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
1646 Options}). It also support package transformation options, such as
1647 @option{--with-source} (@pxref{Package Transformation Options}).
1648 However, note that package transformations are lost when upgrading; to
1649 preserve transformation across upgrades, you should define your own
1650 package variant in a Guile module and add it to @code{GUIX_PACKAGE_PATH}
1651 (@pxref{Defining Packages}).
1655 @section Substitutes
1658 @cindex pre-built binaries
1659 Guix supports transparent source/binary deployment, which means that it
1660 can either build things locally, or download pre-built items from a
1661 server. We call these pre-built items @dfn{substitutes}---they are
1662 substitutes for local build results. In many cases, downloading a
1663 substitute is much faster than building things locally.
1665 Substitutes can be anything resulting from a derivation build
1666 (@pxref{Derivations}). Of course, in the common case, they are
1667 pre-built package binaries, but source tarballs, for instance, which
1668 also result from derivation builds, can be available as substitutes.
1670 The @code{hydra.gnu.org} server is a front-end to a build farm that
1671 builds packages from the GNU distribution continuously for some
1672 architectures, and makes them available as substitutes (@pxref{Emacs
1673 Hydra}, for information on how to query the continuous integration
1674 server). This is the
1675 default source of substitutes; it can be overridden by passing the
1676 @option{--substitute-urls} option either to @command{guix-daemon}
1677 (@pxref{daemon-substitute-urls,, @code{guix-daemon --substitute-urls}})
1678 or to client tools such as @command{guix package}
1679 (@pxref{client-substitute-urls,, client @option{--substitute-urls}
1683 @cindex digital signatures
1684 To allow Guix to download substitutes from @code{hydra.gnu.org}, you
1685 must add its public key to the access control list (ACL) of archive
1686 imports, using the @command{guix archive} command (@pxref{Invoking guix
1687 archive}). Doing so implies that you trust @code{hydra.gnu.org} to not
1688 be compromised and to serve genuine substitutes.
1690 This public key is installed along with Guix, in
1691 @code{@var{prefix}/share/guix/hydra.gnu.org.pub}, where @var{prefix} is
1692 the installation prefix of Guix. If you installed Guix from source,
1693 make sure you checked the GPG signature of
1694 @file{guix-@value{VERSION}.tar.gz}, which contains this public key file.
1695 Then, you can run something like this:
1698 # guix archive --authorize < hydra.gnu.org.pub
1701 Once this is in place, the output of a command like @code{guix build}
1702 should change from something like:
1705 $ guix build emacs --dry-run
1706 The following derivations would be built:
1707 /gnu/store/yr7bnx8xwcayd6j95r2clmkdl1qh688w-emacs-24.3.drv
1708 /gnu/store/x8qsh1hlhgjx6cwsjyvybnfv2i37z23w-dbus-1.6.4.tar.gz.drv
1709 /gnu/store/1ixwp12fl950d15h2cj11c73733jay0z-alsa-lib-1.0.27.1.tar.bz2.drv
1710 /gnu/store/nlma1pw0p603fpfiqy7kn4zm105r5dmw-util-linux-2.21.drv
1718 $ guix build emacs --dry-run
1719 The following files would be downloaded:
1720 /gnu/store/pk3n22lbq6ydamyymqkkz7i69wiwjiwi-emacs-24.3
1721 /gnu/store/2ygn4ncnhrpr61rssa6z0d9x22si0va3-libjpeg-8d
1722 /gnu/store/71yz6lgx4dazma9dwn2mcjxaah9w77jq-cairo-1.12.16
1723 /gnu/store/7zdhgp0n1518lvfn8mb96sxqfmvqrl7v-libxrender-0.9.7
1728 This indicates that substitutes from @code{hydra.gnu.org} are usable and
1729 will be downloaded, when possible, for future builds.
1731 Guix ignores substitutes that are not signed, or that are not signed by
1732 one of the keys listed in the ACL. It also detects and raises an error
1733 when attempting to use a substitute that has been tampered with.
1736 Substitutes are downloaded over HTTP. The @code{http_proxy} environment
1737 variable can be set in the environment of @command{guix-daemon} and is
1738 honored for downloads of substitutes. Note that the value of
1739 @code{http_proxy} in the environment where @command{guix build},
1740 @command{guix package}, and other client commands are run has
1741 @emph{absolutely no effect}.
1743 The substitute mechanism can be disabled globally by running
1744 @code{guix-daemon} with @code{--no-substitutes} (@pxref{Invoking
1745 guix-daemon}). It can also be disabled temporarily by passing the
1746 @code{--no-substitutes} option to @command{guix package}, @command{guix
1747 build}, and other command-line tools.
1750 Today, each individual's control over their own computing is at the
1751 mercy of institutions, corporations, and groups with enough power and
1752 determination to subvert the computing infrastructure and exploit its
1753 weaknesses. While using @code{hydra.gnu.org} substitutes can be
1754 convenient, we encourage users to also build on their own, or even run
1755 their own build farm, such that @code{hydra.gnu.org} is less of an
1756 interesting target. One way to help is by publishing the software you
1757 build using @command{guix publish} so that others have one more choice
1758 of server to download substitutes from (@pxref{Invoking guix publish}).
1760 Guix has the foundations to maximize build reproducibility
1761 (@pxref{Features}). In most cases, independent builds of a given
1762 package or derivation should yield bit-identical results. Thus, through
1763 a diverse set of independent package builds, we can strengthen the
1764 integrity of our systems. The @command{guix challenge} command aims to
1765 help users assess substitute servers, and to assist developers in
1766 finding out about non-deterministic package builds (@pxref{Invoking guix
1767 challenge}). Similarly, the @option{--check} option of @command{guix
1768 build} allows users to check whether previously-installed substitutes
1769 are genuine by rebuilding them locally (@pxref{build-check,
1770 @command{guix build --check}}).
1772 In the future, we want Guix to have support to publish and retrieve
1773 binaries to/from other users, in a peer-to-peer fashion. If you would
1774 like to discuss this project, join us on @email{guix-devel@@gnu.org}.
1777 @node Packages with Multiple Outputs
1778 @section Packages with Multiple Outputs
1780 @cindex multiple-output packages
1781 @cindex package outputs
1783 Often, packages defined in Guix have a single @dfn{output}---i.e., the
1784 source package leads exactly one directory in the store. When running
1785 @command{guix package -i glibc}, one installs the default output of the
1786 GNU libc package; the default output is called @code{out}, but its name
1787 can be omitted as shown in this command. In this particular case, the
1788 default output of @code{glibc} contains all the C header files, shared
1789 libraries, static libraries, Info documentation, and other supporting
1792 Sometimes it is more appropriate to separate the various types of files
1793 produced from a single source package into separate outputs. For
1794 instance, the GLib C library (used by GTK+ and related packages)
1795 installs more than 20 MiB of reference documentation as HTML pages.
1796 To save space for users who do not need it, the documentation goes to a
1797 separate output, called @code{doc}. To install the main GLib output,
1798 which contains everything but the documentation, one would run:
1801 guix package -i glib
1804 The command to install its documentation is:
1807 guix package -i glib:doc
1810 Some packages install programs with different ``dependency footprints''.
1811 For instance, the WordNet package install both command-line tools and
1812 graphical user interfaces (GUIs). The former depend solely on the C
1813 library, whereas the latter depend on Tcl/Tk and the underlying X
1814 libraries. In this case, we leave the command-line tools in the default
1815 output, whereas the GUIs are in a separate output. This allows users
1816 who do not need the GUIs to save space. The @command{guix size} command
1817 can help find out about such situations (@pxref{Invoking guix size}).
1818 @command{guix graph} can also be helpful (@pxref{Invoking guix graph}).
1820 There are several such multiple-output packages in the GNU distribution.
1821 Other conventional output names include @code{lib} for libraries and
1822 possibly header files, @code{bin} for stand-alone programs, and
1823 @code{debug} for debugging information (@pxref{Installing Debugging
1824 Files}). The outputs of a packages are listed in the third column of
1825 the output of @command{guix package --list-available} (@pxref{Invoking
1829 @node Invoking guix gc
1830 @section Invoking @command{guix gc}
1832 @cindex garbage collector
1833 Packages that are installed but not used may be @dfn{garbage-collected}.
1834 The @command{guix gc} command allows users to explicitly run the garbage
1835 collector to reclaim space from the @file{/gnu/store} directory. It is
1836 the @emph{only} way to remove files from @file{/gnu/store}---removing
1837 files or directories manually may break it beyond repair!
1839 The garbage collector has a set of known @dfn{roots}: any file under
1840 @file{/gnu/store} reachable from a root is considered @dfn{live} and
1841 cannot be deleted; any other file is considered @dfn{dead} and may be
1842 deleted. The set of garbage collector roots includes default user
1843 profiles, and may be augmented with @command{guix build --root}, for
1844 example (@pxref{Invoking guix build}).
1846 Prior to running @code{guix gc --collect-garbage} to make space, it is
1847 often useful to remove old generations from user profiles; that way, old
1848 package builds referenced by those generations can be reclaimed. This
1849 is achieved by running @code{guix package --delete-generations}
1850 (@pxref{Invoking guix package}).
1852 The @command{guix gc} command has three modes of operation: it can be
1853 used to garbage-collect any dead files (the default), to delete specific
1854 files (the @code{--delete} option), to print garbage-collector
1855 information, or for more advanced queries. The garbage collection
1856 options are as follows:
1859 @item --collect-garbage[=@var{min}]
1860 @itemx -C [@var{min}]
1861 Collect garbage---i.e., unreachable @file{/gnu/store} files and
1862 sub-directories. This is the default operation when no option is
1865 When @var{min} is given, stop once @var{min} bytes have been collected.
1866 @var{min} may be a number of bytes, or it may include a unit as a
1867 suffix, such as @code{MiB} for mebibytes and @code{GB} for gigabytes
1868 (@pxref{Block size, size specifications,, coreutils, GNU Coreutils}).
1870 When @var{min} is omitted, collect all the garbage.
1874 Attempt to delete all the store files and directories specified as
1875 arguments. This fails if some of the files are not in the store, or if
1876 they are still live.
1878 @item --list-failures
1879 List store items corresponding to cached build failures.
1881 This prints nothing unless the daemon was started with
1882 @option{--cache-failures} (@pxref{Invoking guix-daemon,
1883 @option{--cache-failures}}).
1885 @item --clear-failures
1886 Remove the specified store items from the failed-build cache.
1888 Again, this option only makes sense when the daemon is started with
1889 @option{--cache-failures}. Otherwise, it does nothing.
1892 Show the list of dead files and directories still present in the
1893 store---i.e., files and directories no longer reachable from any root.
1896 Show the list of live store files and directories.
1900 In addition, the references among existing store files can be queried:
1906 List the references (respectively, the referrers) of store files given
1912 List the requisites of the store files passed as arguments. Requisites
1913 include the store files themselves, their references, and the references
1914 of these, recursively. In other words, the returned list is the
1915 @dfn{transitive closure} of the store files.
1917 @xref{Invoking guix size}, for a tool to profile the size of an
1918 element's closure. @xref{Invoking guix graph}, for a tool to visualize
1919 the graph of references.
1923 Lastly, the following options allow you to check the integrity of the
1924 store and to control disk usage.
1928 @item --verify[=@var{options}]
1929 @cindex integrity, of the store
1930 @cindex integrity checking
1931 Verify the integrity of the store.
1933 By default, make sure that all the store items marked as valid in the
1934 daemon's database actually exist in @file{/gnu/store}.
1936 When provided, @var{options} must a comma-separated list containing one
1937 or more of @code{contents} and @code{repair}.
1939 When passing @option{--verify=contents}, the daemon will compute the
1940 content hash of each store item and compare it against its hash in the
1941 database. Hash mismatches are reported as data corruptions. Because it
1942 traverses @emph{all the files in the store}, this command can take a
1943 long time, especially on systems with a slow disk drive.
1945 @cindex repairing the store
1946 Using @option{--verify=repair} or @option{--verify=contents,repair}
1947 causes the daemon to try to repair corrupt store items by fetching
1948 substitutes for them (@pxref{Substitutes}). Because repairing is not
1949 atomic, and thus potentially dangerous, it is available only to the
1950 system administrator.
1953 @cindex deduplication
1954 Optimize the store by hard-linking identical files---this is
1955 @dfn{deduplication}.
1957 The daemon performs deduplication after each successful build or archive
1958 import, unless it was started with @code{--disable-deduplication}
1959 (@pxref{Invoking guix-daemon, @code{--disable-deduplication}}). Thus,
1960 this option is primarily useful when the daemon was running with
1961 @code{--disable-deduplication}.
1965 @node Invoking guix pull
1966 @section Invoking @command{guix pull}
1968 Packages are installed or upgraded to the latest version available in
1969 the distribution currently available on your local machine. To update
1970 that distribution, along with the Guix tools, you must run @command{guix
1971 pull}: the command downloads the latest Guix source code and package
1972 descriptions, and deploys it.
1974 On completion, @command{guix package} will use packages and package
1975 versions from this just-retrieved copy of Guix. Not only that, but all
1976 the Guix commands and Scheme modules will also be taken from that latest
1977 version. New @command{guix} sub-commands added by the update also
1978 become available@footnote{Under the hood, @command{guix pull} updates
1979 the @file{~/.config/guix/latest} symbolic link to point to the latest
1980 Guix, and the @command{guix} command loads code from there.}.
1982 The @command{guix pull} command is usually invoked with no arguments,
1983 but it supports the following options:
1987 Produce verbose output, writing build logs to the standard error output.
1989 @item --url=@var{url}
1990 Download the source tarball of Guix from @var{url}.
1992 By default, the tarball is taken from its canonical address at
1993 @code{gnu.org}, for the stable branch of Guix.
1996 Use the bootstrap Guile to build the latest Guix. This option is only
1997 useful to Guix developers.
2001 @node Invoking guix archive
2002 @section Invoking @command{guix archive}
2004 The @command{guix archive} command allows users to @dfn{export} files
2005 from the store into a single archive, and to later @dfn{import} them.
2006 In particular, it allows store files to be transferred from one machine
2007 to another machine's store. For example, to transfer the @code{emacs}
2008 package to a machine connected over SSH, one would run:
2011 guix archive --export -r emacs | ssh the-machine guix archive --import
2015 Similarly, a complete user profile may be transferred from one machine
2016 to another like this:
2019 guix archive --export -r $(readlink -f ~/.guix-profile) | \
2020 ssh the-machine guix-archive --import
2024 However, note that, in both examples, all of @code{emacs} and the
2025 profile as well as all of their dependencies are transferred (due to
2026 @code{-r}), regardless of what is already available in the target
2027 machine's store. The @code{--missing} option can help figure out which
2028 items are missing from the target's store.
2030 Archives are stored in the ``Nix archive'' or ``Nar'' format, which is
2031 comparable in spirit to `tar', but with a few noteworthy differences
2032 that make it more appropriate for our purposes. First, rather than
2033 recording all Unix meta-data for each file, the Nar format only mentions
2034 the file type (regular, directory, or symbolic link); Unix permissions
2035 and owner/group are dismissed. Second, the order in which directory
2036 entries are stored always follows the order of file names according to
2037 the C locale collation order. This makes archive production fully
2040 When exporting, the daemon digitally signs the contents of the archive,
2041 and that digital signature is appended. When importing, the daemon
2042 verifies the signature and rejects the import in case of an invalid
2043 signature or if the signing key is not authorized.
2044 @c FIXME: Add xref to daemon doc about signatures.
2046 The main options are:
2050 Export the specified store files or packages (see below.) Write the
2051 resulting archive to the standard output.
2053 Dependencies are @emph{not} included in the output, unless
2054 @code{--recursive} is passed.
2058 When combined with @code{--export}, this instructs @command{guix
2059 archive} to include dependencies of the given items in the archive.
2060 Thus, the resulting archive is self-contained: it contains the closure
2061 of the exported store items.
2064 Read an archive from the standard input, and import the files listed
2065 therein into the store. Abort if the archive has an invalid digital
2066 signature, or if it is signed by a public key not among the authorized
2067 keys (see @code{--authorize} below.)
2070 Read a list of store file names from the standard input, one per line,
2071 and write on the standard output the subset of these files missing from
2074 @item --generate-key[=@var{parameters}]
2075 @cindex signing, archives
2076 Generate a new key pair for the daemons. This is a prerequisite before
2077 archives can be exported with @code{--export}. Note that this operation
2078 usually takes time, because it needs to gather enough entropy to
2079 generate the key pair.
2081 The generated key pair is typically stored under @file{/etc/guix}, in
2082 @file{signing-key.pub} (public key) and @file{signing-key.sec} (private
2083 key, which must be kept secret.) When @var{parameters} is omitted,
2084 an ECDSA key using the Ed25519 curve is generated, or, for Libgcrypt
2085 versions before 1.6.0, it is a 4096-bit RSA key.
2086 Alternately, @var{parameters} can specify
2087 @code{genkey} parameters suitable for Libgcrypt (@pxref{General
2088 public-key related Functions, @code{gcry_pk_genkey},, gcrypt, The
2089 Libgcrypt Reference Manual}).
2092 @cindex authorizing, archives
2093 Authorize imports signed by the public key passed on standard input.
2094 The public key must be in ``s-expression advanced format''---i.e., the
2095 same format as the @file{signing-key.pub} file.
2097 The list of authorized keys is kept in the human-editable file
2098 @file{/etc/guix/acl}. The file contains
2099 @url{http://people.csail.mit.edu/rivest/Sexp.txt, ``advanced-format
2100 s-expressions''} and is structured as an access-control list in the
2101 @url{http://theworld.com/~cme/spki.txt, Simple Public-Key Infrastructure
2104 @item --extract=@var{directory}
2105 @itemx -x @var{directory}
2106 Read a single-item archive as served by substitute servers
2107 (@pxref{Substitutes}) and extract it to @var{directory}. This is a
2108 low-level operation needed in only very narrow use cases; see below.
2110 For example, the following command extracts the substitute for Emacs
2111 served by @code{hydra.gnu.org} to @file{/tmp/emacs}:
2115 http://hydra.gnu.org/nar/@dots{}-emacs-24.5 \
2116 | bunzip2 | guix archive -x /tmp/emacs
2119 Single-item archives are different from multiple-item archives produced
2120 by @command{guix archive --export}; they contain a single store item,
2121 and they do @emph{not} embed a signature. Thus this operation does
2122 @emph{no} signature verification and its output should be considered
2125 The primary purpose of this operation is to facilitate inspection of
2126 archive contents coming from possibly untrusted substitute servers.
2130 To export store files as an archive to the standard output, run:
2133 guix archive --export @var{options} @var{specifications}...
2136 @var{specifications} may be either store file names or package
2137 specifications, as for @command{guix package} (@pxref{Invoking guix
2138 package}). For instance, the following command creates an archive
2139 containing the @code{gui} output of the @code{git} package and the main
2140 output of @code{emacs}:
2143 guix archive --export git:gui /gnu/store/...-emacs-24.3 > great.nar
2146 If the specified packages are not built yet, @command{guix archive}
2147 automatically builds them. The build process may be controlled with the
2148 common build options (@pxref{Common Build Options}).
2150 @c *********************************************************************
2153 @c *********************************************************************
2154 @node Programming Interface
2155 @chapter Programming Interface
2157 GNU Guix provides several Scheme programming interfaces (APIs) to
2158 define, build, and query packages. The first interface allows users to
2159 write high-level package definitions. These definitions refer to
2160 familiar packaging concepts, such as the name and version of a package,
2161 its build system, and its dependencies. These definitions can then be
2162 turned into concrete build actions.
2164 Build actions are performed by the Guix daemon, on behalf of users. In a
2165 standard setup, the daemon has write access to the store---the
2166 @file{/gnu/store} directory---whereas users do not. The recommended
2167 setup also has the daemon perform builds in chroots, under a specific
2168 build users, to minimize interference with the rest of the system.
2171 Lower-level APIs are available to interact with the daemon and the
2172 store. To instruct the daemon to perform a build action, users actually
2173 provide it with a @dfn{derivation}. A derivation is a low-level
2174 representation of the build actions to be taken, and the environment in
2175 which they should occur---derivations are to package definitions what
2176 assembly is to C programs. The term ``derivation'' comes from the fact
2177 that build results @emph{derive} from them.
2179 This chapter describes all these APIs in turn, starting from high-level
2180 package definitions.
2183 * Defining Packages:: Defining new packages.
2184 * Build Systems:: Specifying how packages are built.
2185 * The Store:: Manipulating the package store.
2186 * Derivations:: Low-level interface to package derivations.
2187 * The Store Monad:: Purely functional interface to the store.
2188 * G-Expressions:: Manipulating build expressions.
2191 @node Defining Packages
2192 @section Defining Packages
2194 The high-level interface to package definitions is implemented in the
2195 @code{(guix packages)} and @code{(guix build-system)} modules. As an
2196 example, the package definition, or @dfn{recipe}, for the GNU Hello
2197 package looks like this:
2200 (define-module (gnu packages hello)
2201 #:use-module (guix packages)
2202 #:use-module (guix download)
2203 #:use-module (guix build-system gnu)
2204 #:use-module (guix licenses)
2205 #:use-module (gnu packages gawk))
2207 (define-public hello
2213 (uri (string-append "mirror://gnu/hello/hello-" version
2217 "0ssi1wpaf7plaswqqjwigppsg5fyh99vdlb9kzl7c9lng89ndq1i"))))
2218 (build-system gnu-build-system)
2219 (arguments `(#:configure-flags '("--enable-silent-rules")))
2220 (inputs `(("gawk" ,gawk)))
2221 (synopsis "Hello, GNU world: An example GNU package")
2222 (description "Guess what GNU Hello prints!")
2223 (home-page "http://www.gnu.org/software/hello/")
2228 Without being a Scheme expert, the reader may have guessed the meaning
2229 of the various fields here. This expression binds variable @code{hello}
2230 to a @code{<package>} object, which is essentially a record
2231 (@pxref{SRFI-9, Scheme records,, guile, GNU Guile Reference Manual}).
2232 This package object can be inspected using procedures found in the
2233 @code{(guix packages)} module; for instance, @code{(package-name hello)}
2234 returns---surprise!---@code{"hello"}.
2236 With luck, you may be able to import part or all of the definition of
2237 the package you are interested in from another repository, using the
2238 @code{guix import} command (@pxref{Invoking guix import}).
2240 In the example above, @var{hello} is defined into a module of its own,
2241 @code{(gnu packages hello)}. Technically, this is not strictly
2242 necessary, but it is convenient to do so: all the packages defined in
2243 modules under @code{(gnu packages @dots{})} are automatically known to
2244 the command-line tools (@pxref{Package Modules}).
2246 There are a few points worth noting in the above package definition:
2250 The @code{source} field of the package is an @code{<origin>} object
2251 (@pxref{origin Reference}, for the complete reference).
2252 Here, the @code{url-fetch} method from @code{(guix download)} is used,
2253 meaning that the source is a file to be downloaded over FTP or HTTP.
2255 The @code{mirror://gnu} prefix instructs @code{url-fetch} to use one of
2256 the GNU mirrors defined in @code{(guix download)}.
2258 The @code{sha256} field specifies the expected SHA256 hash of the file
2259 being downloaded. It is mandatory, and allows Guix to check the
2260 integrity of the file. The @code{(base32 @dots{})} form introduces the
2261 base32 representation of the hash. You can obtain this information with
2262 @code{guix download} (@pxref{Invoking guix download}) and @code{guix
2263 hash} (@pxref{Invoking guix hash}).
2266 When needed, the @code{origin} form can also have a @code{patches} field
2267 listing patches to be applied, and a @code{snippet} field giving a
2268 Scheme expression to modify the source code.
2271 @cindex GNU Build System
2272 The @code{build-system} field specifies the procedure to build the
2273 package (@pxref{Build Systems}). Here, @var{gnu-build-system}
2274 represents the familiar GNU Build System, where packages may be
2275 configured, built, and installed with the usual @code{./configure &&
2276 make && make check && make install} command sequence.
2279 The @code{arguments} field specifies options for the build system
2280 (@pxref{Build Systems}). Here it is interpreted by
2281 @var{gnu-build-system} as a request run @file{configure} with the
2282 @code{--enable-silent-rules} flag.
2285 The @code{inputs} field specifies inputs to the build process---i.e.,
2286 build-time or run-time dependencies of the package. Here, we define an
2287 input called @code{"gawk"} whose value is that of the @var{gawk}
2288 variable; @var{gawk} is itself bound to a @code{<package>} object.
2290 Note that GCC, Coreutils, Bash, and other essential tools do not need to
2291 be specified as inputs here. Instead, @var{gnu-build-system} takes care
2292 of ensuring that they are present (@pxref{Build Systems}).
2294 However, any other dependencies need to be specified in the
2295 @code{inputs} field. Any dependency not specified here will simply be
2296 unavailable to the build process, possibly leading to a build failure.
2299 @xref{package Reference}, for a full description of possible fields.
2301 Once a package definition is in place, the
2302 package may actually be built using the @code{guix build} command-line
2303 tool (@pxref{Invoking guix build}). You can easily jump back to the
2304 package definition using the @command{guix edit} command
2305 (@pxref{Invoking guix edit}).
2306 @xref{Packaging Guidelines}, for
2307 more information on how to test package definitions, and
2308 @ref{Invoking guix lint}, for information on how to check a definition
2309 for style conformance.
2311 Eventually, updating the package definition to a new upstream version
2312 can be partly automated by the @command{guix refresh} command
2313 (@pxref{Invoking guix refresh}).
2315 Behind the scenes, a derivation corresponding to the @code{<package>}
2316 object is first computed by the @code{package-derivation} procedure.
2317 That derivation is stored in a @code{.drv} file under @file{/gnu/store}.
2318 The build actions it prescribes may then be realized by using the
2319 @code{build-derivations} procedure (@pxref{The Store}).
2321 @deffn {Scheme Procedure} package-derivation @var{store} @var{package} [@var{system}]
2322 Return the @code{<derivation>} object of @var{package} for @var{system}
2323 (@pxref{Derivations}).
2325 @var{package} must be a valid @code{<package>} object, and @var{system}
2326 must be a string denoting the target system type---e.g.,
2327 @code{"x86_64-linux"} for an x86_64 Linux-based GNU system. @var{store}
2328 must be a connection to the daemon, which operates on the store
2329 (@pxref{The Store}).
2333 @cindex cross-compilation
2334 Similarly, it is possible to compute a derivation that cross-builds a
2335 package for some other system:
2337 @deffn {Scheme Procedure} package-cross-derivation @var{store} @
2338 @var{package} @var{target} [@var{system}]
2339 Return the @code{<derivation>} object of @var{package} cross-built from
2340 @var{system} to @var{target}.
2342 @var{target} must be a valid GNU triplet denoting the target hardware
2343 and operating system, such as @code{"mips64el-linux-gnu"}
2344 (@pxref{Configuration Names, GNU configuration triplets,, configure, GNU
2345 Configure and Build System}).
2349 * package Reference :: The package data type.
2350 * origin Reference:: The origin data type.
2354 @node package Reference
2355 @subsection @code{package} Reference
2357 This section summarizes all the options available in @code{package}
2358 declarations (@pxref{Defining Packages}).
2360 @deftp {Data Type} package
2361 This is the data type representing a package recipe.
2365 The name of the package, as a string.
2367 @item @code{version}
2368 The version of the package, as a string.
2371 An origin object telling how the source code for the package should be
2372 acquired (@pxref{origin Reference}).
2374 @item @code{build-system}
2375 The build system that should be used to build the package (@pxref{Build
2378 @item @code{arguments} (default: @code{'()})
2379 The arguments that should be passed to the build system. This is a
2380 list, typically containing sequential keyword-value pairs.
2382 @item @code{inputs} (default: @code{'()})
2383 @itemx @code{native-inputs} (default: @code{'()})
2384 @itemx @code{propagated-inputs} (default: @code{'()})
2385 @cindex inputs, of packages
2386 These fields list dependencies of the package. Each one is a list of
2387 tuples, where each tuple has a label for the input (a string) as its
2388 first element, a package, origin, or derivation as its second element,
2389 and optionally the name of the output thereof that should be used, which
2390 defaults to @code{"out"} (@pxref{Packages with Multiple Outputs}, for
2391 more on package outputs). For example, the list below specifies 3
2395 `(("libffi" ,libffi)
2396 ("libunistring" ,libunistring)
2397 ("glib:bin" ,glib "bin")) ;the "bin" output of Glib
2400 @cindex cross compilation, package dependencies
2401 The distinction between @code{native-inputs} and @code{inputs} is
2402 necessary when considering cross-compilation. When cross-compiling,
2403 dependencies listed in @code{inputs} are built for the @emph{target}
2404 architecture; conversely, dependencies listed in @code{native-inputs}
2405 are built for the architecture of the @emph{build} machine.
2407 @code{native-inputs} is typically where you would list tools needed at
2408 build time but not at run time, such as Autoconf, Automake, pkg-config,
2409 Gettext, or Bison. @command{guix lint} can report likely mistakes in
2410 this area (@pxref{Invoking guix lint}).
2412 @anchor{package-propagated-inputs}
2413 Lastly, @code{propagated-inputs} is similar to @code{inputs}, but the
2414 specified packages will be force-installed alongside the package they
2415 belong to (@pxref{package-cmd-propagated-inputs, @command{guix
2416 package}}, for information on how @command{guix package} deals with
2419 For example this is necessary when a C/C++ library needs headers of
2420 another library to compile, or when a pkg-config file refers to another
2421 one @i{via} its @code{Requires} field.
2423 Another example where @code{propagated-inputs} is useful is for
2424 languages that lack a facility to record the run-time search path akin
2425 to ELF's @code{RUNPATH}; this includes Guile, Python, Perl, GHC, and
2426 more. To ensure that libraries written in those languages can find
2427 library code they depend on at run time, run-time dependencies must be
2428 listed in @code{propagated-inputs} rather than @code{inputs}.
2430 @item @code{self-native-input?} (default: @code{#f})
2431 This is a Boolean field telling whether the package should use itself as
2432 a native input when cross-compiling.
2434 @item @code{outputs} (default: @code{'("out")})
2435 The list of output names of the package. @xref{Packages with Multiple
2436 Outputs}, for typical uses of additional outputs.
2438 @item @code{native-search-paths} (default: @code{'()})
2439 @itemx @code{search-paths} (default: @code{'()})
2440 A list of @code{search-path-specification} objects describing
2441 search-path environment variables honored by the package.
2443 @item @code{replacement} (default: @code{#f})
2444 This must either @code{#f} or a package object that will be used as a
2445 @dfn{replacement} for this package. @xref{Security Updates, grafts},
2448 @item @code{synopsis}
2449 A one-line description of the package.
2451 @item @code{description}
2452 A more elaborate description of the package.
2454 @item @code{license}
2455 The license of the package; a value from @code{(guix licenses)}.
2457 @item @code{home-page}
2458 The URL to the home-page of the package, as a string.
2460 @item @code{supported-systems} (default: @var{%supported-systems})
2461 The list of systems supported by the package, as strings of the form
2462 @code{architecture-kernel}, for example @code{"x86_64-linux"}.
2464 @item @code{maintainers} (default: @code{'()})
2465 The list of maintainers of the package, as @code{maintainer} objects.
2467 @item @code{location} (default: source location of the @code{package} form)
2468 The source location of the package. It's useful to override this when
2469 inheriting from another package, in which case this field is not
2470 automatically corrected.
2475 @node origin Reference
2476 @subsection @code{origin} Reference
2478 This section summarizes all the options available in @code{origin}
2479 declarations (@pxref{Defining Packages}).
2481 @deftp {Data Type} origin
2482 This is the data type representing a source code origin.
2486 An object containing the URI of the source. The object type depends on
2487 the @code{method} (see below). For example, when using the
2488 @var{url-fetch} method of @code{(guix download)}, the valid @code{uri}
2489 values are: a URL represented as a string, or a list thereof.
2492 A procedure that will handle the URI.
2497 @item @var{url-fetch} from @code{(guix download)}
2498 download a file the HTTP, HTTPS, or FTP URL specified in the
2501 @item @var{git-fetch} from @code{(guix git-download)}
2502 clone the Git version control repository, and check out the revision
2503 specified in the @code{uri} field as a @code{git-reference} object; a
2504 @code{git-reference} looks like this:
2508 (url "git://git.debian.org/git/pkg-shadow/shadow")
2509 (commit "v4.1.5.1"))
2514 A bytevector containing the SHA-256 hash of the source. Typically the
2515 @code{base32} form is used here to generate the bytevector from a
2518 @item @code{file-name} (default: @code{#f})
2519 The file name under which the source code should be saved. When this is
2520 @code{#f}, a sensible default value will be used in most cases. In case
2521 the source is fetched from a URL, the file name from the URL will be
2522 used. For version control checkouts, it's recommended to provide the
2523 file name explicitly because the default is not very descriptive.
2525 @item @code{patches} (default: @code{'()})
2526 A list of file names containing patches to be applied to the source.
2528 @item @code{snippet} (default: @code{#f})
2529 A quoted piece of code that will be run in the source directory to make
2530 any modifications, which is sometimes more convenient than a patch.
2532 @item @code{patch-flags} (default: @code{'("-p1")})
2533 A list of command-line flags that should be passed to the @code{patch}
2536 @item @code{patch-inputs} (default: @code{#f})
2537 Input packages or derivations to the patching process. When this is
2538 @code{#f}, the usual set of inputs necessary for patching are provided,
2539 such as GNU@tie{}Patch.
2541 @item @code{modules} (default: @code{'()})
2542 A list of Guile modules that should be loaded during the patching
2543 process and while running the code in the @code{snippet} field.
2545 @item @code{imported-modules} (default: @code{'()})
2546 The list of Guile modules to import in the patch derivation, for use by
2549 @item @code{patch-guile} (default: @code{#f})
2550 The Guile package that should be used in the patching process. When
2551 this is @code{#f}, a sensible default is used.
2557 @section Build Systems
2559 @cindex build system
2560 Each package definition specifies a @dfn{build system} and arguments for
2561 that build system (@pxref{Defining Packages}). This @code{build-system}
2562 field represents the build procedure of the package, as well implicit
2563 dependencies of that build procedure.
2565 Build systems are @code{<build-system>} objects. The interface to
2566 create and manipulate them is provided by the @code{(guix build-system)}
2567 module, and actual build systems are exported by specific modules.
2569 @cindex bag (low-level package representation)
2570 Under the hood, build systems first compile package objects to
2571 @dfn{bags}. A @dfn{bag} is like a package, but with less
2572 ornamentation---in other words, a bag is a lower-level representation of
2573 a package, which includes all the inputs of that package, including some
2574 that were implicitly added by the build system. This intermediate
2575 representation is then compiled to a derivation (@pxref{Derivations}).
2577 Build systems accept an optional list of @dfn{arguments}. In package
2578 definitions, these are passed @i{via} the @code{arguments} field
2579 (@pxref{Defining Packages}). They are typically keyword arguments
2580 (@pxref{Optional Arguments, keyword arguments in Guile,, guile, GNU
2581 Guile Reference Manual}). The value of these arguments is usually
2582 evaluated in the @dfn{build stratum}---i.e., by a Guile process launched
2583 by the daemon (@pxref{Derivations}).
2585 The main build system is @var{gnu-build-system}, which implements the
2586 standard build procedure for GNU packages and many other packages. It
2587 is provided by the @code{(guix build-system gnu)} module.
2589 @defvr {Scheme Variable} gnu-build-system
2590 @var{gnu-build-system} represents the GNU Build System, and variants
2591 thereof (@pxref{Configuration, configuration and makefile conventions,,
2592 standards, GNU Coding Standards}).
2594 @cindex build phases
2595 In a nutshell, packages using it configured, built, and installed with
2596 the usual @code{./configure && make && make check && make install}
2597 command sequence. In practice, a few additional steps are often needed.
2598 All these steps are split up in separate @dfn{phases},
2599 notably@footnote{Please see the @code{(guix build gnu-build-system)}
2600 modules for more details about the build phases.}:
2604 Unpack the source tarball, and change the current directory to the
2605 extracted source tree. If the source is actually a directory, copy it
2606 to the build tree, and enter that directory.
2608 @item patch-source-shebangs
2609 Patch shebangs encountered in source files so they refer to the right
2610 store file names. For instance, this changes @code{#!/bin/sh} to
2611 @code{#!/gnu/store/@dots{}-bash-4.3/bin/sh}.
2614 Run the @file{configure} script with a number of default options, such
2615 as @code{--prefix=/gnu/store/@dots{}}, as well as the options specified
2616 by the @code{#:configure-flags} argument.
2619 Run @code{make} with the list of flags specified with
2620 @code{#:make-flags}. If the @code{#:parallel-build?} argument is true
2621 (the default), build with @code{make -j}.
2624 Run @code{make check}, or some other target specified with
2625 @code{#:test-target}, unless @code{#:tests? #f} is passed. If the
2626 @code{#:parallel-tests?} argument is true (the default), run @code{make
2630 Run @code{make install} with the flags listed in @code{#:make-flags}.
2632 @item patch-shebangs
2633 Patch shebangs on the installed executable files.
2636 Strip debugging symbols from ELF files (unless @code{#:strip-binaries?}
2637 is false), copying them to the @code{debug} output when available
2638 (@pxref{Installing Debugging Files}).
2641 @vindex %standard-phases
2642 The build-side module @code{(guix build gnu-build-system)} defines
2643 @var{%standard-phases} as the default list of build phases.
2644 @var{%standard-phases} is a list of symbol/procedure pairs, where the
2645 procedure implements the actual phase.
2647 The list of phases used for a particular package can be changed with the
2648 @code{#:phases} parameter. For instance, passing:
2651 #:phases (alist-delete 'configure %standard-phases)
2654 means that all the phases described above will be used, except the
2655 @code{configure} phase.
2657 In addition, this build system ensures that the ``standard'' environment
2658 for GNU packages is available. This includes tools such as GCC, libc,
2659 Coreutils, Bash, Make, Diffutils, grep, and sed (see the @code{(guix
2660 build-system gnu)} module for a complete list.) We call these the
2661 @dfn{implicit inputs} of a package, because package definitions don't
2662 have to mention them.
2665 Other @code{<build-system>} objects are defined to support other
2666 conventions and tools used by free software packages. They inherit most
2667 of @var{gnu-build-system}, and differ mainly in the set of inputs
2668 implicitly added to the build process, and in the list of phases
2669 executed. Some of these build systems are listed below.
2671 @defvr {Scheme Variable} cmake-build-system
2672 This variable is exported by @code{(guix build-system cmake)}. It
2673 implements the build procedure for packages using the
2674 @url{http://www.cmake.org, CMake build tool}.
2676 It automatically adds the @code{cmake} package to the set of inputs.
2677 Which package is used can be specified with the @code{#:cmake}
2680 The @code{#:configure-flags} parameter is taken as a list of flags
2681 passed to the @command{cmake} command. The @code{#:build-type}
2682 parameter specifies in abstract terms the flags passed to the compiler;
2683 it defaults to @code{"RelWithDebInfo"} (short for ``release mode with
2684 debugging information''), which roughly means that code is compiled with
2685 @code{-O2 -g}, as is the case for Autoconf-based packages by default.
2688 @defvr {Scheme Variable} glib-or-gtk-build-system
2689 This variable is exported by @code{(guix build-system glib-or-gtk)}. It
2690 is intended for use with packages making use of GLib or GTK+.
2692 This build system adds the following two phases to the ones defined by
2693 @var{gnu-build-system}:
2696 @item glib-or-gtk-wrap
2697 The phase @code{glib-or-gtk-wrap} ensures that programs found under
2698 @file{bin/} are able to find GLib's ``schemas'' and
2699 @uref{https://developer.gnome.org/gtk3/stable/gtk-running.html, GTK+
2700 modules}. This is achieved by wrapping the programs in launch scripts
2701 that appropriately set the @code{XDG_DATA_DIRS} and @code{GTK_PATH}
2702 environment variables.
2704 It is possible to exclude specific package outputs from that wrapping
2705 process by listing their names in the
2706 @code{#:glib-or-gtk-wrap-excluded-outputs} parameter. This is useful
2707 when an output is known not to contain any GLib or GTK+ binaries, and
2708 where wrapping would gratuitously add a dependency of that output on
2711 @item glib-or-gtk-compile-schemas
2712 The phase @code{glib-or-gtk-compile-schemas} makes sure that all GLib's
2713 @uref{https://developer.gnome.org/gio/stable/glib-compile-schemas.html,
2714 GSettings schemas} are compiled. Compilation is performed by the
2715 @command{glib-compile-schemas} program. It is provided by the package
2716 @code{glib:bin} which is automatically imported by the build system.
2717 The @code{glib} package providing @command{glib-compile-schemas} can be
2718 specified with the @code{#:glib} parameter.
2721 Both phases are executed after the @code{install} phase.
2724 @defvr {Scheme Variable} python-build-system
2725 This variable is exported by @code{(guix build-system python)}. It
2726 implements the more or less standard build procedure used by Python
2727 packages, which consists in running @code{python setup.py build} and
2728 then @code{python setup.py install --prefix=/gnu/store/@dots{}}.
2730 For packages that install stand-alone Python programs under @code{bin/},
2731 it takes care of wrapping these programs so their @code{PYTHONPATH}
2732 environment variable points to all the Python libraries they depend on.
2734 Which Python package is used can be specified with the @code{#:python}
2738 @defvr {Scheme Variable} perl-build-system
2739 This variable is exported by @code{(guix build-system perl)}. It
2740 implements the standard build procedure for Perl packages, which either
2741 consists in running @code{perl Build.PL --prefix=/gnu/store/@dots{}},
2742 followed by @code{Build} and @code{Build install}; or in running
2743 @code{perl Makefile.PL PREFIX=/gnu/store/@dots{}}, followed by
2744 @code{make} and @code{make install}; depending on which of
2745 @code{Build.PL} or @code{Makefile.PL} is present in the package
2746 distribution. Preference is given to the former if both @code{Build.PL}
2747 and @code{Makefile.PL} exist in the package distribution. This
2748 preference can be reversed by specifying @code{#t} for the
2749 @code{#:make-maker?} parameter.
2751 The initial @code{perl Makefile.PL} or @code{perl Build.PL} invocation
2752 passes flags specified by the @code{#:make-maker-flags} or
2753 @code{#:module-build-flags} parameter, respectively.
2755 Which Perl package is used can be specified with @code{#:perl}.
2758 @defvr {Scheme Variable} r-build-system
2759 This variable is exported by @code{(guix build-system r)}. It
2760 implements the build procedure used by @uref{http://r-project.org, R}
2761 packages, which essentially is little more than running @code{R CMD
2762 INSTALL --library=/gnu/store/@dots{}} in an environment where
2763 @code{R_LIBS_SITE} contains the paths to all R package inputs. Tests
2764 are run after installation using the R function
2765 @code{tools::testInstalledPackage}.
2768 @defvr {Scheme Variable} ruby-build-system
2769 This variable is exported by @code{(guix build-system ruby)}. It
2770 implements the RubyGems build procedure used by Ruby packages, which
2771 involves running @code{gem build} followed by @code{gem install}.
2773 The @code{source} field of a package that uses this build system
2774 typically references a gem archive, since this is the format that Ruby
2775 developers use when releasing their software. The build system unpacks
2776 the gem archive, potentially patches the source, runs the test suite,
2777 repackages the gem, and installs it. Additionally, directories and
2778 tarballs may be referenced to allow building unreleased gems from Git or
2779 a traditional source release tarball.
2781 Which Ruby package is used can be specified with the @code{#:ruby}
2782 parameter. A list of additional flags to be passed to the @command{gem}
2783 command can be specified with the @code{#:gem-flags} parameter.
2786 @defvr {Scheme Variable} waf-build-system
2787 This variable is exported by @code{(guix build-system waf)}. It
2788 implements a build procedure around the @code{waf} script. The common
2789 phases---@code{configure}, @code{build}, and @code{install}---are
2790 implemented by passing their names as arguments to the @code{waf}
2793 The @code{waf} script is executed by the Python interpreter. Which
2794 Python package is used to run the script can be specified with the
2795 @code{#:python} parameter.
2798 @defvr {Scheme Variable} haskell-build-system
2799 This variable is exported by @code{(guix build-system haskell)}. It
2800 implements the Cabal build procedure used by Haskell packages, which
2801 involves running @code{runhaskell Setup.hs configure
2802 --prefix=/gnu/store/@dots{}} and @code{runhaskell Setup.hs build}.
2803 Instead of installing the package by running @code{runhaskell Setup.hs
2804 install}, to avoid trying to register libraries in the read-only
2805 compiler store directory, the build system uses @code{runhaskell
2806 Setup.hs copy}, followed by @code{runhaskell Setup.hs register}. In
2807 addition, the build system generates the package documentation by
2808 running @code{runhaskell Setup.hs haddock}, unless @code{#:haddock? #f}
2809 is passed. Optional Haddock parameters can be passed with the help of
2810 the @code{#:haddock-flags} parameter. If the file @code{Setup.hs} is
2811 not found, the build system looks for @code{Setup.lhs} instead.
2813 Which Haskell compiler is used can be specified with the @code{#:haskell}
2814 parameter which defaults to @code{ghc}.
2817 @defvr {Scheme Variable} emacs-build-system
2818 This variable is exported by @code{(guix build-system emacs)}. It
2819 implements an installation procedure similar to the one of Emacs' own
2820 packaging system (@pxref{Packages,,, emacs, The GNU Emacs Manual}).
2822 It first creates the @code{@var{package}-autoloads.el} file, then it
2823 byte compiles all Emacs Lisp files. Differently from the Emacs
2824 packaging system, the Info documentation files are moved to the standard
2825 documentation directory and the @file{dir} file is deleted. Each
2826 package is installed in its own directory under
2827 @file{share/emacs/site-lisp/guix.d}.
2830 Lastly, for packages that do not need anything as sophisticated, a
2831 ``trivial'' build system is provided. It is trivial in the sense that
2832 it provides basically no support: it does not pull any implicit inputs,
2833 and does not have a notion of build phases.
2835 @defvr {Scheme Variable} trivial-build-system
2836 This variable is exported by @code{(guix build-system trivial)}.
2838 This build system requires a @code{#:builder} argument. This argument
2839 must be a Scheme expression that builds the package's output(s)---as
2840 with @code{build-expression->derivation} (@pxref{Derivations,
2841 @code{build-expression->derivation}}).
2850 Conceptually, the @dfn{store} is where derivations that have been
2851 successfully built are stored---by default, under @file{/gnu/store}.
2852 Sub-directories in the store are referred to as @dfn{store paths}. The
2853 store has an associated database that contains information such as the
2854 store paths referred to by each store path, and the list of @emph{valid}
2855 store paths---paths that result from a successful build.
2857 The store is always accessed by the daemon on behalf of its clients
2858 (@pxref{Invoking guix-daemon}). To manipulate the store, clients
2859 connect to the daemon over a Unix-domain socket, send it requests, and
2860 read the result---these are remote procedure calls, or RPCs.
2862 The @code{(guix store)} module provides procedures to connect to the
2863 daemon, and to perform RPCs. These are described below.
2865 @deffn {Scheme Procedure} open-connection [@var{file}] [#:reserve-space? #t]
2866 Connect to the daemon over the Unix-domain socket at @var{file}. When
2867 @var{reserve-space?} is true, instruct it to reserve a little bit of
2868 extra space on the file system so that the garbage collector can still
2869 operate, should the disk become full. Return a server object.
2871 @var{file} defaults to @var{%default-socket-path}, which is the normal
2872 location given the options that were passed to @command{configure}.
2875 @deffn {Scheme Procedure} close-connection @var{server}
2876 Close the connection to @var{server}.
2879 @defvr {Scheme Variable} current-build-output-port
2880 This variable is bound to a SRFI-39 parameter, which refers to the port
2881 where build and error logs sent by the daemon should be written.
2884 Procedures that make RPCs all take a server object as their first
2887 @deffn {Scheme Procedure} valid-path? @var{server} @var{path}
2888 Return @code{#t} when @var{path} is a valid store path.
2891 @deffn {Scheme Procedure} add-text-to-store @var{server} @var{name} @var{text} [@var{references}]
2892 Add @var{text} under file @var{name} in the store, and return its store
2893 path. @var{references} is the list of store paths referred to by the
2894 resulting store path.
2897 @deffn {Scheme Procedure} build-derivations @var{server} @var{derivations}
2898 Build @var{derivations} (a list of @code{<derivation>} objects or
2899 derivation paths), and return when the worker is done building them.
2900 Return @code{#t} on success.
2903 Note that the @code{(guix monads)} module provides a monad as well as
2904 monadic versions of the above procedures, with the goal of making it
2905 more convenient to work with code that accesses the store (@pxref{The
2909 @i{This section is currently incomplete.}
2912 @section Derivations
2915 Low-level build actions and the environment in which they are performed
2916 are represented by @dfn{derivations}. A derivation contain the
2917 following pieces of information:
2921 The outputs of the derivation---derivations produce at least one file or
2922 directory in the store, but may produce more.
2925 The inputs of the derivations, which may be other derivations or plain
2926 files in the store (patches, build scripts, etc.)
2929 The system type targeted by the derivation---e.g., @code{x86_64-linux}.
2932 The file name of a build script in the store, along with the arguments
2936 A list of environment variables to be defined.
2940 @cindex derivation path
2941 Derivations allow clients of the daemon to communicate build actions to
2942 the store. They exist in two forms: as an in-memory representation,
2943 both on the client- and daemon-side, and as files in the store whose
2944 name end in @code{.drv}---these files are referred to as @dfn{derivation
2945 paths}. Derivations paths can be passed to the @code{build-derivations}
2946 procedure to perform the build actions they prescribe (@pxref{The
2949 The @code{(guix derivations)} module provides a representation of
2950 derivations as Scheme objects, along with procedures to create and
2951 otherwise manipulate derivations. The lowest-level primitive to create
2952 a derivation is the @code{derivation} procedure:
2954 @deffn {Scheme Procedure} derivation @var{store} @var{name} @var{builder} @
2955 @var{args} [#:outputs '("out")] [#:hash #f] [#:hash-algo #f] @
2956 [#:recursive? #f] [#:inputs '()] [#:env-vars '()] @
2957 [#:system (%current-system)] [#:references-graphs #f] @
2958 [#:allowed-references #f] [#:leaked-env-vars #f] [#:local-build? #f] @
2959 [#:substitutable? #t]
2960 Build a derivation with the given arguments, and return the resulting
2961 @code{<derivation>} object.
2963 When @var{hash} and @var{hash-algo} are given, a
2964 @dfn{fixed-output derivation} is created---i.e., one whose result is
2965 known in advance, such as a file download. If, in addition,
2966 @var{recursive?} is true, then that fixed output may be an executable
2967 file or a directory and @var{hash} must be the hash of an archive
2968 containing this output.
2970 When @var{references-graphs} is true, it must be a list of file
2971 name/store path pairs. In that case, the reference graph of each store
2972 path is exported in the build environment in the corresponding file, in
2973 a simple text format.
2975 When @var{allowed-references} is true, it must be a list of store items
2976 or outputs that the derivation's output may refer to.
2978 When @var{leaked-env-vars} is true, it must be a list of strings
2979 denoting environment variables that are allowed to ``leak'' from the
2980 daemon's environment to the build environment. This is only applicable
2981 to fixed-output derivations---i.e., when @var{hash} is true. The main
2982 use is to allow variables such as @code{http_proxy} to be passed to
2983 derivations that download files.
2985 When @var{local-build?} is true, declare that the derivation is not a
2986 good candidate for offloading and should rather be built locally
2987 (@pxref{Daemon Offload Setup}). This is the case for small derivations
2988 where the costs of data transfers would outweigh the benefits.
2990 When @var{substitutable?} is false, declare that substitutes of the
2991 derivation's output should not be used (@pxref{Substitutes}). This is
2992 useful, for instance, when building packages that capture details of the
2993 host CPU instruction set.
2997 Here's an example with a shell script as its builder, assuming
2998 @var{store} is an open connection to the daemon, and @var{bash} points
2999 to a Bash executable in the store:
3002 (use-modules (guix utils)
3006 (let ((builder ; add the Bash script to the store
3007 (add-text-to-store store "my-builder.sh"
3008 "echo hello world > $out\n" '())))
3009 (derivation store "foo"
3010 bash `("-e" ,builder)
3011 #:inputs `((,bash) (,builder))
3012 #:env-vars '(("HOME" . "/homeless"))))
3013 @result{} #<derivation /gnu/store/@dots{}-foo.drv => /gnu/store/@dots{}-foo>
3016 As can be guessed, this primitive is cumbersome to use directly. A
3017 better approach is to write build scripts in Scheme, of course! The
3018 best course of action for that is to write the build code as a
3019 ``G-expression'', and to pass it to @code{gexp->derivation}. For more
3020 information, @pxref{G-Expressions}.
3022 Once upon a time, @code{gexp->derivation} did not exist and constructing
3023 derivations with build code written in Scheme was achieved with
3024 @code{build-expression->derivation}, documented below. This procedure
3025 is now deprecated in favor of the much nicer @code{gexp->derivation}.
3027 @deffn {Scheme Procedure} build-expression->derivation @var{store} @
3028 @var{name} @var{exp} @
3029 [#:system (%current-system)] [#:inputs '()] @
3030 [#:outputs '("out")] [#:hash #f] [#:hash-algo #f] @
3031 [#:recursive? #f] [#:env-vars '()] [#:modules '()] @
3032 [#:references-graphs #f] [#:allowed-references #f] @
3033 [#:local-build? #f] [#:substitutable? #t] [#:guile-for-build #f]
3034 Return a derivation that executes Scheme expression @var{exp} as a
3035 builder for derivation @var{name}. @var{inputs} must be a list of
3036 @code{(name drv-path sub-drv)} tuples; when @var{sub-drv} is omitted,
3037 @code{"out"} is assumed. @var{modules} is a list of names of Guile
3038 modules from the current search path to be copied in the store,
3039 compiled, and made available in the load path during the execution of
3040 @var{exp}---e.g., @code{((guix build utils) (guix build
3041 gnu-build-system))}.
3043 @var{exp} is evaluated in an environment where @code{%outputs} is bound
3044 to a list of output/path pairs, and where @code{%build-inputs} is bound
3045 to a list of string/output-path pairs made from @var{inputs}.
3046 Optionally, @var{env-vars} is a list of string pairs specifying the name
3047 and value of environment variables visible to the builder. The builder
3048 terminates by passing the result of @var{exp} to @code{exit}; thus, when
3049 @var{exp} returns @code{#f}, the build is considered to have failed.
3051 @var{exp} is built using @var{guile-for-build} (a derivation). When
3052 @var{guile-for-build} is omitted or is @code{#f}, the value of the
3053 @code{%guile-for-build} fluid is used instead.
3055 See the @code{derivation} procedure for the meaning of
3056 @var{references-graphs}, @var{allowed-references}, @var{local-build?},
3057 and @var{substitutable?}.
3061 Here's an example of a single-output derivation that creates a directory
3062 containing one file:
3065 (let ((builder '(let ((out (assoc-ref %outputs "out")))
3066 (mkdir out) ; create /gnu/store/@dots{}-goo
3067 (call-with-output-file (string-append out "/test")
3069 (display '(hello guix) p))))))
3070 (build-expression->derivation store "goo" builder))
3072 @result{} #<derivation /gnu/store/@dots{}-goo.drv => @dots{}>
3076 @node The Store Monad
3077 @section The Store Monad
3081 The procedures that operate on the store described in the previous
3082 sections all take an open connection to the build daemon as their first
3083 argument. Although the underlying model is functional, they either have
3084 side effects or depend on the current state of the store.
3086 The former is inconvenient: the connection to the build daemon has to be
3087 carried around in all those functions, making it impossible to compose
3088 functions that do not take that parameter with functions that do. The
3089 latter can be problematic: since store operations have side effects
3090 and/or depend on external state, they have to be properly sequenced.
3092 @cindex monadic values
3093 @cindex monadic functions
3094 This is where the @code{(guix monads)} module comes in. This module
3095 provides a framework for working with @dfn{monads}, and a particularly
3096 useful monad for our uses, the @dfn{store monad}. Monads are a
3097 construct that allows two things: associating ``context'' with values
3098 (in our case, the context is the store), and building sequences of
3099 computations (here computations include accesses to the store.) Values
3100 in a monad---values that carry this additional context---are called
3101 @dfn{monadic values}; procedures that return such values are called
3102 @dfn{monadic procedures}.
3104 Consider this ``normal'' procedure:
3107 (define (sh-symlink store)
3108 ;; Return a derivation that symlinks the 'bash' executable.
3109 (let* ((drv (package-derivation store bash))
3110 (out (derivation->output-path drv))
3111 (sh (string-append out "/bin/bash")))
3112 (build-expression->derivation store "sh"
3113 `(symlink ,sh %output))))
3116 Using @code{(guix monads)} and @code{(guix gexp)}, it may be rewritten
3117 as a monadic function:
3120 (define (sh-symlink)
3121 ;; Same, but return a monadic value.
3122 (mlet %store-monad ((drv (package->derivation bash)))
3123 (gexp->derivation "sh"
3124 #~(symlink (string-append #$drv "/bin/bash")
3128 There several things to note in the second version: the @code{store}
3129 parameter is now implicit and is ``threaded'' in the calls to the
3130 @code{package->derivation} and @code{gexp->derivation} monadic
3131 procedures, and the monadic value returned by @code{package->derivation}
3132 is @dfn{bound} using @code{mlet} instead of plain @code{let}.
3134 As it turns out, the call to @code{package->derivation} can even be
3135 omitted since it will take place implicitly, as we will see later
3136 (@pxref{G-Expressions}):
3139 (define (sh-symlink)
3140 (gexp->derivation "sh"
3141 #~(symlink (string-append #$bash "/bin/bash")
3146 @c <https://syntaxexclamation.wordpress.com/2014/06/26/escaping-continuations/>
3147 @c for the funny quote.
3148 Calling the monadic @code{sh-symlink} has no effect. As someone once
3149 said, ``you exit a monad like you exit a building on fire: by running''.
3150 So, to exit the monad and get the desired effect, one must use
3151 @code{run-with-store}:
3154 (run-with-store (open-connection) (sh-symlink))
3155 @result{} /gnu/store/...-sh-symlink
3158 Note that the @code{(guix monad-repl)} module extends Guile's REPL with
3159 new ``meta-commands'' to make it easier to deal with monadic procedures:
3160 @code{run-in-store}, and @code{enter-store-monad}. The former, is used
3161 to ``run'' a single monadic value through the store:
3164 scheme@@(guile-user)> ,run-in-store (package->derivation hello)
3165 $1 = #<derivation /gnu/store/@dots{}-hello-2.9.drv => @dots{}>
3168 The latter enters a recursive REPL, where all the return values are
3169 automatically run through the store:
3172 scheme@@(guile-user)> ,enter-store-monad
3173 store-monad@@(guile-user) [1]> (package->derivation hello)
3174 $2 = #<derivation /gnu/store/@dots{}-hello-2.9.drv => @dots{}>
3175 store-monad@@(guile-user) [1]> (text-file "foo" "Hello!")
3176 $3 = "/gnu/store/@dots{}-foo"
3177 store-monad@@(guile-user) [1]> ,q
3178 scheme@@(guile-user)>
3182 Note that non-monadic values cannot be returned in the
3183 @code{store-monad} REPL.
3185 The main syntactic forms to deal with monads in general are provided by
3186 the @code{(guix monads)} module and are described below.
3188 @deffn {Scheme Syntax} with-monad @var{monad} @var{body} ...
3189 Evaluate any @code{>>=} or @code{return} forms in @var{body} as being
3193 @deffn {Scheme Syntax} return @var{val}
3194 Return a monadic value that encapsulates @var{val}.
3197 @deffn {Scheme Syntax} >>= @var{mval} @var{mproc} ...
3198 @dfn{Bind} monadic value @var{mval}, passing its ``contents'' to monadic
3199 procedures @var{mproc}@dots{}@footnote{This operation is commonly
3200 referred to as ``bind'', but that name denotes an unrelated procedure in
3201 Guile. Thus we use this somewhat cryptic symbol inherited from the
3202 Haskell language.}. There can be one @var{mproc} or several of them, as
3207 (with-monad %state-monad
3209 (lambda (x) (return (+ 1 x)))
3210 (lambda (x) (return (* 2 x)))))
3214 @result{} some-state
3218 @deffn {Scheme Syntax} mlet @var{monad} ((@var{var} @var{mval}) ...) @
3220 @deffnx {Scheme Syntax} mlet* @var{monad} ((@var{var} @var{mval}) ...) @
3222 Bind the variables @var{var} to the monadic values @var{mval} in
3223 @var{body}. The form (@var{var} -> @var{val}) binds @var{var} to the
3224 ``normal'' value @var{val}, as per @code{let}.
3226 @code{mlet*} is to @code{mlet} what @code{let*} is to @code{let}
3227 (@pxref{Local Bindings,,, guile, GNU Guile Reference Manual}).
3230 @deffn {Scheme System} mbegin @var{monad} @var{mexp} ...
3231 Bind @var{mexp} and the following monadic expressions in sequence,
3232 returning the result of the last expression.
3234 This is akin to @code{mlet}, except that the return values of the
3235 monadic expressions are ignored. In that sense, it is analogous to
3236 @code{begin}, but applied to monadic expressions.
3240 The @code{(guix monads)} module provides the @dfn{state monad}, which
3241 allows an additional value---the state---to be @emph{threaded} through
3242 monadic procedure calls.
3244 @defvr {Scheme Variable} %state-monad
3245 The state monad. Procedures in the state monad can access and change
3246 the state that is threaded.
3248 Consider the example below. The @code{square} procedure returns a value
3249 in the state monad. It returns the square of its argument, but also
3250 increments the current state value:
3254 (mlet %state-monad ((count (current-state)))
3255 (mbegin %state-monad
3256 (set-current-state (+ 1 count))
3259 (run-with-state (sequence %state-monad (map square (iota 3))) 0)
3264 When ``run'' through @var{%state-monad}, we obtain that additional state
3265 value, which is the number of @code{square} calls.
3268 @deffn {Monadic Procedure} current-state
3269 Return the current state as a monadic value.
3272 @deffn {Monadic Procedure} set-current-state @var{value}
3273 Set the current state to @var{value} and return the previous state as a
3277 @deffn {Monadic Procedure} state-push @var{value}
3278 Push @var{value} to the current state, which is assumed to be a list,
3279 and return the previous state as a monadic value.
3282 @deffn {Monadic Procedure} state-pop
3283 Pop a value from the current state and return it as a monadic value.
3284 The state is assumed to be a list.
3287 @deffn {Scheme Procedure} run-with-state @var{mval} [@var{state}]
3288 Run monadic value @var{mval} starting with @var{state} as the initial
3289 state. Return two values: the resulting value, and the resulting state.
3292 The main interface to the store monad, provided by the @code{(guix
3293 store)} module, is as follows.
3295 @defvr {Scheme Variable} %store-monad
3296 The store monad---an alias for @var{%state-monad}.
3298 Values in the store monad encapsulate accesses to the store. When its
3299 effect is needed, a value of the store monad must be ``evaluated'' by
3300 passing it to the @code{run-with-store} procedure (see below.)
3303 @deffn {Scheme Procedure} run-with-store @var{store} @var{mval} [#:guile-for-build] [#:system (%current-system)]
3304 Run @var{mval}, a monadic value in the store monad, in @var{store}, an
3305 open store connection.
3308 @deffn {Monadic Procedure} text-file @var{name} @var{text} [@var{references}]
3309 Return as a monadic value the absolute file name in the store of the file
3310 containing @var{text}, a string. @var{references} is a list of store items that the
3311 resulting text file refers to; it defaults to the empty list.
3314 @deffn {Monadic Procedure} interned-file @var{file} [@var{name}] @
3316 Return the name of @var{file} once interned in the store. Use
3317 @var{name} as its store name, or the basename of @var{file} if
3318 @var{name} is omitted.
3320 When @var{recursive?} is true, the contents of @var{file} are added
3321 recursively; if @var{file} designates a flat file and @var{recursive?}
3322 is true, its contents are added, and its permission bits are kept.
3324 The example below adds a file to the store, under two different names:
3327 (run-with-store (open-connection)
3328 (mlet %store-monad ((a (interned-file "README"))
3329 (b (interned-file "README" "LEGU-MIN")))
3330 (return (list a b))))
3332 @result{} ("/gnu/store/rwm@dots{}-README" "/gnu/store/44i@dots{}-LEGU-MIN")
3337 The @code{(guix packages)} module exports the following package-related
3340 @deffn {Monadic Procedure} package-file @var{package} [@var{file}] @
3341 [#:system (%current-system)] [#:target #f] @
3342 [#:output "out"] Return as a monadic
3343 value in the absolute file name of @var{file} within the @var{output}
3344 directory of @var{package}. When @var{file} is omitted, return the name
3345 of the @var{output} directory of @var{package}. When @var{target} is
3346 true, use it as a cross-compilation target triplet.
3349 @deffn {Monadic Procedure} package->derivation @var{package} [@var{system}]
3350 @deffnx {Monadic Procedure} package->cross-derivation @var{package} @
3351 @var{target} [@var{system}]
3352 Monadic version of @code{package-derivation} and
3353 @code{package-cross-derivation} (@pxref{Defining Packages}).
3358 @section G-Expressions
3360 @cindex G-expression
3361 @cindex build code quoting
3362 So we have ``derivations'', which represent a sequence of build actions
3363 to be performed to produce an item in the store (@pxref{Derivations}).
3364 Those build actions are performed when asking the daemon to actually
3365 build the derivations; they are run by the daemon in a container
3366 (@pxref{Invoking guix-daemon}).
3368 @cindex strata of code
3369 It should come as no surprise that we like to write those build actions
3370 in Scheme. When we do that, we end up with two @dfn{strata} of Scheme
3371 code@footnote{The term @dfn{stratum} in this context was coined by
3372 Manuel Serrano et al.@: in the context of their work on Hop. Oleg
3373 Kiselyov, who has written insightful
3374 @url{http://okmij.org/ftp/meta-programming/#meta-scheme, essays and code
3375 on this topic}, refers to this kind of code generation as
3376 @dfn{staging}.}: the ``host code''---code that defines packages, talks
3377 to the daemon, etc.---and the ``build code''---code that actually
3378 performs build actions, such as making directories, invoking
3379 @command{make}, etc.
3381 To describe a derivation and its build actions, one typically needs to
3382 embed build code inside host code. It boils down to manipulating build
3383 code as data, and Scheme's homoiconicity---code has a direct
3384 representation as data---comes in handy for that. But we need more than
3385 Scheme's normal @code{quasiquote} mechanism to construct build
3388 The @code{(guix gexp)} module implements @dfn{G-expressions}, a form of
3389 S-expressions adapted to build expressions. G-expressions, or
3390 @dfn{gexps}, consist essentially in three syntactic forms: @code{gexp},
3391 @code{ungexp}, and @code{ungexp-splicing} (or simply: @code{#~},
3392 @code{#$}, and @code{#$@@}), which are comparable respectively to
3393 @code{quasiquote}, @code{unquote}, and @code{unquote-splicing}
3394 (@pxref{Expression Syntax, @code{quasiquote},, guile, GNU Guile
3395 Reference Manual}). However, there are major differences:
3399 Gexps are meant to be written to a file and run or manipulated by other
3403 When a high-level object such as a package or derivation is unquoted
3404 inside a gexp, the result is as if its output file name had been
3408 Gexps carry information about the packages or derivations they refer to,
3409 and these dependencies are automatically added as inputs to the build
3410 processes that use them.
3413 @cindex lowering, of high-level objects in gexps
3414 This mechanism is not limited to package and derivation
3415 objects: @dfn{compilers} able to ``lower'' other high-level objects to
3416 derivations or files in the store can be defined,
3417 such that these objects can also be inserted
3418 into gexps. For example, a useful type of high-level object that can be
3419 inserted in a gexp is ``file-like objects'', which make it easy to
3420 add files to the store and refer to them in
3421 derivations and such (see @code{local-file} and @code{plain-file}
3424 To illustrate the idea, here is an example of a gexp:
3431 (symlink (string-append #$coreutils "/bin/ls")
3435 This gexp can be passed to @code{gexp->derivation}; we obtain a
3436 derivation that builds a directory containing exactly one symlink to
3437 @file{/gnu/store/@dots{}-coreutils-8.22/bin/ls}:
3440 (gexp->derivation "the-thing" build-exp)
3443 As one would expect, the @code{"/gnu/store/@dots{}-coreutils-8.22"} string is
3444 substituted to the reference to the @var{coreutils} package in the
3445 actual build code, and @var{coreutils} is automatically made an input to
3446 the derivation. Likewise, @code{#$output} (equivalent to @code{(ungexp
3447 output)}) is replaced by a string containing the derivation's output
3450 @cindex cross compilation
3451 In a cross-compilation context, it is useful to distinguish between
3452 references to the @emph{native} build of a package---that can run on the
3453 host---versus references to cross builds of a package. To that end, the
3454 @code{#+} plays the same role as @code{#$}, but is a reference to a
3455 native package build:
3458 (gexp->derivation "vi"
3461 (system* (string-append #+coreutils "/bin/ln")
3463 (string-append #$emacs "/bin/emacs")
3464 (string-append #$output "/bin/vi")))
3465 #:target "mips64el-linux")
3469 In the example above, the native build of @var{coreutils} is used, so
3470 that @command{ln} can actually run on the host; but then the
3471 cross-compiled build of @var{emacs} is referenced.
3473 The syntactic form to construct gexps is summarized below.
3475 @deffn {Scheme Syntax} #~@var{exp}
3476 @deffnx {Scheme Syntax} (gexp @var{exp})
3477 Return a G-expression containing @var{exp}. @var{exp} may contain one
3478 or more of the following forms:
3482 @itemx (ungexp @var{obj})
3483 Introduce a reference to @var{obj}. @var{obj} may have one of the
3484 supported types, for example a package or a
3485 derivation, in which case the @code{ungexp} form is replaced by its
3486 output file name---e.g., @code{"/gnu/store/@dots{}-coreutils-8.22}.
3488 If @var{obj} is a list, it is traversed and references to supported
3489 objects are substituted similarly.
3491 If @var{obj} is another gexp, its contents are inserted and its
3492 dependencies are added to those of the containing gexp.
3494 If @var{obj} is another kind of object, it is inserted as is.
3496 @item #$@var{obj}:@var{output}
3497 @itemx (ungexp @var{obj} @var{output})
3498 This is like the form above, but referring explicitly to the
3499 @var{output} of @var{obj}---this is useful when @var{obj} produces
3500 multiple outputs (@pxref{Packages with Multiple Outputs}).
3503 @itemx #+@var{obj}:output
3504 @itemx (ungexp-native @var{obj})
3505 @itemx (ungexp-native @var{obj} @var{output})
3506 Same as @code{ungexp}, but produces a reference to the @emph{native}
3507 build of @var{obj} when used in a cross compilation context.
3509 @item #$output[:@var{output}]
3510 @itemx (ungexp output [@var{output}])
3511 Insert a reference to derivation output @var{output}, or to the main
3512 output when @var{output} is omitted.
3514 This only makes sense for gexps passed to @code{gexp->derivation}.
3517 @itemx (ungexp-splicing @var{lst})
3518 Like the above, but splices the contents of @var{lst} inside the
3522 @itemx (ungexp-native-splicing @var{lst})
3523 Like the above, but refers to native builds of the objects listed in
3528 G-expressions created by @code{gexp} or @code{#~} are run-time objects
3529 of the @code{gexp?} type (see below.)
3532 @deffn {Scheme Procedure} gexp? @var{obj}
3533 Return @code{#t} if @var{obj} is a G-expression.
3536 G-expressions are meant to be written to disk, either as code building
3537 some derivation, or as plain files in the store. The monadic procedures
3538 below allow you to do that (@pxref{The Store Monad}, for more
3539 information about monads.)
3541 @deffn {Monadic Procedure} gexp->derivation @var{name} @var{exp} @
3542 [#:system (%current-system)] [#:target #f] [#:graft? #t] @
3543 [#:hash #f] [#:hash-algo #f] @
3544 [#:recursive? #f] [#:env-vars '()] [#:modules '()] @
3545 [#:module-path @var{%load-path}] @
3546 [#:references-graphs #f] [#:allowed-references #f] @
3547 [#:leaked-env-vars #f] @
3548 [#:script-name (string-append @var{name} "-builder")] @
3549 [#:local-build? #f] [#:substitutable? #t] [#:guile-for-build #f]
3550 Return a derivation @var{name} that runs @var{exp} (a gexp) with
3551 @var{guile-for-build} (a derivation) on @var{system}; @var{exp} is
3552 stored in a file called @var{script-name}. When @var{target} is true,
3553 it is used as the cross-compilation target triplet for packages referred
3556 Make @var{modules} available in the evaluation context of @var{exp};
3557 @var{modules} is a list of names of Guile modules searched in
3558 @var{module-path} to be copied in the store, compiled, and made available in
3559 the load path during the execution of @var{exp}---e.g., @code{((guix
3560 build utils) (guix build gnu-build-system))}.
3562 @var{graft?} determines whether packages referred to by @var{exp} should be grafted when
3565 When @var{references-graphs} is true, it must be a list of tuples of one of the
3569 (@var{file-name} @var{package})
3570 (@var{file-name} @var{package} @var{output})
3571 (@var{file-name} @var{derivation})
3572 (@var{file-name} @var{derivation} @var{output})
3573 (@var{file-name} @var{store-item})
3576 The right-hand-side of each element of @var{references-graphs} is automatically made
3577 an input of the build process of @var{exp}. In the build environment, each
3578 @var{file-name} contains the reference graph of the corresponding item, in a simple
3581 @var{allowed-references} must be either @code{#f} or a list of output names and packages.
3582 In the latter case, the list denotes store items that the result is allowed to
3583 refer to. Any reference to another store item will lead to a build error.
3585 The other arguments are as for @code{derivation} (@pxref{Derivations}).
3588 @cindex file-like objects
3589 The @code{local-file}, @code{plain-file}, @code{computed-file},
3590 @code{program-file}, and @code{scheme-file} procedures below return
3591 @dfn{file-like objects}. That is, when unquoted in a G-expression,
3592 these objects lead to a file in the store. Consider this G-expression:
3595 #~(system* (string-append #$glibc "/sbin/nscd") "-f"
3596 #$(local-file "/tmp/my-nscd.conf"))
3599 The effect here is to ``intern'' @file{/tmp/my-nscd.conf} by copying it
3600 to the store. Once expanded, for instance @i{via}
3601 @code{gexp->derivation}, the G-expression refers to that copy under
3602 @file{/gnu/store}; thus, modifying or removing the file in @file{/tmp}
3603 does not have any effect on what the G-expression does.
3604 @code{plain-file} can be used similarly; it differs in that the file
3605 content is directly passed as a string.
3607 @deffn {Scheme Procedure} local-file @var{file} [@var{name}] @
3609 Return an object representing local file @var{file} to add to the store; this
3610 object can be used in a gexp. If @var{file} is a relative file name, it is looked
3611 up relative to the source file where this form appears. @var{file} will be added to
3612 the store under @var{name}--by default the base name of @var{file}.
3614 When @var{recursive?} is true, the contents of @var{file} are added recursively; if @var{file}
3615 designates a flat file and @var{recursive?} is true, its contents are added, and its
3616 permission bits are kept.
3618 This is the declarative counterpart of the @code{interned-file} monadic
3619 procedure (@pxref{The Store Monad, @code{interned-file}}).
3622 @deffn {Scheme Procedure} plain-file @var{name} @var{content}
3623 Return an object representing a text file called @var{name} with the given
3624 @var{content} (a string) to be added to the store.
3626 This is the declarative counterpart of @code{text-file}.
3629 @deffn {Scheme Procedure} computed-file @var{name} @var{gexp} @
3630 [#:modules '()] [#:options '(#:local-build? #t)]
3631 Return an object representing the store item @var{name}, a file or
3632 directory computed by @var{gexp}. @var{modules} specifies the set of
3633 modules visible in the execution context of @var{gexp}. @var{options}
3634 is a list of additional arguments to pass to @code{gexp->derivation}.
3636 This is the declarative counterpart of @code{gexp->derivation}.
3639 @deffn {Monadic Procedure} gexp->script @var{name} @var{exp}
3640 Return an executable script @var{name} that runs @var{exp} using
3641 @var{guile} with @var{modules} in its search path.
3643 The example below builds a script that simply invokes the @command{ls}
3647 (use-modules (guix gexp) (gnu packages base))
3649 (gexp->script "list-files"
3650 #~(execl (string-append #$coreutils "/bin/ls")
3654 When ``running'' it through the store (@pxref{The Store Monad,
3655 @code{run-with-store}}), we obtain a derivation that produces an
3656 executable file @file{/gnu/store/@dots{}-list-files} along these lines:
3659 #!/gnu/store/@dots{}-guile-2.0.11/bin/guile -ds
3661 (execl (string-append "/gnu/store/@dots{}-coreutils-8.22"/bin/ls")
3666 @deffn {Scheme Procedure} program-file @var{name} @var{exp} @
3667 [#:modules '()] [#:guile #f]
3668 Return an object representing the executable store item @var{name} that
3669 runs @var{gexp}. @var{guile} is the Guile package used to execute that
3670 script, and @var{modules} is the list of modules visible to that script.
3672 This is the declarative counterpart of @code{gexp->script}.
3675 @deffn {Monadic Procedure} gexp->file @var{name} @var{exp}
3676 Return a derivation that builds a file @var{name} containing @var{exp}.
3678 The resulting file holds references to all the dependencies of @var{exp}
3679 or a subset thereof.
3682 @deffn {Scheme Procedure} scheme-file @var{name} @var{exp}
3683 Return an object representing the Scheme file @var{name} that contains
3686 This is the declarative counterpart of @code{gexp->file}.
3689 @deffn {Monadic Procedure} text-file* @var{name} @var{text} @dots{}
3690 Return as a monadic value a derivation that builds a text file
3691 containing all of @var{text}. @var{text} may list, in addition to
3692 strings, objects of any type that can be used in a gexp: packages,
3693 derivations, local file objects, etc. The resulting store file holds
3694 references to all these.
3696 This variant should be preferred over @code{text-file} anytime the file
3697 to create will reference items from the store. This is typically the
3698 case when building a configuration file that embeds store file names,
3702 (define (profile.sh)
3703 ;; Return the name of a shell script in the store that
3704 ;; initializes the 'PATH' environment variable.
3705 (text-file* "profile.sh"
3706 "export PATH=" coreutils "/bin:"
3707 grep "/bin:" sed "/bin\n"))
3710 In this example, the resulting @file{/gnu/store/@dots{}-profile.sh} file
3711 will references @var{coreutils}, @var{grep}, and @var{sed}, thereby
3712 preventing them from being garbage-collected during its lifetime.
3715 @deffn {Scheme Procedure} mixed-text-file @var{name} @var{text} @dots{}
3716 Return an object representing store file @var{name} containing
3717 @var{text}. @var{text} is a sequence of strings and file-like objects,
3721 (mixed-text-file "profile"
3722 "export PATH=" coreutils "/bin:" grep "/bin")
3725 This is the declarative counterpart of @code{text-file*}.
3728 Of course, in addition to gexps embedded in ``host'' code, there are
3729 also modules containing build tools. To make it clear that they are
3730 meant to be used in the build stratum, these modules are kept in the
3731 @code{(guix build @dots{})} name space.
3733 @cindex lowering, of high-level objects in gexps
3734 Internally, high-level objects are @dfn{lowered}, using their compiler,
3735 to either derivations or store items. For instance, lowering a package
3736 yields a derivation, and lowering a @code{plain-file} yields a store
3737 item. This is achieved using the @code{lower-object} monadic procedure.
3739 @deffn {Monadic Procedure} lower-object @var{obj} [@var{system}] @
3741 Return as a value in @var{%store-monad} the derivation or store item
3742 corresponding to @var{obj} for @var{system}, cross-compiling for
3743 @var{target} if @var{target} is true. @var{obj} must be an object that
3744 has an associated gexp compiler, such as a @code{<package>}.
3748 @c *********************************************************************
3752 This section describes tools primarily targeted at developers and users
3753 who write new package definitions. They complement the Scheme
3754 programming interface of Guix in a convenient way.
3757 * Invoking guix build:: Building packages from the command line.
3758 * Invoking guix edit:: Editing package definitions.
3759 * Invoking guix download:: Downloading a file and printing its hash.
3760 * Invoking guix hash:: Computing the cryptographic hash of a file.
3761 * Invoking guix import:: Importing package definitions.
3762 * Invoking guix refresh:: Updating package definitions.
3763 * Invoking guix lint:: Finding errors in package definitions.
3764 * Invoking guix size:: Profiling disk usage.
3765 * Invoking guix graph:: Visualizing the graph of packages.
3766 * Invoking guix environment:: Setting up development environments.
3767 * Invoking guix publish:: Sharing substitutes.
3768 * Invoking guix challenge:: Challenging substitute servers.
3769 * Invoking guix container:: Process isolation.
3772 @node Invoking guix build
3773 @section Invoking @command{guix build}
3775 The @command{guix build} command builds packages or derivations and
3776 their dependencies, and prints the resulting store paths. Note that it
3777 does not modify the user's profile---this is the job of the
3778 @command{guix package} command (@pxref{Invoking guix package}). Thus,
3779 it is mainly useful for distribution developers.
3781 The general syntax is:
3784 guix build @var{options} @var{package-or-derivation}@dots{}
3787 As an example, the following command builds the latest version of Emacs
3788 and of Guile, displays their build logs, and finally displays the
3789 resulting directories:
3792 guix build emacs guile
3795 Similarly, the following command builds all the available packages:
3798 guix build --keep-going \
3799 `guix package -A | cut -f1,2 --output-delimiter=@@`
3802 @var{package-or-derivation} may be either the name of a package found in
3803 the software distribution such as @code{coreutils} or
3804 @code{coreutils-8.20}, or a derivation such as
3805 @file{/gnu/store/@dots{}-coreutils-8.19.drv}. In the former case, a
3806 package with the corresponding name (and optionally version) is searched
3807 for among the GNU distribution modules (@pxref{Package Modules}).
3809 Alternatively, the @code{--expression} option may be used to specify a
3810 Scheme expression that evaluates to a package; this is useful when
3811 disambiguation among several same-named packages or package variants is
3814 There may be zero or more @var{options}. The available options are
3815 described in the subsections below.
3818 * Common Build Options:: Build options for most commands.
3819 * Package Transformation Options:: Creating variants of packages.
3820 * Additional Build Options:: Options specific to 'guix build'.
3823 @node Common Build Options
3824 @subsection Common Build Options
3826 A number of options that control the build process are common to
3827 @command{guix build} and other commands that can spawn builds, such as
3828 @command{guix package} or @command{guix archive}. These are the
3833 @item --load-path=@var{directory}
3834 @itemx -L @var{directory}
3835 Add @var{directory} to the front of the package module search path
3836 (@pxref{Package Modules}).
3838 This allows users to define their own packages and make them visible to
3839 the command-line tools.
3843 Keep the build tree of failed builds. Thus, if a build fail, its build
3844 tree is kept under @file{/tmp}, in a directory whose name is shown at
3845 the end of the build log. This is useful when debugging build issues.
3849 Keep going when some of the derivations fail to build; return only once
3850 all the builds have either completed or failed.
3852 The default behavior is to stop as soon as one of the specified
3853 derivations has failed.
3857 Do not build the derivations.
3860 When substituting a pre-built binary fails, fall back to building
3863 @item --substitute-urls=@var{urls}
3864 @anchor{client-substitute-urls}
3865 Consider @var{urls} the whitespace-separated list of substitute source
3866 URLs, overriding the default list of URLs of @command{guix-daemon}
3867 (@pxref{daemon-substitute-urls,, @command{guix-daemon} URLs}).
3869 This means that substitutes may be downloaded from @var{urls}, provided
3870 they are signed by a key authorized by the system administrator
3871 (@pxref{Substitutes}).
3873 @item --no-substitutes
3874 Do not use substitutes for build products. That is, always build things
3875 locally instead of allowing downloads of pre-built binaries
3876 (@pxref{Substitutes}).
3878 @item --rounds=@var{n}
3879 Build each derivation @var{n} times in a row, and raise an error if
3880 consecutive build results are not bit-for-bit identical.
3882 This is a useful way to detect non-deterministic builds processes.
3883 Non-deterministic build processes are a problem because they make it
3884 practically impossible for users to @emph{verify} whether third-party
3885 binaries are genuine. @xref{Invoking guix challenge}, for more.
3887 Note that, currently, the differing build results are not kept around,
3888 so you will have to manually investigate in case of an error---e.g., by
3889 stashing one of the build results with @code{guix archive --export},
3890 then rebuilding, and finally comparing the two results.
3892 @item --no-build-hook
3893 Do not attempt to offload builds @i{via} the daemon's ``build hook''
3894 (@pxref{Daemon Offload Setup}). That is, always build things locally
3895 instead of offloading builds to remote machines.
3897 @item --max-silent-time=@var{seconds}
3898 When the build or substitution process remains silent for more than
3899 @var{seconds}, terminate it and report a build failure.
3901 @item --timeout=@var{seconds}
3902 Likewise, when the build or substitution process lasts for more than
3903 @var{seconds}, terminate it and report a build failure.
3905 By default there is no timeout. This behavior can be restored with
3908 @item --verbosity=@var{level}
3909 Use the given verbosity level. @var{level} must be an integer between 0
3910 and 5; higher means more verbose output. Setting a level of 4 or more
3911 may be helpful when debugging setup issues with the build daemon.
3913 @item --cores=@var{n}
3915 Allow the use of up to @var{n} CPU cores for the build. The special
3916 value @code{0} means to use as many CPU cores as available.
3918 @item --max-jobs=@var{n}
3920 Allow at most @var{n} build jobs in parallel. @xref{Invoking
3921 guix-daemon, @code{--max-jobs}}, for details about this option and the
3922 equivalent @command{guix-daemon} option.
3926 Behind the scenes, @command{guix build} is essentially an interface to
3927 the @code{package-derivation} procedure of the @code{(guix packages)}
3928 module, and to the @code{build-derivations} procedure of the @code{(guix
3929 derivations)} module.
3931 In addition to options explicitly passed on the command line,
3932 @command{guix build} and other @command{guix} commands that support
3933 building honor the @code{GUIX_BUILD_OPTIONS} environment variable.
3935 @defvr {Environment Variable} GUIX_BUILD_OPTIONS
3936 Users can define this variable to a list of command line options that
3937 will automatically be used by @command{guix build} and other
3938 @command{guix} commands that can perform builds, as in the example
3942 $ export GUIX_BUILD_OPTIONS="--no-substitutes -c 2 -L /foo/bar"
3945 These options are parsed independently, and the result is appended to
3946 the parsed command-line options.
3950 @node Package Transformation Options
3951 @subsection Package Transformation Options
3953 @cindex package variants
3954 Another set of command-line options supported by @command{guix build}
3955 and also @command{guix package} are @dfn{package transformation
3956 options}. These are options that allow you to define @dfn{package
3957 variants}---for instance, packages built from different source code.
3958 This is a convenient way to create customized packages on the fly
3959 without having to type in the definitions of package variants
3960 (@pxref{Defining Packages}).
3964 @item --with-source=@var{source}
3965 Use @var{source} as the source of the corresponding package.
3966 @var{source} must be a file name or a URL, as for @command{guix
3967 download} (@pxref{Invoking guix download}).
3969 The ``corresponding package'' is taken to be one specified on the
3970 command line whose name matches the base of @var{source}---e.g., if
3971 @var{source} is @code{/src/guile-2.0.10.tar.gz}, the corresponding
3972 package is @code{guile}. Likewise, the version string is inferred from
3973 @var{source}; in the previous example, it's @code{2.0.10}.
3975 This option allows users to try out versions of packages other than the
3976 one provided by the distribution. The example below downloads
3977 @file{ed-1.7.tar.gz} from a GNU mirror and uses that as the source for
3978 the @code{ed} package:
3981 guix build ed --with-source=mirror://gnu/ed/ed-1.7.tar.gz
3984 As a developer, @code{--with-source} makes it easy to test release
3988 guix build guile --with-source=../guile-2.0.9.219-e1bb7.tar.xz
3991 @dots{} or to build from a checkout in a pristine environment:
3994 $ git clone git://git.sv.gnu.org/guix.git
3995 $ guix build guix --with-source=./guix
3998 @item --with-input=@var{package}=@var{replacement}
3999 Replace dependency on @var{package} by a dependency on
4000 @var{replacement}. @var{package} must be a package name, and
4001 @var{replacement} must be a package specification such as @code{guile}
4002 or @code{guile@@1.8}.
4004 For instance, the following command builds Guix but replaces its
4005 dependency on the current stable version of Guile with a dependency on
4006 the development version of Guile, @code{guile-next}:
4009 guix build --with-input=guile=guile-next guix
4012 This is a recursive, deep replacement. So in this example, both
4013 @code{guix} and its dependency @code{guile-json} (which also depends on
4014 @code{guile}) get rebuilt against @code{guile-next}.
4016 However, implicit inputs are left unchanged.
4019 @node Additional Build Options
4020 @subsection Additional Build Options
4022 The command-line options presented below are specific to @command{guix
4027 @item --file=@var{file}
4028 @itemx -f @var{file}
4030 Build the package or derivation that the code within @var{file}
4033 As an example, @var{file} might contain a package definition like this
4034 (@pxref{Defining Packages}):
4037 @verbatiminclude package-hello.scm
4040 @item --expression=@var{expr}
4041 @itemx -e @var{expr}
4042 Build the package or derivation @var{expr} evaluates to.
4044 For example, @var{expr} may be @code{(@@ (gnu packages guile)
4045 guile-1.8)}, which unambiguously designates this specific variant of
4046 version 1.8 of Guile.
4048 Alternately, @var{expr} may be a G-expression, in which case it is used
4049 as a build program passed to @code{gexp->derivation}
4050 (@pxref{G-Expressions}).
4052 Lastly, @var{expr} may refer to a zero-argument monadic procedure
4053 (@pxref{The Store Monad}). The procedure must return a derivation as a
4054 monadic value, which is then passed through @code{run-with-store}.
4058 Build the packages' source derivations, rather than the packages
4061 For instance, @code{guix build -S gcc} returns something like
4062 @file{/gnu/store/@dots{}-gcc-4.7.2.tar.bz2}, which is GCC's source tarball.
4064 The returned source tarball is the result of applying any patches and
4065 code snippets specified in the package's @code{origin} (@pxref{Defining
4069 Fetch and return the source of @var{package-or-derivation} and all their
4070 dependencies, recursively. This is a handy way to obtain a local copy
4071 of all the source code needed to build @var{packages}, allowing you to
4072 eventually build them even without network access. It is an extension
4073 of the @code{--source} option and can accept one of the following
4074 optional argument values:
4078 This value causes the @code{--sources} option to behave in the same way
4079 as the @code{--source} option.
4082 Build all packages' source derivations, including any source that might
4083 be listed as @code{inputs}. This is the default value.
4086 $ guix build --sources tzdata
4087 The following derivations will be built:
4088 /gnu/store/@dots{}-tzdata2015b.tar.gz.drv
4089 /gnu/store/@dots{}-tzcode2015b.tar.gz.drv
4093 Build all packages' source derivations, as well as all source
4094 derivations for packages' transitive inputs. This can be used e.g. to
4095 prefetch package source for later offline building.
4098 $ guix build --sources=transitive tzdata
4099 The following derivations will be built:
4100 /gnu/store/@dots{}-tzcode2015b.tar.gz.drv
4101 /gnu/store/@dots{}-findutils-4.4.2.tar.xz.drv
4102 /gnu/store/@dots{}-grep-2.21.tar.xz.drv
4103 /gnu/store/@dots{}-coreutils-8.23.tar.xz.drv
4104 /gnu/store/@dots{}-make-4.1.tar.xz.drv
4105 /gnu/store/@dots{}-bash-4.3.tar.xz.drv
4111 @item --system=@var{system}
4112 @itemx -s @var{system}
4113 Attempt to build for @var{system}---e.g., @code{i686-linux}---instead of
4114 the host's system type.
4116 An example use of this is on Linux-based systems, which can emulate
4117 different personalities. For instance, passing
4118 @code{--system=i686-linux} on an @code{x86_64-linux} system allows users
4119 to build packages in a complete 32-bit environment.
4121 @item --target=@var{triplet}
4122 @cindex cross-compilation
4123 Cross-build for @var{triplet}, which must be a valid GNU triplet, such
4124 as @code{"mips64el-linux-gnu"} (@pxref{Configuration Names, GNU
4125 configuration triplets,, configure, GNU Configure and Build System}).
4127 @anchor{build-check}
4129 @cindex determinism, checking
4130 @cindex reproducibility, checking
4131 Rebuild @var{package-or-derivation}, which are already available in the
4132 store, and raise an error if the build results are not bit-for-bit
4135 This mechanism allows you to check whether previously-installed
4136 substitutes are genuine (@pxref{Substitutes}), or whether a package's
4137 build result is deterministic. @xref{Invoking guix challenge}, for more
4138 background information and tools.
4141 Do not ``graft'' packages. In practice, this means that package updates
4142 available as grafts are not applied. @xref{Security Updates}, for more
4143 information on grafts.
4147 Return the derivation paths, not the output paths, of the given
4150 @item --root=@var{file}
4151 @itemx -r @var{file}
4152 Make @var{file} a symlink to the result, and register it as a garbage
4156 Return the build log file names or URLs for the given
4157 @var{package-or-derivation}s, or raise an error if build logs are
4160 This works regardless of how packages or derivations are specified. For
4161 instance, the following invocations are equivalent:
4164 guix build --log-file `guix build -d guile`
4165 guix build --log-file `guix build guile`
4166 guix build --log-file guile
4167 guix build --log-file -e '(@@ (gnu packages guile) guile-2.0)'
4170 If a log is unavailable locally, and unless @code{--no-substitutes} is
4171 passed, the command looks for a corresponding log on one of the
4172 substitute servers (as specified with @code{--substitute-urls}.)
4174 So for instance, let's say you want to see the build log of GDB on MIPS
4175 but you're actually on an @code{x86_64} machine:
4178 $ guix build --log-file gdb -s mips64el-linux
4179 http://hydra.gnu.org/log/@dots{}-gdb-7.10
4182 You can freely access a huge library of build logs!
4186 @node Invoking guix edit
4187 @section Invoking @command{guix edit}
4189 @cindex package definition, editing
4190 So many packages, so many source files! The @command{guix edit} command
4191 facilitates the life of packagers by pointing their editor at the source
4192 file containing the definition of the specified packages. For instance:
4195 guix edit gcc-4.8 vim
4199 launches the program specified in the @code{VISUAL} or in the
4200 @code{EDITOR} environment variable to edit the recipe of GCC@tie{}4.8.4
4203 If you are using Emacs, note that the Emacs user interface provides
4204 similar functionality in the ``package info'' and ``package list''
4205 buffers created by @kbd{M-x guix-search-by-name} and similar commands
4206 (@pxref{Emacs Commands}).
4209 @node Invoking guix download
4210 @section Invoking @command{guix download}
4212 When writing a package definition, developers typically need to download
4213 the package's source tarball, compute its SHA256 hash, and write that
4214 hash in the package definition (@pxref{Defining Packages}). The
4215 @command{guix download} tool helps with this task: it downloads a file
4216 from the given URI, adds it to the store, and prints both its file name
4217 in the store and its SHA256 hash.
4219 The fact that the downloaded file is added to the store saves bandwidth:
4220 when the developer eventually tries to build the newly defined package
4221 with @command{guix build}, the source tarball will not have to be
4222 downloaded again because it is already in the store. It is also a
4223 convenient way to temporarily stash files, which may be deleted
4224 eventually (@pxref{Invoking guix gc}).
4226 The @command{guix download} command supports the same URIs as used in
4227 package definitions. In particular, it supports @code{mirror://} URIs.
4228 @code{https} URIs (HTTP over TLS) are supported @emph{provided} the
4229 Guile bindings for GnuTLS are available in the user's environment; when
4230 they are not available, an error is raised. @xref{Guile Preparations,
4231 how to install the GnuTLS bindings for Guile,, gnutls-guile,
4232 GnuTLS-Guile}, for more information.
4234 The following option is available:
4237 @item --format=@var{fmt}
4239 Write the hash in the format specified by @var{fmt}. For more
4240 information on the valid values for @var{fmt}, @pxref{Invoking guix hash}.
4243 @node Invoking guix hash
4244 @section Invoking @command{guix hash}
4246 The @command{guix hash} command computes the SHA256 hash of a file.
4247 It is primarily a convenience tool for anyone contributing to the
4248 distribution: it computes the cryptographic hash of a file, which can be
4249 used in the definition of a package (@pxref{Defining Packages}).
4251 The general syntax is:
4254 guix hash @var{option} @var{file}
4257 @command{guix hash} has the following option:
4261 @item --format=@var{fmt}
4263 Write the hash in the format specified by @var{fmt}.
4265 Supported formats: @code{nix-base32}, @code{base32}, @code{base16}
4266 (@code{hex} and @code{hexadecimal} can be used as well).
4268 If the @option{--format} option is not specified, @command{guix hash}
4269 will output the hash in @code{nix-base32}. This representation is used
4270 in the definitions of packages.
4274 Compute the hash on @var{file} recursively.
4276 In this case, the hash is computed on an archive containing @var{file},
4277 including its children if it is a directory. Some of @var{file}'s
4278 meta-data is part of the archive; for instance, when @var{file} is a
4279 regular file, the hash is different depending on whether @var{file} is
4280 executable or not. Meta-data such as time stamps has no impact on the
4281 hash (@pxref{Invoking guix archive}).
4282 @c FIXME: Replace xref above with xref to an ``Archive'' section when
4287 @node Invoking guix import
4288 @section Invoking @command{guix import}
4290 @cindex importing packages
4291 @cindex package import
4292 @cindex package conversion
4293 The @command{guix import} command is useful for people willing to add a
4294 package to the distribution but who'd rather do as little work as
4295 possible to get there---a legitimate demand. The command knows of a few
4296 repositories from which it can ``import'' package meta-data. The result
4297 is a package definition, or a template thereof, in the format we know
4298 (@pxref{Defining Packages}).
4300 The general syntax is:
4303 guix import @var{importer} @var{options}@dots{}
4306 @var{importer} specifies the source from which to import package
4307 meta-data, and @var{options} specifies a package identifier and other
4308 options specific to @var{importer}. Currently, the available
4313 Import meta-data for the given GNU package. This provides a template
4314 for the latest version of that GNU package, including the hash of its
4315 source tarball, and its canonical synopsis and description.
4317 Additional information such as the package's dependencies and its
4318 license needs to be figured out manually.
4320 For example, the following command returns a package definition for
4324 guix import gnu hello
4327 Specific command-line options are:
4330 @item --key-download=@var{policy}
4331 As for @code{guix refresh}, specify the policy to handle missing OpenPGP
4332 keys when verifying the package's signature. @xref{Invoking guix
4333 refresh, @code{--key-download}}.
4338 Import meta-data from the @uref{https://pypi.python.org/, Python Package
4339 Index}@footnote{This functionality requires Guile-JSON to be installed.
4340 @xref{Requirements}.}. Information is taken from the JSON-formatted
4341 description available at @code{pypi.python.org} and usually includes all
4342 the relevant information, including package dependencies.
4344 The command below imports meta-data for the @code{itsdangerous} Python
4348 guix import pypi itsdangerous
4353 Import meta-data from @uref{https://rubygems.org/,
4354 RubyGems}@footnote{This functionality requires Guile-JSON to be
4355 installed. @xref{Requirements}.}. Information is taken from the
4356 JSON-formatted description available at @code{rubygems.org} and includes
4357 most relevant information, including runtime dependencies. There are
4358 some caveats, however. The meta-data doesn't distinguish between
4359 synopses and descriptions, so the same string is used for both fields.
4360 Additionally, the details of non-Ruby dependencies required to build
4361 native extensions is unavailable and left as an exercise to the
4364 The command below imports meta-data for the @code{rails} Ruby package:
4367 guix import gem rails
4372 Import meta-data from @uref{https://www.metacpan.org/, MetaCPAN}.
4373 Information is taken from the JSON-formatted meta-data provided through
4374 @uref{https://api.metacpan.org/, MetaCPAN's API} and includes most
4375 relevant information, such as module dependencies. License information
4376 should be checked closely. If Perl is available in the store, then the
4377 @code{corelist} utility will be used to filter core modules out of the
4378 list of dependencies.
4380 The command command below imports meta-data for the @code{Acme::Boolean}
4384 guix import cpan Acme::Boolean
4389 @cindex Bioconductor
4390 Import meta-data from @uref{http://cran.r-project.org/, CRAN}, the
4391 central repository for the @uref{http://r-project.org, GNU@tie{}R
4392 statistical and graphical environment}.
4394 Information is extracted from the package's @code{DESCRIPTION} file.
4396 The command command below imports meta-data for the @code{Cairo}
4400 guix import cran Cairo
4403 When @code{--archive=bioconductor} is added, meta-data is imported from
4404 @uref{http://www.bioconductor.org/, Bioconductor}, a repository of R
4405 packages for for the analysis and comprehension of high-throughput
4406 genomic data in bioinformatics.
4408 Information is extracted from a package's @code{DESCRIPTION} file
4409 published on the web interface of the Bioconductor SVN repository.
4411 The command command below imports meta-data for the @code{GenomicRanges}
4415 guix import cran --archive=bioconductor GenomicRanges
4419 Import meta-data from a local copy of the source of the
4420 @uref{http://nixos.org/nixpkgs/, Nixpkgs distribution}@footnote{This
4421 relies on the @command{nix-instantiate} command of
4422 @uref{http://nixos.org/nix/, Nix}.}. Package definitions in Nixpkgs are
4423 typically written in a mixture of Nix-language and Bash code. This
4424 command only imports the high-level package structure that is written in
4425 the Nix language. It normally includes all the basic fields of a
4428 When importing a GNU package, the synopsis and descriptions are replaced
4429 by their canonical upstream variant.
4431 Usually, you will first need to do:
4434 export NIX_REMOTE=daemon
4438 so that @command{nix-instantiate} does not try to open the Nix database.
4440 As an example, the command below imports the package definition of
4441 LibreOffice (more precisely, it imports the definition of the package
4442 bound to the @code{libreoffice} top-level attribute):
4445 guix import nix ~/path/to/nixpkgs libreoffice
4450 Import meta-data from Haskell community's central package archive
4451 @uref{https://hackage.haskell.org/, Hackage}. Information is taken from
4452 Cabal files and includes all the relevant information, including package
4455 Specific command-line options are:
4460 Read a Cabal file from the standard input.
4461 @item --no-test-dependencies
4463 Do not include dependencies required by the test suites only.
4464 @item --cabal-environment=@var{alist}
4465 @itemx -e @var{alist}
4466 @var{alist} is a Scheme alist defining the environment in which the
4467 Cabal conditionals are evaluated. The accepted keys are: @code{os},
4468 @code{arch}, @code{impl} and a string representing the name of a flag.
4469 The value associated with a flag has to be either the symbol
4470 @code{true} or @code{false}. The value associated with other keys
4471 has to conform to the Cabal file format definition. The default value
4472 associated with the keys @code{os}, @code{arch} and @code{impl} is
4473 @samp{linux}, @samp{x86_64} and @samp{ghc} respectively.
4476 The command below imports meta-data for the latest version of the
4477 @code{HTTP} Haskell package without including test dependencies and
4478 specifying the value of the flag @samp{network-uri} as @code{false}:
4481 guix import hackage -t -e "'((\"network-uri\" . false))" HTTP
4484 A specific package version may optionally be specified by following the
4485 package name by a hyphen and a version number as in the following example:
4488 guix import hackage mtl-2.1.3.1
4493 Import meta-data from an Emacs Lisp Package Archive (ELPA) package
4494 repository (@pxref{Packages,,, emacs, The GNU Emacs Manual}).
4496 Specific command-line options are:
4499 @item --archive=@var{repo}
4500 @itemx -a @var{repo}
4501 @var{repo} identifies the archive repository from which to retrieve the
4502 information. Currently the supported repositories and their identifiers
4506 @uref{http://elpa.gnu.org/packages, GNU}, selected by the @code{gnu}
4507 identifier. This is the default.
4510 @uref{http://stable.melpa.org/packages, MELPA-Stable}, selected by the
4511 @code{melpa-stable} identifier.
4514 @uref{http://melpa.org/packages, MELPA}, selected by the @code{melpa}
4520 The structure of the @command{guix import} code is modular. It would be
4521 useful to have more importers for other package formats, and your help
4522 is welcome here (@pxref{Contributing}).
4524 @node Invoking guix refresh
4525 @section Invoking @command{guix refresh}
4527 The primary audience of the @command{guix refresh} command is developers
4528 of the GNU software distribution. By default, it reports any packages
4529 provided by the distribution that are outdated compared to the latest
4530 upstream version, like this:
4534 gnu/packages/gettext.scm:29:13: gettext would be upgraded from 0.18.1.1 to 0.18.2.1
4535 gnu/packages/glib.scm:77:12: glib would be upgraded from 2.34.3 to 2.37.0
4538 It does so by browsing each package's FTP directory and determining the
4539 highest version number of the source tarballs therein. The command
4540 knows how to update specific types of packages: GNU packages, ELPA
4541 packages, etc.---see the documentation for @option{--type} below. The
4542 are many packages, though, for which it lacks a method to determine
4543 whether a new upstream release is available. However, the mechanism is
4544 extensible, so feel free to get in touch with us to add a new method!
4546 When passed @code{--update}, it modifies distribution source files to
4547 update the version numbers and source tarball hashes of those packages'
4548 recipes (@pxref{Defining Packages}). This is achieved by downloading
4549 each package's latest source tarball and its associated OpenPGP
4550 signature, authenticating the downloaded tarball against its signature
4551 using @command{gpg}, and finally computing its hash. When the public
4552 key used to sign the tarball is missing from the user's keyring, an
4553 attempt is made to automatically retrieve it from a public key server;
4554 when it's successful, the key is added to the user's keyring; otherwise,
4555 @command{guix refresh} reports an error.
4557 The following options are supported:
4561 @item --expression=@var{expr}
4562 @itemx -e @var{expr}
4563 Consider the package @var{expr} evaluates to.
4565 This is useful to precisely refer to a package, as in this example:
4568 guix refresh -l -e '(@@@@ (gnu packages commencement) glibc-final)'
4571 This command lists the dependents of the ``final'' libc (essentially all
4576 Update distribution source files (package recipes) in place. This is
4577 usually run from a checkout of the Guix source tree (@pxref{Running
4578 Guix Before It Is Installed}):
4581 $ ./pre-inst-env guix refresh -s non-core
4584 @xref{Defining Packages}, for more information on package definitions.
4586 @item --select=[@var{subset}]
4587 @itemx -s @var{subset}
4588 Select all the packages in @var{subset}, one of @code{core} or
4591 The @code{core} subset refers to all the packages at the core of the
4592 distribution---i.e., packages that are used to build ``everything
4593 else''. This includes GCC, libc, Binutils, Bash, etc. Usually,
4594 changing one of these packages in the distribution entails a rebuild of
4595 all the others. Thus, such updates are an inconvenience to users in
4596 terms of build time or bandwidth used to achieve the upgrade.
4598 The @code{non-core} subset refers to the remaining packages. It is
4599 typically useful in cases where an update of the core packages would be
4602 @item --type=@var{updater}
4603 @itemx -t @var{updater}
4604 Select only packages handled by @var{updater} (may be a comma-separated
4605 list of updaters). Currently, @var{updater} may be one of:
4609 the updater for GNU packages;
4611 the updater for GNOME packages;
4613 the updater for @uref{http://elpa.gnu.org/, ELPA} packages;
4615 the updater for @uref{http://cran.r-project.org/, CRAN} packages;
4617 the updater for @uref{http://www.bioconductor.org/, Bioconductor} R packages;
4619 the updater for @uref{https://pypi.python.org, PyPI} packages.
4622 For instance, the following commands only checks for updates of Emacs
4623 packages hosted at @code{elpa.gnu.org} and updates of CRAN packages:
4626 $ guix refresh --type=elpa,cran
4627 gnu/packages/statistics.scm:819:13: r-testthat would be upgraded from 0.10.0 to 0.11.0
4628 gnu/packages/emacs.scm:856:13: emacs-auctex would be upgraded from 11.88.6 to 11.88.9
4633 In addition, @command{guix refresh} can be passed one or more package
4634 names, as in this example:
4637 $ ./pre-inst-env guix refresh -u emacs idutils gcc-4.8.4
4641 The command above specifically updates the @code{emacs} and
4642 @code{idutils} packages. The @code{--select} option would have no
4643 effect in this case.
4645 When considering whether to upgrade a package, it is sometimes
4646 convenient to know which packages would be affected by the upgrade and
4647 should be checked for compatibility. For this the following option may
4648 be used when passing @command{guix refresh} one or more package names:
4652 @item --list-updaters
4654 List available updaters and exit (see @option{--type} above.)
4656 @item --list-dependent
4658 List top-level dependent packages that would need to be rebuilt as a
4659 result of upgrading one or more packages.
4663 Be aware that the @code{--list-dependent} option only
4664 @emph{approximates} the rebuilds that would be required as a result of
4665 an upgrade. More rebuilds might be required under some circumstances.
4668 $ guix refresh --list-dependent flex
4669 Building the following 120 packages would ensure 213 dependent packages are rebuilt:
4670 hop-2.4.0 geiser-0.4 notmuch-0.18 mu-0.9.9.5 cflow-1.4 idutils-4.6 @dots{}
4673 The command above lists a set of packages that could be built to check
4674 for compatibility with an upgraded @code{flex} package.
4676 The following options can be used to customize GnuPG operation:
4680 @item --gpg=@var{command}
4681 Use @var{command} as the GnuPG 2.x command. @var{command} is searched
4682 for in @code{$PATH}.
4684 @item --key-download=@var{policy}
4685 Handle missing OpenPGP keys according to @var{policy}, which may be one
4690 Always download missing OpenPGP keys from the key server, and add them
4691 to the user's GnuPG keyring.
4694 Never try to download missing OpenPGP keys. Instead just bail out.
4697 When a package signed with an unknown OpenPGP key is encountered, ask
4698 the user whether to download it or not. This is the default behavior.
4701 @item --key-server=@var{host}
4702 Use @var{host} as the OpenPGP key server when importing a public key.
4706 @node Invoking guix lint
4707 @section Invoking @command{guix lint}
4708 The @command{guix lint} is meant to help package developers avoid common
4709 errors and use a consistent style. It runs a number of checks on a
4710 given set of packages in order to find common mistakes in their
4711 definitions. Available @dfn{checkers} include (see
4712 @code{--list-checkers} for a complete list):
4717 Validate certain typographical and stylistic rules about package
4718 descriptions and synopses.
4720 @item inputs-should-be-native
4721 Identify inputs that should most likely be native inputs.
4725 @itemx source-file-name
4726 Probe @code{home-page} and @code{source} URLs and report those that are
4727 invalid. Check that the source file name is meaningful, e.g. is not
4728 just a version number or ``git-checkout'', and should not have a
4729 @code{file-name} declared (@pxref{origin Reference}).
4732 Report known vulnerabilities found in the Common Vulnerabilities and
4733 Exposures (CVE) database
4734 @uref{https://nvd.nist.gov/download.cfm#CVE_FEED, published by the US
4738 Warn about obvious source code formatting issues: trailing white space,
4739 use of tabulations, etc.
4742 The general syntax is:
4745 guix lint @var{options} @var{package}@dots{}
4748 If no package is given on the command line, then all packages are checked.
4749 The @var{options} may be zero or more of the following:
4755 Only enable the checkers specified in a comma-separated list using the
4756 names returned by @code{--list-checkers}.
4758 @item --list-checkers
4760 List and describe all the available checkers that will be run on packages
4765 @node Invoking guix size
4766 @section Invoking @command{guix size}
4768 The @command{guix size} command helps package developers profile the
4769 disk usage of packages. It is easy to overlook the impact of an
4770 additional dependency added to a package, or the impact of using a
4771 single output for a package that could easily be split (@pxref{Packages
4772 with Multiple Outputs}). These are the typical issues that
4773 @command{guix size} can highlight.
4775 The command can be passed a package specification such as @code{gcc-4.8}
4776 or @code{guile:debug}, or a file name in the store. Consider this
4780 $ guix size coreutils
4781 store item total self
4782 /gnu/store/@dots{}-coreutils-8.23 70.0 13.9 19.8%
4783 /gnu/store/@dots{}-gmp-6.0.0a 55.3 2.5 3.6%
4784 /gnu/store/@dots{}-acl-2.2.52 53.7 0.5 0.7%
4785 /gnu/store/@dots{}-attr-2.4.46 53.2 0.3 0.5%
4786 /gnu/store/@dots{}-gcc-4.8.4-lib 52.9 15.7 22.4%
4787 /gnu/store/@dots{}-glibc-2.21 37.2 37.2 53.1%
4791 The store items listed here constitute the @dfn{transitive closure} of
4792 Coreutils---i.e., Coreutils and all its dependencies, recursively---as
4793 would be returned by:
4796 $ guix gc -R /gnu/store/@dots{}-coreutils-8.23
4799 Here the output shows 3 columns next to store items. The first column,
4800 labeled ``total'', shows the size in mebibytes (MiB) of the closure of
4801 the store item---that is, its own size plus the size of all its
4802 dependencies. The next column, labeled ``self'', shows the size of the
4803 item itself. The last column shows the ratio of the item's size to the
4804 space occupied by all the items listed here.
4806 In this example, we see that the closure of Coreutils weighs in at
4807 70@tie{}MiB, half of which is taken by libc. (That libc represents a
4808 large fraction of the closure is not a problem @i{per se} because it is
4809 always available on the system anyway.)
4811 When the package passed to @command{guix size} is available in the
4812 store, @command{guix size} queries the daemon to determine its
4813 dependencies, and measures its size in the store, similar to @command{du
4814 -ms --apparent-size} (@pxref{du invocation,,, coreutils, GNU
4817 When the given package is @emph{not} in the store, @command{guix size}
4818 reports information based on information about the available substitutes
4819 (@pxref{Substitutes}). This allows it to profile disk usage of store
4820 items that are not even on disk, only available remotely.
4822 The available options are:
4826 @item --substitute-urls=@var{urls}
4827 Use substitute information from @var{urls}.
4828 @xref{client-substitute-urls, the same option for @code{guix build}}.
4830 @item --map-file=@var{file}
4831 Write to @var{file} a graphical map of disk usage as a PNG file.
4833 For the example above, the map looks like this:
4835 @image{images/coreutils-size-map,5in,, map of Coreutils disk usage
4836 produced by @command{guix size}}
4838 This option requires that
4839 @uref{http://wingolog.org/software/guile-charting/, Guile-Charting} be
4840 installed and visible in Guile's module search path. When that is not
4841 the case, @command{guix size} fails as it tries to load it.
4843 @item --system=@var{system}
4844 @itemx -s @var{system}
4845 Consider packages for @var{system}---e.g., @code{x86_64-linux}.
4849 @node Invoking guix graph
4850 @section Invoking @command{guix graph}
4853 Packages and their dependencies form a @dfn{graph}, specifically a
4854 directed acyclic graph (DAG). It can quickly become difficult to have a
4855 mental model of the package DAG, so the @command{guix graph} command is
4856 here to provide a visual representation of the DAG. @command{guix
4857 graph} emits a DAG representation in the input format of
4858 @uref{http://www.graphviz.org/, Graphviz}, so its output can be passed
4859 directly to Graphviz's @command{dot} command, for instance. The general
4863 guix graph @var{options} @var{package}@dots{}
4866 For example, the following command generates a PDF file representing the
4867 package DAG for the GNU@tie{}Core Utilities, showing its build-time
4871 guix graph coreutils | dot -Tpdf > dag.pdf
4874 The output looks like this:
4876 @image{images/coreutils-graph,2in,,Dependency graph of the GNU Coreutils}
4878 Nice little graph, no?
4880 But there's more than one graph! The one above is concise: it's the
4881 graph of package objects, omitting implicit inputs such as GCC, libc,
4882 grep, etc. It's often useful to have such a concise graph, but
4883 sometimes you want to see more details. @command{guix graph} supports
4884 several types of graphs, allowing you to choose the level of details:
4888 This is the default type, the one we used above. It shows the DAG of
4889 package objects, excluding implicit dependencies. It is concise, but
4890 filters out many details.
4893 This is the package DAG, @emph{including} implicit inputs.
4895 For instance, the following command:
4898 guix graph --type=bag-emerged coreutils | dot -Tpdf > dag.pdf
4901 ... yields this bigger graph:
4903 @image{images/coreutils-bag-graph,,5in,Detailed dependency graph of the GNU Coreutils}
4905 At the bottom of the graph, we see all the implicit inputs of
4906 @var{gnu-build-system} (@pxref{Build Systems, @code{gnu-build-system}}).
4908 Now, note that the dependencies of those implicit inputs---that is, the
4909 @dfn{bootstrap dependencies} (@pxref{Bootstrapping})---are not shown
4910 here, for conciseness.
4913 Similar to @code{bag-emerged}, but this time including all the bootstrap
4916 @item bag-with-origins
4917 Similar to @code{bag}, but also showing origins and their dependencies.
4920 This is the most detailed representation: It shows the DAG of
4921 derivations (@pxref{Derivations}) and plain store items. Compared to
4922 the above representation, many additional nodes are visible, including
4923 builds scripts, patches, Guile modules, etc.
4927 All the above types correspond to @emph{build-time dependencies}. The
4928 following graph type represents the @emph{run-time dependencies}:
4932 This is the graph of @dfn{references} of a package output, as returned
4933 by @command{guix gc --references} (@pxref{Invoking guix gc}).
4935 If the given package output is not available in the store, @command{guix
4936 graph} attempts to obtain dependency information from substitutes.
4939 The available options are the following:
4942 @item --type=@var{type}
4943 @itemx -t @var{type}
4944 Produce a graph output of @var{type}, where @var{type} must be one of
4945 the values listed above.
4948 List the supported graph types.
4950 @item --expression=@var{expr}
4951 @itemx -e @var{expr}
4952 Consider the package @var{expr} evaluates to.
4954 This is useful to precisely refer to a package, as in this example:
4957 guix graph -e '(@@@@ (gnu packages commencement) gnu-make-final)'
4962 @node Invoking guix environment
4963 @section Invoking @command{guix environment}
4965 @cindex reproducible build environments
4966 @cindex development environments
4967 The purpose of @command{guix environment} is to assist hackers in
4968 creating reproducible development environments without polluting their
4969 package profile. The @command{guix environment} tool takes one or more
4970 packages, builds all of the necessary inputs, and creates a shell
4971 environment to use them.
4973 The general syntax is:
4976 guix environment @var{options} @var{package}@dots{}
4979 The following example spawns a new shell set up for the development of
4983 guix environment guile
4986 If the specified packages are not built yet, @command{guix environment}
4987 automatically builds them. The new shell's environment is an augmented
4988 version of the environment that @command{guix environment} was run in.
4989 It contains the necessary search paths for building the given package
4990 added to the existing environment variables. To create a ``pure''
4991 environment in which the original environment variables have been unset,
4992 use the @code{--pure} option@footnote{Users sometimes wrongfully augment
4993 environment variables such as @code{PATH} in their @file{~/.bashrc}
4994 file. As a consequence, when @code{guix environment} launches it, Bash
4995 may read @file{~/.bashrc}, thereby introducing ``impurities'' in these
4996 environment variables. It is an error to define such environment
4997 variables in @file{.bashrc}; instead, they should be defined in
4998 @file{.bash_profile}, which is sourced only by log-in shells.
4999 @xref{Bash Startup Files,,, bash, The GNU Bash Reference Manual}, for
5000 details on Bash start-up files.}.
5002 @vindex GUIX_ENVIRONMENT
5003 @command{guix environment} defines the @code{GUIX_ENVIRONMENT}
5004 variable in the shell it spaws. This allows users to, say, define a
5005 specific prompt for development environments in their @file{.bashrc}
5006 (@pxref{Bash Startup Files,,, bash, The GNU Bash Reference Manual}):
5009 if [ -n "$GUIX_ENVIRONMENT" ]
5011 export PS1="\u@@\h \w [dev]\$ "
5015 Additionally, more than one package may be specified, in which case the
5016 union of the inputs for the given packages are used. For example, the
5017 command below spawns a shell where all of the dependencies of both Guile
5018 and Emacs are available:
5021 guix environment guile emacs
5024 Sometimes an interactive shell session is not desired. An arbitrary
5025 command may be invoked by placing the @code{--} token to separate the
5026 command from the rest of the arguments:
5029 guix environment guile -- make -j4
5032 In other situations, it is more convenient to specify the list of
5033 packages needed in the environment. For example, the following command
5034 runs @command{python} from an environment containing Python@tie{}2.7 and
5038 guix environment --ad-hoc python2-numpy python-2.7 -- python
5041 Furthermore, one might want the dependencies of a package and also some
5042 additional packages that are not build-time or runtime dependencies, but
5043 are useful when developing nonetheless. Because of this, the
5044 @code{--ad-hoc} flag is positional. Packages appearing before
5045 @code{--ad-hoc} are interpreted as packages whose dependencies will be
5046 added to the environment. Packages appearing after are interpreted as
5047 packages that will be added to the environment directly. For example,
5048 the following command creates a Guix development environment that
5049 additionally includes Git and strace:
5052 guix environment guix --ad-hoc git strace
5055 Sometimes it is desirable to isolate the environment as much as
5056 possible, for maximal purity and reproducibility. In particular, when
5057 using Guix on a host distro that is not GuixSD, it is desirable to
5058 prevent access to @file{/usr/bin} and other system-wide resources from
5059 the development environment. For example, the following command spawns
5060 a Guile REPL in a ``container'' where only the store and the current
5061 working directory are mounted:
5064 guix environment --ad-hoc --container guile -- guile
5068 The @code{--container} option requires Linux-libre 3.19 or newer.
5071 The available options are summarized below.
5074 @item --expression=@var{expr}
5075 @itemx -e @var{expr}
5076 Create an environment for the package or list of packages that
5077 @var{expr} evaluates to.
5079 For example, running:
5082 guix environment -e '(@@ (gnu packages maths) petsc-openmpi)'
5085 starts a shell with the environment for this specific variant of the
5091 guix environment --ad-hoc -e '(@@ (gnu) %base-packages)'
5094 starts a shell with all the GuixSD base packages available.
5096 @item --load=@var{file}
5097 @itemx -l @var{file}
5098 Create an environment for the package or list of packages that the code
5099 within @var{file} evaluates to.
5101 As an example, @var{file} might contain a definition like this
5102 (@pxref{Defining Packages}):
5105 @verbatiminclude environment-gdb.scm
5109 Include all specified packages in the resulting environment, as if an
5110 @i{ad hoc} package were defined with them as inputs. This option is
5111 useful for quickly creating an environment without having to write a
5112 package expression to contain the desired inputs.
5114 For instance, the command:
5117 guix environment --ad-hoc guile guile-sdl -- guile
5120 runs @command{guile} in an environment where Guile and Guile-SDL are
5123 Note that this example implicitly asks for the default output of
5124 @code{guile} and @code{guile-sdl} but it is possible to ask for a
5125 specific output---e.g., @code{glib:bin} asks for the @code{bin} output
5126 of @code{glib} (@pxref{Packages with Multiple Outputs}).
5128 This option may be composed with the default behavior of @command{guix
5129 environment}. Packages appearing before @code{--ad-hoc} are interpreted
5130 as packages whose dependencies will be added to the environment, the
5131 default behavior. Packages appearing after are interpreted as packages
5132 that will be added to the environment directly.
5135 Unset existing environment variables when building the new environment.
5136 This has the effect of creating an environment in which search paths
5137 only contain package inputs.
5139 @item --search-paths
5140 Display the environment variable definitions that make up the
5143 @item --system=@var{system}
5144 @itemx -s @var{system}
5145 Attempt to build for @var{system}---e.g., @code{i686-linux}.
5150 Run @var{command} within an isolated container. The current working
5151 directory outside the container is mapped inside the
5152 container. Additionally, the spawned process runs as the current user
5153 outside the container, but has root privileges in the context of the
5158 For containers, share the network namespace with the host system.
5159 Containers created without this flag only have access to the loopback
5162 @item --expose=@var{source}[=@var{target}]
5163 For containers, expose the file system @var{source} from the host system
5164 as the read-only file system @var{target} within the container. If
5165 @var{target} is not specified, @var{source} is used as the target mount
5166 point in the container.
5168 The example below spawns a Guile REPL in a container in which the user's
5169 home directory is accessible read-only via the @file{/exchange}
5173 guix environment --container --expose=$HOME=/exchange guile -- guile
5176 @item --share=@var{source}[=@var{target}]
5177 For containers, share the file system @var{source} from the host system
5178 as the writable file system @var{target} within the container. If
5179 @var{target} is not specified, @var{source} is used as the target mount
5180 point in the container.
5182 The example below spawns a Guile REPL in a container in which the user's
5183 home directory is accessible for both reading and writing via the
5184 @file{/exchange} directory:
5187 guix environment --container --share=$HOME=/exchange guile -- guile
5191 It also supports all of the common build options that @command{guix
5192 build} supports (@pxref{Common Build Options}).
5194 @node Invoking guix publish
5195 @section Invoking @command{guix publish}
5197 The purpose of @command{guix publish} is to enable users to easily share
5198 their store with others, which can then use it as a substitute server
5199 (@pxref{Substitutes}).
5201 When @command{guix publish} runs, it spawns an HTTP server which allows
5202 anyone with network access to obtain substitutes from it. This means
5203 that any machine running Guix can also act as if it were a build farm,
5204 since the HTTP interface is compatible with Hydra, the software behind
5205 the @code{hydra.gnu.org} build farm.
5207 For security, each substitute is signed, allowing recipients to check
5208 their authenticity and integrity (@pxref{Substitutes}). Because
5209 @command{guix publish} uses the system's signing key, which is only
5210 readable by the system administrator, it must be started as root; the
5211 @code{--user} option makes it drop root privileges early on.
5213 The signing key pair must be generated before @command{guix publish} is
5214 launched, using @command{guix archive --generate-key} (@pxref{Invoking
5217 The general syntax is:
5220 guix publish @var{options}@dots{}
5223 Running @command{guix publish} without any additional arguments will
5224 spawn an HTTP server on port 8080:
5230 Once a publishing server has been authorized (@pxref{Invoking guix
5231 archive}), the daemon may download substitutes from it:
5234 guix-daemon --substitute-urls=http://example.org:8080
5237 The following options are available:
5240 @item --port=@var{port}
5241 @itemx -p @var{port}
5242 Listen for HTTP requests on @var{port}.
5244 @item --listen=@var{host}
5245 Listen on the network interface for @var{host}. The default is to
5246 accept connections from any interface.
5248 @item --user=@var{user}
5249 @itemx -u @var{user}
5250 Change privileges to @var{user} as soon as possible---i.e., once the
5251 server socket is open and the signing key has been read.
5253 @item --repl[=@var{port}]
5254 @itemx -r [@var{port}]
5255 Spawn a Guile REPL server (@pxref{REPL Servers,,, guile, GNU Guile
5256 Reference Manual}) on @var{port} (37146 by default). This is used
5257 primarily for debugging a running @command{guix publish} server.
5260 Enabling @command{guix publish} on a GuixSD system is a one-liner: just
5261 add a call to @code{guix-publish-service} in the @code{services} field
5262 of the @code{operating-system} declaration (@pxref{guix-publish-service,
5263 @code{guix-publish-service}}).
5266 @node Invoking guix challenge
5267 @section Invoking @command{guix challenge}
5269 @cindex reproducible builds
5270 @cindex verifiable builds
5272 Do the binaries provided by this server really correspond to the source
5273 code it claims to build? Is this package's build process deterministic?
5274 These are the questions the @command{guix challenge} command attempts to
5277 The former is obviously an important question: Before using a substitute
5278 server (@pxref{Substitutes}), you'd rather @emph{verify} that it
5279 provides the right binaries, and thus @emph{challenge} it. The latter
5280 is what enables the former: If package builds are deterministic, then
5281 independent builds of the package should yield the exact same result,
5282 bit for bit; if a server provides a binary different from the one
5283 obtained locally, it may be either corrupt or malicious.
5285 We know that the hash that shows up in @file{/gnu/store} file names is
5286 the hash of all the inputs of the process that built the file or
5287 directory---compilers, libraries, build scripts,
5288 etc. (@pxref{Introduction}). Assuming deterministic build processes,
5289 one store file name should map to exactly one build output.
5290 @command{guix challenge} checks whether there is, indeed, a single
5291 mapping by comparing the build outputs of several independent builds of
5292 any given store item.
5294 The command's output looks like this:
5297 $ guix challenge --substitute-urls="http://hydra.gnu.org http://guix.example.org"
5298 updating list of substitutes from 'http://hydra.gnu.org'... 100.0%
5299 updating list of substitutes from 'http://guix.example.org'... 100.0%
5300 /gnu/store/@dots{}-openssl-1.0.2d contents differ:
5301 local hash: 0725l22r5jnzazaacncwsvp9kgf42266ayyp814v7djxs7nk963q
5302 http://hydra.gnu.org/nar/@dots{}-openssl-1.0.2d: 0725l22r5jnzazaacncwsvp9kgf42266ayyp814v7djxs7nk963q
5303 http://guix.example.org/nar/@dots{}-openssl-1.0.2d: 1zy4fmaaqcnjrzzajkdn3f5gmjk754b43qkq47llbyak9z0qjyim
5304 /gnu/store/@dots{}-git-2.5.0 contents differ:
5305 local hash: 00p3bmryhjxrhpn2gxs2fy0a15lnip05l97205pgbk5ra395hyha
5306 http://hydra.gnu.org/nar/@dots{}-git-2.5.0: 069nb85bv4d4a6slrwjdy8v1cn4cwspm3kdbmyb81d6zckj3nq9f
5307 http://guix.example.org/nar/@dots{}-git-2.5.0: 0mdqa9w1p6cmli6976v4wi0sw9r4p5prkj7lzfd1877wk11c9c73
5308 /gnu/store/@dots{}-pius-2.1.1 contents differ:
5309 local hash: 0k4v3m9z1zp8xzzizb7d8kjj72f9172xv078sq4wl73vnq9ig3ax
5310 http://hydra.gnu.org/nar/@dots{}-pius-2.1.1: 0k4v3m9z1zp8xzzizb7d8kjj72f9172xv078sq4wl73vnq9ig3ax
5311 http://guix.example.org/nar/@dots{}-pius-2.1.1: 1cy25x1a4fzq5rk0pmvc8xhwyffnqz95h2bpvqsz2mpvlbccy0gs
5315 In this example, @command{guix challenge} first scans the store to
5316 determine the set of locally-built derivations---as opposed to store
5317 items that were downloaded from a substitute server---and then queries
5318 all the substitute servers. It then reports those store items for which
5319 the servers obtained a result different from the local build.
5321 @cindex non-determinism, in package builds
5322 As an example, @code{guix.example.org} always gets a different answer.
5323 Conversely, @code{hydra.gnu.org} agrees with local builds, except in the
5324 case of Git. This might indicate that the build process of Git is
5325 non-deterministic, meaning that its output varies as a function of
5326 various things that Guix does not fully control, in spite of building
5327 packages in isolated environments (@pxref{Features}). Most common
5328 sources of non-determinism include the addition of timestamps in build
5329 results, the inclusion of random numbers, and directory listings sorted
5330 by inode number. See @uref{http://reproducible.debian.net/howto/}, for
5333 To find out what's wrong with this Git binary, we can do something along
5334 these lines (@pxref{Invoking guix archive}):
5337 $ wget -q -O - http://hydra.gnu.org/nar/@dots{}-git-2.5.0 \
5338 | guix archive -x /tmp/git
5339 $ diff -ur --no-dereference /gnu/store/@dots{}-git.2.5.0 /tmp/git
5342 This command shows the difference between the files resulting from the
5343 local build, and the files resulting from the build on
5344 @code{hydra.gnu.org} (@pxref{Overview, Comparing and Merging Files,,
5345 diffutils, Comparing and Merging Files}). The @command{diff} command
5346 works great for text files. When binary files differ, a better option
5347 is @uref{http://diffoscope.org/, Diffoscope}, a tool that helps
5348 visualize differences for all kinds of files.
5350 Once you've done that work, you can tell whether the differences are due
5351 to a non-deterministic build process or to a malicious server. We try
5352 hard to remove sources of non-determinism in packages to make it easier
5353 to verify substitutes, but of course, this is a process, one that
5354 involves not just Guix but a large part of the free software community.
5355 In the meantime, @command{guix challenge} is one tool to help address
5358 If you are writing packages for Guix, you are encouraged to check
5359 whether @code{hydra.gnu.org} and other substitute servers obtain the
5360 same build result as you did with:
5363 $ guix challenge @var{package}
5367 ... where @var{package} is a package specification such as
5368 @code{guile-2.0} or @code{glibc:debug}.
5370 The general syntax is:
5373 guix challenge @var{options} [@var{packages}@dots{}]
5376 The one option that matters is:
5380 @item --substitute-urls=@var{urls}
5381 Consider @var{urls} the whitespace-separated list of substitute source
5387 @node Invoking guix container
5388 @section Invoking @command{guix container}
5392 As of version @value{VERSION}, this tool is experimental. The interface
5393 is subject to radical change in the future.
5396 The purpose of @command{guix container} is to manipulate processes
5397 running within an isolated environment, commonly known as a
5398 ``container'', typically created by the @command{guix environment}
5399 (@pxref{Invoking guix environment}) and @command{guix system container}
5400 (@pxref{Invoking guix system}) commands.
5402 The general syntax is:
5405 guix container @var{action} @var{options}@dots{}
5408 @var{action} specifies the operation to perform with a container, and
5409 @var{options} specifies the context-specific arguments for the action.
5411 The following actions are available:
5415 Execute a command within the context of a running container.
5420 guix container exec @var{pid} @var{program} @var{arguments}@dots{}
5423 @var{pid} specifies the process ID of the running container.
5424 @var{program} specifies an executable file name within the container's
5425 root file system. @var{arguments} are the additional options that will
5426 be passed to @var{program}.
5428 The following command launches an interactive login shell inside a
5429 GuixSD container, started by @command{guix system container}, and whose
5433 guix container exec 9001 /run/current-system/profile/bin/bash --login
5436 Note that the @var{pid} cannot be the parent process of a container. It
5437 must be the container's PID 1 or one of its child processes.
5441 @c *********************************************************************
5442 @node GNU Distribution
5443 @chapter GNU Distribution
5445 @cindex Guix System Distribution
5447 Guix comes with a distribution of the GNU system consisting entirely of
5448 free software@footnote{The term ``free'' here refers to the
5449 @url{http://www.gnu.org/philosophy/free-sw.html,freedom provided to
5450 users of that software}.}. The
5451 distribution can be installed on its own (@pxref{System Installation}),
5452 but it is also possible to install Guix as a package manager on top of
5453 an installed GNU/Linux system (@pxref{Installation}). To distinguish
5454 between the two, we refer to the standalone distribution as the Guix
5455 System Distribution, or GuixSD.
5457 The distribution provides core GNU packages such as GNU libc, GCC, and
5458 Binutils, as well as many GNU and non-GNU applications. The complete
5459 list of available packages can be browsed
5460 @url{http://www.gnu.org/software/guix/packages,on-line} or by
5461 running @command{guix package} (@pxref{Invoking guix package}):
5464 guix package --list-available
5467 Our goal has been to provide a practical 100% free software distribution of
5468 Linux-based and other variants of GNU, with a focus on the promotion and
5469 tight integration of GNU components, and an emphasis on programs and
5470 tools that help users exert that freedom.
5472 Packages are currently available on the following platforms:
5477 Intel/AMD @code{x86_64} architecture, Linux-Libre kernel;
5480 Intel 32-bit architecture (IA32), Linux-Libre kernel;
5483 ARMv7-A architecture with hard float, Thumb-2 and NEON,
5484 using the EABI hard-float ABI, and Linux-Libre kernel.
5486 @item mips64el-linux
5487 little-endian 64-bit MIPS processors, specifically the Loongson series,
5488 n32 application binary interface (ABI), and Linux-Libre kernel.
5492 GuixSD itself is currently only available on @code{i686} and @code{x86_64}.
5495 For information on porting to other architectures or kernels,
5499 * System Installation:: Installing the whole operating system.
5500 * System Configuration:: Configuring the operating system.
5501 * Installing Debugging Files:: Feeding the debugger.
5502 * Security Updates:: Deploying security fixes quickly.
5503 * Package Modules:: Packages from the programmer's viewpoint.
5504 * Packaging Guidelines:: Growing the distribution.
5505 * Bootstrapping:: GNU/Linux built from scratch.
5506 * Porting:: Targeting another platform or kernel.
5509 Building this distribution is a cooperative effort, and you are invited
5510 to join! @xref{Contributing}, for information about how you can help.
5512 @node System Installation
5513 @section System Installation
5515 @cindex Guix System Distribution
5516 This section explains how to install the Guix System Distribution
5517 on a machine. The Guix package manager can
5518 also be installed on top of a running GNU/Linux system,
5519 @pxref{Installation}.
5522 @c This paragraph is for people reading this from tty2 of the
5523 @c installation image.
5524 You're reading this documentation with an Info reader. For details on
5525 how to use it, hit the @key{RET} key (``return'' or ``enter'') on the
5526 link that follows: @pxref{Help,,, info, Info: An Introduction}. Hit
5527 @kbd{l} afterwards to come back here.
5530 @subsection Limitations
5532 As of version @value{VERSION}, the Guix System Distribution (GuixSD) is
5533 not production-ready. It may contain bugs and lack important
5534 features. Thus, if you are looking for a stable production system that
5535 respects your freedom as a computer user, a good solution at this point
5536 is to consider @url{http://www.gnu.org/distros/free-distros.html, one of
5537 more established GNU/Linux distributions}. We hope you can soon switch
5538 to the GuixSD without fear, of course. In the meantime, you can
5539 also keep using your distribution and try out the package manager on top
5540 of it (@pxref{Installation}).
5542 Before you proceed with the installation, be aware of the following
5543 noteworthy limitations applicable to version @value{VERSION}:
5547 The installation process does not include a graphical user interface and
5548 requires familiarity with GNU/Linux (see the following subsections to
5549 get a feel of what that means.)
5552 The system does not yet provide full GNOME and KDE desktops. Xfce and
5553 Enlightenment are available though, if graphical desktop environments
5554 are your thing, as well as a number of X11 window managers.
5557 Support for the Logical Volume Manager (LVM) is missing.
5560 Few system services are currently supported out-of-the-box
5564 More than 2,000 packages are available, but you may
5565 occasionally find that a useful package is missing.
5568 You've been warned. But more than a disclaimer, this is an invitation
5569 to report issues (and success stories!), and join us in improving it.
5570 @xref{Contributing}, for more info.
5572 @subsection USB Stick Installation
5574 An installation image for USB sticks can be downloaded from
5575 @indicateurl{ftp://alpha.gnu.org/gnu/guix/guixsd-usb-install-@value{VERSION}.@var{system}.xz},
5576 where @var{system} is one of:
5580 for a GNU/Linux system on Intel/AMD-compatible 64-bit CPUs;
5583 for a 32-bit GNU/Linux system on Intel-compatible CPUs.
5586 This image contains a single partition with the tools necessary for an
5587 installation. It is meant to be copied @emph{as is} to a large-enough
5590 To copy the image to a USB stick, follow these steps:
5594 Decompress the image using the @command{xz} command:
5597 xz -d guixsd-usb-install-@value{VERSION}.@var{system}.xz
5601 Insert a USB stick of 1@tie{}GiB or more in your machine, and determine
5602 its device name. Assuming that USB stick is known as @file{/dev/sdX},
5603 copy the image with:
5606 dd if=guixsd-usb-install-@value{VERSION}.x86_64 of=/dev/sdX
5609 Access to @file{/dev/sdX} usually requires root privileges.
5612 Once this is done, you should be able to reboot the system and boot from
5613 the USB stick. The latter usually requires you to get in the BIOS' boot
5614 menu, where you can choose to boot from the USB stick.
5616 @subsection Preparing for Installation
5618 Once you have successfully booted the image on the USB stick, you should
5619 end up with a root prompt. Several console TTYs are configured and can
5620 be used to run commands as root. TTY2 shows this documentation,
5621 browsable using the Info reader commands (@pxref{Help,,, info, Info: An
5622 Introduction}). The installation system runs the GPM mouse daemon,
5623 which allows you to select text with the left mouse button and to paste
5624 it with the middle button.
5626 To install the system, you would:
5631 Configure the network, by running:
5634 ifconfig eno1 up && dhclient eno1
5637 to get an automatically assigned IP address from the wired
5638 network interface controller@footnote{
5639 @c http://cgit.freedesktop.org/systemd/systemd/tree/src/udev/udev-builtin-net_id.c#n20
5640 The name @code{eno1} is for the first on-board Ethernet controller. The
5641 interface name for an Ethernet controller that is in the first slot of
5642 the first PCI bus, for instance, would be @code{enp1s0}. Use
5643 @command{ifconfig -a} to list all the available network interfaces.},
5644 or using the @command{ifconfig} command.
5646 The system automatically loads drivers for your network interface
5649 Setting up network access is almost always a requirement because the
5650 image does not contain all the software and tools that may be needed.
5653 Unless this has already been done, you must partition, and then format
5654 the target partition.
5656 Preferably, assign partitions a label so that you can easily and
5657 reliably refer to them in @code{file-system} declarations (@pxref{File
5658 Systems}). This is typically done using the @code{-L} option of
5659 @command{mkfs.ext4} and related commands.
5661 Be sure that your partition labels match the value of their respective
5662 @code{device} fields in your @code{file-system} configuration, if your
5663 @code{file-system} configuration sets the value of @code{title} to
5664 @code{'label}, as do the example configurations found on the USB
5665 installation image under @file{/etc/configuration} (@pxref{Using the
5666 Configuration System}).
5668 @c FIXME: Uncomment this once GRUB fully supports encrypted roots.
5669 @c A typical command sequence may be:
5673 @c @dots{} Create partitions etc.@dots{}
5674 @c # cryptsetup luksFormat /dev/sdX1
5675 @c # cryptsetup open --type luks /dev/sdX1 my-partition
5676 @c # mkfs.ext4 -L my-root /dev/mapper/my-partition
5679 The installation image includes Parted (@pxref{Overview,,, parted, GNU
5680 Parted User Manual}), @command{fdisk}, Cryptsetup/LUKS for disk
5681 encryption, and e2fsprogs, the suite of tools to manipulate
5682 ext2/ext3/ext4 file systems.
5685 Once that is done, mount the target root partition under @file{/mnt}.
5688 Lastly, run @code{herd start cow-store /mnt}.
5690 This will make @file{/gnu/store} copy-on-write, such that packages added
5691 to it during the installation phase will be written to the target disk
5692 rather than kept in memory.
5697 @subsection Proceeding with the Installation
5699 With the target partitions ready, you now have to edit a file and
5700 provide the declaration of the operating system to be installed. To
5701 that end, the installation system comes with two text editors: GNU nano
5702 (@pxref{Top,,, nano, GNU nano Manual}), and GNU Zile, an Emacs clone.
5703 It is better to store that file on the target root file system, say, as
5704 @file{/mnt/etc/config.scm}.
5706 @xref{Using the Configuration System}, for examples of operating system
5707 configurations. These examples are available under
5708 @file{/etc/configuration} in the installation image, so you can copy
5709 them and use them as a starting point for your own configuration.
5711 Once you are done preparing the configuration file, the new system must
5712 be initialized (remember that the target root file system is mounted
5716 guix system init /mnt/etc/config.scm /mnt
5720 This will copy all the necessary files, and install GRUB on
5721 @file{/dev/sdX}, unless you pass the @option{--no-grub} option. For
5722 more information, @pxref{Invoking guix system}. This command may trigger
5723 downloads or builds of missing packages, which can take some time.
5725 Once that command has completed---and hopefully succeeded!---you can run
5726 @command{reboot} and boot into the new system. The @code{root} password
5727 in the new system is initially empty; other users' passwords need to be
5728 initialized by running the @command{passwd} command as @code{root},
5729 unless your configuration specifies otherwise
5730 (@pxref{user-account-password, user account passwords}).
5732 Join us on @code{#guix} on the Freenode IRC network or on
5733 @file{guix-devel@@gnu.org} to share your experience---good or not so
5736 @subsection Building the Installation Image
5738 The installation image described above was built using the @command{guix
5739 system} command, specifically:
5742 guix system disk-image --image-size=850MiB gnu/system/install.scm
5745 @xref{Invoking guix system}, for more information. See
5746 @file{gnu/system/install.scm} in the source tree for more information
5747 about the installation image.
5749 @node System Configuration
5750 @section System Configuration
5752 @cindex system configuration
5753 The Guix System Distribution supports a consistent whole-system configuration
5754 mechanism. By that we mean that all aspects of the global system
5755 configuration---such as the available system services, timezone and
5756 locale settings, user accounts---are declared in a single place. Such
5757 a @dfn{system configuration} can be @dfn{instantiated}---i.e., effected.
5759 One of the advantages of putting all the system configuration under the
5760 control of Guix is that it supports transactional system upgrades, and
5761 makes it possible to roll-back to a previous system instantiation,
5762 should something go wrong with the new one (@pxref{Features}). Another
5763 one is that it makes it easy to replicate the exact same configuration
5764 across different machines, or at different points in time, without
5765 having to resort to additional administration tools layered on top of
5766 the system's own tools.
5767 @c Yes, we're talking of Puppet, Chef, & co. here. ↑
5769 This section describes this mechanism. First we focus on the system
5770 administrator's viewpoint---explaining how the system is configured and
5771 instantiated. Then we show how this mechanism can be extended, for
5772 instance to support new system services.
5775 * Using the Configuration System:: Customizing your GNU system.
5776 * operating-system Reference:: Detail of operating-system declarations.
5777 * File Systems:: Configuring file system mounts.
5778 * Mapped Devices:: Block device extra processing.
5779 * User Accounts:: Specifying user accounts.
5780 * Locales:: Language and cultural convention settings.
5781 * Services:: Specifying system services.
5782 * Setuid Programs:: Programs running with root privileges.
5783 * X.509 Certificates:: Authenticating HTTPS servers.
5784 * Name Service Switch:: Configuring libc's name service switch.
5785 * Initial RAM Disk:: Linux-Libre bootstrapping.
5786 * GRUB Configuration:: Configuring the boot loader.
5787 * Invoking guix system:: Instantiating a system configuration.
5788 * Running GuixSD in a VM:: How to run GuixSD in a virtual machine.
5789 * Defining Services:: Adding new service definitions.
5792 @node Using the Configuration System
5793 @subsection Using the Configuration System
5795 The operating system is configured by providing an
5796 @code{operating-system} declaration in a file that can then be passed to
5797 the @command{guix system} command (@pxref{Invoking guix system}). A
5798 simple setup, with the default system services, the default Linux-Libre
5799 kernel, initial RAM disk, and boot loader looks like this:
5801 @findex operating-system
5803 @include os-config-bare-bones.texi
5806 This example should be self-describing. Some of the fields defined
5807 above, such as @code{host-name} and @code{bootloader}, are mandatory.
5808 Others, such as @code{packages} and @code{services}, can be omitted, in
5809 which case they get a default value.
5811 Below we discuss the effect of some of the most important fields
5812 (@pxref{operating-system Reference}, for details about all the available
5813 fields), and how to @dfn{instantiate} the operating system using
5814 @command{guix system}.
5816 @unnumberedsubsubsec Globally-Visible Packages
5818 @vindex %base-packages
5819 The @code{packages} field lists packages that will be globally visible
5820 on the system, for all user accounts---i.e., in every user's @code{PATH}
5821 environment variable---in addition to the per-user profiles
5822 (@pxref{Invoking guix package}). The @var{%base-packages} variable
5823 provides all the tools one would expect for basic user and administrator
5824 tasks---including the GNU Core Utilities, the GNU Networking Utilities,
5825 the GNU Zile lightweight text editor, @command{find}, @command{grep},
5826 etc. The example above adds tcpdump to those, taken from the @code{(gnu
5827 packages admin)} module (@pxref{Package Modules}).
5829 @findex specification->package
5830 Referring to packages by variable name, like @var{tcpdump} above, has
5831 the advantage of being unambiguous; it also allows typos and such to be
5832 diagnosed right away as ``unbound variables''. The downside is that one
5833 needs to know which module defines which package, and to augment the
5834 @code{use-package-modules} line accordingly. To avoid that, one can use
5835 the @code{specification->package} procedure of the @code{(gnu packages)}
5836 module, which returns the best package for a given name or name and
5840 (use-modules (gnu packages))
5844 (packages (append (map specification->package
5845 '("tcpdump" "htop" "gnupg-2.0"))
5849 @unnumberedsubsubsec System Services
5851 @vindex %base-services
5852 The @code{services} field lists @dfn{system services} to be made
5853 available when the system starts (@pxref{Services}).
5854 The @code{operating-system} declaration above specifies that, in
5855 addition to the basic services, we want the @command{lshd} secure shell
5856 daemon listening on port 2222 (@pxref{Networking Services,
5857 @code{lsh-service}}). Under the hood,
5858 @code{lsh-service} arranges so that @code{lshd} is started with the
5859 right command-line options, possibly with supporting configuration files
5860 generated as needed (@pxref{Defining Services}).
5862 @cindex customization, of services
5863 @findex modify-services
5864 Occasionally, instead of using the base services as is, you will want to
5865 customize them. For instance, to change the configuration of
5866 @code{guix-daemon} and Mingetty (the console log-in), you may write the
5867 following instead of @var{%base-services}:
5870 (modify-services %base-services
5871 (guix-service-type config =>
5874 (use-substitutes? #f)
5875 (extra-options '("--gc-keep-outputs"))))
5876 (mingetty-service-type config =>
5877 (mingetty-configuration
5879 (motd (plain-file "motd" "Hi there!")))))
5883 The effect here is to change the options passed to @command{guix-daemon}
5884 when it is started, as well as the ``message of the day'' that appears
5885 when logging in at the console. @xref{Service Reference,
5886 @code{modify-services}}, for more on that.
5888 The configuration for a typical ``desktop'' usage, with the X11 display
5889 server, a desktop environment, network management, power management, and
5890 more, would look like this:
5893 @include os-config-desktop.texi
5896 @xref{Desktop Services}, for the exact list of services provided by
5897 @var{%desktop-services}. @xref{X.509 Certificates}, for background
5898 information about the @code{nss-certs} package that is used here.
5900 Again, @var{%desktop-services} is just a list of service objects. If
5901 you want to remove services from there, you can do so using the
5902 procedures for list filtering (@pxref{SRFI-1 Filtering and
5903 Partitioning,,, guile, GNU Guile Reference Manual}). For instance, the
5904 following expression returns a list that contains all the services in
5905 @var{%desktop-services} minus the Avahi service:
5908 (remove (lambda (service)
5909 (eq? (service-kind service) avahi-service-type))
5913 @unnumberedsubsubsec Instantiating the System
5915 Assuming the @code{operating-system} declaration
5916 is stored in the @file{my-system-config.scm}
5917 file, the @command{guix system reconfigure my-system-config.scm} command
5918 instantiates that configuration, and makes it the default GRUB boot
5919 entry (@pxref{Invoking guix system}).
5921 The normal way to change the system's configuration is by updating this
5922 file and re-running @command{guix system reconfigure}. One should never
5923 have to touch files in @command{/etc} or to run commands that modify the
5924 system state such as @command{useradd} or @command{grub-install}. In
5925 fact, you must avoid that since that would not only void your warranty
5926 but also prevent you from rolling back to previous versions of your
5927 system, should you ever need to.
5929 @cindex roll-back, of the operating system
5930 Speaking of roll-back, each time you run @command{guix system
5931 reconfigure}, a new @dfn{generation} of the system is created---without
5932 modifying or deleting previous generations. Old system generations get
5933 an entry in the GRUB boot menu, allowing you to boot them in case
5934 something went wrong with the latest generation. Reassuring, no? The
5935 @command{guix system list-generations} command lists the system
5936 generations available on disk.
5938 @unnumberedsubsubsec The Programming Interface
5940 At the Scheme level, the bulk of an @code{operating-system} declaration
5941 is instantiated with the following monadic procedure (@pxref{The Store
5944 @deffn {Monadic Procedure} operating-system-derivation os
5945 Return a derivation that builds @var{os}, an @code{operating-system}
5946 object (@pxref{Derivations}).
5948 The output of the derivation is a single directory that refers to all
5949 the packages, configuration files, and other supporting files needed to
5950 instantiate @var{os}.
5953 This procedure is provided by the @code{(gnu system)} module. Along
5954 with @code{(gnu services)} (@pxref{Services}), this module contains the
5955 guts of GuixSD. Make sure to visit it!
5958 @node operating-system Reference
5959 @subsection @code{operating-system} Reference
5961 This section summarizes all the options available in
5962 @code{operating-system} declarations (@pxref{Using the Configuration
5965 @deftp {Data Type} operating-system
5966 This is the data type representing an operating system configuration.
5967 By that, we mean all the global system configuration, not per-user
5968 configuration (@pxref{Using the Configuration System}).
5971 @item @code{kernel} (default: @var{linux-libre})
5972 The package object of the operating system kernel to use@footnote{Currently
5973 only the Linux-libre kernel is supported. In the future, it will be
5974 possible to use the GNU@tie{}Hurd.}.
5976 @item @code{kernel-arguments} (default: @code{'()})
5977 List of strings or gexps representing additional arguments to pass on
5978 the kernel's command-line---e.g., @code{("console=ttyS0")}.
5980 @item @code{bootloader}
5981 The system bootloader configuration object. @xref{GRUB Configuration}.
5983 @item @code{initrd} (default: @code{base-initrd})
5984 A two-argument monadic procedure that returns an initial RAM disk for
5985 the Linux kernel. @xref{Initial RAM Disk}.
5987 @item @code{firmware} (default: @var{%base-firmware})
5989 List of firmware packages loadable by the operating system kernel.
5991 The default includes firmware needed for Atheros-based WiFi devices
5992 (Linux-libre module @code{ath9k}.)
5994 @item @code{host-name}
5997 @item @code{hosts-file}
5999 A file-like object (@pxref{G-Expressions, file-like objects}) for use as
6000 @file{/etc/hosts} (@pxref{Host Names,,, libc, The GNU C Library
6001 Reference Manual}). The default is a file with entries for
6002 @code{localhost} and @var{host-name}.
6004 @item @code{mapped-devices} (default: @code{'()})
6005 A list of mapped devices. @xref{Mapped Devices}.
6007 @item @code{file-systems}
6008 A list of file systems. @xref{File Systems}.
6010 @item @code{swap-devices} (default: @code{'()})
6011 @cindex swap devices
6012 A list of strings identifying devices to be used for ``swap space''
6013 (@pxref{Memory Concepts,,, libc, The GNU C Library Reference Manual}).
6014 For example, @code{'("/dev/sda3")}.
6016 @item @code{users} (default: @code{%base-user-accounts})
6017 @itemx @code{groups} (default: @var{%base-groups})
6018 List of user accounts and groups. @xref{User Accounts}.
6020 @item @code{skeletons} (default: @code{(default-skeletons)})
6021 A monadic list of pairs of target file name and files. These are the
6022 files that will be used as skeletons as new accounts are created.
6024 For instance, a valid value may look like this:
6027 (mlet %store-monad ((bashrc (text-file "bashrc" "\
6028 export PATH=$HOME/.guix-profile/bin")))
6029 (return `((".bashrc" ,bashrc))))
6032 @item @code{issue} (default: @var{%default-issue})
6033 A string denoting the contents of the @file{/etc/issue} file, which is
6034 what displayed when users log in on a text console.
6036 @item @code{packages} (default: @var{%base-packages})
6037 The set of packages installed in the global profile, which is accessible
6038 at @file{/run/current-system/profile}.
6040 The default set includes core utilities, but it is good practice to
6041 install non-core utilities in user profiles (@pxref{Invoking guix
6044 @item @code{timezone}
6045 A timezone identifying string---e.g., @code{"Europe/Paris"}.
6047 You can run the @command{tzselect} command to find out which timezone
6048 string corresponds to your region. Choosing an invalid timezone name
6049 causes @command{guix system} to fail.
6051 @item @code{locale} (default: @code{"en_US.utf8"})
6052 The name of the default locale (@pxref{Locale Names,,, libc, The GNU C
6053 Library Reference Manual}). @xref{Locales}, for more information.
6055 @item @code{locale-definitions} (default: @var{%default-locale-definitions})
6056 The list of locale definitions to be compiled and that may be used at
6057 run time. @xref{Locales}.
6059 @item @code{locale-libcs} (default: @code{(list @var{glibc})})
6060 The list of GNU@tie{}libc packages whose locale data and tools are used
6061 to build the locale definitions. @xref{Locales}, for compatibility
6062 considerations that justify this option.
6064 @item @code{name-service-switch} (default: @var{%default-nss})
6065 Configuration of libc's name service switch (NSS)---a
6066 @code{<name-service-switch>} object. @xref{Name Service Switch}, for
6069 @item @code{services} (default: @var{%base-services})
6070 A list of service objects denoting system services. @xref{Services}.
6072 @item @code{pam-services} (default: @code{(base-pam-services)})
6074 @cindex pluggable authentication modules
6075 Linux @dfn{pluggable authentication module} (PAM) services.
6076 @c FIXME: Add xref to PAM services section.
6078 @item @code{setuid-programs} (default: @var{%setuid-programs})
6079 List of string-valued G-expressions denoting setuid programs.
6080 @xref{Setuid Programs}.
6082 @item @code{sudoers-file} (default: @var{%sudoers-specification})
6083 @cindex sudoers file
6084 The contents of the @file{/etc/sudoers} file as a file-like object
6085 (@pxref{G-Expressions, @code{local-file} and @code{plain-file}}).
6087 This file specifies which users can use the @command{sudo} command, what
6088 they are allowed to do, and what privileges they may gain. The default
6089 is that only @code{root} and members of the @code{wheel} group may use
6096 @subsection File Systems
6098 The list of file systems to be mounted is specified in the
6099 @code{file-systems} field of the operating system's declaration
6100 (@pxref{Using the Configuration System}). Each file system is declared
6101 using the @code{file-system} form, like this:
6105 (mount-point "/home")
6106 (device "/dev/sda3")
6110 As usual, some of the fields are mandatory---those shown in the example
6111 above---while others can be omitted. These are described below.
6113 @deftp {Data Type} file-system
6114 Objects of this type represent file systems to be mounted. They
6115 contain the following members:
6119 This is a string specifying the type of the file system---e.g.,
6122 @item @code{mount-point}
6123 This designates the place where the file system is to be mounted.
6126 This names the ``source'' of the file system. By default it is the name
6127 of a node under @file{/dev}, but its meaning depends on the @code{title}
6128 field described below.
6130 @item @code{title} (default: @code{'device})
6131 This is a symbol that specifies how the @code{device} field is to be
6134 When it is the symbol @code{device}, then the @code{device} field is
6135 interpreted as a file name; when it is @code{label}, then @code{device}
6136 is interpreted as a partition label name; when it is @code{uuid},
6137 @code{device} is interpreted as a partition unique identifier (UUID).
6139 UUIDs may be converted from their string representation (as shown by the
6140 @command{tune2fs -l} command) using the @code{uuid} form, like this:
6144 (mount-point "/home")
6147 (device (uuid "4dab5feb-d176-45de-b287-9b0a6e4c01cb")))
6150 The @code{label} and @code{uuid} options offer a way to refer to disk
6151 partitions without having to hard-code their actual device
6152 name@footnote{Note that, while it is tempting to use
6153 @file{/dev/disk/by-uuid} and similar device names to achieve the same
6154 result, this is not recommended: These special device nodes are created
6155 by the udev daemon and may be unavailable at the time the device is
6158 However, when a file system's source is a mapped device (@pxref{Mapped
6159 Devices}), its @code{device} field @emph{must} refer to the mapped
6160 device name---e.g., @file{/dev/mapper/root-partition}---and consequently
6161 @code{title} must be set to @code{'device}. This is required so that
6162 the system knows that mounting the file system depends on having the
6163 corresponding device mapping established.
6165 @item @code{flags} (default: @code{'()})
6166 This is a list of symbols denoting mount flags. Recognized flags
6167 include @code{read-only}, @code{bind-mount}, @code{no-dev} (disallow
6168 access to special files), @code{no-suid} (ignore setuid and setgid
6169 bits), and @code{no-exec} (disallow program execution.)
6171 @item @code{options} (default: @code{#f})
6172 This is either @code{#f}, or a string denoting mount options.
6174 @item @code{mount?} (default: @code{#t})
6175 This value indicates whether to automatically mount the file system when
6176 the system is brought up. When set to @code{#f}, the file system gets
6177 an entry in @file{/etc/fstab} (read by the @command{mount} command) but
6178 is not automatically mounted.
6180 @item @code{needed-for-boot?} (default: @code{#f})
6181 This Boolean value indicates whether the file system is needed when
6182 booting. If that is true, then the file system is mounted when the
6183 initial RAM disk (initrd) is loaded. This is always the case, for
6184 instance, for the root file system.
6186 @item @code{check?} (default: @code{#t})
6187 This Boolean indicates whether the file system needs to be checked for
6188 errors before being mounted.
6190 @item @code{create-mount-point?} (default: @code{#f})
6191 When true, the mount point is created if it does not exist yet.
6193 @item @code{dependencies} (default: @code{'()})
6194 This is a list of @code{<file-system>} objects representing file systems
6195 that must be mounted before (and unmounted after) this one.
6197 As an example, consider a hierarchy of mounts: @file{/sys/fs/cgroup} is
6198 a dependency of @file{/sys/fs/cgroup/cpu} and
6199 @file{/sys/fs/cgroup/memory}.
6204 The @code{(gnu system file-systems)} exports the following useful
6207 @defvr {Scheme Variable} %base-file-systems
6208 These are essential file systems that are required on normal systems,
6209 such as @var{%pseudo-terminal-file-system} and @var{%immutable-store} (see
6210 below.) Operating system declarations should always contain at least
6214 @defvr {Scheme Variable} %pseudo-terminal-file-system
6215 This is the file system to be mounted as @file{/dev/pts}. It supports
6216 @dfn{pseudo-terminals} created @i{via} @code{openpty} and similar
6217 functions (@pxref{Pseudo-Terminals,,, libc, The GNU C Library Reference
6218 Manual}). Pseudo-terminals are used by terminal emulators such as
6222 @defvr {Scheme Variable} %shared-memory-file-system
6223 This file system is mounted as @file{/dev/shm} and is used to support
6224 memory sharing across processes (@pxref{Memory-mapped I/O,
6225 @code{shm_open},, libc, The GNU C Library Reference Manual}).
6228 @defvr {Scheme Variable} %immutable-store
6229 This file system performs a read-only ``bind mount'' of
6230 @file{/gnu/store}, making it read-only for all the users including
6231 @code{root}. This prevents against accidental modification by software
6232 running as @code{root} or by system administrators.
6234 The daemon itself is still able to write to the store: it remounts it
6235 read-write in its own ``name space.''
6238 @defvr {Scheme Variable} %binary-format-file-system
6239 The @code{binfmt_misc} file system, which allows handling of arbitrary
6240 executable file types to be delegated to user space. This requires the
6241 @code{binfmt.ko} kernel module to be loaded.
6244 @defvr {Scheme Variable} %fuse-control-file-system
6245 The @code{fusectl} file system, which allows unprivileged users to mount
6246 and unmount user-space FUSE file systems. This requires the
6247 @code{fuse.ko} kernel module to be loaded.
6250 @node Mapped Devices
6251 @subsection Mapped Devices
6253 @cindex device mapping
6254 @cindex mapped devices
6255 The Linux kernel has a notion of @dfn{device mapping}: a block device,
6256 such as a hard disk partition, can be @dfn{mapped} into another device,
6257 with additional processing over the data that flows through
6258 it@footnote{Note that the GNU@tie{}Hurd makes no difference between the
6259 concept of a ``mapped device'' and that of a file system: both boil down
6260 to @emph{translating} input/output operations made on a file to
6261 operations on its backing store. Thus, the Hurd implements mapped
6262 devices, like file systems, using the generic @dfn{translator} mechanism
6263 (@pxref{Translators,,, hurd, The GNU Hurd Reference Manual}).}. A
6264 typical example is encryption device mapping: all writes to the mapped
6265 device are encrypted, and all reads are deciphered, transparently.
6267 Mapped devices are declared using the @code{mapped-device} form:
6271 (source "/dev/sda3")
6273 (type luks-device-mapping))
6277 @cindex disk encryption
6279 This example specifies a mapping from @file{/dev/sda3} to
6280 @file{/dev/mapper/home} using LUKS---the
6281 @url{http://code.google.com/p/cryptsetup,Linux Unified Key Setup}, a
6282 standard mechanism for disk encryption. The @file{/dev/mapper/home}
6283 device can then be used as the @code{device} of a @code{file-system}
6284 declaration (@pxref{File Systems}). The @code{mapped-device} form is
6287 @deftp {Data Type} mapped-device
6288 Objects of this type represent device mappings that will be made when
6289 the system boots up.
6293 This string specifies the name of the block device to be mapped, such as
6297 This string specifies the name of the mapping to be established. For
6298 example, specifying @code{"my-partition"} will lead to the creation of
6299 the @code{"/dev/mapper/my-partition"} device.
6302 This must be a @code{mapped-device-kind} object, which specifies how
6303 @var{source} is mapped to @var{target}.
6307 @defvr {Scheme Variable} luks-device-mapping
6308 This defines LUKS block device encryption using the @command{cryptsetup}
6309 command, from the same-named package. This relies on the
6310 @code{dm-crypt} Linux kernel module.
6314 @subsection User Accounts
6316 User accounts and groups are entirely managed through the
6317 @code{operating-system} declaration. They are specified with the
6318 @code{user-account} and @code{user-group} forms:
6324 (supplementary-groups '("wheel" ;allow use of sudo, etc.
6326 "video" ;video devices such as webcams
6327 "cdrom")) ;the good ol' CD-ROM
6328 (comment "Bob's sister")
6329 (home-directory "/home/alice"))
6332 When booting or upon completion of @command{guix system reconfigure},
6333 the system ensures that only the user accounts and groups specified in
6334 the @code{operating-system} declaration exist, and with the specified
6335 properties. Thus, account or group creations or modifications made by
6336 directly invoking commands such as @command{useradd} are lost upon
6337 reconfiguration or reboot. This ensures that the system remains exactly
6340 @deftp {Data Type} user-account
6341 Objects of this type represent user accounts. The following members may
6346 The name of the user account.
6349 This is the name (a string) or identifier (a number) of the user group
6350 this account belongs to.
6352 @item @code{supplementary-groups} (default: @code{'()})
6353 Optionally, this can be defined as a list of group names that this
6356 @item @code{uid} (default: @code{#f})
6357 This is the user ID for this account (a number), or @code{#f}. In the
6358 latter case, a number is automatically chosen by the system when the
6361 @item @code{comment} (default: @code{""})
6362 A comment about the account, such as the account's owner full name.
6364 @item @code{home-directory}
6365 This is the name of the home directory for the account.
6367 @item @code{shell} (default: Bash)
6368 This is a G-expression denoting the file name of a program to be used as
6369 the shell (@pxref{G-Expressions}).
6371 @item @code{system?} (default: @code{#f})
6372 This Boolean value indicates whether the account is a ``system''
6373 account. System accounts are sometimes treated specially; for instance,
6374 graphical login managers do not list them.
6376 @anchor{user-account-password}
6377 @item @code{password} (default: @code{#f})
6378 You would normally leave this field to @code{#f}, initialize user
6379 passwords as @code{root} with the @command{passwd} command, and then let
6380 users change it with @command{passwd}. Passwords set with
6381 @command{passwd} are of course preserved across reboot and
6384 If you @emph{do} want to have a preset password for an account, then
6385 this field must contain the encrypted password, as a string.
6386 @xref{crypt,,, libc, The GNU C Library Reference Manual}, for more information
6387 on password encryption, and @ref{Encryption,,, guile, GNU Guile Reference
6388 Manual}, for information on Guile's @code{crypt} procedure.
6393 User group declarations are even simpler:
6396 (user-group (name "students"))
6399 @deftp {Data Type} user-group
6400 This type is for, well, user groups. There are just a few fields:
6406 @item @code{id} (default: @code{#f})
6407 The group identifier (a number). If @code{#f}, a new number is
6408 automatically allocated when the group is created.
6410 @item @code{system?} (default: @code{#f})
6411 This Boolean value indicates whether the group is a ``system'' group.
6412 System groups have low numerical IDs.
6414 @item @code{password} (default: @code{#f})
6415 What, user groups can have a password? Well, apparently yes. Unless
6416 @code{#f}, this field specifies the group's password.
6421 For convenience, a variable lists all the basic user groups one may
6424 @defvr {Scheme Variable} %base-groups
6425 This is the list of basic user groups that users and/or packages expect
6426 to be present on the system. This includes groups such as ``root'',
6427 ``wheel'', and ``users'', as well as groups used to control access to
6428 specific devices such as ``audio'', ``disk'', and ``cdrom''.
6431 @defvr {Scheme Variable} %base-user-accounts
6432 This is the list of basic system accounts that programs may expect to
6433 find on a GNU/Linux system, such as the ``nobody'' account.
6435 Note that the ``root'' account is not included here. It is a
6436 special-case and is automatically added whether or not it is specified.
6443 A @dfn{locale} defines cultural conventions for a particular language
6444 and region of the world (@pxref{Locales,,, libc, The GNU C Library
6445 Reference Manual}). Each locale has a name that typically has the form
6446 @code{@var{language}_@var{territory}.@var{codeset}}---e.g.,
6447 @code{fr_LU.utf8} designates the locale for the French language, with
6448 cultural conventions from Luxembourg, and using the UTF-8 encoding.
6450 @cindex locale definition
6451 Usually, you will want to specify the default locale for the machine
6452 using the @code{locale} field of the @code{operating-system} declaration
6453 (@pxref{operating-system Reference, @code{locale}}).
6455 That locale must be among the @dfn{locale definitions} that are known to
6456 the system---and these are specified in the @code{locale-definitions}
6457 slot of @code{operating-system}. The default value includes locale
6458 definitions for some widely used locales, but not for all the available
6459 locales, in order to save space.
6461 If the locale specified in the @code{locale} field is not among the
6462 definitions listed in @code{locale-definitions}, @command{guix system}
6463 raises an error. In that case, you should add the locale definition to
6464 the @code{locale-definitions} field. For instance, to add the North
6465 Frisian locale for Germany, the value of that field may be:
6468 (cons (locale-definition
6469 (name "fy_DE.utf8") (source "fy_DE"))
6470 %default-locale-definitions)
6473 Likewise, to save space, one might want @code{locale-definitions} to
6474 list only the locales that are actually used, as in:
6477 (list (locale-definition
6478 (name "ja_JP.eucjp") (source "ja_JP")
6479 (charset "EUC-JP")))
6483 The compiled locale definitions are available at
6484 @file{/run/current-system/locale/X.Y}, where @code{X.Y} is the libc
6485 version, which is the default location where the GNU@tie{}libc provided
6486 by Guix looks for locale data. This can be overridden using the
6487 @code{LOCPATH} environment variable (@pxref{locales-and-locpath,
6488 @code{LOCPATH} and locale packages}).
6490 The @code{locale-definition} form is provided by the @code{(gnu system
6491 locale)} module. Details are given below.
6493 @deftp {Data Type} locale-definition
6494 This is the data type of a locale definition.
6499 The name of the locale. @xref{Locale Names,,, libc, The GNU C Library
6500 Reference Manual}, for more information on locale names.
6503 The name of the source for that locale. This is typically the
6504 @code{@var{language}_@var{territory}} part of the locale name.
6506 @item @code{charset} (default: @code{"UTF-8"})
6507 The ``character set'' or ``code set'' for that locale,
6508 @uref{http://www.iana.org/assignments/character-sets, as defined by
6514 @defvr {Scheme Variable} %default-locale-definitions
6515 An arbitrary list of commonly used UTF-8 locales, used as the default
6516 value of the @code{locale-definitions} field of @code{operating-system}
6520 @cindex normalized codeset in locale names
6521 These locale definitions use the @dfn{normalized codeset} for the part
6522 that follows the dot in the name (@pxref{Using gettextized software,
6523 normalized codeset,, libc, The GNU C Library Reference Manual}). So for
6524 instance it has @code{uk_UA.utf8} but @emph{not}, say,
6528 @subsubsection Locale Data Compatibility Considerations
6530 @cindex incompatibility, of locale data
6531 @code{operating-system} declarations provide a @code{locale-libcs} field
6532 to specify the GNU@tie{}libc packages that are used to compile locale
6533 declarations (@pxref{operating-system Reference}). ``Why would I
6534 care?'', you may ask. Well, it turns out that the binary format of
6535 locale data is occasionally incompatible from one libc version to
6538 @c See <https://sourceware.org/ml/libc-alpha/2015-09/msg00575.html>
6539 @c and <https://lists.gnu.org/archive/html/guix-devel/2015-08/msg00737.html>.
6540 For instance, a program linked against libc version 2.21 is unable to
6541 read locale data produced with libc 2.22; worse, that program
6542 @emph{aborts} instead of simply ignoring the incompatible locale
6543 data@footnote{Versions 2.23 and later of GNU@tie{}libc will simply skip
6544 the incompatible locale data, which is already an improvement.}.
6545 Similarly, a program linked against libc 2.22 can read most, but not
6546 all, the locale data from libc 2.21 (specifically, @code{LC_COLLATE}
6547 data is incompatible); thus calls to @code{setlocale} may fail, but
6548 programs will not abort.
6550 The ``problem'' in GuixSD is that users have a lot of freedom: They can
6551 choose whether and when to upgrade software in their profiles, and might
6552 be using a libc version different from the one the system administrator
6553 used to build the system-wide locale data.
6555 Fortunately, unprivileged users can also install their own locale data
6556 and define @var{GUIX_LOCPATH} accordingly (@pxref{locales-and-locpath,
6557 @code{GUIX_LOCPATH} and locale packages}).
6559 Still, it is best if the system-wide locale data at
6560 @file{/run/current-system/locale} is built for all the libc versions
6561 actually in use on the system, so that all the programs can access
6562 it---this is especially crucial on a multi-user system. To do that, the
6563 administrator can specify several libc packages in the
6564 @code{locale-libcs} field of @code{operating-system}:
6567 (use-package-modules base)
6571 (locale-libcs (list glibc-2.21 (canonical-package glibc))))
6574 This example would lead to a system containing locale definitions for
6575 both libc 2.21 and the current version of libc in
6576 @file{/run/current-system/locale}.
6580 @subsection Services
6582 @cindex system services
6583 An important part of preparing an @code{operating-system} declaration is
6584 listing @dfn{system services} and their configuration (@pxref{Using the
6585 Configuration System}). System services are typically daemons launched
6586 when the system boots, or other actions needed at that time---e.g.,
6587 configuring network access.
6589 Services are managed by the GNU@tie{}Shepherd (@pxref{Introduction,,,
6590 shepherd, The GNU Shepherd Manual}). On a running system, the
6591 @command{herd} command allows you to list the available services, show
6592 their status, start and stop them, or do other specific operations
6593 (@pxref{Jump Start,,, shepherd, The GNU Shepherd Manual}). For example:
6599 The above command, run as @code{root}, lists the currently defined
6600 services. The @command{herd doc} command shows a synopsis of the given
6605 Run libc's name service cache daemon (nscd).
6608 The @command{start}, @command{stop}, and @command{restart} sub-commands
6609 have the effect you would expect. For instance, the commands below stop
6610 the nscd service and restart the Xorg display server:
6614 Service nscd has been stopped.
6615 # herd restart xorg-server
6616 Service xorg-server has been stopped.
6617 Service xorg-server has been started.
6620 The following sections document the available services, starting with
6621 the core services, that may be used in an @code{operating-system}
6625 * Base Services:: Essential system services.
6626 * Networking Services:: Network setup, SSH daemon, etc.
6627 * X Window:: Graphical display.
6628 * Desktop Services:: D-Bus and desktop services.
6629 * Database Services:: SQL databases.
6630 * Mail Services:: IMAP, POP3, SMTP, and all that.
6631 * Web Services:: Web servers.
6632 * Various Services:: Other services.
6636 @subsubsection Base Services
6638 The @code{(gnu services base)} module provides definitions for the basic
6639 services that one expects from the system. The services exported by
6640 this module are listed below.
6642 @defvr {Scheme Variable} %base-services
6643 This variable contains a list of basic services (@pxref{Service Types
6644 and Services}, for more information on service objects) one would
6645 expect from the system: a login service (mingetty) on each tty, syslogd,
6646 libc's name service cache daemon (nscd), the udev device manager, and
6649 This is the default value of the @code{services} field of
6650 @code{operating-system} declarations. Usually, when customizing a
6651 system, you will want to append services to @var{%base-services}, like
6655 (cons* (avahi-service) (lsh-service) %base-services)
6659 @deffn {Scheme Procedure} host-name-service @var{name}
6660 Return a service that sets the host name to @var{name}.
6663 @deffn {Scheme Procedure} mingetty-service @var{config}
6664 Return a service to run mingetty according to @var{config}, a
6665 @code{<mingetty-configuration>} object, which specifies the tty to run, among
6669 @deftp {Data Type} mingetty-configuration
6670 This is the data type representing the configuration of Mingetty, which
6671 implements console log-in.
6676 The name of the console this Mingetty runs on---e.g., @code{"tty1"}.
6679 A file-like object containing the ``message of the day''.
6681 @item @code{auto-login} (default: @code{#f})
6682 When true, this field must be a string denoting the user name under
6683 which the system automatically logs in. When it is @code{#f}, a
6684 user name and password must be entered to log in.
6686 @item @code{login-program} (default: @code{#f})
6687 This must be either @code{#f}, in which case the default log-in program
6688 is used (@command{login} from the Shadow tool suite), or a gexp denoting
6689 the name of the log-in program.
6691 @item @code{login-pause?} (default: @code{#f})
6692 When set to @code{#t} in conjunction with @var{auto-login}, the user
6693 will have to press a key before the log-in shell is launched.
6695 @item @code{mingetty} (default: @var{mingetty})
6696 The Mingetty package to use.
6701 @cindex name service cache daemon
6703 @deffn {Scheme Procedure} nscd-service [@var{config}] [#:glibc glibc] @
6704 [#:name-services '()]
6705 Return a service that runs libc's name service cache daemon (nscd) with the
6706 given @var{config}---an @code{<nscd-configuration>} object. @xref{Name
6707 Service Switch}, for an example.
6710 @defvr {Scheme Variable} %nscd-default-configuration
6711 This is the default @code{<nscd-configuration>} value (see below) used
6712 by @code{nscd-service}. This uses the caches defined by
6713 @var{%nscd-default-caches}; see below.
6716 @deftp {Data Type} nscd-configuration
6717 This is the type representing the name service cache daemon (nscd)
6722 @item @code{name-services} (default: @code{'()})
6723 List of packages denoting @dfn{name services} that must be visible to
6724 the nscd---e.g., @code{(list @var{nss-mdns})}.
6726 @item @code{glibc} (default: @var{glibc})
6727 Package object denoting the GNU C Library providing the @command{nscd}
6730 @item @code{log-file} (default: @code{"/var/log/nscd.log"})
6731 Name of nscd's log file. This is where debugging output goes when
6732 @code{debug-level} is strictly positive.
6734 @item @code{debug-level} (default: @code{0})
6735 Integer denoting the debugging levels. Higher numbers mean more
6736 debugging output is logged.
6738 @item @code{caches} (default: @var{%nscd-default-caches})
6739 List of @code{<nscd-cache>} objects denoting things to be cached; see
6745 @deftp {Data Type} nscd-cache
6746 Data type representing a cache database of nscd and its parameters.
6750 @item @code{database}
6751 This is a symbol representing the name of the database to be cached.
6752 Valid values are @code{passwd}, @code{group}, @code{hosts}, and
6753 @code{services}, which designate the corresponding NSS database
6754 (@pxref{NSS Basics,,, libc, The GNU C Library Reference Manual}).
6756 @item @code{positive-time-to-live}
6757 @itemx @code{negative-time-to-live} (default: @code{20})
6758 A number representing the number of seconds during which a positive or
6759 negative lookup result remains in cache.
6761 @item @code{check-files?} (default: @code{#t})
6762 Whether to check for updates of the files corresponding to
6765 For instance, when @var{database} is @code{hosts}, setting this flag
6766 instructs nscd to check for updates in @file{/etc/hosts} and to take
6769 @item @code{persistent?} (default: @code{#t})
6770 Whether the cache should be stored persistently on disk.
6772 @item @code{shared?} (default: @code{#t})
6773 Whether the cache should be shared among users.
6775 @item @code{max-database-size} (default: 32@tie{}MiB)
6776 Maximum size in bytes of the database cache.
6778 @c XXX: 'suggested-size' and 'auto-propagate?' seem to be expert
6779 @c settings, so leave them out.
6784 @defvr {Scheme Variable} %nscd-default-caches
6785 List of @code{<nscd-cache>} objects used by default by
6786 @code{nscd-configuration} (see above.)
6788 It enables persistent and aggressive caching of service and host name
6789 lookups. The latter provides better host name lookup performance,
6790 resilience in the face of unreliable name servers, and also better
6791 privacy---often the result of host name lookups is in local cache, so
6792 external name servers do not even need to be queried.
6796 @deffn {Scheme Procedure} syslog-service [#:config-file #f]
6797 Return a service that runs @code{syslogd}. If configuration file name
6798 @var{config-file} is not specified, use some reasonable default
6802 @anchor{guix-configuration-type}
6803 @deftp {Data Type} guix-configuration
6804 This data type represents the configuration of the Guix build daemon.
6805 @xref{Invoking guix-daemon}, for more information.
6808 @item @code{guix} (default: @var{guix})
6809 The Guix package to use.
6811 @item @code{build-group} (default: @code{"guixbuild"})
6812 Name of the group for build user accounts.
6814 @item @code{build-accounts} (default: @code{10})
6815 Number of build user accounts to create.
6817 @item @code{authorize-key?} (default: @code{#t})
6818 Whether to authorize the substitute key for @code{hydra.gnu.org}
6819 (@pxref{Substitutes}).
6821 @item @code{use-substitutes?} (default: @code{#t})
6822 Whether to use substitutes.
6824 @item @code{substitute-urls} (default: @var{%default-substitute-urls})
6825 The list of URLs where to look for substitutes by default.
6827 @item @code{extra-options} (default: @code{'()})
6828 List of extra command-line options for @command{guix-daemon}.
6830 @item @code{lsof} (default: @var{lsof})
6831 @itemx @code{lsh} (default: @var{lsh})
6832 The lsof and lsh packages to use.
6837 @deffn {Scheme Procedure} guix-service @var{config}
6838 Return a service that runs the Guix build daemon according to
6842 @deffn {Scheme Procedure} udev-service [#:udev udev]
6843 Run @var{udev}, which populates the @file{/dev} directory dynamically.
6846 @deffn {Scheme Procedure} console-keymap-service @var{file}
6847 Return a service to load console keymap from @var{file} using
6848 @command{loadkeys} command.
6851 @deffn {Scheme Procedure} gpm-service-type [#:gpm @var{gpm}] @
6853 Run @var{gpm}, the general-purpose mouse daemon, with the given
6854 command-line @var{options}. GPM allows users to use the mouse in the console,
6855 notably to select, copy, and paste text. The default value of @var{options}
6856 uses the @code{ps2} protocol, which works for both USB and PS/2 mice.
6858 This service is not part of @var{%base-services}.
6861 @anchor{guix-publish-service}
6862 @deffn {Scheme Procedure} guix-publish-service [#:guix @var{guix}] @
6863 [#:port 80] [#:host "localhost"]
6864 Return a service that runs @command{guix publish} listening on @var{host}
6865 and @var{port} (@pxref{Invoking guix publish}).
6867 This assumes that @file{/etc/guix} already contains a signing key pair as
6868 created by @command{guix archive --generate-key} (@pxref{Invoking guix
6869 archive}). If that is not the case, the service will fail to start.
6873 @node Networking Services
6874 @subsubsection Networking Services
6876 The @code{(gnu services networking)} module provides services to configure
6877 the network interface.
6879 @cindex DHCP, networking service
6880 @deffn {Scheme Procedure} dhcp-client-service [#:dhcp @var{isc-dhcp}]
6881 Return a service that runs @var{dhcp}, a Dynamic Host Configuration
6882 Protocol (DHCP) client, on all the non-loopback network interfaces.
6885 @deffn {Scheme Procedure} static-networking-service @var{interface} @var{ip} @
6886 [#:gateway #f] [#:name-services @code{'()}]
6887 Return a service that starts @var{interface} with address @var{ip}. If
6888 @var{gateway} is true, it must be a string specifying the default network
6893 @cindex network management
6894 @deffn {Scheme Procedure} wicd-service [#:wicd @var{wicd}]
6895 Return a service that runs @url{https://launchpad.net/wicd,Wicd}, a network
6896 management daemon that aims to simplify wired and wireless networking.
6898 This service adds the @var{wicd} package to the global profile, providing
6899 several commands to interact with the daemon and configure networking:
6900 @command{wicd-client}, a graphical user interface, and the @command{wicd-cli}
6901 and @command{wicd-curses} user interfaces.
6904 @cindex NetworkManager
6905 @deffn {Scheme Procedure} network-manager-service @
6906 [#:network-manager @var{network-manager}]
6907 Return a service that runs NetworkManager, a network connection manager
6908 that attempting to keep active network connectivity when available.
6911 @deffn {Scheme Procedure} ntp-service [#:ntp @var{ntp}] @
6912 [#:name-service @var{%ntp-servers}]
6913 Return a service that runs the daemon from @var{ntp}, the
6914 @uref{http://www.ntp.org, Network Time Protocol package}. The daemon will
6915 keep the system clock synchronized with that of @var{servers}.
6918 @defvr {Scheme Variable} %ntp-servers
6919 List of host names used as the default NTP servers.
6922 @deffn {Scheme Procedure} tor-service [@var{config-file}] [#:tor @var{tor}]
6923 Return a service to run the @uref{https://torproject.org, Tor} anonymous
6926 The daemon runs as the @code{tor} unprivileged user. It is passed
6927 @var{config-file}, a file-like object, with an additional @code{User tor} line
6928 and lines for hidden services added via @code{tor-hidden-service}. Run
6929 @command{man tor} for information about the configuration file.
6932 @cindex hidden service
6933 @deffn {Scheme Procedure} tor-hidden-service @var{name} @var{mapping}
6934 Define a new Tor @dfn{hidden service} called @var{name} and implementing
6935 @var{mapping}. @var{mapping} is a list of port/host tuples, such as:
6938 '((22 "127.0.0.1:22")
6939 (80 "127.0.0.1:8080"))
6942 In this example, port 22 of the hidden service is mapped to local port 22, and
6943 port 80 is mapped to local port 8080.
6945 This creates a @file{/var/lib/tor/hidden-services/@var{name}} directory, where
6946 the @file{hostname} file contains the @code{.onion} host name for the hidden
6949 See @uref{https://www.torproject.org/docs/tor-hidden-service.html.en, the Tor
6950 project's documentation} for more information.
6953 @deffn {Scheme Procedure} bitlbee-service [#:bitlbee bitlbee] @
6954 [#:interface "127.0.0.1"] [#:port 6667] @
6955 [#:extra-settings ""]
6956 Return a service that runs @url{http://bitlbee.org,BitlBee}, a daemon that
6957 acts as a gateway between IRC and chat networks.
6959 The daemon will listen to the interface corresponding to the IP address
6960 specified in @var{interface}, on @var{port}. @code{127.0.0.1} means that only
6961 local clients can connect, whereas @code{0.0.0.0} means that connections can
6962 come from any networking interface.
6964 In addition, @var{extra-settings} specifies a string to append to the
6968 Furthermore, @code{(gnu services ssh)} provides the following service.
6970 @deffn {Scheme Procedure} lsh-service [#:host-key "/etc/lsh/host-key"] @
6971 [#:daemonic? #t] [#:interfaces '()] [#:port-number 22] @
6972 [#:allow-empty-passwords? #f] [#:root-login? #f] @
6973 [#:syslog-output? #t] [#:x11-forwarding? #t] @
6974 [#:tcp/ip-forwarding? #t] [#:password-authentication? #t] @
6975 [#:public-key-authentication? #t] [#:initialize? #t]
6976 Run the @command{lshd} program from @var{lsh} to listen on port @var{port-number}.
6977 @var{host-key} must designate a file containing the host key, and readable
6980 When @var{daemonic?} is true, @command{lshd} will detach from the
6981 controlling terminal and log its output to syslogd, unless one sets
6982 @var{syslog-output?} to false. Obviously, it also makes lsh-service
6983 depend on existence of syslogd service. When @var{pid-file?} is true,
6984 @command{lshd} writes its PID to the file called @var{pid-file}.
6986 When @var{initialize?} is true, automatically create the seed and host key
6987 upon service activation if they do not exist yet. This may take long and
6988 require interaction.
6990 When @var{initialize?} is false, it is up to the user to initialize the
6991 randomness generator (@pxref{lsh-make-seed,,, lsh, LSH Manual}), and to create
6992 a key pair with the private key stored in file @var{host-key} (@pxref{lshd
6993 basics,,, lsh, LSH Manual}).
6995 When @var{interfaces} is empty, lshd listens for connections on all the
6996 network interfaces; otherwise, @var{interfaces} must be a list of host names
6999 @var{allow-empty-passwords?} specifies whether to accept log-ins with empty
7000 passwords, and @var{root-login?} specifies whether to accept log-ins as
7003 The other options should be self-descriptive.
7006 @defvr {Scheme Variable} %facebook-host-aliases
7007 This variable contains a string for use in @file{/etc/hosts}
7008 (@pxref{Host Names,,, libc, The GNU C Library Reference Manual}). Each
7009 line contains a entry that maps a known server name of the Facebook
7010 on-line service---e.g., @code{www.facebook.com}---to the local
7011 host---@code{127.0.0.1} or its IPv6 equivalent, @code{::1}.
7013 This variable is typically used in the @code{hosts-file} field of an
7014 @code{operating-system} declaration (@pxref{operating-system Reference,
7015 @file{/etc/hosts}}):
7018 (use-modules (gnu) (guix))
7021 (host-name "mymachine")
7024 ;; Create a /etc/hosts file with aliases for "localhost"
7025 ;; and "mymachine", as well as for Facebook servers.
7027 (string-append (local-host-aliases host-name)
7028 %facebook-host-aliases))))
7031 This mechanism can prevent programs running locally, such as Web
7032 browsers, from accessing Facebook.
7035 The @code{(gnu services avahi)} provides the following definition.
7037 @deffn {Scheme Procedure} avahi-service [#:avahi @var{avahi}] @
7038 [#:host-name #f] [#:publish? #t] [#:ipv4? #t] @
7039 [#:ipv6? #t] [#:wide-area? #f] @
7040 [#:domains-to-browse '()]
7041 Return a service that runs @command{avahi-daemon}, a system-wide
7042 mDNS/DNS-SD responder that allows for service discovery and
7043 "zero-configuration" host name lookups (see @uref{http://avahi.org/}), and
7044 extends the name service cache daemon (nscd) so that it can resolve
7045 @code{.local} host names using
7046 @uref{http://0pointer.de/lennart/projects/nss-mdns/, nss-mdns}. Additionally,
7047 add the @var{avahi} package to the system profile so that commands such as
7048 @command{avahi-browse} are directly usable.
7050 If @var{host-name} is different from @code{#f}, use that as the host name to
7051 publish for this machine; otherwise, use the machine's actual host name.
7053 When @var{publish?} is true, publishing of host names and services is allowed;
7054 in particular, avahi-daemon will publish the machine's host name and IP
7055 address via mDNS on the local network.
7057 When @var{wide-area?} is true, DNS-SD over unicast DNS is enabled.
7059 Boolean values @var{ipv4?} and @var{ipv6?} determine whether to use IPv4/IPv6
7065 @subsubsection X Window
7067 Support for the X Window graphical display system---specifically
7068 Xorg---is provided by the @code{(gnu services xorg)} module. Note that
7069 there is no @code{xorg-service} procedure. Instead, the X server is
7070 started by the @dfn{login manager}, currently SLiM.
7072 @deffn {Scheme Procedure} slim-service [#:allow-empty-passwords? #f] @
7073 [#:auto-login? #f] [#:default-user ""] [#:startx] @
7074 [#:theme @var{%default-slim-theme}] @
7075 [#:theme-name @var{%default-slim-theme-name}]
7076 Return a service that spawns the SLiM graphical login manager, which in
7077 turn starts the X display server with @var{startx}, a command as returned by
7078 @code{xorg-start-command}.
7082 SLiM automatically looks for session types described by the @file{.desktop}
7083 files in @file{/run/current-system/profile/share/xsessions} and allows users
7084 to choose a session from the log-in screen using @kbd{F1}. Packages such as
7085 @var{xfce}, @var{sawfish}, and @var{ratpoison} provide @file{.desktop} files;
7086 adding them to the system-wide set of packages automatically makes them
7087 available at the log-in screen.
7089 In addition, @file{~/.xsession} files are honored. When available,
7090 @file{~/.xsession} must be an executable that starts a window manager
7091 and/or other X clients.
7093 When @var{allow-empty-passwords?} is true, allow logins with an empty
7094 password. When @var{auto-login?} is true, log in automatically as
7097 If @var{theme} is @code{#f}, the use the default log-in theme; otherwise
7098 @var{theme} must be a gexp denoting the name of a directory containing the
7099 theme to use. In that case, @var{theme-name} specifies the name of the
7103 @defvr {Scheme Variable} %default-theme
7104 @defvrx {Scheme Variable} %default-theme-name
7105 The G-Expression denoting the default SLiM theme and its name.
7108 @deffn {Scheme Procedure} xorg-start-command [#:guile] @
7109 [#:configuration-file #f] [#:xorg-server @var{xorg-server}]
7110 Return a derivation that builds a @var{guile} script to start the X server
7111 from @var{xorg-server}. @var{configuration-file} is the server configuration
7112 file or a derivation that builds it; when omitted, the result of
7113 @code{xorg-configuration-file} is used.
7115 Usually the X server is started by a login manager.
7118 @deffn {Scheme Procedure} xorg-configuration-file @
7119 [#:drivers '()] [#:resolutions '()] [#:extra-config '()]
7120 Return a configuration file for the Xorg server containing search paths for
7121 all the common drivers.
7123 @var{drivers} must be either the empty list, in which case Xorg chooses a
7124 graphics driver automatically, or a list of driver names that will be tried in
7125 this order---e.g., @code{(\"modesetting\" \"vesa\")}.
7127 Likewise, when @var{resolutions} is the empty list, Xorg chooses an
7128 appropriate screen resolution; otherwise, it must be a list of
7129 resolutions---e.g., @code{((1024 768) (640 480))}.
7131 Last, @var{extra-config} is a list of strings or objects appended to the
7132 @code{text-file*} argument list. It is used to pass extra text to be added
7133 verbatim to the configuration file.
7136 @deffn {Scheme Procedure} screen-locker-service @var{package} [@var{name}]
7137 Add @var{package}, a package for a screen-locker or screen-saver whose
7138 command is @var{program}, to the set of setuid programs and add a PAM entry
7139 for it. For example:
7142 (screen-locker-service xlockmore "xlock")
7145 makes the good ol' XlockMore usable.
7149 @node Desktop Services
7150 @subsubsection Desktop Services
7152 The @code{(gnu services desktop)} module provides services that are
7153 usually useful in the context of a ``desktop'' setup---that is, on a
7154 machine running a graphical display server, possibly with graphical user
7157 To simplify things, the module defines a variable containing the set of
7158 services that users typically expect on a machine with a graphical
7159 environment and networking:
7161 @defvr {Scheme Variable} %desktop-services
7162 This is a list of services that builds upon @var{%base-services} and
7163 adds or adjust services for a typical ``desktop'' setup.
7165 In particular, it adds a graphical login manager (@pxref{X Window,
7166 @code{slim-service}}), screen lockers,
7167 a network management tool (@pxref{Networking
7168 Services, @code{wicd-service}}), energy and color management services,
7169 the @code{elogind} login and seat manager, the Polkit privilege service,
7170 the GeoClue location service, an NTP client (@pxref{Networking
7171 Services}), the Avahi daemon, and has the name service switch service
7172 configured to be able to use @code{nss-mdns} (@pxref{Name Service
7176 The @var{%desktop-services} variable can be used as the @code{services}
7177 field of an @code{operating-system} declaration (@pxref{operating-system
7178 Reference, @code{services}}).
7180 The actual service definitions provided by @code{(gnu services dbus)}
7181 and @code{(gnu services desktop)} are described below.
7183 @deffn {Scheme Procedure} dbus-service [#:dbus @var{dbus}] [#:services '()]
7184 Return a service that runs the ``system bus'', using @var{dbus}, with
7185 support for @var{services}.
7187 @uref{http://dbus.freedesktop.org/, D-Bus} is an inter-process communication
7188 facility. Its system bus is used to allow system services to communicate
7189 and be notified of system-wide events.
7191 @var{services} must be a list of packages that provide an
7192 @file{etc/dbus-1/system.d} directory containing additional D-Bus configuration
7193 and policy files. For example, to allow avahi-daemon to use the system bus,
7194 @var{services} must be equal to @code{(list avahi)}.
7197 @deffn {Scheme Procedure} elogind-service [#:config @var{config}]
7198 Return a service that runs the @code{elogind} login and
7199 seat management daemon. @uref{https://github.com/andywingo/elogind,
7200 Elogind} exposes a D-Bus interface that can be used to know which users
7201 are logged in, know what kind of sessions they have open, suspend the
7202 system, inhibit system suspend, reboot the system, and other tasks.
7204 Elogind handles most system-level power events for a computer, for
7205 example suspending the system when a lid is closed, or shutting it down
7206 when the power button is pressed.
7208 The @var{config} keyword argument specifies the configuration for
7209 elogind, and should be the result of a @code{(elogind-configuration
7210 (@var{parameter} @var{value})...)} invocation. Available parameters and
7211 their default values are:
7214 @item kill-user-processes?
7216 @item kill-only-users
7218 @item kill-exclude-users
7220 @item inhibit-delay-max-seconds
7222 @item handle-power-key
7224 @item handle-suspend-key
7226 @item handle-hibernate-key
7228 @item handle-lid-switch
7230 @item handle-lid-switch-docked
7232 @item power-key-ignore-inhibited?
7234 @item suspend-key-ignore-inhibited?
7236 @item hibernate-key-ignore-inhibited?
7238 @item lid-switch-ignore-inhibited?
7240 @item holdoff-timeout-seconds
7244 @item idle-action-seconds
7246 @item runtime-directory-size-percent
7248 @item runtime-directory-size
7253 @code{("mem" "standby" "freeze")}
7256 @item hibernate-state
7258 @item hibernate-mode
7259 @code{("platform" "shutdown")}
7260 @item hybrid-sleep-state
7262 @item hybrid-sleep-mode
7263 @code{("suspend" "platform" "shutdown")}
7267 @deffn {Scheme Procedure} polkit-service @
7268 [#:polkit @var{polkit}]
7269 Return a service that runs the
7270 @uref{http://www.freedesktop.org/wiki/Software/polkit/, Polkit privilege
7271 management service}, which allows system administrators to grant access to
7272 privileged operations in a structured way. By querying the Polkit service, a
7273 privileged system component can know when it should grant additional
7274 capabilities to ordinary users. For example, an ordinary user can be granted
7275 the capability to suspend the system if the user is logged in locally.
7278 @deffn {Scheme Procedure} upower-service [#:upower @var{upower}] @
7279 [#:watts-up-pro? #f] @
7280 [#:poll-batteries? #t] @
7281 [#:ignore-lid? #f] @
7282 [#:use-percentage-for-policy? #f] @
7283 [#:percentage-low 10] @
7284 [#:percentage-critical 3] @
7285 [#:percentage-action 2] @
7287 [#:time-critical 300] @
7288 [#:time-action 120] @
7289 [#:critical-power-action 'hybrid-sleep]
7290 Return a service that runs @uref{http://upower.freedesktop.org/,
7291 @command{upowerd}}, a system-wide monitor for power consumption and battery
7292 levels, with the given configuration settings. It implements the
7293 @code{org.freedesktop.UPower} D-Bus interface, and is notably used by
7297 @deffn {Scheme Procedure} udisks-service [#:udisks @var{udisks}]
7298 Return a service for @uref{http://udisks.freedesktop.org/docs/latest/,
7299 UDisks}, a @dfn{disk management} daemon that provides user interfaces with
7300 notifications and ways to mount/unmount disks. Programs that talk to UDisks
7301 include the @command{udisksctl} command, part of UDisks, and GNOME Disks.
7304 @deffn {Scheme Procedure} colord-service [#:colord @var{colord}]
7305 Return a service that runs @command{colord}, a system service with a D-Bus
7306 interface to manage the color profiles of input and output devices such as
7307 screens and scanners. It is notably used by the GNOME Color Manager graphical
7308 tool. See @uref{http://www.freedesktop.org/software/colord/, the colord web
7309 site} for more information.
7312 @deffn {Scheme Procedure} geoclue-application name [#:allowed? #t] [#:system? #f] [#:users '()]
7313 Return an configuration allowing an application to access GeoClue
7314 location data. @var{name} is the Desktop ID of the application, without
7315 the @code{.desktop} part. If @var{allowed?} is true, the application
7316 will have access to location information by default. The boolean
7317 @var{system?} value indicates that an application is a system component
7318 or not. Finally @var{users} is a list of UIDs of all users for which
7319 this application is allowed location info access. An empty users list
7320 means that all users are allowed.
7323 @defvr {Scheme Variable} %standard-geoclue-applications
7324 The standard list of well-known GeoClue application configurations,
7325 granting authority to GNOME's date-and-time utility to ask for the
7326 current location in order to set the time zone, and allowing the Firefox
7327 (IceCat) and Epiphany web browsers to request location information.
7328 Firefox and Epiphany both query the user before allowing a web page to
7329 know the user's location.
7332 @deffn {Scheme Procedure} geoclue-service [#:colord @var{colord}] @
7334 [#:wifi-geolocation-url "https://location.services.mozilla.com/v1/geolocate?key=geoclue"] @
7336 [#:wifi-submission-url "https://location.services.mozilla.com/v1/submit?key=geoclue"] @
7337 [#:submission-nick "geoclue"] @
7338 [#:applications %standard-geoclue-applications]
7339 Return a service that runs the GeoClue location service. This service
7340 provides a D-Bus interface to allow applications to request access to a
7341 user's physical location, and optionally to add information to online
7342 location databases. See
7343 @uref{https://wiki.freedesktop.org/www/Software/GeoClue/, the GeoClue
7344 web site} for more information.
7347 @node Database Services
7348 @subsubsection Database Services
7350 The @code{(gnu services databases)} module provides the following service.
7352 @deffn {Scheme Procedure} postgresql-service [#:postgresql postgresql] @
7353 [#:config-file] [#:data-directory ``/var/lib/postgresql/data'']
7354 Return a service that runs @var{postgresql}, the PostgreSQL database
7357 The PostgreSQL daemon loads its runtime configuration from
7358 @var{config-file} and stores the database cluster in
7359 @var{data-directory}.
7363 @subsubsection Mail Services
7365 The @code{(gnu services mail)} module provides Guix service definitions
7366 for mail services. Currently the only implemented service is Dovecot,
7367 an IMAP, POP3, and LMTP server.
7369 Guix does not yet have a mail transfer agent (MTA), although for some
7370 lightweight purposes the @code{esmtp} relay-only MTA may suffice. Help
7371 is needed to properly integrate a full MTA, such as Postfix. Patches
7374 To add an IMAP/POP3 server to a GuixSD system, add a
7375 @code{dovecot-service} to the operating system definition:
7377 @deffn {Scheme Procedure} dovecot-service [#:config (dovecot-configuration)]
7378 Return a service that runs the Dovecot IMAP/POP3/LMTP mail server.
7381 By default, Dovecot doesn't need much configuration; the default
7382 configuration object created by @code{(dovecot-configuration)} will
7383 suffice if your mail is delivered to @code{~/Maildir}. A self-signed
7384 certificate will be generated for TLS-protected connections, though
7385 Dovecot will also listen on cleartext ports by default. There are a
7386 number of options though which mail administrators might need to change,
7387 and as is the case with other services, Guix allows the system
7388 administrator to specify these parameters via a uniform Scheme interface.
7390 For example, to specify that mail is located at @code{maildir~/.mail},
7391 one would instantiate the Dovecot service like this:
7394 (dovecot-service #:config
7395 (dovecot-configuration
7396 (mail-location "maildir:~/.mail")))
7399 The available configuration parameters follow. Each parameter
7400 definition is preceded by its type; for example, @samp{string-list foo}
7401 indicates that the @code{foo} parameter should be specified as a list of
7402 strings. There is also a way to specify the configuration as a string,
7403 if you have an old @code{dovecot.conf} file that you want to port over
7404 from some other system; see the end for more details.
7406 @c The following documentation was initially generated by
7407 @c (generate-documentation) in (gnu services mail). Manually maintained
7408 @c documentation is better, so we shouldn't hesitate to edit below as
7409 @c needed. However if the change you want to make to this documentation
7410 @c can be done in an automated way, it's probably easier to change
7411 @c (generate-documentation) than to make it below and have to deal with
7412 @c the churn as dovecot updates.
7414 Available @code{dovecot-configuration} fields are:
7416 @deftypevr {@code{dovecot-configuration} parameter} package dovecot
7417 The dovecot package.
7420 @deftypevr {@code{dovecot-configuration} parameter} comma-separated-string-list listen
7421 A list of IPs or hosts where to listen in for connections. @samp{*}
7422 listens in all IPv4 interfaces, @samp{::} listens in all IPv6
7423 interfaces. If you want to specify non-default ports or anything more
7424 complex, customize the address and port fields of the
7425 @samp{inet-listener} of the specific services you are interested in.
7428 @deftypevr {@code{dovecot-configuration} parameter} protocol-configuration-list protocols
7429 List of protocols we want to serve. Available protocols include
7430 @samp{imap}, @samp{pop3}, and @samp{lmtp}.
7432 Available @code{protocol-configuration} fields are:
7434 @deftypevr {@code{protocol-configuration} parameter} string name
7435 The name of the protocol.
7438 @deftypevr {@code{protocol-configuration} parameter} string auth-socket-path
7439 UNIX socket path to master authentication server to find users.
7440 This is used by imap (for shared users) and lda.
7441 Defaults to @samp{"/var/run/dovecot/auth-userdb"}.
7444 @deftypevr {@code{protocol-configuration} parameter} space-separated-string-list mail-plugins
7445 Space separated list of plugins to load.
7448 @deftypevr {@code{protocol-configuration} parameter} non-negative-integer mail-max-userip-connections
7449 Maximum number of IMAP connections allowed for a user from each IP
7450 address. NOTE: The username is compared case-sensitively.
7451 Defaults to @samp{10}.
7456 @deftypevr {@code{dovecot-configuration} parameter} service-configuration-list services
7457 List of services to enable. Available services include @samp{imap},
7458 @samp{imap-login}, @samp{pop3}, @samp{pop3-login}, @samp{auth}, and
7461 Available @code{service-configuration} fields are:
7463 @deftypevr {@code{service-configuration} parameter} string kind
7464 The service kind. Valid values include @code{director},
7465 @code{imap-login}, @code{pop3-login}, @code{lmtp}, @code{imap},
7466 @code{pop3}, @code{auth}, @code{auth-worker}, @code{dict},
7467 @code{tcpwrap}, @code{quota-warning}, or anything else.
7470 @deftypevr {@code{service-configuration} parameter} listener-configuration-list listeners
7471 Listeners for the service. A listener is either an
7472 @code{unix-listener-configuration}, a @code{fifo-listener-configuration}, or
7473 an @code{inet-listener-configuration}.
7474 Defaults to @samp{()}.
7476 Available @code{unix-listener-configuration} fields are:
7478 @deftypevr {@code{unix-listener-configuration} parameter} file-name path
7479 The file name on which to listen.
7482 @deftypevr {@code{unix-listener-configuration} parameter} string mode
7483 The access mode for the socket.
7484 Defaults to @samp{"0600"}.
7487 @deftypevr {@code{unix-listener-configuration} parameter} string user
7488 The user to own the socket.
7489 Defaults to @samp{""}.
7492 @deftypevr {@code{unix-listener-configuration} parameter} string group
7493 The group to own the socket.
7494 Defaults to @samp{""}.
7498 Available @code{fifo-listener-configuration} fields are:
7500 @deftypevr {@code{fifo-listener-configuration} parameter} file-name path
7501 The file name on which to listen.
7504 @deftypevr {@code{fifo-listener-configuration} parameter} string mode
7505 The access mode for the socket.
7506 Defaults to @samp{"0600"}.
7509 @deftypevr {@code{fifo-listener-configuration} parameter} string user
7510 The user to own the socket.
7511 Defaults to @samp{""}.
7514 @deftypevr {@code{fifo-listener-configuration} parameter} string group
7515 The group to own the socket.
7516 Defaults to @samp{""}.
7520 Available @code{inet-listener-configuration} fields are:
7522 @deftypevr {@code{inet-listener-configuration} parameter} string protocol
7523 The protocol to listen for.
7526 @deftypevr {@code{inet-listener-configuration} parameter} string address
7527 The address on which to listen, or empty for all addresses.
7528 Defaults to @samp{""}.
7531 @deftypevr {@code{inet-listener-configuration} parameter} non-negative-integer port
7532 The port on which to listen.
7535 @deftypevr {@code{inet-listener-configuration} parameter} boolean ssl?
7536 Whether to use SSL for this service; @samp{yes}, @samp{no}, or
7538 Defaults to @samp{#t}.
7543 @deftypevr {@code{service-configuration} parameter} non-negative-integer service-count
7544 Number of connections to handle before starting a new process.
7545 Typically the only useful values are 0 (unlimited) or 1. 1 is more
7546 secure, but 0 is faster. <doc/wiki/LoginProcess.txt>.
7547 Defaults to @samp{1}.
7550 @deftypevr {@code{service-configuration} parameter} non-negative-integer process-min-avail
7551 Number of processes to always keep waiting for more connections.
7552 Defaults to @samp{0}.
7555 @deftypevr {@code{service-configuration} parameter} non-negative-integer vsz-limit
7556 If you set @samp{service-count 0}, you probably need to grow
7558 Defaults to @samp{256000000}.
7563 @deftypevr {@code{dovecot-configuration} parameter} dict-configuration dict
7564 Dict configuration, as created by the @code{dict-configuration}
7567 Available @code{dict-configuration} fields are:
7569 @deftypevr {@code{dict-configuration} parameter} free-form-fields entries
7570 A list of key-value pairs that this dict should hold.
7571 Defaults to @samp{()}.
7576 @deftypevr {@code{dovecot-configuration} parameter} passdb-configuration-list passdbs
7577 List of passdb configurations, each one created by the
7578 @code{passdb-configuration} constructor.
7580 Available @code{passdb-configuration} fields are:
7582 @deftypevr {@code{passdb-configuration} parameter} string driver
7583 The driver that the passdb should use. Valid values include
7584 @samp{pam}, @samp{passwd}, @samp{shadow}, @samp{bsdauth}, and
7586 Defaults to @samp{"pam"}.
7589 @deftypevr {@code{passdb-configuration} parameter} free-form-args args
7590 A list of key-value args to the passdb driver.
7591 Defaults to @samp{()}.
7596 @deftypevr {@code{dovecot-configuration} parameter} userdb-configuration-list userdbs
7597 List of userdb configurations, each one created by the
7598 @code{userdb-configuration} constructor.
7600 Available @code{userdb-configuration} fields are:
7602 @deftypevr {@code{userdb-configuration} parameter} string driver
7603 The driver that the userdb should use. Valid values include
7604 @samp{passwd} and @samp{static}.
7605 Defaults to @samp{"passwd"}.
7608 @deftypevr {@code{userdb-configuration} parameter} free-form-args args
7609 A list of key-value args to the userdb driver.
7610 Defaults to @samp{()}.
7613 @deftypevr {@code{userdb-configuration} parameter} free-form-args override-fields
7614 Override fields from passwd.
7615 Defaults to @samp{()}.
7620 @deftypevr {@code{dovecot-configuration} parameter} plugin-configuration plugin-configuration
7621 Plug-in configuration, created by the @code{plugin-configuration}
7625 @deftypevr {@code{dovecot-configuration} parameter} list-of-namespace-configuration namespaces
7626 List of namespaces. Each item in the list is created by the
7627 @code{namespace-configuration} constructor.
7629 Available @code{namespace-configuration} fields are:
7631 @deftypevr {@code{namespace-configuration} parameter} string name
7632 Name for this namespace.
7635 @deftypevr {@code{namespace-configuration} parameter} string type
7636 Namespace type: @samp{private}, @samp{shared} or @samp{public}.
7637 Defaults to @samp{"private"}.
7640 @deftypevr {@code{namespace-configuration} parameter} string separator
7641 Hierarchy separator to use. You should use the same separator for
7642 all namespaces or some clients get confused. @samp{/} is usually a good
7643 one. The default however depends on the underlying mail storage
7645 Defaults to @samp{""}.
7648 @deftypevr {@code{namespace-configuration} parameter} string prefix
7649 Prefix required to access this namespace. This needs to be
7650 different for all namespaces. For example @samp{Public/}.
7651 Defaults to @samp{""}.
7654 @deftypevr {@code{namespace-configuration} parameter} string location
7655 Physical location of the mailbox. This is in same format as
7656 mail_location, which is also the default for it.
7657 Defaults to @samp{""}.
7660 @deftypevr {@code{namespace-configuration} parameter} boolean inbox?
7661 There can be only one INBOX, and this setting defines which
7663 Defaults to @samp{#f}.
7666 @deftypevr {@code{namespace-configuration} parameter} boolean hidden?
7667 If namespace is hidden, it's not advertised to clients via NAMESPACE
7668 extension. You'll most likely also want to set @samp{list? #f}. This is mostly
7669 useful when converting from another server with different namespaces
7670 which you want to deprecate but still keep working. For example you can
7671 create hidden namespaces with prefixes @samp{~/mail/}, @samp{~%u/mail/}
7673 Defaults to @samp{#f}.
7676 @deftypevr {@code{namespace-configuration} parameter} boolean list?
7677 Show the mailboxes under this namespace with LIST command. This
7678 makes the namespace visible for clients that don't support NAMESPACE
7679 extension. The special @code{children} value lists child mailboxes, but
7680 hides the namespace prefix.
7681 Defaults to @samp{#t}.
7684 @deftypevr {@code{namespace-configuration} parameter} boolean subscriptions?
7685 Namespace handles its own subscriptions. If set to @code{#f}, the
7686 parent namespace handles them. The empty prefix should always have this
7688 Defaults to @samp{#t}.
7691 @deftypevr {@code{namespace-configuration} parameter} mailbox-configuration-list mailboxes
7692 List of predefined mailboxes in this namespace.
7693 Defaults to @samp{()}.
7695 Available @code{mailbox-configuration} fields are:
7697 @deftypevr {@code{mailbox-configuration} parameter} string name
7698 Name for this mailbox.
7701 @deftypevr {@code{mailbox-configuration} parameter} string auto
7702 @samp{create} will automatically create this mailbox.
7703 @samp{subscribe} will both create and subscribe to the mailbox.
7704 Defaults to @samp{"no"}.
7707 @deftypevr {@code{mailbox-configuration} parameter} space-separated-string-list special-use
7708 List of IMAP @code{SPECIAL-USE} attributes as specified by RFC 6154.
7709 Valid values are @code{\All}, @code{\Archive}, @code{\Drafts},
7710 @code{\Flagged}, @code{\Junk}, @code{\Sent}, and @code{\Trash}.
7711 Defaults to @samp{()}.
7718 @deftypevr {@code{dovecot-configuration} parameter} file-name base-dir
7719 Base directory where to store runtime data.
7720 Defaults to @samp{"/var/run/dovecot/"}.
7723 @deftypevr {@code{dovecot-configuration} parameter} string login-greeting
7724 Greeting message for clients.
7725 Defaults to @samp{"Dovecot ready."}.
7728 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-trusted-networks
7729 List of trusted network ranges. Connections from these IPs are
7730 allowed to override their IP addresses and ports (for logging and for
7731 authentication checks). @samp{disable-plaintext-auth} is also ignored
7732 for these networks. Typically you'd specify your IMAP proxy servers
7734 Defaults to @samp{()}.
7737 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-access-sockets
7738 List of login access check sockets (e.g. tcpwrap).
7739 Defaults to @samp{()}.
7742 @deftypevr {@code{dovecot-configuration} parameter} boolean verbose-proctitle?
7743 Show more verbose process titles (in ps). Currently shows user name
7744 and IP address. Useful for seeing who are actually using the IMAP
7745 processes (e.g. shared mailboxes or if same uid is used for multiple
7747 Defaults to @samp{#f}.
7750 @deftypevr {@code{dovecot-configuration} parameter} boolean shutdown-clients?
7751 Should all processes be killed when Dovecot master process shuts down.
7752 Setting this to @code{#f} means that Dovecot can be upgraded without
7753 forcing existing client connections to close (although that could also
7754 be a problem if the upgrade is e.g. because of a security fix).
7755 Defaults to @samp{#t}.
7758 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer doveadm-worker-count
7759 If non-zero, run mail commands via this many connections to doveadm
7760 server, instead of running them directly in the same process.
7761 Defaults to @samp{0}.
7764 @deftypevr {@code{dovecot-configuration} parameter} string doveadm-socket-path
7765 UNIX socket or host:port used for connecting to doveadm server.
7766 Defaults to @samp{"doveadm-server"}.
7769 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list import-environment
7770 List of environment variables that are preserved on Dovecot startup
7771 and passed down to all of its child processes. You can also give
7772 key=value pairs to always set specific settings.
7775 @deftypevr {@code{dovecot-configuration} parameter} boolean disable-plaintext-auth?
7776 Disable LOGIN command and all other plaintext authentications unless
7777 SSL/TLS is used (LOGINDISABLED capability). Note that if the remote IP
7778 matches the local IP (i.e. you're connecting from the same computer),
7779 the connection is considered secure and plaintext authentication is
7780 allowed. See also ssl=required setting.
7781 Defaults to @samp{#t}.
7784 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer auth-cache-size
7785 Authentication cache size (e.g. @samp{#e10e6}). 0 means it's disabled.
7786 Note that bsdauth, PAM and vpopmail require @samp{cache-key} to be set
7787 for caching to be used.
7788 Defaults to @samp{0}.
7791 @deftypevr {@code{dovecot-configuration} parameter} string auth-cache-ttl
7792 Time to live for cached data. After TTL expires the cached record
7793 is no longer used, *except* if the main database lookup returns internal
7794 failure. We also try to handle password changes automatically: If
7795 user's previous authentication was successful, but this one wasn't, the
7796 cache isn't used. For now this works only with plaintext
7798 Defaults to @samp{"1 hour"}.
7801 @deftypevr {@code{dovecot-configuration} parameter} string auth-cache-negative-ttl
7802 TTL for negative hits (user not found, password mismatch).
7803 0 disables caching them completely.
7804 Defaults to @samp{"1 hour"}.
7807 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list auth-realms
7808 List of realms for SASL authentication mechanisms that need them.
7809 You can leave it empty if you don't want to support multiple realms.
7810 Many clients simply use the first one listed here, so keep the default
7812 Defaults to @samp{()}.
7815 @deftypevr {@code{dovecot-configuration} parameter} string auth-default-realm
7816 Default realm/domain to use if none was specified. This is used for
7817 both SASL realms and appending @@domain to username in plaintext
7819 Defaults to @samp{""}.
7822 @deftypevr {@code{dovecot-configuration} parameter} string auth-username-chars
7823 List of allowed characters in username. If the user-given username
7824 contains a character not listed in here, the login automatically fails.
7825 This is just an extra check to make sure user can't exploit any
7826 potential quote escaping vulnerabilities with SQL/LDAP databases. If
7827 you want to allow all characters, set this value to empty.
7828 Defaults to @samp{"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890.-_@@"}.
7831 @deftypevr {@code{dovecot-configuration} parameter} string auth-username-translation
7832 Username character translations before it's looked up from
7833 databases. The value contains series of from -> to characters. For
7834 example @samp{#@@/@@} means that @samp{#} and @samp{/} characters are
7835 translated to @samp{@@}.
7836 Defaults to @samp{""}.
7839 @deftypevr {@code{dovecot-configuration} parameter} string auth-username-format
7840 Username formatting before it's looked up from databases. You can
7841 use the standard variables here, e.g. %Lu would lowercase the username,
7842 %n would drop away the domain if it was given, or @samp{%n-AT-%d} would
7843 change the @samp{@@} into @samp{-AT-}. This translation is done after
7844 @samp{auth-username-translation} changes.
7845 Defaults to @samp{"%Lu"}.
7848 @deftypevr {@code{dovecot-configuration} parameter} string auth-master-user-separator
7849 If you want to allow master users to log in by specifying the master
7850 username within the normal username string (i.e. not using SASL
7851 mechanism's support for it), you can specify the separator character
7852 here. The format is then <username><separator><master username>.
7853 UW-IMAP uses @samp{*} as the separator, so that could be a good
7855 Defaults to @samp{""}.
7858 @deftypevr {@code{dovecot-configuration} parameter} string auth-anonymous-username
7859 Username to use for users logging in with ANONYMOUS SASL
7861 Defaults to @samp{"anonymous"}.
7864 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer auth-worker-max-count
7865 Maximum number of dovecot-auth worker processes. They're used to
7866 execute blocking passdb and userdb queries (e.g. MySQL and PAM).
7867 They're automatically created and destroyed as needed.
7868 Defaults to @samp{30}.
7871 @deftypevr {@code{dovecot-configuration} parameter} string auth-gssapi-hostname
7872 Host name to use in GSSAPI principal names. The default is to use
7873 the name returned by gethostname(). Use @samp{$ALL} (with quotes) to
7874 allow all keytab entries.
7875 Defaults to @samp{""}.
7878 @deftypevr {@code{dovecot-configuration} parameter} string auth-krb5-keytab
7879 Kerberos keytab to use for the GSSAPI mechanism. Will use the
7880 system default (usually /etc/krb5.keytab) if not specified. You may
7881 need to change the auth service to run as root to be able to read this
7883 Defaults to @samp{""}.
7886 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-use-winbind?
7887 Do NTLM and GSS-SPNEGO authentication using Samba's winbind daemon
7888 and @samp{ntlm-auth} helper.
7889 <doc/wiki/Authentication/Mechanisms/Winbind.txt>.
7890 Defaults to @samp{#f}.
7893 @deftypevr {@code{dovecot-configuration} parameter} file-name auth-winbind-helper-path
7894 Path for Samba's @samp{ntlm-auth} helper binary.
7895 Defaults to @samp{"/usr/bin/ntlm_auth"}.
7898 @deftypevr {@code{dovecot-configuration} parameter} string auth-failure-delay
7899 Time to delay before replying to failed authentications.
7900 Defaults to @samp{"2 secs"}.
7903 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-ssl-require-client-cert?
7904 Require a valid SSL client certificate or the authentication
7906 Defaults to @samp{#f}.
7909 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-ssl-username-from-cert?
7910 Take the username from client's SSL certificate, using
7911 @code{X509_NAME_get_text_by_NID()} which returns the subject's DN's
7913 Defaults to @samp{#f}.
7916 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list auth-mechanisms
7917 List of wanted authentication mechanisms. Supported mechanisms are:
7918 @samp{plain}, @samp{login}, @samp{digest-md5}, @samp{cram-md5},
7919 @samp{ntlm}, @samp{rpa}, @samp{apop}, @samp{anonymous}, @samp{gssapi},
7920 @samp{otp}, @samp{skey}, and @samp{gss-spnego}. NOTE: See also
7921 @samp{disable-plaintext-auth} setting.
7924 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list director-servers
7925 List of IPs or hostnames to all director servers, including ourself.
7926 Ports can be specified as ip:port. The default port is the same as what
7927 director service's @samp{inet-listener} is using.
7928 Defaults to @samp{()}.
7931 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list director-mail-servers
7932 List of IPs or hostnames to all backend mail servers. Ranges are
7933 allowed too, like 10.0.0.10-10.0.0.30.
7934 Defaults to @samp{()}.
7937 @deftypevr {@code{dovecot-configuration} parameter} string director-user-expire
7938 How long to redirect users to a specific server after it no longer
7939 has any connections.
7940 Defaults to @samp{"15 min"}.
7943 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer director-doveadm-port
7944 TCP/IP port that accepts doveadm connections (instead of director
7945 connections) If you enable this, you'll also need to add
7946 @samp{inet-listener} for the port.
7947 Defaults to @samp{0}.
7950 @deftypevr {@code{dovecot-configuration} parameter} string director-username-hash
7951 How the username is translated before being hashed. Useful values
7952 include %Ln if user can log in with or without @@domain, %Ld if mailboxes
7953 are shared within domain.
7954 Defaults to @samp{"%Lu"}.
7957 @deftypevr {@code{dovecot-configuration} parameter} string log-path
7958 Log file to use for error messages. @samp{syslog} logs to syslog,
7959 @samp{/dev/stderr} logs to stderr.
7960 Defaults to @samp{"syslog"}.
7963 @deftypevr {@code{dovecot-configuration} parameter} string info-log-path
7964 Log file to use for informational messages. Defaults to
7966 Defaults to @samp{""}.
7969 @deftypevr {@code{dovecot-configuration} parameter} string debug-log-path
7970 Log file to use for debug messages. Defaults to
7971 @samp{info-log-path}.
7972 Defaults to @samp{""}.
7975 @deftypevr {@code{dovecot-configuration} parameter} string syslog-facility
7976 Syslog facility to use if you're logging to syslog. Usually if you
7977 don't want to use @samp{mail}, you'll use local0..local7. Also other
7978 standard facilities are supported.
7979 Defaults to @samp{"mail"}.
7982 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-verbose?
7983 Log unsuccessful authentication attempts and the reasons why they
7985 Defaults to @samp{#f}.
7988 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-verbose-passwords?
7989 In case of password mismatches, log the attempted password. Valid
7990 values are no, plain and sha1. sha1 can be useful for detecting brute
7991 force password attempts vs. user simply trying the same password over
7992 and over again. You can also truncate the value to n chars by appending
7994 Defaults to @samp{#f}.
7997 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-debug?
7998 Even more verbose logging for debugging purposes. Shows for example
8000 Defaults to @samp{#f}.
8003 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-debug-passwords?
8004 In case of password mismatches, log the passwords and used scheme so
8005 the problem can be debugged. Enabling this also enables
8007 Defaults to @samp{#f}.
8010 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-debug?
8011 Enable mail process debugging. This can help you figure out why
8012 Dovecot isn't finding your mails.
8013 Defaults to @samp{#f}.
8016 @deftypevr {@code{dovecot-configuration} parameter} boolean verbose-ssl?
8017 Show protocol level SSL errors.
8018 Defaults to @samp{#f}.
8021 @deftypevr {@code{dovecot-configuration} parameter} string log-timestamp
8022 Prefix for each line written to log file. % codes are in
8024 Defaults to @samp{"\"%b %d %H:%M:%S \""}.
8027 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-log-format-elements
8028 List of elements we want to log. The elements which have a
8029 non-empty variable value are joined together to form a comma-separated
8033 @deftypevr {@code{dovecot-configuration} parameter} string login-log-format
8034 Login log format. %s contains @samp{login-log-format-elements}
8035 string, %$ contains the data we want to log.
8036 Defaults to @samp{"%$: %s"}.
8039 @deftypevr {@code{dovecot-configuration} parameter} string mail-log-prefix
8040 Log prefix for mail processes. See doc/wiki/Variables.txt for list
8041 of possible variables you can use.
8042 Defaults to @samp{"\"%s(%u): \""}.
8045 @deftypevr {@code{dovecot-configuration} parameter} string deliver-log-format
8046 Format to use for logging mail deliveries. You can use variables:
8049 Delivery status message (e.g. @samp{saved to INBOX})
8061 Defaults to @samp{"msgid=%m: %$"}.
8064 @deftypevr {@code{dovecot-configuration} parameter} string mail-location
8065 Location for users' mailboxes. The default is empty, which means
8066 that Dovecot tries to find the mailboxes automatically. This won't work
8067 if the user doesn't yet have any mail, so you should explicitly tell
8068 Dovecot the full location.
8070 If you're using mbox, giving a path to the INBOX
8071 file (e.g. /var/mail/%u) isn't enough. You'll also need to tell Dovecot
8072 where the other mailboxes are kept. This is called the "root mail
8073 directory", and it must be the first path given in the
8074 @samp{mail-location} setting.
8076 There are a few special variables you can use, eg.:
8082 user part in user@@domain, same as %u if there's no domain
8084 domain part in user@@domain, empty if there's no domain
8089 See doc/wiki/Variables.txt for full list. Some examples:
8091 @item maildir:~/Maildir
8092 @item mbox:~/mail:INBOX=/var/mail/%u
8093 @item mbox:/var/mail/%d/%1n/%n:INDEX=/var/indexes/%d/%1n/%
8095 Defaults to @samp{""}.
8098 @deftypevr {@code{dovecot-configuration} parameter} string mail-uid
8099 System user and group used to access mails. If you use multiple,
8100 userdb can override these by returning uid or gid fields. You can use
8101 either numbers or names. <doc/wiki/UserIds.txt>.
8102 Defaults to @samp{""}.
8105 @deftypevr {@code{dovecot-configuration} parameter} string mail-gid
8107 Defaults to @samp{""}.
8110 @deftypevr {@code{dovecot-configuration} parameter} string mail-privileged-group
8111 Group to enable temporarily for privileged operations. Currently
8112 this is used only with INBOX when either its initial creation or
8113 dotlocking fails. Typically this is set to "mail" to give access to
8115 Defaults to @samp{""}.
8118 @deftypevr {@code{dovecot-configuration} parameter} string mail-access-groups
8119 Grant access to these supplementary groups for mail processes.
8120 Typically these are used to set up access to shared mailboxes. Note
8121 that it may be dangerous to set these if users can create
8122 symlinks (e.g. if "mail" group is set here, ln -s /var/mail ~/mail/var
8123 could allow a user to delete others' mailboxes, or ln -s
8124 /secret/shared/box ~/mail/mybox would allow reading it).
8125 Defaults to @samp{""}.
8128 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-full-filesystem-access?
8129 Allow full filesystem access to clients. There's no access checks
8130 other than what the operating system does for the active UID/GID. It
8131 works with both maildir and mboxes, allowing you to prefix mailboxes
8132 names with e.g. /path/ or ~user/.
8133 Defaults to @samp{#f}.
8136 @deftypevr {@code{dovecot-configuration} parameter} boolean mmap-disable?
8137 Don't use mmap() at all. This is required if you store indexes to
8138 shared filesystems (NFS or clustered filesystem).
8139 Defaults to @samp{#f}.
8142 @deftypevr {@code{dovecot-configuration} parameter} boolean dotlock-use-excl?
8143 Rely on @samp{O_EXCL} to work when creating dotlock files. NFS
8144 supports @samp{O_EXCL} since version 3, so this should be safe to use
8145 nowadays by default.
8146 Defaults to @samp{#t}.
8149 @deftypevr {@code{dovecot-configuration} parameter} string mail-fsync
8150 When to use fsync() or fdatasync() calls:
8153 Whenever necessary to avoid losing important data
8155 Useful with e.g. NFS when write()s are delayed
8157 Never use it (best performance, but crashes can lose data).
8159 Defaults to @samp{"optimized"}.
8162 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-nfs-storage?
8163 Mail storage exists in NFS. Set this to yes to make Dovecot flush
8164 NFS caches whenever needed. If you're using only a single mail server
8166 Defaults to @samp{#f}.
8169 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-nfs-index?
8170 Mail index files also exist in NFS. Setting this to yes requires
8171 @samp{mmap-disable? #t} and @samp{fsync-disable? #f}.
8172 Defaults to @samp{#f}.
8175 @deftypevr {@code{dovecot-configuration} parameter} string lock-method
8176 Locking method for index files. Alternatives are fcntl, flock and
8177 dotlock. Dotlocking uses some tricks which may create more disk I/O
8178 than other locking methods. NFS users: flock doesn't work, remember to
8179 change @samp{mmap-disable}.
8180 Defaults to @samp{"fcntl"}.
8183 @deftypevr {@code{dovecot-configuration} parameter} file-name mail-temp-dir
8184 Directory in which LDA/LMTP temporarily stores incoming mails >128
8186 Defaults to @samp{"/tmp"}.
8189 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer first-valid-uid
8190 Valid UID range for users. This is mostly to make sure that users can't
8191 log in as daemons or other system users. Note that denying root logins is
8192 hardcoded to dovecot binary and can't be done even if @samp{first-valid-uid}
8194 Defaults to @samp{500}.
8197 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer last-valid-uid
8199 Defaults to @samp{0}.
8202 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer first-valid-gid
8203 Valid GID range for users. Users having non-valid GID as primary group ID
8204 aren't allowed to log in. If user belongs to supplementary groups with
8205 non-valid GIDs, those groups are not set.
8206 Defaults to @samp{1}.
8209 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer last-valid-gid
8211 Defaults to @samp{0}.
8214 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-max-keyword-length
8215 Maximum allowed length for mail keyword name. It's only forced when
8216 trying to create new keywords.
8217 Defaults to @samp{50}.
8220 @deftypevr {@code{dovecot-configuration} parameter} colon-separated-file-name-list valid-chroot-dirs
8221 List of directories under which chrooting is allowed for mail
8222 processes (i.e. /var/mail will allow chrooting to /var/mail/foo/bar
8223 too). This setting doesn't affect @samp{login-chroot}
8224 @samp{mail-chroot} or auth chroot settings. If this setting is empty,
8225 "/./" in home dirs are ignored. WARNING: Never add directories here
8226 which local users can modify, that may lead to root exploit. Usually
8227 this should be done only if you don't allow shell access for users.
8228 <doc/wiki/Chrooting.txt>.
8229 Defaults to @samp{()}.
8232 @deftypevr {@code{dovecot-configuration} parameter} string mail-chroot
8233 Default chroot directory for mail processes. This can be overridden
8234 for specific users in user database by giving /./ in user's home
8235 directory (e.g. /home/./user chroots into /home). Note that usually
8236 there is no real need to do chrooting, Dovecot doesn't allow users to
8237 access files outside their mail directory anyway. If your home
8238 directories are prefixed with the chroot directory, append "/." to
8239 @samp{mail-chroot}. <doc/wiki/Chrooting.txt>.
8240 Defaults to @samp{""}.
8243 @deftypevr {@code{dovecot-configuration} parameter} file-name auth-socket-path
8244 UNIX socket path to master authentication server to find users.
8245 This is used by imap (for shared users) and lda.
8246 Defaults to @samp{"/var/run/dovecot/auth-userdb"}.
8249 @deftypevr {@code{dovecot-configuration} parameter} file-name mail-plugin-dir
8250 Directory where to look up mail plugins.
8251 Defaults to @samp{"/usr/lib/dovecot"}.
8254 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mail-plugins
8255 List of plugins to load for all services. Plugins specific to IMAP,
8256 LDA, etc. are added to this list in their own .conf files.
8257 Defaults to @samp{()}.
8260 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-cache-min-mail-count
8261 The minimum number of mails in a mailbox before updates are done to
8262 cache file. This allows optimizing Dovecot's behavior to do less disk
8263 writes at the cost of more disk reads.
8264 Defaults to @samp{0}.
8267 @deftypevr {@code{dovecot-configuration} parameter} string mailbox-idle-check-interval
8268 When IDLE command is running, mailbox is checked once in a while to
8269 see if there are any new mails or other changes. This setting defines
8270 the minimum time to wait between those checks. Dovecot can also use
8271 dnotify, inotify and kqueue to find out immediately when changes
8273 Defaults to @samp{"30 secs"}.
8276 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-save-crlf?
8277 Save mails with CR+LF instead of plain LF. This makes sending those
8278 mails take less CPU, especially with sendfile() syscall with Linux and
8279 FreeBSD. But it also creates a bit more disk I/O which may just make it
8280 slower. Also note that if other software reads the mboxes/maildirs,
8281 they may handle the extra CRs wrong and cause problems.
8282 Defaults to @samp{#f}.
8285 @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-stat-dirs?
8286 By default LIST command returns all entries in maildir beginning
8287 with a dot. Enabling this option makes Dovecot return only entries
8288 which are directories. This is done by stat()ing each entry, so it
8289 causes more disk I/O.
8290 (For systems setting struct @samp{dirent->d_type} this check is free
8291 and it's done always regardless of this setting).
8292 Defaults to @samp{#f}.
8295 @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-copy-with-hardlinks?
8296 When copying a message, do it with hard links whenever possible.
8297 This makes the performance much better, and it's unlikely to have any
8299 Defaults to @samp{#t}.
8302 @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-very-dirty-syncs?
8303 Assume Dovecot is the only MUA accessing Maildir: Scan cur/
8304 directory only when its mtime changes unexpectedly or when we can't find
8306 Defaults to @samp{#f}.
8309 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mbox-read-locks
8310 Which locking methods to use for locking mbox. There are four
8315 Create <mailbox>.lock file. This is the oldest and most NFS-safe
8316 solution. If you want to use /var/mail/ like directory, the users will
8317 need write access to that directory.
8319 Same as dotlock, but if it fails because of permissions or because there
8320 isn't enough disk space, just skip it.
8322 Use this if possible. Works with NFS too if lockd is used.
8324 May not exist in all systems. Doesn't work with NFS.
8326 May not exist in all systems. Doesn't work with NFS.
8329 You can use multiple locking methods; if you do the order they're declared
8330 in is important to avoid deadlocks if other MTAs/MUAs are using multiple
8331 locking methods as well. Some operating systems don't allow using some of
8332 them simultaneously.
8335 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mbox-write-locks
8339 @deftypevr {@code{dovecot-configuration} parameter} string mbox-lock-timeout
8340 Maximum time to wait for lock (all of them) before aborting.
8341 Defaults to @samp{"5 mins"}.
8344 @deftypevr {@code{dovecot-configuration} parameter} string mbox-dotlock-change-timeout
8345 If dotlock exists but the mailbox isn't modified in any way,
8346 override the lock file after this much time.
8347 Defaults to @samp{"2 mins"}.
8350 @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-dirty-syncs?
8351 When mbox changes unexpectedly we have to fully read it to find out
8352 what changed. If the mbox is large this can take a long time. Since
8353 the change is usually just a newly appended mail, it'd be faster to
8354 simply read the new mails. If this setting is enabled, Dovecot does
8355 this but still safely fallbacks to re-reading the whole mbox file
8356 whenever something in mbox isn't how it's expected to be. The only real
8357 downside to this setting is that if some other MUA changes message
8358 flags, Dovecot doesn't notice it immediately. Note that a full sync is
8359 done with SELECT, EXAMINE, EXPUNGE and CHECK commands.
8360 Defaults to @samp{#t}.
8363 @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-very-dirty-syncs?
8364 Like @samp{mbox-dirty-syncs}, but don't do full syncs even with SELECT,
8365 EXAMINE, EXPUNGE or CHECK commands. If this is set,
8366 @samp{mbox-dirty-syncs} is ignored.
8367 Defaults to @samp{#f}.
8370 @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-lazy-writes?
8371 Delay writing mbox headers until doing a full write sync (EXPUNGE
8372 and CHECK commands and when closing the mailbox). This is especially
8373 useful for POP3 where clients often delete all mails. The downside is
8374 that our changes aren't immediately visible to other MUAs.
8375 Defaults to @samp{#t}.
8378 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mbox-min-index-size
8379 If mbox size is smaller than this (e.g. 100k), don't write index
8380 files. If an index file already exists it's still read, just not
8382 Defaults to @samp{0}.
8385 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mdbox-rotate-size
8386 Maximum dbox file size until it's rotated.
8387 Defaults to @samp{2000000}.
8390 @deftypevr {@code{dovecot-configuration} parameter} string mdbox-rotate-interval
8391 Maximum dbox file age until it's rotated. Typically in days. Day
8392 begins from midnight, so 1d = today, 2d = yesterday, etc. 0 = check
8394 Defaults to @samp{"1d"}.
8397 @deftypevr {@code{dovecot-configuration} parameter} boolean mdbox-preallocate-space?
8398 When creating new mdbox files, immediately preallocate their size to
8399 @samp{mdbox-rotate-size}. This setting currently works only in Linux
8400 with some filesystems (ext4, xfs).
8401 Defaults to @samp{#f}.
8404 @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-dir
8405 sdbox and mdbox support saving mail attachments to external files,
8406 which also allows single instance storage for them. Other backends
8407 don't support this for now.
8409 WARNING: This feature hasn't been tested much yet. Use at your own risk.
8411 Directory root where to store mail attachments. Disabled, if empty.
8412 Defaults to @samp{""}.
8415 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-attachment-min-size
8416 Attachments smaller than this aren't saved externally. It's also
8417 possible to write a plugin to disable saving specific attachments
8419 Defaults to @samp{128000}.
8422 @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-fs
8423 Filesystem backend to use for saving attachments:
8426 No SiS done by Dovecot (but this might help FS's own deduplication)
8428 SiS with immediate byte-by-byte comparison during saving
8429 @item sis-queue posix
8430 SiS with delayed comparison and deduplication.
8432 Defaults to @samp{"sis posix"}.
8435 @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-hash
8436 Hash format to use in attachment filenames. You can add any text and
8437 variables: @code{%@{md4@}}, @code{%@{md5@}}, @code{%@{sha1@}},
8438 @code{%@{sha256@}}, @code{%@{sha512@}}, @code{%@{size@}}. Variables can be
8439 truncated, e.g. @code{%@{sha256:80@}} returns only first 80 bits.
8440 Defaults to @samp{"%@{sha1@}"}.
8443 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-process-limit
8445 Defaults to @samp{100}.
8448 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-client-limit
8450 Defaults to @samp{1000}.
8453 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-vsz-limit
8454 Default VSZ (virtual memory size) limit for service processes.
8455 This is mainly intended to catch and kill processes that leak memory
8456 before they eat up everything.
8457 Defaults to @samp{256000000}.
8460 @deftypevr {@code{dovecot-configuration} parameter} string default-login-user
8461 Login user is internally used by login processes. This is the most
8462 untrusted user in Dovecot system. It shouldn't have access to anything
8464 Defaults to @samp{"dovenull"}.
8467 @deftypevr {@code{dovecot-configuration} parameter} string default-internal-user
8468 Internal user is used by unprivileged processes. It should be
8469 separate from login user, so that login processes can't disturb other
8471 Defaults to @samp{"dovecot"}.
8474 @deftypevr {@code{dovecot-configuration} parameter} string ssl?
8475 SSL/TLS support: yes, no, required. <doc/wiki/SSL.txt>.
8476 Defaults to @samp{"required"}.
8479 @deftypevr {@code{dovecot-configuration} parameter} string ssl-cert
8480 PEM encoded X.509 SSL/TLS certificate (public key).
8481 Defaults to @samp{"</etc/dovecot/default.pem"}.
8484 @deftypevr {@code{dovecot-configuration} parameter} string ssl-key
8485 PEM encoded SSL/TLS private key. The key is opened before
8486 dropping root privileges, so keep the key file unreadable by anyone but
8488 Defaults to @samp{"</etc/dovecot/private/default.pem"}.
8491 @deftypevr {@code{dovecot-configuration} parameter} string ssl-key-password
8492 If key file is password protected, give the password here.
8493 Alternatively give it when starting dovecot with -p parameter. Since
8494 this file is often world-readable, you may want to place this setting
8495 instead to a different.
8496 Defaults to @samp{""}.
8499 @deftypevr {@code{dovecot-configuration} parameter} string ssl-ca
8500 PEM encoded trusted certificate authority. Set this only if you
8501 intend to use @samp{ssl-verify-client-cert? #t}. The file should
8502 contain the CA certificate(s) followed by the matching
8503 CRL(s). (e.g. @samp{ssl-ca </etc/ssl/certs/ca.pem}).
8504 Defaults to @samp{""}.
8507 @deftypevr {@code{dovecot-configuration} parameter} boolean ssl-require-crl?
8508 Require that CRL check succeeds for client certificates.
8509 Defaults to @samp{#t}.
8512 @deftypevr {@code{dovecot-configuration} parameter} boolean ssl-verify-client-cert?
8513 Request client to send a certificate. If you also want to require
8514 it, set @samp{auth-ssl-require-client-cert? #t} in auth section.
8515 Defaults to @samp{#f}.
8518 @deftypevr {@code{dovecot-configuration} parameter} string ssl-cert-username-field
8519 Which field from certificate to use for username. commonName and
8520 x500UniqueIdentifier are the usual choices. You'll also need to set
8521 @samp{auth-ssl-username-from-cert? #t}.
8522 Defaults to @samp{"commonName"}.
8525 @deftypevr {@code{dovecot-configuration} parameter} hours ssl-parameters-regenerate
8526 How often to regenerate the SSL parameters file. Generation is
8527 quite CPU intensive operation. The value is in hours, 0 disables
8528 regeneration entirely.
8529 Defaults to @samp{168}.
8532 @deftypevr {@code{dovecot-configuration} parameter} string ssl-protocols
8533 SSL protocols to use.
8534 Defaults to @samp{"!SSLv2"}.
8537 @deftypevr {@code{dovecot-configuration} parameter} string ssl-cipher-list
8539 Defaults to @samp{"ALL:!LOW:!SSLv2:!EXP:!aNULL"}.
8542 @deftypevr {@code{dovecot-configuration} parameter} string ssl-crypto-device
8543 SSL crypto device to use, for valid values run "openssl engine".
8544 Defaults to @samp{""}.
8547 @deftypevr {@code{dovecot-configuration} parameter} string postmaster-address
8548 Address to use when sending rejection mails.
8549 Default is postmaster@@<your domain>. %d expands to recipient domain.
8550 Defaults to @samp{""}.
8553 @deftypevr {@code{dovecot-configuration} parameter} string hostname
8554 Hostname to use in various parts of sent mails (e.g. in Message-Id)
8555 and in LMTP replies. Default is the system's real hostname@@domain.
8556 Defaults to @samp{""}.
8559 @deftypevr {@code{dovecot-configuration} parameter} boolean quota-full-tempfail?
8560 If user is over quota, return with temporary failure instead of
8562 Defaults to @samp{#f}.
8565 @deftypevr {@code{dovecot-configuration} parameter} file-name sendmail-path
8566 Binary to use for sending mails.
8567 Defaults to @samp{"/usr/sbin/sendmail"}.
8570 @deftypevr {@code{dovecot-configuration} parameter} string submission-host
8571 If non-empty, send mails via this SMTP host[:port] instead of
8573 Defaults to @samp{""}.
8576 @deftypevr {@code{dovecot-configuration} parameter} string rejection-subject
8577 Subject: header to use for rejection mails. You can use the same
8578 variables as for @samp{rejection-reason} below.
8579 Defaults to @samp{"Rejected: %s"}.
8582 @deftypevr {@code{dovecot-configuration} parameter} string rejection-reason
8583 Human readable error message for rejection mails. You can use
8596 Defaults to @samp{"Your message to <%t> was automatically rejected:%n%r"}.
8599 @deftypevr {@code{dovecot-configuration} parameter} string recipient-delimiter
8600 Delimiter character between local-part and detail in email
8602 Defaults to @samp{"+"}.
8605 @deftypevr {@code{dovecot-configuration} parameter} string lda-original-recipient-header
8606 Header where the original recipient address (SMTP's RCPT TO:
8607 address) is taken from if not available elsewhere. With dovecot-lda -a
8608 parameter overrides this. A commonly used header for this is
8610 Defaults to @samp{""}.
8613 @deftypevr {@code{dovecot-configuration} parameter} boolean lda-mailbox-autocreate?
8614 Should saving a mail to a nonexistent mailbox automatically create
8616 Defaults to @samp{#f}.
8619 @deftypevr {@code{dovecot-configuration} parameter} boolean lda-mailbox-autosubscribe?
8620 Should automatically created mailboxes be also automatically
8622 Defaults to @samp{#f}.
8625 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer imap-max-line-length
8626 Maximum IMAP command line length. Some clients generate very long
8627 command lines with huge mailboxes, so you may need to raise this if you
8628 get "Too long argument" or "IMAP command line too large" errors
8630 Defaults to @samp{64000}.
8633 @deftypevr {@code{dovecot-configuration} parameter} string imap-logout-format
8634 IMAP logout format string:
8637 total number of bytes read from client
8639 total number of bytes sent to client.
8641 Defaults to @samp{"in=%i out=%o"}.
8644 @deftypevr {@code{dovecot-configuration} parameter} string imap-capability
8645 Override the IMAP CAPABILITY response. If the value begins with '+',
8646 add the given capabilities on top of the defaults (e.g. +XFOO XBAR).
8647 Defaults to @samp{""}.
8650 @deftypevr {@code{dovecot-configuration} parameter} string imap-idle-notify-interval
8651 How long to wait between "OK Still here" notifications when client
8653 Defaults to @samp{"2 mins"}.
8656 @deftypevr {@code{dovecot-configuration} parameter} string imap-id-send
8657 ID field names and values to send to clients. Using * as the value
8658 makes Dovecot use the default value. The following fields have default
8659 values currently: name, version, os, os-version, support-url,
8661 Defaults to @samp{""}.
8664 @deftypevr {@code{dovecot-configuration} parameter} string imap-id-log
8665 ID fields sent by client to log. * means everything.
8666 Defaults to @samp{""}.
8669 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list imap-client-workarounds
8670 Workarounds for various client bugs:
8674 Send EXISTS/RECENT new mail notifications only when replying to NOOP and
8675 CHECK commands. Some clients ignore them otherwise, for example OSX
8676 Mail (<v2.1). Outlook Express breaks more badly though, without this it
8677 may show user "Message no longer in server" errors. Note that OE6
8678 still breaks even with this workaround if synchronization is set to
8681 @item tb-extra-mailbox-sep
8682 Thunderbird gets somehow confused with LAYOUT=fs (mbox and dbox) and
8683 adds extra @samp{/} suffixes to mailbox names. This option causes Dovecot to
8684 ignore the extra @samp{/} instead of treating it as invalid mailbox name.
8687 Show \Noselect flags for LSUB replies with LAYOUT=fs (e.g. mbox).
8688 This makes Thunderbird realize they aren't selectable and show them
8689 greyed out, instead of only later giving "not selectable" popup error.
8691 Defaults to @samp{()}.
8694 @deftypevr {@code{dovecot-configuration} parameter} string imap-urlauth-host
8695 Host allowed in URLAUTH URLs sent by client. "*" allows all.
8696 Defaults to @samp{""}.
8700 Whew! Lots of configuration options. The nice thing about it though is
8701 that GuixSD has a complete interface to Dovecot's configuration
8702 language. This allows not only a nice way to declare configurations,
8703 but also offers reflective capabilities as well: users can write code to
8704 inspect and transform configurations from within Scheme.
8706 However, it could be that you just want to get a @code{dovecot.conf} up
8707 and running. In that case, you can pass an
8708 @code{opaque-dovecot-configuration} as the @code{#:config} paramter to
8709 @code{dovecot-service}. As its name indicates, an opaque configuration
8710 does not have easy reflective capabilities.
8712 Available @code{opaque-dovecot-configuration} fields are:
8714 @deftypevr {@code{opaque-dovecot-configuration} parameter} package dovecot
8715 The dovecot package.
8718 @deftypevr {@code{opaque-dovecot-configuration} parameter} string string
8719 The contents of the @code{dovecot.conf}, as a string.
8722 For example, if your @code{dovecot.conf} is just the empty string, you
8723 could instantiate a dovecot service like this:
8726 (dovecot-service #:config
8727 (opaque-dovecot-configuration
8732 @subsubsection Web Services
8734 The @code{(gnu services web)} module provides the following service:
8736 @deffn {Scheme Procedure} nginx-service [#:nginx nginx] @
8737 [#:log-directory ``/var/log/nginx''] @
8738 [#:run-directory ``/var/run/nginx''] @
8741 Return a service that runs @var{nginx}, the nginx web server.
8743 The nginx daemon loads its runtime configuration from @var{config-file}.
8744 Log files are written to @var{log-directory} and temporary runtime data
8745 files are written to @var{run-directory}. For proper operation, these
8746 arguments should match what is in @var{config-file} to ensure that the
8747 directories are created when the service is activated.
8751 @node Various Services
8752 @subsubsection Various Services
8754 The @code{(gnu services lirc)} module provides the following service.
8756 @deffn {Scheme Procedure} lirc-service [#:lirc lirc] @
8757 [#:device #f] [#:driver #f] [#:config-file #f] @
8758 [#:extra-options '()]
8759 Return a service that runs @url{http://www.lirc.org,LIRC}, a daemon that
8760 decodes infrared signals from remote controls.
8762 Optionally, @var{device}, @var{driver} and @var{config-file}
8763 (configuration file name) may be specified. See @command{lircd} manual
8766 Finally, @var{extra-options} is a list of additional command-line options
8767 passed to @command{lircd}.
8771 @node Setuid Programs
8772 @subsection Setuid Programs
8774 @cindex setuid programs
8775 Some programs need to run with ``root'' privileges, even when they are
8776 launched by unprivileged users. A notorious example is the
8777 @command{passwd} program, which users can run to change their
8778 password, and which needs to access the @file{/etc/passwd} and
8779 @file{/etc/shadow} files---something normally restricted to root, for
8780 obvious security reasons. To address that, these executables are
8781 @dfn{setuid-root}, meaning that they always run with root privileges
8782 (@pxref{How Change Persona,,, libc, The GNU C Library Reference Manual},
8783 for more info about the setuid mechanism.)
8785 The store itself @emph{cannot} contain setuid programs: that would be a
8786 security issue since any user on the system can write derivations that
8787 populate the store (@pxref{The Store}). Thus, a different mechanism is
8788 used: instead of changing the setuid bit directly on files that are in
8789 the store, we let the system administrator @emph{declare} which programs
8790 should be setuid root.
8792 The @code{setuid-programs} field of an @code{operating-system}
8793 declaration contains a list of G-expressions denoting the names of
8794 programs to be setuid-root (@pxref{Using the Configuration System}).
8795 For instance, the @command{passwd} program, which is part of the Shadow
8796 package, can be designated by this G-expression (@pxref{G-Expressions}):
8799 #~(string-append #$shadow "/bin/passwd")
8802 A default set of setuid programs is defined by the
8803 @code{%setuid-programs} variable of the @code{(gnu system)} module.
8805 @defvr {Scheme Variable} %setuid-programs
8806 A list of G-expressions denoting common programs that are setuid-root.
8808 The list includes commands such as @command{passwd}, @command{ping},
8809 @command{su}, and @command{sudo}.
8812 Under the hood, the actual setuid programs are created in the
8813 @file{/run/setuid-programs} directory at system activation time. The
8814 files in this directory refer to the ``real'' binaries, which are in the
8817 @node X.509 Certificates
8818 @subsection X.509 Certificates
8820 @cindex HTTPS, certificates
8821 @cindex X.509 certificates
8823 Web servers available over HTTPS (that is, HTTP over the transport-layer
8824 security mechanism, TLS) send client programs an @dfn{X.509 certificate}
8825 that the client can then use to @emph{authenticate} the server. To do
8826 that, clients verify that the server's certificate is signed by a
8827 so-called @dfn{certificate authority} (CA). But to verify the CA's
8828 signature, clients must have first acquired the CA's certificate.
8830 Web browsers such as GNU@tie{}IceCat include their own set of CA
8831 certificates, such that they are able to verify CA signatures
8834 However, most other programs that can talk HTTPS---@command{wget},
8835 @command{git}, @command{w3m}, etc.---need to be told where CA
8836 certificates can be found.
8838 @cindex @code{nss-certs}
8839 In GuixSD, this is done by adding a package that provides certificates
8840 to the @code{packages} field of the @code{operating-system} declaration
8841 (@pxref{operating-system Reference}). GuixSD includes one such package,
8842 @code{nss-certs}, which is a set of CA certificates provided as part of
8843 Mozilla's Network Security Services.
8845 Note that it is @emph{not} part of @var{%base-packages}, so you need to
8846 explicitly add it. The @file{/etc/ssl/certs} directory, which is where
8847 most applications and libraries look for certificates by default, points
8848 to the certificates installed globally.
8850 Unprivileged users can also install their own certificate package in
8851 their profile. A number of environment variables need to be defined so
8852 that applications and libraries know where to find them. Namely, the
8853 OpenSSL library honors the @code{SSL_CERT_DIR} and @code{SSL_CERT_FILE}
8854 variables. Some applications add their own environment variables; for
8855 instance, the Git version control system honors the certificate bundle
8856 pointed to by the @code{GIT_SSL_CAINFO} environment variable.
8859 @node Name Service Switch
8860 @subsection Name Service Switch
8862 @cindex name service switch
8864 The @code{(gnu system nss)} module provides bindings to the
8865 configuration file of libc's @dfn{name service switch} or @dfn{NSS}
8866 (@pxref{NSS Configuration File,,, libc, The GNU C Library Reference
8867 Manual}). In a nutshell, the NSS is a mechanism that allows libc to be
8868 extended with new ``name'' lookup methods for system databases, which
8869 includes host names, service names, user accounts, and more (@pxref{Name
8870 Service Switch, System Databases and Name Service Switch,, libc, The GNU
8871 C Library Reference Manual}).
8873 The NSS configuration specifies, for each system database, which lookup
8874 method is to be used, and how the various methods are chained
8875 together---for instance, under which circumstances NSS should try the
8876 next method in the list. The NSS configuration is given in the
8877 @code{name-service-switch} field of @code{operating-system} declarations
8878 (@pxref{operating-system Reference, @code{name-service-switch}}).
8881 @cindex .local, host name lookup
8882 As an example, the declaration below configures the NSS to use the
8883 @uref{http://0pointer.de/lennart/projects/nss-mdns/, @code{nss-mdns}
8884 back-end}, which supports host name lookups over multicast DNS (mDNS)
8885 for host names ending in @code{.local}:
8888 (name-service-switch
8889 (hosts (list %files ;first, check /etc/hosts
8891 ;; If the above did not succeed, try
8892 ;; with 'mdns_minimal'.
8894 (name "mdns_minimal")
8896 ;; 'mdns_minimal' is authoritative for
8897 ;; '.local'. When it returns "not found",
8898 ;; no need to try the next methods.
8899 (reaction (lookup-specification
8900 (not-found => return))))
8902 ;; Then fall back to DNS.
8906 ;; Finally, try with the "full" 'mdns'.
8911 Don't worry: the @code{%mdns-host-lookup-nss} variable (see below)
8912 contains this configuration, so you won't have to type it if all you
8913 want is to have @code{.local} host lookup working.
8915 Note that, in this case, in addition to setting the
8916 @code{name-service-switch} of the @code{operating-system} declaration,
8917 you also need to use @code{avahi-service} (@pxref{Networking Services,
8918 @code{avahi-service}}), or @var{%desktop-services}, which includes it
8919 (@pxref{Desktop Services}). Doing this makes @code{nss-mdns} accessible
8920 to the name service cache daemon (@pxref{Base Services,
8921 @code{nscd-service}}).
8923 For convenience, the following variables provide typical NSS
8926 @defvr {Scheme Variable} %default-nss
8927 This is the default name service switch configuration, a
8928 @code{name-service-switch} object.
8931 @defvr {Scheme Variable} %mdns-host-lookup-nss
8932 This is the name service switch configuration with support for host name
8933 lookup over multicast DNS (mDNS) for host names ending in @code{.local}.
8936 The reference for name service switch configuration is given below. It
8937 is a direct mapping of the C library's configuration file format, so
8938 please refer to the C library manual for more information (@pxref{NSS
8939 Configuration File,,, libc, The GNU C Library Reference Manual}).
8940 Compared to libc's NSS configuration file format, it has the advantage
8941 not only of adding this warm parenthetic feel that we like, but also
8942 static checks: you'll know about syntax errors and typos as soon as you
8943 run @command{guix system}.
8945 @deftp {Data Type} name-service-switch
8947 This is the data type representation the configuration of libc's name
8948 service switch (NSS). Each field below represents one of the supported
8965 The system databases handled by the NSS. Each of these fields must be a
8966 list of @code{<name-service>} objects (see below.)
8970 @deftp {Data Type} name-service
8972 This is the data type representing an actual name service and the
8973 associated lookup action.
8977 A string denoting the name service (@pxref{Services in the NSS
8978 configuration,,, libc, The GNU C Library Reference Manual}).
8980 Note that name services listed here must be visible to nscd. This is
8981 achieved by passing the @code{#:name-services} argument to
8982 @code{nscd-service} the list of packages providing the needed name
8983 services (@pxref{Base Services, @code{nscd-service}}).
8986 An action specified using the @code{lookup-specification} macro
8987 (@pxref{Actions in the NSS configuration,,, libc, The GNU C Library
8988 Reference Manual}). For example:
8991 (lookup-specification (unavailable => continue)
8992 (success => return))
8997 @node Initial RAM Disk
8998 @subsection Initial RAM Disk
9000 @cindex initial RAM disk (initrd)
9001 @cindex initrd (initial RAM disk)
9002 For bootstrapping purposes, the Linux-Libre kernel is passed an
9003 @dfn{initial RAM disk}, or @dfn{initrd}. An initrd contains a temporary
9004 root file system, as well as an initialization script. The latter is
9005 responsible for mounting the real root file system, and for loading any
9006 kernel modules that may be needed to achieve that.
9008 The @code{initrd} field of an @code{operating-system} declaration allows
9009 you to specify which initrd you would like to use. The @code{(gnu
9010 system linux-initrd)} module provides two ways to build an initrd: the
9011 high-level @code{base-initrd} procedure, and the low-level
9012 @code{expression->initrd} procedure.
9014 The @code{base-initrd} procedure is intended to cover most common uses.
9015 For example, if you want to add a bunch of kernel modules to be loaded
9016 at boot time, you can define the @code{initrd} field of the operating
9017 system declaration like this:
9020 (initrd (lambda (file-systems . rest)
9021 ;; Create a standard initrd that has modules "foo.ko"
9022 ;; and "bar.ko", as well as their dependencies, in
9023 ;; addition to the modules available by default.
9024 (apply base-initrd file-systems
9025 #:extra-modules '("foo" "bar")
9029 The @code{base-initrd} procedure also handles common use cases that
9030 involves using the system as a QEMU guest, or as a ``live'' system whose
9031 root file system is volatile.
9033 The initial RAM disk produced by @code{base-initrd} honors several
9034 options passed on the Linux kernel command line (that is, arguments
9035 passed @i{via} GRUB's @code{linux} command, or with QEMU's
9036 @code{-append} option), notably:
9039 @item --load=@var{boot}
9040 Tell the initial RAM disk to load @var{boot}, a file containing a Scheme
9041 program, once it has mounted the root file system.
9043 GuixSD uses this option to yield control to a boot program that runs the
9044 service activation programs and then spawns the GNU@tie{}Shepherd, the
9045 initialization system.
9047 @item --root=@var{root}
9048 Mount @var{root} as the root file system. @var{root} can be a device
9049 device name like @code{/dev/sda1}, a partition label, or a partition
9052 @item --system=@var{system}
9053 Have @file{/run/booted-system} and @file{/run/current-system} point to
9056 @item modprobe.blacklist=@var{modules}@dots{}
9057 @cindex module, black-listing
9058 @cindex black list, of kernel modules
9059 Instruct the initial RAM disk as well as the @command{modprobe} command
9060 (from the kmod package) to refuse to load @var{modules}. @var{modules}
9061 must be a comma-separated list of module names---e.g.,
9062 @code{usbkbd,9pnet}.
9065 Start a read-eval-print loop (REPL) from the initial RAM disk before it
9066 tries to load kernel modules and to mount the root file system. Our
9067 marketing team calls it @dfn{boot-to-Guile}. The Schemer in you will
9068 love it. @xref{Using Guile Interactively,,, guile, GNU Guile Reference
9069 Manual}, for more information on Guile's REPL.
9073 Now that you know all the features that initial RAM disks produced by
9074 @code{base-initrd} provide, here is how to use it and customize it
9077 @deffn {Monadic Procedure} base-initrd @var{file-systems} @
9078 [#:qemu-networking? #f] [#:virtio? #t] [#:volatile-root? #f] @
9079 [#:extra-modules '()] [#:mapped-devices '()]
9080 Return a monadic derivation that builds a generic initrd. @var{file-systems} is
9081 a list of file-systems to be mounted by the initrd, possibly in addition to
9082 the root file system specified on the kernel command line via @code{--root}.
9083 @var{mapped-devices} is a list of device mappings to realize before
9084 @var{file-systems} are mounted (@pxref{Mapped Devices}).
9086 When @var{qemu-networking?} is true, set up networking with the standard QEMU
9087 parameters. When @var{virtio?} is true, load additional modules so the initrd can
9088 be used as a QEMU guest with para-virtualized I/O drivers.
9090 When @var{volatile-root?} is true, the root file system is writable but any changes
9093 The initrd is automatically populated with all the kernel modules necessary
9094 for @var{file-systems} and for the given options. However, additional kernel
9095 modules can be listed in @var{extra-modules}. They will be added to the initrd, and
9096 loaded at boot time in the order in which they appear.
9099 Needless to say, the initrds we produce and use embed a
9100 statically-linked Guile, and the initialization program is a Guile
9101 program. That gives a lot of flexibility. The
9102 @code{expression->initrd} procedure builds such an initrd, given the
9103 program to run in that initrd.
9105 @deffn {Monadic Procedure} expression->initrd @var{exp} @
9106 [#:guile %guile-static-stripped] [#:name "guile-initrd"] @
9108 Return a derivation that builds a Linux initrd (a gzipped cpio archive)
9109 containing @var{guile} and that evaluates @var{exp}, a G-expression,
9110 upon booting. All the derivations referenced by @var{exp} are
9111 automatically copied to the initrd.
9113 @var{modules} is a list of Guile module names to be embedded in the
9117 @node GRUB Configuration
9118 @subsection GRUB Configuration
9123 The operating system uses GNU@tie{}GRUB as its boot loader
9124 (@pxref{Overview, overview of GRUB,, grub, GNU GRUB Manual}). It is
9125 configured using @code{grub-configuration} declarations. This data type
9126 is exported by the @code{(gnu system grub)} module, and described below.
9128 @deftp {Data Type} grub-configuration
9129 The type of a GRUB configuration declaration.
9134 This is a string denoting the boot device. It must be a device name
9135 understood by the @command{grub-install} command, such as
9136 @code{/dev/sda} or @code{(hd0)} (@pxref{Invoking grub-install,,, grub,
9139 @item @code{menu-entries} (default: @code{()})
9140 A possibly empty list of @code{menu-entry} objects (see below), denoting
9141 entries to appear in the GRUB boot menu, in addition to the current
9142 system entry and the entry pointing to previous system generations.
9144 @item @code{default-entry} (default: @code{0})
9145 The index of the default boot menu entry. Index 0 is for the current
9148 @item @code{timeout} (default: @code{5})
9149 The number of seconds to wait for keyboard input before booting. Set to
9150 0 to boot immediately, and to -1 to wait indefinitely.
9152 @item @code{theme} (default: @var{%default-theme})
9153 The @code{grub-theme} object describing the theme to use.
9158 Should you want to list additional boot menu entries @i{via} the
9159 @code{menu-entries} field above, you will need to create them with the
9160 @code{menu-entry} form:
9162 @deftp {Data Type} menu-entry
9163 The type of an entry in the GRUB boot menu.
9168 The label to show in the menu---e.g., @code{"GNU"}.
9171 The Linux kernel to boot.
9173 @item @code{linux-arguments} (default: @code{()})
9174 The list of extra Linux kernel command-line arguments---e.g.,
9175 @code{("console=ttyS0")}.
9178 A G-Expression or string denoting the file name of the initial RAM disk
9179 to use (@pxref{G-Expressions}).
9184 @c FIXME: Write documentation once it's stable.
9185 Themes are created using the @code{grub-theme} form, which is not
9188 @defvr {Scheme Variable} %default-theme
9189 This is the default GRUB theme used by the operating system, with a
9190 fancy background image displaying the GNU and Guix logos.
9194 @node Invoking guix system
9195 @subsection Invoking @code{guix system}
9197 Once you have written an operating system declaration, as seen in the
9198 previous section, it can be @dfn{instantiated} using the @command{guix
9199 system} command. The synopsis is:
9202 guix system @var{options}@dots{} @var{action} @var{file}
9205 @var{file} must be the name of a file containing an
9206 @code{operating-system} declaration. @var{action} specifies how the
9207 operating system is instantiate. Currently the following values are
9212 Build the operating system described in @var{file}, activate it, and
9213 switch to it@footnote{This action is usable only on systems already
9216 This effects all the configuration specified in @var{file}: user
9217 accounts, system services, global package list, setuid programs, etc.
9218 The command starts system services specified in @var{file} that are not
9219 currently running; if a service is currently running, it does not
9220 attempt to upgrade it since it would not be possible without stopping it
9223 It also adds a GRUB menu entry for the new OS configuration, and moves
9224 entries for older configurations to a submenu---unless
9225 @option{--no-grub} is passed.
9228 @c The paragraph below refers to the problem discussed at
9229 @c <http://lists.gnu.org/archive/html/guix-devel/2014-08/msg00057.html>.
9230 It is highly recommended to run @command{guix pull} once before you run
9231 @command{guix system reconfigure} for the first time (@pxref{Invoking
9232 guix pull}). Failing to do that you would see an older version of Guix
9233 once @command{reconfigure} has completed.
9237 Build the operating system's derivation, which includes all the
9238 configuration files and programs needed to boot and run the system.
9239 This action does not actually install anything.
9242 Populate the given directory with all the files necessary to run the
9243 operating system specified in @var{file}. This is useful for first-time
9244 installations of GuixSD. For instance:
9247 guix system init my-os-config.scm /mnt
9250 copies to @file{/mnt} all the store items required by the configuration
9251 specified in @file{my-os-config.scm}. This includes configuration
9252 files, packages, and so on. It also creates other essential files
9253 needed for the system to operate correctly---e.g., the @file{/etc},
9254 @file{/var}, and @file{/run} directories, and the @file{/bin/sh} file.
9256 This command also installs GRUB on the device specified in
9257 @file{my-os-config}, unless the @option{--no-grub} option was passed.
9260 @cindex virtual machine
9262 @anchor{guix system vm}
9263 Build a virtual machine that contain the operating system declared in
9264 @var{file}, and return a script to run that virtual machine (VM).
9265 Arguments given to the script are passed as is to QEMU.
9267 The VM shares its store with the host system.
9269 Additional file systems can be shared between the host and the VM using
9270 the @code{--share} and @code{--expose} command-line options: the former
9271 specifies a directory to be shared with write access, while the latter
9272 provides read-only access to the shared directory.
9274 The example below creates a VM in which the user's home directory is
9275 accessible read-only, and where the @file{/exchange} directory is a
9276 read-write mapping of the host's @file{$HOME/tmp}:
9279 guix system vm my-config.scm \
9280 --expose=$HOME --share=$HOME/tmp=/exchange
9283 On GNU/Linux, the default is to boot directly to the kernel; this has
9284 the advantage of requiring only a very tiny root disk image since the
9285 host's store can then be mounted.
9287 The @code{--full-boot} option forces a complete boot sequence, starting
9288 with the bootloader. This requires more disk space since a root image
9289 containing at least the kernel, initrd, and bootloader data files must
9290 be created. The @code{--image-size} option can be used to specify the
9295 Return a virtual machine or disk image of the operating system declared
9296 in @var{file} that stands alone. Use the @option{--image-size} option
9297 to specify the size of the image.
9299 When using @code{vm-image}, the returned image is in qcow2 format, which
9300 the QEMU emulator can efficiently use. @xref{Running GuixSD in a VM},
9301 for more information on how to run the image in a virtual machine.
9303 When using @code{disk-image}, a raw disk image is produced; it can be
9304 copied as is to a USB stick, for instance. Assuming @code{/dev/sdc} is
9305 the device corresponding to a USB stick, one can copy the image on it
9306 using the following command:
9309 # dd if=$(guix system disk-image my-os.scm) of=/dev/sdc
9313 Return a script to run the operating system declared in @var{file}
9314 within a container. Containers are a set of lightweight isolation
9315 mechanisms provided by the kernel Linux-libre. Containers are
9316 substantially less resource-demanding than full virtual machines since
9317 the kernel, shared objects, and other resources can be shared with the
9318 host system; this also means they provide thinner isolation.
9320 Currently, the script must be run as root in order to support more than
9321 a single user and group. The container shares its store with the host
9324 As with the @code{vm} action (@pxref{guix system vm}), additional file
9325 systems to be shared between the host and container can be specified
9326 using the @option{--share} and @option{--expose} options:
9329 guix system container my-config.scm \
9330 --expose=$HOME --share=$HOME/tmp=/exchange
9334 This option requires Linux-libre 3.19 or newer.
9339 @var{options} can contain any of the common build options (@pxref{Common
9340 Build Options}). In addition, @var{options} can contain one of the
9344 @item --system=@var{system}
9345 @itemx -s @var{system}
9346 Attempt to build for @var{system} instead of the host's system type.
9347 This works as per @command{guix build} (@pxref{Invoking guix build}).
9351 Return the derivation file name of the given operating system without
9354 @item --image-size=@var{size}
9355 For the @code{vm-image} and @code{disk-image} actions, create an image
9356 of the given @var{size}. @var{size} may be a number of bytes, or it may
9357 include a unit as a suffix (@pxref{Block size, size specifications,,
9358 coreutils, GNU Coreutils}).
9360 @item --on-error=@var{strategy}
9361 Apply @var{strategy} when an error occurs when reading @var{file}.
9362 @var{strategy} may be one of the following:
9365 @item nothing-special
9366 Report the error concisely and exit. This is the default strategy.
9369 Likewise, but also display a backtrace.
9372 Report the error and enter Guile's debugger. From there, you can run
9373 commands such as @code{,bt} to get a backtrace, @code{,locals} to
9374 display local variable values, and more generally inspect the program's
9375 state. @xref{Debug Commands,,, guile, GNU Guile Reference Manual}, for
9376 a list of available debugging commands.
9380 Note that all the actions above, except @code{build} and @code{init},
9381 rely on KVM support in the Linux-Libre kernel. Specifically, the
9382 machine should have hardware virtualization support, the corresponding
9383 KVM kernel module should be loaded, and the @file{/dev/kvm} device node
9384 must exist and be readable and writable by the user and by the daemon's
9387 Once you have built, configured, re-configured, and re-re-configured
9388 your GuixSD installation, you may find it useful to list the operating
9389 system generations available on disk---and that you can choose from the
9394 @item list-generations
9395 List a summary of each generation of the operating system available on
9396 disk, in a human-readable way. This is similar to the
9397 @option{--list-generations} option of @command{guix package}
9398 (@pxref{Invoking guix package}).
9400 Optionally, one can specify a pattern, with the same syntax that is used
9401 in @command{guix package --list-generations}, to restrict the list of
9402 generations displayed. For instance, the following command displays
9403 generations up to 10-day old:
9406 $ guix system list-generations 10d
9411 The @command{guix system} command has even more to offer! The following
9412 sub-commands allow you to visualize how your system services relate to
9415 @anchor{system-extension-graph}
9418 @item extension-graph
9419 Emit in Dot/Graphviz format to standard output the @dfn{service
9420 extension graph} of the operating system defined in @var{file}
9421 (@pxref{Service Composition}, for more information on service
9427 $ guix system extension-graph @var{file} | dot -Tpdf > services.pdf
9430 produces a PDF file showing the extension relations among services.
9432 @anchor{system-shepherd-graph}
9433 @item shepherd-graph
9434 Emit in Dot/Graphviz format to standard output the @dfn{dependency
9435 graph} of shepherd services of the operating system defined in
9436 @var{file}. @xref{Shepherd Services}, for more information and for an
9441 @node Running GuixSD in a VM
9442 @subsection Running GuixSD in a virtual machine
9444 One way to run GuixSD in a virtual machine (VM) is to build a GuixSD
9445 virtual machine image using @command{guix system vm-image}
9446 (@pxref{Invoking guix system}). The returned image is in qcow2 format,
9447 which the @uref{http://qemu.org/, QEMU emulator} can efficiently use.
9449 To run the image in QEMU, copy it out of the store (@pxref{The Store})
9450 and give yourself permission to write to the copy. When invoking QEMU,
9451 you must choose a system emulator that is suitable for your hardware
9452 platform. Here is a minimal QEMU invocation that will boot the result
9453 of @command{guix system vm-image} on x86_64 hardware:
9456 $ qemu-system-x86_64 \
9457 -net user -net nic,model=virtio \
9458 -enable-kvm -m 256 /tmp/qemu-image
9461 Here is what each of these options means:
9464 @item qemu-system-x86_64
9465 This specifies the hardware platform to emulate. This should match the
9469 Enable the unprivileged user-mode network stack. The guest OS can
9470 access the host but not vice versa. This is the simplest way to get the
9471 guest OS online. If you don't choose a network stack, the boot will
9474 @item -net nic,model=virtio
9475 You must create a network interface of a given model. If you don't
9476 create a NIC, the boot will fail. Assuming your hardware platform is
9477 x86_64, you can get a list of available NIC models by running
9478 @command{qemu-system-x86_64 -net nic,model=help}.
9481 If your system has hardware virtualization extensions, enabling the
9482 Linux kernel's virtual machine support (KVM) will make things run
9486 RAM available to the guest OS, in mebibytes. Defaults to 128@tie{}MiB,
9487 which may be insufficent for some operations.
9489 @item /tmp/qemu-image
9490 The file name of the qcow2 image.
9493 @node Defining Services
9494 @subsection Defining Services
9496 The previous sections show the available services and how one can combine
9497 them in an @code{operating-system} declaration. But how do we define
9498 them in the first place? And what is a service anyway?
9501 * Service Composition:: The model for composing services.
9502 * Service Types and Services:: Types and services.
9503 * Service Reference:: API reference.
9504 * Shepherd Services:: A particular type of service.
9507 @node Service Composition
9508 @subsubsection Service Composition
9512 Here we define a @dfn{service} as, broadly, something that extends the
9513 operating system's functionality. Often a service is a process---a
9514 @dfn{daemon}---started when the system boots: a secure shell server, a
9515 Web server, the Guix build daemon, etc. Sometimes a service is a daemon
9516 whose execution can be triggered by another daemon---e.g., an FTP server
9517 started by @command{inetd} or a D-Bus service activated by
9518 @command{dbus-daemon}. Occasionally, a service does not map to a
9519 daemon. For instance, the ``account'' service collects user accounts
9520 and makes sure they exist when the system runs; the ``udev'' service
9521 collects device management rules and makes them available to the eudev
9522 daemon; the @file{/etc} service populates the system's @file{/etc}
9525 @cindex service extensions
9526 GuixSD services are connected by @dfn{extensions}. For instance, the
9527 secure shell service @emph{extends} the Shepherd---GuixSD's
9528 initialization system, running as PID@tie{}1---by giving it the command
9529 lines to start and stop the secure shell daemon (@pxref{Networking
9530 Services, @code{lsh-service}}); the UPower service extends the D-Bus
9531 service by passing it its @file{.service} specification, and extends the
9532 udev service by passing it device management rules (@pxref{Desktop
9533 Services, @code{upower-service}}); the Guix daemon service extends the
9534 Shepherd by passing it the command lines to start and stop the daemon,
9535 and extends the account service by passing it a list of required build
9536 user accounts (@pxref{Base Services}).
9538 All in all, services and their ``extends'' relations form a directed
9539 acyclic graph (DAG). If we represent services as boxes and extensions
9540 as arrows, a typical system might provide something like this:
9542 @image{images/service-graph,,5in,Typical service extension graph.}
9544 @cindex system service
9545 At the bottom, we see the @dfn{system service}, which produces the
9546 directory containing everything to run and boot the system, as returned
9547 by the @command{guix system build} command. @xref{Service Reference},
9548 to learn about the other service types shown here.
9549 @xref{system-extension-graph, the @command{guix system extension-graph}
9550 command}, for information on how to generate this representation for a
9551 particular operating system definition.
9553 @cindex service types
9554 Technically, developers can define @dfn{service types} to express these
9555 relations. There can be any number of services of a given type on the
9556 system---for instance, a system running two instances of the GNU secure
9557 shell server (lsh) has two instances of @var{lsh-service-type}, with
9558 different parameters.
9560 The following section describes the programming interface for service
9563 @node Service Types and Services
9564 @subsubsection Service Types and Services
9566 A @dfn{service type} is a node in the DAG described above. Let us start
9567 with a simple example, the service type for the Guix build daemon
9568 (@pxref{Invoking guix-daemon}):
9571 (define guix-service-type
9575 (list (service-extension shepherd-root-service-type guix-shepherd-service)
9576 (service-extension account-service-type guix-accounts)
9577 (service-extension activation-service-type guix-activation)))))
9581 It defines a two things:
9585 A name, whose sole purpose is to make inspection and debugging easier.
9588 A list of @dfn{service extensions}, where each extension designates the
9589 target service type and a procedure that, given the service's
9590 parameters, returns a list of object to extend the service of that type.
9592 Every service type has at least one service extension. The only
9593 exception is the @dfn{boot service type}, which is the ultimate service.
9596 In this example, @var{guix-service-type} extends three services:
9599 @item shepherd-root-service-type
9600 The @var{guix-shepherd-service} procedure defines how the Shepherd
9601 service is extended. Namely, it returns a @code{<shepherd-service>}
9602 object that defines how @command{guix-daemon} is started and stopped
9603 (@pxref{Shepherd Services}).
9605 @item account-service-type
9606 This extension for this service is computed by @var{guix-accounts},
9607 which returns a list of @code{user-group} and @code{user-account}
9608 objects representing the build user accounts (@pxref{Invoking
9611 @item activation-service-type
9612 Here @var{guix-activation} is a procedure that returns a gexp, which is
9613 a code snippet to run at ``activation time''---e.g., when the service is
9617 A service of this type is instantiated like this:
9620 (service guix-service-type
9623 (use-substitutes? #f)))
9626 The second argument to the @code{service} form is a value representing
9627 the parameters of this specific service instance.
9628 @xref{guix-configuration-type, @code{guix-configuration}}, for
9629 information about the @code{guix-configuration} data type.
9631 @var{guix-service-type} is quite simple because it extends other
9632 services but is not extensible itself.
9634 @c @subsubsubsection Extensible Service Types
9636 The service type for an @emph{extensible} service looks like this:
9639 (define udev-service-type
9640 (service-type (name 'udev)
9642 (list (service-extension shepherd-root-service-type
9643 udev-shepherd-service)))
9645 (compose concatenate) ;concatenate the list of rules
9646 (extend (lambda (config rules)
9648 (($ <udev-configuration> udev initial-rules)
9650 (udev udev) ;the udev package to use
9651 (rules (append initial-rules rules)))))))))
9654 This is the service type for the
9655 @uref{https://wiki.gentoo.org/wiki/Project:Eudev, eudev device
9656 management daemon}. Compared to the previous example, in addition to an
9657 extension of @var{shepherd-root-service-type}, we see two new fields:
9661 This is the procedure to @dfn{compose} the list of extensions to
9662 services of this type.
9664 Services can extend the udev service by passing it lists of rules; we
9665 compose those extensions simply by concatenating them.
9668 This procedure defines how the service's value is @dfn{extended} with
9669 the composition of the extensions.
9671 Udev extensions are composed into a list of rules, but the udev service
9672 value is itself a @code{<udev-configuration>} record. So here, we
9673 extend that record by appending the list of rules is contains to the
9674 list of contributed rules.
9677 There can be only one instance of an extensible service type such as
9678 @var{udev-service-type}. If there were more, the
9679 @code{service-extension} specifications would be ambiguous.
9681 Still here? The next section provides a reference of the programming
9682 interface for services.
9684 @node Service Reference
9685 @subsubsection Service Reference
9687 We have seen an overview of service types (@pxref{Service Types and
9688 Services}). This section provides a reference on how to manipulate
9689 services and service types. This interface is provided by the
9690 @code{(gnu services)} module.
9692 @deffn {Scheme Procedure} service @var{type} @var{value}
9693 Return a new service of @var{type}, a @code{<service-type>} object (see
9694 below.) @var{value} can be any object; it represents the parameters of
9695 this particular service instance.
9698 @deffn {Scheme Procedure} service? @var{obj}
9699 Return true if @var{obj} is a service.
9702 @deffn {Scheme Procedure} service-kind @var{service}
9703 Return the type of @var{service}---i.e., a @code{<service-type>} object.
9706 @deffn {Scheme Procedure} service-parameters @var{service}
9707 Return the value associated with @var{service}. It represents its
9711 Here is an example of how a service is created and manipulated:
9715 (service nginx-service-type
9716 (nginx-configuration
9718 (log-directory log-directory)
9719 (run-directory run-directory)
9720 (file config-file))))
9725 (eq? (service-kind s) nginx-service-type)
9729 The @code{modify-services} form provides a handy way to change the
9730 parameters of some of the services of a list such as
9731 @var{%base-services} (@pxref{Base Services, @code{%base-services}}). Of
9732 course, you could always use standard list combinators such as
9733 @code{map} and @code{fold} to do that (@pxref{SRFI-1, List Library,,
9734 guile, GNU Guile Reference Manual}); @code{modify-services} simply
9735 provides a more concise form for this common pattern.
9737 @deffn {Scheme Syntax} modify-services @var{services} @
9738 (@var{type} @var{variable} => @var{body}) @dots{}
9740 Modify the services listed in @var{services} according to the given
9741 clauses. Each clause has the form:
9744 (@var{type} @var{variable} => @var{body})
9747 where @var{type} is a service type, such as @var{guix-service-type}, and
9748 @var{variable} is an identifier that is bound within @var{body} to the
9749 value of the service of that @var{type}. @xref{Using the Configuration
9750 System}, for an example.
9752 This is a shorthand for:
9755 (map (lambda (service) @dots{}) @var{services})
9759 Next comes the programming interface for service types. This is
9760 something you want to know when writing new service definitions, but not
9761 necessarily when simply looking for ways to customize your
9762 @code{operating-system} declaration.
9764 @deftp {Data Type} service-type
9765 @cindex service type
9766 This is the representation of a @dfn{service type} (@pxref{Service Types
9771 This is a symbol, used only to simplify inspection and debugging.
9773 @item @code{extensions}
9774 A non-empty list of @code{<service-extension>} objects (see below.)
9776 @item @code{compose} (default: @code{#f})
9777 If this is @code{#f}, then the service type denotes services that cannot
9778 be extended---i.e., services that do not receive ``values'' from other
9781 Otherwise, it must be a one-argument procedure. The procedure is called
9782 by @code{fold-services} and is passed a list of values collected from
9783 extensions. It must return a value that is a valid parameter value for
9784 the service instance.
9786 @item @code{extend} (default: @code{#f})
9787 If this is @code{#f}, services of this type cannot be extended.
9789 Otherwise, it must be a two-argument procedure: @code{fold-services}
9790 calls it, passing it the service's initial value as the first argument
9791 and the result of applying @code{compose} to the extension values as the
9795 @xref{Service Types and Services}, for examples.
9798 @deffn {Scheme Procedure} service-extension @var{target-type} @
9800 Return a new extension for services of type @var{target-type}.
9801 @var{compute} must be a one-argument procedure: @code{fold-services}
9802 calls it, passing it the value associated with the service that provides
9803 the extension; it must return a valid value for the target service.
9806 @deffn {Scheme Procedure} service-extension? @var{obj}
9807 Return true if @var{obj} is a service extension.
9810 At the core of the service abstraction lies the @code{fold-services}
9811 procedure, which is responsible for ``compiling'' a list of services
9812 down to a single directory that contains everything needed to boot and
9813 run the system---the directory shown by the @command{guix system build}
9814 command (@pxref{Invoking guix system}). In essence, it propagates
9815 service extensions down the service graph, updating each node parameters
9816 on the way, until it reaches the root node.
9818 @deffn {Scheme Procedure} fold-services @var{services} @
9819 [#:target-type @var{system-service-type}]
9820 Fold @var{services} by propagating their extensions down to the root of
9821 type @var{target-type}; return the root service adjusted accordingly.
9824 Lastly, the @code{(gnu services)} module also defines several essential
9825 service types, some of which are listed below.
9827 @defvr {Scheme Variable} system-service-type
9828 This is the root of the service graph. It produces the system directory
9829 as returned by the @command{guix system build} command.
9832 @defvr {Scheme Variable} boot-service-type
9833 The type of the ``boot service'', which produces the @dfn{boot script}.
9834 The boot script is what the initial RAM disk runs when booting.
9837 @defvr {Scheme Variable} etc-service-type
9838 The type of the @file{/etc} service. This service can be extended by
9839 passing it name/file tuples such as:
9842 (list `("issue" ,(plain-file "issue" "Welcome!\n")))
9845 In this example, the effect would be to add an @file{/etc/issue} file
9846 pointing to the given file.
9849 @defvr {Scheme Variable} setuid-program-service-type
9850 Type for the ``setuid-program service''. This service collects lists of
9851 executable file names, passed as gexps, and adds them to the set of
9852 setuid-root programs on the system (@pxref{Setuid Programs}).
9855 @defvr {Scheme Variable} profile-service-type
9856 Type of the service that populates the @dfn{system profile}---i.e., the
9857 programs under @file{/run/current-system/profile}. Other services can
9858 extend it by passing it lists of packages to add to the system profile.
9862 @node Shepherd Services
9863 @subsubsection Shepherd Services
9867 The @code{(gnu services shepherd)} provides a way to define services
9868 managed by the GNU@tie{}Shepherd, which is GuixSD initialization
9869 system---the first process that is started when the system boots,
9870 aka. PID@tie{}1 (@pxref{Introduction,,, shepherd, The GNU Shepherd
9873 Services in the Shepherd can depend on each other. For instance, the
9874 SSH daemon may need to be started after the syslog daemon has been
9875 started, which in turn can only happen once all the file systems have
9876 been mounted. The simple operating system defined earlier (@pxref{Using
9877 the Configuration System}) results in a service graph like this:
9879 @image{images/shepherd-graph,,5in,Typical shepherd service graph.}
9881 You can actually generate such a graph for any operating system
9882 definition using the @command{guix system shepherd-graph} command
9883 (@pxref{system-shepherd-graph, @command{guix system shepherd-graph}}).
9885 The @var{%shepherd-root-service} is a service object representing
9886 PID@tie{}1, of type @var{shepherd-root-service-type}; it can be extended
9887 by passing it lists of @code{<shepherd-service>} objects.
9889 @deftp {Data Type} shepherd-service
9890 The data type representing a service managed by the Shepherd.
9893 @item @code{provision}
9894 This is a list of symbols denoting what the service provides.
9896 These are the names that may be passed to @command{herd start},
9897 @command{herd status}, and similar commands (@pxref{Invoking herd,,,
9898 shepherd, The GNU Shepherd Manual}). @xref{Slots of services, the
9899 @code{provides} slot,, shepherd, The GNU Shepherd Manual}, for details.
9901 @item @code{requirements} (default: @code{'()})
9902 List of symbols denoting the Shepherd services this one depends on.
9904 @item @code{respawn?} (default: @code{#t})
9905 Whether to restart the service when it stops, for instance when the
9906 underlying process dies.
9909 @itemx @code{stop} (default: @code{#~(const #f)})
9910 The @code{start} and @code{stop} fields refer to the Shepherd's
9911 facilities to start and stop processes (@pxref{Service De- and
9912 Constructors,,, shepherd, The GNU Shepherd Manual}). They are given as
9913 G-expressions that get expanded in the Shepherd configuration file
9914 (@pxref{G-Expressions}).
9916 @item @code{documentation}
9917 A documentation string, as shown when running:
9920 herd doc @var{service-name}
9923 where @var{service-name} is one of the symbols in @var{provision}
9924 (@pxref{Invoking herd,,, shepherd, The GNU Shepherd Manual}).
9926 @item @code{modules} (default: @var{%default-modules})
9927 This is the list of modules that must be in scope when @code{start} and
9928 @code{stop} are evaluated.
9930 @item @code{imported-modules} (default: @var{%default-imported-modules})
9931 This is the list of modules to import in the execution environment of
9937 @defvr {Scheme Variable} shepherd-root-service-type
9938 The service type for the Shepherd ``root service''---i.e., PID@tie{}1.
9940 This is the service type that extensions target when they want to create
9941 shepherd services (@pxref{Service Types and Services}, for an example).
9942 Each extension must pass a list of @code{<shepherd-service>}.
9945 @defvr {Scheme Variable} %shepherd-root-service
9946 This service represents PID@tie{}1.
9950 @node Installing Debugging Files
9951 @section Installing Debugging Files
9953 @cindex debugging files
9954 Program binaries, as produced by the GCC compilers for instance, are
9955 typically written in the ELF format, with a section containing
9956 @dfn{debugging information}. Debugging information is what allows the
9957 debugger, GDB, to map binary code to source code; it is required to
9958 debug a compiled program in good conditions.
9960 The problem with debugging information is that is takes up a fair amount
9961 of disk space. For example, debugging information for the GNU C Library
9962 weighs in at more than 60 MiB. Thus, as a user, keeping all the
9963 debugging info of all the installed programs is usually not an option.
9964 Yet, space savings should not come at the cost of an impediment to
9965 debugging---especially in the GNU system, which should make it easier
9966 for users to exert their computing freedom (@pxref{GNU Distribution}).
9968 Thankfully, the GNU Binary Utilities (Binutils) and GDB provide a
9969 mechanism that allows users to get the best of both worlds: debugging
9970 information can be stripped from the binaries and stored in separate
9971 files. GDB is then able to load debugging information from those files,
9972 when they are available (@pxref{Separate Debug Files,,, gdb, Debugging
9975 The GNU distribution takes advantage of this by storing debugging
9976 information in the @code{lib/debug} sub-directory of a separate package
9977 output unimaginatively called @code{debug} (@pxref{Packages with
9978 Multiple Outputs}). Users can choose to install the @code{debug} output
9979 of a package when they need it. For instance, the following command
9980 installs the debugging information for the GNU C Library and for GNU
9984 guix package -i glibc:debug guile:debug
9987 GDB must then be told to look for debug files in the user's profile, by
9988 setting the @code{debug-file-directory} variable (consider setting it
9989 from the @file{~/.gdbinit} file, @pxref{Startup,,, gdb, Debugging with
9993 (gdb) set debug-file-directory ~/.guix-profile/lib/debug
9996 From there on, GDB will pick up debugging information from the
9997 @code{.debug} files under @file{~/.guix-profile/lib/debug}.
9999 In addition, you will most likely want GDB to be able to show the source
10000 code being debugged. To do that, you will have to unpack the source
10001 code of the package of interest (obtained with @code{guix build
10002 --source}, @pxref{Invoking guix build}), and to point GDB to that source
10003 directory using the @code{directory} command (@pxref{Source Path,
10004 @code{directory},, gdb, Debugging with GDB}).
10006 @c XXX: keep me up-to-date
10007 The @code{debug} output mechanism in Guix is implemented by the
10008 @code{gnu-build-system} (@pxref{Build Systems}). Currently, it is
10009 opt-in---debugging information is available only for those packages
10010 whose definition explicitly declares a @code{debug} output. This may be
10011 changed to opt-out in the future, if our build farm servers can handle
10012 the load. To check whether a package has a @code{debug} output, use
10013 @command{guix package --list-available} (@pxref{Invoking guix package}).
10016 @node Security Updates
10017 @section Security Updates
10020 As of version @value{VERSION}, the feature described in this section is
10024 @cindex security updates
10025 Occasionally, important security vulnerabilities are discovered in core
10026 software packages and must be patched. Guix follows a functional
10027 package management discipline (@pxref{Introduction}), which implies
10028 that, when a package is changed, @emph{every package that depends on it}
10029 must be rebuilt. This can significantly slow down the deployment of
10030 fixes in core packages such as libc or Bash, since basically the whole
10031 distribution would need to be rebuilt. Using pre-built binaries helps
10032 (@pxref{Substitutes}), but deployment may still take more time than
10036 To address that, Guix implements @dfn{grafts}, a mechanism that allows
10037 for fast deployment of critical updates without the costs associated
10038 with a whole-distribution rebuild. The idea is to rebuild only the
10039 package that needs to be patched, and then to ``graft'' it onto packages
10040 explicitly installed by the user and that were previously referring to
10041 the original package. The cost of grafting is typically very low, and
10042 order of magnitudes lower than a full rebuild of the dependency chain.
10044 @cindex replacements of packages, for grafts
10045 For instance, suppose a security update needs to be applied to Bash.
10046 Guix developers will provide a package definition for the ``fixed''
10047 Bash, say @var{bash-fixed}, in the usual way (@pxref{Defining
10048 Packages}). Then, the original package definition is augmented with a
10049 @code{replacement} field pointing to the package containing the bug fix:
10056 (replacement bash-fixed)))
10059 From there on, any package depending directly or indirectly on Bash that
10060 is installed will automatically be ``rewritten'' to refer to
10061 @var{bash-fixed} instead of @var{bash}. This grafting process takes
10062 time proportional to the size of the package, but expect less than a
10063 minute for an ``average'' package on a recent machine.
10065 Currently, the graft and the package it replaces (@var{bash-fixed} and
10066 @var{bash} in the example above) must have the exact same @code{name}
10067 and @code{version} fields. This restriction mostly comes from the fact
10068 that grafting works by patching files, including binary files, directly.
10069 Other restrictions may apply: for instance, when adding a graft to a
10070 package providing a shared library, the original shared library and its
10071 replacement must have the same @code{SONAME} and be binary-compatible.
10074 @node Package Modules
10075 @section Package Modules
10077 From a programming viewpoint, the package definitions of the
10078 GNU distribution are provided by Guile modules in the @code{(gnu packages
10079 @dots{})} name space@footnote{Note that packages under the @code{(gnu
10080 packages @dots{})} module name space are not necessarily ``GNU
10081 packages''. This module naming scheme follows the usual Guile module
10082 naming convention: @code{gnu} means that these modules are distributed
10083 as part of the GNU system, and @code{packages} identifies modules that
10084 define packages.} (@pxref{Modules, Guile modules,, guile, GNU Guile
10085 Reference Manual}). For instance, the @code{(gnu packages emacs)}
10086 module exports a variable named @code{emacs}, which is bound to a
10087 @code{<package>} object (@pxref{Defining Packages}).
10089 The @code{(gnu packages @dots{})} module name space is
10090 automatically scanned for packages by the command-line tools. For
10091 instance, when running @code{guix package -i emacs}, all the @code{(gnu
10092 packages @dots{})} modules are scanned until one that exports a package
10093 object whose name is @code{emacs} is found. This package search
10094 facility is implemented in the @code{(gnu packages)} module.
10096 @cindex customization, of packages
10097 @cindex package module search path
10098 Users can store package definitions in modules with different
10099 names---e.g., @code{(my-packages emacs)}@footnote{Note that the file
10100 name and module name must match. For instance, the @code{(my-packages
10101 emacs)} module must be stored in a @file{my-packages/emacs.scm} file
10102 relative to the load path specified with @option{--load-path} or
10103 @code{GUIX_PACKAGE_PATH}. @xref{Modules and the File System,,,
10104 guile, GNU Guile Reference Manual}, for details.}. These package definitions
10105 will not be visible by default. Thus, users can invoke commands such as
10106 @command{guix package} and @command{guix build} have to be used with the
10107 @code{-e} option so that they know where to find the package. Better
10108 yet, they can use the
10109 @code{-L} option of these commands to make those modules visible
10110 (@pxref{Invoking guix build, @code{--load-path}}), or define the
10111 @code{GUIX_PACKAGE_PATH} environment variable. This environment
10112 variable makes it easy to extend or customize the distribution and is
10113 honored by all the user interfaces.
10115 @defvr {Environment Variable} GUIX_PACKAGE_PATH
10116 This is a colon-separated list of directories to search for package
10117 modules. Directories listed in this variable take precedence over the
10118 distribution's own modules.
10121 The distribution is fully @dfn{bootstrapped} and @dfn{self-contained}:
10122 each package is built based solely on other packages in the
10123 distribution. The root of this dependency graph is a small set of
10124 @dfn{bootstrap binaries}, provided by the @code{(gnu packages
10125 bootstrap)} module. For more information on bootstrapping,
10126 @pxref{Bootstrapping}.
10128 @node Packaging Guidelines
10129 @section Packaging Guidelines
10131 The GNU distribution is nascent and may well lack some of your favorite
10132 packages. This section describes how you can help make the distribution
10133 grow. @xref{Contributing}, for additional information on how you can
10136 Free software packages are usually distributed in the form of
10137 @dfn{source code tarballs}---typically @file{tar.gz} files that contain
10138 all the source files. Adding a package to the distribution means
10139 essentially two things: adding a @dfn{recipe} that describes how to
10140 build the package, including a list of other packages required to build
10141 it, and adding @dfn{package meta-data} along with that recipe, such as a
10142 description and licensing information.
10144 In Guix all this information is embodied in @dfn{package definitions}.
10145 Package definitions provide a high-level view of the package. They are
10146 written using the syntax of the Scheme programming language; in fact,
10147 for each package we define a variable bound to the package definition,
10148 and export that variable from a module (@pxref{Package Modules}).
10149 However, in-depth Scheme knowledge is @emph{not} a prerequisite for
10150 creating packages. For more information on package definitions,
10151 @pxref{Defining Packages}.
10153 Once a package definition is in place, stored in a file in the Guix
10154 source tree, it can be tested using the @command{guix build} command
10155 (@pxref{Invoking guix build}). For example, assuming the new package is
10156 called @code{gnew}, you may run this command from the Guix build tree
10157 (@pxref{Running Guix Before It Is Installed}):
10160 ./pre-inst-env guix build gnew --keep-failed
10163 Using @code{--keep-failed} makes it easier to debug build failures since
10164 it provides access to the failed build tree. Another useful
10165 command-line option when debugging is @code{--log-file}, to access the
10168 If the package is unknown to the @command{guix} command, it may be that
10169 the source file contains a syntax error, or lacks a @code{define-public}
10170 clause to export the package variable. To figure it out, you may load
10171 the module from Guile to get more information about the actual error:
10174 ./pre-inst-env guile -c '(use-modules (gnu packages gnew))'
10177 Once your package builds correctly, please send us a patch
10178 (@pxref{Contributing}). Well, if you need help, we will be happy to
10179 help you too. Once the patch is committed in the Guix repository, the
10180 new package automatically gets built on the supported platforms by
10181 @url{http://hydra.gnu.org/jobset/gnu/master, our continuous integration
10184 @cindex substituter
10185 Users can obtain the new package definition simply by running
10186 @command{guix pull} (@pxref{Invoking guix pull}). When
10187 @code{hydra.gnu.org} is done building the package, installing the
10188 package automatically downloads binaries from there
10189 (@pxref{Substitutes}). The only place where human intervention is
10190 needed is to review and apply the patch.
10194 * Software Freedom:: What may go into the distribution.
10195 * Package Naming:: What's in a name?
10196 * Version Numbers:: When the name is not enough.
10197 * Synopses and Descriptions:: Helping users find the right package.
10198 * Python Modules:: Taming the snake.
10199 * Perl Modules:: Little pearls.
10200 * Fonts:: Fond of fonts.
10203 @node Software Freedom
10204 @subsection Software Freedom
10206 @c Adapted from http://www.gnu.org/philosophy/philosophy.html.
10208 The GNU operating system has been developed so that users can have
10209 freedom in their computing. GNU is @dfn{free software}, meaning that
10210 users have the @url{http://www.gnu.org/philosophy/free-sw.html,four
10211 essential freedoms}: to run the program, to study and change the program
10212 in source code form, to redistribute exact copies, and to distribute
10213 modified versions. Packages found in the GNU distribution provide only
10214 software that conveys these four freedoms.
10216 In addition, the GNU distribution follow the
10217 @url{http://www.gnu.org/distros/free-system-distribution-guidelines.html,free
10218 software distribution guidelines}. Among other things, these guidelines
10219 reject non-free firmware, recommendations of non-free software, and
10220 discuss ways to deal with trademarks and patents.
10222 Some packages contain a small and optional subset that violates the
10223 above guidelines, for instance because this subset is itself non-free
10224 code. When that happens, the offending items are removed with
10225 appropriate patches or code snippets in the package definition's
10226 @code{origin} form (@pxref{Defining Packages}). That way, @code{guix
10227 build --source} returns the ``freed'' source rather than the unmodified
10231 @node Package Naming
10232 @subsection Package Naming
10234 A package has actually two names associated with it:
10235 First, there is the name of the @emph{Scheme variable}, the one following
10236 @code{define-public}. By this name, the package can be made known in the
10237 Scheme code, for instance as input to another package. Second, there is
10238 the string in the @code{name} field of a package definition. This name
10239 is used by package management commands such as
10240 @command{guix package} and @command{guix build}.
10242 Both are usually the same and correspond to the lowercase conversion of
10243 the project name chosen upstream, with underscores replaced with
10244 hyphens. For instance, GNUnet is available as @code{gnunet}, and
10245 SDL_net as @code{sdl-net}.
10247 We do not add @code{lib} prefixes for library packages, unless these are
10248 already part of the official project name. But @pxref{Python
10249 Modules} and @ref{Perl Modules} for special rules concerning modules for
10250 the Python and Perl languages.
10252 Font package names are handled differently, @pxref{Fonts}.
10255 @node Version Numbers
10256 @subsection Version Numbers
10258 We usually package only the latest version of a given free software
10259 project. But sometimes, for instance for incompatible library versions,
10260 two (or more) versions of the same package are needed. These require
10261 different Scheme variable names. We use the name as defined
10262 in @ref{Package Naming}
10263 for the most recent version; previous versions use the same name, suffixed
10264 by @code{-} and the smallest prefix of the version number that may
10265 distinguish the two versions.
10267 The name inside the package definition is the same for all versions of a
10268 package and does not contain any version number.
10270 For instance, the versions 2.24.20 and 3.9.12 of GTK+ may be packaged as follows:
10273 (define-public gtk+
10278 (define-public gtk+-2
10281 (version "2.24.20")
10284 If we also wanted GTK+ 3.8.2, this would be packaged as
10286 (define-public gtk+-3.8
10293 @c See <https://lists.gnu.org/archive/html/guix-devel/2016-01/msg00425.html>,
10294 @c for a discussion of what follows.
10295 @cindex version number, for VCS snapshots
10296 Occasionally, we package snapshots of upstream's version control system
10297 (VCS) instead of formal releases. This should remain exceptional,
10298 because it is up to upstream developers to clarify what the stable
10299 release is. Yet, it is sometimes necessary. So, what should we put in
10300 the @code{version} field?
10302 Clearly, we need to make the commit identifier of the VCS snapshot
10303 visible in the version string, but we also need to make sure that the
10304 version string is monotonically increasing so that @command{guix package
10305 --upgrade} can determine which version is newer. Since commit
10306 identifiers, notably with Git, are not monotonically increasing, we add
10307 a revision number that we increase each time we upgrade to a newer
10308 snapshot. The resulting version string looks like this:
10313 | | `-- upstream commit ID
10315 | `--- Guix package revision
10317 latest upstream version
10320 It is a good idea to strip commit identifiers in the @code{version}
10321 field to, say, 7 digits. It avoids an aesthetic annoyance (assuming
10322 aesthetics have a role to play here) as well as problems related to OS
10323 limits such as the maximum shebang length (127 bytes for the Linux
10324 kernel.) It is best to use the full commit identifiers in
10325 @code{origin}s, though, to avoid ambiguities.
10327 @node Synopses and Descriptions
10328 @subsection Synopses and Descriptions
10330 As we have seen before, each package in GNU@tie{}Guix includes a
10331 synopsis and a description (@pxref{Defining Packages}). Synopses and
10332 descriptions are important: They are what @command{guix package
10333 --search} searches, and a crucial piece of information to help users
10334 determine whether a given package suits their needs. Consequently,
10335 packagers should pay attention to what goes into them.
10337 Synopses must start with a capital letter and must not end with a
10338 period. They must not start with ``a'' or ``the'', which usually does
10339 not bring anything; for instance, prefer ``File-frobbing tool'' over ``A
10340 tool that frobs files''. The synopsis should say what the package
10341 is---e.g., ``Core GNU utilities (file, text, shell)''---or what it is
10342 used for---e.g., the synopsis for GNU@tie{}grep is ``Print lines
10343 matching a pattern''.
10345 Keep in mind that the synopsis must be meaningful for a very wide
10346 audience. For example, ``Manipulate alignments in the SAM format''
10347 might make sense for a seasoned bioinformatics researcher, but might be
10348 fairly unhelpful or even misleading to a non-specialized audience. It
10349 is a good idea to come up with a synopsis that gives an idea of the
10350 application domain of the package. In this example, this might give
10351 something like ``Manipulate nucleotide sequence alignments'', which
10352 hopefully gives the user a better idea of whether this is what they are
10355 @cindex Texinfo markup, in package descriptions
10356 Descriptions should take between five and ten lines. Use full
10357 sentences, and avoid using acronyms without first introducing them.
10358 Descriptions can include Texinfo markup, which is useful to introduce
10359 ornaments such as @code{@@code} or @code{@@dfn}, bullet lists, or
10360 hyperlinks (@pxref{Overview,,, texinfo, GNU Texinfo}). However you
10361 should be careful when using some characters for example @samp{@@} and
10362 curly braces which are the basic special characters in Texinfo
10363 (@pxref{Special Characters,,, texinfo, GNU Texinfo}). User interfaces
10364 such as @command{guix package --show} take care of rendering it
10367 Synopses and descriptions are translated by volunteers
10368 @uref{http://translationproject.org/domain/guix-packages.html, at the
10369 Translation Project} so that as many users as possible can read them in
10370 their native language. User interfaces search them and display them in
10371 the language specified by the current locale.
10373 Translation is a lot of work so, as a packager, please pay even more
10374 attention to your synopses and descriptions as every change may entail
10375 additional work for translators. In order to help them, it is possible
10376 to make recommendations or instructions visible to them by inserting
10377 special comments like this (@pxref{xgettext Invocation,,, gettext, GNU
10381 ;; TRANSLATORS: "X11 resize-and-rotate" should not be translated.
10382 (description "ARandR is designed to provide a simple visual front end
10383 for the X11 resize-and-rotate (RandR) extension. @dots{}")
10387 @node Python Modules
10388 @subsection Python Modules
10390 We currently package Python 2 and Python 3, under the Scheme variable names
10391 @code{python-2} and @code{python} as explained in @ref{Version Numbers}.
10392 To avoid confusion and naming clashes with other programming languages, it
10393 seems desirable that the name of a package for a Python module contains
10394 the word @code{python}.
10396 Some modules are compatible with only one version of Python, others with both.
10397 If the package Foo compiles only with Python 3, we name it
10398 @code{python-foo}; if it compiles only with Python 2, we name it
10399 @code{python2-foo}. If it is compatible with both versions, we create two
10400 packages with the corresponding names.
10402 If a project already contains the word @code{python}, we drop this;
10403 for instance, the module python-dateutil is packaged under the names
10404 @code{python-dateutil} and @code{python2-dateutil}.
10408 @subsection Perl Modules
10410 Perl programs standing for themselves are named as any other package,
10411 using the lowercase upstream name.
10412 For Perl packages containing a single class, we use the lowercase class name,
10413 replace all occurrences of @code{::} by dashes and prepend the prefix
10415 So the class @code{XML::Parser} becomes @code{perl-xml-parser}.
10416 Modules containing several classes keep their lowercase upstream name and
10417 are also prepended by @code{perl-}. Such modules tend to have the word
10418 @code{perl} somewhere in their name, which gets dropped in favor of the
10419 prefix. For instance, @code{libwww-perl} becomes @code{perl-libwww}.
10425 For fonts that are in general not installed by a user for typesetting
10426 purposes, or that are distributed as part of a larger software package,
10427 we rely on the general packaging rules for software; for instance, this
10428 applies to the fonts delivered as part of the X.Org system or fonts that
10429 are part of TeX Live.
10431 To make it easier for a user to search for fonts, names for other packages
10432 containing only fonts are constructed as follows, independently of the
10433 upstream package name.
10435 The name of a package containing only one font family starts with
10436 @code{font-}; it is followed by the foundry name and a dash @code{-}
10437 if the foundry is known, and the font family name, in which spaces are
10438 replaced by dashes (and as usual, all upper case letters are transformed
10440 For example, the Gentium font family by SIL is packaged under the name
10441 @code{font-sil-gentium}.
10443 For a package containing several font families, the name of the collection
10444 is used in the place of the font family name.
10445 For instance, the Liberation fonts consist of three families,
10446 Liberation Sans, Liberation Serif and Liberation Mono.
10447 These could be packaged separately under the names
10448 @code{font-liberation-sans} and so on; but as they are distributed together
10449 under a common name, we prefer to package them together as
10450 @code{font-liberation}.
10452 In the case where several formats of the same font family or font collection
10453 are packaged separately, a short form of the format, prepended by a dash,
10454 is added to the package name. We use @code{-ttf} for TrueType fonts,
10455 @code{-otf} for OpenType fonts and @code{-type1} for PostScript Type 1
10460 @node Bootstrapping
10461 @section Bootstrapping
10463 @c Adapted from the ELS 2013 paper.
10465 @cindex bootstrapping
10467 Bootstrapping in our context refers to how the distribution gets built
10468 ``from nothing''. Remember that the build environment of a derivation
10469 contains nothing but its declared inputs (@pxref{Introduction}). So
10470 there's an obvious chicken-and-egg problem: how does the first package
10471 get built? How does the first compiler get compiled? Note that this is
10472 a question of interest only to the curious hacker, not to the regular
10473 user, so you can shamelessly skip this section if you consider yourself
10474 a ``regular user''.
10476 @cindex bootstrap binaries
10477 The GNU system is primarily made of C code, with libc at its core. The
10478 GNU build system itself assumes the availability of a Bourne shell and
10479 command-line tools provided by GNU Coreutils, Awk, Findutils, `sed', and
10480 `grep'. Furthermore, build programs---programs that run
10481 @code{./configure}, @code{make}, etc.---are written in Guile Scheme
10482 (@pxref{Derivations}). Consequently, to be able to build anything at
10483 all, from scratch, Guix relies on pre-built binaries of Guile, GCC,
10484 Binutils, libc, and the other packages mentioned above---the
10485 @dfn{bootstrap binaries}.
10487 These bootstrap binaries are ``taken for granted'', though we can also
10488 re-create them if needed (more on that later).
10490 @unnumberedsubsec Preparing to Use the Bootstrap Binaries
10492 @c As of Emacs 24.3, Info-mode displays the image, but since it's a
10493 @c large image, it's hard to scroll. Oh well.
10494 @image{images/bootstrap-graph,6in,,Dependency graph of the early bootstrap derivations}
10496 The figure above shows the very beginning of the dependency graph of the
10497 distribution, corresponding to the package definitions of the @code{(gnu
10498 packages bootstrap)} module. A similar figure can be generated with
10499 @command{guix graph} (@pxref{Invoking guix graph}), along the lines of:
10502 guix graph -t derivation \
10503 -e '(@@@@ (gnu packages bootstrap) %bootstrap-gcc)' \
10507 At this level of detail, things are
10508 slightly complex. First, Guile itself consists of an ELF executable,
10509 along with many source and compiled Scheme files that are dynamically
10510 loaded when it runs. This gets stored in the @file{guile-2.0.7.tar.xz}
10511 tarball shown in this graph. This tarball is part of Guix's ``source''
10512 distribution, and gets inserted into the store with @code{add-to-store}
10513 (@pxref{The Store}).
10515 But how do we write a derivation that unpacks this tarball and adds it
10516 to the store? To solve this problem, the @code{guile-bootstrap-2.0.drv}
10517 derivation---the first one that gets built---uses @code{bash} as its
10518 builder, which runs @code{build-bootstrap-guile.sh}, which in turn calls
10519 @code{tar} to unpack the tarball. Thus, @file{bash}, @file{tar},
10520 @file{xz}, and @file{mkdir} are statically-linked binaries, also part of
10521 the Guix source distribution, whose sole purpose is to allow the Guile
10522 tarball to be unpacked.
10524 Once @code{guile-bootstrap-2.0.drv} is built, we have a functioning
10525 Guile that can be used to run subsequent build programs. Its first task
10526 is to download tarballs containing the other pre-built binaries---this
10527 is what the @code{.tar.xz.drv} derivations do. Guix modules such as
10528 @code{ftp-client.scm} are used for this purpose. The
10529 @code{module-import.drv} derivations import those modules in a directory
10530 in the store, using the original layout. The
10531 @code{module-import-compiled.drv} derivations compile those modules, and
10532 write them in an output directory with the right layout. This
10533 corresponds to the @code{#:modules} argument of
10534 @code{build-expression->derivation} (@pxref{Derivations}).
10536 Finally, the various tarballs are unpacked by the
10537 derivations @code{gcc-bootstrap-0.drv}, @code{glibc-bootstrap-0.drv},
10538 etc., at which point we have a working C tool chain.
10541 @unnumberedsubsec Building the Build Tools
10543 Bootstrapping is complete when we have a full tool chain that does not
10544 depend on the pre-built bootstrap tools discussed above. This
10545 no-dependency requirement is verified by checking whether the files of
10546 the final tool chain contain references to the @file{/gnu/store}
10547 directories of the bootstrap inputs. The process that leads to this
10548 ``final'' tool chain is described by the package definitions found in
10549 the @code{(gnu packages commencement)} module.
10551 The @command{guix graph} command allows us to ``zoom out'' compared to
10552 the graph above, by looking at the level of package objects instead of
10553 individual derivations---remember that a package may translate to
10554 several derivations, typically one derivation to download its source,
10555 one to build the Guile modules it needs, and one to actually build the
10556 package from source. The command:
10559 guix graph -t bag \
10560 -e '(@@@@ (gnu packages commencement)
10561 glibc-final-with-bootstrap-bash)' | dot -Tps > t.ps
10565 produces the dependency graph leading to the ``final'' C
10566 library@footnote{You may notice the @code{glibc-intermediate} label,
10567 suggesting that it is not @emph{quite} final, but as a good
10568 approximation, we will consider it final.}, depicted below.
10570 @image{images/bootstrap-packages,6in,,Dependency graph of the early packages}
10572 @c See <http://lists.gnu.org/archive/html/gnu-system-discuss/2012-10/msg00000.html>.
10573 The first tool that gets built with the bootstrap binaries is
10574 GNU@tie{}Make---noted @code{make-boot0} above---which is a prerequisite
10575 for all the following packages. From there Findutils and Diffutils get
10578 Then come the first-stage Binutils and GCC, built as pseudo cross
10579 tools---i.e., with @code{--target} equal to @code{--host}. They are
10580 used to build libc. Thanks to this cross-build trick, this libc is
10581 guaranteed not to hold any reference to the initial tool chain.
10583 From there the final Binutils and GCC (not shown above) are built.
10585 from the final Binutils, and links programs against the just-built libc.
10586 This tool chain is used to build the other packages used by Guix and by
10587 the GNU Build System: Guile, Bash, Coreutils, etc.
10589 And voilà! At this point we have the complete set of build tools that
10590 the GNU Build System expects. These are in the @code{%final-inputs}
10591 variable of the @code{(gnu packages commencement)} module, and are
10592 implicitly used by any package that uses @code{gnu-build-system}
10593 (@pxref{Build Systems, @code{gnu-build-system}}).
10596 @unnumberedsubsec Building the Bootstrap Binaries
10598 Because the final tool chain does not depend on the bootstrap binaries,
10599 those rarely need to be updated. Nevertheless, it is useful to have an
10600 automated way to produce them, should an update occur, and this is what
10601 the @code{(gnu packages make-bootstrap)} module provides.
10603 The following command builds the tarballs containing the bootstrap
10604 binaries (Guile, Binutils, GCC, libc, and a tarball containing a mixture
10605 of Coreutils and other basic command-line tools):
10608 guix build bootstrap-tarballs
10611 The generated tarballs are those that should be referred to in the
10612 @code{(gnu packages bootstrap)} module mentioned at the beginning of
10615 Still here? Then perhaps by now you've started to wonder: when do we
10616 reach a fixed point? That is an interesting question! The answer is
10617 unknown, but if you would like to investigate further (and have
10618 significant computational and storage resources to do so), then let us
10622 @section Porting to a New Platform
10624 As discussed above, the GNU distribution is self-contained, and
10625 self-containment is achieved by relying on pre-built ``bootstrap
10626 binaries'' (@pxref{Bootstrapping}). These binaries are specific to an
10627 operating system kernel, CPU architecture, and application binary
10628 interface (ABI). Thus, to port the distribution to a platform that is
10629 not yet supported, one must build those bootstrap binaries, and update
10630 the @code{(gnu packages bootstrap)} module to use them on that platform.
10632 Fortunately, Guix can @emph{cross compile} those bootstrap binaries.
10633 When everything goes well, and assuming the GNU tool chain supports the
10634 target platform, this can be as simple as running a command like this
10638 guix build --target=armv5tel-linux-gnueabi bootstrap-tarballs
10641 For this to work, the @code{glibc-dynamic-linker} procedure in
10642 @code{(gnu packages bootstrap)} must be augmented to return the right
10643 file name for libc's dynamic linker on that platform; likewise,
10644 @code{system->linux-architecture} in @code{(gnu packages linux)} must be
10645 taught about the new platform.
10647 Once these are built, the @code{(gnu packages bootstrap)} module needs
10648 to be updated to refer to these binaries on the target platform. That
10649 is, the hashes and URLs of the bootstrap tarballs for the new platform
10650 must be added alongside those of the currently supported platforms. The
10651 bootstrap Guile tarball is treated specially: it is expected to be
10652 available locally, and @file{gnu-system.am} has rules do download it for
10653 the supported architectures; a rule for the new platform must be added
10656 In practice, there may be some complications. First, it may be that the
10657 extended GNU triplet that specifies an ABI (like the @code{eabi} suffix
10658 above) is not recognized by all the GNU tools. Typically, glibc
10659 recognizes some of these, whereas GCC uses an extra @code{--with-abi}
10660 configure flag (see @code{gcc.scm} for examples of how to handle this).
10661 Second, some of the required packages could fail to build for that
10662 platform. Lastly, the generated binaries could be broken for some
10665 @c *********************************************************************
10666 @include contributing.texi
10668 @c *********************************************************************
10669 @node Acknowledgments
10670 @chapter Acknowledgments
10672 Guix is based on the @uref{http://nixos.org/nix/, Nix package manager},
10673 which was designed and
10674 implemented by Eelco Dolstra, with contributions from other people (see
10675 the @file{nix/AUTHORS} file in Guix.) Nix pioneered functional package
10676 management, and promoted unprecedented features, such as transactional
10677 package upgrades and rollbacks, per-user profiles, and referentially
10678 transparent build processes. Without this work, Guix would not exist.
10680 The Nix-based software distributions, Nixpkgs and NixOS, have also been
10681 an inspiration for Guix.
10683 GNU@tie{}Guix itself is a collective work with contributions from a
10684 number of people. See the @file{AUTHORS} file in Guix for more
10685 information on these fine people. The @file{THANKS} file lists people
10686 who have helped by reporting bugs, taking care of the infrastructure,
10687 providing artwork and themes, making suggestions, and more---thank you!
10690 @c *********************************************************************
10691 @node GNU Free Documentation License
10692 @appendix GNU Free Documentation License
10694 @include fdl-1.3.texi
10696 @c *********************************************************************
10697 @node Concept Index
10698 @unnumbered Concept Index
10701 @node Programming Index
10702 @unnumbered Programming Index
10703 @syncodeindex tp fn
10704 @syncodeindex vr fn
10709 @c Local Variables:
10710 @c ispell-local-dictionary: "american";