitutes.
1684 This public key is installed along with Guix, in
1685 @code{@var{prefix}/share/guix/hydra.gnu.org.pub}, where @var{prefix} is
1686 the installation prefix of Guix. If you installed Guix from source,
1687 make sure you checked the GPG signature of
1688 @file{guix-@value{VERSION}.tar.gz}, which contains this public key file.
1689 Then, you can run something like this:
1692 # guix archive --authorize < hydra.gnu.org.pub
1695 Once this is in place, the output of a command like @code{guix build}
1696 should change from something like:
1699 $ guix build emacs --dry-run
1700 The following derivations would be built:
1701 /gnu/store/yr7bnx8xwcayd6j95r2clmkdl1qh688w-emacs-24.3.drv
1702 /gnu/store/x8qsh1hlhgjx6cwsjyvybnfv2i37z23w-dbus-1.6.4.tar.gz.drv
1703 /gnu/store/1ixwp12fl950d15h2cj11c73733jay0z-alsa-lib-1.0.27.1.tar.bz2.drv
1704 /gnu/store/nlma1pw0p603fpfiqy7kn4zm105r5dmw-util-linux-2.21.drv
1712 $ guix build emacs --dry-run
1713 The following files would be downloaded:
1714 /gnu/store/pk3n22lbq6ydamyymqkkz7i69wiwjiwi-emacs-24.3
1715 /gnu/store/2ygn4ncnhrpr61rssa6z0d9x22si0va3-libjpeg-8d
1716 /gnu/store/71yz6lgx4dazma9dwn2mcjxaah9w77jq-cairo-1.12.16
1717 /gnu/store/7zdhgp0n1518lvfn8mb96sxqfmvqrl7v-libxrender-0.9.7
1722 This indicates that substitutes from @code{hydra.gnu.org} are usable and
1723 will be downloaded, when possible, for future builds.
1725 Guix ignores substitutes that are not signed, or that are not signed by
1726 one of the keys listed in the ACL. It also detects and raises an error
1727 when attempting to use a substitute that has been tampered with.
1730 Substitutes are downloaded over HTTP. The @code{http_proxy} environment
1731 variable can be set in the environment of @command{guix-daemon} and is
1732 honored for downloads of substitutes. Note that the value of
1733 @code{http_proxy} in the environment where @command{guix build},
1734 @command{guix package}, and other client commands are run has
1735 @emph{absolutely no effect}.
1737 The substitute mechanism can be disabled globally by running
1738 @code{guix-daemon} with @code{--no-substitutes} (@pxref{Invoking
1739 guix-daemon}). It can also be disabled temporarily by passing the
1740 @code{--no-substitutes} option to @command{guix package}, @command{guix
1741 build}, and other command-line tools.
1744 Today, each individual's control over their own computing is at the
1745 mercy of institutions, corporations, and groups with enough power and
1746 determination to subvert the computing infrastructure and exploit its
1747 weaknesses. While using @code{hydra.gnu.org} substitutes can be
1748 convenient, we encourage users to also build on their own, or even run
1749 their own build farm, such that @code{hydra.gnu.org} is less of an
1750 interesting target. One way to help is by publishing the software you
1751 build using @command{guix publish} so that others have one more choice
1752 of server to download substitutes from (@pxref{Invoking guix publish}).
1754 Guix has the foundations to maximize build reproducibility
1755 (@pxref{Features}). In most cases, independent builds of a given
1756 package or derivation should yield bit-identical results. Thus, through
1757 a diverse set of independent package builds, we can strengthen the
1758 integrity of our systems. The @command{guix challenge} command aims to
1759 help users assess substitute servers, and to assist developers in
1760 finding out about non-deterministic package builds (@pxref{Invoking guix
1761 challenge}). Similarly, the @option{--check} option of @command{guix
1762 build} allows users to check whether previously-installed substitutes
1763 are genuine by rebuilding them locally (@pxref{build-check,
1764 @command{guix build --check}}).
1766 In the future, we want Guix to have support to publish and retrieve
1767 binaries to/from other users, in a peer-to-peer fashion. If you would
1768 like to discuss this project, join us on @email{guix-devel@@gnu.org}.
1771 @node Packages with Multiple Outputs
1772 @section Packages with Multiple Outputs
1774 @cindex multiple-output packages
1775 @cindex package outputs
1777 Often, packages defined in Guix have a single @dfn{output}---i.e., the
1778 source package leads exactly one directory in the store. When running
1779 @command{guix package -i glibc}, one installs the default output of the
1780 GNU libc package; the default output is called @code{out}, but its name
1781 can be omitted as shown in this command. In this particular case, the
1782 default output of @code{glibc} contains all the C header files, shared
1783 libraries, static libraries, Info documentation, and other supporting
1786 Sometimes it is more appropriate to separate the various types of files
1787 produced from a single source package into separate outputs. For
1788 instance, the GLib C library (used by GTK+ and related packages)
1789 installs more than 20 MiB of reference documentation as HTML pages.
1790 To save space for users who do not need it, the documentation goes to a
1791 separate output, called @code{doc}. To install the main GLib output,
1792 which contains everything but the documentation, one would run:
1795 guix package -i glib
1798 The command to install its documentation is:
1801 guix package -i glib:doc
1804 Some packages install programs with different ``dependency footprints''.
1805 For instance, the WordNet package install both command-line tools and
1806 graphical user interfaces (GUIs). The former depend solely on the C
1807 library, whereas the latter depend on Tcl/Tk and the underlying X
1808 libraries. In this case, we leave the command-line tools in the default
1809 output, whereas the GUIs are in a separate output. This allows users
1810 who do not need the GUIs to save space. The @command{guix size} command
1811 can help find out about such situations (@pxref{Invoking guix size}).
1812 @command{guix graph} can also be helpful (@pxref{Invoking guix graph}).
1814 There are several such multiple-output packages in the GNU distribution.
1815 Other conventional output names include @code{lib} for libraries and
1816 possibly header files, @code{bin} for stand-alone programs, and
1817 @code{debug} for debugging information (@pxref{Installing Debugging
1818 Files}). The outputs of a packages are listed in the third column of
1819 the output of @command{guix package --list-available} (@pxref{Invoking
1823 @node Invoking guix gc
1824 @section Invoking @command{guix gc}
1826 @cindex garbage collector
1827 Packages that are installed but not used may be @dfn{garbage-collected}.
1828 The @command{guix gc} command allows users to explicitly run the garbage
1829 collector to reclaim space from the @file{/gnu/store} directory. It is
1830 the @emph{only} way to remove files from @file{/gnu/store}---removing
1831 files or directories manually may break it beyond repair!
1833 The garbage collector has a set of known @dfn{roots}: any file under
1834 @file{/gnu/store} reachable from a root is considered @dfn{live} and
1835 cannot be deleted; any other file is considered @dfn{dead} and may be
1836 deleted. The set of garbage collector roots includes default user
1837 profiles, and may be augmented with @command{guix build --root}, for
1838 example (@pxref{Invoking guix build}).
1840 Prior to running @code{guix gc --collect-garbage} to make space, it is
1841 often useful to remove old generations from user profiles; that way, old
1842 package builds referenced by those generations can be reclaimed. This
1843 is achieved by running @code{guix package --delete-generations}
1844 (@pxref{Invoking guix package}).
1846 The @command{guix gc} command has three modes of operation: it can be
1847 used to garbage-collect any dead files (the default), to delete specific
1848 files (the @code{--delete} option), to print garbage-collector
1849 information, or for more advanced queries. The garbage collection
1850 options are as follows:
1853 @item --collect-garbage[=@var{min}]
1854 @itemx -C [@var{min}]
1855 Collect garbage---i.e., unreachable @file{/gnu/store} files and
1856 sub-directories. This is the default operation when no option is
1859 When @var{min} is given, stop once @var{min} bytes have been collected.
1860 @var{min} may be a number of bytes, or it may include a unit as a
1861 suffix, such as @code{MiB} for mebibytes and @code{GB} for gigabytes
1862 (@pxref{Block size, size specifications,, coreutils, GNU Coreutils}).
1864 When @var{min} is omitted, collect all the garbage.
1868 Attempt to delete all the store files and directories specified as
1869 arguments. This fails if some of the files are not in the store, or if
1870 they are still live.
1872 @item --list-failures
1873 List store items corresponding to cached build failures.
1875 This prints nothing unless the daemon was started with
1876 @option{--cache-failures} (@pxref{Invoking guix-daemon,
1877 @option{--cache-failures}}).
1879 @item --clear-failures
1880 Remove the specified store items from the failed-build cache.
1882 Again, this option only makes sense when the daemon is started with
1883 @option{--cache-failures}. Otherwise, it does nothing.
1886 Show the list of dead files and directories still present in the
1887 store---i.e., files and directories no longer reachable from any root.
1890 Show the list of live store files and directories.
1894 In addition, the references among existing store files can be queried:
1900 List the references (respectively, the referrers) of store files given
1906 List the requisites of the store files passed as arguments. Requisites
1907 include the store files themselves, their references, and the references
1908 of these, recursively. In other words, the returned list is the
1909 @dfn{transitive closure} of the store files.
1911 @xref{Invoking guix size}, for a tool to profile the size of an
1912 element's closure. @xref{Invoking guix graph}, for a tool to visualize
1913 the graph of references.
1917 Lastly, the following options allow you to check the integrity of the
1918 store and to control disk usage.
1922 @item --verify[=@var{options}]
1923 @cindex integrity, of the store
1924 @cindex integrity checking
1925 Verify the integrity of the store.
1927 By default, make sure that all the store items marked as valid in the
1928 daemon's database actually exist in @file{/gnu/store}.
1930 When provided, @var{options} must a comma-separated list containing one
1931 or more of @code{contents} and @code{repair}.
1933 When passing @option{--verify=contents}, the daemon will compute the
1934 content hash of each store item and compare it against its hash in the
1935 database. Hash mismatches are reported as data corruptions. Because it
1936 traverses @emph{all the files in the store}, this command can take a
1937 long time, especially on systems with a slow disk drive.
1939 @cindex repairing the store
1940 Using @option{--verify=repair} or @option{--verify=contents,repair}
1941 causes the daemon to try to repair corrupt store items by fetching
1942 substitutes for them (@pxref{Substitutes}). Because repairing is not
1943 atomic, and thus potentially dangerous, it is available only to the
1944 system administrator.
1947 @cindex deduplication
1948 Optimize the store by hard-linking identical files---this is
1949 @dfn{deduplication}.
1951 The daemon performs deduplication after each successful build or archive
1952 import, unless it was started with @code{--disable-deduplication}
1953 (@pxref{Invoking guix-daemon, @code{--disable-deduplication}}). Thus,
1954 this option is primarily useful when the daemon was running with
1955 @code{--disable-deduplication}.
1959 @node Invoking guix pull
1960 @section Invoking @command{guix pull}
1962 Packages are installed or upgraded to the latest version available in
1963 the distribution currently available on your local machine. To update
1964 that distribution, along with the Guix tools, you must run @command{guix
1965 pull}: the command downloads the latest Guix source code and package
1966 descriptions, and deploys it.
1968 On completion, @command{guix package} will use packages and package
1969 versions from this just-retrieved copy of Guix. Not only that, but all
1970 the Guix commands and Scheme modules will also be taken from that latest
1971 version. New @command{guix} sub-commands added by the update also
1972 become available@footnote{Under the hood, @command{guix pull} updates
1973 the @file{~/.config/guix/latest} symbolic link to point to the latest
1974 Guix, and the @command{guix} command loads code from there.}.
1976 The @command{guix pull} command is usually invoked with no arguments,
1977 but it supports the following options:
1981 Produce verbose output, writing build logs to the standard error output.
1983 @item --url=@var{url}
1984 Download the source tarball of Guix from @var{url}.
1986 By default, the tarball is taken from its canonical address at
1987 @code{gnu.org}, for the stable branch of Guix.
1990 Use the bootstrap Guile to build the latest Guix. This option is only
1991 useful to Guix developers.
1995 @node Invoking guix archive
1996 @section Invoking @command{guix archive}
1998 The @command{guix archive} command allows users to @dfn{export} files
1999 from the store into a single archive, and to later @dfn{import} them.
2000 In particular, it allows store files to be transferred from one machine
2001 to another machine's store. For example, to transfer the @code{emacs}
2002 package to a machine connected over SSH, one would run:
2005 guix archive --export -r emacs | ssh the-machine guix archive --import
2009 Similarly, a complete user profile may be transferred from one machine
2010 to another like this:
2013 guix archive --export -r $(readlink -f ~/.guix-profile) | \
2014 ssh the-machine guix-archive --import
2018 However, note that, in both examples, all of @code{emacs} and the
2019 profile as well as all of their dependencies are transferred (due to
2020 @code{-r}), regardless of what is already available in the target
2021 machine's store. The @code{--missing} option can help figure out which
2022 items are missing from the target's store.
2024 Archives are stored in the ``Nix archive'' or ``Nar'' format, which is
2025 comparable in spirit to `tar', but with a few noteworthy differences
2026 that make it more appropriate for our purposes. First, rather than
2027 recording all Unix meta-data for each file, the Nar format only mentions
2028 the file type (regular, directory, or symbolic link); Unix permissions
2029 and owner/group are dismissed. Second, the order in which directory
2030 entries are stored always follows the order of file names according to
2031 the C locale collation order. This makes archive production fully
2034 When exporting, the daemon digitally signs the contents of the archive,
2035 and that digital signature is appended. When importing, the daemon
2036 verifies the signature and rejects the import in case of an invalid
2037 signature or if the signing key is not authorized.
2038 @c FIXME: Add xref to daemon doc about signatures.
2040 The main options are:
2044 Export the specified store files or packages (see below.) Write the
2045 resulting archive to the standard output.
2047 Dependencies are @emph{not} included in the output, unless
2048 @code{--recursive} is passed.
2052 When combined with @code{--export}, this instructs @command{guix
2053 archive} to include dependencies of the given items in the archive.
2054 Thus, the resulting archive is self-contained: it contains the closure
2055 of the exported store items.
2058 Read an archive from the standard input, and import the files listed
2059 therein into the store. Abort if the archive has an invalid digital
2060 signature, or if it is signed by a public key not among the authorized
2061 keys (see @code{--authorize} below.)
2064 Read a list of store file names from the standard input, one per line,
2065 and write on the standard output the subset of these files missing from
2068 @item --generate-key[=@var{parameters}]
2069 @cindex signing, archives
2070 Generate a new key pair for the daemons. This is a prerequisite before
2071 archives can be exported with @code{--export}. Note that this operation
2072 usually takes time, because it needs to gather enough entropy to
2073 generate the key pair.
2075 The generated key pair is typically stored under @file{/etc/guix}, in
2076 @file{signing-key.pub} (public key) and @file{signing-key.sec} (private
2077 key, which must be kept secret.) When @var{parameters} is omitted,
2078 an ECDSA key using the Ed25519 curve is generated, or, for Libgcrypt
2079 versions before 1.6.0, it is a 4096-bit RSA key.
2080 Alternately, @var{parameters} can specify
2081 @code{genkey} parameters suitable for Libgcrypt (@pxref{General
2082 public-key related Functions, @code{gcry_pk_genkey},, gcrypt, The
2083 Libgcrypt Reference Manual}).
2086 @cindex authorizing, archives
2087 Authorize imports signed by the public key passed on standard input.
2088 The public key must be in ``s-expression advanced format''---i.e., the
2089 same format as the @file{signing-key.pub} file.
2091 The list of authorized keys is kept in the human-editable file
2092 @file{/etc/guix/acl}. The file contains
2093 @url{http://people.csail.mit.edu/rivest/Sexp.txt, ``advanced-format
2094 s-expressions''} and is structured as an access-control list in the
2095 @url{http://theworld.com/~cme/spki.txt, Simple Public-Key Infrastructure
2098 @item --extract=@var{directory}
2099 @itemx -x @var{directory}
2100 Read a single-item archive as served by substitute servers
2101 (@pxref{Substitutes}) and extract it to @var{directory}. This is a
2102 low-level operation needed in only very narrow use cases; see below.
2104 For example, the following command extracts the substitute for Emacs
2105 served by @code{hydra.gnu.org} to @file{/tmp/emacs}:
2109 http://hydra.gnu.org/nar/@dots{}-emacs-24.5 \
2110 | bunzip2 | guix archive -x /tmp/emacs
2113 Single-item archives are different from multiple-item archives produced
2114 by @command{guix archive --export}; they contain a single store item,
2115 and they do @emph{not} embed a signature. Thus this operation does
2116 @emph{no} signature verification and its output should be considered
2119 The primary purpose of this operation is to facilitate inspection of
2120 archive contents coming from possibly untrusted substitute servers.
2124 To export store files as an archive to the standard output, run:
2127 guix archive --export @var{options} @var{specifications}...
2130 @var{specifications} may be either store file names or package
2131 specifications, as for @command{guix package} (@pxref{Invoking guix
2132 package}). For instance, the following command creates an archive
2133 containing the @code{gui} output of the @code{git} package and the main
2134 output of @code{emacs}:
2137 guix archive --export git:gui /gnu/store/...-emacs-24.3 > great.nar
2140 If the specified packages are not built yet, @command{guix archive}
2141 automatically builds them. The build process may be controlled with the
2142 common build options (@pxref{Common Build Options}).
2144 @c *********************************************************************
2147 @c *********************************************************************
2148 @node Programming Interface
2149 @chapter Programming Interface
2151 GNU Guix provides several Scheme programming interfaces (APIs) to
2152 define, build, and query packages. The first interface allows users to
2153 write high-level package definitions. These definitions refer to
2154 familiar packaging concepts, such as the name and version of a package,
2155 its build system, and its dependencies. These definitions can then be
2156 turned into concrete build actions.
2158 Build actions are performed by the Guix daemon, on behalf of users. In a
2159 standard setup, the daemon has write access to the store---the
2160 @file{/gnu/store} directory---whereas users do not. The recommended
2161 setup also has the daemon perform builds in chroots, under a specific
2162 build users, to minimize interference with the rest of the system.
2165 Lower-level APIs are available to interact with the daemon and the
2166 store. To instruct the daemon to perform a build action, users actually
2167 provide it with a @dfn{derivation}. A derivation is a low-level
2168 representation of the build actions to be taken, and the environment in
2169 which they should occur---derivations are to package definitions what
2170 assembly is to C programs. The term ``derivation'' comes from the fact
2171 that build results @emph{derive} from them.
2173 This chapter describes all these APIs in turn, starting from high-level
2174 package definitions.
2177 * Defining Packages:: Defining new packages.
2178 * Build Systems:: Specifying how packages are built.
2179 * The Store:: Manipulating the package store.
2180 * Derivations:: Low-level interface to package derivations.
2181 * The Store Monad:: Purely functional interface to the store.
2182 * G-Expressions:: Manipulating build expressions.
2185 @node Defining Packages
2186 @section Defining Packages
2188 The high-level interface to package definitions is implemented in the
2189 @code{(guix packages)} and @code{(guix build-system)} modules. As an
2190 example, the package definition, or @dfn{recipe}, for the GNU Hello
2191 package looks like this:
2194 (define-module (gnu packages hello)
2195 #:use-module (guix packages)
2196 #:use-module (guix download)
2197 #:use-module (guix build-system gnu)
2198 #:use-module (guix licenses)
2199 #:use-module (gnu packages gawk))
2201 (define-public hello
2207 (uri (string-append "mirror://gnu/hello/hello-" version
2211 "0ssi1wpaf7plaswqqjwigppsg5fyh99vdlb9kzl7c9lng89ndq1i"))))
2212 (build-system gnu-build-system)
2213 (arguments `(#:configure-flags '("--enable-silent-rules")))
2214 (inputs `(("gawk" ,gawk)))
2215 (synopsis "Hello, GNU world: An example GNU package")
2216 (description "Guess what GNU Hello prints!")
2217 (home-page "http://www.gnu.org/software/hello/")
2222 Without being a Scheme expert, the reader may have guessed the meaning
2223 of the various fields here. This expression binds variable @code{hello}
2224 to a @code{<package>} object, which is essentially a record
2225 (@pxref{SRFI-9, Scheme records,, guile, GNU Guile Reference Manual}).
2226 This package object can be inspected using procedures found in the
2227 @code{(guix packages)} module; for instance, @code{(package-name hello)}
2228 returns---surprise!---@code{"hello"}.
2230 With luck, you may be able to import part or all of the definition of
2231 the package you are interested in from another repository, using the
2232 @code{guix import} command (@pxref{Invoking guix import}).
2234 In the example above, @var{hello} is defined into a module of its own,
2235 @code{(gnu packages hello)}. Technically, this is not strictly
2236 necessary, but it is convenient to do so: all the packages defined in
2237 modules under @code{(gnu packages @dots{})} are automatically known to
2238 the command-line tools (@pxref{Package Modules}).
2240 There are a few points worth noting in the above package definition:
2244 The @code{source} field of the package is an @code{<origin>} object
2245 (@pxref{origin Reference}, for the complete reference).
2246 Here, the @code{url-fetch} method from @code{(guix download)} is used,
2247 meaning that the source is a file to be downloaded over FTP or HTTP.
2249 The @code{mirror://gnu} prefix instructs @code{url-fetch} to use one of
2250 the GNU mirrors defined in @code{(guix download)}.
2252 The @code{sha256} field specifies the expected SHA256 hash of the file
2253 being downloaded. It is mandatory, and allows Guix to check the
2254 integrity of the file. The @code{(base32 @dots{})} form introduces the
2255 base32 representation of the hash. You can obtain this information with
2256 @code{guix download} (@pxref{Invoking guix download}) and @code{guix
2257 hash} (@pxref{Invoking guix hash}).
2260 When needed, the @code{origin} form can also have a @code{patches} field
2261 listing patches to be applied, and a @code{snippet} field giving a
2262 Scheme expression to modify the source code.
2265 @cindex GNU Build System
2266 The @code{build-system} field specifies the procedure to build the
2267 package (@pxref{Build Systems}). Here, @var{gnu-build-system}
2268 represents the familiar GNU Build System, where packages may be
2269 configured, built, and installed with the usual @code{./configure &&
2270 make && make check && make install} command sequence.
2273 The @code{arguments} field specifies options for the build system
2274 (@pxref{Build Systems}). Here it is interpreted by
2275 @var{gnu-build-system} as a request run @file{configure} with the
2276 @code{--enable-silent-rules} flag.
2279 The @code{inputs} field specifies inputs to the build process---i.e.,
2280 build-time or run-time dependencies of the package. Here, we define an
2281 input called @code{"gawk"} whose value is that of the @var{gawk}
2282 variable; @var{gawk} is itself bound to a @code{<package>} object.
2284 Note that GCC, Coreutils, Bash, and other essential tools do not need to
2285 be specified as inputs here. Instead, @var{gnu-build-system} takes care
2286 of ensuring that they are present (@pxref{Build Systems}).
2288 However, any other dependencies need to be specified in the
2289 @code{inputs} field. Any dependency not specified here will simply be
2290 unavailable to the build process, possibly leading to a build failure.
2293 @xref{package Reference}, for a full description of possible fields.
2295 Once a package definition is in place, the
2296 package may actually be built using the @code{guix build} command-line
2297 tool (@pxref{Invoking guix build}). You can easily jump back to the
2298 package definition using the @command{guix edit} command
2299 (@pxref{Invoking guix edit}).
2300 @xref{Packaging Guidelines}, for
2301 more information on how to test package definitions, and
2302 @ref{Invoking guix lint}, for information on how to check a definition
2303 for style conformance.
2305 Eventually, updating the package definition to a new upstream version
2306 can be partly automated by the @command{guix refresh} command
2307 (@pxref{Invoking guix refresh}).
2309 Behind the scenes, a derivation corresponding to the @code{<package>}
2310 object is first computed by the @code{package-derivation} procedure.
2311 That derivation is stored in a @code{.drv} file under @file{/gnu/store}.
2312 The build actions it prescribes may then be realized by using the
2313 @code{build-derivations} procedure (@pxref{The Store}).
2315 @deffn {Scheme Procedure} package-derivation @var{store} @var{package} [@var{system}]
2316 Return the @code{<derivation>} object of @var{package} for @var{system}
2317 (@pxref{Derivations}).
2319 @var{package} must be a valid @code{<package>} object, and @var{system}
2320 must be a string denoting the target system type---e.g.,
2321 @code{"x86_64-linux"} for an x86_64 Linux-based GNU system. @var{store}
2322 must be a connection to the daemon, which operates on the store
2323 (@pxref{The Store}).
2327 @cindex cross-compilation
2328 Similarly, it is possible to compute a derivation that cross-builds a
2329 package for some other system:
2331 @deffn {Scheme Procedure} package-cross-derivation @var{store} @
2332 @var{package} @var{target} [@var{system}]
2333 Return the @code{<derivation>} object of @var{package} cross-built from
2334 @var{system} to @var{target}.
2336 @var{target} must be a valid GNU triplet denoting the target hardware
2337 and operating system, such as @code{"mips64el-linux-gnu"}
2338 (@pxref{Configuration Names, GNU configuration triplets,, configure, GNU
2339 Configure and Build System}).
2343 * package Reference :: The package data type.
2344 * origin Reference:: The origin data type.
2348 @node package Reference
2349 @subsection @code{package} Reference
2351 This section summarizes all the options available in @code{package}
2352 declarations (@pxref{Defining Packages}).
2354 @deftp {Data Type} package
2355 This is the data type representing a package recipe.
2359 The name of the package, as a string.
2361 @item @code{version}
2362 The version of the package, as a string.
2365 An origin object telling how the source code for the package should be
2366 acquired (@pxref{origin Reference}).
2368 @item @code{build-system}
2369 The build system that should be used to build the package (@pxref{Build
2372 @item @code{arguments} (default: @code{'()})
2373 The arguments that should be passed to the build system. This is a
2374 list, typically containing sequential keyword-value pairs.
2376 @item @code{inputs} (default: @code{'()})
2377 @itemx @code{native-inputs} (default: @code{'()})
2378 @itemx @code{propagated-inputs} (default: @code{'()})
2379 @cindex inputs, of packages
2380 These fields list dependencies of the package. Each one is a list of
2381 tuples, where each tuple has a label for the input (a string) as its
2382 first element, a package, origin, or derivation as its second element,
2383 and optionally the name of the output thereof that should be used, which
2384 defaults to @code{"out"} (@pxref{Packages with Multiple Outputs}, for
2385 more on package outputs). For example, the list below specifies 3
2389 `(("libffi" ,libffi)
2390 ("libunistring" ,libunistring)
2391 ("glib:bin" ,glib "bin")) ;the "bin" output of Glib
2394 @cindex cross compilation, package dependencies
2395 The distinction between @code{native-inputs} and @code{inputs} is
2396 necessary when considering cross-compilation. When cross-compiling,
2397 dependencies listed in @code{inputs} are built for the @emph{target}
2398 architecture; conversely, dependencies listed in @code{native-inputs}
2399 are built for the architecture of the @emph{build} machine.
2401 @code{native-inputs} is typically where you would list tools needed at
2402 build time but not at run time, such as Autoconf, Automake, pkg-config,
2403 Gettext, or Bison. @command{guix lint} can report likely mistakes in
2404 this area (@pxref{Invoking guix lint}).
2406 @anchor{package-propagated-inputs}
2407 Lastly, @code{propagated-inputs} is similar to @code{inputs}, but the
2408 specified packages will be force-installed alongside the package they
2409 belong to (@pxref{package-cmd-propagated-inputs, @command{guix
2410 package}}, for information on how @command{guix package} deals with
2413 For example this is necessary when a C/C++ library needs headers of
2414 another library to compile, or when a pkg-config file refers to another
2415 one @i{via} its @code{Requires} field.
2417 Another example where @code{propagated-inputs} is useful is for
2418 languages that lack a facility to record the run-time search path akin
2419 to ELF's @code{RUNPATH}; this includes Guile, Python, Perl, GHC, and
2420 more. To ensure that libraries written in those languages can find
2421 library code they depend on at run time, run-time dependencies must be
2422 listed in @code{propagated-inputs} rather than @code{inputs}.
2424 @item @code{self-native-input?} (default: @code{#f})
2425 This is a Boolean field telling whether the package should use itself as
2426 a native input when cross-compiling.
2428 @item @code{outputs} (default: @code{'("out")})
2429 The list of output names of the package. @xref{Packages with Multiple
2430 Outputs}, for typical uses of additional outputs.
2432 @item @code{native-search-paths} (default: @code{'()})
2433 @itemx @code{search-paths} (default: @code{'()})
2434 A list of @code{search-path-specification} objects describing
2435 search-path environment variables honored by the package.
2437 @item @code{replacement} (default: @code{#f})
2438 This must either @code{#f} or a package object that will be used as a
2439 @dfn{replacement} for this package. @xref{Security Updates, grafts},
2442 @item @code{synopsis}
2443 A one-line description of the package.
2445 @item @code{description}
2446 A more elaborate description of the package.
2448 @item @code{license}
2449 The license of the package; a value from @code{(guix licenses)}.
2451 @item @code{home-page}
2452 The URL to the home-page of the package, as a string.
2454 @item @code{supported-systems} (default: @var{%supported-systems})
2455 The list of systems supported by the package, as strings of the form
2456 @code{architecture-kernel}, for example @code{"x86_64-linux"}.
2458 @item @code{maintainers} (default: @code{'()})
2459 The list of maintainers of the package, as @code{maintainer} objects.
2461 @item @code{location} (default: source location of the @code{package} form)
2462 The source location of the package. It's useful to override this when
2463 inheriting from another package, in which case this field is not
2464 automatically corrected.
2469 @node origin Reference
2470 @subsection @code{origin} Reference
2472 This section summarizes all the options available in @code{origin}
2473 declarations (@pxref{Defining Packages}).
2475 @deftp {Data Type} origin
2476 This is the data type representing a source code origin.
2480 An object containing the URI of the source. The object type depends on
2481 the @code{method} (see below). For example, when using the
2482 @var{url-fetch} method of @code{(guix download)}, the valid @code{uri}
2483 values are: a URL represented as a string, or a list thereof.
2486 A procedure that will handle the URI.
2491 @item @var{url-fetch} from @code{(guix download)}
2492 download a file the HTTP, HTTPS, or FTP URL specified in the
2495 @item @var{git-fetch} from @code{(guix git-download)}
2496 clone the Git version control repository, and check out the revision
2497 specified in the @code{uri} field as a @code{git-reference} object; a
2498 @code{git-reference} looks like this:
2502 (url "git://git.debian.org/git/pkg-shadow/shadow")
2503 (commit "v4.1.5.1"))
2508 A bytevector containing the SHA-256 hash of the source. Typically the
2509 @code{base32} form is used here to generate the bytevector from a
2512 @item @code{file-name} (default: @code{#f})
2513 The file name under which the source code should be saved. When this is
2514 @code{#f}, a sensible default value will be used in most cases. In case
2515 the source is fetched from a URL, the file name from the URL will be
2516 used. For version control checkouts, it's recommended to provide the
2517 file name explicitly because the default is not very descriptive.
2519 @item @code{patches} (default: @code{'()})
2520 A list of file names containing patches to be applied to the source.
2522 @item @code{snippet} (default: @code{#f})
2523 A quoted piece of code that will be run in the source directory to make
2524 any modifications, which is sometimes more convenient than a patch.
2526 @item @code{patch-flags} (default: @code{'("-p1")})
2527 A list of command-line flags that should be passed to the @code{patch}
2530 @item @code{patch-inputs} (default: @code{#f})
2531 Input packages or derivations to the patching process. When this is
2532 @code{#f}, the usual set of inputs necessary for patching are provided,
2533 such as GNU@tie{}Patch.
2535 @item @code{modules} (default: @code{'()})
2536 A list of Guile modules that should be loaded during the patching
2537 process and while running the code in the @code{snippet} field.
2539 @item @code{imported-modules} (default: @code{'()})
2540 The list of Guile modules to import in the patch derivation, for use by
2543 @item @code{patch-guile} (default: @code{#f})
2544 The Guile package that should be used in the patching process. When
2545 this is @code{#f}, a sensible default is used.
2551 @section Build Systems
2553 @cindex build system
2554 Each package definition specifies a @dfn{build system} and arguments for
2555 that build system (@pxref{Defining Packages}). This @code{build-system}
2556 field represents the build procedure of the package, as well implicit
2557 dependencies of that build procedure.
2559 Build systems are @code{<build-system>} objects. The interface to
2560 create and manipulate them is provided by the @code{(guix build-system)}
2561 module, and actual build systems are exported by specific modules.
2563 @cindex bag (low-level package representation)
2564 Under the hood, build systems first compile package objects to
2565 @dfn{bags}. A @dfn{bag} is like a package, but with less
2566 ornamentation---in other words, a bag is a lower-level representation of
2567 a package, which includes all the inputs of that package, including some
2568 that were implicitly added by the build system. This intermediate
2569 representation is then compiled to a derivation (@pxref{Derivations}).
2571 Build systems accept an optional list of @dfn{arguments}. In package
2572 definitions, these are passed @i{via} the @code{arguments} field
2573 (@pxref{Defining Packages}). They are typically keyword arguments
2574 (@pxref{Optional Arguments, keyword arguments in Guile,, guile, GNU
2575 Guile Reference Manual}). The value of these arguments is usually
2576 evaluated in the @dfn{build stratum}---i.e., by a Guile process launched
2577 by the daemon (@pxref{Derivations}).
2579 The main build system is @var{gnu-build-system}, which implements the
2580 standard build procedure for GNU packages and many other packages. It
2581 is provided by the @code{(guix build-system gnu)} module.
2583 @defvr {Scheme Variable} gnu-build-system
2584 @var{gnu-build-system} represents the GNU Build System, and variants
2585 thereof (@pxref{Configuration, configuration and makefile conventions,,
2586 standards, GNU Coding Standards}).
2588 @cindex build phases
2589 In a nutshell, packages using it configured, built, and installed with
2590 the usual @code{./configure && make && make check && make install}
2591 command sequence. In practice, a few additional steps are often needed.
2592 All these steps are split up in separate @dfn{phases},
2593 notably@footnote{Please see the @code{(guix build gnu-build-system)}
2594 modules for more details about the build phases.}:
2598 Unpack the source tarball, and change the current directory to the
2599 extracted source tree. If the source is actually a directory, copy it
2600 to the build tree, and enter that directory.
2602 @item patch-source-shebangs
2603 Patch shebangs encountered in source files so they refer to the right
2604 store file names. For instance, this changes @code{#!/bin/sh} to
2605 @code{#!/gnu/store/@dots{}-bash-4.3/bin/sh}.
2608 Run the @file{configure} script with a number of default options, such
2609 as @code{--prefix=/gnu/store/@dots{}}, as well as the options specified
2610 by the @code{#:configure-flags} argument.
2613 Run @code{make} with the list of flags specified with
2614 @code{#:make-flags}. If the @code{#:parallel-build?} argument is true
2615 (the default), build with @code{make -j}.
2618 Run @code{make check}, or some other target specified with
2619 @code{#:test-target}, unless @code{#:tests? #f} is passed. If the
2620 @code{#:parallel-tests?} argument is true (the default), run @code{make
2624 Run @code{make install} with the flags listed in @code{#:make-flags}.
2626 @item patch-shebangs
2627 Patch shebangs on the installed executable files.
2630 Strip debugging symbols from ELF files (unless @code{#:strip-binaries?}
2631 is false), copying them to the @code{debug} output when available
2632 (@pxref{Installing Debugging Files}).
2635 @vindex %standard-phases
2636 The build-side module @code{(guix build gnu-build-system)} defines
2637 @var{%standard-phases} as the default list of build phases.
2638 @var{%standard-phases} is a list of symbol/procedure pairs, where the
2639 procedure implements the actual phase.
2641 The list of phases used for a particular package can be changed with the
2642 @code{#:phases} parameter. For instance, passing:
2645 #:phases (alist-delete 'configure %standard-phases)
2648 means that all the phases described above will be used, except the
2649 @code{configure} phase.
2651 In addition, this build system ensures that the ``standard'' environment
2652 for GNU packages is available. This includes tools such as GCC, libc,
2653 Coreutils, Bash, Make, Diffutils, grep, and sed (see the @code{(guix
2654 build-system gnu)} module for a complete list.) We call these the
2655 @dfn{implicit inputs} of a package, because package definitions don't
2656 have to mention them.
2659 Other @code{<build-system>} objects are defined to support other
2660 conventions and tools used by free software packages. They inherit most
2661 of @var{gnu-build-system}, and differ mainly in the set of inputs
2662 implicitly added to the build process, and in the list of phases
2663 executed. Some of these build systems are listed below.
2665 @defvr {Scheme Variable} cmake-build-system
2666 This variable is exported by @code{(guix build-system cmake)}. It
2667 implements the build procedure for packages using the
2668 @url{http://www.cmake.org, CMake build tool}.
2670 It automatically adds the @code{cmake} package to the set of inputs.
2671 Which package is used can be specified with the @code{#:cmake}
2674 The @code{#:configure-flags} parameter is taken as a list of flags
2675 passed to the @command{cmake} command. The @code{#:build-type}
2676 parameter specifies in abstract terms the flags passed to the compiler;
2677 it defaults to @code{"RelWithDebInfo"} (short for ``release mode with
2678 debugging information''), which roughly means that code is compiled with
2679 @code{-O2 -g}, as is the case for Autoconf-based packages by default.
2682 @defvr {Scheme Variable} glib-or-gtk-build-system
2683 This variable is exported by @code{(guix build-system glib-or-gtk)}. It
2684 is intended for use with packages making use of GLib or GTK+.
2686 This build system adds the following two phases to the ones defined by
2687 @var{gnu-build-system}:
2690 @item glib-or-gtk-wrap
2691 The phase @code{glib-or-gtk-wrap} ensures that programs found under
2692 @file{bin/} are able to find GLib's ``schemas'' and
2693 @uref{https://developer.gnome.org/gtk3/stable/gtk-running.html, GTK+
2694 modules}. This is achieved by wrapping the programs in launch scripts
2695 that appropriately set the @code{XDG_DATA_DIRS} and @code{GTK_PATH}
2696 environment variables.
2698 It is possible to exclude specific package outputs from that wrapping
2699 process by listing their names in the
2700 @code{#:glib-or-gtk-wrap-excluded-outputs} parameter. This is useful
2701 when an output is known not to contain any GLib or GTK+ binaries, and
2702 where wrapping would gratuitously add a dependency of that output on
2705 @item glib-or-gtk-compile-schemas
2706 The phase @code{glib-or-gtk-compile-schemas} makes sure that all GLib's
2707 @uref{https://developer.gnome.org/gio/stable/glib-compile-schemas.html,
2708 GSettings schemas} are compiled. Compilation is performed by the
2709 @command{glib-compile-schemas} program. It is provided by the package
2710 @code{glib:bin} which is automatically imported by the build system.
2711 The @code{glib} package providing @command{glib-compile-schemas} can be
2712 specified with the @code{#:glib} parameter.
2715 Both phases are executed after the @code{install} phase.
2718 @defvr {Scheme Variable} python-build-system
2719 This variable is exported by @code{(guix build-system python)}. It
2720 implements the more or less standard build procedure used by Python
2721 packages, which consists in running @code{python setup.py build} and
2722 then @code{python setup.py install --prefix=/gnu/store/@dots{}}.
2724 For packages that install stand-alone Python programs under @code{bin/},
2725 it takes care of wrapping these programs so their @code{PYTHONPATH}
2726 environment variable points to all the Python libraries they depend on.
2728 Which Python package is used can be specified with the @code{#:python}
2732 @defvr {Scheme Variable} perl-build-system
2733 This variable is exported by @code{(guix build-system perl)}. It
2734 implements the standard build procedure for Perl packages, which either
2735 consists in running @code{perl Build.PL --prefix=/gnu/store/@dots{}},
2736 followed by @code{Build} and @code{Build install}; or in running
2737 @code{perl Makefile.PL PREFIX=/gnu/store/@dots{}}, followed by
2738 @code{make} and @code{make install}; depending on which of
2739 @code{Build.PL} or @code{Makefile.PL} is present in the package
2740 distribution. Preference is given to the former if both @code{Build.PL}
2741 and @code{Makefile.PL} exist in the package distribution. This
2742 preference can be reversed by specifying @code{#t} for the
2743 @code{#:make-maker?} parameter.
2745 The initial @code{perl Makefile.PL} or @code{perl Build.PL} invocation
2746 passes flags specified by the @code{#:make-maker-flags} or
2747 @code{#:module-build-flags} parameter, respectively.
2749 Which Perl package is used can be specified with @code{#:perl}.
2752 @defvr {Scheme Variable} r-build-system
2753 This variable is exported by @code{(guix build-system r)}. It
2754 implements the build procedure used by @uref{http://r-project.org, R}
2755 packages, which essentially is little more than running @code{R CMD
2756 INSTALL --library=/gnu/store/@dots{}} in an environment where
2757 @code{R_LIBS_SITE} contains the paths to all R package inputs. Tests
2758 are run after installation using the R function
2759 @code{tools::testInstalledPackage}.
2762 @defvr {Scheme Variable} ruby-build-system
2763 This variable is exported by @code{(guix build-system ruby)}. It
2764 implements the RubyGems build procedure used by Ruby packages, which
2765 involves running @code{gem build} followed by @code{gem install}.
2767 The @code{source} field of a package that uses this build system
2768 typically references a gem archive, since this is the format that Ruby
2769 developers use when releasing their software. The build system unpacks
2770 the gem archive, potentially patches the source, runs the test suite,
2771 repackages the gem, and installs it. Additionally, directories and
2772 tarballs may be referenced to allow building unreleased gems from Git or
2773 a traditional source release tarball.
2775 Which Ruby package is used can be specified with the @code{#:ruby}
2776 parameter. A list of additional flags to be passed to the @command{gem}
2777 command can be specified with the @code{#:gem-flags} parameter.
2780 @defvr {Scheme Variable} waf-build-system
2781 This variable is exported by @code{(guix build-system waf)}. It
2782 implements a build procedure around the @code{waf} script. The common
2783 phases---@code{configure}, @code{build}, and @code{install}---are
2784 implemented by passing their names as arguments to the @code{waf}
2787 The @code{waf} script is executed by the Python interpreter. Which
2788 Python package is used to run the script can be specified with the
2789 @code{#:python} parameter.
2792 @defvr {Scheme Variable} haskell-build-system
2793 This variable is exported by @code{(guix build-system haskell)}. It
2794 implements the Cabal build procedure used by Haskell packages, which
2795 involves running @code{runhaskell Setup.hs configure
2796 --prefix=/gnu/store/@dots{}} and @code{runhaskell Setup.hs build}.
2797 Instead of installing the package by running @code{runhaskell Setup.hs
2798 install}, to avoid trying to register libraries in the read-only
2799 compiler store directory, the build system uses @code{runhaskell
2800 Setup.hs copy}, followed by @code{runhaskell Setup.hs register}. In
2801 addition, the build system generates the package documentation by
2802 running @code{runhaskell Setup.hs haddock}, unless @code{#:haddock? #f}
2803 is passed. Optional Haddock parameters can be passed with the help of
2804 the @code{#:haddock-flags} parameter. If the file @code{Setup.hs} is
2805 not found, the build system looks for @code{Setup.lhs} instead.
2807 Which Haskell compiler is used can be specified with the @code{#:haskell}
2808 parameter which defaults to @code{ghc}.
2811 @defvr {Scheme Variable} emacs-build-system
2812 This variable is exported by @code{(guix build-system emacs)}. It
2813 implements an installation procedure similar to the one of Emacs' own
2814 packaging system (@pxref{Packages,,, emacs, The GNU Emacs Manual}).
2816 It first creates the @code{@var{package}-autoloads.el} file, then it
2817 byte compiles all Emacs Lisp files. Differently from the Emacs
2818 packaging system, the Info documentation files are moved to the standard
2819 documentation directory and the @file{dir} file is deleted. Each
2820 package is installed in its own directory under
2821 @file{share/emacs/site-lisp/guix.d}.
2824 Lastly, for packages that do not need anything as sophisticated, a
2825 ``trivial'' build system is provided. It is trivial in the sense that
2826 it provides basically no support: it does not pull any implicit inputs,
2827 and does not have a notion of build phases.
2829 @defvr {Scheme Variable} trivial-build-system
2830 This variable is exported by @code{(guix build-system trivial)}.
2832 This build system requires a @code{#:builder} argument. This argument
2833 must be a Scheme expression that builds the package's output(s)---as
2834 with @code{build-expression->derivation} (@pxref{Derivations,
2835 @code{build-expression->derivation}}).
2844 Conceptually, the @dfn{store} is where derivations that have been
2845 successfully built are stored---by default, under @file{/gnu/store}.
2846 Sub-directories in the store are referred to as @dfn{store paths}. The
2847 store has an associated database that contains information such as the
2848 store paths referred to by each store path, and the list of @emph{valid}
2849 store paths---paths that result from a successful build.
2851 The store is always accessed by the daemon on behalf of its clients
2852 (@pxref{Invoking guix-daemon}). To manipulate the store, clients
2853 connect to the daemon over a Unix-domain socket, send it requests, and
2854 read the result---these are remote procedure calls, or RPCs.
2856 The @code{(guix store)} module provides procedures to connect to the
2857 daemon, and to perform RPCs. These are described below.
2859 @deffn {Scheme Procedure} open-connection [@var{file}] [#:reserve-space? #t]
2860 Connect to the daemon over the Unix-domain socket at @var{file}. When
2861 @var{reserve-space?} is true, instruct it to reserve a little bit of
2862 extra space on the file system so that the garbage collector can still
2863 operate, should the disk become full. Return a server object.
2865 @var{file} defaults to @var{%default-socket-path}, which is the normal
2866 location given the options that were passed to @command{configure}.
2869 @deffn {Scheme Procedure} close-connection @var{server}
2870 Close the connection to @var{server}.
2873 @defvr {Scheme Variable} current-build-output-port
2874 This variable is bound to a SRFI-39 parameter, which refers to the port
2875 where build and error logs sent by the daemon should be written.
2878 Procedures that make RPCs all take a server object as their first
2881 @deffn {Scheme Procedure} valid-path? @var{server} @var{path}
2882 Return @code{#t} when @var{path} is a valid store path.
2885 @deffn {Scheme Procedure} add-text-to-store @var{server} @var{name} @var{text} [@var{references}]
2886 Add @var{text} under file @var{name} in the store, and return its store
2887 path. @var{references} is the list of store paths referred to by the
2888 resulting store path.
2891 @deffn {Scheme Procedure} build-derivations @var{server} @var{derivations}
2892 Build @var{derivations} (a list of @code{<derivation>} objects or
2893 derivation paths), and return when the worker is done building them.
2894 Return @code{#t} on success.
2897 Note that the @code{(guix monads)} module provides a monad as well as
2898 monadic versions of the above procedures, with the goal of making it
2899 more convenient to work with code that accesses the store (@pxref{The
2903 @i{This section is currently incomplete.}
2906 @section Derivations
2909 Low-level build actions and the environment in which they are performed
2910 are represented by @dfn{derivations}. A derivation contain the
2911 following pieces of information:
2915 The outputs of the derivation---derivations produce at least one file or
2916 directory in the store, but may produce more.
2919 The inputs of the derivations, which may be other derivations or plain
2920 files in the store (patches, build scripts, etc.)
2923 The system type targeted by the derivation---e.g., @code{x86_64-linux}.
2926 The file name of a build script in the store, along with the arguments
2930 A list of environment variables to be defined.
2934 @cindex derivation path
2935 Derivations allow clients of the daemon to communicate build actions to
2936 the store. They exist in two forms: as an in-memory representation,
2937 both on the client- and daemon-side, and as files in the store whose
2938 name end in @code{.drv}---these files are referred to as @dfn{derivation
2939 paths}. Derivations paths can be passed to the @code{build-derivations}
2940 procedure to perform the build actions they prescribe (@pxref{The
2943 The @code{(guix derivations)} module provides a representation of
2944 derivations as Scheme objects, along with procedures to create and
2945 otherwise manipulate derivations. The lowest-level primitive to create
2946 a derivation is the @code{derivation} procedure:
2948 @deffn {Scheme Procedure} derivation @var{store} @var{name} @var{builder} @
2949 @var{args} [#:outputs '("out")] [#:hash #f] [#:hash-algo #f] @
2950 [#:recursive? #f] [#:inputs '()] [#:env-vars '()] @
2951 [#:system (%current-system)] [#:references-graphs #f] @
2952 [#:allowed-references #f] [#:leaked-env-vars #f] [#:local-build? #f] @
2953 [#:substitutable? #t]
2954 Build a derivation with the given arguments, and return the resulting
2955 @code{<derivation>} object.
2957 When @var{hash} and @var{hash-algo} are given, a
2958 @dfn{fixed-output derivation} is created---i.e., one whose result is
2959 known in advance, such as a file download. If, in addition,
2960 @var{recursive?} is true, then that fixed output may be an executable
2961 file or a directory and @var{hash} must be the hash of an archive
2962 containing this output.
2964 When @var{references-graphs} is true, it must be a list of file
2965 name/store path pairs. In that case, the reference graph of each store
2966 path is exported in the build environment in the corresponding file, in
2967 a simple text format.
2969 When @var{allowed-references} is true, it must be a list of store items
2970 or outputs that the derivation's output may refer to.
2972 When @var{leaked-env-vars} is true, it must be a list of strings
2973 denoting environment variables that are allowed to ``leak'' from the
2974 daemon's environment to the build environment. This is only applicable
2975 to fixed-output derivations---i.e., when @var{hash} is true. The main
2976 use is to allow variables such as @code{http_proxy} to be passed to
2977 derivations that download files.
2979 When @var{local-build?} is true, declare that the derivation is not a
2980 good candidate for offloading and should rather be built locally
2981 (@pxref{Daemon Offload Setup}). This is the case for small derivations
2982 where the costs of data transfers would outweigh the benefits.
2984 When @var{substitutable?} is false, declare that substitutes of the
2985 derivation's output should not be used (@pxref{Substitutes}). This is
2986 useful, for instance, when building packages that capture details of the
2987 host CPU instruction set.
2991 Here's an example with a shell script as its builder, assuming
2992 @var{store} is an open connection to the daemon, and @var{bash} points
2993 to a Bash executable in the store:
2996 (use-modules (guix utils)
3000 (let ((builder ; add the Bash script to the store
3001 (add-text-to-store store "my-builder.sh"
3002 "echo hello world > $out\n" '())))
3003 (derivation store "foo"
3004 bash `("-e" ,builder)
3005 #:inputs `((,bash) (,builder))
3006 #:env-vars '(("HOME" . "/homeless"))))
3007 @result{} #<derivation /gnu/store/@dots{}-foo.drv => /gnu/store/@dots{}-foo>
3010 As can be guessed, this primitive is cumbersome to use directly. A
3011 better approach is to write build scripts in Scheme, of course! The
3012 best course of action for that is to write the build code as a
3013 ``G-expression'', and to pass it to @code{gexp->derivation}. For more
3014 information, @pxref{G-Expressions}.
3016 Once upon a time, @code{gexp->derivation} did not exist and constructing
3017 derivations with build code written in Scheme was achieved with
3018 @code{build-expression->derivation}, documented below. This procedure
3019 is now deprecated in favor of the much nicer @code{gexp->derivation}.
3021 @deffn {Scheme Procedure} build-expression->derivation @var{store} @
3022 @var{name} @var{exp} @
3023 [#:system (%current-system)] [#:inputs '()] @
3024 [#:outputs '("out")] [#:hash #f] [#:hash-algo #f] @
3025 [#:recursive? #f] [#:env-vars '()] [#:modules '()] @
3026 [#:references-graphs #f] [#:allowed-references #f] @
3027 [#:local-build? #f] [#:substitutable? #t] [#:guile-for-build #f]
3028 Return a derivation that executes Scheme expression @var{exp} as a
3029 builder for derivation @var{name}. @var{inputs} must be a list of
3030 @code{(name drv-path sub-drv)} tuples; when @var{sub-drv} is omitted,
3031 @code{"out"} is assumed. @var{modules} is a list of names of Guile
3032 modules from the current search path to be copied in the store,
3033 compiled, and made available in the load path during the execution of
3034 @var{exp}---e.g., @code{((guix build utils) (guix build
3035 gnu-build-system))}.
3037 @var{exp} is evaluated in an environment where @code{%outputs} is bound
3038 to a list of output/path pairs, and where @code{%build-inputs} is bound
3039 to a list of string/output-path pairs made from @var{inputs}.
3040 Optionally, @var{env-vars} is a list of string pairs specifying the name
3041 and value of environment variables visible to the builder. The builder
3042 terminates by passing the result of @var{exp} to @code{exit}; thus, when
3043 @var{exp} returns @code{#f}, the build is considered to have failed.
3045 @var{exp} is built using @var{guile-for-build} (a derivation). When
3046 @var{guile-for-build} is omitted or is @code{#f}, the value of the
3047 @code{%guile-for-build} fluid is used instead.
3049 See the @code{derivation} procedure for the meaning of
3050 @var{references-graphs}, @var{allowed-references}, @var{local-build?},
3051 and @var{substitutable?}.
3055 Here's an example of a single-output derivation that creates a directory
3056 containing one file:
3059 (let ((builder '(let ((out (assoc-ref %outputs "out")))
3060 (mkdir out) ; create /gnu/store/@dots{}-goo
3061 (call-with-output-file (string-append out "/test")
3063 (display '(hello guix) p))))))
3064 (build-expression->derivation store "goo" builder))
3066 @result{} #<derivation /gnu/store/@dots{}-goo.drv => @dots{}>
3070 @node The Store Monad
3071 @section The Store Monad
3075 The procedures that operate on the store described in the previous
3076 sections all take an open connection to the build daemon as their first
3077 argument. Although the underlying model is functional, they either have
3078 side effects or depend on the current state of the store.
3080 The former is inconvenient: the connection to the build daemon has to be
3081 carried around in all those functions, making it impossible to compose
3082 functions that do not take that parameter with functions that do. The
3083 latter can be problematic: since store operations have side effects
3084 and/or depend on external state, they have to be properly sequenced.
3086 @cindex monadic values
3087 @cindex monadic functions
3088 This is where the @code{(guix monads)} module comes in. This module
3089 provides a framework for working with @dfn{monads}, and a particularly
3090 useful monad for our uses, the @dfn{store monad}. Monads are a
3091 construct that allows two things: associating ``context'' with values
3092 (in our case, the context is the store), and building sequences of
3093 computations (here computations include accesses to the store.) Values
3094 in a monad---values that carry this additional context---are called
3095 @dfn{monadic values}; procedures that return such values are called
3096 @dfn{monadic procedures}.
3098 Consider this ``normal'' procedure:
3101 (define (sh-symlink store)
3102 ;; Return a derivation that symlinks the 'bash' executable.
3103 (let* ((drv (package-derivation store bash))
3104 (out (derivation->output-path drv))
3105 (sh (string-append out "/bin/bash")))
3106 (build-expression->derivation store "sh"
3107 `(symlink ,sh %output))))
3110 Using @code{(guix monads)} and @code{(guix gexp)}, it may be rewritten
3111 as a monadic function:
3114 (define (sh-symlink)
3115 ;; Same, but return a monadic value.
3116 (mlet %store-monad ((drv (package->derivation bash)))
3117 (gexp->derivation "sh"
3118 #~(symlink (string-append #$drv "/bin/bash")
3122 There several things to note in the second version: the @code{store}
3123 parameter is now implicit and is ``threaded'' in the calls to the
3124 @code{package->derivation} and @code{gexp->derivation} monadic
3125 procedures, and the monadic value returned by @code{package->derivation}
3126 is @dfn{bound} using @code{mlet} instead of plain @code{let}.
3128 As it turns out, the call to @code{package->derivation} can even be
3129 omitted since it will take place implicitly, as we will see later
3130 (@pxref{G-Expressions}):
3133 (define (sh-symlink)
3134 (gexp->derivation "sh"
3135 #~(symlink (string-append #$bash "/bin/bash")
3140 @c <https://syntaxexclamation.wordpress.com/2014/06/26/escaping-continuations/>
3141 @c for the funny quote.
3142 Calling the monadic @code{sh-symlink} has no effect. As someone once
3143 said, ``you exit a monad like you exit a building on fire: by running''.
3144 So, to exit the monad and get the desired effect, one must use
3145 @code{run-with-store}:
3148 (run-with-store (open-connection) (sh-symlink))
3149 @result{} /gnu/store/...-sh-symlink
3152 Note that the @code{(guix monad-repl)} module extends Guile's REPL with
3153 new ``meta-commands'' to make it easier to deal with monadic procedures:
3154 @code{run-in-store}, and @code{enter-store-monad}. The former, is used
3155 to ``run'' a single monadic value through the store:
3158 scheme@@(guile-user)> ,run-in-store (package->derivation hello)
3159 $1 = #<derivation /gnu/store/@dots{}-hello-2.9.drv => @dots{}>
3162 The latter enters a recursive REPL, where all the return values are
3163 automatically run through the store:
3166 scheme@@(guile-user)> ,enter-store-monad
3167 store-monad@@(guile-user) [1]> (package->derivation hello)
3168 $2 = #<derivation /gnu/store/@dots{}-hello-2.9.drv => @dots{}>
3169 store-monad@@(guile-user) [1]> (text-file "foo" "Hello!")
3170 $3 = "/gnu/store/@dots{}-foo"
3171 store-monad@@(guile-user) [1]> ,q
3172 scheme@@(guile-user)>
3176 Note that non-monadic values cannot be returned in the
3177 @code{store-monad} REPL.
3179 The main syntactic forms to deal with monads in general are provided by
3180 the @code{(guix monads)} module and are described below.
3182 @deffn {Scheme Syntax} with-monad @var{monad} @var{body} ...
3183 Evaluate any @code{>>=} or @code{return} forms in @var{body} as being
3187 @deffn {Scheme Syntax} return @var{val}
3188 Return a monadic value that encapsulates @var{val}.
3191 @deffn {Scheme Syntax} >>= @var{mval} @var{mproc} ...
3192 @dfn{Bind} monadic value @var{mval}, passing its ``contents'' to monadic
3193 procedures @var{mproc}@dots{}@footnote{This operation is commonly
3194 referred to as ``bind'', but that name denotes an unrelated procedure in
3195 Guile. Thus we use this somewhat cryptic symbol inherited from the
3196 Haskell language.}. There can be one @var{mproc} or several of them, as
3201 (with-monad %state-monad
3203 (lambda (x) (return (+ 1 x)))
3204 (lambda (x) (return (* 2 x)))))
3208 @result{} some-state
3212 @deffn {Scheme Syntax} mlet @var{monad} ((@var{var} @var{mval}) ...) @
3214 @deffnx {Scheme Syntax} mlet* @var{monad} ((@var{var} @var{mval}) ...) @
3216 Bind the variables @var{var} to the monadic values @var{mval} in
3217 @var{body}. The form (@var{var} -> @var{val}) binds @var{var} to the
3218 ``normal'' value @var{val}, as per @code{let}.
3220 @code{mlet*} is to @code{mlet} what @code{let*} is to @code{let}
3221 (@pxref{Local Bindings,,, guile, GNU Guile Reference Manual}).
3224 @deffn {Scheme System} mbegin @var{monad} @var{mexp} ...
3225 Bind @var{mexp} and the following monadic expressions in sequence,
3226 returning the result of the last expression.
3228 This is akin to @code{mlet}, except that the return values of the
3229 monadic expressions are ignored. In that sense, it is analogous to
3230 @code{begin}, but applied to monadic expressions.
3234 The @code{(guix monads)} module provides the @dfn{state monad}, which
3235 allows an additional value---the state---to be @emph{threaded} through
3236 monadic procedure calls.
3238 @defvr {Scheme Variable} %state-monad
3239 The state monad. Procedures in the state monad can access and change
3240 the state that is threaded.
3242 Consider the example below. The @code{square} procedure returns a value
3243 in the state monad. It returns the square of its argument, but also
3244 increments the current state value:
3248 (mlet %state-monad ((count (current-state)))
3249 (mbegin %state-monad
3250 (set-current-state (+ 1 count))
3253 (run-with-state (sequence %state-monad (map square (iota 3))) 0)
3258 When ``run'' through @var{%state-monad}, we obtain that additional state
3259 value, which is the number of @code{square} calls.
3262 @deffn {Monadic Procedure} current-state
3263 Return the current state as a monadic value.
3266 @deffn {Monadic Procedure} set-current-state @var{value}
3267 Set the current state to @var{value} and return the previous state as a
3271 @deffn {Monadic Procedure} state-push @var{value}
3272 Push @var{value} to the current state, which is assumed to be a list,
3273 and return the previous state as a monadic value.
3276 @deffn {Monadic Procedure} state-pop
3277 Pop a value from the current state and return it as a monadic value.
3278 The state is assumed to be a list.
3281 @deffn {Scheme Procedure} run-with-state @var{mval} [@var{state}]
3282 Run monadic value @var{mval} starting with @var{state} as the initial
3283 state. Return two values: the resulting value, and the resulting state.
3286 The main interface to the store monad, provided by the @code{(guix
3287 store)} module, is as follows.
3289 @defvr {Scheme Variable} %store-monad
3290 The store monad---an alias for @var{%state-monad}.
3292 Values in the store monad encapsulate accesses to the store. When its
3293 effect is needed, a value of the store monad must be ``evaluated'' by
3294 passing it to the @code{run-with-store} procedure (see below.)
3297 @deffn {Scheme Procedure} run-with-store @var{store} @var{mval} [#:guile-for-build] [#:system (%current-system)]
3298 Run @var{mval}, a monadic value in the store monad, in @var{store}, an
3299 open store connection.
3302 @deffn {Monadic Procedure} text-file @var{name} @var{text} [@var{references}]
3303 Return as a monadic value the absolute file name in the store of the file
3304 containing @var{text}, a string. @var{references} is a list of store items that the
3305 resulting text file refers to; it defaults to the empty list.
3308 @deffn {Monadic Procedure} interned-file @var{file} [@var{name}] @
3310 Return the name of @var{file} once interned in the store. Use
3311 @var{name} as its store name, or the basename of @var{file} if
3312 @var{name} is omitted.
3314 When @var{recursive?} is true, the contents of @var{file} are added
3315 recursively; if @var{file} designates a flat file and @var{recursive?}
3316 is true, its contents are added, and its permission bits are kept.
3318 The example below adds a file to the store, under two different names:
3321 (run-with-store (open-connection)
3322 (mlet %store-monad ((a (interned-file "README"))
3323 (b (interned-file "README" "LEGU-MIN")))
3324 (return (list a b))))
3326 @result{} ("/gnu/store/rwm@dots{}-README" "/gnu/store/44i@dots{}-LEGU-MIN")
3331 The @code{(guix packages)} module exports the following package-related
3334 @deffn {Monadic Procedure} package-file @var{package} [@var{file}] @
3335 [#:system (%current-system)] [#:target #f] @
3336 [#:output "out"] Return as a monadic
3337 value in the absolute file name of @var{file} within the @var{output}
3338 directory of @var{package}. When @var{file} is omitted, return the name
3339 of the @var{output} directory of @var{package}. When @var{target} is
3340 true, use it as a cross-compilation target triplet.
3343 @deffn {Monadic Procedure} package->derivation @var{package} [@var{system}]
3344 @deffnx {Monadic Procedure} package->cross-derivation @var{package} @
3345 @var{target} [@var{system}]
3346 Monadic version of @code{package-derivation} and
3347 @code{package-cross-derivation} (@pxref{Defining Packages}).
3352 @section G-Expressions
3354 @cindex G-expression
3355 @cindex build code quoting
3356 So we have ``derivations'', which represent a sequence of build actions
3357 to be performed to produce an item in the store (@pxref{Derivations}).
3358 Those build actions are performed when asking the daemon to actually
3359 build the derivations; they are run by the daemon in a container
3360 (@pxref{Invoking guix-daemon}).
3362 @cindex strata of code
3363 It should come as no surprise that we like to write those build actions
3364 in Scheme. When we do that, we end up with two @dfn{strata} of Scheme
3365 code@footnote{The term @dfn{stratum} in this context was coined by
3366 Manuel Serrano et al.@: in the context of their work on Hop. Oleg
3367 Kiselyov, who has written insightful
3368 @url{http://okmij.org/ftp/meta-programming/#meta-scheme, essays and code
3369 on this topic}, refers to this kind of code generation as
3370 @dfn{staging}.}: the ``host code''---code that defines packages, talks
3371 to the daemon, etc.---and the ``build code''---code that actually
3372 performs build actions, such as making directories, invoking
3373 @command{make}, etc.
3375 To describe a derivation and its build actions, one typically needs to
3376 embed build code inside host code. It boils down to manipulating build
3377 code as data, and Scheme's homoiconicity---code has a direct
3378 representation as data---comes in handy for that. But we need more than
3379 Scheme's normal @code{quasiquote} mechanism to construct build
3382 The @code{(guix gexp)} module implements @dfn{G-expressions}, a form of
3383 S-expressions adapted to build expressions. G-expressions, or
3384 @dfn{gexps}, consist essentially in three syntactic forms: @code{gexp},
3385 @code{ungexp}, and @code{ungexp-splicing} (or simply: @code{#~},
3386 @code{#$}, and @code{#$@@}), which are comparable respectively to
3387 @code{quasiquote}, @code{unquote}, and @code{unquote-splicing}
3388 (@pxref{Expression Syntax, @code{quasiquote},, guile, GNU Guile
3389 Reference Manual}). However, there are major differences:
3393 Gexps are meant to be written to a file and run or manipulated by other
3397 When a high-level object such as a package or derivation is unquoted
3398 inside a gexp, the result is as if its output file name had been
3402 Gexps carry information about the packages or derivations they refer to,
3403 and these dependencies are automatically added as inputs to the build
3404 processes that use them.
3407 @cindex lowering, of high-level objects in gexps
3408 This mechanism is not limited to package and derivation
3409 objects: @dfn{compilers} able to ``lower'' other high-level objects to
3410 derivations or files in the store can be defined,
3411 such that these objects can also be inserted
3412 into gexps. For example, a useful type of high-level object that can be
3413 inserted in a gexp is ``file-like objects'', which make it easy to
3414 add files to the store and refer to them in
3415 derivations and such (see @code{local-file} and @code{plain-file}
3418 To illustrate the idea, here is an example of a gexp:
3425 (symlink (string-append #$coreutils "/bin/ls")
3429 This gexp can be passed to @code{gexp->derivation}; we obtain a
3430 derivation that builds a directory containing exactly one symlink to
3431 @file{/gnu/store/@dots{}-coreutils-8.22/bin/ls}:
3434 (gexp->derivation "the-thing" build-exp)
3437 As one would expect, the @code{"/gnu/store/@dots{}-coreutils-8.22"} string is
3438 substituted to the reference to the @var{coreutils} package in the
3439 actual build code, and @var{coreutils} is automatically made an input to
3440 the derivation. Likewise, @code{#$output} (equivalent to @code{(ungexp
3441 output)}) is replaced by a string containing the derivation's output
3444 @cindex cross compilation
3445 In a cross-compilation context, it is useful to distinguish between
3446 references to the @emph{native} build of a package---that can run on the
3447 host---versus references to cross builds of a package. To that end, the
3448 @code{#+} plays the same role as @code{#$}, but is a reference to a
3449 native package build:
3452 (gexp->derivation "vi"
3455 (system* (string-append #+coreutils "/bin/ln")
3457 (string-append #$emacs "/bin/emacs")
3458 (string-append #$output "/bin/vi")))
3459 #:target "mips64el-linux")
3463 In the example above, the native build of @var{coreutils} is used, so
3464 that @command{ln} can actually run on the host; but then the
3465 cross-compiled build of @var{emacs} is referenced.
3467 The syntactic form to construct gexps is summarized below.
3469 @deffn {Scheme Syntax} #~@var{exp}
3470 @deffnx {Scheme Syntax} (gexp @var{exp})
3471 Return a G-expression containing @var{exp}. @var{exp} may contain one
3472 or more of the following forms:
3476 @itemx (ungexp @var{obj})
3477 Introduce a reference to @var{obj}. @var{obj} may have one of the
3478 supported types, for example a package or a
3479 derivation, in which case the @code{ungexp} form is replaced by its
3480 output file name---e.g., @code{"/gnu/store/@dots{}-coreutils-8.22}.
3482 If @var{obj} is a list, it is traversed and references to supported
3483 objects are substituted similarly.
3485 If @var{obj} is another gexp, its contents are inserted and its
3486 dependencies are added to those of the containing gexp.
3488 If @var{obj} is another kind of object, it is inserted as is.
3490 @item #$@var{obj}:@var{output}
3491 @itemx (ungexp @var{obj} @var{output})
3492 This is like the form above, but referring explicitly to the
3493 @var{output} of @var{obj}---this is useful when @var{obj} produces
3494 multiple outputs (@pxref{Packages with Multiple Outputs}).
3497 @itemx #+@var{obj}:output
3498 @itemx (ungexp-native @var{obj})
3499 @itemx (ungexp-native @var{obj} @var{output})
3500 Same as @code{ungexp}, but produces a reference to the @emph{native}
3501 build of @var{obj} when used in a cross compilation context.
3503 @item #$output[:@var{output}]
3504 @itemx (ungexp output [@var{output}])
3505 Insert a reference to derivation output @var{output}, or to the main
3506 output when @var{output} is omitted.
3508 This only makes sense for gexps passed to @code{gexp->derivation}.
3511 @itemx (ungexp-splicing @var{lst})
3512 Like the above, but splices the contents of @var{lst} inside the
3516 @itemx (ungexp-native-splicing @var{lst})
3517 Like the above, but refers to native builds of the objects listed in
3522 G-expressions created by @code{gexp} or @code{#~} are run-time objects
3523 of the @code{gexp?} type (see below.)
3526 @deffn {Scheme Procedure} gexp? @var{obj}
3527 Return @code{#t} if @var{obj} is a G-expression.
3530 G-expressions are meant to be written to disk, either as code building
3531 some derivation, or as plain files in the store. The monadic procedures
3532 below allow you to do that (@pxref{The Store Monad}, for more
3533 information about monads.)
3535 @deffn {Monadic Procedure} gexp->derivation @var{name} @var{exp} @
3536 [#:system (%current-system)] [#:target #f] [#:graft? #t] @
3537 [#:hash #f] [#:hash-algo #f] @
3538 [#:recursive? #f] [#:env-vars '()] [#:modules '()] @
3539 [#:module-path @var{%load-path}] @
3540 [#:references-graphs #f] [#:allowed-references #f] @
3541 [#:leaked-env-vars #f] @
3542 [#:script-name (string-append @var{name} "-builder")] @
3543 [#:local-build? #f] [#:substitutable? #t] [#:guile-for-build #f]
3544 Return a derivation @var{name} that runs @var{exp} (a gexp) with
3545 @var{guile-for-build} (a derivation) on @var{system}; @var{exp} is
3546 stored in a file called @var{script-name}. When @var{target} is true,
3547 it is used as the cross-compilation target triplet for packages referred
3550 Make @var{modules} available in the evaluation context of @var{exp};
3551 @var{modules} is a list of names of Guile modules searched in
3552 @var{module-path} to be copied in the store, compiled, and made available in
3553 the load path during the execution of @var{exp}---e.g., @code{((guix
3554 build utils) (guix build gnu-build-system))}.
3556 @var{graft?} determines whether packages referred to by @var{exp} should be grafted when
3559 When @var{references-graphs} is true, it must be a list of tuples of one of the
3563 (@var{file-name} @var{package})
3564 (@var{file-name} @var{package} @var{output})
3565 (@var{file-name} @var{derivation})
3566 (@var{file-name} @var{derivation} @var{output})
3567 (@var{file-name} @var{store-item})
3570 The right-hand-side of each element of @var{references-graphs} is automatically made
3571 an input of the build process of @var{exp}. In the build environment, each
3572 @var{file-name} contains the reference graph of the corresponding item, in a simple
3575 @var{allowed-references} must be either @code{#f} or a list of output names and packages.
3576 In the latter case, the list denotes store items that the result is allowed to
3577 refer to. Any reference to another store item will lead to a build error.
3579 The other arguments are as for @code{derivation} (@pxref{Derivations}).
3582 @cindex file-like objects
3583 The @code{local-file}, @code{plain-file}, @code{computed-file},
3584 @code{program-file}, and @code{scheme-file} procedures below return
3585 @dfn{file-like objects}. That is, when unquoted in a G-expression,
3586 these objects lead to a file in the store. Consider this G-expression:
3589 #~(system* (string-append #$glibc "/sbin/nscd") "-f"
3590 #$(local-file "/tmp/my-nscd.conf"))
3593 The effect here is to ``intern'' @file{/tmp/my-nscd.conf} by copying it
3594 to the store. Once expanded, for instance @i{via}
3595 @code{gexp->derivation}, the G-expression refers to that copy under
3596 @file{/gnu/store}; thus, modifying or removing the file in @file{/tmp}
3597 does not have any effect on what the G-expression does.
3598 @code{plain-file} can be used similarly; it differs in that the file
3599 content is directly passed as a string.
3601 @deffn {Scheme Procedure} local-file @var{file} [@var{name}] @
3603 Return an object representing local file @var{file} to add to the store; this
3604 object can be used in a gexp. If @var{file} is a relative file name, it is looked
3605 up relative to the source file where this form appears. @var{file} will be added to
3606 the store under @var{name}--by default the base name of @var{file}.
3608 When @var{recursive?} is true, the contents of @var{file} are added recursively; if @var{file}
3609 designates a flat file and @var{recursive?} is true, its contents are added, and its
3610 permission bits are kept.
3612 This is the declarative counterpart of the @code{interned-file} monadic
3613 procedure (@pxref{The Store Monad, @code{interned-file}}).
3616 @deffn {Scheme Procedure} plain-file @var{name} @var{content}
3617 Return an object representing a text file called @var{name} with the given
3618 @var{content} (a string) to be added to the store.
3620 This is the declarative counterpart of @code{text-file}.
3623 @deffn {Scheme Procedure} computed-file @var{name} @var{gexp} @
3624 [#:modules '()] [#:options '(#:local-build? #t)]
3625 Return an object representing the store item @var{name}, a file or
3626 directory computed by @var{gexp}. @var{modules} specifies the set of
3627 modules visible in the execution context of @var{gexp}. @var{options}
3628 is a list of additional arguments to pass to @code{gexp->derivation}.
3630 This is the declarative counterpart of @code{gexp->derivation}.
3633 @deffn {Monadic Procedure} gexp->script @var{name} @var{exp}
3634 Return an executable script @var{name} that runs @var{exp} using
3635 @var{guile} with @var{modules} in its search path.
3637 The example below builds a script that simply invokes the @command{ls}
3641 (use-modules (guix gexp) (gnu packages base))
3643 (gexp->script "list-files"
3644 #~(execl (string-append #$coreutils "/bin/ls")
3648 When ``running'' it through the store (@pxref{The Store Monad,
3649 @code{run-with-store}}), we obtain a derivation that produces an
3650 executable file @file{/gnu/store/@dots{}-list-files} along these lines:
3653 #!/gnu/store/@dots{}-guile-2.0.11/bin/guile -ds
3655 (execl (string-append "/gnu/store/@dots{}-coreutils-8.22"/bin/ls")
3660 @deffn {Scheme Procedure} program-file @var{name} @var{exp} @
3661 [#:modules '()] [#:guile #f]
3662 Return an object representing the executable store item @var{name} that
3663 runs @var{gexp}. @var{guile} is the Guile package used to execute that
3664 script, and @var{modules} is the list of modules visible to that script.
3666 This is the declarative counterpart of @code{gexp->script}.
3669 @deffn {Monadic Procedure} gexp->file @var{name} @var{exp}
3670 Return a derivation that builds a file @var{name} containing @var{exp}.
3672 The resulting file holds references to all the dependencies of @var{exp}
3673 or a subset thereof.
3676 @deffn {Scheme Procedure} scheme-file @var{name} @var{exp}
3677 Return an object representing the Scheme file @var{name} that contains
3680 This is the declarative counterpart of @code{gexp->file}.
3683 @deffn {Monadic Procedure} text-file* @var{name} @var{text} @dots{}
3684 Return as a monadic value a derivation that builds a text file
3685 containing all of @var{text}. @var{text} may list, in addition to
3686 strings, objects of any type that can be used in a gexp: packages,
3687 derivations, local file objects, etc. The resulting store file holds
3688 references to all these.
3690 This variant should be preferred over @code{text-file} anytime the file
3691 to create will reference items from the store. This is typically the
3692 case when building a configuration file that embeds store file names,
3696 (define (profile.sh)
3697 ;; Return the name of a shell script in the store that
3698 ;; initializes the 'PATH' environment variable.
3699 (text-file* "profile.sh"
3700 "export PATH=" coreutils "/bin:"
3701 grep "/bin:" sed "/bin\n"))
3704 In this example, the resulting @file{/gnu/store/@dots{}-profile.sh} file
3705 will references @var{coreutils}, @var{grep}, and @var{sed}, thereby
3706 preventing them from being garbage-collected during its lifetime.
3709 @deffn {Scheme Procedure} mixed-text-file @var{name} @var{text} @dots{}
3710 Return an object representing store file @var{name} containing
3711 @var{text}. @var{text} is a sequence of strings and file-like objects,
3715 (mixed-text-file "profile"
3716 "export PATH=" coreutils "/bin:" grep "/bin")
3719 This is the declarative counterpart of @code{text-file*}.
3722 Of course, in addition to gexps embedded in ``host'' code, there are
3723 also modules containing build tools. To make it clear that they are
3724 meant to be used in the build stratum, these modules are kept in the
3725 @code{(guix build @dots{})} name space.
3727 @cindex lowering, of high-level objects in gexps
3728 Internally, high-level objects are @dfn{lowered}, using their compiler,
3729 to either derivations or store items. For instance, lowering a package
3730 yields a derivation, and lowering a @code{plain-file} yields a store
3731 item. This is achieved using the @code{lower-object} monadic procedure.
3733 @deffn {Monadic Procedure} lower-object @var{obj} [@var{system}] @
3735 Return as a value in @var{%store-monad} the derivation or store item
3736 corresponding to @var{obj} for @var{system}, cross-compiling for
3737 @var{target} if @var{target} is true. @var{obj} must be an object that
3738 has an associated gexp compiler, such as a @code{<package>}.
3742 @c *********************************************************************
3746 This section describes tools primarily targeted at developers and users
3747 who write new package definitions. They complement the Scheme
3748 programming interface of Guix in a convenient way.
3751 * Invoking guix build:: Building packages from the command line.
3752 * Invoking guix edit:: Editing package definitions.
3753 * Invoking guix download:: Downloading a file and printing its hash.
3754 * Invoking guix hash:: Computing the cryptographic hash of a file.
3755 * Invoking guix import:: Importing package definitions.
3756 * Invoking guix refresh:: Updating package definitions.
3757 * Invoking guix lint:: Finding errors in package definitions.
3758 * Invoking guix size:: Profiling disk usage.
3759 * Invoking guix graph:: Visualizing the graph of packages.
3760 * Invoking guix environment:: Setting up development environments.
3761 * Invoking guix publish:: Sharing substitutes.
3762 * Invoking guix challenge:: Challenging substitute servers.
3763 * Invoking guix container:: Process isolation.
3766 @node Invoking guix build
3767 @section Invoking @command{guix build}
3769 The @command{guix build} command builds packages or derivations and
3770 their dependencies, and prints the resulting store paths. Note that it
3771 does not modify the user's profile---this is the job of the
3772 @command{guix package} command (@pxref{Invoking guix package}). Thus,
3773 it is mainly useful for distribution developers.
3775 The general syntax is:
3778 guix build @var{options} @var{package-or-derivation}@dots{}
3781 As an example, the following command builds the latest version of Emacs
3782 and of Guile, displays their build logs, and finally displays the
3783 resulting directories:
3786 guix build emacs guile
3789 Similarly, the following command builds all the available packages:
3792 guix build --keep-going \
3793 `guix package -A | cut -f1,2 --output-delimiter=@@`
3796 @var{package-or-derivation} may be either the name of a package found in
3797 the software distribution such as @code{coreutils} or
3798 @code{coreutils-8.20}, or a derivation such as
3799 @file{/gnu/store/@dots{}-coreutils-8.19.drv}. In the former case, a
3800 package with the corresponding name (and optionally version) is searched
3801 for among the GNU distribution modules (@pxref{Package Modules}).
3803 Alternatively, the @code{--expression} option may be used to specify a
3804 Scheme expression that evaluates to a package; this is useful when
3805 disambiguation among several same-named packages or package variants is
3808 There may be zero or more @var{options}. The available options are
3809 described in the subsections below.
3812 * Common Build Options:: Build options for most commands.
3813 * Additional Build Options:: Options specific to 'guix build'.
3816 @node Common Build Options
3817 @subsection Common Build Options
3819 A number of options that control the build process are common to
3820 @command{guix build} and other commands that can spawn builds, such as
3821 @command{guix package} or @command{guix archive}. These are the
3826 @item --load-path=@var{directory}
3827 @itemx -L @var{directory}
3828 Add @var{directory} to the front of the package module search path
3829 (@pxref{Package Modules}).
3831 This allows users to define their own packages and make them visible to
3832 the command-line tools.
3836 Keep the build tree of failed builds. Thus, if a build fail, its build
3837 tree is kept under @file{/tmp}, in a directory whose name is shown at
3838 the end of the build log. This is useful when debugging build issues.
3842 Keep going when some of the derivations fail to build; return only once
3843 all the builds have either completed or failed.
3845 The default behavior is to stop as soon as one of the specified
3846 derivations has failed.
3850 Do not build the derivations.
3853 When substituting a pre-built binary fails, fall back to building
3856 @item --substitute-urls=@var{urls}
3857 @anchor{client-substitute-urls}
3858 Consider @var{urls} the whitespace-separated list of substitute source
3859 URLs, overriding the default list of URLs of @command{guix-daemon}
3860 (@pxref{daemon-substitute-urls,, @command{guix-daemon} URLs}).
3862 This means that substitutes may be downloaded from @var{urls}, provided
3863 they are signed by a key authorized by the system administrator
3864 (@pxref{Substitutes}).
3866 @item --no-substitutes
3867 Do not use substitutes for build products. That is, always build things
3868 locally instead of allowing downloads of pre-built binaries
3869 (@pxref{Substitutes}).
3871 @item --rounds=@var{n}
3872 Build each derivation @var{n} times in a row, and raise an error if
3873 consecutive build results are not bit-for-bit identical.
3875 This is a useful way to detect non-deterministic builds processes.
3876 Non-deterministic build processes are a problem because they make it
3877 practically impossible for users to @emph{verify} whether third-party
3878 binaries are genuine. @xref{Invoking guix challenge}, for more.
3880 Note that, currently, the differing build results are not kept around,
3881 so you will have to manually investigate in case of an error---e.g., by
3882 stashing one of the build results with @code{guix archive --export},
3883 then rebuilding, and finally comparing the two results.
3885 @item --no-build-hook
3886 Do not attempt to offload builds @i{via} the daemon's ``build hook''
3887 (@pxref{Daemon Offload Setup}). That is, always build things locally
3888 instead of offloading builds to remote machines.
3890 @item --max-silent-time=@var{seconds}
3891 When the build or substitution process remains silent for more than
3892 @var{seconds}, terminate it and report a build failure.
3894 @item --timeout=@var{seconds}
3895 Likewise, when the build or substitution process lasts for more than
3896 @var{seconds}, terminate it and report a build failure.
3898 By default there is no timeout. This behavior can be restored with
3901 @item --verbosity=@var{level}
3902 Use the given verbosity level. @var{level} must be an integer between 0
3903 and 5; higher means more verbose output. Setting a level of 4 or more
3904 may be helpful when debugging setup issues with the build daemon.
3906 @item --cores=@var{n}
3908 Allow the use of up to @var{n} CPU cores for the build. The special
3909 value @code{0} means to use as many CPU cores as available.
3911 @item --max-jobs=@var{n}
3913 Allow at most @var{n} build jobs in parallel. @xref{Invoking
3914 guix-daemon, @code{--max-jobs}}, for details about this option and the
3915 equivalent @command{guix-daemon} option.
3919 Behind the scenes, @command{guix build} is essentially an interface to
3920 the @code{package-derivation} procedure of the @code{(guix packages)}
3921 module, and to the @code{build-derivations} procedure of the @code{(guix
3922 derivations)} module.
3924 In addition to options explicitly passed on the command line,
3925 @command{guix build} and other @command{guix} commands that support
3926 building honor the @code{GUIX_BUILD_OPTIONS} environment variable.
3928 @defvr {Environment Variable} GUIX_BUILD_OPTIONS
3929 Users can define this variable to a list of command line options that
3930 will automatically be used by @command{guix build} and other
3931 @command{guix} commands that can perform builds, as in the example
3935 $ export GUIX_BUILD_OPTIONS="--no-substitutes -c 2 -L /foo/bar"
3938 These options are parsed independently, and the result is appended to
3939 the parsed command-line options.
3942 @node Additional Build Options
3943 @subsection Additional Build Options
3945 The command-line options presented below are specific to @command{guix
3950 @item --file=@var{file}
3951 @itemx -f @var{file}
3953 Build the package or derivation that the code within @var{file}
3956 As an example, @var{file} might contain a package definition like this
3957 (@pxref{Defining Packages}):
3960 @verbatiminclude package-hello.scm
3963 @item --expression=@var{expr}
3964 @itemx -e @var{expr}
3965 Build the package or derivation @var{expr} evaluates to.
3967 For example, @var{expr} may be @code{(@@ (gnu packages guile)
3968 guile-1.8)}, which unambiguously designates this specific variant of
3969 version 1.8 of Guile.
3971 Alternately, @var{expr} may be a G-expression, in which case it is used
3972 as a build program passed to @code{gexp->derivation}
3973 (@pxref{G-Expressions}).
3975 Lastly, @var{expr} may refer to a zero-argument monadic procedure
3976 (@pxref{The Store Monad}). The procedure must return a derivation as a
3977 monadic value, which is then passed through @code{run-with-store}.
3981 Build the packages' source derivations, rather than the packages
3984 For instance, @code{guix build -S gcc} returns something like
3985 @file{/gnu/store/@dots{}-gcc-4.7.2.tar.bz2}, which is GCC's source tarball.
3987 The returned source tarball is the result of applying any patches and
3988 code snippets specified in the package's @code{origin} (@pxref{Defining
3992 Fetch and return the source of @var{package-or-derivation} and all their
3993 dependencies, recursively. This is a handy way to obtain a local copy
3994 of all the source code needed to build @var{packages}, allowing you to
3995 eventually build them even without network access. It is an extension
3996 of the @code{--source} option and can accept one of the following
3997 optional argument values:
4001 This value causes the @code{--sources} option to behave in the same way
4002 as the @code{--source} option.
4005 Build all packages' source derivations, including any source that might
4006 be listed as @code{inputs}. This is the default value.
4009 $ guix build --sources tzdata
4010 The following derivations will be built:
4011 /gnu/store/@dots{}-tzdata2015b.tar.gz.drv
4012 /gnu/store/@dots{}-tzcode2015b.tar.gz.drv
4016 Build all packages' source derivations, as well as all source
4017 derivations for packages' transitive inputs. This can be used e.g. to
4018 prefetch package source for later offline building.
4021 $ guix build --sources=transitive tzdata
4022 The following derivations will be built:
4023 /gnu/store/@dots{}-tzcode2015b.tar.gz.drv
4024 /gnu/store/@dots{}-findutils-4.4.2.tar.xz.drv
4025 /gnu/store/@dots{}-grep-2.21.tar.xz.drv
4026 /gnu/store/@dots{}-coreutils-8.23.tar.xz.drv
4027 /gnu/store/@dots{}-make-4.1.tar.xz.drv
4028 /gnu/store/@dots{}-bash-4.3.tar.xz.drv
4034 @item --system=@var{system}
4035 @itemx -s @var{system}
4036 Attempt to build for @var{system}---e.g., @code{i686-linux}---instead of
4037 the host's system type.
4039 An example use of this is on Linux-based systems, which can emulate
4040 different personalities. For instance, passing
4041 @code{--system=i686-linux} on an @code{x86_64-linux} system allows users
4042 to build packages in a complete 32-bit environment.
4044 @item --target=@var{triplet}
4045 @cindex cross-compilation
4046 Cross-build for @var{triplet}, which must be a valid GNU triplet, such
4047 as @code{"mips64el-linux-gnu"} (@pxref{Configuration Names, GNU
4048 configuration triplets,, configure, GNU Configure and Build System}).
4050 @item --with-source=@var{source}
4051 Use @var{source} as the source of the corresponding package.
4052 @var{source} must be a file name or a URL, as for @command{guix
4053 download} (@pxref{Invoking guix download}).
4055 The ``corresponding package'' is taken to be one specified on the
4056 command line whose name matches the base of @var{source}---e.g., if
4057 @var{source} is @code{/src/guile-2.0.10.tar.gz}, the corresponding
4058 package is @code{guile}. Likewise, the version string is inferred from
4059 @var{source}; in the previous example, it's @code{2.0.10}.
4061 This option allows users to try out versions of packages other than the
4062 one provided by the distribution. The example below downloads
4063 @file{ed-1.7.tar.gz} from a GNU mirror and uses that as the source for
4064 the @code{ed} package:
4067 guix build ed --with-source=mirror://gnu/ed/ed-1.7.tar.gz
4070 As a developer, @code{--with-source} makes it easy to test release
4074 guix build guile --with-source=../guile-2.0.9.219-e1bb7.tar.xz
4077 @dots{} or to build from a checkout in a pristine environment:
4080 $ git clone git://git.sv.gnu.org/guix.git
4081 $ guix build guix --with-source=./guix
4084 @anchor{build-check}
4086 @cindex determinism, checking
4087 @cindex reproducibility, checking
4088 Rebuild @var{package-or-derivation}, which are already available in the
4089 store, and raise an error if the build results are not bit-for-bit
4092 This mechanism allows you to check whether previously-installed
4093 substitutes are genuine (@pxref{Substitutes}), or whether a package's
4094 build result is deterministic. @xref{Invoking guix challenge}, for more
4095 background information and tools.
4098 Do not ``graft'' packages. In practice, this means that package updates
4099 available as grafts are not applied. @xref{Security Updates}, for more
4100 information on grafts.
4104 Return the derivation paths, not the output paths, of the given
4107 @item --root=@var{file}
4108 @itemx -r @var{file}
4109 Make @var{file} a symlink to the result, and register it as a garbage
4113 Return the build log file names or URLs for the given
4114 @var{package-or-derivation}s, or raise an error if build logs are
4117 This works regardless of how packages or derivations are specified. For
4118 instance, the following invocations are equivalent:
4121 guix build --log-file `guix build -d guile`
4122 guix build --log-file `guix build guile`
4123 guix build --log-file guile
4124 guix build --log-file -e '(@@ (gnu packages guile) guile-2.0)'
4127 If a log is unavailable locally, and unless @code{--no-substitutes} is
4128 passed, the command looks for a corresponding log on one of the
4129 substitute servers (as specified with @code{--substitute-urls}.)
4131 So for instance, let's say you want to see the build log of GDB on MIPS
4132 but you're actually on an @code{x86_64} machine:
4135 $ guix build --log-file gdb -s mips64el-linux
4136 http://hydra.gnu.org/log/@dots{}-gdb-7.10
4139 You can freely access a huge library of build logs!
4143 @node Invoking guix edit
4144 @section Invoking @command{guix edit}
4146 @cindex package definition, editing
4147 So many packages, so many source files! The @command{guix edit} command
4148 facilitates the life of packagers by pointing their editor at the source
4149 file containing the definition of the specified packages. For instance:
4152 guix edit gcc-4.8 vim
4156 launches the program specified in the @code{VISUAL} or in the
4157 @code{EDITOR} environment variable to edit the recipe of GCC@tie{}4.8.4
4160 If you are using Emacs, note that the Emacs user interface provides
4161 similar functionality in the ``package info'' and ``package list''
4162 buffers created by @kbd{M-x guix-search-by-name} and similar commands
4163 (@pxref{Emacs Commands}).
4166 @node Invoking guix download
4167 @section Invoking @command{guix download}
4169 When writing a package definition, developers typically need to download
4170 the package's source tarball, compute its SHA256 hash, and write that
4171 hash in the package definition (@pxref{Defining Packages}). The
4172 @command{guix download} tool helps with this task: it downloads a file
4173 from the given URI, adds it to the store, and prints both its file name
4174 in the store and its SHA256 hash.
4176 The fact that the downloaded file is added to the store saves bandwidth:
4177 when the developer eventually tries to build the newly defined package
4178 with @command{guix build}, the source tarball will not have to be
4179 downloaded again because it is already in the store. It is also a
4180 convenient way to temporarily stash files, which may be deleted
4181 eventually (@pxref{Invoking guix gc}).
4183 The @command{guix download} command supports the same URIs as used in
4184 package definitions. In particular, it supports @code{mirror://} URIs.
4185 @code{https} URIs (HTTP over TLS) are supported @emph{provided} the
4186 Guile bindings for GnuTLS are available in the user's environment; when
4187 they are not available, an error is raised. @xref{Guile Preparations,
4188 how to install the GnuTLS bindings for Guile,, gnutls-guile,
4189 GnuTLS-Guile}, for more information.
4191 The following option is available:
4194 @item --format=@var{fmt}
4196 Write the hash in the format specified by @var{fmt}. For more
4197 information on the valid values for @var{fmt}, @pxref{Invoking guix hash}.
4200 @node Invoking guix hash
4201 @section Invoking @command{guix hash}
4203 The @command{guix hash} command computes the SHA256 hash of a file.
4204 It is primarily a convenience tool for anyone contributing to the
4205 distribution: it computes the cryptographic hash of a file, which can be
4206 used in the definition of a package (@pxref{Defining Packages}).
4208 The general syntax is:
4211 guix hash @var{option} @var{file}
4214 @command{guix hash} has the following option:
4218 @item --format=@var{fmt}
4220 Write the hash in the format specified by @var{fmt}.
4222 Supported formats: @code{nix-base32}, @code{base32}, @code{base16}
4223 (@code{hex} and @code{hexadecimal} can be used as well).
4225 If the @option{--format} option is not specified, @command{guix hash}
4226 will output the hash in @code{nix-base32}. This representation is used
4227 in the definitions of packages.
4231 Compute the hash on @var{file} recursively.
4233 In this case, the hash is computed on an archive containing @var{file},
4234 including its children if it is a directory. Some of @var{file}'s
4235 meta-data is part of the archive; for instance, when @var{file} is a
4236 regular file, the hash is different depending on whether @var{file} is
4237 executable or not. Meta-data such as time stamps has no impact on the
4238 hash (@pxref{Invoking guix archive}).
4239 @c FIXME: Replace xref above with xref to an ``Archive'' section when
4244 @node Invoking guix import
4245 @section Invoking @command{guix import}
4247 @cindex importing packages
4248 @cindex package import
4249 @cindex package conversion
4250 The @command{guix import} command is useful for people willing to add a
4251 package to the distribution but who'd rather do as little work as
4252 possible to get there---a legitimate demand. The command knows of a few
4253 repositories from which it can ``import'' package meta-data. The result
4254 is a package definition, or a template thereof, in the format we know
4255 (@pxref{Defining Packages}).
4257 The general syntax is:
4260 guix import @var{importer} @var{options}@dots{}
4263 @var{importer} specifies the source from which to import package
4264 meta-data, and @var{options} specifies a package identifier and other
4265 options specific to @var{importer}. Currently, the available
4270 Import meta-data for the given GNU package. This provides a template
4271 for the latest version of that GNU package, including the hash of its
4272 source tarball, and its canonical synopsis and description.
4274 Additional information such as the package's dependencies and its
4275 license needs to be figured out manually.
4277 For example, the following command returns a package definition for
4281 guix import gnu hello
4284 Specific command-line options are:
4287 @item --key-download=@var{policy}
4288 As for @code{guix refresh}, specify the policy to handle missing OpenPGP
4289 keys when verifying the package's signature. @xref{Invoking guix
4290 refresh, @code{--key-download}}.
4295 Import meta-data from the @uref{https://pypi.python.org/, Python Package
4296 Index}@footnote{This functionality requires Guile-JSON to be installed.
4297 @xref{Requirements}.}. Information is taken from the JSON-formatted
4298 description available at @code{pypi.python.org} and usually includes all
4299 the relevant information, including package dependencies.
4301 The command below imports meta-data for the @code{itsdangerous} Python
4305 guix import pypi itsdangerous
4310 Import meta-data from @uref{https://rubygems.org/,
4311 RubyGems}@footnote{This functionality requires Guile-JSON to be
4312 installed. @xref{Requirements}.}. Information is taken from the
4313 JSON-formatted description available at @code{rubygems.org} and includes
4314 most relevant information, including runtime dependencies. There are
4315 some caveats, however. The meta-data doesn't distinguish between
4316 synopses and descriptions, so the same string is used for both fields.
4317 Additionally, the details of non-Ruby dependencies required to build
4318 native extensions is unavailable and left as an exercise to the
4321 The command below imports meta-data for the @code{rails} Ruby package:
4324 guix import gem rails
4329 Import meta-data from @uref{https://www.metacpan.org/, MetaCPAN}.
4330 Information is taken from the JSON-formatted meta-data provided through
4331 @uref{https://api.metacpan.org/, MetaCPAN's API} and includes most
4332 relevant information, such as module dependencies. License information
4333 should be checked closely. If Perl is available in the store, then the
4334 @code{corelist} utility will be used to filter core modules out of the
4335 list of dependencies.
4337 The command command below imports meta-data for the @code{Acme::Boolean}
4341 guix import cpan Acme::Boolean
4346 @cindex Bioconductor
4347 Import meta-data from @uref{http://cran.r-project.org/, CRAN}, the
4348 central repository for the @uref{http://r-project.org, GNU@tie{}R
4349 statistical and graphical environment}.
4351 Information is extracted from the package's @code{DESCRIPTION} file.
4353 The command command below imports meta-data for the @code{Cairo}
4357 guix import cran Cairo
4360 When @code{--archive=bioconductor} is added, meta-data is imported from
4361 @uref{http://www.bioconductor.org/, Bioconductor}, a repository of R
4362 packages for for the analysis and comprehension of high-throughput
4363 genomic data in bioinformatics.
4365 Information is extracted from a package's @code{DESCRIPTION} file
4366 published on the web interface of the Bioconductor SVN repository.
4368 The command command below imports meta-data for the @code{GenomicRanges}
4372 guix import cran --archive=bioconductor GenomicRanges
4376 Import meta-data from a local copy of the source of the
4377 @uref{http://nixos.org/nixpkgs/, Nixpkgs distribution}@footnote{This
4378 relies on the @command{nix-instantiate} command of
4379 @uref{http://nixos.org/nix/, Nix}.}. Package definitions in Nixpkgs are
4380 typically written in a mixture of Nix-language and Bash code. This
4381 command only imports the high-level package structure that is written in
4382 the Nix language. It normally includes all the basic fields of a
4385 When importing a GNU package, the synopsis and descriptions are replaced
4386 by their canonical upstream variant.
4388 Usually, you will first need to do:
4391 export NIX_REMOTE=daemon
4395 so that @command{nix-instantiate} does not try to open the Nix database.
4397 As an example, the command below imports the package definition of
4398 LibreOffice (more precisely, it imports the definition of the package
4399 bound to the @code{libreoffice} top-level attribute):
4402 guix import nix ~/path/to/nixpkgs libreoffice
4407 Import meta-data from Haskell community's central package archive
4408 @uref{https://hackage.haskell.org/, Hackage}. Information is taken from
4409 Cabal files and includes all the relevant information, including package
4412 Specific command-line options are:
4417 Read a Cabal file from the standard input.
4418 @item --no-test-dependencies
4420 Do not include dependencies required by the test suites only.
4421 @item --cabal-environment=@var{alist}
4422 @itemx -e @var{alist}
4423 @var{alist} is a Scheme alist defining the environment in which the
4424 Cabal conditionals are evaluated. The accepted keys are: @code{os},
4425 @code{arch}, @code{impl} and a string representing the name of a flag.
4426 The value associated with a flag has to be either the symbol
4427 @code{true} or @code{false}. The value associated with other keys
4428 has to conform to the Cabal file format definition. The default value
4429 associated with the keys @code{os}, @code{arch} and @code{impl} is
4430 @samp{linux}, @samp{x86_64} and @samp{ghc} respectively.
4433 The command below imports meta-data for the latest version of the
4434 @code{HTTP} Haskell package without including test dependencies and
4435 specifying the value of the flag @samp{network-uri} as @code{false}:
4438 guix import hackage -t -e "'((\"network-uri\" . false))" HTTP
4441 A specific package version may optionally be specified by following the
4442 package name by a hyphen and a version number as in the following example:
4445 guix import hackage mtl-2.1.3.1
4450 Import meta-data from an Emacs Lisp Package Archive (ELPA) package
4451 repository (@pxref{Packages,,, emacs, The GNU Emacs Manual}).
4453 Specific command-line options are:
4456 @item --archive=@var{repo}
4457 @itemx -a @var{repo}
4458 @var{repo} identifies the archive repository from which to retrieve the
4459 information. Currently the supported repositories and their identifiers
4463 @uref{http://elpa.gnu.org/packages, GNU}, selected by the @code{gnu}
4464 identifier. This is the default.
4467 @uref{http://stable.melpa.org/packages, MELPA-Stable}, selected by the
4468 @code{melpa-stable} identifier.
4471 @uref{http://melpa.org/packages, MELPA}, selected by the @code{melpa}
4477 The structure of the @command{guix import} code is modular. It would be
4478 useful to have more importers for other package formats, and your help
4479 is welcome here (@pxref{Contributing}).
4481 @node Invoking guix refresh
4482 @section Invoking @command{guix refresh}
4484 The primary audience of the @command{guix refresh} command is developers
4485 of the GNU software distribution. By default, it reports any packages
4486 provided by the distribution that are outdated compared to the latest
4487 upstream version, like this:
4491 gnu/packages/gettext.scm:29:13: gettext would be upgraded from 0.18.1.1 to 0.18.2.1
4492 gnu/packages/glib.scm:77:12: glib would be upgraded from 2.34.3 to 2.37.0
4495 It does so by browsing each package's FTP directory and determining the
4496 highest version number of the source tarballs therein. The command
4497 knows how to update specific types of packages: GNU packages, ELPA
4498 packages, etc.---see the documentation for @option{--type} below. The
4499 are many packages, though, for which it lacks a method to determine
4500 whether a new upstream release is available. However, the mechanism is
4501 extensible, so feel free to get in touch with us to add a new method!
4503 When passed @code{--update}, it modifies distribution source files to
4504 update the version numbers and source tarball hashes of those packages'
4505 recipes (@pxref{Defining Packages}). This is achieved by downloading
4506 each package's latest source tarball and its associated OpenPGP
4507 signature, authenticating the downloaded tarball against its signature
4508 using @command{gpg}, and finally computing its hash. When the public
4509 key used to sign the tarball is missing from the user's keyring, an
4510 attempt is made to automatically retrieve it from a public key server;
4511 when it's successful, the key is added to the user's keyring; otherwise,
4512 @command{guix refresh} reports an error.
4514 The following options are supported:
4518 @item --expression=@var{expr}
4519 @itemx -e @var{expr}
4520 Consider the package @var{expr} evaluates to.
4522 This is useful to precisely refer to a package, as in this example:
4525 guix refresh -l -e '(@@@@ (gnu packages commencement) glibc-final)'
4528 This command lists the dependents of the ``final'' libc (essentially all
4533 Update distribution source files (package recipes) in place. This is
4534 usually run from a checkout of the Guix source tree (@pxref{Running
4535 Guix Before It Is Installed}):
4538 $ ./pre-inst-env guix refresh -s non-core
4541 @xref{Defining Packages}, for more information on package definitions.
4543 @item --select=[@var{subset}]
4544 @itemx -s @var{subset}
4545 Select all the packages in @var{subset}, one of @code{core} or
4548 The @code{core} subset refers to all the packages at the core of the
4549 distribution---i.e., packages that are used to build ``everything
4550 else''. This includes GCC, libc, Binutils, Bash, etc. Usually,
4551 changing one of these packages in the distribution entails a rebuild of
4552 all the others. Thus, such updates are an inconvenience to users in
4553 terms of build time or bandwidth used to achieve the upgrade.
4555 The @code{non-core} subset refers to the remaining packages. It is
4556 typically useful in cases where an update of the core packages would be
4559 @item --type=@var{updater}
4560 @itemx -t @var{updater}
4561 Select only packages handled by @var{updater} (may be a comma-separated
4562 list of updaters). Currently, @var{updater} may be one of:
4566 the updater for GNU packages;
4568 the updater for GNOME packages;
4570 the updater for @uref{http://elpa.gnu.org/, ELPA} packages;
4572 the updater for @uref{http://cran.r-project.org/, CRAN} packages;
4574 the updater for @uref{http://www.bioconductor.org/, Bioconductor} R packages;
4576 the updater for @uref{https://pypi.python.org, PyPI} packages.
4579 For instance, the following commands only checks for updates of Emacs
4580 packages hosted at @code{elpa.gnu.org} and updates of CRAN packages:
4583 $ guix refresh --type=elpa,cran
4584 gnu/packages/statistics.scm:819:13: r-testthat would be upgraded from 0.10.0 to 0.11.0
4585 gnu/packages/emacs.scm:856:13: emacs-auctex would be upgraded from 11.88.6 to 11.88.9
4590 In addition, @command{guix refresh} can be passed one or more package
4591 names, as in this example:
4594 $ ./pre-inst-env guix refresh -u emacs idutils gcc-4.8.4
4598 The command above specifically updates the @code{emacs} and
4599 @code{idutils} packages. The @code{--select} option would have no
4600 effect in this case.
4602 When considering whether to upgrade a package, it is sometimes
4603 convenient to know which packages would be affected by the upgrade and
4604 should be checked for compatibility. For this the following option may
4605 be used when passing @command{guix refresh} one or more package names:
4609 @item --list-updaters
4611 List available updaters and exit (see @option{--type} above.)
4613 @item --list-dependent
4615 List top-level dependent packages that would need to be rebuilt as a
4616 result of upgrading one or more packages.
4620 Be aware that the @code{--list-dependent} option only
4621 @emph{approximates} the rebuilds that would be required as a result of
4622 an upgrade. More rebuilds might be required under some circumstances.
4625 $ guix refresh --list-dependent flex
4626 Building the following 120 packages would ensure 213 dependent packages are rebuilt:
4627 hop-2.4.0 geiser-0.4 notmuch-0.18 mu-0.9.9.5 cflow-1.4 idutils-4.6 @dots{}
4630 The command above lists a set of packages that could be built to check
4631 for compatibility with an upgraded @code{flex} package.
4633 The following options can be used to customize GnuPG operation:
4637 @item --gpg=@var{command}
4638 Use @var{command} as the GnuPG 2.x command. @var{command} is searched
4639 for in @code{$PATH}.
4641 @item --key-download=@var{policy}
4642 Handle missing OpenPGP keys according to @var{policy}, which may be one
4647 Always download missing OpenPGP keys from the key server, and add them
4648 to the user's GnuPG keyring.
4651 Never try to download missing OpenPGP keys. Instead just bail out.
4654 When a package signed with an unknown OpenPGP key is encountered, ask
4655 the user whether to download it or not. This is the default behavior.
4658 @item --key-server=@var{host}
4659 Use @var{host} as the OpenPGP key server when importing a public key.
4663 @node Invoking guix lint
4664 @section Invoking @command{guix lint}
4665 The @command{guix lint} is meant to help package developers avoid common
4666 errors and use a consistent style. It runs a number of checks on a
4667 given set of packages in order to find common mistakes in their
4668 definitions. Available @dfn{checkers} include (see
4669 @code{--list-checkers} for a complete list):
4674 Validate certain typographical and stylistic rules about package
4675 descriptions and synopses.
4677 @item inputs-should-be-native
4678 Identify inputs that should most likely be native inputs.
4682 @itemx source-file-name
4683 Probe @code{home-page} and @code{source} URLs and report those that are
4684 invalid. Check that the source file name is meaningful, e.g. is not
4685 just a version number or ``git-checkout'', and should not have a
4686 @code{file-name} declared (@pxref{origin Reference}).
4689 Report known vulnerabilities found in the Common Vulnerabilities and
4690 Exposures (CVE) database
4691 @uref{https://nvd.nist.gov/download.cfm#CVE_FEED, published by the US
4695 Warn about obvious source code formatting issues: trailing white space,
4696 use of tabulations, etc.
4699 The general syntax is:
4702 guix lint @var{options} @var{package}@dots{}
4705 If no package is given on the command line, then all packages are checked.
4706 The @var{options} may be zero or more of the following:
4712 Only enable the checkers specified in a comma-separated list using the
4713 names returned by @code{--list-checkers}.
4715 @item --list-checkers
4717 List and describe all the available checkers that will be run on packages
4722 @node Invoking guix size
4723 @section Invoking @command{guix size}
4725 The @command{guix size} command helps package developers profile the
4726 disk usage of packages. It is easy to overlook the impact of an
4727 additional dependency added to a package, or the impact of using a
4728 single output for a package that could easily be split (@pxref{Packages
4729 with Multiple Outputs}). These are the typical issues that
4730 @command{guix size} can highlight.
4732 The command can be passed a package specification such as @code{gcc-4.8}
4733 or @code{guile:debug}, or a file name in the store. Consider this
4737 $ guix size coreutils
4738 store item total self
4739 /gnu/store/@dots{}-coreutils-8.23 70.0 13.9 19.8%
4740 /gnu/store/@dots{}-gmp-6.0.0a 55.3 2.5 3.6%
4741 /gnu/store/@dots{}-acl-2.2.52 53.7 0.5 0.7%
4742 /gnu/store/@dots{}-attr-2.4.46 53.2 0.3 0.5%
4743 /gnu/store/@dots{}-gcc-4.8.4-lib 52.9 15.7 22.4%
4744 /gnu/store/@dots{}-glibc-2.21 37.2 37.2 53.1%
4748 The store items listed here constitute the @dfn{transitive closure} of
4749 Coreutils---i.e., Coreutils and all its dependencies, recursively---as
4750 would be returned by:
4753 $ guix gc -R /gnu/store/@dots{}-coreutils-8.23
4756 Here the output shows 3 columns next to store items. The first column,
4757 labeled ``total'', shows the size in mebibytes (MiB) of the closure of
4758 the store item---that is, its own size plus the size of all its
4759 dependencies. The next column, labeled ``self'', shows the size of the
4760 item itself. The last column shows the ratio of the item's size to the
4761 space occupied by all the items listed here.
4763 In this example, we see that the closure of Coreutils weighs in at
4764 70@tie{}MiB, half of which is taken by libc. (That libc represents a
4765 large fraction of the closure is not a problem @i{per se} because it is
4766 always available on the system anyway.)
4768 When the package passed to @command{guix size} is available in the
4769 store, @command{guix size} queries the daemon to determine its
4770 dependencies, and measures its size in the store, similar to @command{du
4771 -ms --apparent-size} (@pxref{du invocation,,, coreutils, GNU
4774 When the given package is @emph{not} in the store, @command{guix size}
4775 reports information based on information about the available substitutes
4776 (@pxref{Substitutes}). This allows it to profile disk usage of store
4777 items that are not even on disk, only available remotely.
4779 The available options are:
4783 @item --substitute-urls=@var{urls}
4784 Use substitute information from @var{urls}.
4785 @xref{client-substitute-urls, the same option for @code{guix build}}.
4787 @item --map-file=@var{file}
4788 Write to @var{file} a graphical map of disk usage as a PNG file.
4790 For the example above, the map looks like this:
4792 @image{images/coreutils-size-map,5in,, map of Coreutils disk usage
4793 produced by @command{guix size}}
4795 This option requires that
4796 @uref{http://wingolog.org/software/guile-charting/, Guile-Charting} be
4797 installed and visible in Guile's module search path. When that is not
4798 the case, @command{guix size} fails as it tries to load it.
4800 @item --system=@var{system}
4801 @itemx -s @var{system}
4802 Consider packages for @var{system}---e.g., @code{x86_64-linux}.
4806 @node Invoking guix graph
4807 @section Invoking @command{guix graph}
4810 Packages and their dependencies form a @dfn{graph}, specifically a
4811 directed acyclic graph (DAG). It can quickly become difficult to have a
4812 mental model of the package DAG, so the @command{guix graph} command is
4813 here to provide a visual representation of the DAG. @command{guix
4814 graph} emits a DAG representation in the input format of
4815 @uref{http://www.graphviz.org/, Graphviz}, so its output can be passed
4816 directly to Graphviz's @command{dot} command, for instance. The general
4820 guix graph @var{options} @var{package}@dots{}
4823 For example, the following command generates a PDF file representing the
4824 package DAG for the GNU@tie{}Core Utilities, showing its build-time
4828 guix graph coreutils | dot -Tpdf > dag.pdf
4831 The output looks like this:
4833 @image{images/coreutils-graph,2in,,Dependency graph of the GNU Coreutils}
4835 Nice little graph, no?
4837 But there's more than one graph! The one above is concise: it's the
4838 graph of package objects, omitting implicit inputs such as GCC, libc,
4839 grep, etc. It's often useful to have such a concise graph, but
4840 sometimes you want to see more details. @command{guix graph} supports
4841 several types of graphs, allowing you to choose the level of details:
4845 This is the default type, the one we used above. It shows the DAG of
4846 package objects, excluding implicit dependencies. It is concise, but
4847 filters out many details.
4850 This is the package DAG, @emph{including} implicit inputs.
4852 For instance, the following command:
4855 guix graph --type=bag-emerged coreutils | dot -Tpdf > dag.pdf
4858 ... yields this bigger graph:
4860 @image{images/coreutils-bag-graph,,5in,Detailed dependency graph of the GNU Coreutils}
4862 At the bottom of the graph, we see all the implicit inputs of
4863 @var{gnu-build-system} (@pxref{Build Systems, @code{gnu-build-system}}).
4865 Now, note that the dependencies of those implicit inputs---that is, the
4866 @dfn{bootstrap dependencies} (@pxref{Bootstrapping})---are not shown
4867 here, for conciseness.
4870 Similar to @code{bag-emerged}, but this time including all the bootstrap
4873 @item bag-with-origins
4874 Similar to @code{bag}, but also showing origins and their dependencies.
4877 This is the most detailed representation: It shows the DAG of
4878 derivations (@pxref{Derivations}) and plain store items. Compared to
4879 the above representation, many additional nodes are visible, including
4880 builds scripts, patches, Guile modules, etc.
4884 All the above types correspond to @emph{build-time dependencies}. The
4885 following graph type represents the @emph{run-time dependencies}:
4889 This is the graph of @dfn{references} of a package output, as returned
4890 by @command{guix gc --references} (@pxref{Invoking guix gc}).
4892 If the given package output is not available in the store, @command{guix
4893 graph} attempts to obtain dependency information from substitutes.
4896 The available options are the following:
4899 @item --type=@var{type}
4900 @itemx -t @var{type}
4901 Produce a graph output of @var{type}, where @var{type} must be one of
4902 the values listed above.
4905 List the supported graph types.
4907 @item --expression=@var{expr}
4908 @itemx -e @var{expr}
4909 Consider the package @var{expr} evaluates to.
4911 This is useful to precisely refer to a package, as in this example:
4914 guix graph -e '(@@@@ (gnu packages commencement) gnu-make-final)'
4919 @node Invoking guix environment
4920 @section Invoking @command{guix environment}
4922 @cindex reproducible build environments
4923 @cindex development environments
4924 The purpose of @command{guix environment} is to assist hackers in
4925 creating reproducible development environments without polluting their
4926 package profile. The @command{guix environment} tool takes one or more
4927 packages, builds all of the necessary inputs, and creates a shell
4928 environment to use them.
4930 The general syntax is:
4933 guix environment @var{options} @var{package}@dots{}
4936 The following example spawns a new shell set up for the development of
4940 guix environment guile
4943 If the specified packages are not built yet, @command{guix environment}
4944 automatically builds them. The new shell's environment is an augmented
4945 version of the environment that @command{guix environment} was run in.
4946 It contains the necessary search paths for building the given package
4947 added to the existing environment variables. To create a ``pure''
4948 environment in which the original environment variables have been unset,
4949 use the @code{--pure} option@footnote{Users sometimes wrongfully augment
4950 environment variables such as @code{PATH} in their @file{~/.bashrc}
4951 file. As a consequence, when @code{guix environment} launches it, Bash
4952 may read @file{~/.bashrc}, thereby introducing ``impurities'' in these
4953 environment variables. It is an error to define such environment
4954 variables in @file{.bashrc}; instead, they should be defined in
4955 @file{.bash_profile}, which is sourced only by log-in shells.
4956 @xref{Bash Startup Files,,, bash, The GNU Bash Reference Manual}, for
4957 details on Bash start-up files.}.
4959 @vindex GUIX_ENVIRONMENT
4960 @command{guix environment} defines the @code{GUIX_ENVIRONMENT}
4961 variable in the shell it spaws. This allows users to, say, define a
4962 specific prompt for development environments in their @file{.bashrc}
4963 (@pxref{Bash Startup Files,,, bash, The GNU Bash Reference Manual}):
4966 if [ -n "$GUIX_ENVIRONMENT" ]
4968 export PS1="\u@@\h \w [dev]\$ "
4972 Additionally, more than one package may be specified, in which case the
4973 union of the inputs for the given packages are used. For example, the
4974 command below spawns a shell where all of the dependencies of both Guile
4975 and Emacs are available:
4978 guix environment guile emacs
4981 Sometimes an interactive shell session is not desired. An arbitrary
4982 command may be invoked by placing the @code{--} token to separate the
4983 command from the rest of the arguments:
4986 guix environment guile -- make -j4
4989 In other situations, it is more convenient to specify the list of
4990 packages needed in the environment. For example, the following command
4991 runs @command{python} from an environment containing Python@tie{}2.7 and
4995 guix environment --ad-hoc python2-numpy python-2.7 -- python
4998 Furthermore, one might want the dependencies of a package and also some
4999 additional packages that are not build-time or runtime dependencies, but
5000 are useful when developing nonetheless. Because of this, the
5001 @code{--ad-hoc} flag is positional. Packages appearing before
5002 @code{--ad-hoc} are interpreted as packages whose dependencies will be
5003 added to the environment. Packages appearing after are interpreted as
5004 packages that will be added to the environment directly. For example,
5005 the following command creates a Guix development environment that
5006 additionally includes Git and strace:
5009 guix environment guix --ad-hoc git strace
5012 Sometimes it is desirable to isolate the environment as much as
5013 possible, for maximal purity and reproducibility. In particular, when
5014 using Guix on a host distro that is not GuixSD, it is desirable to
5015 prevent access to @file{/usr/bin} and other system-wide resources from
5016 the development environment. For example, the following command spawns
5017 a Guile REPL in a ``container'' where only the store and the current
5018 working directory are mounted:
5021 guix environment --ad-hoc --container guile -- guile
5025 The @code{--container} option requires Linux-libre 3.19 or newer.
5028 The available options are summarized below.
5031 @item --expression=@var{expr}
5032 @itemx -e @var{expr}
5033 Create an environment for the package or list of packages that
5034 @var{expr} evaluates to.
5036 For example, running:
5039 guix environment -e '(@@ (gnu packages maths) petsc-openmpi)'
5042 starts a shell with the environment for this specific variant of the
5048 guix environment --ad-hoc -e '(@@ (gnu) %base-packages)'
5051 starts a shell with all the GuixSD base packages available.
5053 @item --load=@var{file}
5054 @itemx -l @var{file}
5055 Create an environment for the package or list of packages that the code
5056 within @var{file} evaluates to.
5058 As an example, @var{file} might contain a definition like this
5059 (@pxref{Defining Packages}):
5062 @verbatiminclude environment-gdb.scm
5066 Include all specified packages in the resulting environment, as if an
5067 @i{ad hoc} package were defined with them as inputs. This option is
5068 useful for quickly creating an environment without having to write a
5069 package expression to contain the desired inputs.
5071 For instance, the command:
5074 guix environment --ad-hoc guile guile-sdl -- guile
5077 runs @command{guile} in an environment where Guile and Guile-SDL are
5080 Note that this example implicitly asks for the default output of
5081 @code{guile} and @code{guile-sdl} but it is possible to ask for a
5082 specific output---e.g., @code{glib:bin} asks for the @code{bin} output
5083 of @code{glib} (@pxref{Packages with Multiple Outputs}).
5085 This option may be composed with the default behavior of @command{guix
5086 environment}. Packages appearing before @code{--ad-hoc} are interpreted
5087 as packages whose dependencies will be added to the environment, the
5088 default behavior. Packages appearing after are interpreted as packages
5089 that will be added to the environment directly.
5092 Unset existing environment variables when building the new environment.
5093 This has the effect of creating an environment in which search paths
5094 only contain package inputs.
5096 @item --search-paths
5097 Display the environment variable definitions that make up the
5100 @item --system=@var{system}
5101 @itemx -s @var{system}
5102 Attempt to build for @var{system}---e.g., @code{i686-linux}.
5107 Run @var{command} within an isolated container. The current working
5108 directory outside the container is mapped inside the
5109 container. Additionally, the spawned process runs as the current user
5110 outside the container, but has root privileges in the context of the
5115 For containers, share the network namespace with the host system.
5116 Containers created without this flag only have access to the loopback
5119 @item --expose=@var{source}[=@var{target}]
5120 For containers, expose the file system @var{source} from the host system
5121 as the read-only file system @var{target} within the container. If
5122 @var{target} is not specified, @var{source} is used as the target mount
5123 point in the container.
5125 The example below spawns a Guile REPL in a container in which the user's
5126 home directory is accessible read-only via the @file{/exchange}
5130 guix environment --container --expose=$HOME=/exchange guile -- guile
5133 @item --share=@var{source}[=@var{target}]
5134 For containers, share the file system @var{source} from the host system
5135 as the writable file system @var{target} within the container. If
5136 @var{target} is not specified, @var{source} is used as the target mount
5137 point in the container.
5139 The example below spawns a Guile REPL in a container in which the user's
5140 home directory is accessible for both reading and writing via the
5141 @file{/exchange} directory:
5144 guix environment --container --share=$HOME=/exchange guile -- guile
5148 It also supports all of the common build options that @command{guix
5149 build} supports (@pxref{Common Build Options}).
5151 @node Invoking guix publish
5152 @section Invoking @command{guix publish}
5154 The purpose of @command{guix publish} is to enable users to easily share
5155 their store with others, which can then use it as a substitute server
5156 (@pxref{Substitutes}).
5158 When @command{guix publish} runs, it spawns an HTTP server which allows
5159 anyone with network access to obtain substitutes from it. This means
5160 that any machine running Guix can also act as if it were a build farm,
5161 since the HTTP interface is compatible with Hydra, the software behind
5162 the @code{hydra.gnu.org} build farm.
5164 For security, each substitute is signed, allowing recipients to check
5165 their authenticity and integrity (@pxref{Substitutes}). Because
5166 @command{guix publish} uses the system's signing key, which is only
5167 readable by the system administrator, it must be started as root; the
5168 @code{--user} option makes it drop root privileges early on.
5170 The signing key pair must be generated before @command{guix publish} is
5171 launched, using @command{guix archive --generate-key} (@pxref{Invoking
5174 The general syntax is:
5177 guix publish @var{options}@dots{}
5180 Running @command{guix publish} without any additional arguments will
5181 spawn an HTTP server on port 8080:
5187 Once a publishing server has been authorized (@pxref{Invoking guix
5188 archive}), the daemon may download substitutes from it:
5191 guix-daemon --substitute-urls=http://example.org:8080
5194 The following options are available:
5197 @item --port=@var{port}
5198 @itemx -p @var{port}
5199 Listen for HTTP requests on @var{port}.
5201 @item --listen=@var{host}
5202 Listen on the network interface for @var{host}. The default is to
5203 accept connections from any interface.
5205 @item --user=@var{user}
5206 @itemx -u @var{user}
5207 Change privileges to @var{user} as soon as possible---i.e., once the
5208 server socket is open and the signing key has been read.
5210 @item --repl[=@var{port}]
5211 @itemx -r [@var{port}]
5212 Spawn a Guile REPL server (@pxref{REPL Servers,,, guile, GNU Guile
5213 Reference Manual}) on @var{port} (37146 by default). This is used
5214 primarily for debugging a running @command{guix publish} server.
5217 Enabling @command{guix publish} on a GuixSD system is a one-liner: just
5218 add a call to @code{guix-publish-service} in the @code{services} field
5219 of the @code{operating-system} declaration (@pxref{guix-publish-service,
5220 @code{guix-publish-service}}).
5223 @node Invoking guix challenge
5224 @section Invoking @command{guix challenge}
5226 @cindex reproducible builds
5227 @cindex verifiable builds
5229 Do the binaries provided by this server really correspond to the source
5230 code it claims to build? Is this package's build process deterministic?
5231 These are the questions the @command{guix challenge} command attempts to
5234 The former is obviously an important question: Before using a substitute
5235 server (@pxref{Substitutes}), you'd rather @emph{verify} that it
5236 provides the right binaries, and thus @emph{challenge} it. The latter
5237 is what enables the former: If package builds are deterministic, then
5238 independent builds of the package should yield the exact same result,
5239 bit for bit; if a server provides a binary different from the one
5240 obtained locally, it may be either corrupt or malicious.
5242 We know that the hash that shows up in @file{/gnu/store} file names is
5243 the hash of all the inputs of the process that built the file or
5244 directory---compilers, libraries, build scripts,
5245 etc. (@pxref{Introduction}). Assuming deterministic build processes,
5246 one store file name should map to exactly one build output.
5247 @command{guix challenge} checks whether there is, indeed, a single
5248 mapping by comparing the build outputs of several independent builds of
5249 any given store item.
5251 The command's output looks like this:
5254 $ guix challenge --substitute-urls="http://hydra.gnu.org http://guix.example.org"
5255 updating list of substitutes from 'http://hydra.gnu.org'... 100.0%
5256 updating list of substitutes from 'http://guix.example.org'... 100.0%
5257 /gnu/store/@dots{}-openssl-1.0.2d contents differ:
5258 local hash: 0725l22r5jnzazaacncwsvp9kgf42266ayyp814v7djxs7nk963q
5259 http://hydra.gnu.org/nar/@dots{}-openssl-1.0.2d: 0725l22r5jnzazaacncwsvp9kgf42266ayyp814v7djxs7nk963q
5260 http://guix.example.org/nar/@dots{}-openssl-1.0.2d: 1zy4fmaaqcnjrzzajkdn3f5gmjk754b43qkq47llbyak9z0qjyim
5261 /gnu/store/@dots{}-git-2.5.0 contents differ:
5262 local hash: 00p3bmryhjxrhpn2gxs2fy0a15lnip05l97205pgbk5ra395hyha
5263 http://hydra.gnu.org/nar/@dots{}-git-2.5.0: 069nb85bv4d4a6slrwjdy8v1cn4cwspm3kdbmyb81d6zckj3nq9f
5264 http://guix.example.org/nar/@dots{}-git-2.5.0: 0mdqa9w1p6cmli6976v4wi0sw9r4p5prkj7lzfd1877wk11c9c73
5265 /gnu/store/@dots{}-pius-2.1.1 contents differ:
5266 local hash: 0k4v3m9z1zp8xzzizb7d8kjj72f9172xv078sq4wl73vnq9ig3ax
5267 http://hydra.gnu.org/nar/@dots{}-pius-2.1.1: 0k4v3m9z1zp8xzzizb7d8kjj72f9172xv078sq4wl73vnq9ig3ax
5268 http://guix.example.org/nar/@dots{}-pius-2.1.1: 1cy25x1a4fzq5rk0pmvc8xhwyffnqz95h2bpvqsz2mpvlbccy0gs
5272 In this example, @command{guix challenge} first scans the store to
5273 determine the set of locally-built derivations---as opposed to store
5274 items that were downloaded from a substitute server---and then queries
5275 all the substitute servers. It then reports those store items for which
5276 the servers obtained a result different from the local build.
5278 @cindex non-determinism, in package builds
5279 As an example, @code{guix.example.org} always gets a different answer.
5280 Conversely, @code{hydra.gnu.org} agrees with local builds, except in the
5281 case of Git. This might indicate that the build process of Git is
5282 non-deterministic, meaning that its output varies as a function of
5283 various things that Guix does not fully control, in spite of building
5284 packages in isolated environments (@pxref{Features}). Most common
5285 sources of non-determinism include the addition of timestamps in build
5286 results, the inclusion of random numbers, and directory listings sorted
5287 by inode number. See @uref{http://reproducible.debian.net/howto/}, for
5290 To find out what's wrong with this Git binary, we can do something along
5291 these lines (@pxref{Invoking guix archive}):
5294 $ wget -q -O - http://hydra.gnu.org/nar/@dots{}-git-2.5.0 \
5295 | guix archive -x /tmp/git
5296 $ diff -ur --no-dereference /gnu/store/@dots{}-git.2.5.0 /tmp/git
5299 This command shows the difference between the files resulting from the
5300 local build, and the files resulting from the build on
5301 @code{hydra.gnu.org} (@pxref{Overview, Comparing and Merging Files,,
5302 diffutils, Comparing and Merging Files}). The @command{diff} command
5303 works great for text files. When binary files differ, a better option
5304 is @uref{http://diffoscope.org/, Diffoscope}, a tool that helps
5305 visualize differences for all kinds of files.
5307 Once you've done that work, you can tell whether the differences are due
5308 to a non-deterministic build process or to a malicious server. We try
5309 hard to remove sources of non-determinism in packages to make it easier
5310 to verify substitutes, but of course, this is a process, one that
5311 involves not just Guix but a large part of the free software community.
5312 In the meantime, @command{guix challenge} is one tool to help address
5315 If you are writing packages for Guix, you are encouraged to check
5316 whether @code{hydra.gnu.org} and other substitute servers obtain the
5317 same build result as you did with:
5320 $ guix challenge @var{package}
5324 ... where @var{package} is a package specification such as
5325 @code{guile-2.0} or @code{glibc:debug}.
5327 The general syntax is:
5330 guix challenge @var{options} [@var{packages}@dots{}]
5333 The one option that matters is:
5337 @item --substitute-urls=@var{urls}
5338 Consider @var{urls} the whitespace-separated list of substitute source
5344 @node Invoking guix container
5345 @section Invoking @command{guix container}
5349 As of version @value{VERSION}, this tool is experimental. The interface
5350 is subject to radical change in the future.
5353 The purpose of @command{guix container} is to manipulate processes
5354 running within an isolated environment, commonly known as a
5355 ``container'', typically created by the @command{guix environment}
5356 (@pxref{Invoking guix environment}) and @command{guix system container}
5357 (@pxref{Invoking guix system}) commands.
5359 The general syntax is:
5362 guix container @var{action} @var{options}@dots{}
5365 @var{action} specifies the operation to perform with a container, and
5366 @var{options} specifies the context-specific arguments for the action.
5368 The following actions are available:
5372 Execute a command within the context of a running container.
5377 guix container exec @var{pid} @var{program} @var{arguments}@dots{}
5380 @var{pid} specifies the process ID of the running container.
5381 @var{program} specifies an executable file name within the container's
5382 root file system. @var{arguments} are the additional options that will
5383 be passed to @var{program}.
5385 The following command launches an interactive login shell inside a
5386 GuixSD container, started by @command{guix system container}, and whose
5390 guix container exec 9001 /run/current-system/profile/bin/bash --login
5393 Note that the @var{pid} cannot be the parent process of a container. It
5394 must be the container's PID 1 or one of its child processes.
5398 @c *********************************************************************
5399 @node GNU Distribution
5400 @chapter GNU Distribution
5402 @cindex Guix System Distribution
5404 Guix comes with a distribution of the GNU system consisting entirely of
5405 free software@footnote{The term ``free'' here refers to the
5406 @url{http://www.gnu.org/philosophy/free-sw.html,freedom provided to
5407 users of that software}.}. The
5408 distribution can be installed on its own (@pxref{System Installation}),
5409 but it is also possible to install Guix as a package manager on top of
5410 an installed GNU/Linux system (@pxref{Installation}). To distinguish
5411 between the two, we refer to the standalone distribution as the Guix
5412 System Distribution, or GuixSD.
5414 The distribution provides core GNU packages such as GNU libc, GCC, and
5415 Binutils, as well as many GNU and non-GNU applications. The complete
5416 list of available packages can be browsed
5417 @url{http://www.gnu.org/software/guix/packages,on-line} or by
5418 running @command{guix package} (@pxref{Invoking guix package}):
5421 guix package --list-available
5424 Our goal has been to provide a practical 100% free software distribution of
5425 Linux-based and other variants of GNU, with a focus on the promotion and
5426 tight integration of GNU components, and an emphasis on programs and
5427 tools that help users exert that freedom.
5429 Packages are currently available on the following platforms:
5434 Intel/AMD @code{x86_64} architecture, Linux-Libre kernel;
5437 Intel 32-bit architecture (IA32), Linux-Libre kernel;
5440 ARMv7-A architecture with hard float, Thumb-2 and NEON,
5441 using the EABI hard-float ABI, and Linux-Libre kernel.
5443 @item mips64el-linux
5444 little-endian 64-bit MIPS processors, specifically the Loongson series,
5445 n32 application binary interface (ABI), and Linux-Libre kernel.
5449 GuixSD itself is currently only available on @code{i686} and @code{x86_64}.
5452 For information on porting to other architectures or kernels,
5456 * System Installation:: Installing the whole operating system.
5457 * System Configuration:: Configuring the operating system.
5458 * Installing Debugging Files:: Feeding the debugger.
5459 * Security Updates:: Deploying security fixes quickly.
5460 * Package Modules:: Packages from the programmer's viewpoint.
5461 * Packaging Guidelines:: Growing the distribution.
5462 * Bootstrapping:: GNU/Linux built from scratch.
5463 * Porting:: Targeting another platform or kernel.
5466 Building this distribution is a cooperative effort, and you are invited
5467 to join! @xref{Contributing}, for information about how you can help.
5469 @node System Installation
5470 @section System Installation
5472 @cindex Guix System Distribution
5473 This section explains how to install the Guix System Distribution
5474 on a machine. The Guix package manager can
5475 also be installed on top of a running GNU/Linux system,
5476 @pxref{Installation}.
5479 @c This paragraph is for people reading this from tty2 of the
5480 @c installation image.
5481 You're reading this documentation with an Info reader. For details on
5482 how to use it, hit the @key{RET} key (``return'' or ``enter'') on the
5483 link that follows: @pxref{Help,,, info, Info: An Introduction}. Hit
5484 @kbd{l} afterwards to come back here.
5487 @subsection Limitations
5489 As of version @value{VERSION}, the Guix System Distribution (GuixSD) is
5490 not production-ready. It may contain bugs and lack important
5491 features. Thus, if you are looking for a stable production system that
5492 respects your freedom as a computer user, a good solution at this point
5493 is to consider @url{http://www.gnu.org/distros/free-distros.html, one of
5494 more established GNU/Linux distributions}. We hope you can soon switch
5495 to the GuixSD without fear, of course. In the meantime, you can
5496 also keep using your distribution and try out the package manager on top
5497 of it (@pxref{Installation}).
5499 Before you proceed with the installation, be aware of the following
5500 noteworthy limitations applicable to version @value{VERSION}:
5504 The installation process does not include a graphical user interface and
5505 requires familiarity with GNU/Linux (see the following subsections to
5506 get a feel of what that means.)
5509 The system does not yet provide full GNOME and KDE desktops. Xfce and
5510 Enlightenment are available though, if graphical desktop environments
5511 are your thing, as well as a number of X11 window managers.
5514 Support for the Logical Volume Manager (LVM) is missing.
5517 Few system services are currently supported out-of-the-box
5521 More than 2,000 packages are available, but you may
5522 occasionally find that a useful package is missing.
5525 You've been warned. But more than a disclaimer, this is an invitation
5526 to report issues (and success stories!), and join us in improving it.
5527 @xref{Contributing}, for more info.
5529 @subsection USB Stick Installation
5531 An installation image for USB sticks can be downloaded from
5532 @indicateurl{ftp://alpha.gnu.org/gnu/guix/guixsd-usb-install-@value{VERSION}.@var{system}.xz},
5533 where @var{system} is one of:
5537 for a GNU/Linux system on Intel/AMD-compatible 64-bit CPUs;
5540 for a 32-bit GNU/Linux system on Intel-compatible CPUs.
5543 This image contains a single partition with the tools necessary for an
5544 installation. It is meant to be copied @emph{as is} to a large-enough
5547 To copy the image to a USB stick, follow these steps:
5551 Decompress the image using the @command{xz} command:
5554 xz -d guixsd-usb-install-@value{VERSION}.@var{system}.xz
5558 Insert a USB stick of 1@tie{}GiB or more in your machine, and determine
5559 its device name. Assuming that USB stick is known as @file{/dev/sdX},
5560 copy the image with:
5563 dd if=guixsd-usb-install-@value{VERSION}.x86_64 of=/dev/sdX
5566 Access to @file{/dev/sdX} usually requires root privileges.
5569 Once this is done, you should be able to reboot the system and boot from
5570 the USB stick. The latter usually requires you to get in the BIOS' boot
5571 menu, where you can choose to boot from the USB stick.
5573 @subsection Preparing for Installation
5575 Once you have successfully booted the image on the USB stick, you should
5576 end up with a root prompt. Several console TTYs are configured and can
5577 be used to run commands as root. TTY2 shows this documentation,
5578 browsable using the Info reader commands (@pxref{Help,,, info, Info: An
5579 Introduction}). The installation system runs the GPM mouse daemon,
5580 which allows you to select text with the left mouse button and to paste
5581 it with the middle button.
5583 To install the system, you would:
5588 Configure the network, by running:
5591 ifconfig eno1 up && dhclient eno1
5594 to get an automatically assigned IP address from the wired
5595 network interface controller@footnote{
5596 @c http://cgit.freedesktop.org/systemd/systemd/tree/src/udev/udev-builtin-net_id.c#n20
5597 The name @code{eno1} is for the first on-board Ethernet controller. The
5598 interface name for an Ethernet controller that is in the first slot of
5599 the first PCI bus, for instance, would be @code{enp1s0}. Use
5600 @command{ifconfig -a} to list all the available network interfaces.},
5601 or using the @command{ifconfig} command.
5603 The system automatically loads drivers for your network interface
5606 Setting up network access is almost always a requirement because the
5607 image does not contain all the software and tools that may be needed.
5610 Unless this has already been done, you must partition, and then format
5611 the target partition.
5613 Preferably, assign partitions a label so that you can easily and
5614 reliably refer to them in @code{file-system} declarations (@pxref{File
5615 Systems}). This is typically done using the @code{-L} option of
5616 @command{mkfs.ext4} and related commands.
5618 Be sure that your partition labels match the value of their respective
5619 @code{device} fields in your @code{file-system} configuration, if your
5620 @code{file-system} configuration sets the value of @code{title} to
5621 @code{'label}, as do the example configurations found on the USB
5622 installation image under @file{/etc/configuration} (@pxref{Using the
5623 Configuration System}).
5625 @c FIXME: Uncomment this once GRUB fully supports encrypted roots.
5626 @c A typical command sequence may be:
5630 @c @dots{} Create partitions etc.@dots{}
5631 @c # cryptsetup luksFormat /dev/sdX1
5632 @c # cryptsetup open --type luks /dev/sdX1 my-partition
5633 @c # mkfs.ext4 -L my-root /dev/mapper/my-partition
5636 The installation image includes Parted (@pxref{Overview,,, parted, GNU
5637 Parted User Manual}), @command{fdisk}, Cryptsetup/LUKS for disk
5638 encryption, and e2fsprogs, the suite of tools to manipulate
5639 ext2/ext3/ext4 file systems.
5642 Once that is done, mount the target root partition under @file{/mnt}.
5645 Lastly, run @code{herd start cow-store /mnt}.
5647 This will make @file{/gnu/store} copy-on-write, such that packages added
5648 to it during the installation phase will be written to the target disk
5649 rather than kept in memory.
5654 @subsection Proceeding with the Installation
5656 With the target partitions ready, you now have to edit a file and
5657 provide the declaration of the operating system to be installed. To
5658 that end, the installation system comes with two text editors: GNU nano
5659 (@pxref{Top,,, nano, GNU nano Manual}), and GNU Zile, an Emacs clone.
5660 It is better to store that file on the target root file system, say, as
5661 @file{/mnt/etc/config.scm}.
5663 @xref{Using the Configuration System}, for examples of operating system
5664 configurations. These examples are available under
5665 @file{/etc/configuration} in the installation image, so you can copy
5666 them and use them as a starting point for your own configuration.
5668 Once you are done preparing the configuration file, the new system must
5669 be initialized (remember that the target root file system is mounted
5673 guix system init /mnt/etc/config.scm /mnt
5677 This will copy all the necessary files, and install GRUB on
5678 @file{/dev/sdX}, unless you pass the @option{--no-grub} option. For
5679 more information, @pxref{Invoking guix system}. This command may trigger
5680 downloads or builds of missing packages, which can take some time.
5682 Once that command has completed---and hopefully succeeded!---you can run
5683 @command{reboot} and boot into the new system. The @code{root} password
5684 in the new system is initially empty; other users' passwords need to be
5685 initialized by running the @command{passwd} command as @code{root},
5686 unless your configuration specifies otherwise
5687 (@pxref{user-account-password, user account passwords}).
5689 Join us on @code{#guix} on the Freenode IRC network or on
5690 @file{guix-devel@@gnu.org} to share your experience---good or not so
5693 @subsection Building the Installation Image
5695 The installation image described above was built using the @command{guix
5696 system} command, specifically:
5699 guix system disk-image --image-size=850MiB gnu/system/install.scm
5702 @xref{Invoking guix system}, for more information. See
5703 @file{gnu/system/install.scm} in the source tree for more information
5704 about the installation image.
5706 @node System Configuration
5707 @section System Configuration
5709 @cindex system configuration
5710 The Guix System Distribution supports a consistent whole-system configuration
5711 mechanism. By that we mean that all aspects of the global system
5712 configuration---such as the available system services, timezone and
5713 locale settings, user accounts---are declared in a single place. Such
5714 a @dfn{system configuration} can be @dfn{instantiated}---i.e., effected.
5716 One of the advantages of putting all the system configuration under the
5717 control of Guix is that it supports transactional system upgrades, and
5718 makes it possible to roll-back to a previous system instantiation,
5719 should something go wrong with the new one (@pxref{Features}). Another
5720 one is that it makes it easy to replicate the exact same configuration
5721 across different machines, or at different points in time, without
5722 having to resort to additional administration tools layered on top of
5723 the system's own tools.
5724 @c Yes, we're talking of Puppet, Chef, & co. here. ↑
5726 This section describes this mechanism. First we focus on the system
5727 administrator's viewpoint---explaining how the system is configured and
5728 instantiated. Then we show how this mechanism can be extended, for
5729 instance to support new system services.
5732 * Using the Configuration System:: Customizing your GNU system.
5733 * operating-system Reference:: Detail of operating-system declarations.
5734 * File Systems:: Configuring file system mounts.
5735 * Mapped Devices:: Block device extra processing.
5736 * User Accounts:: Specifying user accounts.
5737 * Locales:: Language and cultural convention settings.
5738 * Services:: Specifying system services.
5739 * Setuid Programs:: Programs running with root privileges.
5740 * X.509 Certificates:: Authenticating HTTPS servers.
5741 * Name Service Switch:: Configuring libc's name service switch.
5742 * Initial RAM Disk:: Linux-Libre bootstrapping.
5743 * GRUB Configuration:: Configuring the boot loader.
5744 * Invoking guix system:: Instantiating a system configuration.
5745 * Running GuixSD in a VM:: How to run GuixSD in a virtual machine.
5746 * Defining Services:: Adding new service definitions.
5749 @node Using the Configuration System
5750 @subsection Using the Configuration System
5752 The operating system is configured by providing an
5753 @code{operating-system} declaration in a file that can then be passed to
5754 the @command{guix system} command (@pxref{Invoking guix system}). A
5755 simple setup, with the default system services, the default Linux-Libre
5756 kernel, initial RAM disk, and boot loader looks like this:
5758 @findex operating-system
5760 @include os-config-bare-bones.texi
5763 This example should be self-describing. Some of the fields defined
5764 above, such as @code{host-name} and @code{bootloader}, are mandatory.
5765 Others, such as @code{packages} and @code{services}, can be omitted, in
5766 which case they get a default value.
5768 Below we discuss the effect of some of the most important fields
5769 (@pxref{operating-system Reference}, for details about all the available
5770 fields), and how to @dfn{instantiate} the operating system using
5771 @command{guix system}.
5773 @unnumberedsubsubsec Globally-Visible Packages
5775 @vindex %base-packages
5776 The @code{packages} field lists packages that will be globally visible
5777 on the system, for all user accounts---i.e., in every user's @code{PATH}
5778 environment variable---in addition to the per-user profiles
5779 (@pxref{Invoking guix package}). The @var{%base-packages} variable
5780 provides all the tools one would expect for basic user and administrator
5781 tasks---including the GNU Core Utilities, the GNU Networking Utilities,
5782 the GNU Zile lightweight text editor, @command{find}, @command{grep},
5783 etc. The example above adds tcpdump to those, taken from the @code{(gnu
5784 packages admin)} module (@pxref{Package Modules}).
5786 @findex specification->package
5787 Referring to packages by variable name, like @var{tcpdump} above, has
5788 the advantage of being unambiguous; it also allows typos and such to be
5789 diagnosed right away as ``unbound variables''. The downside is that one
5790 needs to know which module defines which package, and to augment the
5791 @code{use-package-modules} line accordingly. To avoid that, one can use
5792 the @code{specification->package} procedure of the @code{(gnu packages)}
5793 module, which returns the best package for a given name or name and
5797 (use-modules (gnu packages))
5801 (packages (append (map specification->package
5802 '("tcpdump" "htop" "gnupg-2.0"))
5806 @unnumberedsubsubsec System Services
5808 @vindex %base-services
5809 The @code{services} field lists @dfn{system services} to be made
5810 available when the system starts (@pxref{Services}).
5811 The @code{operating-system} declaration above specifies that, in
5812 addition to the basic services, we want the @command{lshd} secure shell
5813 daemon listening on port 2222 (@pxref{Networking Services,
5814 @code{lsh-service}}). Under the hood,
5815 @code{lsh-service} arranges so that @code{lshd} is started with the
5816 right command-line options, possibly with supporting configuration files
5817 generated as needed (@pxref{Defining Services}).
5819 @cindex customization, of services
5820 @findex modify-services
5821 Occasionally, instead of using the base services as is, you will want to
5822 customize them. For instance, to change the configuration of
5823 @code{guix-daemon} and Mingetty (the console log-in), you may write the
5824 following instead of @var{%base-services}:
5827 (modify-services %base-services
5828 (guix-service-type config =>
5831 (use-substitutes? #f)
5832 (extra-options '("--gc-keep-outputs"))))
5833 (mingetty-service-type config =>
5834 (mingetty-configuration
5836 (motd (plain-file "motd" "Hi there!")))))
5840 The effect here is to change the options passed to @command{guix-daemon}
5841 when it is started, as well as the ``message of the day'' that appears
5842 when logging in at the console. @xref{Service Reference,
5843 @code{modify-services}}, for more on that.
5845 The configuration for a typical ``desktop'' usage, with the X11 display
5846 server, a desktop environment, network management, power management, and
5847 more, would look like this:
5850 @include os-config-desktop.texi
5853 @xref{Desktop Services}, for the exact list of services provided by
5854 @var{%desktop-services}. @xref{X.509 Certificates}, for background
5855 information about the @code{nss-certs} package that is used here.
5857 Again, @var{%desktop-services} is just a list of service objects. If
5858 you want to remove services from there, you can do so using the
5859 procedures for list filtering (@pxref{SRFI-1 Filtering and
5860 Partitioning,,, guile, GNU Guile Reference Manual}). For instance, the
5861 following expression returns a list that contains all the services in
5862 @var{%desktop-services} minus the Avahi service:
5865 (remove (lambda (service)
5866 (eq? (service-kind service) avahi-service-type))
5870 @unnumberedsubsubsec Instantiating the System
5872 Assuming the @code{operating-system} declaration
5873 is stored in the @file{my-system-config.scm}
5874 file, the @command{guix system reconfigure my-system-config.scm} command
5875 instantiates that configuration, and makes it the default GRUB boot
5876 entry (@pxref{Invoking guix system}).
5878 The normal way to change the system's configuration is by updating this
5879 file and re-running @command{guix system reconfigure}. One should never
5880 have to touch files in @command{/etc} or to run commands that modify the
5881 system state such as @command{useradd} or @command{grub-install}. In
5882 fact, you must avoid that since that would not only void your warranty
5883 but also prevent you from rolling back to previous versions of your
5884 system, should you ever need to.
5886 @cindex roll-back, of the operating system
5887 Speaking of roll-back, each time you run @command{guix system
5888 reconfigure}, a new @dfn{generation} of the system is created---without
5889 modifying or deleting previous generations. Old system generations get
5890 an entry in the GRUB boot menu, allowing you to boot them in case
5891 something went wrong with the latest generation. Reassuring, no? The
5892 @command{guix system list-generations} command lists the system
5893 generations available on disk.
5895 @unnumberedsubsubsec The Programming Interface
5897 At the Scheme level, the bulk of an @code{operating-system} declaration
5898 is instantiated with the following monadic procedure (@pxref{The Store
5901 @deffn {Monadic Procedure} operating-system-derivation os
5902 Return a derivation that builds @var{os}, an @code{operating-system}
5903 object (@pxref{Derivations}).
5905 The output of the derivation is a single directory that refers to all
5906 the packages, configuration files, and other supporting files needed to
5907 instantiate @var{os}.
5910 This procedure is provided by the @code{(gnu system)} module. Along
5911 with @code{(gnu services)} (@pxref{Services}), this module contains the
5912 guts of GuixSD. Make sure to visit it!
5915 @node operating-system Reference
5916 @subsection @code{operating-system} Reference
5918 This section summarizes all the options available in
5919 @code{operating-system} declarations (@pxref{Using the Configuration
5922 @deftp {Data Type} operating-system
5923 This is the data type representing an operating system configuration.
5924 By that, we mean all the global system configuration, not per-user
5925 configuration (@pxref{Using the Configuration System}).
5928 @item @code{kernel} (default: @var{linux-libre})
5929 The package object of the operating system kernel to use@footnote{Currently
5930 only the Linux-libre kernel is supported. In the future, it will be
5931 possible to use the GNU@tie{}Hurd.}.
5933 @item @code{kernel-arguments} (default: @code{'()})
5934 List of strings or gexps representing additional arguments to pass on
5935 the kernel's command-line---e.g., @code{("console=ttyS0")}.
5937 @item @code{bootloader}
5938 The system bootloader configuration object. @xref{GRUB Configuration}.
5940 @item @code{initrd} (default: @code{base-initrd})
5941 A two-argument monadic procedure that returns an initial RAM disk for
5942 the Linux kernel. @xref{Initial RAM Disk}.
5944 @item @code{firmware} (default: @var{%base-firmware})
5946 List of firmware packages loadable by the operating system kernel.
5948 The default includes firmware needed for Atheros-based WiFi devices
5949 (Linux-libre module @code{ath9k}.)
5951 @item @code{host-name}
5954 @item @code{hosts-file}
5956 A file-like object (@pxref{G-Expressions, file-like objects}) for use as
5957 @file{/etc/hosts} (@pxref{Host Names,,, libc, The GNU C Library
5958 Reference Manual}). The default is a file with entries for
5959 @code{localhost} and @var{host-name}.
5961 @item @code{mapped-devices} (default: @code{'()})
5962 A list of mapped devices. @xref{Mapped Devices}.
5964 @item @code{file-systems}
5965 A list of file systems. @xref{File Systems}.
5967 @item @code{swap-devices} (default: @code{'()})
5968 @cindex swap devices
5969 A list of strings identifying devices to be used for ``swap space''
5970 (@pxref{Memory Concepts,,, libc, The GNU C Library Reference Manual}).
5971 For example, @code{'("/dev/sda3")}.
5973 @item @code{users} (default: @code{%base-user-accounts})
5974 @itemx @code{groups} (default: @var{%base-groups})
5975 List of user accounts and groups. @xref{User Accounts}.
5977 @item @code{skeletons} (default: @code{(default-skeletons)})
5978 A monadic list of pairs of target file name and files. These are the
5979 files that will be used as skeletons as new accounts are created.
5981 For instance, a valid value may look like this:
5984 (mlet %store-monad ((bashrc (text-file "bashrc" "\
5985 export PATH=$HOME/.guix-profile/bin")))
5986 (return `((".bashrc" ,bashrc))))
5989 @item @code{issue} (default: @var{%default-issue})
5990 A string denoting the contents of the @file{/etc/issue} file, which is
5991 what displayed when users log in on a text console.
5993 @item @code{packages} (default: @var{%base-packages})
5994 The set of packages installed in the global profile, which is accessible
5995 at @file{/run/current-system/profile}.
5997 The default set includes core utilities, but it is good practice to
5998 install non-core utilities in user profiles (@pxref{Invoking guix
6001 @item @code{timezone}
6002 A timezone identifying string---e.g., @code{"Europe/Paris"}.
6004 @item @code{locale} (default: @code{"en_US.utf8"})
6005 The name of the default locale (@pxref{Locale Names,,, libc, The GNU C
6006 Library Reference Manual}). @xref{Locales}, for more information.
6008 @item @code{locale-definitions} (default: @var{%default-locale-definitions})
6009 The list of locale definitions to be compiled and that may be used at
6010 run time. @xref{Locales}.
6012 @item @code{locale-libcs} (default: @code{(list @var{glibc})})
6013 The list of GNU@tie{}libc packages whose locale data and tools are used
6014 to build the locale definitions. @xref{Locales}, for compatibility
6015 considerations that justify this option.
6017 @item @code{name-service-switch} (default: @var{%default-nss})
6018 Configuration of libc's name service switch (NSS)---a
6019 @code{<name-service-switch>} object. @xref{Name Service Switch}, for
6022 @item @code{services} (default: @var{%base-services})
6023 A list of service objects denoting system services. @xref{Services}.
6025 @item @code{pam-services} (default: @code{(base-pam-services)})
6027 @cindex pluggable authentication modules
6028 Linux @dfn{pluggable authentication module} (PAM) services.
6029 @c FIXME: Add xref to PAM services section.
6031 @item @code{setuid-programs} (default: @var{%setuid-programs})
6032 List of string-valued G-expressions denoting setuid programs.
6033 @xref{Setuid Programs}.
6035 @item @code{sudoers-file} (default: @var{%sudoers-specification})
6036 @cindex sudoers file
6037 The contents of the @file{/etc/sudoers} file as a file-like object
6038 (@pxref{G-Expressions, @code{local-file} and @code{plain-file}}).
6040 This file specifies which users can use the @command{sudo} command, what
6041 they are allowed to do, and what privileges they may gain. The default
6042 is that only @code{root} and members of the @code{wheel} group may use
6049 @subsection File Systems
6051 The list of file systems to be mounted is specified in the
6052 @code{file-systems} field of the operating system's declaration
6053 (@pxref{Using the Configuration System}). Each file system is declared
6054 using the @code{file-system} form, like this:
6058 (mount-point "/home")
6059 (device "/dev/sda3")
6063 As usual, some of the fields are mandatory---those shown in the example
6064 above---while others can be omitted. These are described below.
6066 @deftp {Data Type} file-system
6067 Objects of this type represent file systems to be mounted. They
6068 contain the following members:
6072 This is a string specifying the type of the file system---e.g.,
6075 @item @code{mount-point}
6076 This designates the place where the file system is to be mounted.
6079 This names the ``source'' of the file system. By default it is the name
6080 of a node under @file{/dev}, but its meaning depends on the @code{title}
6081 field described below.
6083 @item @code{title} (default: @code{'device})
6084 This is a symbol that specifies how the @code{device} field is to be
6087 When it is the symbol @code{device}, then the @code{device} field is
6088 interpreted as a file name; when it is @code{label}, then @code{device}
6089 is interpreted as a partition label name; when it is @code{uuid},
6090 @code{device} is interpreted as a partition unique identifier (UUID).
6092 UUIDs may be converted from their string representation (as shown by the
6093 @command{tune2fs -l} command) using the @code{uuid} form, like this:
6097 (mount-point "/home")
6100 (device (uuid "4dab5feb-d176-45de-b287-9b0a6e4c01cb")))
6103 The @code{label} and @code{uuid} options offer a way to refer to disk
6104 partitions without having to hard-code their actual device
6105 name@footnote{Note that, while it is tempting to use
6106 @file{/dev/disk/by-uuid} and similar device names to achieve the same
6107 result, this is not recommended: These special device nodes are created
6108 by the udev daemon and may be unavailable at the time the device is
6111 However, when a file system's source is a mapped device (@pxref{Mapped
6112 Devices}), its @code{device} field @emph{must} refer to the mapped
6113 device name---e.g., @file{/dev/mapper/root-partition}---and consequently
6114 @code{title} must be set to @code{'device}. This is required so that
6115 the system knows that mounting the file system depends on having the
6116 corresponding device mapping established.
6118 @item @code{flags} (default: @code{'()})
6119 This is a list of symbols denoting mount flags. Recognized flags
6120 include @code{read-only}, @code{bind-mount}, @code{no-dev} (disallow
6121 access to special files), @code{no-suid} (ignore setuid and setgid
6122 bits), and @code{no-exec} (disallow program execution.)
6124 @item @code{options} (default: @code{#f})
6125 This is either @code{#f}, or a string denoting mount options.
6127 @item @code{mount?} (default: @code{#t})
6128 This value indicates whether to automatically mount the file system when
6129 the system is brought up. When set to @code{#f}, the file system gets
6130 an entry in @file{/etc/fstab} (read by the @command{mount} command) but
6131 is not automatically mounted.
6133 @item @code{needed-for-boot?} (default: @code{#f})
6134 This Boolean value indicates whether the file system is needed when
6135 booting. If that is true, then the file system is mounted when the
6136 initial RAM disk (initrd) is loaded. This is always the case, for
6137 instance, for the root file system.
6139 @item @code{check?} (default: @code{#t})
6140 This Boolean indicates whether the file system needs to be checked for
6141 errors before being mounted.
6143 @item @code{create-mount-point?} (default: @code{#f})
6144 When true, the mount point is created if it does not exist yet.
6146 @item @code{dependencies} (default: @code{'()})
6147 This is a list of @code{<file-system>} objects representing file systems
6148 that must be mounted before (and unmounted after) this one.
6150 As an example, consider a hierarchy of mounts: @file{/sys/fs/cgroup} is
6151 a dependency of @file{/sys/fs/cgroup/cpu} and
6152 @file{/sys/fs/cgroup/memory}.
6157 The @code{(gnu system file-systems)} exports the following useful
6160 @defvr {Scheme Variable} %base-file-systems
6161 These are essential file systems that are required on normal systems,
6162 such as @var{%pseudo-terminal-file-system} and @var{%immutable-store} (see
6163 below.) Operating system declarations should always contain at least
6167 @defvr {Scheme Variable} %pseudo-terminal-file-system
6168 This is the file system to be mounted as @file{/dev/pts}. It supports
6169 @dfn{pseudo-terminals} created @i{via} @code{openpty} and similar
6170 functions (@pxref{Pseudo-Terminals,,, libc, The GNU C Library Reference
6171 Manual}). Pseudo-terminals are used by terminal emulators such as
6175 @defvr {Scheme Variable} %shared-memory-file-system
6176 This file system is mounted as @file{/dev/shm} and is used to support
6177 memory sharing across processes (@pxref{Memory-mapped I/O,
6178 @code{shm_open},, libc, The GNU C Library Reference Manual}).
6181 @defvr {Scheme Variable} %immutable-store
6182 This file system performs a read-only ``bind mount'' of
6183 @file{/gnu/store}, making it read-only for all the users including
6184 @code{root}. This prevents against accidental modification by software
6185 running as @code{root} or by system administrators.
6187 The daemon itself is still able to write to the store: it remounts it
6188 read-write in its own ``name space.''
6191 @defvr {Scheme Variable} %binary-format-file-system
6192 The @code{binfmt_misc} file system, which allows handling of arbitrary
6193 executable file types to be delegated to user space. This requires the
6194 @code{binfmt.ko} kernel module to be loaded.
6197 @defvr {Scheme Variable} %fuse-control-file-system
6198 The @code{fusectl} file system, which allows unprivileged users to mount
6199 and unmount user-space FUSE file systems. This requires the
6200 @code{fuse.ko} kernel module to be loaded.
6203 @node Mapped Devices
6204 @subsection Mapped Devices
6206 @cindex device mapping
6207 @cindex mapped devices
6208 The Linux kernel has a notion of @dfn{device mapping}: a block device,
6209 such as a hard disk partition, can be @dfn{mapped} into another device,
6210 with additional processing over the data that flows through
6211 it@footnote{Note that the GNU@tie{}Hurd makes no difference between the
6212 concept of a ``mapped device'' and that of a file system: both boil down
6213 to @emph{translating} input/output operations made on a file to
6214 operations on its backing store. Thus, the Hurd implements mapped
6215 devices, like file systems, using the generic @dfn{translator} mechanism
6216 (@pxref{Translators,,, hurd, The GNU Hurd Reference Manual}).}. A
6217 typical example is encryption device mapping: all writes to the mapped
6218 device are encrypted, and all reads are deciphered, transparently.
6220 Mapped devices are declared using the @code{mapped-device} form:
6224 (source "/dev/sda3")
6226 (type luks-device-mapping))
6230 @cindex disk encryption
6232 This example specifies a mapping from @file{/dev/sda3} to
6233 @file{/dev/mapper/home} using LUKS---the
6234 @url{http://code.google.com/p/cryptsetup,Linux Unified Key Setup}, a
6235 standard mechanism for disk encryption. The @file{/dev/mapper/home}
6236 device can then be used as the @code{device} of a @code{file-system}
6237 declaration (@pxref{File Systems}). The @code{mapped-device} form is
6240 @deftp {Data Type} mapped-device
6241 Objects of this type represent device mappings that will be made when
6242 the system boots up.
6246 This string specifies the name of the block device to be mapped, such as
6250 This string specifies the name of the mapping to be established. For
6251 example, specifying @code{"my-partition"} will lead to the creation of
6252 the @code{"/dev/mapper/my-partition"} device.
6255 This must be a @code{mapped-device-kind} object, which specifies how
6256 @var{source} is mapped to @var{target}.
6260 @defvr {Scheme Variable} luks-device-mapping
6261 This defines LUKS block device encryption using the @command{cryptsetup}
6262 command, from the same-named package. This relies on the
6263 @code{dm-crypt} Linux kernel module.
6267 @subsection User Accounts
6269 User accounts and groups are entirely managed through the
6270 @code{operating-system} declaration. They are specified with the
6271 @code{user-account} and @code{user-group} forms:
6277 (supplementary-groups '("wheel" ;allow use of sudo, etc.
6279 "video" ;video devices such as webcams
6280 "cdrom")) ;the good ol' CD-ROM
6281 (comment "Bob's sister")
6282 (home-directory "/home/alice"))
6285 When booting or upon completion of @command{guix system reconfigure},
6286 the system ensures that only the user accounts and groups specified in
6287 the @code{operating-system} declaration exist, and with the specified
6288 properties. Thus, account or group creations or modifications made by
6289 directly invoking commands such as @command{useradd} are lost upon
6290 reconfiguration or reboot. This ensures that the system remains exactly
6293 @deftp {Data Type} user-account
6294 Objects of this type represent user accounts. The following members may
6299 The name of the user account.
6302 This is the name (a string) or identifier (a number) of the user group
6303 this account belongs to.
6305 @item @code{supplementary-groups} (default: @code{'()})
6306 Optionally, this can be defined as a list of group names that this
6309 @item @code{uid} (default: @code{#f})
6310 This is the user ID for this account (a number), or @code{#f}. In the
6311 latter case, a number is automatically chosen by the system when the
6314 @item @code{comment} (default: @code{""})
6315 A comment about the account, such as the account's owner full name.
6317 @item @code{home-directory}
6318 This is the name of the home directory for the account.
6320 @item @code{shell} (default: Bash)
6321 This is a G-expression denoting the file name of a program to be used as
6322 the shell (@pxref{G-Expressions}).
6324 @item @code{system?} (default: @code{#f})
6325 This Boolean value indicates whether the account is a ``system''
6326 account. System accounts are sometimes treated specially; for instance,
6327 graphical login managers do not list them.
6329 @anchor{user-account-password}
6330 @item @code{password} (default: @code{#f})
6331 You would normally leave this field to @code{#f}, initialize user
6332 passwords as @code{root} with the @command{passwd} command, and then let
6333 users change it with @command{passwd}. Passwords set with
6334 @command{passwd} are of course preserved across reboot and
6337 If you @emph{do} want to have a preset password for an account, then
6338 this field must contain the encrypted password, as a string.
6339 @xref{crypt,,, libc, The GNU C Library Reference Manual}, for more information
6340 on password encryption, and @ref{Encryption,,, guile, GNU Guile Reference
6341 Manual}, for information on Guile's @code{crypt} procedure.
6346 User group declarations are even simpler:
6349 (user-group (name "students"))
6352 @deftp {Data Type} user-group
6353 This type is for, well, user groups. There are just a few fields:
6359 @item @code{id} (default: @code{#f})
6360 The group identifier (a number). If @code{#f}, a new number is
6361 automatically allocated when the group is created.
6363 @item @code{system?} (default: @code{#f})
6364 This Boolean value indicates whether the group is a ``system'' group.
6365 System groups have low numerical IDs.
6367 @item @code{password} (default: @code{#f})
6368 What, user groups can have a password? Well, apparently yes. Unless
6369 @code{#f}, this field specifies the group's password.
6374 For convenience, a variable lists all the basic user groups one may
6377 @defvr {Scheme Variable} %base-groups
6378 This is the list of basic user groups that users and/or packages expect
6379 to be present on the system. This includes groups such as ``root'',
6380 ``wheel'', and ``users'', as well as groups used to control access to
6381 specific devices such as ``audio'', ``disk'', and ``cdrom''.
6384 @defvr {Scheme Variable} %base-user-accounts
6385 This is the list of basic system accounts that programs may expect to
6386 find on a GNU/Linux system, such as the ``nobody'' account.
6388 Note that the ``root'' account is not included here. It is a
6389 special-case and is automatically added whether or not it is specified.
6396 A @dfn{locale} defines cultural conventions for a particular language
6397 and region of the world (@pxref{Locales,,, libc, The GNU C Library
6398 Reference Manual}). Each locale has a name that typically has the form
6399 @code{@var{language}_@var{territory}.@var{codeset}}---e.g.,
6400 @code{fr_LU.utf8} designates the locale for the French language, with
6401 cultural conventions from Luxembourg, and using the UTF-8 encoding.
6403 @cindex locale definition
6404 Usually, you will want to specify the default locale for the machine
6405 using the @code{locale} field of the @code{operating-system} declaration
6406 (@pxref{operating-system Reference, @code{locale}}).
6408 That locale must be among the @dfn{locale definitions} that are known to
6409 the system---and these are specified in the @code{locale-definitions}
6410 slot of @code{operating-system}. The default value includes locale
6411 definitions for some widely used locales, but not for all the available
6412 locales, in order to save space.
6414 If the locale specified in the @code{locale} field is not among the
6415 definitions listed in @code{locale-definitions}, @command{guix system}
6416 raises an error. In that case, you should add the locale definition to
6417 the @code{locale-definitions} field. For instance, to add the North
6418 Frisian locale for Germany, the value of that field may be:
6421 (cons (locale-definition
6422 (name "fy_DE.utf8") (source "fy_DE"))
6423 %default-locale-definitions)
6426 Likewise, to save space, one might want @code{locale-definitions} to
6427 list only the locales that are actually used, as in:
6430 (list (locale-definition
6431 (name "ja_JP.eucjp") (source "ja_JP")
6432 (charset "EUC-JP")))
6436 The compiled locale definitions are available at
6437 @file{/run/current-system/locale/X.Y}, where @code{X.Y} is the libc
6438 version, which is the default location where the GNU@tie{}libc provided
6439 by Guix looks for locale data. This can be overridden using the
6440 @code{LOCPATH} environment variable (@pxref{locales-and-locpath,
6441 @code{LOCPATH} and locale packages}).
6443 The @code{locale-definition} form is provided by the @code{(gnu system
6444 locale)} module. Details are given below.
6446 @deftp {Data Type} locale-definition
6447 This is the data type of a locale definition.
6452 The name of the locale. @xref{Locale Names,,, libc, The GNU C Library
6453 Reference Manual}, for more information on locale names.
6456 The name of the source for that locale. This is typically the
6457 @code{@var{language}_@var{territory}} part of the locale name.
6459 @item @code{charset} (default: @code{"UTF-8"})
6460 The ``character set'' or ``code set'' for that locale,
6461 @uref{http://www.iana.org/assignments/character-sets, as defined by
6467 @defvr {Scheme Variable} %default-locale-definitions
6468 An arbitrary list of commonly used UTF-8 locales, used as the default
6469 value of the @code{locale-definitions} field of @code{operating-system}
6473 @cindex normalized codeset in locale names
6474 These locale definitions use the @dfn{normalized codeset} for the part
6475 that follows the dot in the name (@pxref{Using gettextized software,
6476 normalized codeset,, libc, The GNU C Library Reference Manual}). So for
6477 instance it has @code{uk_UA.utf8} but @emph{not}, say,
6481 @subsubsection Locale Data Compatibility Considerations
6483 @cindex incompatibility, of locale data
6484 @code{operating-system} declarations provide a @code{locale-libcs} field
6485 to specify the GNU@tie{}libc packages that are used to compile locale
6486 declarations (@pxref{operating-system Reference}). ``Why would I
6487 care?'', you may ask. Well, it turns out that the binary format of
6488 locale data is occasionally incompatible from one libc version to
6491 @c See <https://sourceware.org/ml/libc-alpha/2015-09/msg00575.html>
6492 @c and <https://lists.gnu.org/archive/html/guix-devel/2015-08/msg00737.html>.
6493 For instance, a program linked against libc version 2.21 is unable to
6494 read locale data produced with libc 2.22; worse, that program
6495 @emph{aborts} instead of simply ignoring the incompatible locale
6496 data@footnote{Versions 2.23 and later of GNU@tie{}libc will simply skip
6497 the incompatible locale data, which is already an improvement.}.
6498 Similarly, a program linked against libc 2.22 can read most, but not
6499 all, the locale data from libc 2.21 (specifically, @code{LC_COLLATE}
6500 data is incompatible); thus calls to @code{setlocale} may fail, but
6501 programs will not abort.
6503 The ``problem'' in GuixSD is that users have a lot of freedom: They can
6504 choose whether and when to upgrade software in their profiles, and might
6505 be using a libc version different from the one the system administrator
6506 used to build the system-wide locale data.
6508 Fortunately, unprivileged users can also install their own locale data
6509 and define @var{GUIX_LOCPATH} accordingly (@pxref{locales-and-locpath,
6510 @code{GUIX_LOCPATH} and locale packages}).
6512 Still, it is best if the system-wide locale data at
6513 @file{/run/current-system/locale} is built for all the libc versions
6514 actually in use on the system, so that all the programs can access
6515 it---this is especially crucial on a multi-user system. To do that, the
6516 administrator can specify several libc packages in the
6517 @code{locale-libcs} field of @code{operating-system}:
6520 (use-package-modules base)
6524 (locale-libcs (list glibc-2.21 (canonical-package glibc))))
6527 This example would lead to a system containing locale definitions for
6528 both libc 2.21 and the current version of libc in
6529 @file{/run/current-system/locale}.
6533 @subsection Services
6535 @cindex system services
6536 An important part of preparing an @code{operating-system} declaration is
6537 listing @dfn{system services} and their configuration (@pxref{Using the
6538 Configuration System}). System services are typically daemons launched
6539 when the system boots, or other actions needed at that time---e.g.,
6540 configuring network access.
6542 Services are managed by the GNU@tie{}Shepherd (@pxref{Introduction,,,
6543 shepherd, The GNU Shepherd Manual}). On a running system, the
6544 @command{herd} command allows you to list the available services, show
6545 their status, start and stop them, or do other specific operations
6546 (@pxref{Jump Start,,, shepherd, The GNU Shepherd Manual}). For example:
6552 The above command, run as @code{root}, lists the currently defined
6553 services. The @command{herd doc} command shows a synopsis of the given
6558 Run libc's name service cache daemon (nscd).
6561 The @command{start}, @command{stop}, and @command{restart} sub-commands
6562 have the effect you would expect. For instance, the commands below stop
6563 the nscd service and restart the Xorg display server:
6567 Service nscd has been stopped.
6568 # herd restart xorg-server
6569 Service xorg-server has been stopped.
6570 Service xorg-server has been started.
6573 The following sections document the available services, starting with
6574 the core services, that may be used in an @code{operating-system}
6578 * Base Services:: Essential system services.
6579 * Networking Services:: Network setup, SSH daemon, etc.
6580 * X Window:: Graphical display.
6581 * Desktop Services:: D-Bus and desktop services.
6582 * Database Services:: SQL databases.
6583 * Mail Services:: IMAP, POP3, SMTP, and all that.
6584 * Web Services:: Web servers.
6585 * Various Services:: Other services.
6589 @subsubsection Base Services
6591 The @code{(gnu services base)} module provides definitions for the basic
6592 services that one expects from the system. The services exported by
6593 this module are listed below.
6595 @defvr {Scheme Variable} %base-services
6596 This variable contains a list of basic services (@pxref{Service Types
6597 and Services}, for more information on service objects) one would
6598 expect from the system: a login service (mingetty) on each tty, syslogd,
6599 libc's name service cache daemon (nscd), the udev device manager, and
6602 This is the default value of the @code{services} field of
6603 @code{operating-system} declarations. Usually, when customizing a
6604 system, you will want to append services to @var{%base-services}, like
6608 (cons* (avahi-service) (lsh-service) %base-services)
6612 @deffn {Scheme Procedure} host-name-service @var{name}
6613 Return a service that sets the host name to @var{name}.
6616 @deffn {Scheme Procedure} mingetty-service @var{config}
6617 Return a service to run mingetty according to @var{config}, a
6618 @code{<mingetty-configuration>} object, which specifies the tty to run, among
6622 @deftp {Data Type} mingetty-configuration
6623 This is the data type representing the configuration of Mingetty, which
6624 implements console log-in.
6629 The name of the console this Mingetty runs on---e.g., @code{"tty1"}.
6632 A file-like object containing the ``message of the day''.
6634 @item @code{auto-login} (default: @code{#f})
6635 When true, this field must be a string denoting the user name under
6636 which the system automatically logs in. When it is @code{#f}, a
6637 user name and password must be entered to log in.
6639 @item @code{login-program} (default: @code{#f})
6640 This must be either @code{#f}, in which case the default log-in program
6641 is used (@command{login} from the Shadow tool suite), or a gexp denoting
6642 the name of the log-in program.
6644 @item @code{login-pause?} (default: @code{#f})
6645 When set to @code{#t} in conjunction with @var{auto-login}, the user
6646 will have to press a key before the log-in shell is launched.
6648 @item @code{mingetty} (default: @var{mingetty})
6649 The Mingetty package to use.
6654 @cindex name service cache daemon
6656 @deffn {Scheme Procedure} nscd-service [@var{config}] [#:glibc glibc] @
6657 [#:name-services '()]
6658 Return a service that runs libc's name service cache daemon (nscd) with the
6659 given @var{config}---an @code{<nscd-configuration>} object. @xref{Name
6660 Service Switch}, for an example.
6663 @defvr {Scheme Variable} %nscd-default-configuration
6664 This is the default @code{<nscd-configuration>} value (see below) used
6665 by @code{nscd-service}. This uses the caches defined by
6666 @var{%nscd-default-caches}; see below.
6669 @deftp {Data Type} nscd-configuration
6670 This is the type representing the name service cache daemon (nscd)
6675 @item @code{name-services} (default: @code{'()})
6676 List of packages denoting @dfn{name services} that must be visible to
6677 the nscd---e.g., @code{(list @var{nss-mdns})}.
6679 @item @code{glibc} (default: @var{glibc})
6680 Package object denoting the GNU C Library providing the @command{nscd}
6683 @item @code{log-file} (default: @code{"/var/log/nscd.log"})
6684 Name of nscd's log file. This is where debugging output goes when
6685 @code{debug-level} is strictly positive.
6687 @item @code{debug-level} (default: @code{0})
6688 Integer denoting the debugging levels. Higher numbers mean more
6689 debugging output is logged.
6691 @item @code{caches} (default: @var{%nscd-default-caches})
6692 List of @code{<nscd-cache>} objects denoting things to be cached; see
6698 @deftp {Data Type} nscd-cache
6699 Data type representing a cache database of nscd and its parameters.
6703 @item @code{database}
6704 This is a symbol representing the name of the database to be cached.
6705 Valid values are @code{passwd}, @code{group}, @code{hosts}, and
6706 @code{services}, which designate the corresponding NSS database
6707 (@pxref{NSS Basics,,, libc, The GNU C Library Reference Manual}).
6709 @item @code{positive-time-to-live}
6710 @itemx @code{negative-time-to-live} (default: @code{20})
6711 A number representing the number of seconds during which a positive or
6712 negative lookup result remains in cache.
6714 @item @code{check-files?} (default: @code{#t})
6715 Whether to check for updates of the files corresponding to
6718 For instance, when @var{database} is @code{hosts}, setting this flag
6719 instructs nscd to check for updates in @file{/etc/hosts} and to take
6722 @item @code{persistent?} (default: @code{#t})
6723 Whether the cache should be stored persistently on disk.
6725 @item @code{shared?} (default: @code{#t})
6726 Whether the cache should be shared among users.
6728 @item @code{max-database-size} (default: 32@tie{}MiB)
6729 Maximum size in bytes of the database cache.
6731 @c XXX: 'suggested-size' and 'auto-propagate?' seem to be expert
6732 @c settings, so leave them out.
6737 @defvr {Scheme Variable} %nscd-default-caches
6738 List of @code{<nscd-cache>} objects used by default by
6739 @code{nscd-configuration} (see above.)
6741 It enables persistent and aggressive caching of service and host name
6742 lookups. The latter provides better host name lookup performance,
6743 resilience in the face of unreliable name servers, and also better
6744 privacy---often the result of host name lookups is in local cache, so
6745 external name servers do not even need to be queried.
6749 @deffn {Scheme Procedure} syslog-service [#:config-file #f]
6750 Return a service that runs @code{syslogd}. If configuration file name
6751 @var{config-file} is not specified, use some reasonable default
6755 @anchor{guix-configuration-type}
6756 @deftp {Data Type} guix-configuration
6757 This data type represents the configuration of the Guix build daemon.
6758 @xref{Invoking guix-daemon}, for more information.
6761 @item @code{guix} (default: @var{guix})
6762 The Guix package to use.
6764 @item @code{build-group} (default: @code{"guixbuild"})
6765 Name of the group for build user accounts.
6767 @item @code{build-accounts} (default: @code{10})
6768 Number of build user accounts to create.
6770 @item @code{authorize-key?} (default: @code{#t})
6771 Whether to authorize the substitute key for @code{hydra.gnu.org}
6772 (@pxref{Substitutes}).
6774 @item @code{use-substitutes?} (default: @code{#t})
6775 Whether to use substitutes.
6777 @item @code{substitute-urls} (default: @var{%default-substitute-urls})
6778 The list of URLs where to look for substitutes by default.
6780 @item @code{extra-options} (default: @code{'()})
6781 List of extra command-line options for @command{guix-daemon}.
6783 @item @code{lsof} (default: @var{lsof})
6784 @itemx @code{lsh} (default: @var{lsh})
6785 The lsof and lsh packages to use.
6790 @deffn {Scheme Procedure} guix-service @var{config}
6791 Return a service that runs the Guix build daemon according to
6795 @deffn {Scheme Procedure} udev-service [#:udev udev]
6796 Run @var{udev}, which populates the @file{/dev} directory dynamically.
6799 @deffn {Scheme Procedure} console-keymap-service @var{file}
6800 Return a service to load console keymap from @var{file} using
6801 @command{loadkeys} command.
6804 @deffn {Scheme Procedure} gpm-service-type [#:gpm @var{gpm}] @
6806 Run @var{gpm}, the general-purpose mouse daemon, with the given
6807 command-line @var{options}. GPM allows users to use the mouse in the console,
6808 notably to select, copy, and paste text. The default value of @var{options}
6809 uses the @code{ps2} protocol, which works for both USB and PS/2 mice.
6811 This service is not part of @var{%base-services}.
6814 @anchor{guix-publish-service}
6815 @deffn {Scheme Procedure} guix-publish-service [#:guix @var{guix}] @
6816 [#:port 80] [#:host "localhost"]
6817 Return a service that runs @command{guix publish} listening on @var{host}
6818 and @var{port} (@pxref{Invoking guix publish}).
6820 This assumes that @file{/etc/guix} already contains a signing key pair as
6821 created by @command{guix archive --generate-key} (@pxref{Invoking guix
6822 archive}). If that is not the case, the service will fail to start.
6826 @node Networking Services
6827 @subsubsection Networking Services
6829 The @code{(gnu services networking)} module provides services to configure
6830 the network interface.
6832 @cindex DHCP, networking service
6833 @deffn {Scheme Procedure} dhcp-client-service [#:dhcp @var{isc-dhcp}]
6834 Return a service that runs @var{dhcp}, a Dynamic Host Configuration
6835 Protocol (DHCP) client, on all the non-loopback network interfaces.
6838 @deffn {Scheme Procedure} static-networking-service @var{interface} @var{ip} @
6839 [#:gateway #f] [#:name-services @code{'()}]
6840 Return a service that starts @var{interface} with address @var{ip}. If
6841 @var{gateway} is true, it must be a string specifying the default network
6846 @cindex network management
6847 @deffn {Scheme Procedure} wicd-service [#:wicd @var{wicd}]
6848 Return a service that runs @url{https://launchpad.net/wicd,Wicd}, a network
6849 management daemon that aims to simplify wired and wireless networking.
6851 This service adds the @var{wicd} package to the global profile, providing
6852 several commands to interact with the daemon and configure networking:
6853 @command{wicd-client}, a graphical user interface, and the @command{wicd-cli}
6854 and @command{wicd-curses} user interfaces.
6857 @cindex NetworkManager
6858 @deffn {Scheme Procedure} network-manager-service @
6859 [#:network-manager @var{network-manager}]
6860 Return a service that runs NetworkManager, a network connection manager
6861 that attempting to keep active network connectivity when available.
6864 @deffn {Scheme Procedure} ntp-service [#:ntp @var{ntp}] @
6865 [#:name-service @var{%ntp-servers}]
6866 Return a service that runs the daemon from @var{ntp}, the
6867 @uref{http://www.ntp.org, Network Time Protocol package}. The daemon will
6868 keep the system clock synchronized with that of @var{servers}.
6871 @defvr {Scheme Variable} %ntp-servers
6872 List of host names used as the default NTP servers.
6875 @deffn {Scheme Procedure} tor-service [@var{config-file}] [#:tor @var{tor}]
6876 Return a service to run the @uref{https://torproject.org, Tor} anonymous
6879 The daemon runs as the @code{tor} unprivileged user. It is passed
6880 @var{config-file}, a file-like object, with an additional @code{User tor} line
6881 and lines for hidden services added via @code{tor-hidden-service}. Run
6882 @command{man tor} for information about the configuration file.
6885 @cindex hidden service
6886 @deffn {Scheme Procedure} tor-hidden-service @var{name} @var{mapping}
6887 Define a new Tor @dfn{hidden service} called @var{name} and implementing
6888 @var{mapping}. @var{mapping} is a list of port/host tuples, such as:
6891 '((22 "127.0.0.1:22")
6892 (80 "127.0.0.1:8080"))
6895 In this example, port 22 of the hidden service is mapped to local port 22, and
6896 port 80 is mapped to local port 8080.
6898 This creates a @file{/var/lib/tor/hidden-services/@var{name}} directory, where
6899 the @file{hostname} file contains the @code{.onion} host name for the hidden
6902 See @uref{https://www.torproject.org/docs/tor-hidden-service.html.en, the Tor
6903 project's documentation} for more information.
6906 @deffn {Scheme Procedure} bitlbee-service [#:bitlbee bitlbee] @
6907 [#:interface "127.0.0.1"] [#:port 6667] @
6908 [#:extra-settings ""]
6909 Return a service that runs @url{http://bitlbee.org,BitlBee}, a daemon that
6910 acts as a gateway between IRC and chat networks.
6912 The daemon will listen to the interface corresponding to the IP address
6913 specified in @var{interface}, on @var{port}. @code{127.0.0.1} means that only
6914 local clients can connect, whereas @code{0.0.0.0} means that connections can
6915 come from any networking interface.
6917 In addition, @var{extra-settings} specifies a string to append to the
6921 Furthermore, @code{(gnu services ssh)} provides the following service.
6923 @deffn {Scheme Procedure} lsh-service [#:host-key "/etc/lsh/host-key"] @
6924 [#:daemonic? #t] [#:interfaces '()] [#:port-number 22] @
6925 [#:allow-empty-passwords? #f] [#:root-login? #f] @
6926 [#:syslog-output? #t] [#:x11-forwarding? #t] @
6927 [#:tcp/ip-forwarding? #t] [#:password-authentication? #t] @
6928 [#:public-key-authentication? #t] [#:initialize? #t]
6929 Run the @command{lshd} program from @var{lsh} to listen on port @var{port-number}.
6930 @var{host-key} must designate a file containing the host key, and readable
6933 When @var{daemonic?} is true, @command{lshd} will detach from the
6934 controlling terminal and log its output to syslogd, unless one sets
6935 @var{syslog-output?} to false. Obviously, it also makes lsh-service
6936 depend on existence of syslogd service. When @var{pid-file?} is true,
6937 @command{lshd} writes its PID to the file called @var{pid-file}.
6939 When @var{initialize?} is true, automatically create the seed and host key
6940 upon service activation if they do not exist yet. This may take long and
6941 require interaction.
6943 When @var{initialize?} is false, it is up to the user to initialize the
6944 randomness generator (@pxref{lsh-make-seed,,, lsh, LSH Manual}), and to create
6945 a key pair with the private key stored in file @var{host-key} (@pxref{lshd
6946 basics,,, lsh, LSH Manual}).
6948 When @var{interfaces} is empty, lshd listens for connections on all the
6949 network interfaces; otherwise, @var{interfaces} must be a list of host names
6952 @var{allow-empty-passwords?} specifies whether to accept log-ins with empty
6953 passwords, and @var{root-login?} specifies whether to accept log-ins as
6956 The other options should be self-descriptive.
6959 @defvr {Scheme Variable} %facebook-host-aliases
6960 This variable contains a string for use in @file{/etc/hosts}
6961 (@pxref{Host Names,,, libc, The GNU C Library Reference Manual}). Each
6962 line contains a entry that maps a known server name of the Facebook
6963 on-line service---e.g., @code{www.facebook.com}---to the local
6964 host---@code{127.0.0.1} or its IPv6 equivalent, @code{::1}.
6966 This variable is typically used in the @code{hosts-file} field of an
6967 @code{operating-system} declaration (@pxref{operating-system Reference,
6968 @file{/etc/hosts}}):
6971 (use-modules (gnu) (guix))
6974 (host-name "mymachine")
6977 ;; Create a /etc/hosts file with aliases for "localhost"
6978 ;; and "mymachine", as well as for Facebook servers.
6980 (string-append (local-host-aliases host-name)
6981 %facebook-host-aliases))))
6984 This mechanism can prevent programs running locally, such as Web
6985 browsers, from accessing Facebook.
6988 The @code{(gnu services avahi)} provides the following definition.
6990 @deffn {Scheme Procedure} avahi-service [#:avahi @var{avahi}] @
6991 [#:host-name #f] [#:publish? #t] [#:ipv4? #t] @
6992 [#:ipv6? #t] [#:wide-area? #f] @
6993 [#:domains-to-browse '()]
6994 Return a service that runs @command{avahi-daemon}, a system-wide
6995 mDNS/DNS-SD responder that allows for service discovery and
6996 "zero-configuration" host name lookups (see @uref{http://avahi.org/}), and
6997 extends the name service cache daemon (nscd) so that it can resolve
6998 @code{.local} host names using
6999 @uref{http://0pointer.de/lennart/projects/nss-mdns/, nss-mdns}. Additionally,
7000 add the @var{avahi} package to the system profile so that commands such as
7001 @command{avahi-browse} are directly usable.
7003 If @var{host-name} is different from @code{#f}, use that as the host name to
7004 publish for this machine; otherwise, use the machine's actual host name.
7006 When @var{publish?} is true, publishing of host names and services is allowed;
7007 in particular, avahi-daemon will publish the machine's host name and IP
7008 address via mDNS on the local network.
7010 When @var{wide-area?} is true, DNS-SD over unicast DNS is enabled.
7012 Boolean values @var{ipv4?} and @var{ipv6?} determine whether to use IPv4/IPv6
7018 @subsubsection X Window
7020 Support for the X Window graphical display system---specifically
7021 Xorg---is provided by the @code{(gnu services xorg)} module. Note that
7022 there is no @code{xorg-service} procedure. Instead, the X server is
7023 started by the @dfn{login manager}, currently SLiM.
7025 @deffn {Scheme Procedure} slim-service [#:allow-empty-passwords? #f] @
7026 [#:auto-login? #f] [#:default-user ""] [#:startx] @
7027 [#:theme @var{%default-slim-theme}] @
7028 [#:theme-name @var{%default-slim-theme-name}]
7029 Return a service that spawns the SLiM graphical login manager, which in
7030 turn starts the X display server with @var{startx}, a command as returned by
7031 @code{xorg-start-command}.
7035 SLiM automatically looks for session types described by the @file{.desktop}
7036 files in @file{/run/current-system/profile/share/xsessions} and allows users
7037 to choose a session from the log-in screen using @kbd{F1}. Packages such as
7038 @var{xfce}, @var{sawfish}, and @var{ratpoison} provide @file{.desktop} files;
7039 adding them to the system-wide set of packages automatically makes them
7040 available at the log-in screen.
7042 In addition, @file{~/.xsession} files are honored. When available,
7043 @file{~/.xsession} must be an executable that starts a window manager
7044 and/or other X clients.
7046 When @var{allow-empty-passwords?} is true, allow logins with an empty
7047 password. When @var{auto-login?} is true, log in automatically as
7050 If @var{theme} is @code{#f}, the use the default log-in theme; otherwise
7051 @var{theme} must be a gexp denoting the name of a directory containing the
7052 theme to use. In that case, @var{theme-name} specifies the name of the
7056 @defvr {Scheme Variable} %default-theme
7057 @defvrx {Scheme Variable} %default-theme-name
7058 The G-Expression denoting the default SLiM theme and its name.
7061 @deffn {Scheme Procedure} xorg-start-command [#:guile] @
7062 [#:configuration-file #f] [#:xorg-server @var{xorg-server}]
7063 Return a derivation that builds a @var{guile} script to start the X server
7064 from @var{xorg-server}. @var{configuration-file} is the server configuration
7065 file or a derivation that builds it; when omitted, the result of
7066 @code{xorg-configuration-file} is used.
7068 Usually the X server is started by a login manager.
7071 @deffn {Scheme Procedure} xorg-configuration-file @
7072 [#:drivers '()] [#:resolutions '()] [#:extra-config '()]
7073 Return a configuration file for the Xorg server containing search paths for
7074 all the common drivers.
7076 @var{drivers} must be either the empty list, in which case Xorg chooses a
7077 graphics driver automatically, or a list of driver names that will be tried in
7078 this order---e.g., @code{(\"modesetting\" \"vesa\")}.
7080 Likewise, when @var{resolutions} is the empty list, Xorg chooses an
7081 appropriate screen resolution; otherwise, it must be a list of
7082 resolutions---e.g., @code{((1024 768) (640 480))}.
7084 Last, @var{extra-config} is a list of strings or objects appended to the
7085 @code{text-file*} argument list. It is used to pass extra text to be added
7086 verbatim to the configuration file.
7089 @deffn {Scheme Procedure} screen-locker-service @var{package} [@var{name}]
7090 Add @var{package}, a package for a screen-locker or screen-saver whose
7091 command is @var{program}, to the set of setuid programs and add a PAM entry
7092 for it. For example:
7095 (screen-locker-service xlockmore "xlock")
7098 makes the good ol' XlockMore usable.
7102 @node Desktop Services
7103 @subsubsection Desktop Services
7105 The @code{(gnu services desktop)} module provides services that are
7106 usually useful in the context of a ``desktop'' setup---that is, on a
7107 machine running a graphical display server, possibly with graphical user
7110 To simplify things, the module defines a variable containing the set of
7111 services that users typically expect on a machine with a graphical
7112 environment and networking:
7114 @defvr {Scheme Variable} %desktop-services
7115 This is a list of services that builds upon @var{%base-services} and
7116 adds or adjust services for a typical ``desktop'' setup.
7118 In particular, it adds a graphical login manager (@pxref{X Window,
7119 @code{slim-service}}), screen lockers,
7120 a network management tool (@pxref{Networking
7121 Services, @code{wicd-service}}), energy and color management services,
7122 the @code{elogind} login and seat manager, the Polkit privilege service,
7123 the GeoClue location service, an NTP client (@pxref{Networking
7124 Services}), the Avahi daemon, and has the name service switch service
7125 configured to be able to use @code{nss-mdns} (@pxref{Name Service
7129 The @var{%desktop-services} variable can be used as the @code{services}
7130 field of an @code{operating-system} declaration (@pxref{operating-system
7131 Reference, @code{services}}).
7133 The actual service definitions provided by @code{(gnu services dbus)}
7134 and @code{(gnu services desktop)} are described below.
7136 @deffn {Scheme Procedure} dbus-service [#:dbus @var{dbus}] [#:services '()]
7137 Return a service that runs the ``system bus'', using @var{dbus}, with
7138 support for @var{services}.
7140 @uref{http://dbus.freedesktop.org/, D-Bus} is an inter-process communication
7141 facility. Its system bus is used to allow system services to communicate
7142 and be notified of system-wide events.
7144 @var{services} must be a list of packages that provide an
7145 @file{etc/dbus-1/system.d} directory containing additional D-Bus configuration
7146 and policy files. For example, to allow avahi-daemon to use the system bus,
7147 @var{services} must be equal to @code{(list avahi)}.
7150 @deffn {Scheme Procedure} elogind-service [#:config @var{config}]
7151 Return a service that runs the @code{elogind} login and
7152 seat management daemon. @uref{https://github.com/andywingo/elogind,
7153 Elogind} exposes a D-Bus interface that can be used to know which users
7154 are logged in, know what kind of sessions they have open, suspend the
7155 system, inhibit system suspend, reboot the system, and other tasks.
7157 Elogind handles most system-level power events for a computer, for
7158 example suspending the system when a lid is closed, or shutting it down
7159 when the power button is pressed.
7161 The @var{config} keyword argument specifies the configuration for
7162 elogind, and should be the result of a @code{(elogind-configuration
7163 (@var{parameter} @var{value})...)} invocation. Available parameters and
7164 their default values are:
7167 @item kill-user-processes?
7169 @item kill-only-users
7171 @item kill-exclude-users
7173 @item inhibit-delay-max-seconds
7175 @item handle-power-key
7177 @item handle-suspend-key
7179 @item handle-hibernate-key
7181 @item handle-lid-switch
7183 @item handle-lid-switch-docked
7185 @item power-key-ignore-inhibited?
7187 @item suspend-key-ignore-inhibited?
7189 @item hibernate-key-ignore-inhibited?
7191 @item lid-switch-ignore-inhibited?
7193 @item holdoff-timeout-seconds
7197 @item idle-action-seconds
7199 @item runtime-directory-size-percent
7201 @item runtime-directory-size
7206 @code{("mem" "standby" "freeze")}
7209 @item hibernate-state
7211 @item hibernate-mode
7212 @code{("platform" "shutdown")}
7213 @item hybrid-sleep-state
7215 @item hybrid-sleep-mode
7216 @code{("suspend" "platform" "shutdown")}
7220 @deffn {Scheme Procedure} polkit-service @
7221 [#:polkit @var{polkit}]
7222 Return a service that runs the
7223 @uref{http://www.freedesktop.org/wiki/Software/polkit/, Polkit privilege
7224 management service}, which allows system administrators to grant access to
7225 privileged operations in a structured way. By querying the Polkit service, a
7226 privileged system component can know when it should grant additional
7227 capabilities to ordinary users. For example, an ordinary user can be granted
7228 the capability to suspend the system if the user is logged in locally.
7231 @deffn {Scheme Procedure} upower-service [#:upower @var{upower}] @
7232 [#:watts-up-pro? #f] @
7233 [#:poll-batteries? #t] @
7234 [#:ignore-lid? #f] @
7235 [#:use-percentage-for-policy? #f] @
7236 [#:percentage-low 10] @
7237 [#:percentage-critical 3] @
7238 [#:percentage-action 2] @
7240 [#:time-critical 300] @
7241 [#:time-action 120] @
7242 [#:critical-power-action 'hybrid-sleep]
7243 Return a service that runs @uref{http://upower.freedesktop.org/,
7244 @command{upowerd}}, a system-wide monitor for power consumption and battery
7245 levels, with the given configuration settings. It implements the
7246 @code{org.freedesktop.UPower} D-Bus interface, and is notably used by
7250 @deffn {Scheme Procedure} udisks-service [#:udisks @var{udisks}]
7251 Return a service for @uref{http://udisks.freedesktop.org/docs/latest/,
7252 UDisks}, a @dfn{disk management} daemon that provides user interfaces with
7253 notifications and ways to mount/unmount disks. Programs that talk to UDisks
7254 include the @command{udisksctl} command, part of UDisks, and GNOME Disks.
7257 @deffn {Scheme Procedure} colord-service [#:colord @var{colord}]
7258 Return a service that runs @command{colord}, a system service with a D-Bus
7259 interface to manage the color profiles of input and output devices such as
7260 screens and scanners. It is notably used by the GNOME Color Manager graphical
7261 tool. See @uref{http://www.freedesktop.org/software/colord/, the colord web
7262 site} for more information.
7265 @deffn {Scheme Procedure} geoclue-application name [#:allowed? #t] [#:system? #f] [#:users '()]
7266 Return an configuration allowing an application to access GeoClue
7267 location data. @var{name} is the Desktop ID of the application, without
7268 the @code{.desktop} part. If @var{allowed?} is true, the application
7269 will have access to location information by default. The boolean
7270 @var{system?} value indicates that an application is a system component
7271 or not. Finally @var{users} is a list of UIDs of all users for which
7272 this application is allowed location info access. An empty users list
7273 means that all users are allowed.
7276 @defvr {Scheme Variable} %standard-geoclue-applications
7277 The standard list of well-known GeoClue application configurations,
7278 granting authority to GNOME's date-and-time utility to ask for the
7279 current location in order to set the time zone, and allowing the Firefox
7280 (IceCat) and Epiphany web browsers to request location information.
7281 Firefox and Epiphany both query the user before allowing a web page to
7282 know the user's location.
7285 @deffn {Scheme Procedure} geoclue-service [#:colord @var{colord}] @
7287 [#:wifi-geolocation-url "https://location.services.mozilla.com/v1/geolocate?key=geoclue"] @
7289 [#:wifi-submission-url "https://location.services.mozilla.com/v1/submit?key=geoclue"] @
7290 [#:submission-nick "geoclue"] @
7291 [#:applications %standard-geoclue-applications]
7292 Return a service that runs the GeoClue location service. This service
7293 provides a D-Bus interface to allow applications to request access to a
7294 user's physical location, and optionally to add information to online
7295 location databases. See
7296 @uref{https://wiki.freedesktop.org/www/Software/GeoClue/, the GeoClue
7297 web site} for more information.
7300 @node Database Services
7301 @subsubsection Database Services
7303 The @code{(gnu services databases)} module provides the following service.
7305 @deffn {Scheme Procedure} postgresql-service [#:postgresql postgresql] @
7306 [#:config-file] [#:data-directory ``/var/lib/postgresql/data'']
7307 Return a service that runs @var{postgresql}, the PostgreSQL database
7310 The PostgreSQL daemon loads its runtime configuration from
7311 @var{config-file} and stores the database cluster in
7312 @var{data-directory}.
7316 @subsubsection Mail Services
7318 The @code{(gnu services mail)} module provides Guix service definitions
7319 for mail services. Currently the only implemented service is Dovecot,
7320 an IMAP, POP3, and LMTP server.
7322 Guix does not yet have a mail transfer agent (MTA), although for some
7323 lightweight purposes the @code{esmtp} relay-only MTA may suffice. Help
7324 is needed to properly integrate a full MTA, such as Postfix. Patches
7327 To add an IMAP/POP3 server to a GuixSD system, add a
7328 @code{dovecot-service} to the operating system definition:
7330 @deffn {Scheme Procedure} dovecot-service [#:config (dovecot-configuration)]
7331 Return a service that runs the Dovecot IMAP/POP3/LMTP mail server.
7334 By default, Dovecot doesn't need much configuration; the default
7335 configuration object created by @code{(dovecot-configuration)} will
7336 suffice if your mail is delivered to @code{~/Maildir}. A self-signed
7337 certificate will be generated for TLS-protected connections, though
7338 Dovecot will also listen on cleartext ports by default. There are a
7339 number of options though which mail administrators might need to change,
7340 and as is the case with other services, Guix allows the system
7341 administrator to specify these parameters via a uniform Scheme interface.
7343 For example, to specify that mail is located at @code{maildir~/.mail},
7344 one would instantiate the Dovecot service like this:
7347 (dovecot-service #:config
7348 (dovecot-configuration
7349 (mail-location "maildir:~/.mail")))
7352 The available configuration parameters follow. Each parameter
7353 definition is preceded by its type; for example, @samp{string-list foo}
7354 indicates that the @code{foo} parameter should be specified as a list of
7355 strings. There is also a way to specify the configuration as a string,
7356 if you have an old @code{dovecot.conf} file that you want to port over
7357 from some other system; see the end for more details.
7359 @c The following documentation was initially generated by
7360 @c (generate-documentation) in (gnu services mail). Manually maintained
7361 @c documentation is better, so we shouldn't hesitate to edit below as
7362 @c needed. However if the change you want to make to this documentation
7363 @c can be done in an automated way, it's probably easier to change
7364 @c (generate-documentation) than to make it below and have to deal with
7365 @c the churn as dovecot updates.
7367 Available @code{dovecot-configuration} fields are:
7369 @deftypevr {@code{dovecot-configuration} parameter} package dovecot
7370 The dovecot package.
7373 @deftypevr {@code{dovecot-configuration} parameter} comma-separated-string-list listen
7374 A list of IPs or hosts where to listen in for connections. @samp{*}
7375 listens in all IPv4 interfaces, @samp{::} listens in all IPv6
7376 interfaces. If you want to specify non-default ports or anything more
7377 complex, customize the address and port fields of the
7378 @samp{inet-listener} of the specific services you are interested in.
7381 @deftypevr {@code{dovecot-configuration} parameter} protocol-configuration-list protocols
7382 List of protocols we want to serve. Available protocols include
7383 @samp{imap}, @samp{pop3}, and @samp{lmtp}.
7385 Available @code{protocol-configuration} fields are:
7387 @deftypevr {@code{protocol-configuration} parameter} string name
7388 The name of the protocol.
7391 @deftypevr {@code{protocol-configuration} parameter} string auth-socket-path
7392 UNIX socket path to master authentication server to find users.
7393 This is used by imap (for shared users) and lda.
7394 Defaults to @samp{"/var/run/dovecot/auth-userdb"}.
7397 @deftypevr {@code{protocol-configuration} parameter} space-separated-string-list mail-plugins
7398 Space separated list of plugins to load.
7401 @deftypevr {@code{protocol-configuration} parameter} non-negative-integer mail-max-userip-connections
7402 Maximum number of IMAP connections allowed for a user from each IP
7403 address. NOTE: The username is compared case-sensitively.
7404 Defaults to @samp{10}.
7409 @deftypevr {@code{dovecot-configuration} parameter} service-configuration-list services
7410 List of services to enable. Available services include @samp{imap},
7411 @samp{imap-login}, @samp{pop3}, @samp{pop3-login}, @samp{auth}, and
7414 Available @code{service-configuration} fields are:
7416 @deftypevr {@code{service-configuration} parameter} string kind
7417 The service kind. Valid values include @code{director},
7418 @code{imap-login}, @code{pop3-login}, @code{lmtp}, @code{imap},
7419 @code{pop3}, @code{auth}, @code{auth-worker}, @code{dict},
7420 @code{tcpwrap}, @code{quota-warning}, or anything else.
7423 @deftypevr {@code{service-configuration} parameter} listener-configuration-list listeners
7424 Listeners for the service. A listener is either an
7425 @code{unix-listener-configuration}, a @code{fifo-listener-configuration}, or
7426 an @code{inet-listener-configuration}.
7427 Defaults to @samp{()}.
7429 Available @code{unix-listener-configuration} fields are:
7431 @deftypevr {@code{unix-listener-configuration} parameter} file-name path
7432 The file name on which to listen.
7435 @deftypevr {@code{unix-listener-configuration} parameter} string mode
7436 The access mode for the socket.
7437 Defaults to @samp{"0600"}.
7440 @deftypevr {@code{unix-listener-configuration} parameter} string user
7441 The user to own the socket.
7442 Defaults to @samp{""}.
7445 @deftypevr {@code{unix-listener-configuration} parameter} string group
7446 The group to own the socket.
7447 Defaults to @samp{""}.
7451 Available @code{fifo-listener-configuration} fields are:
7453 @deftypevr {@code{fifo-listener-configuration} parameter} file-name path
7454 The file name on which to listen.
7457 @deftypevr {@code{fifo-listener-configuration} parameter} string mode
7458 The access mode for the socket.
7459 Defaults to @samp{"0600"}.
7462 @deftypevr {@code{fifo-listener-configuration} parameter} string user
7463 The user to own the socket.
7464 Defaults to @samp{""}.
7467 @deftypevr {@code{fifo-listener-configuration} parameter} string group
7468 The group to own the socket.
7469 Defaults to @samp{""}.
7473 Available @code{inet-listener-configuration} fields are:
7475 @deftypevr {@code{inet-listener-configuration} parameter} string protocol
7476 The protocol to listen for.
7479 @deftypevr {@code{inet-listener-configuration} parameter} string address
7480 The address on which to listen, or empty for all addresses.
7481 Defaults to @samp{""}.
7484 @deftypevr {@code{inet-listener-configuration} parameter} non-negative-integer port
7485 The port on which to listen.
7488 @deftypevr {@code{inet-listener-configuration} parameter} boolean ssl?
7489 Whether to use SSL for this service; @samp{yes}, @samp{no}, or
7491 Defaults to @samp{#t}.
7496 @deftypevr {@code{service-configuration} parameter} non-negative-integer service-count
7497 Number of connections to handle before starting a new process.
7498 Typically the only useful values are 0 (unlimited) or 1. 1 is more
7499 secure, but 0 is faster. <doc/wiki/LoginProcess.txt>.
7500 Defaults to @samp{1}.
7503 @deftypevr {@code{service-configuration} parameter} non-negative-integer process-min-avail
7504 Number of processes to always keep waiting for more connections.
7505 Defaults to @samp{0}.
7508 @deftypevr {@code{service-configuration} parameter} non-negative-integer vsz-limit
7509 If you set @samp{service-count 0}, you probably need to grow
7511 Defaults to @samp{256000000}.
7516 @deftypevr {@code{dovecot-configuration} parameter} dict-configuration dict
7517 Dict configuration, as created by the @code{dict-configuration}
7520 Available @code{dict-configuration} fields are:
7522 @deftypevr {@code{dict-configuration} parameter} free-form-fields entries
7523 A list of key-value pairs that this dict should hold.
7524 Defaults to @samp{()}.
7529 @deftypevr {@code{dovecot-configuration} parameter} passdb-configuration-list passdbs
7530 List of passdb configurations, each one created by the
7531 @code{passdb-configuration} constructor.
7533 Available @code{passdb-configuration} fields are:
7535 @deftypevr {@code{passdb-configuration} parameter} string driver
7536 The driver that the passdb should use. Valid values include
7537 @samp{pam}, @samp{passwd}, @samp{shadow}, @samp{bsdauth}, and
7539 Defaults to @samp{"pam"}.
7542 @deftypevr {@code{passdb-configuration} parameter} free-form-args args
7543 A list of key-value args to the passdb driver.
7544 Defaults to @samp{()}.
7549 @deftypevr {@code{dovecot-configuration} parameter} userdb-configuration-list userdbs
7550 List of userdb configurations, each one created by the
7551 @code{userdb-configuration} constructor.
7553 Available @code{userdb-configuration} fields are:
7555 @deftypevr {@code{userdb-configuration} parameter} string driver
7556 The driver that the userdb should use. Valid values include
7557 @samp{passwd} and @samp{static}.
7558 Defaults to @samp{"passwd"}.
7561 @deftypevr {@code{userdb-configuration} parameter} free-form-args args
7562 A list of key-value args to the userdb driver.
7563 Defaults to @samp{()}.
7566 @deftypevr {@code{userdb-configuration} parameter} free-form-args override-fields
7567 Override fields from passwd.
7568 Defaults to @samp{()}.
7573 @deftypevr {@code{dovecot-configuration} parameter} plugin-configuration plugin-configuration
7574 Plug-in configuration, created by the @code{plugin-configuration}
7578 @deftypevr {@code{dovecot-configuration} parameter} list-of-namespace-configuration namespaces
7579 List of namespaces. Each item in the list is created by the
7580 @code{namespace-configuration} constructor.
7582 Available @code{namespace-configuration} fields are:
7584 @deftypevr {@code{namespace-configuration} parameter} string name
7585 Name for this namespace.
7588 @deftypevr {@code{namespace-configuration} parameter} string type
7589 Namespace type: @samp{private}, @samp{shared} or @samp{public}.
7590 Defaults to @samp{"private"}.
7593 @deftypevr {@code{namespace-configuration} parameter} string separator
7594 Hierarchy separator to use. You should use the same separator for
7595 all namespaces or some clients get confused. @samp{/} is usually a good
7596 one. The default however depends on the underlying mail storage
7598 Defaults to @samp{""}.
7601 @deftypevr {@code{namespace-configuration} parameter} string prefix
7602 Prefix required to access this namespace. This needs to be
7603 different for all namespaces. For example @samp{Public/}.
7604 Defaults to @samp{""}.
7607 @deftypevr {@code{namespace-configuration} parameter} string location
7608 Physical location of the mailbox. This is in same format as
7609 mail_location, which is also the default for it.
7610 Defaults to @samp{""}.
7613 @deftypevr {@code{namespace-configuration} parameter} boolean inbox?
7614 There can be only one INBOX, and this setting defines which
7616 Defaults to @samp{#f}.
7619 @deftypevr {@code{namespace-configuration} parameter} boolean hidden?
7620 If namespace is hidden, it's not advertised to clients via NAMESPACE
7621 extension. You'll most likely also want to set @samp{list? #f}. This is mostly
7622 useful when converting from another server with different namespaces
7623 which you want to deprecate but still keep working. For example you can
7624 create hidden namespaces with prefixes @samp{~/mail/}, @samp{~%u/mail/}
7626 Defaults to @samp{#f}.
7629 @deftypevr {@code{namespace-configuration} parameter} boolean list?
7630 Show the mailboxes under this namespace with LIST command. This
7631 makes the namespace visible for clients that don't support NAMESPACE
7632 extension. The special @code{children} value lists child mailboxes, but
7633 hides the namespace prefix.
7634 Defaults to @samp{#t}.
7637 @deftypevr {@code{namespace-configuration} parameter} boolean subscriptions?
7638 Namespace handles its own subscriptions. If set to @code{#f}, the
7639 parent namespace handles them. The empty prefix should always have this
7641 Defaults to @samp{#t}.
7644 @deftypevr {@code{namespace-configuration} parameter} mailbox-configuration-list mailboxes
7645 List of predefined mailboxes in this namespace.
7646 Defaults to @samp{()}.
7648 Available @code{mailbox-configuration} fields are:
7650 @deftypevr {@code{mailbox-configuration} parameter} string name
7651 Name for this mailbox.
7654 @deftypevr {@code{mailbox-configuration} parameter} string auto
7655 @samp{create} will automatically create this mailbox.
7656 @samp{subscribe} will both create and subscribe to the mailbox.
7657 Defaults to @samp{"no"}.
7660 @deftypevr {@code{mailbox-configuration} parameter} space-separated-string-list special-use
7661 List of IMAP @code{SPECIAL-USE} attributes as specified by RFC 6154.
7662 Valid values are @code{\All}, @code{\Archive}, @code{\Drafts},
7663 @code{\Flagged}, @code{\Junk}, @code{\Sent}, and @code{\Trash}.
7664 Defaults to @samp{()}.
7671 @deftypevr {@code{dovecot-configuration} parameter} file-name base-dir
7672 Base directory where to store runtime data.
7673 Defaults to @samp{"/var/run/dovecot/"}.
7676 @deftypevr {@code{dovecot-configuration} parameter} string login-greeting
7677 Greeting message for clients.
7678 Defaults to @samp{"Dovecot ready."}.
7681 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-trusted-networks
7682 List of trusted network ranges. Connections from these IPs are
7683 allowed to override their IP addresses and ports (for logging and for
7684 authentication checks). @samp{disable-plaintext-auth} is also ignored
7685 for these networks. Typically you'd specify your IMAP proxy servers
7687 Defaults to @samp{()}.
7690 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-access-sockets
7691 List of login access check sockets (e.g. tcpwrap).
7692 Defaults to @samp{()}.
7695 @deftypevr {@code{dovecot-configuration} parameter} boolean verbose-proctitle?
7696 Show more verbose process titles (in ps). Currently shows user name
7697 and IP address. Useful for seeing who are actually using the IMAP
7698 processes (e.g. shared mailboxes or if same uid is used for multiple
7700 Defaults to @samp{#f}.
7703 @deftypevr {@code{dovecot-configuration} parameter} boolean shutdown-clients?
7704 Should all processes be killed when Dovecot master process shuts down.
7705 Setting this to @code{#f} means that Dovecot can be upgraded without
7706 forcing existing client connections to close (although that could also
7707 be a problem if the upgrade is e.g. because of a security fix).
7708 Defaults to @samp{#t}.
7711 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer doveadm-worker-count
7712 If non-zero, run mail commands via this many connections to doveadm
7713 server, instead of running them directly in the same process.
7714 Defaults to @samp{0}.
7717 @deftypevr {@code{dovecot-configuration} parameter} string doveadm-socket-path
7718 UNIX socket or host:port used for connecting to doveadm server.
7719 Defaults to @samp{"doveadm-server"}.
7722 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list import-environment
7723 List of environment variables that are preserved on Dovecot startup
7724 and passed down to all of its child processes. You can also give
7725 key=value pairs to always set specific settings.
7728 @deftypevr {@code{dovecot-configuration} parameter} boolean disable-plaintext-auth?
7729 Disable LOGIN command and all other plaintext authentications unless
7730 SSL/TLS is used (LOGINDISABLED capability). Note that if the remote IP
7731 matches the local IP (i.e. you're connecting from the same computer),
7732 the connection is considered secure and plaintext authentication is
7733 allowed. See also ssl=required setting.
7734 Defaults to @samp{#t}.
7737 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer auth-cache-size
7738 Authentication cache size (e.g. @samp{#e10e6}). 0 means it's disabled.
7739 Note that bsdauth, PAM and vpopmail require @samp{cache-key} to be set
7740 for caching to be used.
7741 Defaults to @samp{0}.
7744 @deftypevr {@code{dovecot-configuration} parameter} string auth-cache-ttl
7745 Time to live for cached data. After TTL expires the cached record
7746 is no longer used, *except* if the main database lookup returns internal
7747 failure. We also try to handle password changes automatically: If
7748 user's previous authentication was successful, but this one wasn't, the
7749 cache isn't used. For now this works only with plaintext
7751 Defaults to @samp{"1 hour"}.
7754 @deftypevr {@code{dovecot-configuration} parameter} string auth-cache-negative-ttl
7755 TTL for negative hits (user not found, password mismatch).
7756 0 disables caching them completely.
7757 Defaults to @samp{"1 hour"}.
7760 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list auth-realms
7761 List of realms for SASL authentication mechanisms that need them.
7762 You can leave it empty if you don't want to support multiple realms.
7763 Many clients simply use the first one listed here, so keep the default
7765 Defaults to @samp{()}.
7768 @deftypevr {@code{dovecot-configuration} parameter} string auth-default-realm
7769 Default realm/domain to use if none was specified. This is used for
7770 both SASL realms and appending @@domain to username in plaintext
7772 Defaults to @samp{""}.
7775 @deftypevr {@code{dovecot-configuration} parameter} string auth-username-chars
7776 List of allowed characters in username. If the user-given username
7777 contains a character not listed in here, the login automatically fails.
7778 This is just an extra check to make sure user can't exploit any
7779 potential quote escaping vulnerabilities with SQL/LDAP databases. If
7780 you want to allow all characters, set this value to empty.
7781 Defaults to @samp{"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890.-_@@"}.
7784 @deftypevr {@code{dovecot-configuration} parameter} string auth-username-translation
7785 Username character translations before it's looked up from
7786 databases. The value contains series of from -> to characters. For
7787 example @samp{#@@/@@} means that @samp{#} and @samp{/} characters are
7788 translated to @samp{@@}.
7789 Defaults to @samp{""}.
7792 @deftypevr {@code{dovecot-configuration} parameter} string auth-username-format
7793 Username formatting before it's looked up from databases. You can
7794 use the standard variables here, e.g. %Lu would lowercase the username,
7795 %n would drop away the domain if it was given, or @samp{%n-AT-%d} would
7796 change the @samp{@@} into @samp{-AT-}. This translation is done after
7797 @samp{auth-username-translation} changes.
7798 Defaults to @samp{"%Lu"}.
7801 @deftypevr {@code{dovecot-configuration} parameter} string auth-master-user-separator
7802 If you want to allow master users to log in by specifying the master
7803 username within the normal username string (i.e. not using SASL
7804 mechanism's support for it), you can specify the separator character
7805 here. The format is then <username><separator><master username>.
7806 UW-IMAP uses @samp{*} as the separator, so that could be a good
7808 Defaults to @samp{""}.
7811 @deftypevr {@code{dovecot-configuration} parameter} string auth-anonymous-username
7812 Username to use for users logging in with ANONYMOUS SASL
7814 Defaults to @samp{"anonymous"}.
7817 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer auth-worker-max-count
7818 Maximum number of dovecot-auth worker processes. They're used to
7819 execute blocking passdb and userdb queries (e.g. MySQL and PAM).
7820 They're automatically created and destroyed as needed.
7821 Defaults to @samp{30}.
7824 @deftypevr {@code{dovecot-configuration} parameter} string auth-gssapi-hostname
7825 Host name to use in GSSAPI principal names. The default is to use
7826 the name returned by gethostname(). Use @samp{$ALL} (with quotes) to
7827 allow all keytab entries.
7828 Defaults to @samp{""}.
7831 @deftypevr {@code{dovecot-configuration} parameter} string auth-krb5-keytab
7832 Kerberos keytab to use for the GSSAPI mechanism. Will use the
7833 system default (usually /etc/krb5.keytab) if not specified. You may
7834 need to change the auth service to run as root to be able to read this
7836 Defaults to @samp{""}.
7839 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-use-winbind?
7840 Do NTLM and GSS-SPNEGO authentication using Samba's winbind daemon
7841 and @samp{ntlm-auth} helper.
7842 <doc/wiki/Authentication/Mechanisms/Winbind.txt>.
7843 Defaults to @samp{#f}.
7846 @deftypevr {@code{dovecot-configuration} parameter} file-name auth-winbind-helper-path
7847 Path for Samba's @samp{ntlm-auth} helper binary.
7848 Defaults to @samp{"/usr/bin/ntlm_auth"}.
7851 @deftypevr {@code{dovecot-configuration} parameter} string auth-failure-delay
7852 Time to delay before replying to failed authentications.
7853 Defaults to @samp{"2 secs"}.
7856 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-ssl-require-client-cert?
7857 Require a valid SSL client certificate or the authentication
7859 Defaults to @samp{#f}.
7862 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-ssl-username-from-cert?
7863 Take the username from client's SSL certificate, using
7864 @code{X509_NAME_get_text_by_NID()} which returns the subject's DN's
7866 Defaults to @samp{#f}.
7869 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list auth-mechanisms
7870 List of wanted authentication mechanisms. Supported mechanisms are:
7871 @samp{plain}, @samp{login}, @samp{digest-md5}, @samp{cram-md5},
7872 @samp{ntlm}, @samp{rpa}, @samp{apop}, @samp{anonymous}, @samp{gssapi},
7873 @samp{otp}, @samp{skey}, and @samp{gss-spnego}. NOTE: See also
7874 @samp{disable-plaintext-auth} setting.
7877 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list director-servers
7878 List of IPs or hostnames to all director servers, including ourself.
7879 Ports can be specified as ip:port. The default port is the same as what
7880 director service's @samp{inet-listener} is using.
7881 Defaults to @samp{()}.
7884 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list director-mail-servers
7885 List of IPs or hostnames to all backend mail servers. Ranges are
7886 allowed too, like 10.0.0.10-10.0.0.30.
7887 Defaults to @samp{()}.
7890 @deftypevr {@code{dovecot-configuration} parameter} string director-user-expire
7891 How long to redirect users to a specific server after it no longer
7892 has any connections.
7893 Defaults to @samp{"15 min"}.
7896 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer director-doveadm-port
7897 TCP/IP port that accepts doveadm connections (instead of director
7898 connections) If you enable this, you'll also need to add
7899 @samp{inet-listener} for the port.
7900 Defaults to @samp{0}.
7903 @deftypevr {@code{dovecot-configuration} parameter} string director-username-hash
7904 How the username is translated before being hashed. Useful values
7905 include %Ln if user can log in with or without @@domain, %Ld if mailboxes
7906 are shared within domain.
7907 Defaults to @samp{"%Lu"}.
7910 @deftypevr {@code{dovecot-configuration} parameter} string log-path
7911 Log file to use for error messages. @samp{syslog} logs to syslog,
7912 @samp{/dev/stderr} logs to stderr.
7913 Defaults to @samp{"syslog"}.
7916 @deftypevr {@code{dovecot-configuration} parameter} string info-log-path
7917 Log file to use for informational messages. Defaults to
7919 Defaults to @samp{""}.
7922 @deftypevr {@code{dovecot-configuration} parameter} string debug-log-path
7923 Log file to use for debug messages. Defaults to
7924 @samp{info-log-path}.
7925 Defaults to @samp{""}.
7928 @deftypevr {@code{dovecot-configuration} parameter} string syslog-facility
7929 Syslog facility to use if you're logging to syslog. Usually if you
7930 don't want to use @samp{mail}, you'll use local0..local7. Also other
7931 standard facilities are supported.
7932 Defaults to @samp{"mail"}.
7935 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-verbose?
7936 Log unsuccessful authentication attempts and the reasons why they
7938 Defaults to @samp{#f}.
7941 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-verbose-passwords?
7942 In case of password mismatches, log the attempted password. Valid
7943 values are no, plain and sha1. sha1 can be useful for detecting brute
7944 force password attempts vs. user simply trying the same password over
7945 and over again. You can also truncate the value to n chars by appending
7947 Defaults to @samp{#f}.
7950 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-debug?
7951 Even more verbose logging for debugging purposes. Shows for example
7953 Defaults to @samp{#f}.
7956 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-debug-passwords?
7957 In case of password mismatches, log the passwords and used scheme so
7958 the problem can be debugged. Enabling this also enables
7960 Defaults to @samp{#f}.
7963 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-debug?
7964 Enable mail process debugging. This can help you figure out why
7965 Dovecot isn't finding your mails.
7966 Defaults to @samp{#f}.
7969 @deftypevr {@code{dovecot-configuration} parameter} boolean verbose-ssl?
7970 Show protocol level SSL errors.
7971 Defaults to @samp{#f}.
7974 @deftypevr {@code{dovecot-configuration} parameter} string log-timestamp
7975 Prefix for each line written to log file. % codes are in
7977 Defaults to @samp{"\"%b %d %H:%M:%S \""}.
7980 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-log-format-elements
7981 List of elements we want to log. The elements which have a
7982 non-empty variable value are joined together to form a comma-separated
7986 @deftypevr {@code{dovecot-configuration} parameter} string login-log-format
7987 Login log format. %s contains @samp{login-log-format-elements}
7988 string, %$ contains the data we want to log.
7989 Defaults to @samp{"%$: %s"}.
7992 @deftypevr {@code{dovecot-configuration} parameter} string mail-log-prefix
7993 Log prefix for mail processes. See doc/wiki/Variables.txt for list
7994 of possible variables you can use.
7995 Defaults to @samp{"\"%s(%u): \""}.
7998 @deftypevr {@code{dovecot-configuration} parameter} string deliver-log-format
7999 Format to use for logging mail deliveries. You can use variables:
8002 Delivery status message (e.g. @samp{saved to INBOX})
8014 Defaults to @samp{"msgid=%m: %$"}.
8017 @deftypevr {@code{dovecot-configuration} parameter} string mail-location
8018 Location for users' mailboxes. The default is empty, which means
8019 that Dovecot tries to find the mailboxes automatically. This won't work
8020 if the user doesn't yet have any mail, so you should explicitly tell
8021 Dovecot the full location.
8023 If you're using mbox, giving a path to the INBOX
8024 file (e.g. /var/mail/%u) isn't enough. You'll also need to tell Dovecot
8025 where the other mailboxes are kept. This is called the "root mail
8026 directory", and it must be the first path given in the
8027 @samp{mail-location} setting.
8029 There are a few special variables you can use, eg.:
8035 user part in user@@domain, same as %u if there's no domain
8037 domain part in user@@domain, empty if there's no domain
8042 See doc/wiki/Variables.txt for full list. Some examples:
8044 @item maildir:~/Maildir
8045 @item mbox:~/mail:INBOX=/var/mail/%u
8046 @item mbox:/var/mail/%d/%1n/%n:INDEX=/var/indexes/%d/%1n/%
8048 Defaults to @samp{""}.
8051 @deftypevr {@code{dovecot-configuration} parameter} string mail-uid
8052 System user and group used to access mails. If you use multiple,
8053 userdb can override these by returning uid or gid fields. You can use
8054 either numbers or names. <doc/wiki/UserIds.txt>.
8055 Defaults to @samp{""}.
8058 @deftypevr {@code{dovecot-configuration} parameter} string mail-gid
8060 Defaults to @samp{""}.
8063 @deftypevr {@code{dovecot-configuration} parameter} string mail-privileged-group
8064 Group to enable temporarily for privileged operations. Currently
8065 this is used only with INBOX when either its initial creation or
8066 dotlocking fails. Typically this is set to "mail" to give access to
8068 Defaults to @samp{""}.
8071 @deftypevr {@code{dovecot-configuration} parameter} string mail-access-groups
8072 Grant access to these supplementary groups for mail processes.
8073 Typically these are used to set up access to shared mailboxes. Note
8074 that it may be dangerous to set these if users can create
8075 symlinks (e.g. if "mail" group is set here, ln -s /var/mail ~/mail/var
8076 could allow a user to delete others' mailboxes, or ln -s
8077 /secret/shared/box ~/mail/mybox would allow reading it).
8078 Defaults to @samp{""}.
8081 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-full-filesystem-access?
8082 Allow full filesystem access to clients. There's no access checks
8083 other than what the operating system does for the active UID/GID. It
8084 works with both maildir and mboxes, allowing you to prefix mailboxes
8085 names with e.g. /path/ or ~user/.
8086 Defaults to @samp{#f}.
8089 @deftypevr {@code{dovecot-configuration} parameter} boolean mmap-disable?
8090 Don't use mmap() at all. This is required if you store indexes to
8091 shared filesystems (NFS or clustered filesystem).
8092 Defaults to @samp{#f}.
8095 @deftypevr {@code{dovecot-configuration} parameter} boolean dotlock-use-excl?
8096 Rely on @samp{O_EXCL} to work when creating dotlock files. NFS
8097 supports @samp{O_EXCL} since version 3, so this should be safe to use
8098 nowadays by default.
8099 Defaults to @samp{#t}.
8102 @deftypevr {@code{dovecot-configuration} parameter} string mail-fsync
8103 When to use fsync() or fdatasync() calls:
8106 Whenever necessary to avoid losing important data
8108 Useful with e.g. NFS when write()s are delayed
8110 Never use it (best performance, but crashes can lose data).
8112 Defaults to @samp{"optimized"}.
8115 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-nfs-storage?
8116 Mail storage exists in NFS. Set this to yes to make Dovecot flush
8117 NFS caches whenever needed. If you're using only a single mail server
8119 Defaults to @samp{#f}.
8122 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-nfs-index?
8123 Mail index files also exist in NFS. Setting this to yes requires
8124 @samp{mmap-disable? #t} and @samp{fsync-disable? #f}.
8125 Defaults to @samp{#f}.
8128 @deftypevr {@code{dovecot-configuration} parameter} string lock-method
8129 Locking method for index files. Alternatives are fcntl, flock and
8130 dotlock. Dotlocking uses some tricks which may create more disk I/O
8131 than other locking methods. NFS users: flock doesn't work, remember to
8132 change @samp{mmap-disable}.
8133 Defaults to @samp{"fcntl"}.
8136 @deftypevr {@code{dovecot-configuration} parameter} file-name mail-temp-dir
8137 Directory in which LDA/LMTP temporarily stores incoming mails >128
8139 Defaults to @samp{"/tmp"}.
8142 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer first-valid-uid
8143 Valid UID range for users. This is mostly to make sure that users can't
8144 log in as daemons or other system users. Note that denying root logins is
8145 hardcoded to dovecot binary and can't be done even if @samp{first-valid-uid}
8147 Defaults to @samp{500}.
8150 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer last-valid-uid
8152 Defaults to @samp{0}.
8155 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer first-valid-gid
8156 Valid GID range for users. Users having non-valid GID as primary group ID
8157 aren't allowed to log in. If user belongs to supplementary groups with
8158 non-valid GIDs, those groups are not set.
8159 Defaults to @samp{1}.
8162 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer last-valid-gid
8164 Defaults to @samp{0}.
8167 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-max-keyword-length
8168 Maximum allowed length for mail keyword name. It's only forced when
8169 trying to create new keywords.
8170 Defaults to @samp{50}.
8173 @deftypevr {@code{dovecot-configuration} parameter} colon-separated-file-name-list valid-chroot-dirs
8174 List of directories under which chrooting is allowed for mail
8175 processes (i.e. /var/mail will allow chrooting to /var/mail/foo/bar
8176 too). This setting doesn't affect @samp{login-chroot}
8177 @samp{mail-chroot} or auth chroot settings. If this setting is empty,
8178 "/./" in home dirs are ignored. WARNING: Never add directories here
8179 which local users can modify, that may lead to root exploit. Usually
8180 this should be done only if you don't allow shell access for users.
8181 <doc/wiki/Chrooting.txt>.
8182 Defaults to @samp{()}.
8185 @deftypevr {@code{dovecot-configuration} parameter} string mail-chroot
8186 Default chroot directory for mail processes. This can be overridden
8187 for specific users in user database by giving /./ in user's home
8188 directory (e.g. /home/./user chroots into /home). Note that usually
8189 there is no real need to do chrooting, Dovecot doesn't allow users to
8190 access files outside their mail directory anyway. If your home
8191 directories are prefixed with the chroot directory, append "/." to
8192 @samp{mail-chroot}. <doc/wiki/Chrooting.txt>.
8193 Defaults to @samp{""}.
8196 @deftypevr {@code{dovecot-configuration} parameter} file-name auth-socket-path
8197 UNIX socket path to master authentication server to find users.
8198 This is used by imap (for shared users) and lda.
8199 Defaults to @samp{"/var/run/dovecot/auth-userdb"}.
8202 @deftypevr {@code{dovecot-configuration} parameter} file-name mail-plugin-dir
8203 Directory where to look up mail plugins.
8204 Defaults to @samp{"/usr/lib/dovecot"}.
8207 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mail-plugins
8208 List of plugins to load for all services. Plugins specific to IMAP,
8209 LDA, etc. are added to this list in their own .conf files.
8210 Defaults to @samp{()}.
8213 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-cache-min-mail-count
8214 The minimum number of mails in a mailbox before updates are done to
8215 cache file. This allows optimizing Dovecot's behavior to do less disk
8216 writes at the cost of more disk reads.
8217 Defaults to @samp{0}.
8220 @deftypevr {@code{dovecot-configuration} parameter} string mailbox-idle-check-interval
8221 When IDLE command is running, mailbox is checked once in a while to
8222 see if there are any new mails or other changes. This setting defines
8223 the minimum time to wait between those checks. Dovecot can also use
8224 dnotify, inotify and kqueue to find out immediately when changes
8226 Defaults to @samp{"30 secs"}.
8229 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-save-crlf?
8230 Save mails with CR+LF instead of plain LF. This makes sending those
8231 mails take less CPU, especially with sendfile() syscall with Linux and
8232 FreeBSD. But it also creates a bit more disk I/O which may just make it
8233 slower. Also note that if other software reads the mboxes/maildirs,
8234 they may handle the extra CRs wrong and cause problems.
8235 Defaults to @samp{#f}.
8238 @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-stat-dirs?
8239 By default LIST command returns all entries in maildir beginning
8240 with a dot. Enabling this option makes Dovecot return only entries
8241 which are directories. This is done by stat()ing each entry, so it
8242 causes more disk I/O.
8243 (For systems setting struct @samp{dirent->d_type} this check is free
8244 and it's done always regardless of this setting).
8245 Defaults to @samp{#f}.
8248 @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-copy-with-hardlinks?
8249 When copying a message, do it with hard links whenever possible.
8250 This makes the performance much better, and it's unlikely to have any
8252 Defaults to @samp{#t}.
8255 @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-very-dirty-syncs?
8256 Assume Dovecot is the only MUA accessing Maildir: Scan cur/
8257 directory only when its mtime changes unexpectedly or when we can't find
8259 Defaults to @samp{#f}.
8262 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mbox-read-locks
8263 Which locking methods to use for locking mbox. There are four
8268 Create <mailbox>.lock file. This is the oldest and most NFS-safe
8269 solution. If you want to use /var/mail/ like directory, the users will
8270 need write access to that directory.
8272 Same as dotlock, but if it fails because of permissions or because there
8273 isn't enough disk space, just skip it.
8275 Use this if possible. Works with NFS too if lockd is used.
8277 May not exist in all systems. Doesn't work with NFS.
8279 May not exist in all systems. Doesn't work with NFS.
8282 You can use multiple locking methods; if you do the order they're declared
8283 in is important to avoid deadlocks if other MTAs/MUAs are using multiple
8284 locking methods as well. Some operating systems don't allow using some of
8285 them simultaneously.
8288 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mbox-write-locks
8292 @deftypevr {@code{dovecot-configuration} parameter} string mbox-lock-timeout
8293 Maximum time to wait for lock (all of them) before aborting.
8294 Defaults to @samp{"5 mins"}.
8297 @deftypevr {@code{dovecot-configuration} parameter} string mbox-dotlock-change-timeout
8298 If dotlock exists but the mailbox isn't modified in any way,
8299 override the lock file after this much time.
8300 Defaults to @samp{"2 mins"}.
8303 @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-dirty-syncs?
8304 When mbox changes unexpectedly we have to fully read it to find out
8305 what changed. If the mbox is large this can take a long time. Since
8306 the change is usually just a newly appended mail, it'd be faster to
8307 simply read the new mails. If this setting is enabled, Dovecot does
8308 this but still safely fallbacks to re-reading the whole mbox file
8309 whenever something in mbox isn't how it's expected to be. The only real
8310 downside to this setting is that if some other MUA changes message
8311 flags, Dovecot doesn't notice it immediately. Note that a full sync is
8312 done with SELECT, EXAMINE, EXPUNGE and CHECK commands.
8313 Defaults to @samp{#t}.
8316 @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-very-dirty-syncs?
8317 Like @samp{mbox-dirty-syncs}, but don't do full syncs even with SELECT,
8318 EXAMINE, EXPUNGE or CHECK commands. If this is set,
8319 @samp{mbox-dirty-syncs} is ignored.
8320 Defaults to @samp{#f}.
8323 @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-lazy-writes?
8324 Delay writing mbox headers until doing a full write sync (EXPUNGE
8325 and CHECK commands and when closing the mailbox). This is especially
8326 useful for POP3 where clients often delete all mails. The downside is
8327 that our changes aren't immediately visible to other MUAs.
8328 Defaults to @samp{#t}.
8331 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mbox-min-index-size
8332 If mbox size is smaller than this (e.g. 100k), don't write index
8333 files. If an index file already exists it's still read, just not
8335 Defaults to @samp{0}.
8338 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mdbox-rotate-size
8339 Maximum dbox file size until it's rotated.
8340 Defaults to @samp{2000000}.
8343 @deftypevr {@code{dovecot-configuration} parameter} string mdbox-rotate-interval
8344 Maximum dbox file age until it's rotated. Typically in days. Day
8345 begins from midnight, so 1d = today, 2d = yesterday, etc. 0 = check
8347 Defaults to @samp{"1d"}.
8350 @deftypevr {@code{dovecot-configuration} parameter} boolean mdbox-preallocate-space?
8351 When creating new mdbox files, immediately preallocate their size to
8352 @samp{mdbox-rotate-size}. This setting currently works only in Linux
8353 with some filesystems (ext4, xfs).
8354 Defaults to @samp{#f}.
8357 @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-dir
8358 sdbox and mdbox support saving mail attachments to external files,
8359 which also allows single instance storage for them. Other backends
8360 don't support this for now.
8362 WARNING: This feature hasn't been tested much yet. Use at your own risk.
8364 Directory root where to store mail attachments. Disabled, if empty.
8365 Defaults to @samp{""}.
8368 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-attachment-min-size
8369 Attachments smaller than this aren't saved externally. It's also
8370 possible to write a plugin to disable saving specific attachments
8372 Defaults to @samp{128000}.
8375 @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-fs
8376 Filesystem backend to use for saving attachments:
8379 No SiS done by Dovecot (but this might help FS's own deduplication)
8381 SiS with immediate byte-by-byte comparison during saving
8382 @item sis-queue posix
8383 SiS with delayed comparison and deduplication.
8385 Defaults to @samp{"sis posix"}.
8388 @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-hash
8389 Hash format to use in attachment filenames. You can add any text and
8390 variables: @code{%@{md4@}}, @code{%@{md5@}}, @code{%@{sha1@}},
8391 @code{%@{sha256@}}, @code{%@{sha512@}}, @code{%@{size@}}. Variables can be
8392 truncated, e.g. @code{%@{sha256:80@}} returns only first 80 bits.
8393 Defaults to @samp{"%@{sha1@}"}.
8396 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-process-limit
8398 Defaults to @samp{100}.
8401 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-client-limit
8403 Defaults to @samp{1000}.
8406 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-vsz-limit
8407 Default VSZ (virtual memory size) limit for service processes.
8408 This is mainly intended to catch and kill processes that leak memory
8409 before they eat up everything.
8410 Defaults to @samp{256000000}.
8413 @deftypevr {@code{dovecot-configuration} parameter} string default-login-user
8414 Login user is internally used by login processes. This is the most
8415 untrusted user in Dovecot system. It shouldn't have access to anything
8417 Defaults to @samp{"dovenull"}.
8420 @deftypevr {@code{dovecot-configuration} parameter} string default-internal-user
8421 Internal user is used by unprivileged processes. It should be
8422 separate from login user, so that login processes can't disturb other
8424 Defaults to @samp{"dovecot"}.
8427 @deftypevr {@code{dovecot-configuration} parameter} string ssl?
8428 SSL/TLS support: yes, no, required. <doc/wiki/SSL.txt>.
8429 Defaults to @samp{"required"}.
8432 @deftypevr {@code{dovecot-configuration} parameter} string ssl-cert
8433 PEM encoded X.509 SSL/TLS certificate (public key).
8434 Defaults to @samp{"</etc/dovecot/default.pem"}.
8437 @deftypevr {@code{dovecot-configuration} parameter} string ssl-key
8438 PEM encoded SSL/TLS private key. The key is opened before
8439 dropping root privileges, so keep the key file unreadable by anyone but
8441 Defaults to @samp{"</etc/dovecot/private/default.pem"}.
8444 @deftypevr {@code{dovecot-configuration} parameter} string ssl-key-password
8445 If key file is password protected, give the password here.
8446 Alternatively give it when starting dovecot with -p parameter. Since
8447 this file is often world-readable, you may want to place this setting
8448 instead to a different.
8449 Defaults to @samp{""}.
8452 @deftypevr {@code{dovecot-configuration} parameter} string ssl-ca
8453 PEM encoded trusted certificate authority. Set this only if you
8454 intend to use @samp{ssl-verify-client-cert? #t}. The file should
8455 contain the CA certificate(s) followed by the matching
8456 CRL(s). (e.g. @samp{ssl-ca </etc/ssl/certs/ca.pem}).
8457 Defaults to @samp{""}.
8460 @deftypevr {@code{dovecot-configuration} parameter} boolean ssl-require-crl?
8461 Require that CRL check succeeds for client certificates.
8462 Defaults to @samp{#t}.
8465 @deftypevr {@code{dovecot-configuration} parameter} boolean ssl-verify-client-cert?
8466 Request client to send a certificate. If you also want to require
8467 it, set @samp{auth-ssl-require-client-cert? #t} in auth section.
8468 Defaults to @samp{#f}.
8471 @deftypevr {@code{dovecot-configuration} parameter} string ssl-cert-username-field
8472 Which field from certificate to use for username. commonName and
8473 x500UniqueIdentifier are the usual choices. You'll also need to set
8474 @samp{auth-ssl-username-from-cert? #t}.
8475 Defaults to @samp{"commonName"}.
8478 @deftypevr {@code{dovecot-configuration} parameter} hours ssl-parameters-regenerate
8479 How often to regenerate the SSL parameters file. Generation is
8480 quite CPU intensive operation. The value is in hours, 0 disables
8481 regeneration entirely.
8482 Defaults to @samp{168}.
8485 @deftypevr {@code{dovecot-configuration} parameter} string ssl-protocols
8486 SSL protocols to use.
8487 Defaults to @samp{"!SSLv2"}.
8490 @deftypevr {@code{dovecot-configuration} parameter} string ssl-cipher-list
8492 Defaults to @samp{"ALL:!LOW:!SSLv2:!EXP:!aNULL"}.
8495 @deftypevr {@code{dovecot-configuration} parameter} string ssl-crypto-device
8496 SSL crypto device to use, for valid values run "openssl engine".
8497 Defaults to @samp{""}.
8500 @deftypevr {@code{dovecot-configuration} parameter} string postmaster-address
8501 Address to use when sending rejection mails.
8502 Default is postmaster@@<your domain>. %d expands to recipient domain.
8503 Defaults to @samp{""}.
8506 @deftypevr {@code{dovecot-configuration} parameter} string hostname
8507 Hostname to use in various parts of sent mails (e.g. in Message-Id)
8508 and in LMTP replies. Default is the system's real hostname@@domain.
8509 Defaults to @samp{""}.
8512 @deftypevr {@code{dovecot-configuration} parameter} boolean quota-full-tempfail?
8513 If user is over quota, return with temporary failure instead of
8515 Defaults to @samp{#f}.
8518 @deftypevr {@code{dovecot-configuration} parameter} file-name sendmail-path
8519 Binary to use for sending mails.
8520 Defaults to @samp{"/usr/sbin/sendmail"}.
8523 @deftypevr {@code{dovecot-configuration} parameter} string submission-host
8524 If non-empty, send mails via this SMTP host[:port] instead of
8526 Defaults to @samp{""}.
8529 @deftypevr {@code{dovecot-configuration} parameter} string rejection-subject
8530 Subject: header to use for rejection mails. You can use the same
8531 variables as for @samp{rejection-reason} below.
8532 Defaults to @samp{"Rejected: %s"}.
8535 @deftypevr {@code{dovecot-configuration} parameter} string rejection-reason
8536 Human readable error message for rejection mails. You can use
8549 Defaults to @samp{"Your message to <%t> was automatically rejected:%n%r"}.
8552 @deftypevr {@code{dovecot-configuration} parameter} string recipient-delimiter
8553 Delimiter character between local-part and detail in email
8555 Defaults to @samp{"+"}.
8558 @deftypevr {@code{dovecot-configuration} parameter} string lda-original-recipient-header
8559 Header where the original recipient address (SMTP's RCPT TO:
8560 address) is taken from if not available elsewhere. With dovecot-lda -a
8561 parameter overrides this. A commonly used header for this is
8563 Defaults to @samp{""}.
8566 @deftypevr {@code{dovecot-configuration} parameter} boolean lda-mailbox-autocreate?
8567 Should saving a mail to a nonexistent mailbox automatically create
8569 Defaults to @samp{#f}.
8572 @deftypevr {@code{dovecot-configuration} parameter} boolean lda-mailbox-autosubscribe?
8573 Should automatically created mailboxes be also automatically
8575 Defaults to @samp{#f}.
8578 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer imap-max-line-length
8579 Maximum IMAP command line length. Some clients generate very long
8580 command lines with huge mailboxes, so you may need to raise this if you
8581 get "Too long argument" or "IMAP command line too large" errors
8583 Defaults to @samp{64000}.
8586 @deftypevr {@code{dovecot-configuration} parameter} string imap-logout-format
8587 IMAP logout format string:
8590 total number of bytes read from client
8592 total number of bytes sent to client.
8594 Defaults to @samp{"in=%i out=%o"}.
8597 @deftypevr {@code{dovecot-configuration} parameter} string imap-capability
8598 Override the IMAP CAPABILITY response. If the value begins with '+',
8599 add the given capabilities on top of the defaults (e.g. +XFOO XBAR).
8600 Defaults to @samp{""}.
8603 @deftypevr {@code{dovecot-configuration} parameter} string imap-idle-notify-interval
8604 How long to wait between "OK Still here" notifications when client
8606 Defaults to @samp{"2 mins"}.
8609 @deftypevr {@code{dovecot-configuration} parameter} string imap-id-send
8610 ID field names and values to send to clients. Using * as the value
8611 makes Dovecot use the default value. The following fields have default
8612 values currently: name, version, os, os-version, support-url,
8614 Defaults to @samp{""}.
8617 @deftypevr {@code{dovecot-configuration} parameter} string imap-id-log
8618 ID fields sent by client to log. * means everything.
8619 Defaults to @samp{""}.
8622 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list imap-client-workarounds
8623 Workarounds for various client bugs:
8627 Send EXISTS/RECENT new mail notifications only when replying to NOOP and
8628 CHECK commands. Some clients ignore them otherwise, for example OSX
8629 Mail (<v2.1). Outlook Express breaks more badly though, without this it
8630 may show user "Message no longer in server" errors. Note that OE6
8631 still breaks even with this workaround if synchronization is set to
8634 @item tb-extra-mailbox-sep
8635 Thunderbird gets somehow confused with LAYOUT=fs (mbox and dbox) and
8636 adds extra @samp{/} suffixes to mailbox names. This option causes Dovecot to
8637 ignore the extra @samp{/} instead of treating it as invalid mailbox name.
8640 Show \Noselect flags for LSUB replies with LAYOUT=fs (e.g. mbox).
8641 This makes Thunderbird realize they aren't selectable and show them
8642 greyed out, instead of only later giving "not selectable" popup error.
8644 Defaults to @samp{()}.
8647 @deftypevr {@code{dovecot-configuration} parameter} string imap-urlauth-host
8648 Host allowed in URLAUTH URLs sent by client. "*" allows all.
8649 Defaults to @samp{""}.
8653 Whew! Lots of configuration options. The nice thing about it though is
8654 that GuixSD has a complete interface to Dovecot's configuration
8655 language. This allows not only a nice way to declare configurations,
8656 but also offers reflective capabilities as well: users can write code to
8657 inspect and transform configurations from within Scheme.
8659 However, it could be that you just want to get a @code{dovecot.conf} up
8660 and running. In that case, you can pass an
8661 @code{opaque-dovecot-configuration} as the @code{#:config} paramter to
8662 @code{dovecot-service}. As its name indicates, an opaque configuration
8663 does not have easy reflective capabilities.
8665 Available @code{opaque-dovecot-configuration} fields are:
8667 @deftypevr {@code{opaque-dovecot-configuration} parameter} package dovecot
8668 The dovecot package.
8671 @deftypevr {@code{opaque-dovecot-configuration} parameter} string string
8672 The contents of the @code{dovecot.conf}, as a string.
8675 For example, if your @code{dovecot.conf} is just the empty string, you
8676 could instantiate a dovecot service like this:
8679 (dovecot-service #:config
8680 (opaque-dovecot-configuration
8685 @subsubsection Web Services
8687 The @code{(gnu services web)} module provides the following service:
8689 @deffn {Scheme Procedure} nginx-service [#:nginx nginx] @
8690 [#:log-directory ``/var/log/nginx''] @
8691 [#:run-directory ``/var/run/nginx''] @
8694 Return a service that runs @var{nginx}, the nginx web server.
8696 The nginx daemon loads its runtime configuration from @var{config-file}.
8697 Log files are written to @var{log-directory} and temporary runtime data
8698 files are written to @var{run-directory}. For proper operation, these
8699 arguments should match what is in @var{config-file} to ensure that the
8700 directories are created when the service is activated.
8704 @node Various Services
8705 @subsubsection Various Services
8707 The @code{(gnu services lirc)} module provides the following service.
8709 @deffn {Scheme Procedure} lirc-service [#:lirc lirc] @
8710 [#:device #f] [#:driver #f] [#:config-file #f] @
8711 [#:extra-options '()]
8712 Return a service that runs @url{http://www.lirc.org,LIRC}, a daemon that
8713 decodes infrared signals from remote controls.
8715 Optionally, @var{device}, @var{driver} and @var{config-file}
8716 (configuration file name) may be specified. See @command{lircd} manual
8719 Finally, @var{extra-options} is a list of additional command-line options
8720 passed to @command{lircd}.
8724 @node Setuid Programs
8725 @subsection Setuid Programs
8727 @cindex setuid programs
8728 Some programs need to run with ``root'' privileges, even when they are
8729 launched by unprivileged users. A notorious example is the
8730 @command{passwd} program, which users can run to change their
8731 password, and which needs to access the @file{/etc/passwd} and
8732 @file{/etc/shadow} files---something normally restricted to root, for
8733 obvious security reasons. To address that, these executables are
8734 @dfn{setuid-root}, meaning that they always run with root privileges
8735 (@pxref{How Change Persona,,, libc, The GNU C Library Reference Manual},
8736 for more info about the setuid mechanism.)
8738 The store itself @emph{cannot} contain setuid programs: that would be a
8739 security issue since any user on the system can write derivations that
8740 populate the store (@pxref{The Store}). Thus, a different mechanism is
8741 used: instead of changing the setuid bit directly on files that are in
8742 the store, we let the system administrator @emph{declare} which programs
8743 should be setuid root.
8745 The @code{setuid-programs} field of an @code{operating-system}
8746 declaration contains a list of G-expressions denoting the names of
8747 programs to be setuid-root (@pxref{Using the Configuration System}).
8748 For instance, the @command{passwd} program, which is part of the Shadow
8749 package, can be designated by this G-expression (@pxref{G-Expressions}):
8752 #~(string-append #$shadow "/bin/passwd")
8755 A default set of setuid programs is defined by the
8756 @code{%setuid-programs} variable of the @code{(gnu system)} module.
8758 @defvr {Scheme Variable} %setuid-programs
8759 A list of G-expressions denoting common programs that are setuid-root.
8761 The list includes commands such as @command{passwd}, @command{ping},
8762 @command{su}, and @command{sudo}.
8765 Under the hood, the actual setuid programs are created in the
8766 @file{/run/setuid-programs} directory at system activation time. The
8767 files in this directory refer to the ``real'' binaries, which are in the
8770 @node X.509 Certificates
8771 @subsection X.509 Certificates
8773 @cindex HTTPS, certificates
8774 @cindex X.509 certificates
8776 Web servers available over HTTPS (that is, HTTP over the transport-layer
8777 security mechanism, TLS) send client programs an @dfn{X.509 certificate}
8778 that the client can then use to @emph{authenticate} the server. To do
8779 that, clients verify that the server's certificate is signed by a
8780 so-called @dfn{certificate authority} (CA). But to verify the CA's
8781 signature, clients must have first acquired the CA's certificate.
8783 Web browsers such as GNU@tie{}IceCat include their own set of CA
8784 certificates, such that they are able to verify CA signatures
8787 However, most other programs that can talk HTTPS---@command{wget},
8788 @command{git}, @command{w3m}, etc.---need to be told where CA
8789 certificates can be found.
8791 @cindex @code{nss-certs}
8792 In GuixSD, this is done by adding a package that provides certificates
8793 to the @code{packages} field of the @code{operating-system} declaration
8794 (@pxref{operating-system Reference}). GuixSD includes one such package,
8795 @code{nss-certs}, which is a set of CA certificates provided as part of
8796 Mozilla's Network Security Services.
8798 Note that it is @emph{not} part of @var{%base-packages}, so you need to
8799 explicitly add it. The @file{/etc/ssl/certs} directory, which is where
8800 most applications and libraries look for certificates by default, points
8801 to the certificates installed globally.
8803 Unprivileged users can also install their own certificate package in
8804 their profile. A number of environment variables need to be defined so
8805 that applications and libraries know where to find them. Namely, the
8806 OpenSSL library honors the @code{SSL_CERT_DIR} and @code{SSL_CERT_FILE}
8807 variables. Some applications add their own environment variables; for
8808 instance, the Git version control system honors the certificate bundle
8809 pointed to by the @code{GIT_SSL_CAINFO} environment variable.
8812 @node Name Service Switch
8813 @subsection Name Service Switch
8815 @cindex name service switch
8817 The @code{(gnu system nss)} module provides bindings to the
8818 configuration file of libc's @dfn{name service switch} or @dfn{NSS}
8819 (@pxref{NSS Configuration File,,, libc, The GNU C Library Reference
8820 Manual}). In a nutshell, the NSS is a mechanism that allows libc to be
8821 extended with new ``name'' lookup methods for system databases, which
8822 includes host names, service names, user accounts, and more (@pxref{Name
8823 Service Switch, System Databases and Name Service Switch,, libc, The GNU
8824 C Library Reference Manual}).
8826 The NSS configuration specifies, for each system database, which lookup
8827 method is to be used, and how the various methods are chained
8828 together---for instance, under which circumstances NSS should try the
8829 next method in the list. The NSS configuration is given in the
8830 @code{name-service-switch} field of @code{operating-system} declarations
8831 (@pxref{operating-system Reference, @code{name-service-switch}}).
8834 @cindex .local, host name lookup
8835 As an example, the declaration below configures the NSS to use the
8836 @uref{http://0pointer.de/lennart/projects/nss-mdns/, @code{nss-mdns}
8837 back-end}, which supports host name lookups over multicast DNS (mDNS)
8838 for host names ending in @code{.local}:
8841 (name-service-switch
8842 (hosts (list %files ;first, check /etc/hosts
8844 ;; If the above did not succeed, try
8845 ;; with 'mdns_minimal'.
8847 (name "mdns_minimal")
8849 ;; 'mdns_minimal' is authoritative for
8850 ;; '.local'. When it returns "not found",
8851 ;; no need to try the next methods.
8852 (reaction (lookup-specification
8853 (not-found => return))))
8855 ;; Then fall back to DNS.
8859 ;; Finally, try with the "full" 'mdns'.
8864 Don't worry: the @code{%mdns-host-lookup-nss} variable (see below)
8865 contains this configuration, so you won't have to type it if all you
8866 want is to have @code{.local} host lookup working.
8868 Note that, in this case, in addition to setting the
8869 @code{name-service-switch} of the @code{operating-system} declaration,
8870 you also need to use @code{avahi-service} (@pxref{Networking Services,
8871 @code{avahi-service}}), or @var{%desktop-services}, which includes it
8872 (@pxref{Desktop Services}). Doing this makes @code{nss-mdns} accessible
8873 to the name service cache daemon (@pxref{Base Services,
8874 @code{nscd-service}}).
8876 For convenience, the following variables provide typical NSS
8879 @defvr {Scheme Variable} %default-nss
8880 This is the default name service switch configuration, a
8881 @code{name-service-switch} object.
8884 @defvr {Scheme Variable} %mdns-host-lookup-nss
8885 This is the name service switch configuration with support for host name
8886 lookup over multicast DNS (mDNS) for host names ending in @code{.local}.
8889 The reference for name service switch configuration is given below. It
8890 is a direct mapping of the C library's configuration file format, so
8891 please refer to the C library manual for more information (@pxref{NSS
8892 Configuration File,,, libc, The GNU C Library Reference Manual}).
8893 Compared to libc's NSS configuration file format, it has the advantage
8894 not only of adding this warm parenthetic feel that we like, but also
8895 static checks: you'll know about syntax errors and typos as soon as you
8896 run @command{guix system}.
8898 @deftp {Data Type} name-service-switch
8900 This is the data type representation the configuration of libc's name
8901 service switch (NSS). Each field below represents one of the supported
8918 The system databases handled by the NSS. Each of these fields must be a
8919 list of @code{<name-service>} objects (see below.)
8923 @deftp {Data Type} name-service
8925 This is the data type representing an actual name service and the
8926 associated lookup action.
8930 A string denoting the name service (@pxref{Services in the NSS
8931 configuration,,, libc, The GNU C Library Reference Manual}).
8933 Note that name services listed here must be visible to nscd. This is
8934 achieved by passing the @code{#:name-services} argument to
8935 @code{nscd-service} the list of packages providing the needed name
8936 services (@pxref{Base Services, @code{nscd-service}}).
8939 An action specified using the @code{lookup-specification} macro
8940 (@pxref{Actions in the NSS configuration,,, libc, The GNU C Library
8941 Reference Manual}). For example:
8944 (lookup-specification (unavailable => continue)
8945 (success => return))
8950 @node Initial RAM Disk
8951 @subsection Initial RAM Disk
8953 @cindex initial RAM disk (initrd)
8954 @cindex initrd (initial RAM disk)
8955 For bootstrapping purposes, the Linux-Libre kernel is passed an
8956 @dfn{initial RAM disk}, or @dfn{initrd}. An initrd contains a temporary
8957 root file system, as well as an initialization script. The latter is
8958 responsible for mounting the real root file system, and for loading any
8959 kernel modules that may be needed to achieve that.
8961 The @code{initrd} field of an @code{operating-system} declaration allows
8962 you to specify which initrd you would like to use. The @code{(gnu
8963 system linux-initrd)} module provides two ways to build an initrd: the
8964 high-level @code{base-initrd} procedure, and the low-level
8965 @code{expression->initrd} procedure.
8967 The @code{base-initrd} procedure is intended to cover most common uses.
8968 For example, if you want to add a bunch of kernel modules to be loaded
8969 at boot time, you can define the @code{initrd} field of the operating
8970 system declaration like this:
8973 (initrd (lambda (file-systems . rest)
8974 ;; Create a standard initrd that has modules "foo.ko"
8975 ;; and "bar.ko", as well as their dependencies, in
8976 ;; addition to the modules available by default.
8977 (apply base-initrd file-systems
8978 #:extra-modules '("foo" "bar")
8982 The @code{base-initrd} procedure also handles common use cases that
8983 involves using the system as a QEMU guest, or as a ``live'' system whose
8984 root file system is volatile.
8986 The initial RAM disk produced by @code{base-initrd} honors several
8987 options passed on the Linux kernel command line (that is, arguments
8988 passed @i{via} GRUB's @code{linux} command, or with QEMU's
8989 @code{-append} option), notably:
8992 @item --load=@var{boot}
8993 Tell the initial RAM disk to load @var{boot}, a file containing a Scheme
8994 program, once it has mounted the root file system.
8996 GuixSD uses this option to yield control to a boot program that runs the
8997 service activation programs and then spawns the GNU@tie{}Shepherd, the
8998 initialization system.
9000 @item --root=@var{root}
9001 Mount @var{root} as the root file system. @var{root} can be a device
9002 device name like @code{/dev/sda1}, a partition label, or a partition
9005 @item --system=@var{system}
9006 Have @file{/run/booted-system} and @file{/run/current-system} point to
9009 @item modprobe.blacklist=@var{modules}@dots{}
9010 @cindex module, black-listing
9011 @cindex black list, of kernel modules
9012 Instruct the initial RAM disk as well as the @command{modprobe} command
9013 (from the kmod package) to refuse to load @var{modules}. @var{modules}
9014 must be a comma-separated list of module names---e.g.,
9015 @code{usbkbd,9pnet}.
9018 Start a read-eval-print loop (REPL) from the initial RAM disk before it
9019 tries to load kernel modules and to mount the root file system. Our
9020 marketing team calls it @dfn{boot-to-Guile}. The Schemer in you will
9021 love it. @xref{Using Guile Interactively,,, guile, GNU Guile Reference
9022 Manual}, for more information on Guile's REPL.
9026 Now that you know all the features that initial RAM disks produced by
9027 @code{base-initrd} provide, here is how to use it and customize it
9030 @deffn {Monadic Procedure} base-initrd @var{file-systems} @
9031 [#:qemu-networking? #f] [#:virtio? #t] [#:volatile-root? #f] @
9032 [#:extra-modules '()] [#:mapped-devices '()]
9033 Return a monadic derivation that builds a generic initrd. @var{file-systems} is
9034 a list of file-systems to be mounted by the initrd, possibly in addition to
9035 the root file system specified on the kernel command line via @code{--root}.
9036 @var{mapped-devices} is a list of device mappings to realize before
9037 @var{file-systems} are mounted (@pxref{Mapped Devices}).
9039 When @var{qemu-networking?} is true, set up networking with the standard QEMU
9040 parameters. When @var{virtio?} is true, load additional modules so the initrd can
9041 be used as a QEMU guest with para-virtualized I/O drivers.
9043 When @var{volatile-root?} is true, the root file system is writable but any changes
9046 The initrd is automatically populated with all the kernel modules necessary
9047 for @var{file-systems} and for the given options. However, additional kernel
9048 modules can be listed in @var{extra-modules}. They will be added to the initrd, and
9049 loaded at boot time in the order in which they appear.
9052 Needless to say, the initrds we produce and use embed a
9053 statically-linked Guile, and the initialization program is a Guile
9054 program. That gives a lot of flexibility. The
9055 @code{expression->initrd} procedure builds such an initrd, given the
9056 program to run in that initrd.
9058 @deffn {Monadic Procedure} expression->initrd @var{exp} @
9059 [#:guile %guile-static-stripped] [#:name "guile-initrd"] @
9061 Return a derivation that builds a Linux initrd (a gzipped cpio archive)
9062 containing @var{guile} and that evaluates @var{exp}, a G-expression,
9063 upon booting. All the derivations referenced by @var{exp} are
9064 automatically copied to the initrd.
9066 @var{modules} is a list of Guile module names to be embedded in the
9070 @node GRUB Configuration
9071 @subsection GRUB Configuration
9076 The operating system uses GNU@tie{}GRUB as its boot loader
9077 (@pxref{Overview, overview of GRUB,, grub, GNU GRUB Manual}). It is
9078 configured using @code{grub-configuration} declarations. This data type
9079 is exported by the @code{(gnu system grub)} module, and described below.
9081 @deftp {Data Type} grub-configuration
9082 The type of a GRUB configuration declaration.
9087 This is a string denoting the boot device. It must be a device name
9088 understood by the @command{grub-install} command, such as
9089 @code{/dev/sda} or @code{(hd0)} (@pxref{Invoking grub-install,,, grub,
9092 @item @code{menu-entries} (default: @code{()})
9093 A possibly empty list of @code{menu-entry} objects (see below), denoting
9094 entries to appear in the GRUB boot menu, in addition to the current
9095 system entry and the entry pointing to previous system generations.
9097 @item @code{default-entry} (default: @code{0})
9098 The index of the default boot menu entry. Index 0 is for the current
9101 @item @code{timeout} (default: @code{5})
9102 The number of seconds to wait for keyboard input before booting. Set to
9103 0 to boot immediately, and to -1 to wait indefinitely.
9105 @item @code{theme} (default: @var{%default-theme})
9106 The @code{grub-theme} object describing the theme to use.
9111 Should you want to list additional boot menu entries @i{via} the
9112 @code{menu-entries} field above, you will need to create them with the
9113 @code{menu-entry} form:
9115 @deftp {Data Type} menu-entry
9116 The type of an entry in the GRUB boot menu.
9121 The label to show in the menu---e.g., @code{"GNU"}.
9124 The Linux kernel to boot.
9126 @item @code{linux-arguments} (default: @code{()})
9127 The list of extra Linux kernel command-line arguments---e.g.,
9128 @code{("console=ttyS0")}.
9131 A G-Expression or string denoting the file name of the initial RAM disk
9132 to use (@pxref{G-Expressions}).
9137 @c FIXME: Write documentation once it's stable.
9138 Themes are created using the @code{grub-theme} form, which is not
9141 @defvr {Scheme Variable} %default-theme
9142 This is the default GRUB theme used by the operating system, with a
9143 fancy background image displaying the GNU and Guix logos.
9147 @node Invoking guix system
9148 @subsection Invoking @code{guix system}
9150 Once you have written an operating system declaration, as seen in the
9151 previous section, it can be @dfn{instantiated} using the @command{guix
9152 system} command. The synopsis is:
9155 guix system @var{options}@dots{} @var{action} @var{file}
9158 @var{file} must be the name of a file containing an
9159 @code{operating-system} declaration. @var{action} specifies how the
9160 operating system is instantiate. Currently the following values are
9165 Build the operating system described in @var{file}, activate it, and
9166 switch to it@footnote{This action is usable only on systems already
9169 This effects all the configuration specified in @var{file}: user
9170 accounts, system services, global package list, setuid programs, etc.
9172 It also adds a GRUB menu entry for the new OS configuration, and moves
9173 entries for older configurations to a submenu---unless
9174 @option{--no-grub} is passed.
9176 @c The paragraph below refers to the problem discussed at
9177 @c <http://lists.gnu.org/archive/html/guix-devel/2014-08/msg00057.html>.
9178 It is highly recommended to run @command{guix pull} once before you run
9179 @command{guix system reconfigure} for the first time (@pxref{Invoking
9180 guix pull}). Failing to do that you would see an older version of Guix
9181 once @command{reconfigure} has completed.
9184 Build the operating system's derivation, which includes all the
9185 configuration files and programs needed to boot and run the system.
9186 This action does not actually install anything.
9189 Populate the given directory with all the files necessary to run the
9190 operating system specified in @var{file}. This is useful for first-time
9191 installations of GuixSD. For instance:
9194 guix system init my-os-config.scm /mnt
9197 copies to @file{/mnt} all the store items required by the configuration
9198 specified in @file{my-os-config.scm}. This includes configuration
9199 files, packages, and so on. It also creates other essential files
9200 needed for the system to operate correctly---e.g., the @file{/etc},
9201 @file{/var}, and @file{/run} directories, and the @file{/bin/sh} file.
9203 This command also installs GRUB on the device specified in
9204 @file{my-os-config}, unless the @option{--no-grub} option was passed.
9207 @cindex virtual machine
9209 @anchor{guix system vm}
9210 Build a virtual machine that contain the operating system declared in
9211 @var{file}, and return a script to run that virtual machine (VM).
9212 Arguments given to the script are passed as is to QEMU.
9214 The VM shares its store with the host system.
9216 Additional file systems can be shared between the host and the VM using
9217 the @code{--share} and @code{--expose} command-line options: the former
9218 specifies a directory to be shared with write access, while the latter
9219 provides read-only access to the shared directory.
9221 The example below creates a VM in which the user's home directory is
9222 accessible read-only, and where the @file{/exchange} directory is a
9223 read-write mapping of the host's @file{$HOME/tmp}:
9226 guix system vm my-config.scm \
9227 --expose=$HOME --share=$HOME/tmp=/exchange
9230 On GNU/Linux, the default is to boot directly to the kernel; this has
9231 the advantage of requiring only a very tiny root disk image since the
9232 host's store can then be mounted.
9234 The @code{--full-boot} option forces a complete boot sequence, starting
9235 with the bootloader. This requires more disk space since a root image
9236 containing at least the kernel, initrd, and bootloader data files must
9237 be created. The @code{--image-size} option can be used to specify the
9242 Return a virtual machine or disk image of the operating system declared
9243 in @var{file} that stands alone. Use the @option{--image-size} option
9244 to specify the size of the image.
9246 When using @code{vm-image}, the returned image is in qcow2 format, which
9247 the QEMU emulator can efficiently use. @xref{Running GuixSD in a VM},
9248 for more information on how to run the image in a virtual machine.
9250 When using @code{disk-image}, a raw disk image is produced; it can be
9251 copied as is to a USB stick, for instance. Assuming @code{/dev/sdc} is
9252 the device corresponding to a USB stick, one can copy the image on it
9253 using the following command:
9256 # dd if=$(guix system disk-image my-os.scm) of=/dev/sdc
9260 Return a script to run the operating system declared in @var{file}
9261 within a container. Containers are a set of lightweight isolation
9262 mechanisms provided by the kernel Linux-libre. Containers are
9263 substantially less resource-demanding than full virtual machines since
9264 the kernel, shared objects, and other resources can be shared with the
9265 host system; this also means they provide thinner isolation.
9267 Currently, the script must be run as root in order to support more than
9268 a single user and group. The container shares its store with the host
9271 As with the @code{vm} action (@pxref{guix system vm}), additional file
9272 systems to be shared between the host and container can be specified
9273 using the @option{--share} and @option{--expose} options:
9276 guix system container my-config.scm \
9277 --expose=$HOME --share=$HOME/tmp=/exchange
9281 This option requires Linux-libre 3.19 or newer.
9286 @var{options} can contain any of the common build options (@pxref{Common
9287 Build Options}). In addition, @var{options} can contain one of the
9291 @item --system=@var{system}
9292 @itemx -s @var{system}
9293 Attempt to build for @var{system} instead of the host's system type.
9294 This works as per @command{guix build} (@pxref{Invoking guix build}).
9298 Return the derivation file name of the given operating system without
9301 @item --image-size=@var{size}
9302 For the @code{vm-image} and @code{disk-image} actions, create an image
9303 of the given @var{size}. @var{size} may be a number of bytes, or it may
9304 include a unit as a suffix (@pxref{Block size, size specifications,,
9305 coreutils, GNU Coreutils}).
9307 @item --on-error=@var{strategy}
9308 Apply @var{strategy} when an error occurs when reading @var{file}.
9309 @var{strategy} may be one of the following:
9312 @item nothing-special
9313 Report the error concisely and exit. This is the default strategy.
9316 Likewise, but also display a backtrace.
9319 Report the error and enter Guile's debugger. From there, you can run
9320 commands such as @code{,bt} to get a backtrace, @code{,locals} to
9321 display local variable values, and more generally inspect the program's
9322 state. @xref{Debug Commands,,, guile, GNU Guile Reference Manual}, for
9323 a list of available debugging commands.
9327 Note that all the actions above, except @code{build} and @code{init},
9328 rely on KVM support in the Linux-Libre kernel. Specifically, the
9329 machine should have hardware virtualization support, the corresponding
9330 KVM kernel module should be loaded, and the @file{/dev/kvm} device node
9331 must exist and be readable and writable by the user and by the daemon's
9334 Once you have built, configured, re-configured, and re-re-configured
9335 your GuixSD installation, you may find it useful to list the operating
9336 system generations available on disk---and that you can choose from the
9341 @item list-generations
9342 List a summary of each generation of the operating system available on
9343 disk, in a human-readable way. This is similar to the
9344 @option{--list-generations} option of @command{guix package}
9345 (@pxref{Invoking guix package}).
9347 Optionally, one can specify a pattern, with the same syntax that is used
9348 in @command{guix package --list-generations}, to restrict the list of
9349 generations displayed. For instance, the following command displays
9350 generations up to 10-day old:
9353 $ guix system list-generations 10d
9358 The @command{guix system} command has even more to offer! The following
9359 sub-commands allow you to visualize how your system services relate to
9362 @anchor{system-extension-graph}
9365 @item extension-graph
9366 Emit in Dot/Graphviz format to standard output the @dfn{service
9367 extension graph} of the operating system defined in @var{file}
9368 (@pxref{Service Composition}, for more information on service
9374 $ guix system extension-graph @var{file} | dot -Tpdf > services.pdf
9377 produces a PDF file showing the extension relations among services.
9379 @anchor{system-shepherd-graph}
9380 @item shepherd-graph
9381 Emit in Dot/Graphviz format to standard output the @dfn{dependency
9382 graph} of shepherd services of the operating system defined in
9383 @var{file}. @xref{Shepherd Services}, for more information and for an
9388 @node Running GuixSD in a VM
9389 @subsection Running GuixSD in a virtual machine
9391 One way to run GuixSD in a virtual machine (VM) is to build a GuixSD
9392 virtual machine image using @command{guix system vm-image}
9393 (@pxref{Invoking guix system}). The returned image is in qcow2 format,
9394 which the @uref{http://qemu.org/, QEMU emulator} can efficiently use.
9396 To run the image in QEMU, copy it out of the store (@pxref{The Store})
9397 and give yourself permission to write to the copy. When invoking QEMU,
9398 you must choose a system emulator that is suitable for your hardware
9399 platform. Here is a minimal QEMU invocation that will boot the result
9400 of @command{guix system vm-image} on x86_64 hardware:
9403 $ qemu-system-x86_64 \
9404 -net user -net nic,model=virtio \
9405 -enable-kvm -m 256 /tmp/qemu-image
9408 Here is what each of these options means:
9411 @item qemu-system-x86_64
9412 This specifies the hardware platform to emulate. This should match the
9416 Enable the unprivileged user-mode network stack. The guest OS can
9417 access the host but not vice versa. This is the simplest way to get the
9418 guest OS online. If you don't choose a network stack, the boot will
9421 @item -net nic,model=virtio
9422 You must create a network interface of a given model. If you don't
9423 create a NIC, the boot will fail. Assuming your hardware platform is
9424 x86_64, you can get a list of available NIC models by running
9425 @command{qemu-system-x86_64 -net nic,model=help}.
9428 If your system has hardware virtualization extensions, enabling the
9429 Linux kernel's virtual machine support (KVM) will make things run
9433 RAM available to the guest OS, in mebibytes. Defaults to 128@tie{}MiB,
9434 which may be insufficent for some operations.
9436 @item /tmp/qemu-image
9437 The file name of the qcow2 image.
9440 @node Defining Services
9441 @subsection Defining Services
9443 The previous sections show the available services and how one can combine
9444 them in an @code{operating-system} declaration. But how do we define
9445 them in the first place? And what is a service anyway?
9448 * Service Composition:: The model for composing services.
9449 * Service Types and Services:: Types and services.
9450 * Service Reference:: API reference.
9451 * Shepherd Services:: A particular type of service.
9454 @node Service Composition
9455 @subsubsection Service Composition
9459 Here we define a @dfn{service} as, broadly, something that extends the
9460 operating system's functionality. Often a service is a process---a
9461 @dfn{daemon}---started when the system boots: a secure shell server, a
9462 Web server, the Guix build daemon, etc. Sometimes a service is a daemon
9463 whose execution can be triggered by another daemon---e.g., an FTP server
9464 started by @command{inetd} or a D-Bus service activated by
9465 @command{dbus-daemon}. Occasionally, a service does not map to a
9466 daemon. For instance, the ``account'' service collects user accounts
9467 and makes sure they exist when the system runs; the ``udev'' service
9468 collects device management rules and makes them available to the eudev
9469 daemon; the @file{/etc} service populates the system's @file{/etc}
9472 @cindex service extensions
9473 GuixSD services are connected by @dfn{extensions}. For instance, the
9474 secure shell service @emph{extends} the Shepherd---GuixSD's
9475 initialization system, running as PID@tie{}1---by giving it the command
9476 lines to start and stop the secure shell daemon (@pxref{Networking
9477 Services, @code{lsh-service}}); the UPower service extends the D-Bus
9478 service by passing it its @file{.service} specification, and extends the
9479 udev service by passing it device management rules (@pxref{Desktop
9480 Services, @code{upower-service}}); the Guix daemon service extends the
9481 Shepherd by passing it the command lines to start and stop the daemon,
9482 and extends the account service by passing it a list of required build
9483 user accounts (@pxref{Base Services}).
9485 All in all, services and their ``extends'' relations form a directed
9486 acyclic graph (DAG). If we represent services as boxes and extensions
9487 as arrows, a typical system might provide something like this:
9489 @image{images/service-graph,,5in,Typical service extension graph.}
9491 @cindex system service
9492 At the bottom, we see the @dfn{system service}, which produces the
9493 directory containing everything to run and boot the system, as returned
9494 by the @command{guix system build} command. @xref{Service Reference},
9495 to learn about the other service types shown here.
9496 @xref{system-extension-graph, the @command{guix system extension-graph}
9497 command}, for information on how to generate this representation for a
9498 particular operating system definition.
9500 @cindex service types
9501 Technically, developers can define @dfn{service types} to express these
9502 relations. There can be any number of services of a given type on the
9503 system---for instance, a system running two instances of the GNU secure
9504 shell server (lsh) has two instances of @var{lsh-service-type}, with
9505 different parameters.
9507 The following section describes the programming interface for service
9510 @node Service Types and Services
9511 @subsubsection Service Types and Services
9513 A @dfn{service type} is a node in the DAG described above. Let us start
9514 with a simple example, the service type for the Guix build daemon
9515 (@pxref{Invoking guix-daemon}):
9518 (define guix-service-type
9522 (list (service-extension shepherd-root-service-type guix-shepherd-service)
9523 (service-extension account-service-type guix-accounts)
9524 (service-extension activation-service-type guix-activation)))))
9528 It defines a two things:
9532 A name, whose sole purpose is to make inspection and debugging easier.
9535 A list of @dfn{service extensions}, where each extension designates the
9536 target service type and a procedure that, given the service's
9537 parameters, returns a list of object to extend the service of that type.
9539 Every service type has at least one service extension. The only
9540 exception is the @dfn{boot service type}, which is the ultimate service.
9543 In this example, @var{guix-service-type} extends three services:
9546 @item shepherd-root-service-type
9547 The @var{guix-shepherd-service} procedure defines how the Shepherd
9548 service is extended. Namely, it returns a @code{<shepherd-service>}
9549 object that defines how @command{guix-daemon} is started and stopped
9550 (@pxref{Shepherd Services}).
9552 @item account-service-type
9553 This extension for this service is computed by @var{guix-accounts},
9554 which returns a list of @code{user-group} and @code{user-account}
9555 objects representing the build user accounts (@pxref{Invoking
9558 @item activation-service-type
9559 Here @var{guix-activation} is a procedure that returns a gexp, which is
9560 a code snippet to run at ``activation time''---e.g., when the service is
9564 A service of this type is instantiated like this:
9567 (service guix-service-type
9570 (use-substitutes? #f)))
9573 The second argument to the @code{service} form is a value representing
9574 the parameters of this specific service instance.
9575 @xref{guix-configuration-type, @code{guix-configuration}}, for
9576 information about the @code{guix-configuration} data type.
9578 @var{guix-service-type} is quite simple because it extends other
9579 services but is not extensible itself.
9581 @c @subsubsubsection Extensible Service Types
9583 The service type for an @emph{extensible} service looks like this:
9586 (define udev-service-type
9587 (service-type (name 'udev)
9589 (list (service-extension shepherd-root-service-type
9590 udev-shepherd-service)))
9592 (compose concatenate) ;concatenate the list of rules
9593 (extend (lambda (config rules)
9595 (($ <udev-configuration> udev initial-rules)
9597 (udev udev) ;the udev package to use
9598 (rules (append initial-rules rules)))))))))
9601 This is the service type for the
9602 @uref{https://wiki.gentoo.org/wiki/Project:Eudev, eudev device
9603 management daemon}. Compared to the previous example, in addition to an
9604 extension of @var{shepherd-root-service-type}, we see two new fields:
9608 This is the procedure to @dfn{compose} the list of extensions to
9609 services of this type.
9611 Services can extend the udev service by passing it lists of rules; we
9612 compose those extensions simply by concatenating them.
9615 This procedure defines how the service's value is @dfn{extended} with
9616 the composition of the extensions.
9618 Udev extensions are composed into a list of rules, but the udev service
9619 value is itself a @code{<udev-configuration>} record. So here, we
9620 extend that record by appending the list of rules is contains to the
9621 list of contributed rules.
9624 There can be only one instance of an extensible service type such as
9625 @var{udev-service-type}. If there were more, the
9626 @code{service-extension} specifications would be ambiguous.
9628 Still here? The next section provides a reference of the programming
9629 interface for services.
9631 @node Service Reference
9632 @subsubsection Service Reference
9634 We have seen an overview of service types (@pxref{Service Types and
9635 Services}). This section provides a reference on how to manipulate
9636 services and service types. This interface is provided by the
9637 @code{(gnu services)} module.
9639 @deffn {Scheme Procedure} service @var{type} @var{value}
9640 Return a new service of @var{type}, a @code{<service-type>} object (see
9641 below.) @var{value} can be any object; it represents the parameters of
9642 this particular service instance.
9645 @deffn {Scheme Procedure} service? @var{obj}
9646 Return true if @var{obj} is a service.
9649 @deffn {Scheme Procedure} service-kind @var{service}
9650 Return the type of @var{service}---i.e., a @code{<service-type>} object.
9653 @deffn {Scheme Procedure} service-parameters @var{service}
9654 Return the value associated with @var{service}. It represents its
9658 Here is an example of how a service is created and manipulated:
9662 (service nginx-service-type
9663 (nginx-configuration
9665 (log-directory log-directory)
9666 (run-directory run-directory)
9667 (file config-file))))
9672 (eq? (service-kind s) nginx-service-type)
9676 The @code{modify-services} form provides a handy way to change the
9677 parameters of some of the services of a list such as
9678 @var{%base-services} (@pxref{Base Services, @code{%base-services}}). Of
9679 course, you could always use standard list combinators such as
9680 @code{map} and @code{fold} to do that (@pxref{SRFI-1, List Library,,
9681 guile, GNU Guile Reference Manual}); @code{modify-services} simply
9682 provides a more concise form for this common pattern.
9684 @deffn {Scheme Syntax} modify-services @var{services} @
9685 (@var{type} @var{variable} => @var{body}) @dots{}
9687 Modify the services listed in @var{services} according to the given
9688 clauses. Each clause has the form:
9691 (@var{type} @var{variable} => @var{body})
9694 where @var{type} is a service type, such as @var{guix-service-type}, and
9695 @var{variable} is an identifier that is bound within @var{body} to the
9696 value of the service of that @var{type}. @xref{Using the Configuration
9697 System}, for an example.
9699 This is a shorthand for:
9702 (map (lambda (service) @dots{}) @var{services})
9706 Next comes the programming interface for service types. This is
9707 something you want to know when writing new service definitions, but not
9708 necessarily when simply looking for ways to customize your
9709 @code{operating-system} declaration.
9711 @deftp {Data Type} service-type
9712 @cindex service type
9713 This is the representation of a @dfn{service type} (@pxref{Service Types
9718 This is a symbol, used only to simplify inspection and debugging.
9720 @item @code{extensions}
9721 A non-empty list of @code{<service-extension>} objects (see below.)
9723 @item @code{compose} (default: @code{#f})
9724 If this is @code{#f}, then the service type denotes services that cannot
9725 be extended---i.e., services that do not receive ``values'' from other
9728 Otherwise, it must be a one-argument procedure. The procedure is called
9729 by @code{fold-services} and is passed a list of values collected from
9730 extensions. It must return a value that is a valid parameter value for
9731 the service instance.
9733 @item @code{extend} (default: @code{#f})
9734 If this is @code{#f}, services of this type cannot be extended.
9736 Otherwise, it must be a two-argument procedure: @code{fold-services}
9737 calls it, passing it the service's initial value as the first argument
9738 and the result of applying @code{compose} to the extension values as the
9742 @xref{Service Types and Services}, for examples.
9745 @deffn {Scheme Procedure} service-extension @var{target-type} @
9747 Return a new extension for services of type @var{target-type}.
9748 @var{compute} must be a one-argument procedure: @code{fold-services}
9749 calls it, passing it the value associated with the service that provides
9750 the extension; it must return a valid value for the target service.
9753 @deffn {Scheme Procedure} service-extension? @var{obj}
9754 Return true if @var{obj} is a service extension.
9757 At the core of the service abstraction lies the @code{fold-services}
9758 procedure, which is responsible for ``compiling'' a list of services
9759 down to a single directory that contains everything needed to boot and
9760 run the system---the directory shown by the @command{guix system build}
9761 command (@pxref{Invoking guix system}). In essence, it propagates
9762 service extensions down the service graph, updating each node parameters
9763 on the way, until it reaches the root node.
9765 @deffn {Scheme Procedure} fold-services @var{services} @
9766 [#:target-type @var{system-service-type}]
9767 Fold @var{services} by propagating their extensions down to the root of
9768 type @var{target-type}; return the root service adjusted accordingly.
9771 Lastly, the @code{(gnu services)} module also defines several essential
9772 service types, some of which are listed below.
9774 @defvr {Scheme Variable} system-service-type
9775 This is the root of the service graph. It produces the system directory
9776 as returned by the @command{guix system build} command.
9779 @defvr {Scheme Variable} boot-service-type
9780 The type of the ``boot service'', which produces the @dfn{boot script}.
9781 The boot script is what the initial RAM disk runs when booting.
9784 @defvr {Scheme Variable} etc-service-type
9785 The type of the @file{/etc} service. This service can be extended by
9786 passing it name/file tuples such as:
9789 (list `("issue" ,(plain-file "issue" "Welcome!\n")))
9792 In this example, the effect would be to add an @file{/etc/issue} file
9793 pointing to the given file.
9796 @defvr {Scheme Variable} setuid-program-service-type
9797 Type for the ``setuid-program service''. This service collects lists of
9798 executable file names, passed as gexps, and adds them to the set of
9799 setuid-root programs on the system (@pxref{Setuid Programs}).
9802 @defvr {Scheme Variable} profile-service-type
9803 Type of the service that populates the @dfn{system profile}---i.e., the
9804 programs under @file{/run/current-system/profile}. Other services can
9805 extend it by passing it lists of packages to add to the system profile.
9809 @node Shepherd Services
9810 @subsubsection Shepherd Services
9814 The @code{(gnu services shepherd)} provides a way to define services
9815 managed by the GNU@tie{}Shepherd, which is GuixSD initialization
9816 system---the first process that is started when the system boots,
9817 aka. PID@tie{}1 (@pxref{Introduction,,, shepherd, The GNU Shepherd
9820 Services in the Shepherd can depend on each other. For instance, the
9821 SSH daemon may need to be started after the syslog daemon has been
9822 started, which in turn can only happen once all the file systems have
9823 been mounted. The simple operating system defined earlier (@pxref{Using
9824 the Configuration System}) results in a service graph like this:
9826 @image{images/shepherd-graph,,5in,Typical shepherd service graph.}
9828 You can actually generate such a graph for any operating system
9829 definition using the @command{guix system shepherd-graph} command
9830 (@pxref{system-shepherd-graph, @command{guix system shepherd-graph}}).
9832 The @var{%shepherd-root-service} is a service object representing
9833 PID@tie{}1, of type @var{shepherd-root-service-type}; it can be extended
9834 by passing it lists of @code{<shepherd-service>} objects.
9836 @deftp {Data Type} shepherd-service
9837 The data type representing a service managed by the Shepherd.
9840 @item @code{provision}
9841 This is a list of symbols denoting what the service provides.
9843 These are the names that may be passed to @command{herd start},
9844 @command{herd status}, and similar commands (@pxref{Invoking herd,,,
9845 shepherd, The GNU Shepherd Manual}). @xref{Slots of services, the
9846 @code{provides} slot,, shepherd, The GNU Shepherd Manual}, for details.
9848 @item @code{requirements} (default: @code{'()})
9849 List of symbols denoting the Shepherd services this one depends on.
9851 @item @code{respawn?} (default: @code{#t})
9852 Whether to restart the service when it stops, for instance when the
9853 underlying process dies.
9856 @itemx @code{stop} (default: @code{#~(const #f)})
9857 The @code{start} and @code{stop} fields refer to the Shepherd's
9858 facilities to start and stop processes (@pxref{Service De- and
9859 Constructors,,, shepherd, The GNU Shepherd Manual}). They are given as
9860 G-expressions that get expanded in the Shepherd configuration file
9861 (@pxref{G-Expressions}).
9863 @item @code{documentation}
9864 A documentation string, as shown when running:
9867 herd doc @var{service-name}
9870 where @var{service-name} is one of the symbols in @var{provision}
9871 (@pxref{Invoking herd,,, shepherd, The GNU Shepherd Manual}).
9873 @item @code{modules} (default: @var{%default-modules})
9874 This is the list of modules that must be in scope when @code{start} and
9875 @code{stop} are evaluated.
9877 @item @code{imported-modules} (default: @var{%default-imported-modules})
9878 This is the list of modules to import in the execution environment of
9884 @defvr {Scheme Variable} shepherd-root-service-type
9885 The service type for the Shepherd ``root service''---i.e., PID@tie{}1.
9887 This is the service type that extensions target when they want to create
9888 shepherd services (@pxref{Service Types and Services}, for an example).
9889 Each extension must pass a list of @code{<shepherd-service>}.
9892 @defvr {Scheme Variable} %shepherd-root-service
9893 This service represents PID@tie{}1.
9897 @node Installing Debugging Files
9898 @section Installing Debugging Files
9900 @cindex debugging files
9901 Program binaries, as produced by the GCC compilers for instance, are
9902 typically written in the ELF format, with a section containing
9903 @dfn{debugging information}. Debugging information is what allows the
9904 debugger, GDB, to map binary code to source code; it is required to
9905 debug a compiled program in good conditions.
9907 The problem with debugging information is that is takes up a fair amount
9908 of disk space. For example, debugging information for the GNU C Library
9909 weighs in at more than 60 MiB. Thus, as a user, keeping all the
9910 debugging info of all the installed programs is usually not an option.
9911 Yet, space savings should not come at the cost of an impediment to
9912 debugging---especially in the GNU system, which should make it easier
9913 for users to exert their computing freedom (@pxref{GNU Distribution}).
9915 Thankfully, the GNU Binary Utilities (Binutils) and GDB provide a
9916 mechanism that allows users to get the best of both worlds: debugging
9917 information can be stripped from the binaries and stored in separate
9918 files. GDB is then able to load debugging information from those files,
9919 when they are available (@pxref{Separate Debug Files,,, gdb, Debugging
9922 The GNU distribution takes advantage of this by storing debugging
9923 information in the @code{lib/debug} sub-directory of a separate package
9924 output unimaginatively called @code{debug} (@pxref{Packages with
9925 Multiple Outputs}). Users can choose to install the @code{debug} output
9926 of a package when they need it. For instance, the following command
9927 installs the debugging information for the GNU C Library and for GNU
9931 guix package -i glibc:debug guile:debug
9934 GDB must then be told to look for debug files in the user's profile, by
9935 setting the @code{debug-file-directory} variable (consider setting it
9936 from the @file{~/.gdbinit} file, @pxref{Startup,,, gdb, Debugging with
9940 (gdb) set debug-file-directory ~/.guix-profile/lib/debug
9943 From there on, GDB will pick up debugging information from the
9944 @code{.debug} files under @file{~/.guix-profile/lib/debug}.
9946 In addition, you will most likely want GDB to be able to show the source
9947 code being debugged. To do that, you will have to unpack the source
9948 code of the package of interest (obtained with @code{guix build
9949 --source}, @pxref{Invoking guix build}), and to point GDB to that source
9950 directory using the @code{directory} command (@pxref{Source Path,
9951 @code{directory},, gdb, Debugging with GDB}).
9953 @c XXX: keep me up-to-date
9954 The @code{debug} output mechanism in Guix is implemented by the
9955 @code{gnu-build-system} (@pxref{Build Systems}). Currently, it is
9956 opt-in---debugging information is available only for those packages
9957 whose definition explicitly declares a @code{debug} output. This may be
9958 changed to opt-out in the future, if our build farm servers can handle
9959 the load. To check whether a package has a @code{debug} output, use
9960 @command{guix package --list-available} (@pxref{Invoking guix package}).
9963 @node Security Updates
9964 @section Security Updates
9967 As of version @value{VERSION}, the feature described in this section is
9971 @cindex security updates
9972 Occasionally, important security vulnerabilities are discovered in core
9973 software packages and must be patched. Guix follows a functional
9974 package management discipline (@pxref{Introduction}), which implies
9975 that, when a package is changed, @emph{every package that depends on it}
9976 must be rebuilt. This can significantly slow down the deployment of
9977 fixes in core packages such as libc or Bash, since basically the whole
9978 distribution would need to be rebuilt. Using pre-built binaries helps
9979 (@pxref{Substitutes}), but deployment may still take more time than
9983 To address that, Guix implements @dfn{grafts}, a mechanism that allows
9984 for fast deployment of critical updates without the costs associated
9985 with a whole-distribution rebuild. The idea is to rebuild only the
9986 package that needs to be patched, and then to ``graft'' it onto packages
9987 explicitly installed by the user and that were previously referring to
9988 the original package. The cost of grafting is typically very low, and
9989 order of magnitudes lower than a full rebuild of the dependency chain.
9991 @cindex replacements of packages, for grafts
9992 For instance, suppose a security update needs to be applied to Bash.
9993 Guix developers will provide a package definition for the ``fixed''
9994 Bash, say @var{bash-fixed}, in the usual way (@pxref{Defining
9995 Packages}). Then, the original package definition is augmented with a
9996 @code{replacement} field pointing to the package containing the bug fix:
10003 (replacement bash-fixed)))
10006 From there on, any package depending directly or indirectly on Bash that
10007 is installed will automatically be ``rewritten'' to refer to
10008 @var{bash-fixed} instead of @var{bash}. This grafting process takes
10009 time proportional to the size of the package, but expect less than a
10010 minute for an ``average'' package on a recent machine.
10012 Currently, the graft and the package it replaces (@var{bash-fixed} and
10013 @var{bash} in the example above) must have the exact same @code{name}
10014 and @code{version} fields. This restriction mostly comes from the fact
10015 that grafting works by patching files, including binary files, directly.
10016 Other restrictions may apply: for instance, when adding a graft to a
10017 package providing a shared library, the original shared library and its
10018 replacement must have the same @code{SONAME} and be binary-compatible.
10021 @node Package Modules
10022 @section Package Modules
10024 From a programming viewpoint, the package definitions of the
10025 GNU distribution are provided by Guile modules in the @code{(gnu packages
10026 @dots{})} name space@footnote{Note that packages under the @code{(gnu
10027 packages @dots{})} module name space are not necessarily ``GNU
10028 packages''. This module naming scheme follows the usual Guile module
10029 naming convention: @code{gnu} means that these modules are distributed
10030 as part of the GNU system, and @code{packages} identifies modules that
10031 define packages.} (@pxref{Modules, Guile modules,, guile, GNU Guile
10032 Reference Manual}). For instance, the @code{(gnu packages emacs)}
10033 module exports a variable named @code{emacs}, which is bound to a
10034 @code{<package>} object (@pxref{Defining Packages}).
10036 The @code{(gnu packages @dots{})} module name space is
10037 automatically scanned for packages by the command-line tools. For
10038 instance, when running @code{guix package -i emacs}, all the @code{(gnu
10039 packages @dots{})} modules are scanned until one that exports a package
10040 object whose name is @code{emacs} is found. This package search
10041 facility is implemented in the @code{(gnu packages)} module.
10043 @cindex customization, of packages
10044 @cindex package module search path
10045 Users can store package definitions in modules with different
10046 names---e.g., @code{(my-packages emacs)}@footnote{Note that the file
10047 name and module name must match. For instance, the @code{(my-packages
10048 emacs)} module must be stored in a @file{my-packages/emacs.scm} file
10049 relative to the load path specified with @option{--load-path} or
10050 @code{GUIX_PACKAGE_PATH}. @xref{Modules and the File System,,,
10051 guile, GNU Guile Reference Manual}, for details.}. These package definitions
10052 will not be visible by default. Thus, users can invoke commands such as
10053 @command{guix package} and @command{guix build} have to be used with the
10054 @code{-e} option so that they know where to find the package. Better
10055 yet, they can use the
10056 @code{-L} option of these commands to make those modules visible
10057 (@pxref{Invoking guix build, @code{--load-path}}), or define the
10058 @code{GUIX_PACKAGE_PATH} environment variable. This environment
10059 variable makes it easy to extend or customize the distribution and is
10060 honored by all the user interfaces.
10062 @defvr {Environment Variable} GUIX_PACKAGE_PATH
10063 This is a colon-separated list of directories to search for package
10064 modules. Directories listed in this variable take precedence over the
10065 distribution's own modules.
10068 The distribution is fully @dfn{bootstrapped} and @dfn{self-contained}:
10069 each package is built based solely on other packages in the
10070 distribution. The root of this dependency graph is a small set of
10071 @dfn{bootstrap binaries}, provided by the @code{(gnu packages
10072 bootstrap)} module. For more information on bootstrapping,
10073 @pxref{Bootstrapping}.
10075 @node Packaging Guidelines
10076 @section Packaging Guidelines
10078 The GNU distribution is nascent and may well lack some of your favorite
10079 packages. This section describes how you can help make the distribution
10080 grow. @xref{Contributing}, for additional information on how you can
10083 Free software packages are usually distributed in the form of
10084 @dfn{source code tarballs}---typically @file{tar.gz} files that contain
10085 all the source files. Adding a package to the distribution means
10086 essentially two things: adding a @dfn{recipe} that describes how to
10087 build the package, including a list of other packages required to build
10088 it, and adding @dfn{package meta-data} along with that recipe, such as a
10089 description and licensing information.
10091 In Guix all this information is embodied in @dfn{package definitions}.
10092 Package definitions provide a high-level view of the package. They are
10093 written using the syntax of the Scheme programming language; in fact,
10094 for each package we define a variable bound to the package definition,
10095 and export that variable from a module (@pxref{Package Modules}).
10096 However, in-depth Scheme knowledge is @emph{not} a prerequisite for
10097 creating packages. For more information on package definitions,
10098 @pxref{Defining Packages}.
10100 Once a package definition is in place, stored in a file in the Guix
10101 source tree, it can be tested using the @command{guix build} command
10102 (@pxref{Invoking guix build}). For example, assuming the new package is
10103 called @code{gnew}, you may run this command from the Guix build tree
10104 (@pxref{Running Guix Before It Is Installed}):
10107 ./pre-inst-env guix build gnew --keep-failed
10110 Using @code{--keep-failed} makes it easier to debug build failures since
10111 it provides access to the failed build tree. Another useful
10112 command-line option when debugging is @code{--log-file}, to access the
10115 If the package is unknown to the @command{guix} command, it may be that
10116 the source file contains a syntax error, or lacks a @code{define-public}
10117 clause to export the package variable. To figure it out, you may load
10118 the module from Guile to get more information about the actual error:
10121 ./pre-inst-env guile -c '(use-modules (gnu packages gnew))'
10124 Once your package builds correctly, please send us a patch
10125 (@pxref{Contributing}). Well, if you need help, we will be happy to
10126 help you too. Once the patch is committed in the Guix repository, the
10127 new package automatically gets built on the supported platforms by
10128 @url{http://hydra.gnu.org/jobset/gnu/master, our continuous integration
10131 @cindex substituter
10132 Users can obtain the new package definition simply by running
10133 @command{guix pull} (@pxref{Invoking guix pull}). When
10134 @code{hydra.gnu.org} is done building the package, installing the
10135 package automatically downloads binaries from there
10136 (@pxref{Substitutes}). The only place where human intervention is
10137 needed is to review and apply the patch.
10141 * Software Freedom:: What may go into the distribution.
10142 * Package Naming:: What's in a name?
10143 * Version Numbers:: When the name is not enough.
10144 * Synopses and Descriptions:: Helping users find the right package.
10145 * Python Modules:: Taming the snake.
10146 * Perl Modules:: Little pearls.
10147 * Fonts:: Fond of fonts.
10150 @node Software Freedom
10151 @subsection Software Freedom
10153 @c Adapted from http://www.gnu.org/philosophy/philosophy.html.
10155 The GNU operating system has been developed so that users can have
10156 freedom in their computing. GNU is @dfn{free software}, meaning that
10157 users have the @url{http://www.gnu.org/philosophy/free-sw.html,four
10158 essential freedoms}: to run the program, to study and change the program
10159 in source code form, to redistribute exact copies, and to distribute
10160 modified versions. Packages found in the GNU distribution provide only
10161 software that conveys these four freedoms.
10163 In addition, the GNU distribution follow the
10164 @url{http://www.gnu.org/distros/free-system-distribution-guidelines.html,free
10165 software distribution guidelines}. Among other things, these guidelines
10166 reject non-free firmware, recommendations of non-free software, and
10167 discuss ways to deal with trademarks and patents.
10169 Some packages contain a small and optional subset that violates the
10170 above guidelines, for instance because this subset is itself non-free
10171 code. When that happens, the offending items are removed with
10172 appropriate patches or code snippets in the package definition's
10173 @code{origin} form (@pxref{Defining Packages}). That way, @code{guix
10174 build --source} returns the ``freed'' source rather than the unmodified
10178 @node Package Naming
10179 @subsection Package Naming
10181 A package has actually two names associated with it:
10182 First, there is the name of the @emph{Scheme variable}, the one following
10183 @code{define-public}. By this name, the package can be made known in the
10184 Scheme code, for instance as input to another package. Second, there is
10185 the string in the @code{name} field of a package definition. This name
10186 is used by package management commands such as
10187 @command{guix package} and @command{guix build}.
10189 Both are usually the same and correspond to the lowercase conversion of
10190 the project name chosen upstream, with underscores replaced with
10191 hyphens. For instance, GNUnet is available as @code{gnunet}, and
10192 SDL_net as @code{sdl-net}.
10194 We do not add @code{lib} prefixes for library packages, unless these are
10195 already part of the official project name. But @pxref{Python
10196 Modules} and @ref{Perl Modules} for special rules concerning modules for
10197 the Python and Perl languages.
10199 Font package names are handled differently, @pxref{Fonts}.
10202 @node Version Numbers
10203 @subsection Version Numbers
10205 We usually package only the latest version of a given free software
10206 project. But sometimes, for instance for incompatible library versions,
10207 two (or more) versions of the same package are needed. These require
10208 different Scheme variable names. We use the name as defined
10209 in @ref{Package Naming}
10210 for the most recent version; previous versions use the same name, suffixed
10211 by @code{-} and the smallest prefix of the version number that may
10212 distinguish the two versions.
10214 The name inside the package definition is the same for all versions of a
10215 package and does not contain any version number.
10217 For instance, the versions 2.24.20 and 3.9.12 of GTK+ may be packaged as follows:
10220 (define-public gtk+
10225 (define-public gtk+-2
10228 (version "2.24.20")
10231 If we also wanted GTK+ 3.8.2, this would be packaged as
10233 (define-public gtk+-3.8
10240 @c See <https://lists.gnu.org/archive/html/guix-devel/2016-01/msg00425.html>,
10241 @c for a discussion of what follows.
10242 @cindex version number, for VCS snapshots
10243 Occasionally, we package snapshots of upstream's version control system
10244 (VCS) instead of formal releases. This should remain exceptional,
10245 because it is up to upstream developers to clarify what the stable
10246 release is. Yet, it is sometimes necessary. So, what should we put in
10247 the @code{version} field?
10249 Clearly, we need to make the commit identifier of the VCS snapshot
10250 visible in the version string, but we also need to make sure that the
10251 version string is monotonically increasing so that @command{guix package
10252 --upgrade} can determine which version is newer. Since commit
10253 identifiers, notably with Git, are not monotonically increasing, we add
10254 a revision number that we increase each time we upgrade to a newer
10255 snapshot. The resulting version string looks like this:
10260 | | `-- upstream commit ID
10262 | `--- Guix package revision
10264 latest upstream version
10267 It is a good idea to strip commit identifiers in the @code{version}
10268 field to, say, 7 digits. It avoids an aesthetic annoyance (assuming
10269 aesthetics have a role to play here) as well as problems related to OS
10270 limits such as the maximum shebang length (127 bytes for the Linux
10271 kernel.) It is best to use the full commit identifiers in
10272 @code{origin}s, though, to avoid ambiguities.
10274 @node Synopses and Descriptions
10275 @subsection Synopses and Descriptions
10277 As we have seen before, each package in GNU@tie{}Guix includes a
10278 synopsis and a description (@pxref{Defining Packages}). Synopses and
10279 descriptions are important: They are what @command{guix package
10280 --search} searches, and a crucial piece of information to help users
10281 determine whether a given package suits their needs. Consequently,
10282 packagers should pay attention to what goes into them.
10284 Synopses must start with a capital letter and must not end with a
10285 period. They must not start with ``a'' or ``the'', which usually does
10286 not bring anything; for instance, prefer ``File-frobbing tool'' over ``A
10287 tool that frobs files''. The synopsis should say what the package
10288 is---e.g., ``Core GNU utilities (file, text, shell)''---or what it is
10289 used for---e.g., the synopsis for GNU@tie{}grep is ``Print lines
10290 matching a pattern''.
10292 Keep in mind that the synopsis must be meaningful for a very wide
10293 audience. For example, ``Manipulate alignments in the SAM format''
10294 might make sense for a seasoned bioinformatics researcher, but might be
10295 fairly unhelpful or even misleading to a non-specialized audience. It
10296 is a good idea to come up with a synopsis that gives an idea of the
10297 application domain of the package. In this example, this might give
10298 something like ``Manipulate nucleotide sequence alignments'', which
10299 hopefully gives the user a better idea of whether this is what they are
10302 @cindex Texinfo markup, in package descriptions
10303 Descriptions should take between five and ten lines. Use full
10304 sentences, and avoid using acronyms without first introducing them.
10305 Descriptions can include Texinfo markup, which is useful to introduce
10306 ornaments such as @code{@@code} or @code{@@dfn}, bullet lists, or
10307 hyperlinks (@pxref{Overview,,, texinfo, GNU Texinfo}). However you
10308 should be careful when using some characters for example @samp{@@} and
10309 curly braces which are the basic special characters in Texinfo
10310 (@pxref{Special Characters,,, texinfo, GNU Texinfo}). User interfaces
10311 such as @command{guix package --show} take care of rendering it
10314 Synopses and descriptions are translated by volunteers
10315 @uref{http://translationproject.org/domain/guix-packages.html, at the
10316 Translation Project} so that as many users as possible can read them in
10317 their native language. User interfaces search them and display them in
10318 the language specified by the current locale.
10320 Translation is a lot of work so, as a packager, please pay even more
10321 attention to your synopses and descriptions as every change may entail
10322 additional work for translators. In order to help them, it is possible
10323 to make recommendations or instructions visible to them by inserting
10324 special comments like this (@pxref{xgettext Invocation,,, gettext, GNU
10328 ;; TRANSLATORS: "X11 resize-and-rotate" should not be translated.
10329 (description "ARandR is designed to provide a simple visual front end
10330 for the X11 resize-and-rotate (RandR) extension. @dots{}")
10334 @node Python Modules
10335 @subsection Python Modules
10337 We currently package Python 2 and Python 3, under the Scheme variable names
10338 @code{python-2} and @code{python} as explained in @ref{Version Numbers}.
10339 To avoid confusion and naming clashes with other programming languages, it
10340 seems desirable that the name of a package for a Python module contains
10341 the word @code{python}.
10343 Some modules are compatible with only one version of Python, others with both.
10344 If the package Foo compiles only with Python 3, we name it
10345 @code{python-foo}; if it compiles only with Python 2, we name it
10346 @code{python2-foo}. If it is compatible with both versions, we create two
10347 packages with the corresponding names.
10349 If a project already contains the word @code{python}, we drop this;
10350 for instance, the module python-dateutil is packaged under the names
10351 @code{python-dateutil} and @code{python2-dateutil}.
10355 @subsection Perl Modules
10357 Perl programs standing for themselves are named as any other package,
10358 using the lowercase upstream name.
10359 For Perl packages containing a single class, we use the lowercase class name,
10360 replace all occurrences of @code{::} by dashes and prepend the prefix
10362 So the class @code{XML::Parser} becomes @code{perl-xml-parser}.
10363 Modules containing several classes keep their lowercase upstream name and
10364 are also prepended by @code{perl-}. Such modules tend to have the word
10365 @code{perl} somewhere in their name, which gets dropped in favor of the
10366 prefix. For instance, @code{libwww-perl} becomes @code{perl-libwww}.
10372 For fonts that are in general not installed by a user for typesetting
10373 purposes, or that are distributed as part of a larger software package,
10374 we rely on the general packaging rules for software; for instance, this
10375 applies to the fonts delivered as part of the X.Org system or fonts that
10376 are part of TeX Live.
10378 To make it easier for a user to search for fonts, names for other packages
10379 containing only fonts are constructed as follows, independently of the
10380 upstream package name.
10382 The name of a package containing only one font family starts with
10383 @code{font-}; it is followed by the foundry name and a dash @code{-}
10384 if the foundry is known, and the font family name, in which spaces are
10385 replaced by dashes (and as usual, all upper case letters are transformed
10387 For example, the Gentium font family by SIL is packaged under the name
10388 @code{font-sil-gentium}.
10390 For a package containing several font families, the name of the collection
10391 is used in the place of the font family name.
10392 For instance, the Liberation fonts consist of three families,
10393 Liberation Sans, Liberation Serif and Liberation Mono.
10394 These could be packaged separately under the names
10395 @code{font-liberation-sans} and so on; but as they are distributed together
10396 under a common name, we prefer to package them together as
10397 @code{font-liberation}.
10399 In the case where several formats of the same font family or font collection
10400 are packaged separately, a short form of the format, prepended by a dash,
10401 is added to the package name. We use @code{-ttf} for TrueType fonts,
10402 @code{-otf} for OpenType fonts and @code{-type1} for PostScript Type 1
10407 @node Bootstrapping
10408 @section Bootstrapping
10410 @c Adapted from the ELS 2013 paper.
10412 @cindex bootstrapping
10414 Bootstrapping in our context refers to how the distribution gets built
10415 ``from nothing''. Remember that the build environment of a derivation
10416 contains nothing but its declared inputs (@pxref{Introduction}). So
10417 there's an obvious chicken-and-egg problem: how does the first package
10418 get built? How does the first compiler get compiled? Note that this is
10419 a question of interest only to the curious hacker, not to the regular
10420 user, so you can shamelessly skip this section if you consider yourself
10421 a ``regular user''.
10423 @cindex bootstrap binaries
10424 The GNU system is primarily made of C code, with libc at its core. The
10425 GNU build system itself assumes the availability of a Bourne shell and
10426 command-line tools provided by GNU Coreutils, Awk, Findutils, `sed', and
10427 `grep'. Furthermore, build programs---programs that run
10428 @code{./configure}, @code{make}, etc.---are written in Guile Scheme
10429 (@pxref{Derivations}). Consequently, to be able to build anything at
10430 all, from scratch, Guix relies on pre-built binaries of Guile, GCC,
10431 Binutils, libc, and the other packages mentioned above---the
10432 @dfn{bootstrap binaries}.
10434 These bootstrap binaries are ``taken for granted'', though we can also
10435 re-create them if needed (more on that later).
10437 @unnumberedsubsec Preparing to Use the Bootstrap Binaries
10439 @c As of Emacs 24.3, Info-mode displays the image, but since it's a
10440 @c large image, it's hard to scroll. Oh well.
10441 @image{images/bootstrap-graph,6in,,Dependency graph of the early bootstrap derivations}
10443 The figure above shows the very beginning of the dependency graph of the
10444 distribution, corresponding to the package definitions of the @code{(gnu
10445 packages bootstrap)} module. A similar figure can be generated with
10446 @command{guix graph} (@pxref{Invoking guix graph}), along the lines of:
10449 guix graph -t derivation \
10450 -e '(@@@@ (gnu packages bootstrap) %bootstrap-gcc)' \
10454 At this level of detail, things are
10455 slightly complex. First, Guile itself consists of an ELF executable,
10456 along with many source and compiled Scheme files that are dynamically
10457 loaded when it runs. This gets stored in the @file{guile-2.0.7.tar.xz}
10458 tarball shown in this graph. This tarball is part of Guix's ``source''
10459 distribution, and gets inserted into the store with @code{add-to-store}
10460 (@pxref{The Store}).
10462 But how do we write a derivation that unpacks this tarball and adds it
10463 to the store? To solve this problem, the @code{guile-bootstrap-2.0.drv}
10464 derivation---the first one that gets built---uses @code{bash} as its
10465 builder, which runs @code{build-bootstrap-guile.sh}, which in turn calls
10466 @code{tar} to unpack the tarball. Thus, @file{bash}, @file{tar},
10467 @file{xz}, and @file{mkdir} are statically-linked binaries, also part of
10468 the Guix source distribution, whose sole purpose is to allow the Guile
10469 tarball to be unpacked.
10471 Once @code{guile-bootstrap-2.0.drv} is built, we have a functioning
10472 Guile that can be used to run subsequent build programs. Its first task
10473 is to download tarballs containing the other pre-built binaries---this
10474 is what the @code{.tar.xz.drv} derivations do. Guix modules such as
10475 @code{ftp-client.scm} are used for this purpose. The
10476 @code{module-import.drv} derivations import those modules in a directory
10477 in the store, using the original layout. The
10478 @code{module-import-compiled.drv} derivations compile those modules, and
10479 write them in an output directory with the right layout. This
10480 corresponds to the @code{#:modules} argument of
10481 @code{build-expression->derivation} (@pxref{Derivations}).
10483 Finally, the various tarballs are unpacked by the
10484 derivations @code{gcc-bootstrap-0.drv}, @code{glibc-bootstrap-0.drv},
10485 etc., at which point we have a working C tool chain.
10488 @unnumberedsubsec Building the Build Tools
10490 Bootstrapping is complete when we have a full tool chain that does not
10491 depend on the pre-built bootstrap tools discussed above. This
10492 no-dependency requirement is verified by checking whether the files of
10493 the final tool chain contain references to the @file{/gnu/store}
10494 directories of the bootstrap inputs. The process that leads to this
10495 ``final'' tool chain is described by the package definitions found in
10496 the @code{(gnu packages commencement)} module.
10498 The @command{guix graph} command allows us to ``zoom out'' compared to
10499 the graph above, by looking at the level of package objects instead of
10500 individual derivations---remember that a package may translate to
10501 several derivations, typically one derivation to download its source,
10502 one to build the Guile modules it needs, and one to actually build the
10503 package from source. The command:
10506 guix graph -t bag \
10507 -e '(@@@@ (gnu packages commencement)
10508 glibc-final-with-bootstrap-bash)' | dot -Tps > t.ps
10512 produces the dependency graph leading to the ``final'' C
10513 library@footnote{You may notice the @code{glibc-intermediate} label,
10514 suggesting that it is not @emph{quite} final, but as a good
10515 approximation, we will consider it final.}, depicted below.
10517 @image{images/bootstrap-packages,6in,,Dependency graph of the early packages}
10519 @c See <http://lists.gnu.org/archive/html/gnu-system-discuss/2012-10/msg00000.html>.
10520 The first tool that gets built with the bootstrap binaries is
10521 GNU@tie{}Make---noted @code{make-boot0} above---which is a prerequisite
10522 for all the following packages. From there Findutils and Diffutils get
10525 Then come the first-stage Binutils and GCC, built as pseudo cross
10526 tools---i.e., with @code{--target} equal to @code{--host}. They are
10527 used to build libc. Thanks to this cross-build trick, this libc is
10528 guaranteed not to hold any reference to the initial tool chain.
10530 From there the final Binutils and GCC (not shown above) are built.
10532 from the final Binutils, and links programs against the just-built libc.
10533 This tool chain is used to build the other packages used by Guix and by
10534 the GNU Build System: Guile, Bash, Coreutils, etc.
10536 And voilà! At this point we have the complete set of build tools that
10537 the GNU Build System expects. These are in the @code{%final-inputs}
10538 variable of the @code{(gnu packages commencement)} module, and are
10539 implicitly used by any package that uses @code{gnu-build-system}
10540 (@pxref{Build Systems, @code{gnu-build-system}}).
10543 @unnumberedsubsec Building the Bootstrap Binaries
10545 Because the final tool chain does not depend on the bootstrap binaries,
10546 those rarely need to be updated. Nevertheless, it is useful to have an
10547 automated way to produce them, should an update occur, and this is what
10548 the @code{(gnu packages make-bootstrap)} module provides.
10550 The following command builds the tarballs containing the bootstrap
10551 binaries (Guile, Binutils, GCC, libc, and a tarball containing a mixture
10552 of Coreutils and other basic command-line tools):
10555 guix build bootstrap-tarballs
10558 The generated tarballs are those that should be referred to in the
10559 @code{(gnu packages bootstrap)} module mentioned at the beginning of
10562 Still here? Then perhaps by now you've started to wonder: when do we
10563 reach a fixed point? That is an interesting question! The answer is
10564 unknown, but if you would like to investigate further (and have
10565 significant computational and storage resources to do so), then let us
10569 @section Porting to a New Platform
10571 As discussed above, the GNU distribution is self-contained, and
10572 self-containment is achieved by relying on pre-built ``bootstrap
10573 binaries'' (@pxref{Bootstrapping}). These binaries are specific to an
10574 operating system kernel, CPU architecture, and application binary
10575 interface (ABI). Thus, to port the distribution to a platform that is
10576 not yet supported, one must build those bootstrap binaries, and update
10577 the @code{(gnu packages bootstrap)} module to use them on that platform.
10579 Fortunately, Guix can @emph{cross compile} those bootstrap binaries.
10580 When everything goes well, and assuming the GNU tool chain supports the
10581 target platform, this can be as simple as running a command like this
10585 guix build --target=armv5tel-linux-gnueabi bootstrap-tarballs
10588 For this to work, the @code{glibc-dynamic-linker} procedure in
10589 @code{(gnu packages bootstrap)} must be augmented to return the right
10590 file name for libc's dynamic linker on that platform; likewise,
10591 @code{system->linux-architecture} in @code{(gnu packages linux)} must be
10592 taught about the new platform.
10594 Once these are built, the @code{(gnu packages bootstrap)} module needs
10595 to be updated to refer to these binaries on the target platform. That
10596 is, the hashes and URLs of the bootstrap tarballs for the new platform
10597 must be added alongside those of the currently supported platforms. The
10598 bootstrap Guile tarball is treated specially: it is expected to be
10599 available locally, and @file{gnu-system.am} has rules do download it for
10600 the supported architectures; a rule for the new platform must be added
10603 In practice, there may be some complications. First, it may be that the
10604 extended GNU triplet that specifies an ABI (like the @code{eabi} suffix
10605 above) is not recognized by all the GNU tools. Typically, glibc
10606 recognizes some of these, whereas GCC uses an extra @code{--with-abi}
10607 configure flag (see @code{gcc.scm} for examples of how to handle this).
10608 Second, some of the required packages could fail to build for that
10609 platform. Lastly, the generated binaries could be broken for some
10612 @c *********************************************************************
10613 @include contributing.texi
10615 @c *********************************************************************
10616 @node Acknowledgments
10617 @chapter Acknowledgments
10619 Guix is based on the @uref{http://nixos.org/nix/, Nix package manager},
10620 which was designed and
10621 implemented by Eelco Dolstra, with contributions from other people (see
10622 the @file{nix/AUTHORS} file in Guix.) Nix pioneered functional package
10623 management, and promoted unprecedented features, such as transactional
10624 package upgrades and rollbacks, per-user profiles, and referentially
10625 transparent build processes. Without this work, Guix would not exist.
10627 The Nix-based software distributions, Nixpkgs and NixOS, have also been
10628 an inspiration for Guix.
10630 GNU@tie{}Guix itself is a collective work with contributions from a
10631 number of people. See the @file{AUTHORS} file in Guix for more
10632 information on these fine people. The @file{THANKS} file lists people
10633 who have helped by reporting bugs, taking care of the infrastructure,
10634 providing artwork and themes, making suggestions, and more---thank you!
10637 @c *********************************************************************
10638 @node GNU Free Documentation License
10639 @appendix GNU Free Documentation License
10641 @include fdl-1.3.texi
10643 @c *********************************************************************
10644 @node Concept Index
10645 @unnumbered Concept Index
10648 @node Programming Index
10649 @unnumbered Programming Index
10650 @syncodeindex tp fn
10651 @syncodeindex vr fn
10656 @c Local Variables:
10657 @c ispell-local-dictionary: "american";