6 @documentencoding UTF-8
7 @settitle GNU Guix Reference Manual
13 Copyright @copyright{} 2012, 2013, 2014, 2015, 2016 Ludovic Courtès@*
14 Copyright @copyright{} 2013, 2014, 2016 Andreas Enge@*
15 Copyright @copyright{} 2013 Nikita Karetnikov@*
16 Copyright @copyright{} 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
20 Copyright @copyright{} 2016 Ben Woodcroft
22 Permission is granted to copy, distribute and/or modify this document
23 under the terms of the GNU Free Documentation License, Version 1.3 or
24 any later version published by the Free Software Foundation; with no
25 Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A
26 copy of the license is included in the section entitled ``GNU Free
27 Documentation License''.
30 @dircategory Package management
32 * guix: (guix). Guix, the functional package manager.
33 * guix package: (guix)Invoking guix package
34 Managing packages with Guix.
35 * guix build: (guix)Invoking guix build
36 Building packages with Guix.
37 * guix system: (guix)Invoking guix system
38 Managing the operating system configuration.
41 @dircategory Software development
43 * guix environment: (guix)Invoking guix environment
44 Building development environments with Guix.
48 @title GNU Guix Reference Manual
49 @subtitle Using the GNU Guix Functional Package Manager
50 @author The GNU Guix Developers
53 @vskip 0pt plus 1filll
54 Edition @value{EDITION} @*
62 @c *********************************************************************
66 This document describes GNU Guix version @value{VERSION}, a functional
67 package management tool written for the GNU system.
70 * Introduction:: What is Guix about?
71 * Installation:: Installing Guix.
72 * Package Management:: Package installation, upgrade, etc.
73 * Emacs Interface:: Using Guix from Emacs.
74 * Programming Interface:: Using Guix in Scheme.
75 * Utilities:: Package management commands.
76 * GNU Distribution:: Software for your friendly GNU system.
77 * Contributing:: Your help needed!
79 * Acknowledgments:: Thanks!
80 * GNU Free Documentation License:: The license of this manual.
81 * Concept Index:: Concepts.
82 * Programming Index:: Data types, functions, and variables.
85 --- The Detailed Node Listing ---
89 * Binary Installation:: Getting Guix running in no time!
90 * Requirements:: Software needed to build and run Guix.
91 * Running the Test Suite:: Testing Guix.
92 * Setting Up the Daemon:: Preparing the build daemon's environment.
93 * Invoking guix-daemon:: Running the build daemon.
94 * Application Setup:: Application-specific setup.
98 * Build Environment Setup:: Preparing the isolated build environment.
99 * Daemon Offload Setup:: Offloading builds to remote machines.
103 * Features:: How Guix will make your life brighter.
104 * Invoking guix package:: Package installation, removal, etc.
105 * Substitutes:: Downloading pre-built binaries.
106 * Packages with Multiple Outputs:: Single source package, multiple outputs.
107 * Invoking guix gc:: Running the garbage collector.
108 * Invoking guix pull:: Fetching the latest Guix and distribution.
109 * Invoking guix archive:: Exporting and importing store files.
113 * Initial Setup: Emacs Initial Setup. Preparing @file{~/.emacs}.
114 * Package Management: Emacs Package Management. Managing packages and generations.
115 * Licenses: Emacs Licenses. Interface for licenses of Guix packages.
116 * Popup Interface: Emacs Popup Interface. Magit-like interface for guix commands.
117 * Prettify Mode: Emacs Prettify. Abbreviating @file{/gnu/store/@dots{}} file names.
118 * Build Log Mode: Emacs Build Log. Highlighting Guix build logs.
119 * Completions: Emacs Completions. Completing @command{guix} shell command.
120 * Development: Emacs Development. Tools for Guix developers.
121 * Hydra: Emacs Hydra. Interface for Guix build farm.
123 Programming Interface
125 * Defining Packages:: Defining new packages.
126 * Build Systems:: Specifying how packages are built.
127 * The Store:: Manipulating the package store.
128 * Derivations:: Low-level interface to package derivations.
129 * The Store Monad:: Purely functional interface to the store.
130 * G-Expressions:: Manipulating build expressions.
134 * package Reference:: The package data type.
135 * origin Reference:: The origin data type.
139 * Invoking guix build:: Building packages from the command line.
140 * Invoking guix edit:: Editing package definitions.
141 * Invoking guix download:: Downloading a file and printing its hash.
142 * Invoking guix hash:: Computing the cryptographic hash of a file.
143 * Invoking guix import:: Importing package definitions.
144 * Invoking guix refresh:: Updating package definitions.
145 * Invoking guix lint:: Finding errors in package definitions.
146 * Invoking guix size:: Profiling disk usage.
147 * Invoking guix graph:: Visualizing the graph of packages.
148 * Invoking guix environment:: Setting up development environments.
149 * Invoking guix publish:: Sharing substitutes.
150 * Invoking guix challenge:: Challenging substitute servers.
151 * Invoking guix container:: Process isolation.
155 * System Installation:: Installing the whole operating system.
156 * System Configuration:: Configuring the operating system.
157 * Installing Debugging Files:: Feeding the debugger.
158 * Security Updates:: Deploying security fixes quickly.
159 * Package Modules:: Packages from the programmer's viewpoint.
160 * Packaging Guidelines:: Growing the distribution.
161 * Bootstrapping:: GNU/Linux built from scratch.
162 * Porting:: Targeting another platform or kernel.
166 * Using the Configuration System:: Customizing your GNU system.
167 * operating-system Reference:: Detail of operating-system declarations.
168 * File Systems:: Configuring file system mounts.
169 * Mapped Devices:: Block device extra processing.
170 * User Accounts:: Specifying user accounts.
171 * Locales:: Language and cultural convention settings.
172 * Services:: Specifying system services.
173 * Setuid Programs:: Programs running with root privileges.
174 * X.509 Certificates:: Authenticating HTTPS servers.
175 * Name Service Switch:: Configuring libc's name service switch.
176 * Initial RAM Disk:: Linux-Libre bootstrapping.
177 * GRUB Configuration:: Configuring the boot loader.
178 * Invoking guix system:: Instantiating a system configuration.
179 * Running GuixSD in a VM:: How to run GuixSD in a virtual machine.
180 * Defining Services:: Adding new service definitions.
184 * Base Services:: Essential system services.
185 * Networking Services:: Network setup, SSH daemon, etc.
186 * X Window:: Graphical display.
187 * Desktop Services:: D-Bus and desktop services.
188 * Database Services:: SQL databases.
189 * Mail Services:: IMAP, POP3, SMTP, and all that.
190 * Web Services:: Web servers.
191 * Various Services:: Other services.
195 * Service Composition:: The model for composing services.
196 * Service Types and Services:: Types and services.
197 * Service Reference:: API reference.
198 * Shepherd Services:: A particular type of service.
202 * Software Freedom:: What may go into the distribution.
203 * Package Naming:: What's in a name?
204 * Version Numbers:: When the name is not enough.
205 * Synopses and Descriptions:: Helping users find the right package.
206 * Python Modules:: Taming the snake.
207 * Perl Modules:: Little pearls.
208 * Fonts:: Fond of fonts.
212 * Building from Git:: The latest and greatest.
213 * Running Guix Before It Is Installed:: Hacker tricks.
214 * The Perfect Setup:: The right tools.
215 * Coding Style:: Hygiene of the contributor.
216 * Submitting Patches:: Share your work.
220 * Programming Paradigm:: How to compose your elements.
221 * Modules:: Where to store your code?
222 * Data Types and Pattern Matching:: Implementing data structures.
223 * Formatting Code:: Writing conventions.
228 @c *********************************************************************
230 @chapter Introduction
232 GNU Guix@footnote{``Guix'' is pronounced like ``geeks'', or ``ɡiːks''
233 using the international phonetic alphabet (IPA).} is a functional
234 package management tool for the GNU system. Package management consists
235 of all activities that relate to building packages from sources,
236 honoring their build-time and run-time dependencies,
237 installing packages in user environments, upgrading installed packages
238 to new versions or rolling back to a previous set, removing unused
239 software packages, etc.
241 @cindex functional package management
242 The term @dfn{functional} refers to a specific package management
243 discipline pioneered by Nix (@pxref{Acknowledgments}).
244 In Guix, the package build and installation process is seen
245 as a function, in the mathematical sense. That function takes inputs,
246 such as build scripts, a compiler, and libraries, and
247 returns an installed package. As a pure function, its result depends
248 solely on its inputs---for instance, it cannot refer to software or
249 scripts that were not explicitly passed as inputs. A build function
250 always produces the same result when passed a given set of inputs. It
251 cannot alter the environment of the running system in
252 any way; for instance, it cannot create, modify, or delete files outside
253 of its build and installation directories. This is achieved by running
254 build processes in isolated environments (or @dfn{containers}), where only their
255 explicit inputs are visible.
258 The result of package build functions is @dfn{cached} in the file
259 system, in a special directory called @dfn{the store} (@pxref{The
260 Store}). Each package is installed in a directory of its own in the
261 store---by default under @file{/gnu/store}. The directory name contains
262 a hash of all the inputs used to build that package; thus, changing an
263 input yields a different directory name.
265 This approach is the foundation for the salient features of Guix: support
266 for transactional package upgrade and rollback, per-user installation, and
267 garbage collection of packages (@pxref{Features}).
269 Guix has a command-line interface, which allows users to build, install,
270 upgrade, and remove packages, as well as a Scheme programming interface.
272 @cindex Guix System Distribution
274 Last but not least, Guix is used to build a distribution of the GNU
275 system, with many GNU and non-GNU free software packages. The Guix
276 System Distribution, or GNU@tie{}GuixSD, takes advantage of the core
277 properties of Guix at the system level. With GuixSD, users
278 @emph{declare} all aspects of the operating system configuration, and
279 Guix takes care of instantiating that configuration in a reproducible,
280 stateless fashion. @xref{GNU Distribution}.
282 @c *********************************************************************
284 @chapter Installation
286 GNU Guix is available for download from its website at
287 @url{http://www.gnu.org/software/guix/}. This section describes the
288 software requirements of Guix, as well as how to install it and get
291 Note that this section is concerned with the installation of the package
292 manager, which can be done on top of a running GNU/Linux system. If,
293 instead, you want to install the complete GNU operating system,
294 @pxref{System Installation}.
297 * Binary Installation:: Getting Guix running in no time!
298 * Requirements:: Software needed to build and run Guix.
299 * Running the Test Suite:: Testing Guix.
300 * Setting Up the Daemon:: Preparing the build daemon's environment.
301 * Invoking guix-daemon:: Running the build daemon.
302 * Application Setup:: Application-specific setup.
305 @node Binary Installation
306 @section Binary Installation
308 This section describes how to install Guix on an arbitrary system from a
309 self-contained tarball providing binaries for Guix and for all its
310 dependencies. This is often quicker than installing from source, which
311 is described in the next sections. The only requirement is to have
314 Installing goes along these lines:
318 Download the binary tarball from
319 @indicateurl{ftp://alpha.gnu.org/gnu/guix/guix-binary-@value{VERSION}.@var{system}.tar.xz},
320 where @var{system} is @code{x86_64-linux} for an @code{x86_64} machine
321 already running the kernel Linux, and so on.
323 Make sure to download the associated @file{.sig} file and to verify the
324 authenticity of the tarball against it, along these lines:
327 $ wget ftp://alpha.gnu.org/gnu/guix/guix-binary-@value{VERSION}.@var{system}.tar.xz.sig
328 $ gpg --verify guix-binary-@value{VERSION}.@var{system}.tar.xz.sig
331 If that command fails because you do not have the required public key,
332 then run this command to import it:
335 $ gpg --keyserver keys.gnupg.net --recv-keys 3D9AEBB5
339 and rerun the @code{gpg --verify} command.
346 # tar --warning=no-timestamp -xf \
347 guix-binary-@value{VERSION}.@var{system}.tar.xz
348 # mv var/guix /var/ && mv gnu /
351 This creates @file{/gnu/store} (@pxref{The Store}) and @file{/var/guix}.
352 The latter contains a ready-to-use profile for @code{root} (see next
355 Do @emph{not} unpack the tarball on a working Guix system since that
356 would overwrite its own essential files.
358 The @code{--warning=no-timestamp} option makes sure GNU@tie{}tar does
359 not emit warnings about ``implausibly old time stamps'' (such
360 warnings were triggered by GNU@tie{}tar 1.26 and older; recent
362 They stem from the fact that all the
363 files in the archive have their modification time set to zero (which
364 means January 1st, 1970.) This is done on purpose to make sure the
365 archive content is independent of its creation time, thus making it
369 Make @code{root}'s profile available under @file{~/.guix-profile}:
372 # ln -sf /var/guix/profiles/per-user/root/guix-profile \
377 Create the group and user accounts for build users as explained below
378 (@pxref{Build Environment Setup}).
381 Run the daemon, and set it to automatically start on boot.
383 If your host distro uses the systemd init system, this can be achieved
387 # cp ~root/.guix-profile/lib/systemd/system/guix-daemon.service \
389 # systemctl start guix-daemon && systemctl enable guix-daemon
392 If your host distro uses the Upstart init system:
395 # cp ~root/.guix-profile/lib/upstart/system/guix-daemon.conf /etc/init/
399 Otherwise, you can still start the daemon manually with:
402 # ~root/.guix-profile/bin/guix-daemon --build-users-group=guixbuild
406 Make the @command{guix} command available to other users on the machine,
410 # mkdir -p /usr/local/bin
412 # ln -s /var/guix/profiles/per-user/root/guix-profile/bin/guix
415 It is also a good idea to make the Info version of this manual available
419 # mkdir -p /usr/local/share/info
420 # cd /usr/local/share/info
421 # for i in /var/guix/profiles/per-user/root/guix-profile/share/info/* ;
425 That way, assuming @file{/usr/local/share/info} is in the search path,
426 running @command{info guix} will open this manual (@pxref{Other Info
427 Directories,,, texinfo, GNU Texinfo}, for more details on changing the
431 To use substitutes from @code{hydra.gnu.org} (@pxref{Substitutes}),
435 # guix archive --authorize < ~root/.guix-profile/share/guix/hydra.gnu.org.pub
439 This completes root-level install of Guix. Each user will need to
440 perform additional steps to make their Guix envionment ready for use,
441 @pxref{Application Setup}.
443 You can confirm that Guix is working by installing a sample package into
447 # guix package -i hello
450 The @code{guix} package must remain available in @code{root}'s profile,
451 or it would become subject to garbage collection---in which case you
452 would find yourself badly handicapped by the lack of the @command{guix}
453 command. In other words, do not remove @code{guix} by running
454 @code{guix package -r guix}.
456 The binary installation tarball can be (re)produced and verified simply
457 by running the following command in the Guix source tree:
460 make guix-binary.@var{system}.tar.xz
465 @section Requirements
467 This section lists requirements when building Guix from source. The
468 build procedure for Guix is the same as for other GNU software, and is
469 not covered here. Please see the files @file{README} and @file{INSTALL}
470 in the Guix source tree for additional details.
472 GNU Guix depends on the following packages:
475 @item @url{http://gnu.org/software/guile/, GNU Guile}, version 2.0.7 or later;
476 @item @url{http://gnupg.org/, GNU libgcrypt};
477 @item @url{http://www.gnu.org/software/make/, GNU Make}.
480 The following dependencies are optional:
485 @url{http://savannah.nongnu.org/projects/guile-json/, Guile-JSON} will
486 allow you to use the @command{guix import pypi} command (@pxref{Invoking
487 guix import}). It is of
488 interest primarily for developers and not for casual users.
490 Installing @uref{http://gnutls.org/, GnuTLS-Guile} will
491 allow you to access @code{https} URLs with the @command{guix download}
492 command (@pxref{Invoking guix download}), the @command{guix import pypi}
493 command, and the @command{guix import cpan} command. This is primarily
494 of interest to developers. @xref{Guile Preparations, how to install the
495 GnuTLS bindings for Guile,, gnutls-guile, GnuTLS-Guile}.
498 Unless @code{--disable-daemon} was passed to @command{configure}, the
499 following packages are also needed:
502 @item @url{http://sqlite.org, SQLite 3};
503 @item @url{http://www.bzip.org, libbz2};
504 @item @url{http://gcc.gnu.org, GCC's g++}, with support for the
508 When a working installation of @url{http://nixos.org/nix/, the Nix package
509 manager} is available, you
510 can instead configure Guix with @code{--disable-daemon}. In that case,
511 Nix replaces the three dependencies above.
513 Guix is compatible with Nix, so it is possible to share the same store
514 between both. To do so, you must pass @command{configure} not only the
515 same @code{--with-store-dir} value, but also the same
516 @code{--localstatedir} value. The latter is essential because it
517 specifies where the database that stores metadata about the store is
518 located, among other things. The default values for Nix are
519 @code{--with-store-dir=/nix/store} and @code{--localstatedir=/nix/var}.
520 Note that @code{--disable-daemon} is not required if
521 your goal is to share the store with Nix.
523 @node Running the Test Suite
524 @section Running the Test Suite
526 After a successful @command{configure} and @code{make} run, it is a good
527 idea to run the test suite. It can help catch issues with the setup or
528 environment, or bugs in Guix itself---and really, reporting test
529 failures is a good way to help improve the software. To run the test
536 Test cases can run in parallel: you can use the @code{-j} option of
537 GNU@tie{}make to speed things up. The first run may take a few minutes
538 on a recent machine; subsequent runs will be faster because the store
539 that is created for test purposes will already have various things in
542 It is also possible to run a subset of the tests by defining the
543 @code{TESTS} makefile variable as in this example:
546 make check TESTS="tests/store.scm tests/cpio.scm"
549 Upon failure, please email @email{bug-guix@@gnu.org} and attach the
550 @file{test-suite.log} file. When @file{tests/@var{something}.scm}
551 fails, please also attach the @file{@var{something}.log} file available
552 in the top-level build directory. Please specify the Guix version being
553 used as well as version numbers of the dependencies
554 (@pxref{Requirements}) in your message.
556 @node Setting Up the Daemon
557 @section Setting Up the Daemon
560 Operations such as building a package or running the garbage collector
561 are all performed by a specialized process, the @dfn{build daemon}, on
562 behalf of clients. Only the daemon may access the store and its
563 associated database. Thus, any operation that manipulates the store
564 goes through the daemon. For instance, command-line tools such as
565 @command{guix package} and @command{guix build} communicate with the
566 daemon (@i{via} remote procedure calls) to instruct it what to do.
568 The following sections explain how to prepare the build daemon's
569 environment. See also @ref{Substitutes}, for information on how to allow
570 the daemon to download pre-built binaries.
573 * Build Environment Setup:: Preparing the isolated build environment.
574 * Daemon Offload Setup:: Offloading builds to remote machines.
577 @node Build Environment Setup
578 @subsection Build Environment Setup
580 In a standard multi-user setup, Guix and its daemon---the
581 @command{guix-daemon} program---are installed by the system
582 administrator; @file{/gnu/store} is owned by @code{root} and
583 @command{guix-daemon} runs as @code{root}. Unprivileged users may use
584 Guix tools to build packages or otherwise access the store, and the
585 daemon will do it on their behalf, ensuring that the store is kept in a
586 consistent state, and allowing built packages to be shared among users.
589 When @command{guix-daemon} runs as @code{root}, you may not want package
590 build processes themselves to run as @code{root} too, for obvious
591 security reasons. To avoid that, a special pool of @dfn{build users}
592 should be created for use by build processes started by the daemon.
593 These build users need not have a shell and a home directory: they will
594 just be used when the daemon drops @code{root} privileges in build
595 processes. Having several such users allows the daemon to launch
596 distinct build processes under separate UIDs, which guarantees that they
597 do not interfere with each other---an essential feature since builds are
598 regarded as pure functions (@pxref{Introduction}).
600 On a GNU/Linux system, a build user pool may be created like this (using
601 Bash syntax and the @code{shadow} commands):
603 @c See http://lists.gnu.org/archive/html/bug-guix/2013-01/msg00239.html
604 @c for why `-G' is needed.
606 # groupadd --system guixbuild
607 # for i in `seq -w 1 10`;
609 useradd -g guixbuild -G guixbuild \
610 -d /var/empty -s `which nologin` \
611 -c "Guix build user $i" --system \
617 The number of build users determines how many build jobs may run in
618 parallel, as specified by the @option{--max-jobs} option
619 (@pxref{Invoking guix-daemon, @option{--max-jobs}}). The
620 @code{guix-daemon} program may then be run as @code{root} with the
621 following command@footnote{If your machine uses the systemd init system,
622 dropping the @file{@var{prefix}/lib/systemd/system/guix-daemon.service}
623 file in @file{/etc/systemd/system} will ensure that
624 @command{guix-daemon} is automatically started. Similarly, if your
625 machine uses the Upstart init system, drop the
626 @file{@var{prefix}/lib/upstart/system/guix-daemon.conf}
627 file in @file{/etc/init}.}:
630 # guix-daemon --build-users-group=guixbuild
635 This way, the daemon starts build processes in a chroot, under one of
636 the @code{guixbuilder} users. On GNU/Linux, by default, the chroot
637 environment contains nothing but:
639 @c Keep this list in sync with libstore/build.cc! -----------------------
642 a minimal @code{/dev} directory, created mostly independently from the
643 host @code{/dev}@footnote{``Mostly'', because while the set of files
644 that appear in the chroot's @code{/dev} is fixed, most of these files
645 can only be created if the host has them.};
648 the @code{/proc} directory; it only shows the processes of the container
649 since a separate PID name space is used;
652 @file{/etc/passwd} with an entry for the current user and an entry for
656 @file{/etc/group} with an entry for the user's group;
659 @file{/etc/hosts} with an entry that maps @code{localhost} to
663 a writable @file{/tmp} directory.
666 You can influence the directory where the daemon stores build trees
667 @i{via} the @code{TMPDIR} environment variable. However, the build tree
668 within the chroot is always called @file{/tmp/guix-build-@var{name}.drv-0},
669 where @var{name} is the derivation name---e.g., @code{coreutils-8.24}.
670 This way, the value of @code{TMPDIR} does not leak inside build
671 environments, which avoids discrepancies in cases where build processes
672 capture the name of their build tree.
675 The daemon also honors the @code{http_proxy} environment variable for
676 HTTP downloads it performs, be it for fixed-output derivations
677 (@pxref{Derivations}) or for substitutes (@pxref{Substitutes}).
679 If you are installing Guix as an unprivileged user, it is still possible
680 to run @command{guix-daemon} provided you pass @code{--disable-chroot}.
681 However, build processes will not be isolated from one another, and not
682 from the rest of the system. Thus, build processes may interfere with
683 each other, and may access programs, libraries, and other files
684 available on the system---making it much harder to view them as
685 @emph{pure} functions.
688 @node Daemon Offload Setup
689 @subsection Using the Offload Facility
693 When desired, the build daemon can @dfn{offload}
694 derivation builds to other machines
695 running Guix, using the @code{offload} @dfn{build hook}. When that
696 feature is enabled, a list of user-specified build machines is read from
697 @file{/etc/guix/machines.scm}; every time a build is requested, for
698 instance via @code{guix build}, the daemon attempts to offload it to one
699 of the machines that satisfy the constraints of the derivation, in
700 particular its system type---e.g., @file{x86_64-linux}. Missing
701 prerequisites for the build are copied over SSH to the target machine,
702 which then proceeds with the build; upon success the output(s) of the
703 build are copied back to the initial machine.
705 The @file{/etc/guix/machines.scm} file typically looks like this:
709 (name "eightysix.example.org")
710 (system "x86_64-linux")
712 (speed 2.)) ; incredibly fast!
715 (name "meeps.example.org")
716 (system "mips64el-linux")
719 (string-append (getenv "HOME")
720 "/.lsh/identity-for-guix"))))
724 In the example above we specify a list of two build machines, one for
725 the @code{x86_64} architecture and one for the @code{mips64el}
728 In fact, this file is---not surprisingly!---a Scheme file that is
729 evaluated when the @code{offload} hook is started. Its return value
730 must be a list of @code{build-machine} objects. While this example
731 shows a fixed list of build machines, one could imagine, say, using
732 DNS-SD to return a list of potential build machines discovered in the
733 local network (@pxref{Introduction, Guile-Avahi,, guile-avahi, Using
734 Avahi in Guile Scheme Programs}). The @code{build-machine} data type is
737 @deftp {Data Type} build-machine
738 This data type represents build machines to which the daemon may offload
739 builds. The important fields are:
744 The host name of the remote machine.
747 The system type of the remote machine---e.g., @code{"x86_64-linux"}.
750 The user account to use when connecting to the remote machine over SSH.
751 Note that the SSH key pair must @emph{not} be passphrase-protected, to
752 allow non-interactive logins.
756 A number of optional fields may be specified:
761 Port number of SSH server on the machine (default: 22).
764 The SSH private key file to use when connecting to the machine.
766 Currently offloading uses GNU@tie{}lsh as its SSH client
767 (@pxref{Invoking lsh,,, GNU lsh Manual}). Thus, the key file here must
768 be an lsh key file. This may change in the future, though.
770 @item parallel-builds
771 The number of builds that may run in parallel on the machine (1 by
775 A ``relative speed factor''. The offload scheduler will tend to prefer
776 machines with a higher speed factor.
779 A list of strings denoting specific features supported by the machine.
780 An example is @code{"kvm"} for machines that have the KVM Linux modules
781 and corresponding hardware support. Derivations can request features by
782 name, and they will be scheduled on matching build machines.
787 The @code{guix} command must be in the search path on the build
788 machines, since offloading works by invoking the @code{guix archive} and
789 @code{guix build} commands. In addition, the Guix modules must be in
790 @code{$GUILE_LOAD_PATH} on the build machine---you can check whether
791 this is the case by running:
794 lsh build-machine guile -c "'(use-modules (guix config))'"
797 There is one last thing to do once @file{machines.scm} is in place. As
798 explained above, when offloading, files are transferred back and forth
799 between the machine stores. For this to work, you first need to
800 generate a key pair on each machine to allow the daemon to export signed
801 archives of files from the store (@pxref{Invoking guix archive}):
804 # guix archive --generate-key
808 Each build machine must authorize the key of the master machine so that
809 it accepts store items it receives from the master:
812 # guix archive --authorize < master-public-key.txt
816 Likewise, the master machine must authorize the key of each build machine.
818 All the fuss with keys is here to express pairwise mutual trust
819 relations between the master and the build machines. Concretely, when
820 the master receives files from a build machine (and @i{vice versa}), its
821 build daemon can make sure they are genuine, have not been tampered
822 with, and that they are signed by an authorized key.
825 @node Invoking guix-daemon
826 @section Invoking @command{guix-daemon}
828 The @command{guix-daemon} program implements all the functionality to
829 access the store. This includes launching build processes, running the
830 garbage collector, querying the availability of a build result, etc. It
831 is normally run as @code{root} like this:
834 # guix-daemon --build-users-group=guixbuild
838 For details on how to set it up, @pxref{Setting Up the Daemon}.
841 @cindex container, build environment
842 @cindex build environment
843 @cindex reproducible builds
844 By default, @command{guix-daemon} launches build processes under
845 different UIDs, taken from the build group specified with
846 @code{--build-users-group}. In addition, each build process is run in a
847 chroot environment that only contains the subset of the store that the
848 build process depends on, as specified by its derivation
849 (@pxref{Programming Interface, derivation}), plus a set of specific
850 system directories. By default, the latter contains @file{/dev} and
851 @file{/dev/pts}. Furthermore, on GNU/Linux, the build environment is a
852 @dfn{container}: in addition to having its own file system tree, it has
853 a separate mount name space, its own PID name space, network name space,
854 etc. This helps achieve reproducible builds (@pxref{Features}).
856 When the daemon performs a build on behalf of the user, it creates a
857 build directory under @file{/tmp} or under the directory specified by
858 its @code{TMPDIR} environment variable; this directory is shared with
859 the container for the duration of the build. Be aware that using a
860 directory other than @file{/tmp} can affect build results---for example,
861 with a longer directory name, a build process that uses Unix-domain
862 sockets might hit the name length limitation for @code{sun_path}, which
863 it would otherwise not hit.
865 The build directory is automatically deleted upon completion, unless the
866 build failed and the client specified @option{--keep-failed}
867 (@pxref{Invoking guix build, @option{--keep-failed}}).
869 The following command-line options are supported:
872 @item --build-users-group=@var{group}
873 Take users from @var{group} to run build processes (@pxref{Setting Up
874 the Daemon, build users}).
876 @item --no-substitutes
878 Do not use substitutes for build products. That is, always build things
879 locally instead of allowing downloads of pre-built binaries
880 (@pxref{Substitutes}).
882 By default substitutes are used, unless the client---such as the
883 @command{guix package} command---is explicitly invoked with
884 @code{--no-substitutes}.
886 When the daemon runs with @code{--no-substitutes}, clients can still
887 explicitly enable substitution @i{via} the @code{set-build-options}
888 remote procedure call (@pxref{The Store}).
890 @item --substitute-urls=@var{urls}
891 @anchor{daemon-substitute-urls}
892 Consider @var{urls} the default whitespace-separated list of substitute
893 source URLs. When this option is omitted, @indicateurl{http://hydra.gnu.org}
896 This means that substitutes may be downloaded from @var{urls}, as long
897 as they are signed by a trusted signature (@pxref{Substitutes}).
900 @item --no-build-hook
901 Do not use the @dfn{build hook}.
903 The build hook is a helper program that the daemon can start and to
904 which it submits build requests. This mechanism is used to offload
905 builds to other machines (@pxref{Daemon Offload Setup}).
907 @item --cache-failures
908 Cache build failures. By default, only successful builds are cached.
910 When this option is used, @command{guix gc --list-failures} can be used
911 to query the set of store items marked as failed; @command{guix gc
912 --clear-failures} removes store items from the set of cached failures.
913 @xref{Invoking guix gc}.
915 @item --cores=@var{n}
917 Use @var{n} CPU cores to build each derivation; @code{0} means as many
920 The default value is @code{0}, but it may be overridden by clients, such
921 as the @code{--cores} option of @command{guix build} (@pxref{Invoking
924 The effect is to define the @code{NIX_BUILD_CORES} environment variable
925 in the build process, which can then use it to exploit internal
926 parallelism---for instance, by running @code{make -j$NIX_BUILD_CORES}.
928 @item --max-jobs=@var{n}
930 Allow at most @var{n} build jobs in parallel. The default value is
931 @code{1}. Setting it to @code{0} means that no builds will be performed
932 locally; instead, the daemon will offload builds (@pxref{Daemon Offload
933 Setup}), or simply fail.
935 @item --rounds=@var{N}
936 Build each derivation @var{n} times in a row, and raise an error if
937 consecutive build results are not bit-for-bit identical. Note that this
938 setting can be overridden by clients such as @command{guix build}
939 (@pxref{Invoking guix build}).
942 Produce debugging output.
944 This is useful to debug daemon start-up issues, but then it may be
945 overridden by clients, for example the @code{--verbosity} option of
946 @command{guix build} (@pxref{Invoking guix build}).
948 @item --chroot-directory=@var{dir}
949 Add @var{dir} to the build chroot.
951 Doing this may change the result of build processes---for instance if
952 they use optional dependencies found in @var{dir} when it is available,
953 and not otherwise. For that reason, it is not recommended to do so.
954 Instead, make sure that each derivation declares all the inputs that it
957 @item --disable-chroot
958 Disable chroot builds.
960 Using this option is not recommended since, again, it would allow build
961 processes to gain access to undeclared dependencies. It is necessary,
962 though, when @command{guix-daemon} is running under an unprivileged user
965 @item --disable-log-compression
966 Disable compression of the build logs.
968 Unless @code{--lose-logs} is used, all the build logs are kept in the
969 @var{localstatedir}. To save space, the daemon automatically compresses
970 them with bzip2 by default. This option disables that.
972 @item --disable-deduplication
973 @cindex deduplication
974 Disable automatic file ``deduplication'' in the store.
976 By default, files added to the store are automatically ``deduplicated'':
977 if a newly added file is identical to another one found in the store,
978 the daemon makes the new file a hard link to the other file. This can
979 noticeably reduce disk usage, at the expense of slightly increased
980 input/output load at the end of a build process. This option disables
983 @item --gc-keep-outputs[=yes|no]
984 Tell whether the garbage collector (GC) must keep outputs of live
987 When set to ``yes'', the GC will keep the outputs of any live derivation
988 available in the store---the @code{.drv} files. The default is ``no'',
989 meaning that derivation outputs are kept only if they are GC roots.
991 @item --gc-keep-derivations[=yes|no]
992 Tell whether the garbage collector (GC) must keep derivations
993 corresponding to live outputs.
995 When set to ``yes'', as is the case by default, the GC keeps
996 derivations---i.e., @code{.drv} files---as long as at least one of their
997 outputs is live. This allows users to keep track of the origins of
998 items in their store. Setting it to ``no'' saves a bit of disk space.
1000 Note that when both @code{--gc-keep-derivations} and
1001 @code{--gc-keep-outputs} are used, the effect is to keep all the build
1002 prerequisites (the sources, compiler, libraries, and other build-time
1003 tools) of live objects in the store, regardless of whether these
1004 prerequisites are live. This is convenient for developers since it
1005 saves rebuilds or downloads.
1007 @item --impersonate-linux-2.6
1008 On Linux-based systems, impersonate Linux 2.6. This means that the
1009 kernel's @code{uname} system call will report 2.6 as the release number.
1011 This might be helpful to build programs that (usually wrongfully) depend
1012 on the kernel version number.
1015 Do not keep build logs. By default they are kept under
1016 @code{@var{localstatedir}/guix/log}.
1018 @item --system=@var{system}
1019 Assume @var{system} as the current system type. By default it is the
1020 architecture/kernel pair found at configure time, such as
1021 @code{x86_64-linux}.
1023 @item --listen=@var{socket}
1024 Listen for connections on @var{socket}, the file name of a Unix-domain
1025 socket. The default socket is
1026 @file{@var{localstatedir}/daemon-socket/socket}. This option is only
1027 useful in exceptional circumstances, such as if you need to run several
1028 daemons on the same machine.
1032 @node Application Setup
1033 @section Application Setup
1035 When using Guix on top of GNU/Linux distribution other than GuixSD---a
1036 so-called @dfn{foreign distro}---a few additional steps are needed to
1037 get everything in place. Here are some of them.
1041 @anchor{locales-and-locpath}
1042 @cindex locales, when not on GuixSD
1044 @vindex GUIX_LOCPATH
1045 Packages installed @i{via} Guix will not use the locale data of the
1046 host system. Instead, you must first install one of the locale packages
1047 available with Guix and then define the @code{GUIX_LOCPATH} environment
1051 $ guix package -i glibc-locales
1052 $ export GUIX_LOCPATH=$HOME/.guix-profile/lib/locale
1055 Note that the @code{glibc-locales} package contains data for all the
1056 locales supported by the GNU@tie{}libc and weighs in at around
1057 110@tie{}MiB. Alternatively, the @code{glibc-utf8-locales} is smaller but
1058 limited to a few UTF-8 locales.
1060 The @code{GUIX_LOCPATH} variable plays a role similar to @code{LOCPATH}
1061 (@pxref{Locale Names, @code{LOCPATH},, libc, The GNU C Library Reference
1062 Manual}). There are two important differences though:
1066 @code{GUIX_LOCPATH} is honored only by the libc in Guix, and not by the libc
1067 provided by foreign distros. Thus, using @code{GUIX_LOCPATH} allows you
1068 to make sure the programs of the foreign distro will not end up loading
1069 incompatible locale data.
1072 libc suffixes each entry of @code{GUIX_LOCPATH} with @code{/X.Y}, where
1073 @code{X.Y} is the libc version---e.g., @code{2.22}. This means that,
1074 should your Guix profile contain a mixture of programs linked against
1075 different libc version, each libc version will only try to load locale
1076 data in the right format.
1079 This is important because the locale data format used by different libc
1080 versions may be incompatible.
1082 @subsection X11 Fonts
1084 The majority of graphical applications use Fontconfig to locate and
1085 load fonts and perform X11-client-side rendering. The @code{fontconfig}
1086 package in Guix looks for fonts in @file{$HOME/.guix-profile}
1087 by default. Thus, to allow graphical applications installed with Guix
1088 to display fonts, you have to install fonts with Guix as well.
1089 Essential font packages include @code{gs-fonts}, @code{font-dejavu}, and
1090 @code{font-gnu-freefont-ttf}.
1092 To display text written in Chinese languages, Japanese, or Korean in
1093 graphical applications, consider installing
1094 @code{font-adobe-source-han-sans} or @code{font-wqy-zenhei}. The former
1095 has multiple outputs, one per language family (@pxref{Packages with
1096 Multiple Outputs}). For instance, the following command installs fonts
1097 for Chinese languages:
1100 guix package -i font-adobe-source-han-sans:cn
1103 @subsection Emacs Packages
1105 When you install Emacs packages with Guix, the elisp files may be placed
1106 either in @file{$HOME/.guix-profile/share/emacs/site-lisp/} or in
1108 @file{$HOME/.guix-profile/share/emacs/site-lisp/guix.d/}. The latter
1109 directory exists because potentially there may exist thousands of Emacs
1110 packages and storing all their files in a single directory may be not
1111 reliable (because of name conflicts). So we think using a separate
1112 directory for each package is a good idea. It is very similar to how
1113 the Emacs package system organizes the file structure (@pxref{Package
1114 Files,,, emacs, The GNU Emacs Manual}).
1116 By default, Emacs (installed with Guix) ``knows'' where these packages
1117 are placed, so you do not need to perform any configuration. If, for
1118 some reason, you want to avoid auto-loading Emacs packages installed
1119 with Guix, you can do so by running Emacs with @code{--no-site-file}
1120 option (@pxref{Init File,,, emacs, The GNU Emacs Manual}).
1124 @c *********************************************************************
1125 @node Package Management
1126 @chapter Package Management
1128 The purpose of GNU Guix is to allow users to easily install, upgrade, and
1129 remove software packages, without having to know about their build
1130 procedures or dependencies. Guix also goes beyond this obvious set of
1133 This chapter describes the main features of Guix, as well as the package
1134 management tools it provides. Two user interfaces are provided for
1135 routine package management tasks: A command-line interface described below
1136 (@pxref{Invoking guix package, @code{guix package}}), as well as a visual user
1137 interface in Emacs described in a subsequent chapter (@pxref{Emacs Interface}).
1140 * Features:: How Guix will make your life brighter.
1141 * Invoking guix package:: Package installation, removal, etc.
1142 * Substitutes:: Downloading pre-built binaries.
1143 * Packages with Multiple Outputs:: Single source package, multiple outputs.
1144 * Invoking guix gc:: Running the garbage collector.
1145 * Invoking guix pull:: Fetching the latest Guix and distribution.
1146 * Invoking guix archive:: Exporting and importing store files.
1152 When using Guix, each package ends up in the @dfn{package store}, in its
1153 own directory---something that resembles
1154 @file{/gnu/store/xxx-package-1.2}, where @code{xxx} is a base32 string
1155 (note that Guix comes with an Emacs extension to shorten those file
1156 names, @pxref{Emacs Prettify}.)
1158 Instead of referring to these directories, users have their own
1159 @dfn{profile}, which points to the packages that they actually want to
1160 use. These profiles are stored within each user's home directory, at
1161 @code{$HOME/.guix-profile}.
1163 For example, @code{alice} installs GCC 4.7.2. As a result,
1164 @file{/home/alice/.guix-profile/bin/gcc} points to
1165 @file{/gnu/store/@dots{}-gcc-4.7.2/bin/gcc}. Now, on the same machine,
1166 @code{bob} had already installed GCC 4.8.0. The profile of @code{bob}
1167 simply continues to point to
1168 @file{/gnu/store/@dots{}-gcc-4.8.0/bin/gcc}---i.e., both versions of GCC
1169 coexist on the same system without any interference.
1171 The @command{guix package} command is the central tool to manage
1172 packages (@pxref{Invoking guix package}). It operates on the per-user
1173 profiles, and can be used @emph{with normal user privileges}.
1175 The command provides the obvious install, remove, and upgrade
1176 operations. Each invocation is actually a @emph{transaction}: either
1177 the specified operation succeeds, or nothing happens. Thus, if the
1178 @command{guix package} process is terminated during the transaction,
1179 or if a power outage occurs during the transaction, then the user's
1180 profile remains in its previous state, and remains usable.
1182 In addition, any package transaction may be @emph{rolled back}. So, if,
1183 for example, an upgrade installs a new version of a package that turns
1184 out to have a serious bug, users may roll back to the previous instance
1185 of their profile, which was known to work well. Similarly, the global
1186 system configuration is subject to transactional upgrades and roll-back
1187 (@pxref{Using the Configuration System}).
1189 All packages in the package store may be @emph{garbage-collected}.
1190 Guix can determine which packages are still referenced by user
1191 profiles, and remove those that are provably no longer referenced
1192 (@pxref{Invoking guix gc}). Users may also explicitly remove old
1193 generations of their profile so that the packages they refer to can be
1196 @cindex reproducibility
1197 @cindex reproducible builds
1198 Finally, Guix takes a @dfn{purely functional} approach to package
1199 management, as described in the introduction (@pxref{Introduction}).
1200 Each @file{/gnu/store} package directory name contains a hash of all the
1201 inputs that were used to build that package---compiler, libraries, build
1202 scripts, etc. This direct correspondence allows users to make sure a
1203 given package installation matches the current state of their
1204 distribution. It also helps maximize @dfn{build reproducibility}:
1205 thanks to the isolated build environments that are used, a given build
1206 is likely to yield bit-identical files when performed on different
1207 machines (@pxref{Invoking guix-daemon, container}).
1210 This foundation allows Guix to support @dfn{transparent binary/source
1211 deployment}. When a pre-built binary for a @file{/gnu/store} item is
1212 available from an external source---a @dfn{substitute}, Guix just
1213 downloads it and unpacks it;
1214 otherwise, it builds the package from source, locally
1215 (@pxref{Substitutes}).
1217 Control over the build environment is a feature that is also useful for
1218 developers. The @command{guix environment} command allows developers of
1219 a package to quickly set up the right development environment for their
1220 package, without having to manually install the dependencies of the
1221 package into their profile (@pxref{Invoking guix environment}).
1223 @node Invoking guix package
1224 @section Invoking @command{guix package}
1226 The @command{guix package} command is the tool that allows users to
1227 install, upgrade, and remove packages, as well as rolling back to
1228 previous configurations. It operates only on the user's own profile,
1229 and works with normal user privileges (@pxref{Features}). Its syntax
1233 guix package @var{options}
1236 Primarily, @var{options} specifies the operations to be performed during
1237 the transaction. Upon completion, a new profile is created, but
1238 previous @dfn{generations} of the profile remain available, should the user
1241 For example, to remove @code{lua} and install @code{guile} and
1242 @code{guile-cairo} in a single transaction:
1245 guix package -r lua -i guile guile-cairo
1248 @command{guix package} also supports a @dfn{declarative approach}
1249 whereby the user specifies the exact set of packages to be available and
1250 passes it @i{via} the @option{--manifest} option
1251 (@pxref{profile-manifest, @option{--manifest}}).
1253 For each user, a symlink to the user's default profile is automatically
1254 created in @file{$HOME/.guix-profile}. This symlink always points to the
1255 current generation of the user's default profile. Thus, users can add
1256 @file{$HOME/.guix-profile/bin} to their @code{PATH} environment
1257 variable, and so on.
1258 @cindex search paths
1259 If you are not using the Guix System Distribution, consider adding the
1260 following lines to your @file{~/.bash_profile} (@pxref{Bash Startup
1261 Files,,, bash, The GNU Bash Reference Manual}) so that newly-spawned
1262 shells get all the right environment variable definitions:
1265 GUIX_PROFILE="$HOME/.guix-profile" \
1266 source "$HOME/.guix-profile/etc/profile"
1269 In a multi-user setup, user profiles are stored in a place registered as
1270 a @dfn{garbage-collector root}, which @file{$HOME/.guix-profile} points
1271 to (@pxref{Invoking guix gc}). That directory is normally
1272 @code{@var{localstatedir}/profiles/per-user/@var{user}}, where
1273 @var{localstatedir} is the value passed to @code{configure} as
1274 @code{--localstatedir}, and @var{user} is the user name. The
1275 @file{per-user} directory is created when @command{guix-daemon} is
1276 started, and the @var{user} sub-directory is created by @command{guix
1279 The @var{options} can be among the following:
1283 @item --install=@var{package} @dots{}
1284 @itemx -i @var{package} @dots{}
1285 Install the specified @var{package}s.
1287 Each @var{package} may specify either a simple package name, such as
1288 @code{guile}, or a package name followed by a hyphen and version number,
1289 such as @code{guile-1.8.8} or simply @code{guile-1.8} (in the latter
1290 case, the newest version prefixed by @code{1.8} is selected.)
1292 If no version number is specified, the
1293 newest available version will be selected. In addition, @var{package}
1294 may contain a colon, followed by the name of one of the outputs of the
1295 package, as in @code{gcc:doc} or @code{binutils-2.22:lib}
1296 (@pxref{Packages with Multiple Outputs}). Packages with a corresponding
1297 name (and optionally version) are searched for among the GNU
1298 distribution modules (@pxref{Package Modules}).
1300 @cindex propagated inputs
1301 Sometimes packages have @dfn{propagated inputs}: these are dependencies
1302 that automatically get installed along with the required package
1303 (@pxref{package-propagated-inputs, @code{propagated-inputs} in
1304 @code{package} objects}, for information about propagated inputs in
1305 package definitions).
1307 @anchor{package-cmd-propagated-inputs}
1308 An example is the GNU MPC library: its C header files refer to those of
1309 the GNU MPFR library, which in turn refer to those of the GMP library.
1310 Thus, when installing MPC, the MPFR and GMP libraries also get installed
1311 in the profile; removing MPC also removes MPFR and GMP---unless they had
1312 also been explicitly installed by the user.
1314 Besides, packages sometimes rely on the definition of environment
1315 variables for their search paths (see explanation of
1316 @code{--search-paths} below). Any missing or possibly incorrect
1317 environment variable definitions are reported here.
1319 @c XXX: keep me up-to-date
1320 Finally, when installing a GNU package, the tool reports the
1321 availability of a newer upstream version. In the future, it may provide
1322 the option of installing directly from the upstream version, even if
1323 that version is not yet in the distribution.
1325 @item --install-from-expression=@var{exp}
1327 Install the package @var{exp} evaluates to.
1329 @var{exp} must be a Scheme expression that evaluates to a
1330 @code{<package>} object. This option is notably useful to disambiguate
1331 between same-named variants of a package, with expressions such as
1332 @code{(@@ (gnu packages base) guile-final)}.
1334 Note that this option installs the first output of the specified
1335 package, which may be insufficient when needing a specific output of a
1336 multiple-output package.
1338 @item --install-from-file=@var{file}
1339 @itemx -f @var{file}
1340 Install the package that the code within @var{file} evaluates to.
1342 As an example, @var{file} might contain a definition like this
1343 (@pxref{Defining Packages}):
1346 @verbatiminclude package-hello.scm
1349 Developers may find it useful to include such a @file{package.scm} file
1350 in the root of their project source tree that can be used to test
1351 development snapshots and create reproducible development environments
1352 (@pxref{Invoking guix environment}).
1354 @item --remove=@var{package} @dots{}
1355 @itemx -r @var{package} @dots{}
1356 Remove the specified @var{package}s.
1358 As for @code{--install}, each @var{package} may specify a version number
1359 and/or output name in addition to the package name. For instance,
1360 @code{-r glibc:debug} would remove the @code{debug} output of
1363 @item --upgrade[=@var{regexp} @dots{}]
1364 @itemx -u [@var{regexp} @dots{}]
1365 Upgrade all the installed packages. If one or more @var{regexp}s are
1366 specified, upgrade only installed packages whose name matches a
1367 @var{regexp}. Also see the @code{--do-not-upgrade} option below.
1369 Note that this upgrades package to the latest version of packages found
1370 in the distribution currently installed. To update your distribution,
1371 you should regularly run @command{guix pull} (@pxref{Invoking guix
1374 @item --do-not-upgrade[=@var{regexp} @dots{}]
1375 When used together with the @code{--upgrade} option, do @emph{not}
1376 upgrade any packages whose name matches a @var{regexp}. For example, to
1377 upgrade all packages in the current profile except those containing the
1378 substring ``emacs'':
1381 $ guix package --upgrade . --do-not-upgrade emacs
1384 @item @anchor{profile-manifest}--manifest=@var{file}
1385 @itemx -m @var{file}
1386 @cindex profile declaration
1387 @cindex profile manifest
1388 Create a new generation of the profile from the manifest object
1389 returned by the Scheme code in @var{file}.
1391 This allows you to @emph{declare} the profile's contents rather than
1392 constructing it through a sequence of @code{--install} and similar
1393 commands. The advantage is that @var{file} can be put under version
1394 control, copied to different machines to reproduce the same profile, and
1397 @c FIXME: Add reference to (guix profile) documentation when available.
1398 @var{file} must return a @dfn{manifest} object, which is roughly a list
1401 @findex packages->manifest
1403 (use-package-modules guile emacs)
1408 ;; Use a specific package output.
1409 (list guile-2.0 "debug")))
1413 Roll back to the previous @dfn{generation} of the profile---i.e., undo
1414 the last transaction.
1416 When combined with options such as @code{--install}, roll back occurs
1417 before any other actions.
1419 When rolling back from the first generation that actually contains
1420 installed packages, the profile is made to point to the @dfn{zeroth
1421 generation}, which contains no files apart from its own metadata.
1423 After having rolled back, installing, removing, or upgrading packages
1424 overwrites previous future generations. Thus, the history of the
1425 generations in a profile is always linear.
1427 @item --switch-generation=@var{pattern}
1428 @itemx -S @var{pattern}
1429 Switch to a particular generation defined by @var{pattern}.
1431 @var{pattern} may be either a generation number or a number prefixed
1432 with ``+'' or ``-''. The latter means: move forward/backward by a
1433 specified number of generations. For example, if you want to return to
1434 the latest generation after @code{--roll-back}, use
1435 @code{--switch-generation=+1}.
1437 The difference between @code{--roll-back} and
1438 @code{--switch-generation=-1} is that @code{--switch-generation} will
1439 not make a zeroth generation, so if a specified generation does not
1440 exist, the current generation will not be changed.
1442 @item --search-paths[=@var{kind}]
1443 @cindex search paths
1444 Report environment variable definitions, in Bash syntax, that may be
1445 needed in order to use the set of installed packages. These environment
1446 variables are used to specify @dfn{search paths} for files used by some
1447 of the installed packages.
1449 For example, GCC needs the @code{CPATH} and @code{LIBRARY_PATH}
1450 environment variables to be defined so it can look for headers and
1451 libraries in the user's profile (@pxref{Environment Variables,,, gcc,
1452 Using the GNU Compiler Collection (GCC)}). If GCC and, say, the C
1453 library are installed in the profile, then @code{--search-paths} will
1454 suggest setting these variables to @code{@var{profile}/include} and
1455 @code{@var{profile}/lib}, respectively.
1457 The typical use case is to define these environment variables in the
1461 $ eval `guix package --search-paths`
1464 @var{kind} may be one of @code{exact}, @code{prefix}, or @code{suffix},
1465 meaning that the returned environment variable definitions will either
1466 be exact settings, or prefixes or suffixes of the current value of these
1467 variables. When omitted, @var{kind} defaults to @code{exact}.
1469 This option can also be used to compute the @emph{combined} search paths
1470 of several profiles. Consider this example:
1473 $ guix package -p foo -i guile
1474 $ guix package -p bar -i guile-json
1475 $ guix package -p foo -p bar --search-paths
1478 The last command above reports about the @code{GUILE_LOAD_PATH}
1479 variable, even though, taken individually, neither @file{foo} nor
1480 @file{bar} would lead to that recommendation.
1483 @item --profile=@var{profile}
1484 @itemx -p @var{profile}
1485 Use @var{profile} instead of the user's default profile.
1488 Produce verbose output. In particular, emit the build log of the
1489 environment on the standard error port.
1492 Use the bootstrap Guile to build the profile. This option is only
1493 useful to distribution developers.
1497 In addition to these actions, @command{guix package} supports the
1498 following options to query the current state of a profile, or the
1499 availability of packages:
1503 @item --search=@var{regexp}
1504 @itemx -s @var{regexp}
1505 @cindex searching for packages
1506 List the available packages whose name, synopsis, or description matches
1507 @var{regexp}. Print all the metadata of matching packages in
1508 @code{recutils} format (@pxref{Top, GNU recutils databases,, recutils,
1509 GNU recutils manual}).
1511 This allows specific fields to be extracted using the @command{recsel}
1512 command, for instance:
1515 $ guix package -s malloc | recsel -p name,version
1523 Similarly, to show the name of all the packages available under the
1524 terms of the GNU@tie{}LGPL version 3:
1527 $ guix package -s "" | recsel -p name -e 'license ~ "LGPL 3"'
1534 It is also possible to refine search results using several @code{-s}
1535 flags. For example, the following command returns a list of board
1539 $ guix package -s '\<board\>' -s game | recsel -p name
1544 If we were to omit @code{-s game}, we would also get software packages
1545 that deal with printed circuit boards; removing the angle brackets
1546 around @code{board} would further add packages that have to do with
1549 And now for a more elaborate example. The following command searches
1550 for cryptographic libraries, filters out Haskell, Perl, Python, and Ruby
1551 libraries, and prints the name and synopsis of the matching packages:
1554 $ guix package -s crypto -s library | \
1555 recsel -e '! (name ~ "^(ghc|perl|python|ruby)")' -p name,synopsis
1559 @xref{Selection Expressions,,, recutils, GNU recutils manual}, for more
1560 information on @dfn{selection expressions} for @code{recsel -e}.
1562 @item --show=@var{package}
1563 Show details about @var{package}, taken from the list of available packages, in
1564 @code{recutils} format (@pxref{Top, GNU recutils databases,, recutils, GNU
1568 $ guix package --show=python | recsel -p name,version
1576 You may also specify the full name of a package to only get details about a
1577 specific version of it:
1579 $ guix package --show=python-3.3.5 | recsel -p name,version
1586 @item --list-installed[=@var{regexp}]
1587 @itemx -I [@var{regexp}]
1588 List the currently installed packages in the specified profile, with the
1589 most recently installed packages shown last. When @var{regexp} is
1590 specified, list only installed packages whose name matches @var{regexp}.
1592 For each installed package, print the following items, separated by
1593 tabs: the package name, its version string, the part of the package that
1594 is installed (for instance, @code{out} for the default output,
1595 @code{include} for its headers, etc.), and the path of this package in
1598 @item --list-available[=@var{regexp}]
1599 @itemx -A [@var{regexp}]
1600 List packages currently available in the distribution for this system
1601 (@pxref{GNU Distribution}). When @var{regexp} is specified, list only
1602 installed packages whose name matches @var{regexp}.
1604 For each package, print the following items separated by tabs: its name,
1605 its version string, the parts of the package (@pxref{Packages with
1606 Multiple Outputs}), and the source location of its definition.
1608 @item --list-generations[=@var{pattern}]
1609 @itemx -l [@var{pattern}]
1610 Return a list of generations along with their creation dates; for each
1611 generation, show the installed packages, with the most recently
1612 installed packages shown last. Note that the zeroth generation is never
1615 For each installed package, print the following items, separated by
1616 tabs: the name of a package, its version string, the part of the package
1617 that is installed (@pxref{Packages with Multiple Outputs}), and the
1618 location of this package in the store.
1620 When @var{pattern} is used, the command returns only matching
1621 generations. Valid patterns include:
1624 @item @emph{Integers and comma-separated integers}. Both patterns denote
1625 generation numbers. For instance, @code{--list-generations=1} returns
1628 And @code{--list-generations=1,8,2} outputs three generations in the
1629 specified order. Neither spaces nor trailing commas are allowed.
1631 @item @emph{Ranges}. @code{--list-generations=2..9} prints the
1632 specified generations and everything in between. Note that the start of
1633 a range must be smaller than its end.
1635 It is also possible to omit the endpoint. For example,
1636 @code{--list-generations=2..}, returns all generations starting from the
1639 @item @emph{Durations}. You can also get the last @emph{N}@tie{}days, weeks,
1640 or months by passing an integer along with the first letter of the
1641 duration. For example, @code{--list-generations=20d} lists generations
1642 that are up to 20 days old.
1645 @item --delete-generations[=@var{pattern}]
1646 @itemx -d [@var{pattern}]
1647 When @var{pattern} is omitted, delete all generations except the current
1650 This command accepts the same patterns as @option{--list-generations}.
1651 When @var{pattern} is specified, delete the matching generations. When
1652 @var{pattern} specifies a duration, generations @emph{older} than the
1653 specified duration match. For instance, @code{--delete-generations=1m}
1654 deletes generations that are more than one month old.
1656 If the current generation matches, it is @emph{not} deleted. Also, the
1657 zeroth generation is never deleted.
1659 Note that deleting generations prevents rolling back to them.
1660 Consequently, this command must be used with care.
1664 Finally, since @command{guix package} may actually start build
1665 processes, it supports all the common build options (@pxref{Common Build
1666 Options}). It also supports package transformation options, such as
1667 @option{--with-source} (@pxref{Package Transformation Options}).
1668 However, note that package transformations are lost when upgrading; to
1669 preserve transformations across upgrades, you should define your own
1670 package variant in a Guile module and add it to @code{GUIX_PACKAGE_PATH}
1671 (@pxref{Defining Packages}).
1675 @section Substitutes
1678 @cindex pre-built binaries
1679 Guix supports transparent source/binary deployment, which means that it
1680 can either build things locally, or download pre-built items from a
1681 server. We call these pre-built items @dfn{substitutes}---they are
1682 substitutes for local build results. In many cases, downloading a
1683 substitute is much faster than building things locally.
1685 Substitutes can be anything resulting from a derivation build
1686 (@pxref{Derivations}). Of course, in the common case, they are
1687 pre-built package binaries, but source tarballs, for instance, which
1688 also result from derivation builds, can be available as substitutes.
1690 The @code{hydra.gnu.org} server is a front-end to a build farm that
1691 builds packages from the GNU distribution continuously for some
1692 architectures, and makes them available as substitutes (@pxref{Emacs
1693 Hydra}, for information on how to query the continuous integration
1694 server). This is the
1695 default source of substitutes; it can be overridden by passing the
1696 @option{--substitute-urls} option either to @command{guix-daemon}
1697 (@pxref{daemon-substitute-urls,, @code{guix-daemon --substitute-urls}})
1698 or to client tools such as @command{guix package}
1699 (@pxref{client-substitute-urls,, client @option{--substitute-urls}
1703 @cindex digital signatures
1704 To allow Guix to download substitutes from @code{hydra.gnu.org}, you
1705 must add its public key to the access control list (ACL) of archive
1706 imports, using the @command{guix archive} command (@pxref{Invoking guix
1707 archive}). Doing so implies that you trust @code{hydra.gnu.org} to not
1708 be compromised and to serve genuine substitutes.
1710 This public key is installed along with Guix, in
1711 @code{@var{prefix}/share/guix/hydra.gnu.org.pub}, where @var{prefix} is
1712 the installation prefix of Guix. If you installed Guix from source,
1713 make sure you checked the GPG signature of
1714 @file{guix-@value{VERSION}.tar.gz}, which contains this public key file.
1715 Then, you can run something like this:
1718 # guix archive --authorize < hydra.gnu.org.pub
1721 Once this is in place, the output of a command like @code{guix build}
1722 should change from something like:
1725 $ guix build emacs --dry-run
1726 The following derivations would be built:
1727 /gnu/store/yr7bnx8xwcayd6j95r2clmkdl1qh688w-emacs-24.3.drv
1728 /gnu/store/x8qsh1hlhgjx6cwsjyvybnfv2i37z23w-dbus-1.6.4.tar.gz.drv
1729 /gnu/store/1ixwp12fl950d15h2cj11c73733jay0z-alsa-lib-1.0.27.1.tar.bz2.drv
1730 /gnu/store/nlma1pw0p603fpfiqy7kn4zm105r5dmw-util-linux-2.21.drv
1738 $ guix build emacs --dry-run
1739 The following files would be downloaded:
1740 /gnu/store/pk3n22lbq6ydamyymqkkz7i69wiwjiwi-emacs-24.3
1741 /gnu/store/2ygn4ncnhrpr61rssa6z0d9x22si0va3-libjpeg-8d
1742 /gnu/store/71yz6lgx4dazma9dwn2mcjxaah9w77jq-cairo-1.12.16
1743 /gnu/store/7zdhgp0n1518lvfn8mb96sxqfmvqrl7v-libxrender-0.9.7
1748 This indicates that substitutes from @code{hydra.gnu.org} are usable and
1749 will be downloaded, when possible, for future builds.
1751 Guix ignores substitutes that are not signed, or that are not signed by
1752 one of the keys listed in the ACL. It also detects and raises an error
1753 when attempting to use a substitute that has been tampered with.
1756 Substitutes are downloaded over HTTP. The @code{http_proxy} environment
1757 variable can be set in the environment of @command{guix-daemon} and is
1758 honored for downloads of substitutes. Note that the value of
1759 @code{http_proxy} in the environment where @command{guix build},
1760 @command{guix package}, and other client commands are run has
1761 @emph{absolutely no effect}.
1763 The substitute mechanism can be disabled globally by running
1764 @code{guix-daemon} with @code{--no-substitutes} (@pxref{Invoking
1765 guix-daemon}). It can also be disabled temporarily by passing the
1766 @code{--no-substitutes} option to @command{guix package}, @command{guix
1767 build}, and other command-line tools.
1770 Today, each individual's control over their own computing is at the
1771 mercy of institutions, corporations, and groups with enough power and
1772 determination to subvert the computing infrastructure and exploit its
1773 weaknesses. While using @code{hydra.gnu.org} substitutes can be
1774 convenient, we encourage users to also build on their own, or even run
1775 their own build farm, such that @code{hydra.gnu.org} is less of an
1776 interesting target. One way to help is by publishing the software you
1777 build using @command{guix publish} so that others have one more choice
1778 of server to download substitutes from (@pxref{Invoking guix publish}).
1780 Guix has the foundations to maximize build reproducibility
1781 (@pxref{Features}). In most cases, independent builds of a given
1782 package or derivation should yield bit-identical results. Thus, through
1783 a diverse set of independent package builds, we can strengthen the
1784 integrity of our systems. The @command{guix challenge} command aims to
1785 help users assess substitute servers, and to assist developers in
1786 finding out about non-deterministic package builds (@pxref{Invoking guix
1787 challenge}). Similarly, the @option{--check} option of @command{guix
1788 build} allows users to check whether previously-installed substitutes
1789 are genuine by rebuilding them locally (@pxref{build-check,
1790 @command{guix build --check}}).
1792 In the future, we want Guix to have support to publish and retrieve
1793 binaries to/from other users, in a peer-to-peer fashion. If you would
1794 like to discuss this project, join us on @email{guix-devel@@gnu.org}.
1797 @node Packages with Multiple Outputs
1798 @section Packages with Multiple Outputs
1800 @cindex multiple-output packages
1801 @cindex package outputs
1803 Often, packages defined in Guix have a single @dfn{output}---i.e., the
1804 source package leads to exactly one directory in the store. When running
1805 @command{guix package -i glibc}, one installs the default output of the
1806 GNU libc package; the default output is called @code{out}, but its name
1807 can be omitted as shown in this command. In this particular case, the
1808 default output of @code{glibc} contains all the C header files, shared
1809 libraries, static libraries, Info documentation, and other supporting
1812 Sometimes it is more appropriate to separate the various types of files
1813 produced from a single source package into separate outputs. For
1814 instance, the GLib C library (used by GTK+ and related packages)
1815 installs more than 20 MiB of reference documentation as HTML pages.
1816 To save space for users who do not need it, the documentation goes to a
1817 separate output, called @code{doc}. To install the main GLib output,
1818 which contains everything but the documentation, one would run:
1821 guix package -i glib
1824 The command to install its documentation is:
1827 guix package -i glib:doc
1830 Some packages install programs with different ``dependency footprints''.
1831 For instance, the WordNet package installs both command-line tools and
1832 graphical user interfaces (GUIs). The former depend solely on the C
1833 library, whereas the latter depend on Tcl/Tk and the underlying X
1834 libraries. In this case, we leave the command-line tools in the default
1835 output, whereas the GUIs are in a separate output. This allows users
1836 who do not need the GUIs to save space. The @command{guix size} command
1837 can help find out about such situations (@pxref{Invoking guix size}).
1838 @command{guix graph} can also be helpful (@pxref{Invoking guix graph}).
1840 There are several such multiple-output packages in the GNU distribution.
1841 Other conventional output names include @code{lib} for libraries and
1842 possibly header files, @code{bin} for stand-alone programs, and
1843 @code{debug} for debugging information (@pxref{Installing Debugging
1844 Files}). The outputs of a packages are listed in the third column of
1845 the output of @command{guix package --list-available} (@pxref{Invoking
1849 @node Invoking guix gc
1850 @section Invoking @command{guix gc}
1852 @cindex garbage collector
1853 Packages that are installed, but not used, may be @dfn{garbage-collected}.
1854 The @command{guix gc} command allows users to explicitly run the garbage
1855 collector to reclaim space from the @file{/gnu/store} directory. It is
1856 the @emph{only} way to remove files from @file{/gnu/store}---removing
1857 files or directories manually may break it beyond repair!
1859 The garbage collector has a set of known @dfn{roots}: any file under
1860 @file{/gnu/store} reachable from a root is considered @dfn{live} and
1861 cannot be deleted; any other file is considered @dfn{dead} and may be
1862 deleted. The set of garbage collector roots includes default user
1863 profiles, and may be augmented with @command{guix build --root}, for
1864 example (@pxref{Invoking guix build}).
1866 Prior to running @code{guix gc --collect-garbage} to make space, it is
1867 often useful to remove old generations from user profiles; that way, old
1868 package builds referenced by those generations can be reclaimed. This
1869 is achieved by running @code{guix package --delete-generations}
1870 (@pxref{Invoking guix package}).
1872 The @command{guix gc} command has three modes of operation: it can be
1873 used to garbage-collect any dead files (the default), to delete specific
1874 files (the @code{--delete} option), to print garbage-collector
1875 information, or for more advanced queries. The garbage collection
1876 options are as follows:
1879 @item --collect-garbage[=@var{min}]
1880 @itemx -C [@var{min}]
1881 Collect garbage---i.e., unreachable @file{/gnu/store} files and
1882 sub-directories. This is the default operation when no option is
1885 When @var{min} is given, stop once @var{min} bytes have been collected.
1886 @var{min} may be a number of bytes, or it may include a unit as a
1887 suffix, such as @code{MiB} for mebibytes and @code{GB} for gigabytes
1888 (@pxref{Block size, size specifications,, coreutils, GNU Coreutils}).
1890 When @var{min} is omitted, collect all the garbage.
1894 Attempt to delete all the store files and directories specified as
1895 arguments. This fails if some of the files are not in the store, or if
1896 they are still live.
1898 @item --list-failures
1899 List store items corresponding to cached build failures.
1901 This prints nothing unless the daemon was started with
1902 @option{--cache-failures} (@pxref{Invoking guix-daemon,
1903 @option{--cache-failures}}).
1905 @item --clear-failures
1906 Remove the specified store items from the failed-build cache.
1908 Again, this option only makes sense when the daemon is started with
1909 @option{--cache-failures}. Otherwise, it does nothing.
1912 Show the list of dead files and directories still present in the
1913 store---i.e., files and directories no longer reachable from any root.
1916 Show the list of live store files and directories.
1920 In addition, the references among existing store files can be queried:
1926 List the references (respectively, the referrers) of store files given
1932 List the requisites of the store files passed as arguments. Requisites
1933 include the store files themselves, their references, and the references
1934 of these, recursively. In other words, the returned list is the
1935 @dfn{transitive closure} of the store files.
1937 @xref{Invoking guix size}, for a tool to profile the size of the closure
1938 of an element. @xref{Invoking guix graph}, for a tool to visualize
1939 the graph of references.
1943 Lastly, the following options allow you to check the integrity of the
1944 store and to control disk usage.
1948 @item --verify[=@var{options}]
1949 @cindex integrity, of the store
1950 @cindex integrity checking
1951 Verify the integrity of the store.
1953 By default, make sure that all the store items marked as valid in the
1954 database of the daemon actually exist in @file{/gnu/store}.
1956 When provided, @var{options} must be a comma-separated list containing one
1957 or more of @code{contents} and @code{repair}.
1959 When passing @option{--verify=contents}, the daemon computse the
1960 content hash of each store item and compares it against its hash in the
1961 database. Hash mismatches are reported as data corruptions. Because it
1962 traverses @emph{all the files in the store}, this command can take a
1963 long time, especially on systems with a slow disk drive.
1965 @cindex repairing the store
1966 Using @option{--verify=repair} or @option{--verify=contents,repair}
1967 causes the daemon to try to repair corrupt store items by fetching
1968 substitutes for them (@pxref{Substitutes}). Because repairing is not
1969 atomic, and thus potentially dangerous, it is available only to the
1970 system administrator.
1973 @cindex deduplication
1974 Optimize the store by hard-linking identical files---this is
1975 @dfn{deduplication}.
1977 The daemon performs deduplication after each successful build or archive
1978 import, unless it was started with @code{--disable-deduplication}
1979 (@pxref{Invoking guix-daemon, @code{--disable-deduplication}}). Thus,
1980 this option is primarily useful when the daemon was running with
1981 @code{--disable-deduplication}.
1985 @node Invoking guix pull
1986 @section Invoking @command{guix pull}
1988 Packages are installed or upgraded to the latest version available in
1989 the distribution currently available on your local machine. To update
1990 that distribution, along with the Guix tools, you must run @command{guix
1991 pull}: the command downloads the latest Guix source code and package
1992 descriptions, and deploys it.
1994 On completion, @command{guix package} will use packages and package
1995 versions from this just-retrieved copy of Guix. Not only that, but all
1996 the Guix commands and Scheme modules will also be taken from that latest
1997 version. New @command{guix} sub-commands added by the update also
2000 Any user can update their Guix copy using @command{guix pull}, and the
2001 effect is limited to the user who run @command{guix pull}. For
2002 instance, when user @code{root} runs @command{guix pull}, this has no
2003 effect on the version of Guix that user @code{alice} sees, and vice
2004 versa@footnote{Under the hood, @command{guix pull} updates the
2005 @file{~/.config/guix/latest} symbolic link to point to the latest Guix,
2006 and the @command{guix} command loads code from there.}.
2008 The @command{guix pull} command is usually invoked with no arguments,
2009 but it supports the following options:
2013 Produce verbose output, writing build logs to the standard error output.
2015 @item --url=@var{url}
2016 Download the source tarball of Guix from @var{url}.
2018 By default, the tarball is taken from its canonical address at
2019 @code{gnu.org}, for the stable branch of Guix.
2022 Use the bootstrap Guile to build the latest Guix. This option is only
2023 useful to Guix developers.
2027 @node Invoking guix archive
2028 @section Invoking @command{guix archive}
2030 The @command{guix archive} command allows users to @dfn{export} files
2031 from the store into a single archive, and to later @dfn{import} them.
2032 In particular, it allows store files to be transferred from one machine
2033 to the store on another machine.
2035 To export store files as an archive to standard output, run:
2038 guix archive --export @var{options} @var{specifications}...
2041 @var{specifications} may be either store file names or package
2042 specifications, as for @command{guix package} (@pxref{Invoking guix
2043 package}). For instance, the following command creates an archive
2044 containing the @code{gui} output of the @code{git} package and the main
2045 output of @code{emacs}:
2048 guix archive --export git:gui /gnu/store/...-emacs-24.3 > great.nar
2051 If the specified packages are not built yet, @command{guix archive}
2052 automatically builds them. The build process may be controlled with the
2053 common build options (@pxref{Common Build Options}).
2055 To transfer the @code{emacs} package to a machine connected over SSH,
2059 guix archive --export -r emacs | ssh the-machine guix archive --import
2063 Similarly, a complete user profile may be transferred from one machine
2064 to another like this:
2067 guix archive --export -r $(readlink -f ~/.guix-profile) | \
2068 ssh the-machine guix-archive --import
2072 However, note that, in both examples, all of @code{emacs} and the
2073 profile as well as all of their dependencies are transferred (due to
2074 @code{-r}), regardless of what is already available in the store on the
2075 target machine. The @code{--missing} option can help figure out which
2076 items are missing from the target store.
2078 Archives are stored in the ``Nix archive'' or ``Nar'' format, which is
2079 comparable in spirit to `tar', but with a few noteworthy differences
2080 that make it more appropriate for our purposes. First, rather than
2081 recording all Unix metadata for each file, the Nar format only mentions
2082 the file type (regular, directory, or symbolic link); Unix permissions
2083 and owner/group are dismissed. Second, the order in which directory
2084 entries are stored always follows the order of file names according to
2085 the C locale collation order. This makes archive production fully
2088 When exporting, the daemon digitally signs the contents of the archive,
2089 and that digital signature is appended. When importing, the daemon
2090 verifies the signature and rejects the import in case of an invalid
2091 signature or if the signing key is not authorized.
2092 @c FIXME: Add xref to daemon doc about signatures.
2094 The main options are:
2098 Export the specified store files or packages (see below.) Write the
2099 resulting archive to the standard output.
2101 Dependencies are @emph{not} included in the output, unless
2102 @code{--recursive} is passed.
2106 When combined with @code{--export}, this instructs @command{guix
2107 archive} to include dependencies of the given items in the archive.
2108 Thus, the resulting archive is self-contained: it contains the closure
2109 of the exported store items.
2112 Read an archive from the standard input, and import the files listed
2113 therein into the store. Abort if the archive has an invalid digital
2114 signature, or if it is signed by a public key not among the authorized
2115 keys (see @code{--authorize} below.)
2118 Read a list of store file names from the standard input, one per line,
2119 and write on the standard output the subset of these files missing from
2122 @item --generate-key[=@var{parameters}]
2123 @cindex signing, archives
2124 Generate a new key pair for the daemon. This is a prerequisite before
2125 archives can be exported with @code{--export}. Note that this operation
2126 usually takes time, because it needs to gather enough entropy to
2127 generate the key pair.
2129 The generated key pair is typically stored under @file{/etc/guix}, in
2130 @file{signing-key.pub} (public key) and @file{signing-key.sec} (private
2131 key, which must be kept secret.) When @var{parameters} is omitted,
2132 an ECDSA key using the Ed25519 curve is generated, or, for Libgcrypt
2133 versions before 1.6.0, it is a 4096-bit RSA key.
2134 Alternatively, @var{parameters} can specify
2135 @code{genkey} parameters suitable for Libgcrypt (@pxref{General
2136 public-key related Functions, @code{gcry_pk_genkey},, gcrypt, The
2137 Libgcrypt Reference Manual}).
2140 @cindex authorizing, archives
2141 Authorize imports signed by the public key passed on standard input.
2142 The public key must be in ``s-expression advanced format''---i.e., the
2143 same format as the @file{signing-key.pub} file.
2145 The list of authorized keys is kept in the human-editable file
2146 @file{/etc/guix/acl}. The file contains
2147 @url{http://people.csail.mit.edu/rivest/Sexp.txt, ``advanced-format
2148 s-expressions''} and is structured as an access-control list in the
2149 @url{http://theworld.com/~cme/spki.txt, Simple Public-Key Infrastructure
2152 @item --extract=@var{directory}
2153 @itemx -x @var{directory}
2154 Read a single-item archive as served by substitute servers
2155 (@pxref{Substitutes}) and extract it to @var{directory}. This is a
2156 low-level operation needed in only very narrow use cases; see below.
2158 For example, the following command extracts the substitute for Emacs
2159 served by @code{hydra.gnu.org} to @file{/tmp/emacs}:
2163 http://hydra.gnu.org/nar/@dots{}-emacs-24.5 \
2164 | bunzip2 | guix archive -x /tmp/emacs
2167 Single-item archives are different from multiple-item archives produced
2168 by @command{guix archive --export}; they contain a single store item,
2169 and they do @emph{not} embed a signature. Thus this operation does
2170 @emph{no} signature verification and its output should be considered
2173 The primary purpose of this operation is to facilitate inspection of
2174 archive contents coming from possibly untrusted substitute servers.
2178 @c *********************************************************************
2181 @c *********************************************************************
2182 @node Programming Interface
2183 @chapter Programming Interface
2185 GNU Guix provides several Scheme programming interfaces (APIs) to
2186 define, build, and query packages. The first interface allows users to
2187 write high-level package definitions. These definitions refer to
2188 familiar packaging concepts, such as the name and version of a package,
2189 its build system, and its dependencies. These definitions can then be
2190 turned into concrete build actions.
2192 Build actions are performed by the Guix daemon, on behalf of users. In a
2193 standard setup, the daemon has write access to the store---the
2194 @file{/gnu/store} directory---whereas users do not. The recommended
2195 setup also has the daemon perform builds in chroots, under a specific
2196 build users, to minimize interference with the rest of the system.
2199 Lower-level APIs are available to interact with the daemon and the
2200 store. To instruct the daemon to perform a build action, users actually
2201 provide it with a @dfn{derivation}. A derivation is a low-level
2202 representation of the build actions to be taken, and the environment in
2203 which they should occur---derivations are to package definitions what
2204 assembly is to C programs. The term ``derivation'' comes from the fact
2205 that build results @emph{derive} from them.
2207 This chapter describes all these APIs in turn, starting from high-level
2208 package definitions.
2211 * Defining Packages:: Defining new packages.
2212 * Build Systems:: Specifying how packages are built.
2213 * The Store:: Manipulating the package store.
2214 * Derivations:: Low-level interface to package derivations.
2215 * The Store Monad:: Purely functional interface to the store.
2216 * G-Expressions:: Manipulating build expressions.
2219 @node Defining Packages
2220 @section Defining Packages
2222 The high-level interface to package definitions is implemented in the
2223 @code{(guix packages)} and @code{(guix build-system)} modules. As an
2224 example, the package definition, or @dfn{recipe}, for the GNU Hello
2225 package looks like this:
2228 (define-module (gnu packages hello)
2229 #:use-module (guix packages)
2230 #:use-module (guix download)
2231 #:use-module (guix build-system gnu)
2232 #:use-module (guix licenses)
2233 #:use-module (gnu packages gawk))
2235 (define-public hello
2241 (uri (string-append "mirror://gnu/hello/hello-" version
2245 "0ssi1wpaf7plaswqqjwigppsg5fyh99vdlb9kzl7c9lng89ndq1i"))))
2246 (build-system gnu-build-system)
2247 (arguments `(#:configure-flags '("--enable-silent-rules")))
2248 (inputs `(("gawk" ,gawk)))
2249 (synopsis "Hello, GNU world: An example GNU package")
2250 (description "Guess what GNU Hello prints!")
2251 (home-page "http://www.gnu.org/software/hello/")
2256 Without being a Scheme expert, the reader may have guessed the meaning
2257 of the various fields here. This expression binds the variable
2258 @code{hello} to a @code{<package>} object, which is essentially a record
2259 (@pxref{SRFI-9, Scheme records,, guile, GNU Guile Reference Manual}).
2260 This package object can be inspected using procedures found in the
2261 @code{(guix packages)} module; for instance, @code{(package-name hello)}
2262 returns---surprise!---@code{"hello"}.
2264 With luck, you may be able to import part or all of the definition of
2265 the package you are interested in from another repository, using the
2266 @code{guix import} command (@pxref{Invoking guix import}).
2268 In the example above, @var{hello} is defined in a module of its own,
2269 @code{(gnu packages hello)}. Technically, this is not strictly
2270 necessary, but it is convenient to do so: all the packages defined in
2271 modules under @code{(gnu packages @dots{})} are automatically known to
2272 the command-line tools (@pxref{Package Modules}).
2274 There are a few points worth noting in the above package definition:
2278 The @code{source} field of the package is an @code{<origin>} object
2279 (@pxref{origin Reference}, for the complete reference).
2280 Here, the @code{url-fetch} method from @code{(guix download)} is used,
2281 meaning that the source is a file to be downloaded over FTP or HTTP.
2283 The @code{mirror://gnu} prefix instructs @code{url-fetch} to use one of
2284 the GNU mirrors defined in @code{(guix download)}.
2286 The @code{sha256} field specifies the expected SHA256 hash of the file
2287 being downloaded. It is mandatory, and allows Guix to check the
2288 integrity of the file. The @code{(base32 @dots{})} form introduces the
2289 base32 representation of the hash. You can obtain this information with
2290 @code{guix download} (@pxref{Invoking guix download}) and @code{guix
2291 hash} (@pxref{Invoking guix hash}).
2294 When needed, the @code{origin} form can also have a @code{patches} field
2295 listing patches to be applied, and a @code{snippet} field giving a
2296 Scheme expression to modify the source code.
2299 @cindex GNU Build System
2300 The @code{build-system} field specifies the procedure to build the
2301 package (@pxref{Build Systems}). Here, @var{gnu-build-system}
2302 represents the familiar GNU Build System, where packages may be
2303 configured, built, and installed with the usual @code{./configure &&
2304 make && make check && make install} command sequence.
2307 The @code{arguments} field specifies options for the build system
2308 (@pxref{Build Systems}). Here it is interpreted by
2309 @var{gnu-build-system} as a request run @file{configure} with the
2310 @code{--enable-silent-rules} flag.
2313 The @code{inputs} field specifies inputs to the build process---i.e.,
2314 build-time or run-time dependencies of the package. Here, we define an
2315 input called @code{"gawk"} whose value is that of the @var{gawk}
2316 variable; @var{gawk} is itself bound to a @code{<package>} object.
2318 Note that GCC, Coreutils, Bash, and other essential tools do not need to
2319 be specified as inputs here. Instead, @var{gnu-build-system} takes care
2320 of ensuring that they are present (@pxref{Build Systems}).
2322 However, any other dependencies need to be specified in the
2323 @code{inputs} field. Any dependency not specified here will simply be
2324 unavailable to the build process, possibly leading to a build failure.
2327 @xref{package Reference}, for a full description of possible fields.
2329 Once a package definition is in place, the
2330 package may actually be built using the @code{guix build} command-line
2331 tool (@pxref{Invoking guix build}). You can easily jump back to the
2332 package definition using the @command{guix edit} command
2333 (@pxref{Invoking guix edit}).
2334 @xref{Packaging Guidelines}, for
2335 more information on how to test package definitions, and
2336 @ref{Invoking guix lint}, for information on how to check a definition
2337 for style conformance.
2339 Finally, updating the package definition to a new upstream version
2340 can be partly automated by the @command{guix refresh} command
2341 (@pxref{Invoking guix refresh}).
2343 Behind the scenes, a derivation corresponding to the @code{<package>}
2344 object is first computed by the @code{package-derivation} procedure.
2345 That derivation is stored in a @code{.drv} file under @file{/gnu/store}.
2346 The build actions it prescribes may then be realized by using the
2347 @code{build-derivations} procedure (@pxref{The Store}).
2349 @deffn {Scheme Procedure} package-derivation @var{store} @var{package} [@var{system}]
2350 Return the @code{<derivation>} object of @var{package} for @var{system}
2351 (@pxref{Derivations}).
2353 @var{package} must be a valid @code{<package>} object, and @var{system}
2354 must be a string denoting the target system type---e.g.,
2355 @code{"x86_64-linux"} for an x86_64 Linux-based GNU system. @var{store}
2356 must be a connection to the daemon, which operates on the store
2357 (@pxref{The Store}).
2361 @cindex cross-compilation
2362 Similarly, it is possible to compute a derivation that cross-builds a
2363 package for some other system:
2365 @deffn {Scheme Procedure} package-cross-derivation @var{store} @
2366 @var{package} @var{target} [@var{system}]
2367 Return the @code{<derivation>} object of @var{package} cross-built from
2368 @var{system} to @var{target}.
2370 @var{target} must be a valid GNU triplet denoting the target hardware
2371 and operating system, such as @code{"mips64el-linux-gnu"}
2372 (@pxref{Configuration Names, GNU configuration triplets,, configure, GNU
2373 Configure and Build System}).
2377 * package Reference :: The package data type.
2378 * origin Reference:: The origin data type.
2382 @node package Reference
2383 @subsection @code{package} Reference
2385 This section summarizes all the options available in @code{package}
2386 declarations (@pxref{Defining Packages}).
2388 @deftp {Data Type} package
2389 This is the data type representing a package recipe.
2393 The name of the package, as a string.
2395 @item @code{version}
2396 The version of the package, as a string.
2399 An origin object telling how the source code for the package should be
2400 acquired (@pxref{origin Reference}).
2402 @item @code{build-system}
2403 The build system that should be used to build the package (@pxref{Build
2406 @item @code{arguments} (default: @code{'()})
2407 The arguments that should be passed to the build system. This is a
2408 list, typically containing sequential keyword-value pairs.
2410 @item @code{inputs} (default: @code{'()})
2411 @itemx @code{native-inputs} (default: @code{'()})
2412 @itemx @code{propagated-inputs} (default: @code{'()})
2413 @cindex inputs, of packages
2414 These fields list dependencies of the package. Each one is a list of
2415 tuples, where each tuple has a label for the input (a string) as its
2416 first element, a package, origin, or derivation as its second element,
2417 and optionally the name of the output thereof that should be used, which
2418 defaults to @code{"out"} (@pxref{Packages with Multiple Outputs}, for
2419 more on package outputs). For example, the list below specifies three
2423 `(("libffi" ,libffi)
2424 ("libunistring" ,libunistring)
2425 ("glib:bin" ,glib "bin")) ;the "bin" output of Glib
2428 @cindex cross compilation, package dependencies
2429 The distinction between @code{native-inputs} and @code{inputs} is
2430 necessary when considering cross-compilation. When cross-compiling,
2431 dependencies listed in @code{inputs} are built for the @emph{target}
2432 architecture; conversely, dependencies listed in @code{native-inputs}
2433 are built for the architecture of the @emph{build} machine.
2435 @code{native-inputs} is typically used to list tools needed at
2436 build time, but not at run time, such as Autoconf, Automake, pkg-config,
2437 Gettext, or Bison. @command{guix lint} can report likely mistakes in
2438 this area (@pxref{Invoking guix lint}).
2440 @anchor{package-propagated-inputs}
2441 Lastly, @code{propagated-inputs} is similar to @code{inputs}, but the
2442 specified packages will be automatically installed alongside the package
2443 they belong to (@pxref{package-cmd-propagated-inputs, @command{guix
2444 package}}, for information on how @command{guix package} deals with
2447 For example this is necessary when a C/C++ library needs headers of
2448 another library to compile, or when a pkg-config file refers to another
2449 one @i{via} its @code{Requires} field.
2451 Another example where @code{propagated-inputs} is useful is for languages
2452 that lack a facility to record the run-time search path akin to the
2453 @code{RUNPATH}of ELF files; this includes Guile, Python, Perl, GHC, and
2454 more. To ensure that libraries written in those languages can find
2455 library code they depend on at run time, run-time dependencies must be
2456 listed in @code{propagated-inputs} rather than @code{inputs}.
2458 @item @code{self-native-input?} (default: @code{#f})
2459 This is a Boolean field telling whether the package should use itself as
2460 a native input when cross-compiling.
2462 @item @code{outputs} (default: @code{'("out")})
2463 The list of output names of the package. @xref{Packages with Multiple
2464 Outputs}, for typical uses of additional outputs.
2466 @item @code{native-search-paths} (default: @code{'()})
2467 @itemx @code{search-paths} (default: @code{'()})
2468 A list of @code{search-path-specification} objects describing
2469 search-path environment variables honored by the package.
2471 @item @code{replacement} (default: @code{#f})
2472 This must be either @code{#f} or a package object that will be used as a
2473 @dfn{replacement} for this package. @xref{Security Updates, grafts},
2476 @item @code{synopsis}
2477 A one-line description of the package.
2479 @item @code{description}
2480 A more elaborate description of the package.
2482 @item @code{license}
2483 The license of the package; a value from @code{(guix licenses)},
2484 or a list of such values.
2486 @item @code{home-page}
2487 The URL to the home-page of the package, as a string.
2489 @item @code{supported-systems} (default: @var{%supported-systems})
2490 The list of systems supported by the package, as strings of the form
2491 @code{architecture-kernel}, for example @code{"x86_64-linux"}.
2493 @item @code{maintainers} (default: @code{'()})
2494 The list of maintainers of the package, as @code{maintainer} objects.
2496 @item @code{location} (default: source location of the @code{package} form)
2497 The source location of the package. It is useful to override this when
2498 inheriting from another package, in which case this field is not
2499 automatically corrected.
2504 @node origin Reference
2505 @subsection @code{origin} Reference
2507 This section summarizes all the options available in @code{origin}
2508 declarations (@pxref{Defining Packages}).
2510 @deftp {Data Type} origin
2511 This is the data type representing a source code origin.
2515 An object containing the URI of the source. The object type depends on
2516 the @code{method} (see below). For example, when using the
2517 @var{url-fetch} method of @code{(guix download)}, the valid @code{uri}
2518 values are: a URL represented as a string, or a list thereof.
2521 A procedure that handles the URI.
2526 @item @var{url-fetch} from @code{(guix download)}
2527 download a file from the HTTP, HTTPS, or FTP URL specified in the
2530 @item @var{git-fetch} from @code{(guix git-download)}
2531 clone the Git version control repository, and check out the revision
2532 specified in the @code{uri} field as a @code{git-reference} object; a
2533 @code{git-reference} looks like this:
2537 (url "git://git.debian.org/git/pkg-shadow/shadow")
2538 (commit "v4.1.5.1"))
2543 A bytevector containing the SHA-256 hash of the source. Typically the
2544 @code{base32} form is used here to generate the bytevector from a
2547 @item @code{file-name} (default: @code{#f})
2548 The file name under which the source code should be saved. When this is
2549 @code{#f}, a sensible default value will be used in most cases. In case
2550 the source is fetched from a URL, the file name from the URL will be
2551 used. For version control checkouts, it is recommended to provide the
2552 file name explicitly because the default is not very descriptive.
2554 @item @code{patches} (default: @code{'()})
2555 A list of file names containing patches to be applied to the source.
2557 @item @code{snippet} (default: @code{#f})
2558 A quoted piece of code that will be run in the source directory to make
2559 any modifications, which is sometimes more convenient than a patch.
2561 @item @code{patch-flags} (default: @code{'("-p1")})
2562 A list of command-line flags that should be passed to the @code{patch}
2565 @item @code{patch-inputs} (default: @code{#f})
2566 Input packages or derivations to the patching process. When this is
2567 @code{#f}, the usual set of inputs necessary for patching are provided,
2568 such as GNU@tie{}Patch.
2570 @item @code{modules} (default: @code{'()})
2571 A list of Guile modules that should be loaded during the patching
2572 process and while running the code in the @code{snippet} field.
2574 @item @code{imported-modules} (default: @code{'()})
2575 The list of Guile modules to import in the patch derivation, for use by
2578 @item @code{patch-guile} (default: @code{#f})
2579 The Guile package that should be used in the patching process. When
2580 this is @code{#f}, a sensible default is used.
2586 @section Build Systems
2588 @cindex build system
2589 Each package definition specifies a @dfn{build system} and arguments for
2590 that build system (@pxref{Defining Packages}). This @code{build-system}
2591 field represents the build procedure of the package, as well as implicit
2592 dependencies of that build procedure.
2594 Build systems are @code{<build-system>} objects. The interface to
2595 create and manipulate them is provided by the @code{(guix build-system)}
2596 module, and actual build systems are exported by specific modules.
2598 @cindex bag (low-level package representation)
2599 Under the hood, build systems first compile package objects to
2600 @dfn{bags}. A @dfn{bag} is like a package, but with less
2601 ornamentation---in other words, a bag is a lower-level representation of
2602 a package, which includes all the inputs of that package, including some
2603 that were implicitly added by the build system. This intermediate
2604 representation is then compiled to a derivation (@pxref{Derivations}).
2606 Build systems accept an optional list of @dfn{arguments}. In package
2607 definitions, these are passed @i{via} the @code{arguments} field
2608 (@pxref{Defining Packages}). They are typically keyword arguments
2609 (@pxref{Optional Arguments, keyword arguments in Guile,, guile, GNU
2610 Guile Reference Manual}). The value of these arguments is usually
2611 evaluated in the @dfn{build stratum}---i.e., by a Guile process launched
2612 by the daemon (@pxref{Derivations}).
2614 The main build system is @var{gnu-build-system}, which implements the
2615 standard build procedure for GNU and many other packages. It
2616 is provided by the @code{(guix build-system gnu)} module.
2618 @defvr {Scheme Variable} gnu-build-system
2619 @var{gnu-build-system} represents the GNU Build System, and variants
2620 thereof (@pxref{Configuration, configuration and makefile conventions,,
2621 standards, GNU Coding Standards}).
2623 @cindex build phases
2624 In a nutshell, packages using it are configured, built, and installed with
2625 the usual @code{./configure && make && make check && make install}
2626 command sequence. In practice, a few additional steps are often needed.
2627 All these steps are split up in separate @dfn{phases},
2628 notably@footnote{Please see the @code{(guix build gnu-build-system)}
2629 modules for more details about the build phases.}:
2633 Unpack the source tarball, and change the current directory to the
2634 extracted source tree. If the source is actually a directory, copy it
2635 to the build tree, and enter that directory.
2637 @item patch-source-shebangs
2638 Patch shebangs encountered in source files so they refer to the right
2639 store file names. For instance, this changes @code{#!/bin/sh} to
2640 @code{#!/gnu/store/@dots{}-bash-4.3/bin/sh}.
2643 Run the @file{configure} script with a number of default options, such
2644 as @code{--prefix=/gnu/store/@dots{}}, as well as the options specified
2645 by the @code{#:configure-flags} argument.
2648 Run @code{make} with the list of flags specified with
2649 @code{#:make-flags}. If the @code{#:parallel-build?} argument is true
2650 (the default), build with @code{make -j}.
2653 Run @code{make check}, or some other target specified with
2654 @code{#:test-target}, unless @code{#:tests? #f} is passed. If the
2655 @code{#:parallel-tests?} argument is true (the default), run @code{make
2659 Run @code{make install} with the flags listed in @code{#:make-flags}.
2661 @item patch-shebangs
2662 Patch shebangs on the installed executable files.
2665 Strip debugging symbols from ELF files (unless @code{#:strip-binaries?}
2666 is false), copying them to the @code{debug} output when available
2667 (@pxref{Installing Debugging Files}).
2670 @vindex %standard-phases
2671 The build-side module @code{(guix build gnu-build-system)} defines
2672 @var{%standard-phases} as the default list of build phases.
2673 @var{%standard-phases} is a list of symbol/procedure pairs, where the
2674 procedure implements the actual phase.
2676 The list of phases used for a particular package can be changed with the
2677 @code{#:phases} parameter. For instance, passing:
2680 #:phases (modify-phases %standard-phases (delete 'configure))
2683 means that all the phases described above will be used, except the
2684 @code{configure} phase.
2686 In addition, this build system ensures that the ``standard'' environment
2687 for GNU packages is available. This includes tools such as GCC, libc,
2688 Coreutils, Bash, Make, Diffutils, grep, and sed (see the @code{(guix
2689 build-system gnu)} module for a complete list). We call these the
2690 @dfn{implicit inputs} of a package, because package definitions do not
2691 have to mention them.
2694 Other @code{<build-system>} objects are defined to support other
2695 conventions and tools used by free software packages. They inherit most
2696 of @var{gnu-build-system}, and differ mainly in the set of inputs
2697 implicitly added to the build process, and in the list of phases
2698 executed. Some of these build systems are listed below.
2700 @defvr {Scheme Variable} cmake-build-system
2701 This variable is exported by @code{(guix build-system cmake)}. It
2702 implements the build procedure for packages using the
2703 @url{http://www.cmake.org, CMake build tool}.
2705 It automatically adds the @code{cmake} package to the set of inputs.
2706 Which package is used can be specified with the @code{#:cmake}
2709 The @code{#:configure-flags} parameter is taken as a list of flags
2710 passed to the @command{cmake} command. The @code{#:build-type}
2711 parameter specifies in abstract terms the flags passed to the compiler;
2712 it defaults to @code{"RelWithDebInfo"} (short for ``release mode with
2713 debugging information''), which roughly means that code is compiled with
2714 @code{-O2 -g}, as is the case for Autoconf-based packages by default.
2717 @defvr {Scheme Variable} glib-or-gtk-build-system
2718 This variable is exported by @code{(guix build-system glib-or-gtk)}. It
2719 is intended for use with packages making use of GLib or GTK+.
2721 This build system adds the following two phases to the ones defined by
2722 @var{gnu-build-system}:
2725 @item glib-or-gtk-wrap
2726 The phase @code{glib-or-gtk-wrap} ensures that programs in
2727 @file{bin/} are able to find GLib ``schemas'' and
2728 @uref{https://developer.gnome.org/gtk3/stable/gtk-running.html, GTK+
2729 modules}. This is achieved by wrapping the programs in launch scripts
2730 that appropriately set the @code{XDG_DATA_DIRS} and @code{GTK_PATH}
2731 environment variables.
2733 It is possible to exclude specific package outputs from that wrapping
2734 process by listing their names in the
2735 @code{#:glib-or-gtk-wrap-excluded-outputs} parameter. This is useful
2736 when an output is known not to contain any GLib or GTK+ binaries, and
2737 where wrapping would gratuitously add a dependency of that output on
2740 @item glib-or-gtk-compile-schemas
2741 The phase @code{glib-or-gtk-compile-schemas} makes sure that all
2742 @uref{https://developer.gnome.org/gio/stable/glib-compile-schemas.html,
2743 GSettings schemas} of GLib are compiled. Compilation is performed by the
2744 @command{glib-compile-schemas} program. It is provided by the package
2745 @code{glib:bin} which is automatically imported by the build system.
2746 The @code{glib} package providing @command{glib-compile-schemas} can be
2747 specified with the @code{#:glib} parameter.
2750 Both phases are executed after the @code{install} phase.
2753 @defvr {Scheme Variable} python-build-system
2754 This variable is exported by @code{(guix build-system python)}. It
2755 implements the more or less standard build procedure used by Python
2756 packages, which consists in running @code{python setup.py build} and
2757 then @code{python setup.py install --prefix=/gnu/store/@dots{}}.
2759 For packages that install stand-alone Python programs under @code{bin/},
2760 it takes care of wrapping these programs so that their @code{PYTHONPATH}
2761 environment variable points to all the Python libraries they depend on.
2763 Which Python package is used can be specified with the @code{#:python}
2767 @defvr {Scheme Variable} perl-build-system
2768 This variable is exported by @code{(guix build-system perl)}. It
2769 implements the standard build procedure for Perl packages, which either
2770 consists in running @code{perl Build.PL --prefix=/gnu/store/@dots{}},
2771 followed by @code{Build} and @code{Build install}; or in running
2772 @code{perl Makefile.PL PREFIX=/gnu/store/@dots{}}, followed by
2773 @code{make} and @code{make install}, depending on which of
2774 @code{Build.PL} or @code{Makefile.PL} is present in the package
2775 distribution. Preference is given to the former if both @code{Build.PL}
2776 and @code{Makefile.PL} exist in the package distribution. This
2777 preference can be reversed by specifying @code{#t} for the
2778 @code{#:make-maker?} parameter.
2780 The initial @code{perl Makefile.PL} or @code{perl Build.PL} invocation
2781 passes flags specified by the @code{#:make-maker-flags} or
2782 @code{#:module-build-flags} parameter, respectively.
2784 Which Perl package is used can be specified with @code{#:perl}.
2787 @defvr {Scheme Variable} r-build-system
2788 This variable is exported by @code{(guix build-system r)}. It
2789 implements the build procedure used by @uref{http://r-project.org, R}
2790 packages, which essentially is little more than running @code{R CMD
2791 INSTALL --library=/gnu/store/@dots{}} in an environment where
2792 @code{R_LIBS_SITE} contains the paths to all R package inputs. Tests
2793 are run after installation using the R function
2794 @code{tools::testInstalledPackage}.
2797 @defvr {Scheme Variable} ruby-build-system
2798 This variable is exported by @code{(guix build-system ruby)}. It
2799 implements the RubyGems build procedure used by Ruby packages, which
2800 involves running @code{gem build} followed by @code{gem install}.
2802 The @code{source} field of a package that uses this build system
2803 typically references a gem archive, since this is the format that Ruby
2804 developers use when releasing their software. The build system unpacks
2805 the gem archive, potentially patches the source, runs the test suite,
2806 repackages the gem, and installs it. Additionally, directories and
2807 tarballs may be referenced to allow building unreleased gems from Git or
2808 a traditional source release tarball.
2810 Which Ruby package is used can be specified with the @code{#:ruby}
2811 parameter. A list of additional flags to be passed to the @command{gem}
2812 command can be specified with the @code{#:gem-flags} parameter.
2815 @defvr {Scheme Variable} waf-build-system
2816 This variable is exported by @code{(guix build-system waf)}. It
2817 implements a build procedure around the @code{waf} script. The common
2818 phases---@code{configure}, @code{build}, and @code{install}---are
2819 implemented by passing their names as arguments to the @code{waf}
2822 The @code{waf} script is executed by the Python interpreter. Which
2823 Python package is used to run the script can be specified with the
2824 @code{#:python} parameter.
2827 @defvr {Scheme Variable} haskell-build-system
2828 This variable is exported by @code{(guix build-system haskell)}. It
2829 implements the Cabal build procedure used by Haskell packages, which
2830 involves running @code{runhaskell Setup.hs configure
2831 --prefix=/gnu/store/@dots{}} and @code{runhaskell Setup.hs build}.
2832 Instead of installing the package by running @code{runhaskell Setup.hs
2833 install}, to avoid trying to register libraries in the read-only
2834 compiler store directory, the build system uses @code{runhaskell
2835 Setup.hs copy}, followed by @code{runhaskell Setup.hs register}. In
2836 addition, the build system generates the package documentation by
2837 running @code{runhaskell Setup.hs haddock}, unless @code{#:haddock? #f}
2838 is passed. Optional Haddock parameters can be passed with the help of
2839 the @code{#:haddock-flags} parameter. If the file @code{Setup.hs} is
2840 not found, the build system looks for @code{Setup.lhs} instead.
2842 Which Haskell compiler is used can be specified with the @code{#:haskell}
2843 parameter which defaults to @code{ghc}.
2846 @defvr {Scheme Variable} emacs-build-system
2847 This variable is exported by @code{(guix build-system emacs)}. It
2848 implements an installation procedure similar to the packaging system
2849 of Emacs itself (@pxref{Packages,,, emacs, The GNU Emacs Manual}).
2851 It first creates the @code{@var{package}-autoloads.el} file, then it
2852 byte compiles all Emacs Lisp files. Differently from the Emacs
2853 packaging system, the Info documentation files are moved to the standard
2854 documentation directory and the @file{dir} file is deleted. Each
2855 package is installed in its own directory under
2856 @file{share/emacs/site-lisp/guix.d}.
2859 Lastly, for packages that do not need anything as sophisticated, a
2860 ``trivial'' build system is provided. It is trivial in the sense that
2861 it provides basically no support: it does not pull any implicit inputs,
2862 and does not have a notion of build phases.
2864 @defvr {Scheme Variable} trivial-build-system
2865 This variable is exported by @code{(guix build-system trivial)}.
2867 This build system requires a @code{#:builder} argument. This argument
2868 must be a Scheme expression that builds the package output(s)---as
2869 with @code{build-expression->derivation} (@pxref{Derivations,
2870 @code{build-expression->derivation}}).
2879 Conceptually, the @dfn{store} is the place where derivations that have
2880 been built successfully are stored---by default, @file{/gnu/store}.
2881 Sub-directories in the store are referred to as @dfn{store paths}. The
2882 store has an associated database that contains information such as the
2883 store paths referred to by each store path, and the list of @emph{valid}
2884 store paths---paths that result from a successful build.
2886 The store is always accessed by the daemon on behalf of its clients
2887 (@pxref{Invoking guix-daemon}). To manipulate the store, clients
2888 connect to the daemon over a Unix-domain socket, send requests to it,
2889 and read the result---these are remote procedure calls, or RPCs.
2891 The @code{(guix store)} module provides procedures to connect to the
2892 daemon, and to perform RPCs. These are described below.
2894 @deffn {Scheme Procedure} open-connection [@var{file}] [#:reserve-space? #t]
2895 Connect to the daemon over the Unix-domain socket at @var{file}. When
2896 @var{reserve-space?} is true, instruct it to reserve a little bit of
2897 extra space on the file system so that the garbage collector can still
2898 operate should the disk become full. Return a server object.
2900 @var{file} defaults to @var{%default-socket-path}, which is the normal
2901 location given the options that were passed to @command{configure}.
2904 @deffn {Scheme Procedure} close-connection @var{server}
2905 Close the connection to @var{server}.
2908 @defvr {Scheme Variable} current-build-output-port
2909 This variable is bound to a SRFI-39 parameter, which refers to the port
2910 where build and error logs sent by the daemon should be written.
2913 Procedures that make RPCs all take a server object as their first
2916 @deffn {Scheme Procedure} valid-path? @var{server} @var{path}
2917 @cindex invalid store items
2918 Return @code{#t} when @var{path} designates a valid store item and
2919 @code{#f} otherwise (an invalid item may exist on disk but still be
2920 invalid, for instance because it is the result of an aborted or failed
2923 A @code{&nix-protocol-error} condition is raised if @var{path} is not
2924 prefixed by the store directory (@file{/gnu/store}).
2927 @deffn {Scheme Procedure} add-text-to-store @var{server} @var{name} @var{text} [@var{references}]
2928 Add @var{text} under file @var{name} in the store, and return its store
2929 path. @var{references} is the list of store paths referred to by the
2930 resulting store path.
2933 @deffn {Scheme Procedure} build-derivations @var{server} @var{derivations}
2934 Build @var{derivations} (a list of @code{<derivation>} objects or
2935 derivation paths), and return when the worker is done building them.
2936 Return @code{#t} on success.
2939 Note that the @code{(guix monads)} module provides a monad as well as
2940 monadic versions of the above procedures, with the goal of making it
2941 more convenient to work with code that accesses the store (@pxref{The
2945 @i{This section is currently incomplete.}
2948 @section Derivations
2951 Low-level build actions and the environment in which they are performed
2952 are represented by @dfn{derivations}. A derivation contain the
2953 following pieces of information:
2957 The outputs of the derivation---derivations produce at least one file or
2958 directory in the store, but may produce more.
2961 The inputs of the derivations, which may be other derivations or plain
2962 files in the store (patches, build scripts, etc.)
2965 The system type targeted by the derivation---e.g., @code{x86_64-linux}.
2968 The file name of a build script in the store, along with the arguments
2972 A list of environment variables to be defined.
2976 @cindex derivation path
2977 Derivations allow clients of the daemon to communicate build actions to
2978 the store. They exist in two forms: as an in-memory representation,
2979 both on the client- and daemon-side, and as files in the store whose
2980 name end in @code{.drv}---these files are referred to as @dfn{derivation
2981 paths}. Derivations paths can be passed to the @code{build-derivations}
2982 procedure to perform the build actions they prescribe (@pxref{The
2985 The @code{(guix derivations)} module provides a representation of
2986 derivations as Scheme objects, along with procedures to create and
2987 otherwise manipulate derivations. The lowest-level primitive to create
2988 a derivation is the @code{derivation} procedure:
2990 @deffn {Scheme Procedure} derivation @var{store} @var{name} @var{builder} @
2991 @var{args} [#:outputs '("out")] [#:hash #f] [#:hash-algo #f] @
2992 [#:recursive? #f] [#:inputs '()] [#:env-vars '()] @
2993 [#:system (%current-system)] [#:references-graphs #f] @
2994 [#:allowed-references #f] [#:leaked-env-vars #f] [#:local-build? #f] @
2995 [#:substitutable? #t]
2996 Build a derivation with the given arguments, and return the resulting
2997 @code{<derivation>} object.
2999 When @var{hash} and @var{hash-algo} are given, a
3000 @dfn{fixed-output derivation} is created---i.e., one whose result is
3001 known in advance, such as a file download. If, in addition,
3002 @var{recursive?} is true, then that fixed output may be an executable
3003 file or a directory and @var{hash} must be the hash of an archive
3004 containing this output.
3006 When @var{references-graphs} is true, it must be a list of file
3007 name/store path pairs. In that case, the reference graph of each store
3008 path is exported in the build environment in the corresponding file, in
3009 a simple text format.
3011 When @var{allowed-references} is true, it must be a list of store items
3012 or outputs that the derivation's output may refer to.
3014 When @var{leaked-env-vars} is true, it must be a list of strings
3015 denoting environment variables that are allowed to ``leak'' from the
3016 daemon's environment to the build environment. This is only applicable
3017 to fixed-output derivations---i.e., when @var{hash} is true. The main
3018 use is to allow variables such as @code{http_proxy} to be passed to
3019 derivations that download files.
3021 When @var{local-build?} is true, declare that the derivation is not a
3022 good candidate for offloading and should rather be built locally
3023 (@pxref{Daemon Offload Setup}). This is the case for small derivations
3024 where the costs of data transfers would outweigh the benefits.
3026 When @var{substitutable?} is false, declare that substitutes of the
3027 derivation's output should not be used (@pxref{Substitutes}). This is
3028 useful, for instance, when building packages that capture details of the
3029 host CPU instruction set.
3033 Here's an example with a shell script as its builder, assuming
3034 @var{store} is an open connection to the daemon, and @var{bash} points
3035 to a Bash executable in the store:
3038 (use-modules (guix utils)
3042 (let ((builder ; add the Bash script to the store
3043 (add-text-to-store store "my-builder.sh"
3044 "echo hello world > $out\n" '())))
3045 (derivation store "foo"
3046 bash `("-e" ,builder)
3047 #:inputs `((,bash) (,builder))
3048 #:env-vars '(("HOME" . "/homeless"))))
3049 @result{} #<derivation /gnu/store/@dots{}-foo.drv => /gnu/store/@dots{}-foo>
3052 As can be guessed, this primitive is cumbersome to use directly. A
3053 better approach is to write build scripts in Scheme, of course! The
3054 best course of action for that is to write the build code as a
3055 ``G-expression'', and to pass it to @code{gexp->derivation}. For more
3056 information, @pxref{G-Expressions}.
3058 Once upon a time, @code{gexp->derivation} did not exist and constructing
3059 derivations with build code written in Scheme was achieved with
3060 @code{build-expression->derivation}, documented below. This procedure
3061 is now deprecated in favor of the much nicer @code{gexp->derivation}.
3063 @deffn {Scheme Procedure} build-expression->derivation @var{store} @
3064 @var{name} @var{exp} @
3065 [#:system (%current-system)] [#:inputs '()] @
3066 [#:outputs '("out")] [#:hash #f] [#:hash-algo #f] @
3067 [#:recursive? #f] [#:env-vars '()] [#:modules '()] @
3068 [#:references-graphs #f] [#:allowed-references #f] @
3069 [#:local-build? #f] [#:substitutable? #t] [#:guile-for-build #f]
3070 Return a derivation that executes Scheme expression @var{exp} as a
3071 builder for derivation @var{name}. @var{inputs} must be a list of
3072 @code{(name drv-path sub-drv)} tuples; when @var{sub-drv} is omitted,
3073 @code{"out"} is assumed. @var{modules} is a list of names of Guile
3074 modules from the current search path to be copied in the store,
3075 compiled, and made available in the load path during the execution of
3076 @var{exp}---e.g., @code{((guix build utils) (guix build
3077 gnu-build-system))}.
3079 @var{exp} is evaluated in an environment where @code{%outputs} is bound
3080 to a list of output/path pairs, and where @code{%build-inputs} is bound
3081 to a list of string/output-path pairs made from @var{inputs}.
3082 Optionally, @var{env-vars} is a list of string pairs specifying the name
3083 and value of environment variables visible to the builder. The builder
3084 terminates by passing the result of @var{exp} to @code{exit}; thus, when
3085 @var{exp} returns @code{#f}, the build is considered to have failed.
3087 @var{exp} is built using @var{guile-for-build} (a derivation). When
3088 @var{guile-for-build} is omitted or is @code{#f}, the value of the
3089 @code{%guile-for-build} fluid is used instead.
3091 See the @code{derivation} procedure for the meaning of
3092 @var{references-graphs}, @var{allowed-references}, @var{local-build?},
3093 and @var{substitutable?}.
3097 Here's an example of a single-output derivation that creates a directory
3098 containing one file:
3101 (let ((builder '(let ((out (assoc-ref %outputs "out")))
3102 (mkdir out) ; create /gnu/store/@dots{}-goo
3103 (call-with-output-file (string-append out "/test")
3105 (display '(hello guix) p))))))
3106 (build-expression->derivation store "goo" builder))
3108 @result{} #<derivation /gnu/store/@dots{}-goo.drv => @dots{}>
3112 @node The Store Monad
3113 @section The Store Monad
3117 The procedures that operate on the store described in the previous
3118 sections all take an open connection to the build daemon as their first
3119 argument. Although the underlying model is functional, they either have
3120 side effects or depend on the current state of the store.
3122 The former is inconvenient: the connection to the build daemon has to be
3123 carried around in all those functions, making it impossible to compose
3124 functions that do not take that parameter with functions that do. The
3125 latter can be problematic: since store operations have side effects
3126 and/or depend on external state, they have to be properly sequenced.
3128 @cindex monadic values
3129 @cindex monadic functions
3130 This is where the @code{(guix monads)} module comes in. This module
3131 provides a framework for working with @dfn{monads}, and a particularly
3132 useful monad for our uses, the @dfn{store monad}. Monads are a
3133 construct that allows two things: associating ``context'' with values
3134 (in our case, the context is the store), and building sequences of
3135 computations (here computations include accesses to the store.) Values
3136 in a monad---values that carry this additional context---are called
3137 @dfn{monadic values}; procedures that return such values are called
3138 @dfn{monadic procedures}.
3140 Consider this ``normal'' procedure:
3143 (define (sh-symlink store)
3144 ;; Return a derivation that symlinks the 'bash' executable.
3145 (let* ((drv (package-derivation store bash))
3146 (out (derivation->output-path drv))
3147 (sh (string-append out "/bin/bash")))
3148 (build-expression->derivation store "sh"
3149 `(symlink ,sh %output))))
3152 Using @code{(guix monads)} and @code{(guix gexp)}, it may be rewritten
3153 as a monadic function:
3156 (define (sh-symlink)
3157 ;; Same, but return a monadic value.
3158 (mlet %store-monad ((drv (package->derivation bash)))
3159 (gexp->derivation "sh"
3160 #~(symlink (string-append #$drv "/bin/bash")
3164 There several things to note in the second version: the @code{store}
3165 parameter is now implicit and is ``threaded'' in the calls to the
3166 @code{package->derivation} and @code{gexp->derivation} monadic
3167 procedures, and the monadic value returned by @code{package->derivation}
3168 is @dfn{bound} using @code{mlet} instead of plain @code{let}.
3170 As it turns out, the call to @code{package->derivation} can even be
3171 omitted since it will take place implicitly, as we will see later
3172 (@pxref{G-Expressions}):
3175 (define (sh-symlink)
3176 (gexp->derivation "sh"
3177 #~(symlink (string-append #$bash "/bin/bash")
3182 @c <https://syntaxexclamation.wordpress.com/2014/06/26/escaping-continuations/>
3183 @c for the funny quote.
3184 Calling the monadic @code{sh-symlink} has no effect. As someone once
3185 said, ``you exit a monad like you exit a building on fire: by running''.
3186 So, to exit the monad and get the desired effect, one must use
3187 @code{run-with-store}:
3190 (run-with-store (open-connection) (sh-symlink))
3191 @result{} /gnu/store/...-sh-symlink
3194 Note that the @code{(guix monad-repl)} module extends the Guile REPL with
3195 new ``meta-commands'' to make it easier to deal with monadic procedures:
3196 @code{run-in-store}, and @code{enter-store-monad}. The former is used
3197 to ``run'' a single monadic value through the store:
3200 scheme@@(guile-user)> ,run-in-store (package->derivation hello)
3201 $1 = #<derivation /gnu/store/@dots{}-hello-2.9.drv => @dots{}>
3204 The latter enters a recursive REPL, where all the return values are
3205 automatically run through the store:
3208 scheme@@(guile-user)> ,enter-store-monad
3209 store-monad@@(guile-user) [1]> (package->derivation hello)
3210 $2 = #<derivation /gnu/store/@dots{}-hello-2.9.drv => @dots{}>
3211 store-monad@@(guile-user) [1]> (text-file "foo" "Hello!")
3212 $3 = "/gnu/store/@dots{}-foo"
3213 store-monad@@(guile-user) [1]> ,q
3214 scheme@@(guile-user)>
3218 Note that non-monadic values cannot be returned in the
3219 @code{store-monad} REPL.
3221 The main syntactic forms to deal with monads in general are provided by
3222 the @code{(guix monads)} module and are described below.
3224 @deffn {Scheme Syntax} with-monad @var{monad} @var{body} ...
3225 Evaluate any @code{>>=} or @code{return} forms in @var{body} as being
3229 @deffn {Scheme Syntax} return @var{val}
3230 Return a monadic value that encapsulates @var{val}.
3233 @deffn {Scheme Syntax} >>= @var{mval} @var{mproc} ...
3234 @dfn{Bind} monadic value @var{mval}, passing its ``contents'' to monadic
3235 procedures @var{mproc}@dots{}@footnote{This operation is commonly
3236 referred to as ``bind'', but that name denotes an unrelated procedure in
3237 Guile. Thus we use this somewhat cryptic symbol inherited from the
3238 Haskell language.}. There can be one @var{mproc} or several of them, as
3243 (with-monad %state-monad
3245 (lambda (x) (return (+ 1 x)))
3246 (lambda (x) (return (* 2 x)))))
3250 @result{} some-state
3254 @deffn {Scheme Syntax} mlet @var{monad} ((@var{var} @var{mval}) ...) @
3256 @deffnx {Scheme Syntax} mlet* @var{monad} ((@var{var} @var{mval}) ...) @
3258 Bind the variables @var{var} to the monadic values @var{mval} in
3259 @var{body}. The form (@var{var} -> @var{val}) binds @var{var} to the
3260 ``normal'' value @var{val}, as per @code{let}.
3262 @code{mlet*} is to @code{mlet} what @code{let*} is to @code{let}
3263 (@pxref{Local Bindings,,, guile, GNU Guile Reference Manual}).
3266 @deffn {Scheme System} mbegin @var{monad} @var{mexp} ...
3267 Bind @var{mexp} and the following monadic expressions in sequence,
3268 returning the result of the last expression.
3270 This is akin to @code{mlet}, except that the return values of the
3271 monadic expressions are ignored. In that sense, it is analogous to
3272 @code{begin}, but applied to monadic expressions.
3276 The @code{(guix monads)} module provides the @dfn{state monad}, which
3277 allows an additional value---the state---to be @emph{threaded} through
3278 monadic procedure calls.
3280 @defvr {Scheme Variable} %state-monad
3281 The state monad. Procedures in the state monad can access and change
3282 the state that is threaded.
3284 Consider the example below. The @code{square} procedure returns a value
3285 in the state monad. It returns the square of its argument, but also
3286 increments the current state value:
3290 (mlet %state-monad ((count (current-state)))
3291 (mbegin %state-monad
3292 (set-current-state (+ 1 count))
3295 (run-with-state (sequence %state-monad (map square (iota 3))) 0)
3300 When ``run'' through @var{%state-monad}, we obtain that additional state
3301 value, which is the number of @code{square} calls.
3304 @deffn {Monadic Procedure} current-state
3305 Return the current state as a monadic value.
3308 @deffn {Monadic Procedure} set-current-state @var{value}
3309 Set the current state to @var{value} and return the previous state as a
3313 @deffn {Monadic Procedure} state-push @var{value}
3314 Push @var{value} to the current state, which is assumed to be a list,
3315 and return the previous state as a monadic value.
3318 @deffn {Monadic Procedure} state-pop
3319 Pop a value from the current state and return it as a monadic value.
3320 The state is assumed to be a list.
3323 @deffn {Scheme Procedure} run-with-state @var{mval} [@var{state}]
3324 Run monadic value @var{mval} starting with @var{state} as the initial
3325 state. Return two values: the resulting value, and the resulting state.
3328 The main interface to the store monad, provided by the @code{(guix
3329 store)} module, is as follows.
3331 @defvr {Scheme Variable} %store-monad
3332 The store monad---an alias for @var{%state-monad}.
3334 Values in the store monad encapsulate accesses to the store. When its
3335 effect is needed, a value of the store monad must be ``evaluated'' by
3336 passing it to the @code{run-with-store} procedure (see below.)
3339 @deffn {Scheme Procedure} run-with-store @var{store} @var{mval} [#:guile-for-build] [#:system (%current-system)]
3340 Run @var{mval}, a monadic value in the store monad, in @var{store}, an
3341 open store connection.
3344 @deffn {Monadic Procedure} text-file @var{name} @var{text} [@var{references}]
3345 Return as a monadic value the absolute file name in the store of the file
3346 containing @var{text}, a string. @var{references} is a list of store items that the
3347 resulting text file refers to; it defaults to the empty list.
3350 @deffn {Monadic Procedure} interned-file @var{file} [@var{name}] @
3352 Return the name of @var{file} once interned in the store. Use
3353 @var{name} as its store name, or the basename of @var{file} if
3354 @var{name} is omitted.
3356 When @var{recursive?} is true, the contents of @var{file} are added
3357 recursively; if @var{file} designates a flat file and @var{recursive?}
3358 is true, its contents are added, and its permission bits are kept.
3360 The example below adds a file to the store, under two different names:
3363 (run-with-store (open-connection)
3364 (mlet %store-monad ((a (interned-file "README"))
3365 (b (interned-file "README" "LEGU-MIN")))
3366 (return (list a b))))
3368 @result{} ("/gnu/store/rwm@dots{}-README" "/gnu/store/44i@dots{}-LEGU-MIN")
3373 The @code{(guix packages)} module exports the following package-related
3376 @deffn {Monadic Procedure} package-file @var{package} [@var{file}] @
3377 [#:system (%current-system)] [#:target #f] @
3380 value in the absolute file name of @var{file} within the @var{output}
3381 directory of @var{package}. When @var{file} is omitted, return the name
3382 of the @var{output} directory of @var{package}. When @var{target} is
3383 true, use it as a cross-compilation target triplet.
3386 @deffn {Monadic Procedure} package->derivation @var{package} [@var{system}]
3387 @deffnx {Monadic Procedure} package->cross-derivation @var{package} @
3388 @var{target} [@var{system}]
3389 Monadic version of @code{package-derivation} and
3390 @code{package-cross-derivation} (@pxref{Defining Packages}).
3395 @section G-Expressions
3397 @cindex G-expression
3398 @cindex build code quoting
3399 So we have ``derivations'', which represent a sequence of build actions
3400 to be performed to produce an item in the store (@pxref{Derivations}).
3401 These build actions are performed when asking the daemon to actually
3402 build the derivations; they are run by the daemon in a container
3403 (@pxref{Invoking guix-daemon}).
3405 @cindex strata of code
3406 It should come as no surprise that we like to write these build actions
3407 in Scheme. When we do that, we end up with two @dfn{strata} of Scheme
3408 code@footnote{The term @dfn{stratum} in this context was coined by
3409 Manuel Serrano et al.@: in the context of their work on Hop. Oleg
3410 Kiselyov, who has written insightful
3411 @url{http://okmij.org/ftp/meta-programming/#meta-scheme, essays and code
3412 on this topic}, refers to this kind of code generation as
3413 @dfn{staging}.}: the ``host code''---code that defines packages, talks
3414 to the daemon, etc.---and the ``build code''---code that actually
3415 performs build actions, such as making directories, invoking
3416 @command{make}, etc.
3418 To describe a derivation and its build actions, one typically needs to
3419 embed build code inside host code. It boils down to manipulating build
3420 code as data, and the homoiconicity of Scheme---code has a direct
3421 representation as data---comes in handy for that. But we need more than
3422 the normal @code{quasiquote} mechanism in Scheme to construct build
3425 The @code{(guix gexp)} module implements @dfn{G-expressions}, a form of
3426 S-expressions adapted to build expressions. G-expressions, or
3427 @dfn{gexps}, consist essentially of three syntactic forms: @code{gexp},
3428 @code{ungexp}, and @code{ungexp-splicing} (or simply: @code{#~},
3429 @code{#$}, and @code{#$@@}), which are comparable to
3430 @code{quasiquote}, @code{unquote}, and @code{unquote-splicing},
3431 respectivel (@pxref{Expression Syntax, @code{quasiquote},, guile,
3432 GNU Guile Reference Manual}). However, there are major differences:
3436 Gexps are meant to be written to a file and run or manipulated by other
3440 When a high-level object such as a package or derivation is unquoted
3441 inside a gexp, the result is as if its output file name had been
3445 Gexps carry information about the packages or derivations they refer to,
3446 and these dependencies are automatically added as inputs to the build
3447 processes that use them.
3450 @cindex lowering, of high-level objects in gexps
3451 This mechanism is not limited to package and derivation
3452 objects: @dfn{compilers} able to ``lower'' other high-level objects to
3453 derivations or files in the store can be defined,
3454 such that these objects can also be inserted
3455 into gexps. For example, a useful type of high-level objects that can be
3456 inserted in a gexp is ``file-like objects'', which make it easy to
3457 add files to the store and to refer to them in
3458 derivations and such (see @code{local-file} and @code{plain-file}
3461 To illustrate the idea, here is an example of a gexp:
3468 (symlink (string-append #$coreutils "/bin/ls")
3472 This gexp can be passed to @code{gexp->derivation}; we obtain a
3473 derivation that builds a directory containing exactly one symlink to
3474 @file{/gnu/store/@dots{}-coreutils-8.22/bin/ls}:
3477 (gexp->derivation "the-thing" build-exp)
3480 As one would expect, the @code{"/gnu/store/@dots{}-coreutils-8.22"} string is
3481 substituted to the reference to the @var{coreutils} package in the
3482 actual build code, and @var{coreutils} is automatically made an input to
3483 the derivation. Likewise, @code{#$output} (equivalent to @code{(ungexp
3484 output)}) is replaced by a string containing the directory name of the
3485 output of the derivation.
3487 @cindex cross compilation
3488 In a cross-compilation context, it is useful to distinguish between
3489 references to the @emph{native} build of a package---that can run on the
3490 host---versus references to cross builds of a package. To that end, the
3491 @code{#+} plays the same role as @code{#$}, but is a reference to a
3492 native package build:
3495 (gexp->derivation "vi"
3498 (system* (string-append #+coreutils "/bin/ln")
3500 (string-append #$emacs "/bin/emacs")
3501 (string-append #$output "/bin/vi")))
3502 #:target "mips64el-linux")
3506 In the example above, the native build of @var{coreutils} is used, so
3507 that @command{ln} can actually run on the host; but then the
3508 cross-compiled build of @var{emacs} is referenced.
3510 The syntactic form to construct gexps is summarized below.
3512 @deffn {Scheme Syntax} #~@var{exp}
3513 @deffnx {Scheme Syntax} (gexp @var{exp})
3514 Return a G-expression containing @var{exp}. @var{exp} may contain one
3515 or more of the following forms:
3519 @itemx (ungexp @var{obj})
3520 Introduce a reference to @var{obj}. @var{obj} may have one of the
3521 supported types, for example a package or a
3522 derivation, in which case the @code{ungexp} form is replaced by its
3523 output file name---e.g., @code{"/gnu/store/@dots{}-coreutils-8.22}.
3525 If @var{obj} is a list, it is traversed and references to supported
3526 objects are substituted similarly.
3528 If @var{obj} is another gexp, its contents are inserted and its
3529 dependencies are added to those of the containing gexp.
3531 If @var{obj} is another kind of object, it is inserted as is.
3533 @item #$@var{obj}:@var{output}
3534 @itemx (ungexp @var{obj} @var{output})
3535 This is like the form above, but referring explicitly to the
3536 @var{output} of @var{obj}---this is useful when @var{obj} produces
3537 multiple outputs (@pxref{Packages with Multiple Outputs}).
3540 @itemx #+@var{obj}:output
3541 @itemx (ungexp-native @var{obj})
3542 @itemx (ungexp-native @var{obj} @var{output})
3543 Same as @code{ungexp}, but produces a reference to the @emph{native}
3544 build of @var{obj} when used in a cross compilation context.
3546 @item #$output[:@var{output}]
3547 @itemx (ungexp output [@var{output}])
3548 Insert a reference to derivation output @var{output}, or to the main
3549 output when @var{output} is omitted.
3551 This only makes sense for gexps passed to @code{gexp->derivation}.
3554 @itemx (ungexp-splicing @var{lst})
3555 Like the above, but splices the contents of @var{lst} inside the
3559 @itemx (ungexp-native-splicing @var{lst})
3560 Like the above, but refers to native builds of the objects listed in
3565 G-expressions created by @code{gexp} or @code{#~} are run-time objects
3566 of the @code{gexp?} type (see below.)
3569 @deffn {Scheme Procedure} gexp? @var{obj}
3570 Return @code{#t} if @var{obj} is a G-expression.
3573 G-expressions are meant to be written to disk, either as code building
3574 some derivation, or as plain files in the store. The monadic procedures
3575 below allow you to do that (@pxref{The Store Monad}, for more
3576 information about monads.)
3578 @deffn {Monadic Procedure} gexp->derivation @var{name} @var{exp} @
3579 [#:system (%current-system)] [#:target #f] [#:graft? #t] @
3580 [#:hash #f] [#:hash-algo #f] @
3581 [#:recursive? #f] [#:env-vars '()] [#:modules '()] @
3582 [#:module-path @var{%load-path}] @
3583 [#:references-graphs #f] [#:allowed-references #f] @
3584 [#:leaked-env-vars #f] @
3585 [#:script-name (string-append @var{name} "-builder")] @
3586 [#:local-build? #f] [#:substitutable? #t] [#:guile-for-build #f]
3587 Return a derivation @var{name} that runs @var{exp} (a gexp) with
3588 @var{guile-for-build} (a derivation) on @var{system}; @var{exp} is
3589 stored in a file called @var{script-name}. When @var{target} is true,
3590 it is used as the cross-compilation target triplet for packages referred
3593 Make @var{modules} available in the evaluation context of @var{exp};
3594 @var{modules} is a list of names of Guile modules searched in
3595 @var{module-path} to be copied in the store, compiled, and made available in
3596 the load path during the execution of @var{exp}---e.g., @code{((guix
3597 build utils) (guix build gnu-build-system))}.
3599 @var{graft?} determines whether packages referred to by @var{exp} should be grafted when
3602 When @var{references-graphs} is true, it must be a list of tuples of one of the
3606 (@var{file-name} @var{package})
3607 (@var{file-name} @var{package} @var{output})
3608 (@var{file-name} @var{derivation})
3609 (@var{file-name} @var{derivation} @var{output})
3610 (@var{file-name} @var{store-item})
3613 The right-hand-side of each element of @var{references-graphs} is automatically made
3614 an input of the build process of @var{exp}. In the build environment, each
3615 @var{file-name} contains the reference graph of the corresponding item, in a simple
3618 @var{allowed-references} must be either @code{#f} or a list of output names and packages.
3619 In the latter case, the list denotes store items that the result is allowed to
3620 refer to. Any reference to another store item will lead to a build error.
3622 The other arguments are as for @code{derivation} (@pxref{Derivations}).
3625 @cindex file-like objects
3626 The @code{local-file}, @code{plain-file}, @code{computed-file},
3627 @code{program-file}, and @code{scheme-file} procedures below return
3628 @dfn{file-like objects}. That is, when unquoted in a G-expression,
3629 these objects lead to a file in the store. Consider this G-expression:
3632 #~(system* (string-append #$glibc "/sbin/nscd") "-f"
3633 #$(local-file "/tmp/my-nscd.conf"))
3636 The effect here is to ``intern'' @file{/tmp/my-nscd.conf} by copying it
3637 to the store. Once expanded, for instance @i{via}
3638 @code{gexp->derivation}, the G-expression refers to that copy under
3639 @file{/gnu/store}; thus, modifying or removing the file in @file{/tmp}
3640 does not have any effect on what the G-expression does.
3641 @code{plain-file} can be used similarly; it differs in that the file
3642 content is directly passed as a string.
3644 @deffn {Scheme Procedure} local-file @var{file} [@var{name}] @
3646 Return an object representing local file @var{file} to add to the store; this
3647 object can be used in a gexp. If @var{file} is a relative file name, it is looked
3648 up relative to the source file where this form appears. @var{file} will be added to
3649 the store under @var{name}--by default the base name of @var{file}.
3651 When @var{recursive?} is true, the contents of @var{file} are added recursively; if @var{file}
3652 designates a flat file and @var{recursive?} is true, its contents are added, and its
3653 permission bits are kept.
3655 This is the declarative counterpart of the @code{interned-file} monadic
3656 procedure (@pxref{The Store Monad, @code{interned-file}}).
3659 @deffn {Scheme Procedure} plain-file @var{name} @var{content}
3660 Return an object representing a text file called @var{name} with the given
3661 @var{content} (a string) to be added to the store.
3663 This is the declarative counterpart of @code{text-file}.
3666 @deffn {Scheme Procedure} computed-file @var{name} @var{gexp} @
3667 [#:modules '()] [#:options '(#:local-build? #t)]
3668 Return an object representing the store item @var{name}, a file or
3669 directory computed by @var{gexp}. @var{modules} specifies the set of
3670 modules visible in the execution context of @var{gexp}. @var{options}
3671 is a list of additional arguments to pass to @code{gexp->derivation}.
3673 This is the declarative counterpart of @code{gexp->derivation}.
3676 @deffn {Monadic Procedure} gexp->script @var{name} @var{exp}
3677 Return an executable script @var{name} that runs @var{exp} using
3678 @var{guile} with @var{modules} in its search path.
3680 The example below builds a script that simply invokes the @command{ls}
3684 (use-modules (guix gexp) (gnu packages base))
3686 (gexp->script "list-files"
3687 #~(execl (string-append #$coreutils "/bin/ls")
3691 When ``running'' it through the store (@pxref{The Store Monad,
3692 @code{run-with-store}}), we obtain a derivation that produces an
3693 executable file @file{/gnu/store/@dots{}-list-files} along these lines:
3696 #!/gnu/store/@dots{}-guile-2.0.11/bin/guile -ds
3698 (execl (string-append "/gnu/store/@dots{}-coreutils-8.22"/bin/ls")
3703 @deffn {Scheme Procedure} program-file @var{name} @var{exp} @
3704 [#:modules '()] [#:guile #f]
3705 Return an object representing the executable store item @var{name} that
3706 runs @var{gexp}. @var{guile} is the Guile package used to execute that
3707 script, and @var{modules} is the list of modules visible to that script.
3709 This is the declarative counterpart of @code{gexp->script}.
3712 @deffn {Monadic Procedure} gexp->file @var{name} @var{exp}
3713 Return a derivation that builds a file @var{name} containing @var{exp}.
3715 The resulting file holds references to all the dependencies of @var{exp}
3716 or a subset thereof.
3719 @deffn {Scheme Procedure} scheme-file @var{name} @var{exp}
3720 Return an object representing the Scheme file @var{name} that contains
3723 This is the declarative counterpart of @code{gexp->file}.
3726 @deffn {Monadic Procedure} text-file* @var{name} @var{text} @dots{}
3727 Return as a monadic value a derivation that builds a text file
3728 containing all of @var{text}. @var{text} may list, in addition to
3729 strings, objects of any type that can be used in a gexp: packages,
3730 derivations, local file objects, etc. The resulting store file holds
3731 references to all these.
3733 This variant should be preferred over @code{text-file} anytime the file
3734 to create will reference items from the store. This is typically the
3735 case when building a configuration file that embeds store file names,
3739 (define (profile.sh)
3740 ;; Return the name of a shell script in the store that
3741 ;; initializes the 'PATH' environment variable.
3742 (text-file* "profile.sh"
3743 "export PATH=" coreutils "/bin:"
3744 grep "/bin:" sed "/bin\n"))
3747 In this example, the resulting @file{/gnu/store/@dots{}-profile.sh} file
3748 will references @var{coreutils}, @var{grep}, and @var{sed}, thereby
3749 preventing them from being garbage-collected during its lifetime.
3752 @deffn {Scheme Procedure} mixed-text-file @var{name} @var{text} @dots{}
3753 Return an object representing store file @var{name} containing
3754 @var{text}. @var{text} is a sequence of strings and file-like objects,
3758 (mixed-text-file "profile"
3759 "export PATH=" coreutils "/bin:" grep "/bin")
3762 This is the declarative counterpart of @code{text-file*}.
3765 Of course, in addition to gexps embedded in ``host'' code, there are
3766 also modules containing build tools. To make it clear that they are
3767 meant to be used in the build stratum, these modules are kept in the
3768 @code{(guix build @dots{})} name space.
3770 @cindex lowering, of high-level objects in gexps
3771 Internally, high-level objects are @dfn{lowered}, using their compiler,
3772 to either derivations or store items. For instance, lowering a package
3773 yields a derivation, and lowering a @code{plain-file} yields a store
3774 item. This is achieved using the @code{lower-object} monadic procedure.
3776 @deffn {Monadic Procedure} lower-object @var{obj} [@var{system}] @
3778 Return as a value in @var{%store-monad} the derivation or store item
3779 corresponding to @var{obj} for @var{system}, cross-compiling for
3780 @var{target} if @var{target} is true. @var{obj} must be an object that
3781 has an associated gexp compiler, such as a @code{<package>}.
3785 @c *********************************************************************
3789 This section describes tools primarily targeted at developers and users
3790 who write new package definitions. They complement the Scheme
3791 programming interface of Guix in a convenient way.
3794 * Invoking guix build:: Building packages from the command line.
3795 * Invoking guix edit:: Editing package definitions.
3796 * Invoking guix download:: Downloading a file and printing its hash.
3797 * Invoking guix hash:: Computing the cryptographic hash of a file.
3798 * Invoking guix import:: Importing package definitions.
3799 * Invoking guix refresh:: Updating package definitions.
3800 * Invoking guix lint:: Finding errors in package definitions.
3801 * Invoking guix size:: Profiling disk usage.
3802 * Invoking guix graph:: Visualizing the graph of packages.
3803 * Invoking guix environment:: Setting up development environments.
3804 * Invoking guix publish:: Sharing substitutes.
3805 * Invoking guix challenge:: Challenging substitute servers.
3806 * Invoking guix container:: Process isolation.
3809 @node Invoking guix build
3810 @section Invoking @command{guix build}
3812 The @command{guix build} command builds packages or derivations and
3813 their dependencies, and prints the resulting store paths. Note that it
3814 does not modify the user's profile---this is the job of the
3815 @command{guix package} command (@pxref{Invoking guix package}). Thus,
3816 it is mainly useful for distribution developers.
3818 The general syntax is:
3821 guix build @var{options} @var{package-or-derivation}@dots{}
3824 As an example, the following command builds the latest versions of Emacs
3825 and of Guile, displays their build logs, and finally displays the
3826 resulting directories:
3829 guix build emacs guile
3832 Similarly, the following command builds all the available packages:
3835 guix build --keep-going \
3836 `guix package -A | cut -f1,2 --output-delimiter=@@`
3839 @var{package-or-derivation} may be either the name of a package found in
3840 the software distribution such as @code{coreutils} or
3841 @code{coreutils-8.20}, or a derivation such as
3842 @file{/gnu/store/@dots{}-coreutils-8.19.drv}. In the former case, a
3843 package with the corresponding name (and optionally version) is searched
3844 for among the GNU distribution modules (@pxref{Package Modules}).
3846 Alternatively, the @code{--expression} option may be used to specify a
3847 Scheme expression that evaluates to a package; this is useful when
3848 disambiguation among several same-named packages or package variants is
3851 There may be zero or more @var{options}. The available options are
3852 described in the subsections below.
3855 * Common Build Options:: Build options for most commands.
3856 * Package Transformation Options:: Creating variants of packages.
3857 * Additional Build Options:: Options specific to 'guix build'.
3860 @node Common Build Options
3861 @subsection Common Build Options
3863 A number of options that control the build process are common to
3864 @command{guix build} and other commands that can spawn builds, such as
3865 @command{guix package} or @command{guix archive}. These are the
3870 @item --load-path=@var{directory}
3871 @itemx -L @var{directory}
3872 Add @var{directory} to the front of the package module search path
3873 (@pxref{Package Modules}).
3875 This allows users to define their own packages and make them visible to
3876 the command-line tools.
3880 Keep the build tree of failed builds. Thus, if a build fail, its build
3881 tree is kept under @file{/tmp}, in a directory whose name is shown at
3882 the end of the build log. This is useful when debugging build issues.
3886 Keep going when some of the derivations fail to build; return only once
3887 all the builds have either completed or failed.
3889 The default behavior is to stop as soon as one of the specified
3890 derivations has failed.
3894 Do not build the derivations.
3897 When substituting a pre-built binary fails, fall back to building
3900 @item --substitute-urls=@var{urls}
3901 @anchor{client-substitute-urls}
3902 Consider @var{urls} the whitespace-separated list of substitute source
3903 URLs, overriding the default list of URLs of @command{guix-daemon}
3904 (@pxref{daemon-substitute-urls,, @command{guix-daemon} URLs}).
3906 This means that substitutes may be downloaded from @var{urls}, provided
3907 they are signed by a key authorized by the system administrator
3908 (@pxref{Substitutes}).
3910 @item --no-substitutes
3911 Do not use substitutes for build products. That is, always build things
3912 locally instead of allowing downloads of pre-built binaries
3913 (@pxref{Substitutes}).
3915 @item --rounds=@var{n}
3916 Build each derivation @var{n} times in a row, and raise an error if
3917 consecutive build results are not bit-for-bit identical.
3919 This is a useful way to detect non-deterministic builds processes.
3920 Non-deterministic build processes are a problem because they make it
3921 practically impossible for users to @emph{verify} whether third-party
3922 binaries are genuine. @xref{Invoking guix challenge}, for more.
3924 Note that, currently, the differing build results are not kept around,
3925 so you will have to manually investigate in case of an error---e.g., by
3926 stashing one of the build results with @code{guix archive --export},
3927 then rebuilding, and finally comparing the two results.
3929 @item --no-build-hook
3930 Do not attempt to offload builds @i{via} the ``build hook'' of the daemon
3931 (@pxref{Daemon Offload Setup}). That is, always build things locally
3932 instead of offloading builds to remote machines.
3934 @item --max-silent-time=@var{seconds}
3935 When the build or substitution process remains silent for more than
3936 @var{seconds}, terminate it and report a build failure.
3938 @item --timeout=@var{seconds}
3939 Likewise, when the build or substitution process lasts for more than
3940 @var{seconds}, terminate it and report a build failure.
3942 By default there is no timeout. This behavior can be restored with
3945 @item --verbosity=@var{level}
3946 Use the given verbosity level. @var{level} must be an integer between 0
3947 and 5; higher means more verbose output. Setting a level of 4 or more
3948 may be helpful when debugging setup issues with the build daemon.
3950 @item --cores=@var{n}
3952 Allow the use of up to @var{n} CPU cores for the build. The special
3953 value @code{0} means to use as many CPU cores as available.
3955 @item --max-jobs=@var{n}
3957 Allow at most @var{n} build jobs in parallel. @xref{Invoking
3958 guix-daemon, @code{--max-jobs}}, for details about this option and the
3959 equivalent @command{guix-daemon} option.
3963 Behind the scenes, @command{guix build} is essentially an interface to
3964 the @code{package-derivation} procedure of the @code{(guix packages)}
3965 module, and to the @code{build-derivations} procedure of the @code{(guix
3966 derivations)} module.
3968 In addition to options explicitly passed on the command line,
3969 @command{guix build} and other @command{guix} commands that support
3970 building honor the @code{GUIX_BUILD_OPTIONS} environment variable.
3972 @defvr {Environment Variable} GUIX_BUILD_OPTIONS
3973 Users can define this variable to a list of command line options that
3974 will automatically be used by @command{guix build} and other
3975 @command{guix} commands that can perform builds, as in the example
3979 $ export GUIX_BUILD_OPTIONS="--no-substitutes -c 2 -L /foo/bar"
3982 These options are parsed independently, and the result is appended to
3983 the parsed command-line options.
3987 @node Package Transformation Options
3988 @subsection Package Transformation Options
3990 @cindex package variants
3991 Another set of command-line options supported by @command{guix build}
3992 and also @command{guix package} are @dfn{package transformation
3993 options}. These are options that make it possible to define @dfn{package
3994 variants}---for instance, packages built from different source code.
3995 This is a convenient way to create customized packages on the fly
3996 without having to type in the definitions of package variants
3997 (@pxref{Defining Packages}).
4001 @item --with-source=@var{source}
4002 Use @var{source} as the source of the corresponding package.
4003 @var{source} must be a file name or a URL, as for @command{guix
4004 download} (@pxref{Invoking guix download}).
4006 The ``corresponding package'' is taken to be the one specified on the
4007 command line the name of which matches the base of @var{source}---e.g.,
4008 if @var{source} is @code{/src/guile-2.0.10.tar.gz}, the corresponding
4009 package is @code{guile}. Likewise, the version string is inferred from
4010 @var{source}; in the previous example, it is @code{2.0.10}.
4012 This option allows users to try out versions of packages other than the
4013 one provided by the distribution. The example below downloads
4014 @file{ed-1.7.tar.gz} from a GNU mirror and uses that as the source for
4015 the @code{ed} package:
4018 guix build ed --with-source=mirror://gnu/ed/ed-1.7.tar.gz
4021 As a developer, @code{--with-source} makes it easy to test release
4025 guix build guile --with-source=../guile-2.0.9.219-e1bb7.tar.xz
4028 @dots{} or to build from a checkout in a pristine environment:
4031 $ git clone git://git.sv.gnu.org/guix.git
4032 $ guix build guix --with-source=./guix
4035 @item --with-input=@var{package}=@var{replacement}
4036 Replace dependency on @var{package} by a dependency on
4037 @var{replacement}. @var{package} must be a package name, and
4038 @var{replacement} must be a package specification such as @code{guile}
4039 or @code{guile@@1.8}.
4041 For instance, the following command builds Guix, but replaces its
4042 dependency on the current stable version of Guile with a dependency on
4043 the development version of Guile, @code{guile-next}:
4046 guix build --with-input=guile=guile-next guix
4049 This is a recursive, deep replacement. So in this example, both
4050 @code{guix} and its dependency @code{guile-json} (which also depends on
4051 @code{guile}) get rebuilt against @code{guile-next}.
4053 However, implicit inputs are left unchanged.
4056 @node Additional Build Options
4057 @subsection Additional Build Options
4059 The command-line options presented below are specific to @command{guix
4064 @item --file=@var{file}
4065 @itemx -f @var{file}
4067 Build the package or derivation that the code within @var{file}
4070 As an example, @var{file} might contain a package definition like this
4071 (@pxref{Defining Packages}):
4074 @verbatiminclude package-hello.scm
4077 @item --expression=@var{expr}
4078 @itemx -e @var{expr}
4079 Build the package or derivation @var{expr} evaluates to.
4081 For example, @var{expr} may be @code{(@@ (gnu packages guile)
4082 guile-1.8)}, which unambiguously designates this specific variant of
4083 version 1.8 of Guile.
4085 Alternatively, @var{expr} may be a G-expression, in which case it is used
4086 as a build program passed to @code{gexp->derivation}
4087 (@pxref{G-Expressions}).
4089 Lastly, @var{expr} may refer to a zero-argument monadic procedure
4090 (@pxref{The Store Monad}). The procedure must return a derivation as a
4091 monadic value, which is then passed through @code{run-with-store}.
4095 Build the source derivations of the packages, rather than the packages
4098 For instance, @code{guix build -S gcc} returns something like
4099 @file{/gnu/store/@dots{}-gcc-4.7.2.tar.bz2}, which is the GCC
4102 The returned source tarball is the result of applying any patches and
4103 code snippets specified in the package @code{origin} (@pxref{Defining
4107 Fetch and return the source of @var{package-or-derivation} and all their
4108 dependencies, recursively. This is a handy way to obtain a local copy
4109 of all the source code needed to build @var{packages}, allowing you to
4110 eventually build them even without network access. It is an extension
4111 of the @code{--source} option and can accept one of the following
4112 optional argument values:
4116 This value causes the @code{--sources} option to behave in the same way
4117 as the @code{--source} option.
4120 Build the source derivations of all packages, including any source that
4121 might be listed as @code{inputs}. This is the default value.
4124 $ guix build --sources tzdata
4125 The following derivations will be built:
4126 /gnu/store/@dots{}-tzdata2015b.tar.gz.drv
4127 /gnu/store/@dots{}-tzcode2015b.tar.gz.drv
4131 Build the source derivations of all packages, as well of all transitive
4132 inputs to the packages. This can be used e.g. to
4133 prefetch package source for later offline building.
4136 $ guix build --sources=transitive tzdata
4137 The following derivations will be built:
4138 /gnu/store/@dots{}-tzcode2015b.tar.gz.drv
4139 /gnu/store/@dots{}-findutils-4.4.2.tar.xz.drv
4140 /gnu/store/@dots{}-grep-2.21.tar.xz.drv
4141 /gnu/store/@dots{}-coreutils-8.23.tar.xz.drv
4142 /gnu/store/@dots{}-make-4.1.tar.xz.drv
4143 /gnu/store/@dots{}-bash-4.3.tar.xz.drv
4149 @item --system=@var{system}
4150 @itemx -s @var{system}
4151 Attempt to build for @var{system}---e.g., @code{i686-linux}---instead of
4152 the system type of the build host.
4154 An example use of this is on Linux-based systems, which can emulate
4155 different personalities. For instance, passing
4156 @code{--system=i686-linux} on an @code{x86_64-linux} system allows users
4157 to build packages in a complete 32-bit environment.
4159 @item --target=@var{triplet}
4160 @cindex cross-compilation
4161 Cross-build for @var{triplet}, which must be a valid GNU triplet, such
4162 as @code{"mips64el-linux-gnu"} (@pxref{Configuration Names, GNU
4163 configuration triplets,, configure, GNU Configure and Build System}).
4165 @anchor{build-check}
4167 @cindex determinism, checking
4168 @cindex reproducibility, checking
4169 Rebuild @var{package-or-derivation}, which are already available in the
4170 store, and raise an error if the build results are not bit-for-bit
4173 This mechanism allows you to check whether previously installed
4174 substitutes are genuine (@pxref{Substitutes}), or whether the build result
4175 of a package is deterministic. @xref{Invoking guix challenge}, for more
4176 background information and tools.
4179 Do not ``graft'' packages. In practice, this means that package updates
4180 available as grafts are not applied. @xref{Security Updates}, for more
4181 information on grafts.
4185 Return the derivation paths, not the output paths, of the given
4188 @item --root=@var{file}
4189 @itemx -r @var{file}
4190 Make @var{file} a symlink to the result, and register it as a garbage
4194 Return the build log file names or URLs for the given
4195 @var{package-or-derivation}, or raise an error if build logs are
4198 This works regardless of how packages or derivations are specified. For
4199 instance, the following invocations are equivalent:
4202 guix build --log-file `guix build -d guile`
4203 guix build --log-file `guix build guile`
4204 guix build --log-file guile
4205 guix build --log-file -e '(@@ (gnu packages guile) guile-2.0)'
4208 If a log is unavailable locally, and unless @code{--no-substitutes} is
4209 passed, the command looks for a corresponding log on one of the
4210 substitute servers (as specified with @code{--substitute-urls}.)
4212 So for instance, imagine you want to see the build log of GDB on MIPS,
4213 but you are actually on an @code{x86_64} machine:
4216 $ guix build --log-file gdb -s mips64el-linux
4217 http://hydra.gnu.org/log/@dots{}-gdb-7.10
4220 You can freely access a huge library of build logs!
4224 @node Invoking guix edit
4225 @section Invoking @command{guix edit}
4227 @cindex package definition, editing
4228 So many packages, so many source files! The @command{guix edit} command
4229 facilitates the life of packagers by pointing their editor at the source
4230 file containing the definition of the specified packages. For instance:
4233 guix edit gcc-4.8 vim
4237 launches the program specified in the @code{VISUAL} or in the
4238 @code{EDITOR} environment variable to edit the recipe of GCC@tie{}4.8.4
4241 If you are using Emacs, note that the Emacs user interface provides the
4242 @kbd{M-x guix-edit} command and a similar functionality in the ``package
4243 info'' and ``package list'' buffers created by the @kbd{M-x
4244 guix-search-by-name} and similar commands (@pxref{Emacs Commands}).
4247 @node Invoking guix download
4248 @section Invoking @command{guix download}
4250 When writing a package definition, developers typically need to download
4251 a source tarball, compute its SHA256 hash, and write that
4252 hash in the package definition (@pxref{Defining Packages}). The
4253 @command{guix download} tool helps with this task: it downloads a file
4254 from the given URI, adds it to the store, and prints both its file name
4255 in the store and its SHA256 hash.
4257 The fact that the downloaded file is added to the store saves bandwidth:
4258 when the developer eventually tries to build the newly defined package
4259 with @command{guix build}, the source tarball will not have to be
4260 downloaded again because it is already in the store. It is also a
4261 convenient way to temporarily stash files, which may be deleted
4262 eventually (@pxref{Invoking guix gc}).
4264 The @command{guix download} command supports the same URIs as used in
4265 package definitions. In particular, it supports @code{mirror://} URIs.
4266 @code{https} URIs (HTTP over TLS) are supported @emph{provided} the
4267 Guile bindings for GnuTLS are available in the user's environment; when
4268 they are not available, an error is raised. @xref{Guile Preparations,
4269 how to install the GnuTLS bindings for Guile,, gnutls-guile,
4270 GnuTLS-Guile}, for more information.
4272 The following option is available:
4275 @item --format=@var{fmt}
4277 Write the hash in the format specified by @var{fmt}. For more
4278 information on the valid values for @var{fmt}, @pxref{Invoking guix hash}.
4281 @node Invoking guix hash
4282 @section Invoking @command{guix hash}
4284 The @command{guix hash} command computes the SHA256 hash of a file.
4285 It is primarily a convenience tool for anyone contributing to the
4286 distribution: it computes the cryptographic hash of a file, which can be
4287 used in the definition of a package (@pxref{Defining Packages}).
4289 The general syntax is:
4292 guix hash @var{option} @var{file}
4295 @command{guix hash} has the following option:
4299 @item --format=@var{fmt}
4301 Write the hash in the format specified by @var{fmt}.
4303 Supported formats: @code{nix-base32}, @code{base32}, @code{base16}
4304 (@code{hex} and @code{hexadecimal} can be used as well).
4306 If the @option{--format} option is not specified, @command{guix hash}
4307 will output the hash in @code{nix-base32}. This representation is used
4308 in the definitions of packages.
4312 Compute the hash on @var{file} recursively.
4314 In this case, the hash is computed on an archive containing @var{file},
4315 including its children if it is a directory. Some of the metadata of
4316 @var{file} is part of the archive; for instance, when @var{file} is a
4317 regular file, the hash is different depending on whether @var{file} is
4318 executable or not. Metadata such as time stamps has no impact on the
4319 hash (@pxref{Invoking guix archive}).
4320 @c FIXME: Replace xref above with xref to an ``Archive'' section when
4325 @node Invoking guix import
4326 @section Invoking @command{guix import}
4328 @cindex importing packages
4329 @cindex package import
4330 @cindex package conversion
4331 The @command{guix import} command is useful for people who would like to
4332 add a package to the distribution with as little work as
4333 possible---a legitimate demand. The command knows of a few
4334 repositories from which it can ``import'' package metadata. The result
4335 is a package definition, or a template thereof, in the format we know
4336 (@pxref{Defining Packages}).
4338 The general syntax is:
4341 guix import @var{importer} @var{options}@dots{}
4344 @var{importer} specifies the source from which to import package
4345 metadata, and @var{options} specifies a package identifier and other
4346 options specific to @var{importer}. Currently, the available
4351 Import metadata for the given GNU package. This provides a template
4352 for the latest version of that GNU package, including the hash of its
4353 source tarball, and its canonical synopsis and description.
4355 Additional information such as the package dependencies and its
4356 license needs to be figured out manually.
4358 For example, the following command returns a package definition for
4362 guix import gnu hello
4365 Specific command-line options are:
4368 @item --key-download=@var{policy}
4369 As for @code{guix refresh}, specify the policy to handle missing OpenPGP
4370 keys when verifying the package signature. @xref{Invoking guix
4371 refresh, @code{--key-download}}.
4376 Import metadata from the @uref{https://pypi.python.org/, Python Package
4377 Index}@footnote{This functionality requires Guile-JSON to be installed.
4378 @xref{Requirements}.}. Information is taken from the JSON-formatted
4379 description available at @code{pypi.python.org} and usually includes all
4380 the relevant information, including package dependencies.
4382 The command below imports metadata for the @code{itsdangerous} Python
4386 guix import pypi itsdangerous
4391 Import metadata from @uref{https://rubygems.org/,
4392 RubyGems}@footnote{This functionality requires Guile-JSON to be
4393 installed. @xref{Requirements}.}. Information is taken from the
4394 JSON-formatted description available at @code{rubygems.org} and includes
4395 most relevant information, including runtime dependencies. There are
4396 some caveats, however. The metadata doesn't distinguish between
4397 synopses and descriptions, so the same string is used for both fields.
4398 Additionally, the details of non-Ruby dependencies required to build
4399 native extensions is unavailable and left as an exercise to the
4402 The command below imports metadata for the @code{rails} Ruby package:
4405 guix import gem rails
4410 Import metadata from @uref{https://www.metacpan.org/, MetaCPAN}@footnote{This
4411 functionality requires Guile-JSON to be installed.
4412 @xref{Requirements}.}.
4413 Information is taken from the JSON-formatted metadata provided through
4414 @uref{https://api.metacpan.org/, MetaCPAN's API} and includes most
4415 relevant information, such as module dependencies. License information
4416 should be checked closely. If Perl is available in the store, then the
4417 @code{corelist} utility will be used to filter core modules out of the
4418 list of dependencies.
4420 The command command below imports metadata for the @code{Acme::Boolean}
4424 guix import cpan Acme::Boolean
4429 @cindex Bioconductor
4430 Import metadata from @uref{http://cran.r-project.org/, CRAN}, the
4431 central repository for the @uref{http://r-project.org, GNU@tie{}R
4432 statistical and graphical environment}.
4434 Information is extracted from the @code{DESCRIPTION} file of the package.
4436 The command command below imports metadata for the @code{Cairo}
4440 guix import cran Cairo
4443 When @code{--archive=bioconductor} is added, metadata is imported from
4444 @uref{http://www.bioconductor.org/, Bioconductor}, a repository of R
4445 packages for for the analysis and comprehension of high-throughput
4446 genomic data in bioinformatics.
4448 Information is extracted from the @code{DESCRIPTION} file of a package
4449 published on the web interface of the Bioconductor SVN repository.
4451 The command below imports metadata for the @code{GenomicRanges}
4455 guix import cran --archive=bioconductor GenomicRanges
4459 Import metadata from a local copy of the source of the
4460 @uref{http://nixos.org/nixpkgs/, Nixpkgs distribution}@footnote{This
4461 relies on the @command{nix-instantiate} command of
4462 @uref{http://nixos.org/nix/, Nix}.}. Package definitions in Nixpkgs are
4463 typically written in a mixture of Nix-language and Bash code. This
4464 command only imports the high-level package structure that is written in
4465 the Nix language. It normally includes all the basic fields of a
4468 When importing a GNU package, the synopsis and descriptions are replaced
4469 by their canonical upstream variant.
4471 Usually, you will first need to do:
4474 export NIX_REMOTE=daemon
4478 so that @command{nix-instantiate} does not try to open the Nix database.
4480 As an example, the command below imports the package definition of
4481 LibreOffice (more precisely, it imports the definition of the package
4482 bound to the @code{libreoffice} top-level attribute):
4485 guix import nix ~/path/to/nixpkgs libreoffice
4490 Import metadata from the Haskell community's central package archive
4491 @uref{https://hackage.haskell.org/, Hackage}. Information is taken from
4492 Cabal files and includes all the relevant information, including package
4495 Specific command-line options are:
4500 Read a Cabal file from standard input.
4501 @item --no-test-dependencies
4503 Do not include dependencies required only by the test suites.
4504 @item --cabal-environment=@var{alist}
4505 @itemx -e @var{alist}
4506 @var{alist} is a Scheme alist defining the environment in which the
4507 Cabal conditionals are evaluated. The accepted keys are: @code{os},
4508 @code{arch}, @code{impl} and a string representing the name of a flag.
4509 The value associated with a flag has to be either the symbol
4510 @code{true} or @code{false}. The value associated with other keys
4511 has to conform to the Cabal file format definition. The default value
4512 associated with the keys @code{os}, @code{arch} and @code{impl} is
4513 @samp{linux}, @samp{x86_64} and @samp{ghc}, respectively.
4516 The command below imports metadata for the latest version of the
4517 @code{HTTP} Haskell package without including test dependencies and
4518 specifying the value of the flag @samp{network-uri} as @code{false}:
4521 guix import hackage -t -e "'((\"network-uri\" . false))" HTTP
4524 A specific package version may optionally be specified by following the
4525 package name by a hyphen and a version number as in the following example:
4528 guix import hackage mtl-2.1.3.1
4533 Import metadata from an Emacs Lisp Package Archive (ELPA) package
4534 repository (@pxref{Packages,,, emacs, The GNU Emacs Manual}).
4536 Specific command-line options are:
4539 @item --archive=@var{repo}
4540 @itemx -a @var{repo}
4541 @var{repo} identifies the archive repository from which to retrieve the
4542 information. Currently the supported repositories and their identifiers
4546 @uref{http://elpa.gnu.org/packages, GNU}, selected by the @code{gnu}
4547 identifier. This is the default.
4550 @uref{http://stable.melpa.org/packages, MELPA-Stable}, selected by the
4551 @code{melpa-stable} identifier.
4554 @uref{http://melpa.org/packages, MELPA}, selected by the @code{melpa}
4560 The structure of the @command{guix import} code is modular. It would be
4561 useful to have more importers for other package formats, and your help
4562 is welcome here (@pxref{Contributing}).
4564 @node Invoking guix refresh
4565 @section Invoking @command{guix refresh}
4567 The primary audience of the @command{guix refresh} command is developers
4568 of the GNU software distribution. By default, it reports any packages
4569 provided by the distribution that are outdated compared to the latest
4570 upstream version, like this:
4574 gnu/packages/gettext.scm:29:13: gettext would be upgraded from 0.18.1.1 to 0.18.2.1
4575 gnu/packages/glib.scm:77:12: glib would be upgraded from 2.34.3 to 2.37.0
4578 It does so by browsing the FTP directory of each package and determining
4579 the highest version number of the source tarballs therein. The command
4580 knows how to update specific types of packages: GNU packages, ELPA
4581 packages, etc.---see the documentation for @option{--type} below. The
4582 are many packages, though, for which it lacks a method to determine
4583 whether a new upstream release is available. However, the mechanism is
4584 extensible, so feel free to get in touch with us to add a new method!
4586 When passed @code{--update}, it modifies distribution source files to
4587 update the version numbers and source tarball hashes of those package
4588 recipes (@pxref{Defining Packages}). This is achieved by downloading
4589 each package's latest source tarball and its associated OpenPGP
4590 signature, authenticating the downloaded tarball against its signature
4591 using @command{gpg}, and finally computing its hash. When the public
4592 key used to sign the tarball is missing from the user's keyring, an
4593 attempt is made to automatically retrieve it from a public key server;
4594 when this is successful, the key is added to the user's keyring; otherwise,
4595 @command{guix refresh} reports an error.
4597 The following options are supported:
4601 @item --expression=@var{expr}
4602 @itemx -e @var{expr}
4603 Consider the package @var{expr} evaluates to.
4605 This is useful to precisely refer to a package, as in this example:
4608 guix refresh -l -e '(@@@@ (gnu packages commencement) glibc-final)'
4611 This command lists the dependents of the ``final'' libc (essentially all
4616 Update distribution source files (package recipes) in place. This is
4617 usually run from a checkout of the Guix source tree (@pxref{Running
4618 Guix Before It Is Installed}):
4621 $ ./pre-inst-env guix refresh -s non-core
4624 @xref{Defining Packages}, for more information on package definitions.
4626 @item --select=[@var{subset}]
4627 @itemx -s @var{subset}
4628 Select all the packages in @var{subset}, one of @code{core} or
4631 The @code{core} subset refers to all the packages at the core of the
4632 distribution---i.e., packages that are used to build ``everything
4633 else''. This includes GCC, libc, Binutils, Bash, etc. Usually,
4634 changing one of these packages in the distribution entails a rebuild of
4635 all the others. Thus, such updates are an inconvenience to users in
4636 terms of build time or bandwidth used to achieve the upgrade.
4638 The @code{non-core} subset refers to the remaining packages. It is
4639 typically useful in cases where an update of the core packages would be
4642 @item --type=@var{updater}
4643 @itemx -t @var{updater}
4644 Select only packages handled by @var{updater} (may be a comma-separated
4645 list of updaters). Currently, @var{updater} may be one of:
4649 the updater for GNU packages;
4651 the updater for GNOME packages;
4653 the updater for X.org packages;
4655 the updater for @uref{http://elpa.gnu.org/, ELPA} packages;
4657 the updater for @uref{http://cran.r-project.org/, CRAN} packages;
4659 the updater for @uref{http://www.bioconductor.org/, Bioconductor} R packages;
4661 the updater for @uref{https://pypi.python.org, PyPI} packages.
4663 the updater for @uref{https://rubygems.org, RubyGems} packages.
4665 the updater for @uref{https://github.com, GitHub} packages.
4668 For instance, the following command only checks for updates of Emacs
4669 packages hosted at @code{elpa.gnu.org} and for updates of CRAN packages:
4672 $ guix refresh --type=elpa,cran
4673 gnu/packages/statistics.scm:819:13: r-testthat would be upgraded from 0.10.0 to 0.11.0
4674 gnu/packages/emacs.scm:856:13: emacs-auctex would be upgraded from 11.88.6 to 11.88.9
4679 In addition, @command{guix refresh} can be passed one or more package
4680 names, as in this example:
4683 $ ./pre-inst-env guix refresh -u emacs idutils gcc-4.8.4
4687 The command above specifically updates the @code{emacs} and
4688 @code{idutils} packages. The @code{--select} option would have no
4689 effect in this case.
4691 When considering whether to upgrade a package, it is sometimes
4692 convenient to know which packages would be affected by the upgrade and
4693 should be checked for compatibility. For this the following option may
4694 be used when passing @command{guix refresh} one or more package names:
4698 @item --list-updaters
4700 List available updaters and exit (see @option{--type} above.)
4702 @item --list-dependent
4704 List top-level dependent packages that would need to be rebuilt as a
4705 result of upgrading one or more packages.
4709 Be aware that the @code{--list-dependent} option only
4710 @emph{approximates} the rebuilds that would be required as a result of
4711 an upgrade. More rebuilds might be required under some circumstances.
4714 $ guix refresh --list-dependent flex
4715 Building the following 120 packages would ensure 213 dependent packages are rebuilt:
4716 hop-2.4.0 geiser-0.4 notmuch-0.18 mu-0.9.9.5 cflow-1.4 idutils-4.6 @dots{}
4719 The command above lists a set of packages that could be built to check
4720 for compatibility with an upgraded @code{flex} package.
4722 The following options can be used to customize GnuPG operation:
4726 @item --gpg=@var{command}
4727 Use @var{command} as the GnuPG 2.x command. @var{command} is searched
4728 for in @code{$PATH}.
4730 @item --key-download=@var{policy}
4731 Handle missing OpenPGP keys according to @var{policy}, which may be one
4736 Always download missing OpenPGP keys from the key server, and add them
4737 to the user's GnuPG keyring.
4740 Never try to download missing OpenPGP keys. Instead just bail out.
4743 When a package signed with an unknown OpenPGP key is encountered, ask
4744 the user whether to download it or not. This is the default behavior.
4747 @item --key-server=@var{host}
4748 Use @var{host} as the OpenPGP key server when importing a public key.
4752 The @code{github} updater uses the
4753 @uref{https://developer.github.com/v3/, GitHub API} to query for new
4754 releases. When used repeatedly e.g. when refreshing all packages,
4755 GitHub will eventually refuse to answer any further API requests. By
4756 default 60 API requests per hour are allowed, and a full refresh on all
4757 GitHub packages in Guix requires more than this. Authentication with
4758 GitHub through the use of an API token alleviates these limits. To use
4759 an API token, set the environment variable @code{GUIX_GITHUB_TOKEN} to a
4760 token procured from @uref{https://github.com/settings/tokens} or
4764 @node Invoking guix lint
4765 @section Invoking @command{guix lint}
4766 The @command{guix lint} command is meant to help package developers avoid
4767 common errors and use a consistent style. It runs a number of checks on
4768 a given set of packages in order to find common mistakes in their
4769 definitions. Available @dfn{checkers} include (see
4770 @code{--list-checkers} for a complete list):
4775 Validate certain typographical and stylistic rules about package
4776 descriptions and synopses.
4778 @item inputs-should-be-native
4779 Identify inputs that should most likely be native inputs.
4783 @itemx source-file-name
4784 Probe @code{home-page} and @code{source} URLs and report those that are
4785 invalid. Check that the source file name is meaningful, e.g. is not
4786 just a version number or ``git-checkout'', without a declared
4787 @code{file-name} (@pxref{origin Reference}).
4790 Report known vulnerabilities found in the Common Vulnerabilities and
4791 Exposures (CVE) database
4792 @uref{https://nvd.nist.gov/download.cfm#CVE_FEED, published by the US
4796 Warn about obvious source code formatting issues: trailing white space,
4797 use of tabulations, etc.
4800 The general syntax is:
4803 guix lint @var{options} @var{package}@dots{}
4806 If no package is given on the command line, then all packages are checked.
4807 The @var{options} may be zero or more of the following:
4810 @item --list-checkers
4812 List and describe all the available checkers that will be run on packages
4817 Only enable the checkers specified in a comma-separated list using the
4818 names returned by @code{--list-checkers}.
4822 @node Invoking guix size
4823 @section Invoking @command{guix size}
4825 The @command{guix size} command helps package developers profile the
4826 disk usage of packages. It is easy to overlook the impact of an
4827 additional dependency added to a package, or the impact of using a
4828 single output for a package that could easily be split (@pxref{Packages
4829 with Multiple Outputs}). Such are the typical issues that
4830 @command{guix size} can highlight.
4832 The command can be passed a package specification such as @code{gcc-4.8}
4833 or @code{guile:debug}, or a file name in the store. Consider this
4837 $ guix size coreutils
4838 store item total self
4839 /gnu/store/@dots{}-coreutils-8.23 70.0 13.9 19.8%
4840 /gnu/store/@dots{}-gmp-6.0.0a 55.3 2.5 3.6%
4841 /gnu/store/@dots{}-acl-2.2.52 53.7 0.5 0.7%
4842 /gnu/store/@dots{}-attr-2.4.46 53.2 0.3 0.5%
4843 /gnu/store/@dots{}-gcc-4.8.4-lib 52.9 15.7 22.4%
4844 /gnu/store/@dots{}-glibc-2.21 37.2 37.2 53.1%
4848 The store items listed here constitute the @dfn{transitive closure} of
4849 Coreutils---i.e., Coreutils and all its dependencies, recursively---as
4850 would be returned by:
4853 $ guix gc -R /gnu/store/@dots{}-coreutils-8.23
4856 Here the output shows three columns next to store items. The first column,
4857 labeled ``total'', shows the size in mebibytes (MiB) of the closure of
4858 the store item---that is, its own size plus the size of all its
4859 dependencies. The next column, labeled ``self'', shows the size of the
4860 item itself. The last column shows the ratio of the size of the item
4861 itself to the space occupied by all the items listed here.
4863 In this example, we see that the closure of Coreutils weighs in at
4864 70@tie{}MiB, half of which is taken by libc. (That libc represents a
4865 large fraction of the closure is not a problem @i{per se} because it is
4866 always available on the system anyway.)
4868 When the package passed to @command{guix size} is available in the
4869 store, @command{guix size} queries the daemon to determine its
4870 dependencies, and measures its size in the store, similar to @command{du
4871 -ms --apparent-size} (@pxref{du invocation,,, coreutils, GNU
4874 When the given package is @emph{not} in the store, @command{guix size}
4875 reports information based on the available substitutes
4876 (@pxref{Substitutes}). This makes it possible it to profile disk usage of
4877 store items that are not even on disk, only available remotely.
4879 The available options are:
4883 @item --substitute-urls=@var{urls}
4884 Use substitute information from @var{urls}.
4885 @xref{client-substitute-urls, the same option for @code{guix build}}.
4887 @item --map-file=@var{file}
4888 Write a graphical map of disk usage in PNG format to @var{file}.
4890 For the example above, the map looks like this:
4892 @image{images/coreutils-size-map,5in,, map of Coreutils disk usage
4893 produced by @command{guix size}}
4895 This option requires that
4896 @uref{http://wingolog.org/software/guile-charting/, Guile-Charting} be
4897 installed and visible in Guile's module search path. When that is not
4898 the case, @command{guix size} fails as it tries to load it.
4900 @item --system=@var{system}
4901 @itemx -s @var{system}
4902 Consider packages for @var{system}---e.g., @code{x86_64-linux}.
4906 @node Invoking guix graph
4907 @section Invoking @command{guix graph}
4910 Packages and their dependencies form a @dfn{graph}, specifically a
4911 directed acyclic graph (DAG). It can quickly become difficult to have a
4912 mental model of the package DAG, so the @command{guix graph} command
4913 provides a visual representation of the DAG. @command{guix graph}
4914 emits a DAG representation in the input format of
4915 @uref{http://www.graphviz.org/, Graphviz}, so its output can be passed
4916 directly to the @command{dot} command of Graphviz. The general
4920 guix graph @var{options} @var{package}@dots{}
4923 For example, the following command generates a PDF file representing the
4924 package DAG for the GNU@tie{}Core Utilities, showing its build-time
4928 guix graph coreutils | dot -Tpdf > dag.pdf
4931 The output looks like this:
4933 @image{images/coreutils-graph,2in,,Dependency graph of the GNU Coreutils}
4935 Nice little graph, no?
4937 But there is more than one graph! The one above is concise: it is the
4938 graph of package objects, omitting implicit inputs such as GCC, libc,
4939 grep, etc. It is often useful to have such a concise graph, but
4940 sometimes one may want to see more details. @command{guix graph} supports
4941 several types of graphs, allowing you to choose the level of detail:
4945 This is the default type used in the example above. It shows the DAG of
4946 package objects, excluding implicit dependencies. It is concise, but
4947 filters out many details.
4950 This is the package DAG, @emph{including} implicit inputs.
4952 For instance, the following command:
4955 guix graph --type=bag-emerged coreutils | dot -Tpdf > dag.pdf
4958 ... yields this bigger graph:
4960 @image{images/coreutils-bag-graph,,5in,Detailed dependency graph of the GNU Coreutils}
4962 At the bottom of the graph, we see all the implicit inputs of
4963 @var{gnu-build-system} (@pxref{Build Systems, @code{gnu-build-system}}).
4965 Now, note that the dependencies of these implicit inputs---that is, the
4966 @dfn{bootstrap dependencies} (@pxref{Bootstrapping})---are not shown
4967 here, for conciseness.
4970 Similar to @code{bag-emerged}, but this time including all the bootstrap
4973 @item bag-with-origins
4974 Similar to @code{bag}, but also showing origins and their dependencies.
4977 This is the most detailed representation: It shows the DAG of
4978 derivations (@pxref{Derivations}) and plain store items. Compared to
4979 the above representation, many additional nodes are visible, including
4980 build scripts, patches, Guile modules, etc.
4984 All the types above correspond to @emph{build-time dependencies}. The
4985 following graph type represents the @emph{run-time dependencies}:
4989 This is the graph of @dfn{references} of a package output, as returned
4990 by @command{guix gc --references} (@pxref{Invoking guix gc}).
4992 If the given package output is not available in the store, @command{guix
4993 graph} attempts to obtain dependency information from substitutes.
4996 The available options are the following:
4999 @item --type=@var{type}
5000 @itemx -t @var{type}
5001 Produce a graph output of @var{type}, where @var{type} must be one of
5002 the values listed above.
5005 List the supported graph types.
5007 @item --expression=@var{expr}
5008 @itemx -e @var{expr}
5009 Consider the package @var{expr} evaluates to.
5011 This is useful to precisely refer to a package, as in this example:
5014 guix graph -e '(@@@@ (gnu packages commencement) gnu-make-final)'
5019 @node Invoking guix environment
5020 @section Invoking @command{guix environment}
5022 @cindex reproducible build environments
5023 @cindex development environments
5024 The purpose of @command{guix environment} is to assist hackers in
5025 creating reproducible development environments without polluting their
5026 package profile. The @command{guix environment} tool takes one or more
5027 packages, builds all of their inputs, and creates a shell
5028 environment to use them.
5030 The general syntax is:
5033 guix environment @var{options} @var{package}@dots{}
5036 The following example spawns a new shell set up for the development of
5040 guix environment guile
5043 If the needed dependencies are not built yet, @command{guix environment}
5044 automatically builds them. The environment of the new shell is an augmented
5045 version of the environment that @command{guix environment} was run in.
5046 It contains the necessary search paths for building the given package
5047 added to the existing environment variables. To create a ``pure''
5048 environment, in which the original environment variables have been unset,
5049 use the @code{--pure} option@footnote{Users sometimes wrongfully augment
5050 environment variables such as @code{PATH} in their @file{~/.bashrc}
5051 file. As a consequence, when @code{guix environment} launches it, Bash
5052 may read @file{~/.bashrc}, thereby introducing ``impurities'' in these
5053 environment variables. It is an error to define such environment
5054 variables in @file{.bashrc}; instead, they should be defined in
5055 @file{.bash_profile}, which is sourced only by log-in shells.
5056 @xref{Bash Startup Files,,, bash, The GNU Bash Reference Manual}, for
5057 details on Bash start-up files.}.
5059 @vindex GUIX_ENVIRONMENT
5060 @command{guix environment} defines the @code{GUIX_ENVIRONMENT}
5061 variable in the shell it spawns. This allows users to, say, define a
5062 specific prompt for development environments in their @file{.bashrc}
5063 (@pxref{Bash Startup Files,,, bash, The GNU Bash Reference Manual}):
5066 if [ -n "$GUIX_ENVIRONMENT" ]
5068 export PS1="\u@@\h \w [dev]\$ "
5072 Additionally, more than one package may be specified, in which case the
5073 union of the inputs for the given packages are used. For example, the
5074 command below spawns a shell where all of the dependencies of both Guile
5075 and Emacs are available:
5078 guix environment guile emacs
5081 Sometimes an interactive shell session is not desired. An arbitrary
5082 command may be invoked by placing the @code{--} token to separate the
5083 command from the rest of the arguments:
5086 guix environment guile -- make -j4
5089 In other situations, it is more convenient to specify the list of
5090 packages needed in the environment. For example, the following command
5091 runs @command{python} from an environment containing Python@tie{}2.7 and
5095 guix environment --ad-hoc python2-numpy python-2.7 -- python
5098 Furthermore, one might want the dependencies of a package and also some
5099 additional packages that are not build-time or runtime dependencies, but
5100 are useful when developing nonetheless. Because of this, the
5101 @code{--ad-hoc} flag is positional. Packages appearing before
5102 @code{--ad-hoc} are interpreted as packages whose dependencies will be
5103 added to the environment. Packages appearing after are interpreted as
5104 packages that will be added to the environment directly. For example,
5105 the following command creates a Guix development environment that
5106 additionally includes Git and strace:
5109 guix environment guix --ad-hoc git strace
5112 Sometimes it is desirable to isolate the environment as much as
5113 possible, for maximal purity and reproducibility. In particular, when
5114 using Guix on a host distro that is not GuixSD, it is desirable to
5115 prevent access to @file{/usr/bin} and other system-wide resources from
5116 the development environment. For example, the following command spawns
5117 a Guile REPL in a ``container'' where only the store and the current
5118 working directory are mounted:
5121 guix environment --ad-hoc --container guile -- guile
5125 The @code{--container} option requires Linux-libre 3.19 or newer.
5128 The available options are summarized below.
5131 @item --expression=@var{expr}
5132 @itemx -e @var{expr}
5133 Create an environment for the package or list of packages that
5134 @var{expr} evaluates to.
5136 For example, running:
5139 guix environment -e '(@@ (gnu packages maths) petsc-openmpi)'
5142 starts a shell with the environment for this specific variant of the
5148 guix environment --ad-hoc -e '(@@ (gnu) %base-packages)'
5151 starts a shell with all the GuixSD base packages available.
5153 The above commands only the use default output of the given packages.
5154 To select other outputs, two element tuples can be specified:
5157 guix environment --ad-hoc -e '(list (@ (gnu packages bash) bash) "include")'
5160 @item --load=@var{file}
5161 @itemx -l @var{file}
5162 Create an environment for the package or list of packages that the code
5163 within @var{file} evaluates to.
5165 As an example, @var{file} might contain a definition like this
5166 (@pxref{Defining Packages}):
5169 @verbatiminclude environment-gdb.scm
5173 Include all specified packages in the resulting environment, as if an
5174 @i{ad hoc} package were defined with them as inputs. This option is
5175 useful for quickly creating an environment without having to write a
5176 package expression to contain the desired inputs.
5178 For instance, the command:
5181 guix environment --ad-hoc guile guile-sdl -- guile
5184 runs @command{guile} in an environment where Guile and Guile-SDL are
5187 Note that this example implicitly asks for the default output of
5188 @code{guile} and @code{guile-sdl}, but it is possible to ask for a
5189 specific output---e.g., @code{glib:bin} asks for the @code{bin} output
5190 of @code{glib} (@pxref{Packages with Multiple Outputs}).
5192 This option may be composed with the default behavior of @command{guix
5193 environment}. Packages appearing before @code{--ad-hoc} are interpreted
5194 as packages whose dependencies will be added to the environment, the
5195 default behavior. Packages appearing after are interpreted as packages
5196 that will be added to the environment directly.
5199 Unset existing environment variables when building the new environment.
5200 This has the effect of creating an environment in which search paths
5201 only contain package inputs.
5203 @item --search-paths
5204 Display the environment variable definitions that make up the
5207 @item --system=@var{system}
5208 @itemx -s @var{system}
5209 Attempt to build for @var{system}---e.g., @code{i686-linux}.
5214 Run @var{command} within an isolated container. The current working
5215 directory outside the container is mapped inside the
5216 container. Additionally, the spawned process runs as the current user
5217 outside the container, but has root privileges in the context of the
5222 For containers, share the network namespace with the host system.
5223 Containers created without this flag only have access to the loopback
5226 @item --expose=@var{source}[=@var{target}]
5227 For containers, expose the file system @var{source} from the host system
5228 as the read-only file system @var{target} within the container. If
5229 @var{target} is not specified, @var{source} is used as the target mount
5230 point in the container.
5232 The example below spawns a Guile REPL in a container in which the user's
5233 home directory is accessible read-only via the @file{/exchange}
5237 guix environment --container --expose=$HOME=/exchange guile -- guile
5240 @item --share=@var{source}[=@var{target}]
5241 For containers, share the file system @var{source} from the host system
5242 as the writable file system @var{target} within the container. If
5243 @var{target} is not specified, @var{source} is used as the target mount
5244 point in the container.
5246 The example below spawns a Guile REPL in a container in which the user's
5247 home directory is accessible for both reading and writing via the
5248 @file{/exchange} directory:
5251 guix environment --container --share=$HOME=/exchange guile -- guile
5255 It also supports all of the common build options that @command{guix
5256 build} supports (@pxref{Common Build Options}).
5258 @node Invoking guix publish
5259 @section Invoking @command{guix publish}
5261 The purpose of @command{guix publish} is to enable users to easily share
5262 their store with others, who can then use it as a substitute server
5263 (@pxref{Substitutes}).
5265 When @command{guix publish} runs, it spawns an HTTP server which allows
5266 anyone with network access to obtain substitutes from it. This means
5267 that any machine running Guix can also act as if it were a build farm,
5268 since the HTTP interface is compatible with Hydra, the software behind
5269 the @code{hydra.gnu.org} build farm.
5271 For security, each substitute is signed, allowing recipients to check
5272 their authenticity and integrity (@pxref{Substitutes}). Because
5273 @command{guix publish} uses the signing key of the system, which is only
5274 readable by the system administrator, it must be started as root; the
5275 @code{--user} option makes it drop root privileges early on.
5277 The signing key pair must be generated before @command{guix publish} is
5278 launched, using @command{guix archive --generate-key} (@pxref{Invoking
5281 The general syntax is:
5284 guix publish @var{options}@dots{}
5287 Running @command{guix publish} without any additional arguments will
5288 spawn an HTTP server on port 8080:
5294 Once a publishing server has been authorized (@pxref{Invoking guix
5295 archive}), the daemon may download substitutes from it:
5298 guix-daemon --substitute-urls=http://example.org:8080
5301 The following options are available:
5304 @item --port=@var{port}
5305 @itemx -p @var{port}
5306 Listen for HTTP requests on @var{port}.
5308 @item --listen=@var{host}
5309 Listen on the network interface for @var{host}. The default is to
5310 accept connections from any interface.
5312 @item --user=@var{user}
5313 @itemx -u @var{user}
5314 Change privileges to @var{user} as soon as possible---i.e., once the
5315 server socket is open and the signing key has been read.
5317 @item --repl[=@var{port}]
5318 @itemx -r [@var{port}]
5319 Spawn a Guile REPL server (@pxref{REPL Servers,,, guile, GNU Guile
5320 Reference Manual}) on @var{port} (37146 by default). This is used
5321 primarily for debugging a running @command{guix publish} server.
5324 Enabling @command{guix publish} on a GuixSD system is a one-liner: just
5325 add a call to @code{guix-publish-service} in the @code{services} field
5326 of the @code{operating-system} declaration (@pxref{guix-publish-service,
5327 @code{guix-publish-service}}).
5330 @node Invoking guix challenge
5331 @section Invoking @command{guix challenge}
5333 @cindex reproducible builds
5334 @cindex verifiable builds
5336 Do the binaries provided by this server really correspond to the source
5337 code it claims to build? Is a package build process deterministic?
5338 These are the questions the @command{guix challenge} command attempts to
5341 The former is obviously an important question: Before using a substitute
5342 server (@pxref{Substitutes}), one had better @emph{verify} that it
5343 provides the right binaries, and thus @emph{challenge} it. The latter
5344 is what enables the former: If package builds are deterministic, then
5345 independent builds of the package should yield the exact same result,
5346 bit for bit; if a server provides a binary different from the one
5347 obtained locally, it may be either corrupt or malicious.
5349 We know that the hash that shows up in @file{/gnu/store} file names is
5350 the hash of all the inputs of the process that built the file or
5351 directory---compilers, libraries, build scripts,
5352 etc. (@pxref{Introduction}). Assuming deterministic build processes,
5353 one store file name should map to exactly one build output.
5354 @command{guix challenge} checks whether there is, indeed, a single
5355 mapping by comparing the build outputs of several independent builds of
5356 any given store item.
5358 The command output looks like this:
5361 $ guix challenge --substitute-urls="http://hydra.gnu.org http://guix.example.org"
5362 updating list of substitutes from 'http://hydra.gnu.org'... 100.0%
5363 updating list of substitutes from 'http://guix.example.org'... 100.0%
5364 /gnu/store/@dots{}-openssl-1.0.2d contents differ:
5365 local hash: 0725l22r5jnzazaacncwsvp9kgf42266ayyp814v7djxs7nk963q
5366 http://hydra.gnu.org/nar/@dots{}-openssl-1.0.2d: 0725l22r5jnzazaacncwsvp9kgf42266ayyp814v7djxs7nk963q
5367 http://guix.example.org/nar/@dots{}-openssl-1.0.2d: 1zy4fmaaqcnjrzzajkdn3f5gmjk754b43qkq47llbyak9z0qjyim
5368 /gnu/store/@dots{}-git-2.5.0 contents differ:
5369 local hash: 00p3bmryhjxrhpn2gxs2fy0a15lnip05l97205pgbk5ra395hyha
5370 http://hydra.gnu.org/nar/@dots{}-git-2.5.0: 069nb85bv4d4a6slrwjdy8v1cn4cwspm3kdbmyb81d6zckj3nq9f
5371 http://guix.example.org/nar/@dots{}-git-2.5.0: 0mdqa9w1p6cmli6976v4wi0sw9r4p5prkj7lzfd1877wk11c9c73
5372 /gnu/store/@dots{}-pius-2.1.1 contents differ:
5373 local hash: 0k4v3m9z1zp8xzzizb7d8kjj72f9172xv078sq4wl73vnq9ig3ax
5374 http://hydra.gnu.org/nar/@dots{}-pius-2.1.1: 0k4v3m9z1zp8xzzizb7d8kjj72f9172xv078sq4wl73vnq9ig3ax
5375 http://guix.example.org/nar/@dots{}-pius-2.1.1: 1cy25x1a4fzq5rk0pmvc8xhwyffnqz95h2bpvqsz2mpvlbccy0gs
5379 In this example, @command{guix challenge} first scans the store to
5380 determine the set of locally-built derivations---as opposed to store
5381 items that were downloaded from a substitute server---and then queries
5382 all the substitute servers. It then reports those store items for which
5383 the servers obtained a result different from the local build.
5385 @cindex non-determinism, in package builds
5386 As an example, @code{guix.example.org} always gets a different answer.
5387 Conversely, @code{hydra.gnu.org} agrees with local builds, except in the
5388 case of Git. This might indicate that the build process of Git is
5389 non-deterministic, meaning that its output varies as a function of
5390 various things that Guix does not fully control, in spite of building
5391 packages in isolated environments (@pxref{Features}). Most common
5392 sources of non-determinism include the addition of timestamps in build
5393 results, the inclusion of random numbers, and directory listings sorted
5394 by inode number. See @uref{http://reproducible.debian.net/howto/}, for
5397 To find out what is wrong with this Git binary, we can do something along
5398 these lines (@pxref{Invoking guix archive}):
5401 $ wget -q -O - http://hydra.gnu.org/nar/@dots{}-git-2.5.0 \
5402 | guix archive -x /tmp/git
5403 $ diff -ur --no-dereference /gnu/store/@dots{}-git.2.5.0 /tmp/git
5406 This command shows the difference between the files resulting from the
5407 local build, and the files resulting from the build on
5408 @code{hydra.gnu.org} (@pxref{Overview, Comparing and Merging Files,,
5409 diffutils, Comparing and Merging Files}). The @command{diff} command
5410 works great for text files. When binary files differ, a better option
5411 is @uref{http://diffoscope.org/, Diffoscope}, a tool that helps
5412 visualize differences for all kinds of files.
5414 Once you have done that work, you can tell whether the differences are due
5415 to a non-deterministic build process or to a malicious server. We try
5416 hard to remove sources of non-determinism in packages to make it easier
5417 to verify substitutes, but of course, this is a process that
5418 involves not just Guix, but a large part of the free software community.
5419 In the meantime, @command{guix challenge} is one tool to help address
5422 If you are writing packages for Guix, you are encouraged to check
5423 whether @code{hydra.gnu.org} and other substitute servers obtain the
5424 same build result as you did with:
5427 $ guix challenge @var{package}
5431 where @var{package} is a package specification such as
5432 @code{guile-2.0} or @code{glibc:debug}.
5434 The general syntax is:
5437 guix challenge @var{options} [@var{packages}@dots{}]
5440 The one option that matters is:
5444 @item --substitute-urls=@var{urls}
5445 Consider @var{urls} the whitespace-separated list of substitute source
5451 @node Invoking guix container
5452 @section Invoking @command{guix container}
5456 As of version @value{VERSION}, this tool is experimental. The interface
5457 is subject to radical change in the future.
5460 The purpose of @command{guix container} is to manipulate processes
5461 running within an isolated environment, commonly known as a
5462 ``container'', typically created by the @command{guix environment}
5463 (@pxref{Invoking guix environment}) and @command{guix system container}
5464 (@pxref{Invoking guix system}) commands.
5466 The general syntax is:
5469 guix container @var{action} @var{options}@dots{}
5472 @var{action} specifies the operation to perform with a container, and
5473 @var{options} specifies the context-specific arguments for the action.
5475 The following actions are available:
5479 Execute a command within the context of a running container.
5484 guix container exec @var{pid} @var{program} @var{arguments}@dots{}
5487 @var{pid} specifies the process ID of the running container.
5488 @var{program} specifies an executable file name within the root file
5489 system of the container. @var{arguments} are the additional options that
5490 will be passed to @var{program}.
5492 The following command launches an interactive login shell inside a
5493 GuixSD container, started by @command{guix system container}, and whose
5497 guix container exec 9001 /run/current-system/profile/bin/bash --login
5500 Note that the @var{pid} cannot be the parent process of a container. It
5501 must be PID 1 of the container or one of its child processes.
5505 @c *********************************************************************
5506 @node GNU Distribution
5507 @chapter GNU Distribution
5509 @cindex Guix System Distribution
5511 Guix comes with a distribution of the GNU system consisting entirely of
5512 free software@footnote{The term ``free'' here refers to the
5513 @url{http://www.gnu.org/philosophy/free-sw.html,freedom provided to
5514 users of that software}.}. The
5515 distribution can be installed on its own (@pxref{System Installation}),
5516 but it is also possible to install Guix as a package manager on top of
5517 an installed GNU/Linux system (@pxref{Installation}). To distinguish
5518 between the two, we refer to the standalone distribution as the Guix
5519 System Distribution, or GuixSD.
5521 The distribution provides core GNU packages such as GNU libc, GCC, and
5522 Binutils, as well as many GNU and non-GNU applications. The complete
5523 list of available packages can be browsed
5524 @url{http://www.gnu.org/software/guix/packages,on-line} or by
5525 running @command{guix package} (@pxref{Invoking guix package}):
5528 guix package --list-available
5531 Our goal is to provide a practical 100% free software distribution of
5532 Linux-based and other variants of GNU, with a focus on the promotion and
5533 tight integration of GNU components, and an emphasis on programs and
5534 tools that help users exert that freedom.
5536 Packages are currently available on the following platforms:
5541 Intel/AMD @code{x86_64} architecture, Linux-Libre kernel;
5544 Intel 32-bit architecture (IA32), Linux-Libre kernel;
5547 ARMv7-A architecture with hard float, Thumb-2 and NEON,
5548 using the EABI hard-float application binary interface (ABI),
5549 and Linux-Libre kernel.
5551 @item mips64el-linux
5552 little-endian 64-bit MIPS processors, specifically the Loongson series,
5553 n32 ABI, and Linux-Libre kernel.
5557 GuixSD itself is currently only available on @code{i686} and @code{x86_64}.
5560 For information on porting to other architectures or kernels,
5564 * System Installation:: Installing the whole operating system.
5565 * System Configuration:: Configuring the operating system.
5566 * Installing Debugging Files:: Feeding the debugger.
5567 * Security Updates:: Deploying security fixes quickly.
5568 * Package Modules:: Packages from the programmer's viewpoint.
5569 * Packaging Guidelines:: Growing the distribution.
5570 * Bootstrapping:: GNU/Linux built from scratch.
5571 * Porting:: Targeting another platform or kernel.
5574 Building this distribution is a cooperative effort, and you are invited
5575 to join! @xref{Contributing}, for information about how you can help.
5577 @node System Installation
5578 @section System Installation
5580 @cindex Guix System Distribution
5581 This section explains how to install the Guix System Distribution
5582 on a machine. The Guix package manager can
5583 also be installed on top of a running GNU/Linux system,
5584 @pxref{Installation}.
5587 @c This paragraph is for people reading this from tty2 of the
5588 @c installation image.
5589 You're reading this documentation with an Info reader. For details on
5590 how to use it, hit the @key{RET} key (``return'' or ``enter'') on the
5591 link that follows: @pxref{Help,,, info, Info: An Introduction}. Hit
5592 @kbd{l} afterwards to come back here.
5596 * Limitations:: What you can expect.
5597 * USB Stick Installation:: Preparing the installation medium.
5598 * Preparing for Installation:: Networking, partitioning, etc.
5599 * Proceeding with the Installation:: The real thing.
5600 * Building the Installation Image:: How this comes to be.
5604 @subsection Limitations
5606 As of version @value{VERSION}, the Guix System Distribution (GuixSD) is
5607 not production-ready. It may contain bugs and lack important
5608 features. Thus, if you are looking for a stable production system that
5609 respects your freedom as a computer user, a good solution at this point
5610 is to consider @url{http://www.gnu.org/distros/free-distros.html, one of
5611 the more established GNU/Linux distributions}. We hope you can soon switch
5612 to the GuixSD without fear, of course. In the meantime, you can
5613 also keep using your distribution and try out the package manager on top
5614 of it (@pxref{Installation}).
5616 Before you proceed with the installation, be aware of the following
5617 noteworthy limitations applicable to version @value{VERSION}:
5621 The installation process does not include a graphical user interface and
5622 requires familiarity with GNU/Linux (see the following subsections to
5623 get a feel of what that means.)
5626 The system does not yet provide full GNOME and KDE desktops. Xfce and
5627 Enlightenment are available, though, if graphical desktop environments
5628 are your thing, as well as a number of X11 window managers.
5631 Support for the Logical Volume Manager (LVM) is missing.
5634 Few system services are currently supported out-of-the-box
5638 More than 3,000 packages are available, but you may
5639 occasionally find that a useful package is missing.
5642 You have been warned! But more than a disclaimer, this is an invitation
5643 to report issues (and success stories!), and to join us in improving it.
5644 @xref{Contributing}, for more info.
5646 @node USB Stick Installation
5647 @subsection USB Stick Installation
5649 An installation image for USB sticks can be downloaded from
5650 @indicateurl{ftp://alpha.gnu.org/gnu/guix/guixsd-usb-install-@value{VERSION}.@var{system}.xz},
5651 where @var{system} is one of:
5655 for a GNU/Linux system on Intel/AMD-compatible 64-bit CPUs;
5658 for a 32-bit GNU/Linux system on Intel-compatible CPUs.
5661 This image contains a single partition with the tools necessary for an
5662 installation. It is meant to be copied @emph{as is} to a large-enough
5665 To copy the image to a USB stick, follow these steps:
5669 Decompress the image using the @command{xz} command:
5672 xz -d guixsd-usb-install-@value{VERSION}.@var{system}.xz
5676 Insert a USB stick of 1@tie{}GiB or more into your machine, and determine
5677 its device name. Assuming that the USB stick is known as @file{/dev/sdX},
5678 copy the image with:
5681 dd if=guixsd-usb-install-@value{VERSION}.x86_64 of=/dev/sdX
5684 Access to @file{/dev/sdX} usually requires root privileges.
5687 Once this is done, you should be able to reboot the system and boot from
5688 the USB stick. The latter usually requires you to get in the BIOS' boot
5689 menu, where you can choose to boot from the USB stick.
5691 @node Preparing for Installation
5692 @subsection Preparing for Installation
5694 Once you have successfully booted the image on the USB stick, you should
5695 end up with a root prompt. Several console TTYs are configured and can
5696 be used to run commands as root. TTY2 shows this documentation,
5697 browsable using the Info reader commands (@pxref{Help,,, info, Info: An
5698 Introduction}). The installation system runs the GPM mouse daemon,
5699 which allows you to select text with the left mouse button and to paste
5700 it with the middle button.
5702 @subsubsection Keyboard Layout
5704 @cindex keyboard layout
5705 The installation image uses the US qwerty keyboard layout. If you want
5706 to change it, you can use the @command{loadkeys} command. For example,
5707 the following command selects the Dvorak keyboard layout:
5713 See the files under @file{/run/current-system/profile/share/keymaps} for
5714 a list of available keyboard layouts. Run @command{man loadkeys} for
5717 @subsubsection Networking
5719 Run the following command see what your network interfaces are called:
5725 @c http://cgit.freedesktop.org/systemd/systemd/tree/src/udev/udev-builtin-net_id.c#n20
5726 Wired interfaces have a name starting with @samp{e}; for example, the
5727 interface corresponding to the first on-board Ethernet controller is
5728 called @samp{eno1}. Wireless interfaces have a name starting with
5729 @samp{w}, like @samp{w1p2s0}.
5732 @item Wired connection
5733 To configure a wired network run the following command, substituting
5734 @var{interface} with the name of the wired interface you want to use.
5737 ifconfig @var{interface} up
5740 @item Wireless connection
5741 To configure wireless networking, you can create a configuration file
5742 for the @command{wpa_supplicant} configuration tool (its location is not
5743 important) using one of the available text editors such as
5747 zile wpa_supplicant.conf
5750 As an example, the following stanza can go to this file and will work
5751 for many wireless networks, provided you give the actual SSID and
5752 passphrase for the network you are connecting to:
5758 psk="the network's secret passphrase"
5762 Start the wireless service and run it in the background with the
5763 following command (substitute @var{interface} with the name of the
5764 network interface you want to use):
5767 wpa_supplicant -c wpa_supplicant.conf -i @var{interface} -B
5770 Run @command{man wpa_supplication} for more information.
5773 At this point, you need to acquire an IP address. On a network where IP
5774 addresses are automatically assigned @i{via} DHCP, you can run:
5777 dhclient @var{interface}
5780 Try to ping a server to see if networking is up and running:
5786 Setting up network access is almost always a requirement because the
5787 image does not contain all the software and tools that may be needed.
5789 @subsubsection Disk Partitioning
5791 Unless this has already been done, the next step is to partition, and
5792 then format the target partition(s).
5794 The installation image includes several partitioning tools, including
5795 Parted (@pxref{Overview,,, parted, GNU Parted User Manual}),
5796 @command{fdisk}, and @command{cfdisk}. Run it and set up your disk with
5797 the partition layout you want:
5803 Once you are done partitioning the target hard disk drive, you have to
5804 create a file system on the relevant partition(s)@footnote{Currently
5805 GuixSD pretty much assumes an ext4 file system. In particular, code
5806 that reads partition UUIDs and labels only works with ext4. This will
5807 be fixed in the future.}.
5809 Preferably, assign partitions a label so that you can easily and
5810 reliably refer to them in @code{file-system} declarations (@pxref{File
5811 Systems}). This is typically done using the @code{-L} option of
5812 @command{mkfs.ext4} and related commands. So, assuming the target root
5813 partition lives at @file{/dev/sda1}, a file system with the label
5814 @code{my-root} can be created with:
5817 mkfs.ext4 -L my-root /dev/sda1
5820 @c FIXME: Uncomment this once GRUB fully supports encrypted roots.
5821 @c A typical command sequence may be:
5825 @c @dots{} Create partitions etc.@dots{}
5826 @c # cryptsetup luksFormat /dev/sdX1
5827 @c # cryptsetup open --type luks /dev/sdX1 my-partition
5828 @c # mkfs.ext4 -L my-root /dev/mapper/my-partition
5831 In addition to e2fsprogs, the suite of tools to manipulate
5832 ext2/ext3/ext4 file systems, the installation image includes
5833 Cryptsetup/LUKS for disk encryption.
5835 Once that is done, mount the target root partition under @file{/mnt}
5836 with a command like (again, assuming @file{/dev/sda1} is the root
5840 mount /dev/sda1 /mnt
5843 @node Proceeding with the Installation
5844 @subsection Proceeding with the Installation
5846 With the target partitions ready and the target root mounted on
5847 @file{/mnt}, we're ready to go. First, run:
5850 herd start cow-store /mnt
5853 This makes @file{/gnu/store} copy-on-write, such that packages added to
5854 it during the installation phase are written to the target disk rather
5855 than kept in memory.
5857 Next, you have to edit a file and
5858 provide the declaration of the operating system to be installed. To
5859 that end, the installation system comes with two text editors: GNU nano
5860 (@pxref{Top,,, nano, GNU nano Manual}), and GNU Zile, an Emacs clone.
5861 It is better to store that file on the target root file system, say, as
5862 @file{/mnt/etc/config.scm}.
5864 @xref{Using the Configuration System}, for an overview of the
5865 configuration file. The example configurations discussed in that
5866 section are available under @file{/etc/configuration} in the
5867 installation image. Thus, to get started with a system configuration
5868 providing a graphical display server (a ``desktop'' system), you can run
5869 something along these lines:
5873 # cp /etc/configuration/desktop.scm /mnt/etc/config.scm
5874 # zile /mnt/etc/config.scm
5877 You should pay attention to what your configuration file contains, and
5882 Make sure the @code{grub-configuration} form refers to the device you
5883 want to install GRUB on.
5886 Be sure that your partition labels match the value of their respective
5887 @code{device} fields in your @code{file-system} configuration, assuming
5888 your @code{file-system} configuration sets the value of @code{title} to
5892 Once you are done preparing the configuration file, the new system must
5893 be initialized (remember that the target root file system is mounted
5897 guix system init /mnt/etc/config.scm /mnt
5901 This copies all the necessary files and installs GRUB on
5902 @file{/dev/sdX}, unless you pass the @option{--no-grub} option. For
5903 more information, @pxref{Invoking guix system}. This command may trigger
5904 downloads or builds of missing packages, which can take some time.
5906 Once that command has completed---and hopefully succeeded!---you can run
5907 @command{reboot} and boot into the new system. The @code{root} password
5908 in the new system is initially empty; other users' passwords need to be
5909 initialized by running the @command{passwd} command as @code{root},
5910 unless your configuration specifies otherwise
5911 (@pxref{user-account-password, user account passwords}).
5913 Join us on @code{#guix} on the Freenode IRC network or on
5914 @file{guix-devel@@gnu.org} to share your experience---good or not so
5917 @node Building the Installation Image
5918 @subsection Building the Installation Image
5920 The installation image described above was built using the @command{guix
5921 system} command, specifically:
5924 guix system disk-image --image-size=850MiB gnu/system/install.scm
5927 @xref{Invoking guix system}, for more information. See
5928 @file{gnu/system/install.scm} in the source tree for more information
5929 about the installation image.
5931 @node System Configuration
5932 @section System Configuration
5934 @cindex system configuration
5935 The Guix System Distribution supports a consistent whole-system configuration
5936 mechanism. By that we mean that all aspects of the global system
5937 configuration---such as the available system services, timezone and
5938 locale settings, user accounts---are declared in a single place. Such
5939 a @dfn{system configuration} can be @dfn{instantiated}---i.e., effected.
5941 One of the advantages of putting all the system configuration under the
5942 control of Guix is that it supports transactional system upgrades, and
5943 makes it possible to roll-back to a previous system instantiation,
5944 should something go wrong with the new one (@pxref{Features}). Another
5945 one is that it makes it easy to replicate the exact same configuration
5946 across different machines, or at different points in time, without
5947 having to resort to additional administration tools layered on top of
5948 the system's own tools.
5949 @c Yes, we're talking of Puppet, Chef, & co. here. ↑
5951 This section describes this mechanism. First we focus on the system
5952 administrator's viewpoint---explaining how the system is configured and
5953 instantiated. Then we show how this mechanism can be extended, for
5954 instance to support new system services.
5957 * Using the Configuration System:: Customizing your GNU system.
5958 * operating-system Reference:: Detail of operating-system declarations.
5959 * File Systems:: Configuring file system mounts.
5960 * Mapped Devices:: Block device extra processing.
5961 * User Accounts:: Specifying user accounts.
5962 * Locales:: Language and cultural convention settings.
5963 * Services:: Specifying system services.
5964 * Setuid Programs:: Programs running with root privileges.
5965 * X.509 Certificates:: Authenticating HTTPS servers.
5966 * Name Service Switch:: Configuring libc's name service switch.
5967 * Initial RAM Disk:: Linux-Libre bootstrapping.
5968 * GRUB Configuration:: Configuring the boot loader.
5969 * Invoking guix system:: Instantiating a system configuration.
5970 * Running GuixSD in a VM:: How to run GuixSD in a virtual machine.
5971 * Defining Services:: Adding new service definitions.
5974 @node Using the Configuration System
5975 @subsection Using the Configuration System
5977 The operating system is configured by providing an
5978 @code{operating-system} declaration in a file that can then be passed to
5979 the @command{guix system} command (@pxref{Invoking guix system}). A
5980 simple setup, with the default system services, the default Linux-Libre
5981 kernel, initial RAM disk, and boot loader looks like this:
5983 @findex operating-system
5985 @include os-config-bare-bones.texi
5988 This example should be self-describing. Some of the fields defined
5989 above, such as @code{host-name} and @code{bootloader}, are mandatory.
5990 Others, such as @code{packages} and @code{services}, can be omitted, in
5991 which case they get a default value.
5993 Below we discuss the effect of some of the most important fields
5994 (@pxref{operating-system Reference}, for details about all the available
5995 fields), and how to @dfn{instantiate} the operating system using
5996 @command{guix system}.
5998 @unnumberedsubsubsec Globally-Visible Packages
6000 @vindex %base-packages
6001 The @code{packages} field lists packages that will be globally visible
6002 on the system, for all user accounts---i.e., in every user's @code{PATH}
6003 environment variable---in addition to the per-user profiles
6004 (@pxref{Invoking guix package}). The @var{%base-packages} variable
6005 provides all the tools one would expect for basic user and administrator
6006 tasks---including the GNU Core Utilities, the GNU Networking Utilities,
6007 the GNU Zile lightweight text editor, @command{find}, @command{grep},
6008 etc. The example above adds tcpdump to those, taken from the @code{(gnu
6009 packages admin)} module (@pxref{Package Modules}).
6011 @findex specification->package
6012 Referring to packages by variable name, like @var{tcpdump} above, has
6013 the advantage of being unambiguous; it also allows typos and such to be
6014 diagnosed right away as ``unbound variables''. The downside is that one
6015 needs to know which module defines which package, and to augment the
6016 @code{use-package-modules} line accordingly. To avoid that, one can use
6017 the @code{specification->package} procedure of the @code{(gnu packages)}
6018 module, which returns the best package for a given name or name and
6022 (use-modules (gnu packages))
6026 (packages (append (map specification->package
6027 '("tcpdump" "htop" "gnupg-2.0"))
6031 @unnumberedsubsubsec System Services
6033 @vindex %base-services
6034 The @code{services} field lists @dfn{system services} to be made
6035 available when the system starts (@pxref{Services}).
6036 The @code{operating-system} declaration above specifies that, in
6037 addition to the basic services, we want the @command{lshd} secure shell
6038 daemon listening on port 2222 (@pxref{Networking Services,
6039 @code{lsh-service}}). Under the hood,
6040 @code{lsh-service} arranges so that @code{lshd} is started with the
6041 right command-line options, possibly with supporting configuration files
6042 generated as needed (@pxref{Defining Services}).
6044 @cindex customization, of services
6045 @findex modify-services
6046 Occasionally, instead of using the base services as is, you will want to
6047 customize them. For instance, to change the configuration of
6048 @code{guix-daemon} and Mingetty (the console log-in), you may write the
6049 following instead of @var{%base-services}:
6052 (modify-services %base-services
6053 (guix-service-type config =>
6056 (use-substitutes? #f)
6057 (extra-options '("--gc-keep-outputs"))))
6058 (mingetty-service-type config =>
6059 (mingetty-configuration
6061 (motd (plain-file "motd" "Hi there!")))))
6065 The effect here is to change the options passed to @command{guix-daemon}
6066 when it is started, as well as the ``message of the day'' that appears
6067 when logging in at the console. @xref{Service Reference,
6068 @code{modify-services}}, for more on that.
6070 The configuration for a typical ``desktop'' usage, with the X11 display
6071 server, a desktop environment, network management, power management, and
6072 more, would look like this:
6075 @include os-config-desktop.texi
6078 @xref{Desktop Services}, for the exact list of services provided by
6079 @var{%desktop-services}. @xref{X.509 Certificates}, for background
6080 information about the @code{nss-certs} package that is used here.
6082 Again, @var{%desktop-services} is just a list of service objects. If
6083 you want to remove services from there, you can do so using the
6084 procedures for list filtering (@pxref{SRFI-1 Filtering and
6085 Partitioning,,, guile, GNU Guile Reference Manual}). For instance, the
6086 following expression returns a list that contains all the services in
6087 @var{%desktop-services} minus the Avahi service:
6090 (remove (lambda (service)
6091 (eq? (service-kind service) avahi-service-type))
6095 @unnumberedsubsubsec Instantiating the System
6097 Assuming the @code{operating-system} declaration
6098 is stored in the @file{my-system-config.scm}
6099 file, the @command{guix system reconfigure my-system-config.scm} command
6100 instantiates that configuration, and makes it the default GRUB boot
6101 entry (@pxref{Invoking guix system}).
6103 The normal way to change the system's configuration is by updating this
6104 file and re-running @command{guix system reconfigure}. One should never
6105 have to touch files in @command{/etc} or to run commands that modify the
6106 system state such as @command{useradd} or @command{grub-install}. In
6107 fact, you must avoid that since that would not only void your warranty
6108 but also prevent you from rolling back to previous versions of your
6109 system, should you ever need to.
6111 @cindex roll-back, of the operating system
6112 Speaking of roll-back, each time you run @command{guix system
6113 reconfigure}, a new @dfn{generation} of the system is created---without
6114 modifying or deleting previous generations. Old system generations get
6115 an entry in the GRUB boot menu, allowing you to boot them in case
6116 something went wrong with the latest generation. Reassuring, no? The
6117 @command{guix system list-generations} command lists the system
6118 generations available on disk.
6120 @unnumberedsubsubsec The Programming Interface
6122 At the Scheme level, the bulk of an @code{operating-system} declaration
6123 is instantiated with the following monadic procedure (@pxref{The Store
6126 @deffn {Monadic Procedure} operating-system-derivation os
6127 Return a derivation that builds @var{os}, an @code{operating-system}
6128 object (@pxref{Derivations}).
6130 The output of the derivation is a single directory that refers to all
6131 the packages, configuration files, and other supporting files needed to
6132 instantiate @var{os}.
6135 This procedure is provided by the @code{(gnu system)} module. Along
6136 with @code{(gnu services)} (@pxref{Services}), this module contains the
6137 guts of GuixSD. Make sure to visit it!
6140 @node operating-system Reference
6141 @subsection @code{operating-system} Reference
6143 This section summarizes all the options available in
6144 @code{operating-system} declarations (@pxref{Using the Configuration
6147 @deftp {Data Type} operating-system
6148 This is the data type representing an operating system configuration.
6149 By that, we mean all the global system configuration, not per-user
6150 configuration (@pxref{Using the Configuration System}).
6153 @item @code{kernel} (default: @var{linux-libre})
6154 The package object of the operating system kernel to use@footnote{Currently
6155 only the Linux-libre kernel is supported. In the future, it will be
6156 possible to use the GNU@tie{}Hurd.}.
6158 @item @code{kernel-arguments} (default: @code{'()})
6159 List of strings or gexps representing additional arguments to pass on
6160 the kernel's command-line---e.g., @code{("console=ttyS0")}.
6162 @item @code{bootloader}
6163 The system bootloader configuration object. @xref{GRUB Configuration}.
6165 @item @code{initrd} (default: @code{base-initrd})
6166 A two-argument monadic procedure that returns an initial RAM disk for
6167 the Linux kernel. @xref{Initial RAM Disk}.
6169 @item @code{firmware} (default: @var{%base-firmware})
6171 List of firmware packages loadable by the operating system kernel.
6173 The default includes firmware needed for Atheros-based WiFi devices
6174 (Linux-libre module @code{ath9k}.)
6176 @item @code{host-name}
6179 @item @code{hosts-file}
6181 A file-like object (@pxref{G-Expressions, file-like objects}) for use as
6182 @file{/etc/hosts} (@pxref{Host Names,,, libc, The GNU C Library
6183 Reference Manual}). The default is a file with entries for
6184 @code{localhost} and @var{host-name}.
6186 @item @code{mapped-devices} (default: @code{'()})
6187 A list of mapped devices. @xref{Mapped Devices}.
6189 @item @code{file-systems}
6190 A list of file systems. @xref{File Systems}.
6192 @item @code{swap-devices} (default: @code{'()})
6193 @cindex swap devices
6194 A list of strings identifying devices to be used for ``swap space''
6195 (@pxref{Memory Concepts,,, libc, The GNU C Library Reference Manual}).
6196 For example, @code{'("/dev/sda3")}.
6198 @item @code{users} (default: @code{%base-user-accounts})
6199 @itemx @code{groups} (default: @var{%base-groups})
6200 List of user accounts and groups. @xref{User Accounts}.
6202 @item @code{skeletons} (default: @code{(default-skeletons)})
6203 A monadic list of pairs of target file name and files. These are the
6204 files that will be used as skeletons as new accounts are created.
6206 For instance, a valid value may look like this:
6209 (mlet %store-monad ((bashrc (text-file "bashrc" "\
6210 export PATH=$HOME/.guix-profile/bin")))
6211 (return `((".bashrc" ,bashrc))))
6214 @item @code{issue} (default: @var{%default-issue})
6215 A string denoting the contents of the @file{/etc/issue} file, which is
6216 what displayed when users log in on a text console.
6218 @item @code{packages} (default: @var{%base-packages})
6219 The set of packages installed in the global profile, which is accessible
6220 at @file{/run/current-system/profile}.
6222 The default set includes core utilities, but it is good practice to
6223 install non-core utilities in user profiles (@pxref{Invoking guix
6226 @item @code{timezone}
6227 A timezone identifying string---e.g., @code{"Europe/Paris"}.
6229 You can run the @command{tzselect} command to find out which timezone
6230 string corresponds to your region. Choosing an invalid timezone name
6231 causes @command{guix system} to fail.
6233 @item @code{locale} (default: @code{"en_US.utf8"})
6234 The name of the default locale (@pxref{Locale Names,,, libc, The GNU C
6235 Library Reference Manual}). @xref{Locales}, for more information.
6237 @item @code{locale-definitions} (default: @var{%default-locale-definitions})
6238 The list of locale definitions to be compiled and that may be used at
6239 run time. @xref{Locales}.
6241 @item @code{locale-libcs} (default: @code{(list @var{glibc})})
6242 The list of GNU@tie{}libc packages whose locale data and tools are used
6243 to build the locale definitions. @xref{Locales}, for compatibility
6244 considerations that justify this option.
6246 @item @code{name-service-switch} (default: @var{%default-nss})
6247 Configuration of libc's name service switch (NSS)---a
6248 @code{<name-service-switch>} object. @xref{Name Service Switch}, for
6251 @item @code{services} (default: @var{%base-services})
6252 A list of service objects denoting system services. @xref{Services}.
6254 @item @code{pam-services} (default: @code{(base-pam-services)})
6256 @cindex pluggable authentication modules
6257 Linux @dfn{pluggable authentication module} (PAM) services.
6258 @c FIXME: Add xref to PAM services section.
6260 @item @code{setuid-programs} (default: @var{%setuid-programs})
6261 List of string-valued G-expressions denoting setuid programs.
6262 @xref{Setuid Programs}.
6264 @item @code{sudoers-file} (default: @var{%sudoers-specification})
6265 @cindex sudoers file
6266 The contents of the @file{/etc/sudoers} file as a file-like object
6267 (@pxref{G-Expressions, @code{local-file} and @code{plain-file}}).
6269 This file specifies which users can use the @command{sudo} command, what
6270 they are allowed to do, and what privileges they may gain. The default
6271 is that only @code{root} and members of the @code{wheel} group may use
6278 @subsection File Systems
6280 The list of file systems to be mounted is specified in the
6281 @code{file-systems} field of the operating system's declaration
6282 (@pxref{Using the Configuration System}). Each file system is declared
6283 using the @code{file-system} form, like this:
6287 (mount-point "/home")
6288 (device "/dev/sda3")
6292 As usual, some of the fields are mandatory---those shown in the example
6293 above---while others can be omitted. These are described below.
6295 @deftp {Data Type} file-system
6296 Objects of this type represent file systems to be mounted. They
6297 contain the following members:
6301 This is a string specifying the type of the file system---e.g.,
6304 @item @code{mount-point}
6305 This designates the place where the file system is to be mounted.
6308 This names the ``source'' of the file system. By default it is the name
6309 of a node under @file{/dev}, but its meaning depends on the @code{title}
6310 field described below.
6312 @item @code{title} (default: @code{'device})
6313 This is a symbol that specifies how the @code{device} field is to be
6316 When it is the symbol @code{device}, then the @code{device} field is
6317 interpreted as a file name; when it is @code{label}, then @code{device}
6318 is interpreted as a partition label name; when it is @code{uuid},
6319 @code{device} is interpreted as a partition unique identifier (UUID).
6321 UUIDs may be converted from their string representation (as shown by the
6322 @command{tune2fs -l} command) using the @code{uuid} form@footnote{The
6323 @code{uuid} form expects 16-byte UUIDs as defined in
6324 @uref{https://tools.ietf.org/html/rfc4122, RFC@tie{}4122}. This is the
6325 form of UUID used by the ext2 family of file systems and others, but it
6326 is different from ``UUIDs'' found in FAT file systems, for instance.},
6331 (mount-point "/home")
6334 (device (uuid "4dab5feb-d176-45de-b287-9b0a6e4c01cb")))
6337 The @code{label} and @code{uuid} options offer a way to refer to disk
6338 partitions without having to hard-code their actual device
6339 name@footnote{Note that, while it is tempting to use
6340 @file{/dev/disk/by-uuid} and similar device names to achieve the same
6341 result, this is not recommended: These special device nodes are created
6342 by the udev daemon and may be unavailable at the time the device is
6345 However, when a file system's source is a mapped device (@pxref{Mapped
6346 Devices}), its @code{device} field @emph{must} refer to the mapped
6347 device name---e.g., @file{/dev/mapper/root-partition}---and consequently
6348 @code{title} must be set to @code{'device}. This is required so that
6349 the system knows that mounting the file system depends on having the
6350 corresponding device mapping established.
6352 @item @code{flags} (default: @code{'()})
6353 This is a list of symbols denoting mount flags. Recognized flags
6354 include @code{read-only}, @code{bind-mount}, @code{no-dev} (disallow
6355 access to special files), @code{no-suid} (ignore setuid and setgid
6356 bits), and @code{no-exec} (disallow program execution.)
6358 @item @code{options} (default: @code{#f})
6359 This is either @code{#f}, or a string denoting mount options.
6361 @item @code{mount?} (default: @code{#t})
6362 This value indicates whether to automatically mount the file system when
6363 the system is brought up. When set to @code{#f}, the file system gets
6364 an entry in @file{/etc/fstab} (read by the @command{mount} command) but
6365 is not automatically mounted.
6367 @item @code{needed-for-boot?} (default: @code{#f})
6368 This Boolean value indicates whether the file system is needed when
6369 booting. If that is true, then the file system is mounted when the
6370 initial RAM disk (initrd) is loaded. This is always the case, for
6371 instance, for the root file system.
6373 @item @code{check?} (default: @code{#t})
6374 This Boolean indicates whether the file system needs to be checked for
6375 errors before being mounted.
6377 @item @code{create-mount-point?} (default: @code{#f})
6378 When true, the mount point is created if it does not exist yet.
6380 @item @code{dependencies} (default: @code{'()})
6381 This is a list of @code{<file-system>} objects representing file systems
6382 that must be mounted before (and unmounted after) this one.
6384 As an example, consider a hierarchy of mounts: @file{/sys/fs/cgroup} is
6385 a dependency of @file{/sys/fs/cgroup/cpu} and
6386 @file{/sys/fs/cgroup/memory}.
6391 The @code{(gnu system file-systems)} exports the following useful
6394 @defvr {Scheme Variable} %base-file-systems
6395 These are essential file systems that are required on normal systems,
6396 such as @var{%pseudo-terminal-file-system} and @var{%immutable-store} (see
6397 below.) Operating system declarations should always contain at least
6401 @defvr {Scheme Variable} %pseudo-terminal-file-system
6402 This is the file system to be mounted as @file{/dev/pts}. It supports
6403 @dfn{pseudo-terminals} created @i{via} @code{openpty} and similar
6404 functions (@pxref{Pseudo-Terminals,,, libc, The GNU C Library Reference
6405 Manual}). Pseudo-terminals are used by terminal emulators such as
6409 @defvr {Scheme Variable} %shared-memory-file-system
6410 This file system is mounted as @file{/dev/shm} and is used to support
6411 memory sharing across processes (@pxref{Memory-mapped I/O,
6412 @code{shm_open},, libc, The GNU C Library Reference Manual}).
6415 @defvr {Scheme Variable} %immutable-store
6416 This file system performs a read-only ``bind mount'' of
6417 @file{/gnu/store}, making it read-only for all the users including
6418 @code{root}. This prevents against accidental modification by software
6419 running as @code{root} or by system administrators.
6421 The daemon itself is still able to write to the store: it remounts it
6422 read-write in its own ``name space.''
6425 @defvr {Scheme Variable} %binary-format-file-system
6426 The @code{binfmt_misc} file system, which allows handling of arbitrary
6427 executable file types to be delegated to user space. This requires the
6428 @code{binfmt.ko} kernel module to be loaded.
6431 @defvr {Scheme Variable} %fuse-control-file-system
6432 The @code{fusectl} file system, which allows unprivileged users to mount
6433 and unmount user-space FUSE file systems. This requires the
6434 @code{fuse.ko} kernel module to be loaded.
6437 @node Mapped Devices
6438 @subsection Mapped Devices
6440 @cindex device mapping
6441 @cindex mapped devices
6442 The Linux kernel has a notion of @dfn{device mapping}: a block device,
6443 such as a hard disk partition, can be @dfn{mapped} into another device,
6444 with additional processing over the data that flows through
6445 it@footnote{Note that the GNU@tie{}Hurd makes no difference between the
6446 concept of a ``mapped device'' and that of a file system: both boil down
6447 to @emph{translating} input/output operations made on a file to
6448 operations on its backing store. Thus, the Hurd implements mapped
6449 devices, like file systems, using the generic @dfn{translator} mechanism
6450 (@pxref{Translators,,, hurd, The GNU Hurd Reference Manual}).}. A
6451 typical example is encryption device mapping: all writes to the mapped
6452 device are encrypted, and all reads are deciphered, transparently.
6454 Mapped devices are declared using the @code{mapped-device} form:
6458 (source "/dev/sda3")
6460 (type luks-device-mapping))
6464 @cindex disk encryption
6466 This example specifies a mapping from @file{/dev/sda3} to
6467 @file{/dev/mapper/home} using LUKS---the
6468 @url{http://code.google.com/p/cryptsetup,Linux Unified Key Setup}, a
6469 standard mechanism for disk encryption. The @file{/dev/mapper/home}
6470 device can then be used as the @code{device} of a @code{file-system}
6471 declaration (@pxref{File Systems}). The @code{mapped-device} form is
6474 @deftp {Data Type} mapped-device
6475 Objects of this type represent device mappings that will be made when
6476 the system boots up.
6480 This string specifies the name of the block device to be mapped, such as
6484 This string specifies the name of the mapping to be established. For
6485 example, specifying @code{"my-partition"} will lead to the creation of
6486 the @code{"/dev/mapper/my-partition"} device.
6489 This must be a @code{mapped-device-kind} object, which specifies how
6490 @var{source} is mapped to @var{target}.
6494 @defvr {Scheme Variable} luks-device-mapping
6495 This defines LUKS block device encryption using the @command{cryptsetup}
6496 command, from the same-named package. This relies on the
6497 @code{dm-crypt} Linux kernel module.
6501 @subsection User Accounts
6503 User accounts and groups are entirely managed through the
6504 @code{operating-system} declaration. They are specified with the
6505 @code{user-account} and @code{user-group} forms:
6511 (supplementary-groups '("wheel" ;allow use of sudo, etc.
6513 "video" ;video devices such as webcams
6514 "cdrom")) ;the good ol' CD-ROM
6515 (comment "Bob's sister")
6516 (home-directory "/home/alice"))
6519 When booting or upon completion of @command{guix system reconfigure},
6520 the system ensures that only the user accounts and groups specified in
6521 the @code{operating-system} declaration exist, and with the specified
6522 properties. Thus, account or group creations or modifications made by
6523 directly invoking commands such as @command{useradd} are lost upon
6524 reconfiguration or reboot. This ensures that the system remains exactly
6527 @deftp {Data Type} user-account
6528 Objects of this type represent user accounts. The following members may
6533 The name of the user account.
6536 This is the name (a string) or identifier (a number) of the user group
6537 this account belongs to.
6539 @item @code{supplementary-groups} (default: @code{'()})
6540 Optionally, this can be defined as a list of group names that this
6543 @item @code{uid} (default: @code{#f})
6544 This is the user ID for this account (a number), or @code{#f}. In the
6545 latter case, a number is automatically chosen by the system when the
6548 @item @code{comment} (default: @code{""})
6549 A comment about the account, such as the account's owner full name.
6551 @item @code{home-directory}
6552 This is the name of the home directory for the account.
6554 @item @code{shell} (default: Bash)
6555 This is a G-expression denoting the file name of a program to be used as
6556 the shell (@pxref{G-Expressions}).
6558 @item @code{system?} (default: @code{#f})
6559 This Boolean value indicates whether the account is a ``system''
6560 account. System accounts are sometimes treated specially; for instance,
6561 graphical login managers do not list them.
6563 @anchor{user-account-password}
6564 @item @code{password} (default: @code{#f})
6565 You would normally leave this field to @code{#f}, initialize user
6566 passwords as @code{root} with the @command{passwd} command, and then let
6567 users change it with @command{passwd}. Passwords set with
6568 @command{passwd} are of course preserved across reboot and
6571 If you @emph{do} want to have a preset password for an account, then
6572 this field must contain the encrypted password, as a string.
6573 @xref{crypt,,, libc, The GNU C Library Reference Manual}, for more information
6574 on password encryption, and @ref{Encryption,,, guile, GNU Guile Reference
6575 Manual}, for information on Guile's @code{crypt} procedure.
6580 User group declarations are even simpler:
6583 (user-group (name "students"))
6586 @deftp {Data Type} user-group
6587 This type is for, well, user groups. There are just a few fields:
6593 @item @code{id} (default: @code{#f})
6594 The group identifier (a number). If @code{#f}, a new number is
6595 automatically allocated when the group is created.
6597 @item @code{system?} (default: @code{#f})
6598 This Boolean value indicates whether the group is a ``system'' group.
6599 System groups have low numerical IDs.
6601 @item @code{password} (default: @code{#f})
6602 What, user groups can have a password? Well, apparently yes. Unless
6603 @code{#f}, this field specifies the group's password.
6608 For convenience, a variable lists all the basic user groups one may
6611 @defvr {Scheme Variable} %base-groups
6612 This is the list of basic user groups that users and/or packages expect
6613 to be present on the system. This includes groups such as ``root'',
6614 ``wheel'', and ``users'', as well as groups used to control access to
6615 specific devices such as ``audio'', ``disk'', and ``cdrom''.
6618 @defvr {Scheme Variable} %base-user-accounts
6619 This is the list of basic system accounts that programs may expect to
6620 find on a GNU/Linux system, such as the ``nobody'' account.
6622 Note that the ``root'' account is not included here. It is a
6623 special-case and is automatically added whether or not it is specified.
6630 A @dfn{locale} defines cultural conventions for a particular language
6631 and region of the world (@pxref{Locales,,, libc, The GNU C Library
6632 Reference Manual}). Each locale has a name that typically has the form
6633 @code{@var{language}_@var{territory}.@var{codeset}}---e.g.,
6634 @code{fr_LU.utf8} designates the locale for the French language, with
6635 cultural conventions from Luxembourg, and using the UTF-8 encoding.
6637 @cindex locale definition
6638 Usually, you will want to specify the default locale for the machine
6639 using the @code{locale} field of the @code{operating-system} declaration
6640 (@pxref{operating-system Reference, @code{locale}}).
6642 The selected locale is automatically added to the @dfn{locale
6643 definitions} known to the system if needed, with its codeset inferred
6644 from its name---e.g., @code{bo_CN.utf8} will be assumed to use the
6645 @code{UTF-8} codeset. Additional locale definitions can be specified in
6646 the @code{locale-definitions} slot of @code{operating-system}---this is
6647 useful, for instance, if the codeset could not be inferred from the
6648 locale name. The default set of locale definitions includes some widely
6649 used locales, but not all the available locales, in order to save space.
6651 For instance, to add the North Frisian locale for Germany, the value of
6655 (cons (locale-definition
6656 (name "fy_DE.utf8") (source "fy_DE"))
6657 %default-locale-definitions)
6660 Likewise, to save space, one might want @code{locale-definitions} to
6661 list only the locales that are actually used, as in:
6664 (list (locale-definition
6665 (name "ja_JP.eucjp") (source "ja_JP")
6666 (charset "EUC-JP")))
6670 The compiled locale definitions are available at
6671 @file{/run/current-system/locale/X.Y}, where @code{X.Y} is the libc
6672 version, which is the default location where the GNU@tie{}libc provided
6673 by Guix looks for locale data. This can be overridden using the
6674 @code{LOCPATH} environment variable (@pxref{locales-and-locpath,
6675 @code{LOCPATH} and locale packages}).
6677 The @code{locale-definition} form is provided by the @code{(gnu system
6678 locale)} module. Details are given below.
6680 @deftp {Data Type} locale-definition
6681 This is the data type of a locale definition.
6686 The name of the locale. @xref{Locale Names,,, libc, The GNU C Library
6687 Reference Manual}, for more information on locale names.
6690 The name of the source for that locale. This is typically the
6691 @code{@var{language}_@var{territory}} part of the locale name.
6693 @item @code{charset} (default: @code{"UTF-8"})
6694 The ``character set'' or ``code set'' for that locale,
6695 @uref{http://www.iana.org/assignments/character-sets, as defined by
6701 @defvr {Scheme Variable} %default-locale-definitions
6702 An arbitrary list of commonly used UTF-8 locales, used as the default
6703 value of the @code{locale-definitions} field of @code{operating-system}
6707 @cindex normalized codeset in locale names
6708 These locale definitions use the @dfn{normalized codeset} for the part
6709 that follows the dot in the name (@pxref{Using gettextized software,
6710 normalized codeset,, libc, The GNU C Library Reference Manual}). So for
6711 instance it has @code{uk_UA.utf8} but @emph{not}, say,
6715 @subsubsection Locale Data Compatibility Considerations
6717 @cindex incompatibility, of locale data
6718 @code{operating-system} declarations provide a @code{locale-libcs} field
6719 to specify the GNU@tie{}libc packages that are used to compile locale
6720 declarations (@pxref{operating-system Reference}). ``Why would I
6721 care?'', you may ask. Well, it turns out that the binary format of
6722 locale data is occasionally incompatible from one libc version to
6725 @c See <https://sourceware.org/ml/libc-alpha/2015-09/msg00575.html>
6726 @c and <https://lists.gnu.org/archive/html/guix-devel/2015-08/msg00737.html>.
6727 For instance, a program linked against libc version 2.21 is unable to
6728 read locale data produced with libc 2.22; worse, that program
6729 @emph{aborts} instead of simply ignoring the incompatible locale
6730 data@footnote{Versions 2.23 and later of GNU@tie{}libc will simply skip
6731 the incompatible locale data, which is already an improvement.}.
6732 Similarly, a program linked against libc 2.22 can read most, but not
6733 all, the locale data from libc 2.21 (specifically, @code{LC_COLLATE}
6734 data is incompatible); thus calls to @code{setlocale} may fail, but
6735 programs will not abort.
6737 The ``problem'' in GuixSD is that users have a lot of freedom: They can
6738 choose whether and when to upgrade software in their profiles, and might
6739 be using a libc version different from the one the system administrator
6740 used to build the system-wide locale data.
6742 Fortunately, unprivileged users can also install their own locale data
6743 and define @var{GUIX_LOCPATH} accordingly (@pxref{locales-and-locpath,
6744 @code{GUIX_LOCPATH} and locale packages}).
6746 Still, it is best if the system-wide locale data at
6747 @file{/run/current-system/locale} is built for all the libc versions
6748 actually in use on the system, so that all the programs can access
6749 it---this is especially crucial on a multi-user system. To do that, the
6750 administrator can specify several libc packages in the
6751 @code{locale-libcs} field of @code{operating-system}:
6754 (use-package-modules base)
6758 (locale-libcs (list glibc-2.21 (canonical-package glibc))))
6761 This example would lead to a system containing locale definitions for
6762 both libc 2.21 and the current version of libc in
6763 @file{/run/current-system/locale}.
6767 @subsection Services
6769 @cindex system services
6770 An important part of preparing an @code{operating-system} declaration is
6771 listing @dfn{system services} and their configuration (@pxref{Using the
6772 Configuration System}). System services are typically daemons launched
6773 when the system boots, or other actions needed at that time---e.g.,
6774 configuring network access.
6776 Services are managed by the GNU@tie{}Shepherd (@pxref{Introduction,,,
6777 shepherd, The GNU Shepherd Manual}). On a running system, the
6778 @command{herd} command allows you to list the available services, show
6779 their status, start and stop them, or do other specific operations
6780 (@pxref{Jump Start,,, shepherd, The GNU Shepherd Manual}). For example:
6786 The above command, run as @code{root}, lists the currently defined
6787 services. The @command{herd doc} command shows a synopsis of the given
6792 Run libc's name service cache daemon (nscd).
6795 The @command{start}, @command{stop}, and @command{restart} sub-commands
6796 have the effect you would expect. For instance, the commands below stop
6797 the nscd service and restart the Xorg display server:
6801 Service nscd has been stopped.
6802 # herd restart xorg-server
6803 Service xorg-server has been stopped.
6804 Service xorg-server has been started.
6807 The following sections document the available services, starting with
6808 the core services, that may be used in an @code{operating-system}
6812 * Base Services:: Essential system services.
6813 * Networking Services:: Network setup, SSH daemon, etc.
6814 * X Window:: Graphical display.
6815 * Desktop Services:: D-Bus and desktop services.
6816 * Database Services:: SQL databases.
6817 * Mail Services:: IMAP, POP3, SMTP, and all that.
6818 * Web Services:: Web servers.
6819 * Various Services:: Other services.
6823 @subsubsection Base Services
6825 The @code{(gnu services base)} module provides definitions for the basic
6826 services that one expects from the system. The services exported by
6827 this module are listed below.
6829 @defvr {Scheme Variable} %base-services
6830 This variable contains a list of basic services (@pxref{Service Types
6831 and Services}, for more information on service objects) one would
6832 expect from the system: a login service (mingetty) on each tty, syslogd,
6833 libc's name service cache daemon (nscd), the udev device manager, and
6836 This is the default value of the @code{services} field of
6837 @code{operating-system} declarations. Usually, when customizing a
6838 system, you will want to append services to @var{%base-services}, like
6842 (cons* (avahi-service) (lsh-service) %base-services)
6846 @deffn {Scheme Procedure} host-name-service @var{name}
6847 Return a service that sets the host name to @var{name}.
6850 @deffn {Scheme Procedure} mingetty-service @var{config}
6851 Return a service to run mingetty according to @var{config}, a
6852 @code{<mingetty-configuration>} object, which specifies the tty to run, among
6856 @deftp {Data Type} mingetty-configuration
6857 This is the data type representing the configuration of Mingetty, which
6858 implements console log-in.
6863 The name of the console this Mingetty runs on---e.g., @code{"tty1"}.
6866 A file-like object containing the ``message of the day''.
6868 @item @code{auto-login} (default: @code{#f})
6869 When true, this field must be a string denoting the user name under
6870 which the system automatically logs in. When it is @code{#f}, a
6871 user name and password must be entered to log in.
6873 @item @code{login-program} (default: @code{#f})
6874 This must be either @code{#f}, in which case the default log-in program
6875 is used (@command{login} from the Shadow tool suite), or a gexp denoting
6876 the name of the log-in program.
6878 @item @code{login-pause?} (default: @code{#f})
6879 When set to @code{#t} in conjunction with @var{auto-login}, the user
6880 will have to press a key before the log-in shell is launched.
6882 @item @code{mingetty} (default: @var{mingetty})
6883 The Mingetty package to use.
6888 @cindex name service cache daemon
6890 @deffn {Scheme Procedure} nscd-service [@var{config}] [#:glibc glibc] @
6891 [#:name-services '()]
6892 Return a service that runs libc's name service cache daemon (nscd) with the
6893 given @var{config}---an @code{<nscd-configuration>} object. @xref{Name
6894 Service Switch}, for an example.
6897 @defvr {Scheme Variable} %nscd-default-configuration
6898 This is the default @code{<nscd-configuration>} value (see below) used
6899 by @code{nscd-service}. This uses the caches defined by
6900 @var{%nscd-default-caches}; see below.
6903 @deftp {Data Type} nscd-configuration
6904 This is the type representing the name service cache daemon (nscd)
6909 @item @code{name-services} (default: @code{'()})
6910 List of packages denoting @dfn{name services} that must be visible to
6911 the nscd---e.g., @code{(list @var{nss-mdns})}.
6913 @item @code{glibc} (default: @var{glibc})
6914 Package object denoting the GNU C Library providing the @command{nscd}
6917 @item @code{log-file} (default: @code{"/var/log/nscd.log"})
6918 Name of nscd's log file. This is where debugging output goes when
6919 @code{debug-level} is strictly positive.
6921 @item @code{debug-level} (default: @code{0})
6922 Integer denoting the debugging levels. Higher numbers mean more
6923 debugging output is logged.
6925 @item @code{caches} (default: @var{%nscd-default-caches})
6926 List of @code{<nscd-cache>} objects denoting things to be cached; see
6932 @deftp {Data Type} nscd-cache
6933 Data type representing a cache database of nscd and its parameters.
6937 @item @code{database}
6938 This is a symbol representing the name of the database to be cached.
6939 Valid values are @code{passwd}, @code{group}, @code{hosts}, and
6940 @code{services}, which designate the corresponding NSS database
6941 (@pxref{NSS Basics,,, libc, The GNU C Library Reference Manual}).
6943 @item @code{positive-time-to-live}
6944 @itemx @code{negative-time-to-live} (default: @code{20})
6945 A number representing the number of seconds during which a positive or
6946 negative lookup result remains in cache.
6948 @item @code{check-files?} (default: @code{#t})
6949 Whether to check for updates of the files corresponding to
6952 For instance, when @var{database} is @code{hosts}, setting this flag
6953 instructs nscd to check for updates in @file{/etc/hosts} and to take
6956 @item @code{persistent?} (default: @code{#t})
6957 Whether the cache should be stored persistently on disk.
6959 @item @code{shared?} (default: @code{#t})
6960 Whether the cache should be shared among users.
6962 @item @code{max-database-size} (default: 32@tie{}MiB)
6963 Maximum size in bytes of the database cache.
6965 @c XXX: 'suggested-size' and 'auto-propagate?' seem to be expert
6966 @c settings, so leave them out.
6971 @defvr {Scheme Variable} %nscd-default-caches
6972 List of @code{<nscd-cache>} objects used by default by
6973 @code{nscd-configuration} (see above.)
6975 It enables persistent and aggressive caching of service and host name
6976 lookups. The latter provides better host name lookup performance,
6977 resilience in the face of unreliable name servers, and also better
6978 privacy---often the result of host name lookups is in local cache, so
6979 external name servers do not even need to be queried.
6983 @deffn {Scheme Procedure} syslog-service [#:config-file #f]
6984 Return a service that runs @code{syslogd}. If configuration file name
6985 @var{config-file} is not specified, use some reasonable default
6989 @anchor{guix-configuration-type}
6990 @deftp {Data Type} guix-configuration
6991 This data type represents the configuration of the Guix build daemon.
6992 @xref{Invoking guix-daemon}, for more information.
6995 @item @code{guix} (default: @var{guix})
6996 The Guix package to use.
6998 @item @code{build-group} (default: @code{"guixbuild"})
6999 Name of the group for build user accounts.
7001 @item @code{build-accounts} (default: @code{10})
7002 Number of build user accounts to create.
7004 @item @code{authorize-key?} (default: @code{#t})
7005 Whether to authorize the substitute key for @code{hydra.gnu.org}
7006 (@pxref{Substitutes}).
7008 @item @code{use-substitutes?} (default: @code{#t})
7009 Whether to use substitutes.
7011 @item @code{substitute-urls} (default: @var{%default-substitute-urls})
7012 The list of URLs where to look for substitutes by default.
7014 @item @code{extra-options} (default: @code{'()})
7015 List of extra command-line options for @command{guix-daemon}.
7017 @item @code{lsof} (default: @var{lsof})
7018 @itemx @code{lsh} (default: @var{lsh})
7019 The lsof and lsh packages to use.
7024 @deffn {Scheme Procedure} guix-service @var{config}
7025 Return a service that runs the Guix build daemon according to
7029 @deffn {Scheme Procedure} udev-service [#:udev udev]
7030 Run @var{udev}, which populates the @file{/dev} directory dynamically.
7033 @deffn {Scheme Procedure} console-keymap-service @var{file}
7034 @cindex keyboard layout
7035 Return a service to load console keymap from @var{file} using
7036 @command{loadkeys} command.
7039 @deffn {Scheme Procedure} gpm-service-type [#:gpm @var{gpm}] @
7041 Run @var{gpm}, the general-purpose mouse daemon, with the given
7042 command-line @var{options}. GPM allows users to use the mouse in the console,
7043 notably to select, copy, and paste text. The default value of @var{options}
7044 uses the @code{ps2} protocol, which works for both USB and PS/2 mice.
7046 This service is not part of @var{%base-services}.
7049 @anchor{guix-publish-service}
7050 @deffn {Scheme Procedure} guix-publish-service [#:guix @var{guix}] @
7051 [#:port 80] [#:host "localhost"]
7052 Return a service that runs @command{guix publish} listening on @var{host}
7053 and @var{port} (@pxref{Invoking guix publish}).
7055 This assumes that @file{/etc/guix} already contains a signing key pair as
7056 created by @command{guix archive --generate-key} (@pxref{Invoking guix
7057 archive}). If that is not the case, the service will fail to start.
7061 @node Networking Services
7062 @subsubsection Networking Services
7064 The @code{(gnu services networking)} module provides services to configure
7065 the network interface.
7067 @cindex DHCP, networking service
7068 @deffn {Scheme Procedure} dhcp-client-service [#:dhcp @var{isc-dhcp}]
7069 Return a service that runs @var{dhcp}, a Dynamic Host Configuration
7070 Protocol (DHCP) client, on all the non-loopback network interfaces.
7073 @deffn {Scheme Procedure} static-networking-service @var{interface} @var{ip} @
7074 [#:gateway #f] [#:name-services @code{'()}]
7075 Return a service that starts @var{interface} with address @var{ip}. If
7076 @var{gateway} is true, it must be a string specifying the default network
7081 @cindex network management
7082 @deffn {Scheme Procedure} wicd-service [#:wicd @var{wicd}]
7083 Return a service that runs @url{https://launchpad.net/wicd,Wicd}, a network
7084 management daemon that aims to simplify wired and wireless networking.
7086 This service adds the @var{wicd} package to the global profile, providing
7087 several commands to interact with the daemon and configure networking:
7088 @command{wicd-client}, a graphical user interface, and the @command{wicd-cli}
7089 and @command{wicd-curses} user interfaces.
7092 @cindex NetworkManager
7093 @deffn {Scheme Procedure} network-manager-service @
7094 [#:network-manager @var{network-manager}]
7095 Return a service that runs NetworkManager, a network connection manager
7096 that attempting to keep active network connectivity when available.
7099 @deffn {Scheme Procedure} ntp-service [#:ntp @var{ntp}] @
7100 [#:name-service @var{%ntp-servers}]
7101 Return a service that runs the daemon from @var{ntp}, the
7102 @uref{http://www.ntp.org, Network Time Protocol package}. The daemon will
7103 keep the system clock synchronized with that of @var{servers}.
7106 @defvr {Scheme Variable} %ntp-servers
7107 List of host names used as the default NTP servers.
7110 @deffn {Scheme Procedure} tor-service [@var{config-file}] [#:tor @var{tor}]
7111 Return a service to run the @uref{https://torproject.org, Tor} anonymous
7114 The daemon runs as the @code{tor} unprivileged user. It is passed
7115 @var{config-file}, a file-like object, with an additional @code{User tor} line
7116 and lines for hidden services added via @code{tor-hidden-service}. Run
7117 @command{man tor} for information about the configuration file.
7120 @cindex hidden service
7121 @deffn {Scheme Procedure} tor-hidden-service @var{name} @var{mapping}
7122 Define a new Tor @dfn{hidden service} called @var{name} and implementing
7123 @var{mapping}. @var{mapping} is a list of port/host tuples, such as:
7126 '((22 "127.0.0.1:22")
7127 (80 "127.0.0.1:8080"))
7130 In this example, port 22 of the hidden service is mapped to local port 22, and
7131 port 80 is mapped to local port 8080.
7133 This creates a @file{/var/lib/tor/hidden-services/@var{name}} directory, where
7134 the @file{hostname} file contains the @code{.onion} host name for the hidden
7137 See @uref{https://www.torproject.org/docs/tor-hidden-service.html.en, the Tor
7138 project's documentation} for more information.
7141 @deffn {Scheme Procedure} bitlbee-service [#:bitlbee bitlbee] @
7142 [#:interface "127.0.0.1"] [#:port 6667] @
7143 [#:extra-settings ""]
7144 Return a service that runs @url{http://bitlbee.org,BitlBee}, a daemon that
7145 acts as a gateway between IRC and chat networks.
7147 The daemon will listen to the interface corresponding to the IP address
7148 specified in @var{interface}, on @var{port}. @code{127.0.0.1} means that only
7149 local clients can connect, whereas @code{0.0.0.0} means that connections can
7150 come from any networking interface.
7152 In addition, @var{extra-settings} specifies a string to append to the
7156 Furthermore, @code{(gnu services ssh)} provides the following service.
7158 @deffn {Scheme Procedure} lsh-service [#:host-key "/etc/lsh/host-key"] @
7159 [#:daemonic? #t] [#:interfaces '()] [#:port-number 22] @
7160 [#:allow-empty-passwords? #f] [#:root-login? #f] @
7161 [#:syslog-output? #t] [#:x11-forwarding? #t] @
7162 [#:tcp/ip-forwarding? #t] [#:password-authentication? #t] @
7163 [#:public-key-authentication? #t] [#:initialize? #t]
7164 Run the @command{lshd} program from @var{lsh} to listen on port @var{port-number}.
7165 @var{host-key} must designate a file containing the host key, and readable
7168 When @var{daemonic?} is true, @command{lshd} will detach from the
7169 controlling terminal and log its output to syslogd, unless one sets
7170 @var{syslog-output?} to false. Obviously, it also makes lsh-service
7171 depend on existence of syslogd service. When @var{pid-file?} is true,
7172 @command{lshd} writes its PID to the file called @var{pid-file}.
7174 When @var{initialize?} is true, automatically create the seed and host key
7175 upon service activation if they do not exist yet. This may take long and
7176 require interaction.
7178 When @var{initialize?} is false, it is up to the user to initialize the
7179 randomness generator (@pxref{lsh-make-seed,,, lsh, LSH Manual}), and to create
7180 a key pair with the private key stored in file @var{host-key} (@pxref{lshd
7181 basics,,, lsh, LSH Manual}).
7183 When @var{interfaces} is empty, lshd listens for connections on all the
7184 network interfaces; otherwise, @var{interfaces} must be a list of host names
7187 @var{allow-empty-passwords?} specifies whether to accept log-ins with empty
7188 passwords, and @var{root-login?} specifies whether to accept log-ins as
7191 The other options should be self-descriptive.
7194 @defvr {Scheme Variable} %facebook-host-aliases
7195 This variable contains a string for use in @file{/etc/hosts}
7196 (@pxref{Host Names,,, libc, The GNU C Library Reference Manual}). Each
7197 line contains a entry that maps a known server name of the Facebook
7198 on-line service---e.g., @code{www.facebook.com}---to the local
7199 host---@code{127.0.0.1} or its IPv6 equivalent, @code{::1}.
7201 This variable is typically used in the @code{hosts-file} field of an
7202 @code{operating-system} declaration (@pxref{operating-system Reference,
7203 @file{/etc/hosts}}):
7206 (use-modules (gnu) (guix))
7209 (host-name "mymachine")
7212 ;; Create a /etc/hosts file with aliases for "localhost"
7213 ;; and "mymachine", as well as for Facebook servers.
7215 (string-append (local-host-aliases host-name)
7216 %facebook-host-aliases))))
7219 This mechanism can prevent programs running locally, such as Web
7220 browsers, from accessing Facebook.
7223 The @code{(gnu services avahi)} provides the following definition.
7225 @deffn {Scheme Procedure} avahi-service [#:avahi @var{avahi}] @
7226 [#:host-name #f] [#:publish? #t] [#:ipv4? #t] @
7227 [#:ipv6? #t] [#:wide-area? #f] @
7228 [#:domains-to-browse '()]
7229 Return a service that runs @command{avahi-daemon}, a system-wide
7230 mDNS/DNS-SD responder that allows for service discovery and
7231 "zero-configuration" host name lookups (see @uref{http://avahi.org/}), and
7232 extends the name service cache daemon (nscd) so that it can resolve
7233 @code{.local} host names using
7234 @uref{http://0pointer.de/lennart/projects/nss-mdns/, nss-mdns}. Additionally,
7235 add the @var{avahi} package to the system profile so that commands such as
7236 @command{avahi-browse} are directly usable.
7238 If @var{host-name} is different from @code{#f}, use that as the host name to
7239 publish for this machine; otherwise, use the machine's actual host name.
7241 When @var{publish?} is true, publishing of host names and services is allowed;
7242 in particular, avahi-daemon will publish the machine's host name and IP
7243 address via mDNS on the local network.
7245 When @var{wide-area?} is true, DNS-SD over unicast DNS is enabled.
7247 Boolean values @var{ipv4?} and @var{ipv6?} determine whether to use IPv4/IPv6
7253 @subsubsection X Window
7255 Support for the X Window graphical display system---specifically
7256 Xorg---is provided by the @code{(gnu services xorg)} module. Note that
7257 there is no @code{xorg-service} procedure. Instead, the X server is
7258 started by the @dfn{login manager}, currently SLiM.
7260 @deffn {Scheme Procedure} slim-service [#:allow-empty-passwords? #f] @
7261 [#:auto-login? #f] [#:default-user ""] [#:startx] @
7262 [#:theme @var{%default-slim-theme}] @
7263 [#:theme-name @var{%default-slim-theme-name}]
7264 Return a service that spawns the SLiM graphical login manager, which in
7265 turn starts the X display server with @var{startx}, a command as returned by
7266 @code{xorg-start-command}.
7270 SLiM automatically looks for session types described by the @file{.desktop}
7271 files in @file{/run/current-system/profile/share/xsessions} and allows users
7272 to choose a session from the log-in screen using @kbd{F1}. Packages such as
7273 @var{xfce}, @var{sawfish}, and @var{ratpoison} provide @file{.desktop} files;
7274 adding them to the system-wide set of packages automatically makes them
7275 available at the log-in screen.
7277 In addition, @file{~/.xsession} files are honored. When available,
7278 @file{~/.xsession} must be an executable that starts a window manager
7279 and/or other X clients.
7281 When @var{allow-empty-passwords?} is true, allow logins with an empty
7282 password. When @var{auto-login?} is true, log in automatically as
7285 If @var{theme} is @code{#f}, the use the default log-in theme; otherwise
7286 @var{theme} must be a gexp denoting the name of a directory containing the
7287 theme to use. In that case, @var{theme-name} specifies the name of the
7291 @defvr {Scheme Variable} %default-theme
7292 @defvrx {Scheme Variable} %default-theme-name
7293 The G-Expression denoting the default SLiM theme and its name.
7296 @deffn {Scheme Procedure} xorg-start-command [#:guile] @
7297 [#:configuration-file #f] [#:xorg-server @var{xorg-server}]
7298 Return a derivation that builds a @var{guile} script to start the X server
7299 from @var{xorg-server}. @var{configuration-file} is the server configuration
7300 file or a derivation that builds it; when omitted, the result of
7301 @code{xorg-configuration-file} is used.
7303 Usually the X server is started by a login manager.
7306 @deffn {Scheme Procedure} xorg-configuration-file @
7307 [#:drivers '()] [#:resolutions '()] [#:extra-config '()]
7308 Return a configuration file for the Xorg server containing search paths for
7309 all the common drivers.
7311 @var{drivers} must be either the empty list, in which case Xorg chooses a
7312 graphics driver automatically, or a list of driver names that will be tried in
7313 this order---e.g., @code{(\"modesetting\" \"vesa\")}.
7315 Likewise, when @var{resolutions} is the empty list, Xorg chooses an
7316 appropriate screen resolution; otherwise, it must be a list of
7317 resolutions---e.g., @code{((1024 768) (640 480))}.
7319 Last, @var{extra-config} is a list of strings or objects appended to the
7320 @code{text-file*} argument list. It is used to pass extra text to be added
7321 verbatim to the configuration file.
7324 @deffn {Scheme Procedure} screen-locker-service @var{package} [@var{name}]
7325 Add @var{package}, a package for a screen-locker or screen-saver whose
7326 command is @var{program}, to the set of setuid programs and add a PAM entry
7327 for it. For example:
7330 (screen-locker-service xlockmore "xlock")
7333 makes the good ol' XlockMore usable.
7337 @node Desktop Services
7338 @subsubsection Desktop Services
7340 The @code{(gnu services desktop)} module provides services that are
7341 usually useful in the context of a ``desktop'' setup---that is, on a
7342 machine running a graphical display server, possibly with graphical user
7345 To simplify things, the module defines a variable containing the set of
7346 services that users typically expect on a machine with a graphical
7347 environment and networking:
7349 @defvr {Scheme Variable} %desktop-services
7350 This is a list of services that builds upon @var{%base-services} and
7351 adds or adjust services for a typical ``desktop'' setup.
7353 In particular, it adds a graphical login manager (@pxref{X Window,
7354 @code{slim-service}}), screen lockers,
7355 a network management tool (@pxref{Networking
7356 Services, @code{wicd-service}}), energy and color management services,
7357 the @code{elogind} login and seat manager, the Polkit privilege service,
7358 the GeoClue location service, an NTP client (@pxref{Networking
7359 Services}), the Avahi daemon, and has the name service switch service
7360 configured to be able to use @code{nss-mdns} (@pxref{Name Service
7364 The @var{%desktop-services} variable can be used as the @code{services}
7365 field of an @code{operating-system} declaration (@pxref{operating-system
7366 Reference, @code{services}}).
7368 The actual service definitions provided by @code{(gnu services dbus)}
7369 and @code{(gnu services desktop)} are described below.
7371 @deffn {Scheme Procedure} dbus-service [#:dbus @var{dbus}] [#:services '()]
7372 Return a service that runs the ``system bus'', using @var{dbus}, with
7373 support for @var{services}.
7375 @uref{http://dbus.freedesktop.org/, D-Bus} is an inter-process communication
7376 facility. Its system bus is used to allow system services to communicate
7377 and be notified of system-wide events.
7379 @var{services} must be a list of packages that provide an
7380 @file{etc/dbus-1/system.d} directory containing additional D-Bus configuration
7381 and policy files. For example, to allow avahi-daemon to use the system bus,
7382 @var{services} must be equal to @code{(list avahi)}.
7385 @deffn {Scheme Procedure} elogind-service [#:config @var{config}]
7386 Return a service that runs the @code{elogind} login and
7387 seat management daemon. @uref{https://github.com/andywingo/elogind,
7388 Elogind} exposes a D-Bus interface that can be used to know which users
7389 are logged in, know what kind of sessions they have open, suspend the
7390 system, inhibit system suspend, reboot the system, and other tasks.
7392 Elogind handles most system-level power events for a computer, for
7393 example suspending the system when a lid is closed, or shutting it down
7394 when the power button is pressed.
7396 The @var{config} keyword argument specifies the configuration for
7397 elogind, and should be the result of a @code{(elogind-configuration
7398 (@var{parameter} @var{value})...)} invocation. Available parameters and
7399 their default values are:
7402 @item kill-user-processes?
7404 @item kill-only-users
7406 @item kill-exclude-users
7408 @item inhibit-delay-max-seconds
7410 @item handle-power-key
7412 @item handle-suspend-key
7414 @item handle-hibernate-key
7416 @item handle-lid-switch
7418 @item handle-lid-switch-docked
7420 @item power-key-ignore-inhibited?
7422 @item suspend-key-ignore-inhibited?
7424 @item hibernate-key-ignore-inhibited?
7426 @item lid-switch-ignore-inhibited?
7428 @item holdoff-timeout-seconds
7432 @item idle-action-seconds
7434 @item runtime-directory-size-percent
7436 @item runtime-directory-size
7441 @code{("mem" "standby" "freeze")}
7444 @item hibernate-state
7446 @item hibernate-mode
7447 @code{("platform" "shutdown")}
7448 @item hybrid-sleep-state
7450 @item hybrid-sleep-mode
7451 @code{("suspend" "platform" "shutdown")}
7455 @deffn {Scheme Procedure} polkit-service @
7456 [#:polkit @var{polkit}]
7457 Return a service that runs the
7458 @uref{http://www.freedesktop.org/wiki/Software/polkit/, Polkit privilege
7459 management service}, which allows system administrators to grant access to
7460 privileged operations in a structured way. By querying the Polkit service, a
7461 privileged system component can know when it should grant additional
7462 capabilities to ordinary users. For example, an ordinary user can be granted
7463 the capability to suspend the system if the user is logged in locally.
7466 @deffn {Scheme Procedure} upower-service [#:upower @var{upower}] @
7467 [#:watts-up-pro? #f] @
7468 [#:poll-batteries? #t] @
7469 [#:ignore-lid? #f] @
7470 [#:use-percentage-for-policy? #f] @
7471 [#:percentage-low 10] @
7472 [#:percentage-critical 3] @
7473 [#:percentage-action 2] @
7475 [#:time-critical 300] @
7476 [#:time-action 120] @
7477 [#:critical-power-action 'hybrid-sleep]
7478 Return a service that runs @uref{http://upower.freedesktop.org/,
7479 @command{upowerd}}, a system-wide monitor for power consumption and battery
7480 levels, with the given configuration settings. It implements the
7481 @code{org.freedesktop.UPower} D-Bus interface, and is notably used by
7485 @deffn {Scheme Procedure} udisks-service [#:udisks @var{udisks}]
7486 Return a service for @uref{http://udisks.freedesktop.org/docs/latest/,
7487 UDisks}, a @dfn{disk management} daemon that provides user interfaces with
7488 notifications and ways to mount/unmount disks. Programs that talk to UDisks
7489 include the @command{udisksctl} command, part of UDisks, and GNOME Disks.
7492 @deffn {Scheme Procedure} colord-service [#:colord @var{colord}]
7493 Return a service that runs @command{colord}, a system service with a D-Bus
7494 interface to manage the color profiles of input and output devices such as
7495 screens and scanners. It is notably used by the GNOME Color Manager graphical
7496 tool. See @uref{http://www.freedesktop.org/software/colord/, the colord web
7497 site} for more information.
7500 @deffn {Scheme Procedure} geoclue-application name [#:allowed? #t] [#:system? #f] [#:users '()]
7501 Return an configuration allowing an application to access GeoClue
7502 location data. @var{name} is the Desktop ID of the application, without
7503 the @code{.desktop} part. If @var{allowed?} is true, the application
7504 will have access to location information by default. The boolean
7505 @var{system?} value indicates that an application is a system component
7506 or not. Finally @var{users} is a list of UIDs of all users for which
7507 this application is allowed location info access. An empty users list
7508 means that all users are allowed.
7511 @defvr {Scheme Variable} %standard-geoclue-applications
7512 The standard list of well-known GeoClue application configurations,
7513 granting authority to GNOME's date-and-time utility to ask for the
7514 current location in order to set the time zone, and allowing the Firefox
7515 (IceCat) and Epiphany web browsers to request location information.
7516 Firefox and Epiphany both query the user before allowing a web page to
7517 know the user's location.
7520 @deffn {Scheme Procedure} geoclue-service [#:colord @var{colord}] @
7522 [#:wifi-geolocation-url "https://location.services.mozilla.com/v1/geolocate?key=geoclue"] @
7524 [#:wifi-submission-url "https://location.services.mozilla.com/v1/submit?key=geoclue"] @
7525 [#:submission-nick "geoclue"] @
7526 [#:applications %standard-geoclue-applications]
7527 Return a service that runs the GeoClue location service. This service
7528 provides a D-Bus interface to allow applications to request access to a
7529 user's physical location, and optionally to add information to online
7530 location databases. See
7531 @uref{https://wiki.freedesktop.org/www/Software/GeoClue/, the GeoClue
7532 web site} for more information.
7535 @node Database Services
7536 @subsubsection Database Services
7538 The @code{(gnu services databases)} module provides the following service.
7540 @deffn {Scheme Procedure} postgresql-service [#:postgresql postgresql] @
7541 [#:config-file] [#:data-directory ``/var/lib/postgresql/data'']
7542 Return a service that runs @var{postgresql}, the PostgreSQL database
7545 The PostgreSQL daemon loads its runtime configuration from
7546 @var{config-file} and stores the database cluster in
7547 @var{data-directory}.
7551 @subsubsection Mail Services
7553 The @code{(gnu services mail)} module provides Guix service definitions
7554 for mail services. Currently the only implemented service is Dovecot,
7555 an IMAP, POP3, and LMTP server.
7557 Guix does not yet have a mail transfer agent (MTA), although for some
7558 lightweight purposes the @code{esmtp} relay-only MTA may suffice. Help
7559 is needed to properly integrate a full MTA, such as Postfix. Patches
7562 To add an IMAP/POP3 server to a GuixSD system, add a
7563 @code{dovecot-service} to the operating system definition:
7565 @deffn {Scheme Procedure} dovecot-service [#:config (dovecot-configuration)]
7566 Return a service that runs the Dovecot IMAP/POP3/LMTP mail server.
7569 By default, Dovecot doesn't need much configuration; the default
7570 configuration object created by @code{(dovecot-configuration)} will
7571 suffice if your mail is delivered to @code{~/Maildir}. A self-signed
7572 certificate will be generated for TLS-protected connections, though
7573 Dovecot will also listen on cleartext ports by default. There are a
7574 number of options though which mail administrators might need to change,
7575 and as is the case with other services, Guix allows the system
7576 administrator to specify these parameters via a uniform Scheme interface.
7578 For example, to specify that mail is located at @code{maildir~/.mail},
7579 one would instantiate the Dovecot service like this:
7582 (dovecot-service #:config
7583 (dovecot-configuration
7584 (mail-location "maildir:~/.mail")))
7587 The available configuration parameters follow. Each parameter
7588 definition is preceded by its type; for example, @samp{string-list foo}
7589 indicates that the @code{foo} parameter should be specified as a list of
7590 strings. There is also a way to specify the configuration as a string,
7591 if you have an old @code{dovecot.conf} file that you want to port over
7592 from some other system; see the end for more details.
7594 @c The following documentation was initially generated by
7595 @c (generate-documentation) in (gnu services mail). Manually maintained
7596 @c documentation is better, so we shouldn't hesitate to edit below as
7597 @c needed. However if the change you want to make to this documentation
7598 @c can be done in an automated way, it's probably easier to change
7599 @c (generate-documentation) than to make it below and have to deal with
7600 @c the churn as dovecot updates.
7602 Available @code{dovecot-configuration} fields are:
7604 @deftypevr {@code{dovecot-configuration} parameter} package dovecot
7605 The dovecot package.
7608 @deftypevr {@code{dovecot-configuration} parameter} comma-separated-string-list listen
7609 A list of IPs or hosts where to listen in for connections. @samp{*}
7610 listens in all IPv4 interfaces, @samp{::} listens in all IPv6
7611 interfaces. If you want to specify non-default ports or anything more
7612 complex, customize the address and port fields of the
7613 @samp{inet-listener} of the specific services you are interested in.
7616 @deftypevr {@code{dovecot-configuration} parameter} protocol-configuration-list protocols
7617 List of protocols we want to serve. Available protocols include
7618 @samp{imap}, @samp{pop3}, and @samp{lmtp}.
7620 Available @code{protocol-configuration} fields are:
7622 @deftypevr {@code{protocol-configuration} parameter} string name
7623 The name of the protocol.
7626 @deftypevr {@code{protocol-configuration} parameter} string auth-socket-path
7627 UNIX socket path to master authentication server to find users.
7628 This is used by imap (for shared users) and lda.
7629 Defaults to @samp{"/var/run/dovecot/auth-userdb"}.
7632 @deftypevr {@code{protocol-configuration} parameter} space-separated-string-list mail-plugins
7633 Space separated list of plugins to load.
7636 @deftypevr {@code{protocol-configuration} parameter} non-negative-integer mail-max-userip-connections
7637 Maximum number of IMAP connections allowed for a user from each IP
7638 address. NOTE: The username is compared case-sensitively.
7639 Defaults to @samp{10}.
7644 @deftypevr {@code{dovecot-configuration} parameter} service-configuration-list services
7645 List of services to enable. Available services include @samp{imap},
7646 @samp{imap-login}, @samp{pop3}, @samp{pop3-login}, @samp{auth}, and
7649 Available @code{service-configuration} fields are:
7651 @deftypevr {@code{service-configuration} parameter} string kind
7652 The service kind. Valid values include @code{director},
7653 @code{imap-login}, @code{pop3-login}, @code{lmtp}, @code{imap},
7654 @code{pop3}, @code{auth}, @code{auth-worker}, @code{dict},
7655 @code{tcpwrap}, @code{quota-warning}, or anything else.
7658 @deftypevr {@code{service-configuration} parameter} listener-configuration-list listeners
7659 Listeners for the service. A listener is either an
7660 @code{unix-listener-configuration}, a @code{fifo-listener-configuration}, or
7661 an @code{inet-listener-configuration}.
7662 Defaults to @samp{()}.
7664 Available @code{unix-listener-configuration} fields are:
7666 @deftypevr {@code{unix-listener-configuration} parameter} file-name path
7667 The file name on which to listen.
7670 @deftypevr {@code{unix-listener-configuration} parameter} string mode
7671 The access mode for the socket.
7672 Defaults to @samp{"0600"}.
7675 @deftypevr {@code{unix-listener-configuration} parameter} string user
7676 The user to own the socket.
7677 Defaults to @samp{""}.
7680 @deftypevr {@code{unix-listener-configuration} parameter} string group
7681 The group to own the socket.
7682 Defaults to @samp{""}.
7686 Available @code{fifo-listener-configuration} fields are:
7688 @deftypevr {@code{fifo-listener-configuration} parameter} file-name path
7689 The file name on which to listen.
7692 @deftypevr {@code{fifo-listener-configuration} parameter} string mode
7693 The access mode for the socket.
7694 Defaults to @samp{"0600"}.
7697 @deftypevr {@code{fifo-listener-configuration} parameter} string user
7698 The user to own the socket.
7699 Defaults to @samp{""}.
7702 @deftypevr {@code{fifo-listener-configuration} parameter} string group
7703 The group to own the socket.
7704 Defaults to @samp{""}.
7708 Available @code{inet-listener-configuration} fields are:
7710 @deftypevr {@code{inet-listener-configuration} parameter} string protocol
7711 The protocol to listen for.
7714 @deftypevr {@code{inet-listener-configuration} parameter} string address
7715 The address on which to listen, or empty for all addresses.
7716 Defaults to @samp{""}.
7719 @deftypevr {@code{inet-listener-configuration} parameter} non-negative-integer port
7720 The port on which to listen.
7723 @deftypevr {@code{inet-listener-configuration} parameter} boolean ssl?
7724 Whether to use SSL for this service; @samp{yes}, @samp{no}, or
7726 Defaults to @samp{#t}.
7731 @deftypevr {@code{service-configuration} parameter} non-negative-integer service-count
7732 Number of connections to handle before starting a new process.
7733 Typically the only useful values are 0 (unlimited) or 1. 1 is more
7734 secure, but 0 is faster. <doc/wiki/LoginProcess.txt>.
7735 Defaults to @samp{1}.
7738 @deftypevr {@code{service-configuration} parameter} non-negative-integer process-min-avail
7739 Number of processes to always keep waiting for more connections.
7740 Defaults to @samp{0}.
7743 @deftypevr {@code{service-configuration} parameter} non-negative-integer vsz-limit
7744 If you set @samp{service-count 0}, you probably need to grow
7746 Defaults to @samp{256000000}.
7751 @deftypevr {@code{dovecot-configuration} parameter} dict-configuration dict
7752 Dict configuration, as created by the @code{dict-configuration}
7755 Available @code{dict-configuration} fields are:
7757 @deftypevr {@code{dict-configuration} parameter} free-form-fields entries
7758 A list of key-value pairs that this dict should hold.
7759 Defaults to @samp{()}.
7764 @deftypevr {@code{dovecot-configuration} parameter} passdb-configuration-list passdbs
7765 List of passdb configurations, each one created by the
7766 @code{passdb-configuration} constructor.
7768 Available @code{passdb-configuration} fields are:
7770 @deftypevr {@code{passdb-configuration} parameter} string driver
7771 The driver that the passdb should use. Valid values include
7772 @samp{pam}, @samp{passwd}, @samp{shadow}, @samp{bsdauth}, and
7774 Defaults to @samp{"pam"}.
7777 @deftypevr {@code{passdb-configuration} parameter} free-form-args args
7778 A list of key-value args to the passdb driver.
7779 Defaults to @samp{()}.
7784 @deftypevr {@code{dovecot-configuration} parameter} userdb-configuration-list userdbs
7785 List of userdb configurations, each one created by the
7786 @code{userdb-configuration} constructor.
7788 Available @code{userdb-configuration} fields are:
7790 @deftypevr {@code{userdb-configuration} parameter} string driver
7791 The driver that the userdb should use. Valid values include
7792 @samp{passwd} and @samp{static}.
7793 Defaults to @samp{"passwd"}.
7796 @deftypevr {@code{userdb-configuration} parameter} free-form-args args
7797 A list of key-value args to the userdb driver.
7798 Defaults to @samp{()}.
7801 @deftypevr {@code{userdb-configuration} parameter} free-form-args override-fields
7802 Override fields from passwd.
7803 Defaults to @samp{()}.
7808 @deftypevr {@code{dovecot-configuration} parameter} plugin-configuration plugin-configuration
7809 Plug-in configuration, created by the @code{plugin-configuration}
7813 @deftypevr {@code{dovecot-configuration} parameter} list-of-namespace-configuration namespaces
7814 List of namespaces. Each item in the list is created by the
7815 @code{namespace-configuration} constructor.
7817 Available @code{namespace-configuration} fields are:
7819 @deftypevr {@code{namespace-configuration} parameter} string name
7820 Name for this namespace.
7823 @deftypevr {@code{namespace-configuration} parameter} string type
7824 Namespace type: @samp{private}, @samp{shared} or @samp{public}.
7825 Defaults to @samp{"private"}.
7828 @deftypevr {@code{namespace-configuration} parameter} string separator
7829 Hierarchy separator to use. You should use the same separator for
7830 all namespaces or some clients get confused. @samp{/} is usually a good
7831 one. The default however depends on the underlying mail storage
7833 Defaults to @samp{""}.
7836 @deftypevr {@code{namespace-configuration} parameter} string prefix
7837 Prefix required to access this namespace. This needs to be
7838 different for all namespaces. For example @samp{Public/}.
7839 Defaults to @samp{""}.
7842 @deftypevr {@code{namespace-configuration} parameter} string location
7843 Physical location of the mailbox. This is in same format as
7844 mail_location, which is also the default for it.
7845 Defaults to @samp{""}.
7848 @deftypevr {@code{namespace-configuration} parameter} boolean inbox?
7849 There can be only one INBOX, and this setting defines which
7851 Defaults to @samp{#f}.
7854 @deftypevr {@code{namespace-configuration} parameter} boolean hidden?
7855 If namespace is hidden, it's not advertised to clients via NAMESPACE
7856 extension. You'll most likely also want to set @samp{list? #f}. This is mostly
7857 useful when converting from another server with different namespaces
7858 which you want to deprecate but still keep working. For example you can
7859 create hidden namespaces with prefixes @samp{~/mail/}, @samp{~%u/mail/}
7861 Defaults to @samp{#f}.
7864 @deftypevr {@code{namespace-configuration} parameter} boolean list?
7865 Show the mailboxes under this namespace with LIST command. This
7866 makes the namespace visible for clients that don't support NAMESPACE
7867 extension. The special @code{children} value lists child mailboxes, but
7868 hides the namespace prefix.
7869 Defaults to @samp{#t}.
7872 @deftypevr {@code{namespace-configuration} parameter} boolean subscriptions?
7873 Namespace handles its own subscriptions. If set to @code{#f}, the
7874 parent namespace handles them. The empty prefix should always have this
7876 Defaults to @samp{#t}.
7879 @deftypevr {@code{namespace-configuration} parameter} mailbox-configuration-list mailboxes
7880 List of predefined mailboxes in this namespace.
7881 Defaults to @samp{()}.
7883 Available @code{mailbox-configuration} fields are:
7885 @deftypevr {@code{mailbox-configuration} parameter} string name
7886 Name for this mailbox.
7889 @deftypevr {@code{mailbox-configuration} parameter} string auto
7890 @samp{create} will automatically create this mailbox.
7891 @samp{subscribe} will both create and subscribe to the mailbox.
7892 Defaults to @samp{"no"}.
7895 @deftypevr {@code{mailbox-configuration} parameter} space-separated-string-list special-use
7896 List of IMAP @code{SPECIAL-USE} attributes as specified by RFC 6154.
7897 Valid values are @code{\All}, @code{\Archive}, @code{\Drafts},
7898 @code{\Flagged}, @code{\Junk}, @code{\Sent}, and @code{\Trash}.
7899 Defaults to @samp{()}.
7906 @deftypevr {@code{dovecot-configuration} parameter} file-name base-dir
7907 Base directory where to store runtime data.
7908 Defaults to @samp{"/var/run/dovecot/"}.
7911 @deftypevr {@code{dovecot-configuration} parameter} string login-greeting
7912 Greeting message for clients.
7913 Defaults to @samp{"Dovecot ready."}.
7916 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-trusted-networks
7917 List of trusted network ranges. Connections from these IPs are
7918 allowed to override their IP addresses and ports (for logging and for
7919 authentication checks). @samp{disable-plaintext-auth} is also ignored
7920 for these networks. Typically you'd specify your IMAP proxy servers
7922 Defaults to @samp{()}.
7925 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-access-sockets
7926 List of login access check sockets (e.g. tcpwrap).
7927 Defaults to @samp{()}.
7930 @deftypevr {@code{dovecot-configuration} parameter} boolean verbose-proctitle?
7931 Show more verbose process titles (in ps). Currently shows user name
7932 and IP address. Useful for seeing who are actually using the IMAP
7933 processes (e.g. shared mailboxes or if same uid is used for multiple
7935 Defaults to @samp{#f}.
7938 @deftypevr {@code{dovecot-configuration} parameter} boolean shutdown-clients?
7939 Should all processes be killed when Dovecot master process shuts down.
7940 Setting this to @code{#f} means that Dovecot can be upgraded without
7941 forcing existing client connections to close (although that could also
7942 be a problem if the upgrade is e.g. because of a security fix).
7943 Defaults to @samp{#t}.
7946 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer doveadm-worker-count
7947 If non-zero, run mail commands via this many connections to doveadm
7948 server, instead of running them directly in the same process.
7949 Defaults to @samp{0}.
7952 @deftypevr {@code{dovecot-configuration} parameter} string doveadm-socket-path
7953 UNIX socket or host:port used for connecting to doveadm server.
7954 Defaults to @samp{"doveadm-server"}.
7957 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list import-environment
7958 List of environment variables that are preserved on Dovecot startup
7959 and passed down to all of its child processes. You can also give
7960 key=value pairs to always set specific settings.
7963 @deftypevr {@code{dovecot-configuration} parameter} boolean disable-plaintext-auth?
7964 Disable LOGIN command and all other plaintext authentications unless
7965 SSL/TLS is used (LOGINDISABLED capability). Note that if the remote IP
7966 matches the local IP (i.e. you're connecting from the same computer),
7967 the connection is considered secure and plaintext authentication is
7968 allowed. See also ssl=required setting.
7969 Defaults to @samp{#t}.
7972 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer auth-cache-size
7973 Authentication cache size (e.g. @samp{#e10e6}). 0 means it's disabled.
7974 Note that bsdauth, PAM and vpopmail require @samp{cache-key} to be set
7975 for caching to be used.
7976 Defaults to @samp{0}.
7979 @deftypevr {@code{dovecot-configuration} parameter} string auth-cache-ttl
7980 Time to live for cached data. After TTL expires the cached record
7981 is no longer used, *except* if the main database lookup returns internal
7982 failure. We also try to handle password changes automatically: If
7983 user's previous authentication was successful, but this one wasn't, the
7984 cache isn't used. For now this works only with plaintext
7986 Defaults to @samp{"1 hour"}.
7989 @deftypevr {@code{dovecot-configuration} parameter} string auth-cache-negative-ttl
7990 TTL for negative hits (user not found, password mismatch).
7991 0 disables caching them completely.
7992 Defaults to @samp{"1 hour"}.
7995 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list auth-realms
7996 List of realms for SASL authentication mechanisms that need them.
7997 You can leave it empty if you don't want to support multiple realms.
7998 Many clients simply use the first one listed here, so keep the default
8000 Defaults to @samp{()}.
8003 @deftypevr {@code{dovecot-configuration} parameter} string auth-default-realm
8004 Default realm/domain to use if none was specified. This is used for
8005 both SASL realms and appending @@domain to username in plaintext
8007 Defaults to @samp{""}.
8010 @deftypevr {@code{dovecot-configuration} parameter} string auth-username-chars
8011 List of allowed characters in username. If the user-given username
8012 contains a character not listed in here, the login automatically fails.
8013 This is just an extra check to make sure user can't exploit any
8014 potential quote escaping vulnerabilities with SQL/LDAP databases. If
8015 you want to allow all characters, set this value to empty.
8016 Defaults to @samp{"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890.-_@@"}.
8019 @deftypevr {@code{dovecot-configuration} parameter} string auth-username-translation
8020 Username character translations before it's looked up from
8021 databases. The value contains series of from -> to characters. For
8022 example @samp{#@@/@@} means that @samp{#} and @samp{/} characters are
8023 translated to @samp{@@}.
8024 Defaults to @samp{""}.
8027 @deftypevr {@code{dovecot-configuration} parameter} string auth-username-format
8028 Username formatting before it's looked up from databases. You can
8029 use the standard variables here, e.g. %Lu would lowercase the username,
8030 %n would drop away the domain if it was given, or @samp{%n-AT-%d} would
8031 change the @samp{@@} into @samp{-AT-}. This translation is done after
8032 @samp{auth-username-translation} changes.
8033 Defaults to @samp{"%Lu"}.
8036 @deftypevr {@code{dovecot-configuration} parameter} string auth-master-user-separator
8037 If you want to allow master users to log in by specifying the master
8038 username within the normal username string (i.e. not using SASL
8039 mechanism's support for it), you can specify the separator character
8040 here. The format is then <username><separator><master username>.
8041 UW-IMAP uses @samp{*} as the separator, so that could be a good
8043 Defaults to @samp{""}.
8046 @deftypevr {@code{dovecot-configuration} parameter} string auth-anonymous-username
8047 Username to use for users logging in with ANONYMOUS SASL
8049 Defaults to @samp{"anonymous"}.
8052 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer auth-worker-max-count
8053 Maximum number of dovecot-auth worker processes. They're used to
8054 execute blocking passdb and userdb queries (e.g. MySQL and PAM).
8055 They're automatically created and destroyed as needed.
8056 Defaults to @samp{30}.
8059 @deftypevr {@code{dovecot-configuration} parameter} string auth-gssapi-hostname
8060 Host name to use in GSSAPI principal names. The default is to use
8061 the name returned by gethostname(). Use @samp{$ALL} (with quotes) to
8062 allow all keytab entries.
8063 Defaults to @samp{""}.
8066 @deftypevr {@code{dovecot-configuration} parameter} string auth-krb5-keytab
8067 Kerberos keytab to use for the GSSAPI mechanism. Will use the
8068 system default (usually /etc/krb5.keytab) if not specified. You may
8069 need to change the auth service to run as root to be able to read this
8071 Defaults to @samp{""}.
8074 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-use-winbind?
8075 Do NTLM and GSS-SPNEGO authentication using Samba's winbind daemon
8076 and @samp{ntlm-auth} helper.
8077 <doc/wiki/Authentication/Mechanisms/Winbind.txt>.
8078 Defaults to @samp{#f}.
8081 @deftypevr {@code{dovecot-configuration} parameter} file-name auth-winbind-helper-path
8082 Path for Samba's @samp{ntlm-auth} helper binary.
8083 Defaults to @samp{"/usr/bin/ntlm_auth"}.
8086 @deftypevr {@code{dovecot-configuration} parameter} string auth-failure-delay
8087 Time to delay before replying to failed authentications.
8088 Defaults to @samp{"2 secs"}.
8091 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-ssl-require-client-cert?
8092 Require a valid SSL client certificate or the authentication
8094 Defaults to @samp{#f}.
8097 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-ssl-username-from-cert?
8098 Take the username from client's SSL certificate, using
8099 @code{X509_NAME_get_text_by_NID()} which returns the subject's DN's
8101 Defaults to @samp{#f}.
8104 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list auth-mechanisms
8105 List of wanted authentication mechanisms. Supported mechanisms are:
8106 @samp{plain}, @samp{login}, @samp{digest-md5}, @samp{cram-md5},
8107 @samp{ntlm}, @samp{rpa}, @samp{apop}, @samp{anonymous}, @samp{gssapi},
8108 @samp{otp}, @samp{skey}, and @samp{gss-spnego}. NOTE: See also
8109 @samp{disable-plaintext-auth} setting.
8112 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list director-servers
8113 List of IPs or hostnames to all director servers, including ourself.
8114 Ports can be specified as ip:port. The default port is the same as what
8115 director service's @samp{inet-listener} is using.
8116 Defaults to @samp{()}.
8119 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list director-mail-servers
8120 List of IPs or hostnames to all backend mail servers. Ranges are
8121 allowed too, like 10.0.0.10-10.0.0.30.
8122 Defaults to @samp{()}.
8125 @deftypevr {@code{dovecot-configuration} parameter} string director-user-expire
8126 How long to redirect users to a specific server after it no longer
8127 has any connections.
8128 Defaults to @samp{"15 min"}.
8131 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer director-doveadm-port
8132 TCP/IP port that accepts doveadm connections (instead of director
8133 connections) If you enable this, you'll also need to add
8134 @samp{inet-listener} for the port.
8135 Defaults to @samp{0}.
8138 @deftypevr {@code{dovecot-configuration} parameter} string director-username-hash
8139 How the username is translated before being hashed. Useful values
8140 include %Ln if user can log in with or without @@domain, %Ld if mailboxes
8141 are shared within domain.
8142 Defaults to @samp{"%Lu"}.
8145 @deftypevr {@code{dovecot-configuration} parameter} string log-path
8146 Log file to use for error messages. @samp{syslog} logs to syslog,
8147 @samp{/dev/stderr} logs to stderr.
8148 Defaults to @samp{"syslog"}.
8151 @deftypevr {@code{dovecot-configuration} parameter} string info-log-path
8152 Log file to use for informational messages. Defaults to
8154 Defaults to @samp{""}.
8157 @deftypevr {@code{dovecot-configuration} parameter} string debug-log-path
8158 Log file to use for debug messages. Defaults to
8159 @samp{info-log-path}.
8160 Defaults to @samp{""}.
8163 @deftypevr {@code{dovecot-configuration} parameter} string syslog-facility
8164 Syslog facility to use if you're logging to syslog. Usually if you
8165 don't want to use @samp{mail}, you'll use local0..local7. Also other
8166 standard facilities are supported.
8167 Defaults to @samp{"mail"}.
8170 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-verbose?
8171 Log unsuccessful authentication attempts and the reasons why they
8173 Defaults to @samp{#f}.
8176 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-verbose-passwords?
8177 In case of password mismatches, log the attempted password. Valid
8178 values are no, plain and sha1. sha1 can be useful for detecting brute
8179 force password attempts vs. user simply trying the same password over
8180 and over again. You can also truncate the value to n chars by appending
8182 Defaults to @samp{#f}.
8185 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-debug?
8186 Even more verbose logging for debugging purposes. Shows for example
8188 Defaults to @samp{#f}.
8191 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-debug-passwords?
8192 In case of password mismatches, log the passwords and used scheme so
8193 the problem can be debugged. Enabling this also enables
8195 Defaults to @samp{#f}.
8198 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-debug?
8199 Enable mail process debugging. This can help you figure out why
8200 Dovecot isn't finding your mails.
8201 Defaults to @samp{#f}.
8204 @deftypevr {@code{dovecot-configuration} parameter} boolean verbose-ssl?
8205 Show protocol level SSL errors.
8206 Defaults to @samp{#f}.
8209 @deftypevr {@code{dovecot-configuration} parameter} string log-timestamp
8210 Prefix for each line written to log file. % codes are in
8212 Defaults to @samp{"\"%b %d %H:%M:%S \""}.
8215 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-log-format-elements
8216 List of elements we want to log. The elements which have a
8217 non-empty variable value are joined together to form a comma-separated
8221 @deftypevr {@code{dovecot-configuration} parameter} string login-log-format
8222 Login log format. %s contains @samp{login-log-format-elements}
8223 string, %$ contains the data we want to log.
8224 Defaults to @samp{"%$: %s"}.
8227 @deftypevr {@code{dovecot-configuration} parameter} string mail-log-prefix
8228 Log prefix for mail processes. See doc/wiki/Variables.txt for list
8229 of possible variables you can use.
8230 Defaults to @samp{"\"%s(%u): \""}.
8233 @deftypevr {@code{dovecot-configuration} parameter} string deliver-log-format
8234 Format to use for logging mail deliveries. You can use variables:
8237 Delivery status message (e.g. @samp{saved to INBOX})
8249 Defaults to @samp{"msgid=%m: %$"}.
8252 @deftypevr {@code{dovecot-configuration} parameter} string mail-location
8253 Location for users' mailboxes. The default is empty, which means
8254 that Dovecot tries to find the mailboxes automatically. This won't work
8255 if the user doesn't yet have any mail, so you should explicitly tell
8256 Dovecot the full location.
8258 If you're using mbox, giving a path to the INBOX
8259 file (e.g. /var/mail/%u) isn't enough. You'll also need to tell Dovecot
8260 where the other mailboxes are kept. This is called the "root mail
8261 directory", and it must be the first path given in the
8262 @samp{mail-location} setting.
8264 There are a few special variables you can use, eg.:
8270 user part in user@@domain, same as %u if there's no domain
8272 domain part in user@@domain, empty if there's no domain
8277 See doc/wiki/Variables.txt for full list. Some examples:
8279 @item maildir:~/Maildir
8280 @item mbox:~/mail:INBOX=/var/mail/%u
8281 @item mbox:/var/mail/%d/%1n/%n:INDEX=/var/indexes/%d/%1n/%
8283 Defaults to @samp{""}.
8286 @deftypevr {@code{dovecot-configuration} parameter} string mail-uid
8287 System user and group used to access mails. If you use multiple,
8288 userdb can override these by returning uid or gid fields. You can use
8289 either numbers or names. <doc/wiki/UserIds.txt>.
8290 Defaults to @samp{""}.
8293 @deftypevr {@code{dovecot-configuration} parameter} string mail-gid
8295 Defaults to @samp{""}.
8298 @deftypevr {@code{dovecot-configuration} parameter} string mail-privileged-group
8299 Group to enable temporarily for privileged operations. Currently
8300 this is used only with INBOX when either its initial creation or
8301 dotlocking fails. Typically this is set to "mail" to give access to
8303 Defaults to @samp{""}.
8306 @deftypevr {@code{dovecot-configuration} parameter} string mail-access-groups
8307 Grant access to these supplementary groups for mail processes.
8308 Typically these are used to set up access to shared mailboxes. Note
8309 that it may be dangerous to set these if users can create
8310 symlinks (e.g. if "mail" group is set here, ln -s /var/mail ~/mail/var
8311 could allow a user to delete others' mailboxes, or ln -s
8312 /secret/shared/box ~/mail/mybox would allow reading it).
8313 Defaults to @samp{""}.
8316 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-full-filesystem-access?
8317 Allow full filesystem access to clients. There's no access checks
8318 other than what the operating system does for the active UID/GID. It
8319 works with both maildir and mboxes, allowing you to prefix mailboxes
8320 names with e.g. /path/ or ~user/.
8321 Defaults to @samp{#f}.
8324 @deftypevr {@code{dovecot-configuration} parameter} boolean mmap-disable?
8325 Don't use mmap() at all. This is required if you store indexes to
8326 shared filesystems (NFS or clustered filesystem).
8327 Defaults to @samp{#f}.
8330 @deftypevr {@code{dovecot-configuration} parameter} boolean dotlock-use-excl?
8331 Rely on @samp{O_EXCL} to work when creating dotlock files. NFS
8332 supports @samp{O_EXCL} since version 3, so this should be safe to use
8333 nowadays by default.
8334 Defaults to @samp{#t}.
8337 @deftypevr {@code{dovecot-configuration} parameter} string mail-fsync
8338 When to use fsync() or fdatasync() calls:
8341 Whenever necessary to avoid losing important data
8343 Useful with e.g. NFS when write()s are delayed
8345 Never use it (best performance, but crashes can lose data).
8347 Defaults to @samp{"optimized"}.
8350 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-nfs-storage?
8351 Mail storage exists in NFS. Set this to yes to make Dovecot flush
8352 NFS caches whenever needed. If you're using only a single mail server
8354 Defaults to @samp{#f}.
8357 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-nfs-index?
8358 Mail index files also exist in NFS. Setting this to yes requires
8359 @samp{mmap-disable? #t} and @samp{fsync-disable? #f}.
8360 Defaults to @samp{#f}.
8363 @deftypevr {@code{dovecot-configuration} parameter} string lock-method
8364 Locking method for index files. Alternatives are fcntl, flock and
8365 dotlock. Dotlocking uses some tricks which may create more disk I/O
8366 than other locking methods. NFS users: flock doesn't work, remember to
8367 change @samp{mmap-disable}.
8368 Defaults to @samp{"fcntl"}.
8371 @deftypevr {@code{dovecot-configuration} parameter} file-name mail-temp-dir
8372 Directory in which LDA/LMTP temporarily stores incoming mails >128
8374 Defaults to @samp{"/tmp"}.
8377 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer first-valid-uid
8378 Valid UID range for users. This is mostly to make sure that users can't
8379 log in as daemons or other system users. Note that denying root logins is
8380 hardcoded to dovecot binary and can't be done even if @samp{first-valid-uid}
8382 Defaults to @samp{500}.
8385 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer last-valid-uid
8387 Defaults to @samp{0}.
8390 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer first-valid-gid
8391 Valid GID range for users. Users having non-valid GID as primary group ID
8392 aren't allowed to log in. If user belongs to supplementary groups with
8393 non-valid GIDs, those groups are not set.
8394 Defaults to @samp{1}.
8397 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer last-valid-gid
8399 Defaults to @samp{0}.
8402 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-max-keyword-length
8403 Maximum allowed length for mail keyword name. It's only forced when
8404 trying to create new keywords.
8405 Defaults to @samp{50}.
8408 @deftypevr {@code{dovecot-configuration} parameter} colon-separated-file-name-list valid-chroot-dirs
8409 List of directories under which chrooting is allowed for mail
8410 processes (i.e. /var/mail will allow chrooting to /var/mail/foo/bar
8411 too). This setting doesn't affect @samp{login-chroot}
8412 @samp{mail-chroot} or auth chroot settings. If this setting is empty,
8413 "/./" in home dirs are ignored. WARNING: Never add directories here
8414 which local users can modify, that may lead to root exploit. Usually
8415 this should be done only if you don't allow shell access for users.
8416 <doc/wiki/Chrooting.txt>.
8417 Defaults to @samp{()}.
8420 @deftypevr {@code{dovecot-configuration} parameter} string mail-chroot
8421 Default chroot directory for mail processes. This can be overridden
8422 for specific users in user database by giving /./ in user's home
8423 directory (e.g. /home/./user chroots into /home). Note that usually
8424 there is no real need to do chrooting, Dovecot doesn't allow users to
8425 access files outside their mail directory anyway. If your home
8426 directories are prefixed with the chroot directory, append "/." to
8427 @samp{mail-chroot}. <doc/wiki/Chrooting.txt>.
8428 Defaults to @samp{""}.
8431 @deftypevr {@code{dovecot-configuration} parameter} file-name auth-socket-path
8432 UNIX socket path to master authentication server to find users.
8433 This is used by imap (for shared users) and lda.
8434 Defaults to @samp{"/var/run/dovecot/auth-userdb"}.
8437 @deftypevr {@code{dovecot-configuration} parameter} file-name mail-plugin-dir
8438 Directory where to look up mail plugins.
8439 Defaults to @samp{"/usr/lib/dovecot"}.
8442 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mail-plugins
8443 List of plugins to load for all services. Plugins specific to IMAP,
8444 LDA, etc. are added to this list in their own .conf files.
8445 Defaults to @samp{()}.
8448 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-cache-min-mail-count
8449 The minimum number of mails in a mailbox before updates are done to
8450 cache file. This allows optimizing Dovecot's behavior to do less disk
8451 writes at the cost of more disk reads.
8452 Defaults to @samp{0}.
8455 @deftypevr {@code{dovecot-configuration} parameter} string mailbox-idle-check-interval
8456 When IDLE command is running, mailbox is checked once in a while to
8457 see if there are any new mails or other changes. This setting defines
8458 the minimum time to wait between those checks. Dovecot can also use
8459 dnotify, inotify and kqueue to find out immediately when changes
8461 Defaults to @samp{"30 secs"}.
8464 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-save-crlf?
8465 Save mails with CR+LF instead of plain LF. This makes sending those
8466 mails take less CPU, especially with sendfile() syscall with Linux and
8467 FreeBSD. But it also creates a bit more disk I/O which may just make it
8468 slower. Also note that if other software reads the mboxes/maildirs,
8469 they may handle the extra CRs wrong and cause problems.
8470 Defaults to @samp{#f}.
8473 @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-stat-dirs?
8474 By default LIST command returns all entries in maildir beginning
8475 with a dot. Enabling this option makes Dovecot return only entries
8476 which are directories. This is done by stat()ing each entry, so it
8477 causes more disk I/O.
8478 (For systems setting struct @samp{dirent->d_type} this check is free
8479 and it's done always regardless of this setting).
8480 Defaults to @samp{#f}.
8483 @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-copy-with-hardlinks?
8484 When copying a message, do it with hard links whenever possible.
8485 This makes the performance much better, and it's unlikely to have any
8487 Defaults to @samp{#t}.
8490 @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-very-dirty-syncs?
8491 Assume Dovecot is the only MUA accessing Maildir: Scan cur/
8492 directory only when its mtime changes unexpectedly or when we can't find
8494 Defaults to @samp{#f}.
8497 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mbox-read-locks
8498 Which locking methods to use for locking mbox. There are four
8503 Create <mailbox>.lock file. This is the oldest and most NFS-safe
8504 solution. If you want to use /var/mail/ like directory, the users will
8505 need write access to that directory.
8507 Same as dotlock, but if it fails because of permissions or because there
8508 isn't enough disk space, just skip it.
8510 Use this if possible. Works with NFS too if lockd is used.
8512 May not exist in all systems. Doesn't work with NFS.
8514 May not exist in all systems. Doesn't work with NFS.
8517 You can use multiple locking methods; if you do the order they're declared
8518 in is important to avoid deadlocks if other MTAs/MUAs are using multiple
8519 locking methods as well. Some operating systems don't allow using some of
8520 them simultaneously.
8523 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mbox-write-locks
8527 @deftypevr {@code{dovecot-configuration} parameter} string mbox-lock-timeout
8528 Maximum time to wait for lock (all of them) before aborting.
8529 Defaults to @samp{"5 mins"}.
8532 @deftypevr {@code{dovecot-configuration} parameter} string mbox-dotlock-change-timeout
8533 If dotlock exists but the mailbox isn't modified in any way,
8534 override the lock file after this much time.
8535 Defaults to @samp{"2 mins"}.
8538 @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-dirty-syncs?
8539 When mbox changes unexpectedly we have to fully read it to find out
8540 what changed. If the mbox is large this can take a long time. Since
8541 the change is usually just a newly appended mail, it'd be faster to
8542 simply read the new mails. If this setting is enabled, Dovecot does
8543 this but still safely fallbacks to re-reading the whole mbox file
8544 whenever something in mbox isn't how it's expected to be. The only real
8545 downside to this setting is that if some other MUA changes message
8546 flags, Dovecot doesn't notice it immediately. Note that a full sync is
8547 done with SELECT, EXAMINE, EXPUNGE and CHECK commands.
8548 Defaults to @samp{#t}.
8551 @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-very-dirty-syncs?
8552 Like @samp{mbox-dirty-syncs}, but don't do full syncs even with SELECT,
8553 EXAMINE, EXPUNGE or CHECK commands. If this is set,
8554 @samp{mbox-dirty-syncs} is ignored.
8555 Defaults to @samp{#f}.
8558 @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-lazy-writes?
8559 Delay writing mbox headers until doing a full write sync (EXPUNGE
8560 and CHECK commands and when closing the mailbox). This is especially
8561 useful for POP3 where clients often delete all mails. The downside is
8562 that our changes aren't immediately visible to other MUAs.
8563 Defaults to @samp{#t}.
8566 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mbox-min-index-size
8567 If mbox size is smaller than this (e.g. 100k), don't write index
8568 files. If an index file already exists it's still read, just not
8570 Defaults to @samp{0}.
8573 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mdbox-rotate-size
8574 Maximum dbox file size until it's rotated.
8575 Defaults to @samp{2000000}.
8578 @deftypevr {@code{dovecot-configuration} parameter} string mdbox-rotate-interval
8579 Maximum dbox file age until it's rotated. Typically in days. Day
8580 begins from midnight, so 1d = today, 2d = yesterday, etc. 0 = check
8582 Defaults to @samp{"1d"}.
8585 @deftypevr {@code{dovecot-configuration} parameter} boolean mdbox-preallocate-space?
8586 When creating new mdbox files, immediately preallocate their size to
8587 @samp{mdbox-rotate-size}. This setting currently works only in Linux
8588 with some filesystems (ext4, xfs).
8589 Defaults to @samp{#f}.
8592 @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-dir
8593 sdbox and mdbox support saving mail attachments to external files,
8594 which also allows single instance storage for them. Other backends
8595 don't support this for now.
8597 WARNING: This feature hasn't been tested much yet. Use at your own risk.
8599 Directory root where to store mail attachments. Disabled, if empty.
8600 Defaults to @samp{""}.
8603 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-attachment-min-size
8604 Attachments smaller than this aren't saved externally. It's also
8605 possible to write a plugin to disable saving specific attachments
8607 Defaults to @samp{128000}.
8610 @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-fs
8611 Filesystem backend to use for saving attachments:
8614 No SiS done by Dovecot (but this might help FS's own deduplication)
8616 SiS with immediate byte-by-byte comparison during saving
8617 @item sis-queue posix
8618 SiS with delayed comparison and deduplication.
8620 Defaults to @samp{"sis posix"}.
8623 @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-hash
8624 Hash format to use in attachment filenames. You can add any text and
8625 variables: @code{%@{md4@}}, @code{%@{md5@}}, @code{%@{sha1@}},
8626 @code{%@{sha256@}}, @code{%@{sha512@}}, @code{%@{size@}}. Variables can be
8627 truncated, e.g. @code{%@{sha256:80@}} returns only first 80 bits.
8628 Defaults to @samp{"%@{sha1@}"}.
8631 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-process-limit
8633 Defaults to @samp{100}.
8636 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-client-limit
8638 Defaults to @samp{1000}.
8641 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-vsz-limit
8642 Default VSZ (virtual memory size) limit for service processes.
8643 This is mainly intended to catch and kill processes that leak memory
8644 before they eat up everything.
8645 Defaults to @samp{256000000}.
8648 @deftypevr {@code{dovecot-configuration} parameter} string default-login-user
8649 Login user is internally used by login processes. This is the most
8650 untrusted user in Dovecot system. It shouldn't have access to anything
8652 Defaults to @samp{"dovenull"}.
8655 @deftypevr {@code{dovecot-configuration} parameter} string default-internal-user
8656 Internal user is used by unprivileged processes. It should be
8657 separate from login user, so that login processes can't disturb other
8659 Defaults to @samp{"dovecot"}.
8662 @deftypevr {@code{dovecot-configuration} parameter} string ssl?
8663 SSL/TLS support: yes, no, required. <doc/wiki/SSL.txt>.
8664 Defaults to @samp{"required"}.
8667 @deftypevr {@code{dovecot-configuration} parameter} string ssl-cert
8668 PEM encoded X.509 SSL/TLS certificate (public key).
8669 Defaults to @samp{"</etc/dovecot/default.pem"}.
8672 @deftypevr {@code{dovecot-configuration} parameter} string ssl-key
8673 PEM encoded SSL/TLS private key. The key is opened before
8674 dropping root privileges, so keep the key file unreadable by anyone but
8676 Defaults to @samp{"</etc/dovecot/private/default.pem"}.
8679 @deftypevr {@code{dovecot-configuration} parameter} string ssl-key-password
8680 If key file is password protected, give the password here.
8681 Alternatively give it when starting dovecot with -p parameter. Since
8682 this file is often world-readable, you may want to place this setting
8683 instead to a different.
8684 Defaults to @samp{""}.
8687 @deftypevr {@code{dovecot-configuration} parameter} string ssl-ca
8688 PEM encoded trusted certificate authority. Set this only if you
8689 intend to use @samp{ssl-verify-client-cert? #t}. The file should
8690 contain the CA certificate(s) followed by the matching
8691 CRL(s). (e.g. @samp{ssl-ca </etc/ssl/certs/ca.pem}).
8692 Defaults to @samp{""}.
8695 @deftypevr {@code{dovecot-configuration} parameter} boolean ssl-require-crl?
8696 Require that CRL check succeeds for client certificates.
8697 Defaults to @samp{#t}.
8700 @deftypevr {@code{dovecot-configuration} parameter} boolean ssl-verify-client-cert?
8701 Request client to send a certificate. If you also want to require
8702 it, set @samp{auth-ssl-require-client-cert? #t} in auth section.
8703 Defaults to @samp{#f}.
8706 @deftypevr {@code{dovecot-configuration} parameter} string ssl-cert-username-field
8707 Which field from certificate to use for username. commonName and
8708 x500UniqueIdentifier are the usual choices. You'll also need to set
8709 @samp{auth-ssl-username-from-cert? #t}.
8710 Defaults to @samp{"commonName"}.
8713 @deftypevr {@code{dovecot-configuration} parameter} hours ssl-parameters-regenerate
8714 How often to regenerate the SSL parameters file. Generation is
8715 quite CPU intensive operation. The value is in hours, 0 disables
8716 regeneration entirely.
8717 Defaults to @samp{168}.
8720 @deftypevr {@code{dovecot-configuration} parameter} string ssl-protocols
8721 SSL protocols to use.
8722 Defaults to @samp{"!SSLv2"}.
8725 @deftypevr {@code{dovecot-configuration} parameter} string ssl-cipher-list
8727 Defaults to @samp{"ALL:!LOW:!SSLv2:!EXP:!aNULL"}.
8730 @deftypevr {@code{dovecot-configuration} parameter} string ssl-crypto-device
8731 SSL crypto device to use, for valid values run "openssl engine".
8732 Defaults to @samp{""}.
8735 @deftypevr {@code{dovecot-configuration} parameter} string postmaster-address
8736 Address to use when sending rejection mails.
8737 Default is postmaster@@<your domain>. %d expands to recipient domain.
8738 Defaults to @samp{""}.
8741 @deftypevr {@code{dovecot-configuration} parameter} string hostname
8742 Hostname to use in various parts of sent mails (e.g. in Message-Id)
8743 and in LMTP replies. Default is the system's real hostname@@domain.
8744 Defaults to @samp{""}.
8747 @deftypevr {@code{dovecot-configuration} parameter} boolean quota-full-tempfail?
8748 If user is over quota, return with temporary failure instead of
8750 Defaults to @samp{#f}.
8753 @deftypevr {@code{dovecot-configuration} parameter} file-name sendmail-path
8754 Binary to use for sending mails.
8755 Defaults to @samp{"/usr/sbin/sendmail"}.
8758 @deftypevr {@code{dovecot-configuration} parameter} string submission-host
8759 If non-empty, send mails via this SMTP host[:port] instead of
8761 Defaults to @samp{""}.
8764 @deftypevr {@code{dovecot-configuration} parameter} string rejection-subject
8765 Subject: header to use for rejection mails. You can use the same
8766 variables as for @samp{rejection-reason} below.
8767 Defaults to @samp{"Rejected: %s"}.
8770 @deftypevr {@code{dovecot-configuration} parameter} string rejection-reason
8771 Human readable error message for rejection mails. You can use
8784 Defaults to @samp{"Your message to <%t> was automatically rejected:%n%r"}.
8787 @deftypevr {@code{dovecot-configuration} parameter} string recipient-delimiter
8788 Delimiter character between local-part and detail in email
8790 Defaults to @samp{"+"}.
8793 @deftypevr {@code{dovecot-configuration} parameter} string lda-original-recipient-header
8794 Header where the original recipient address (SMTP's RCPT TO:
8795 address) is taken from if not available elsewhere. With dovecot-lda -a
8796 parameter overrides this. A commonly used header for this is
8798 Defaults to @samp{""}.
8801 @deftypevr {@code{dovecot-configuration} parameter} boolean lda-mailbox-autocreate?
8802 Should saving a mail to a nonexistent mailbox automatically create
8804 Defaults to @samp{#f}.
8807 @deftypevr {@code{dovecot-configuration} parameter} boolean lda-mailbox-autosubscribe?
8808 Should automatically created mailboxes be also automatically
8810 Defaults to @samp{#f}.
8813 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer imap-max-line-length
8814 Maximum IMAP command line length. Some clients generate very long
8815 command lines with huge mailboxes, so you may need to raise this if you
8816 get "Too long argument" or "IMAP command line too large" errors
8818 Defaults to @samp{64000}.
8821 @deftypevr {@code{dovecot-configuration} parameter} string imap-logout-format
8822 IMAP logout format string:
8825 total number of bytes read from client
8827 total number of bytes sent to client.
8829 Defaults to @samp{"in=%i out=%o"}.
8832 @deftypevr {@code{dovecot-configuration} parameter} string imap-capability
8833 Override the IMAP CAPABILITY response. If the value begins with '+',
8834 add the given capabilities on top of the defaults (e.g. +XFOO XBAR).
8835 Defaults to @samp{""}.
8838 @deftypevr {@code{dovecot-configuration} parameter} string imap-idle-notify-interval
8839 How long to wait between "OK Still here" notifications when client
8841 Defaults to @samp{"2 mins"}.
8844 @deftypevr {@code{dovecot-configuration} parameter} string imap-id-send
8845 ID field names and values to send to clients. Using * as the value
8846 makes Dovecot use the default value. The following fields have default
8847 values currently: name, version, os, os-version, support-url,
8849 Defaults to @samp{""}.
8852 @deftypevr {@code{dovecot-configuration} parameter} string imap-id-log
8853 ID fields sent by client to log. * means everything.
8854 Defaults to @samp{""}.
8857 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list imap-client-workarounds
8858 Workarounds for various client bugs:
8862 Send EXISTS/RECENT new mail notifications only when replying to NOOP and
8863 CHECK commands. Some clients ignore them otherwise, for example OSX
8864 Mail (<v2.1). Outlook Express breaks more badly though, without this it
8865 may show user "Message no longer in server" errors. Note that OE6
8866 still breaks even with this workaround if synchronization is set to
8869 @item tb-extra-mailbox-sep
8870 Thunderbird gets somehow confused with LAYOUT=fs (mbox and dbox) and
8871 adds extra @samp{/} suffixes to mailbox names. This option causes Dovecot to
8872 ignore the extra @samp{/} instead of treating it as invalid mailbox name.
8875 Show \Noselect flags for LSUB replies with LAYOUT=fs (e.g. mbox).
8876 This makes Thunderbird realize they aren't selectable and show them
8877 greyed out, instead of only later giving "not selectable" popup error.
8879 Defaults to @samp{()}.
8882 @deftypevr {@code{dovecot-configuration} parameter} string imap-urlauth-host
8883 Host allowed in URLAUTH URLs sent by client. "*" allows all.
8884 Defaults to @samp{""}.
8888 Whew! Lots of configuration options. The nice thing about it though is
8889 that GuixSD has a complete interface to Dovecot's configuration
8890 language. This allows not only a nice way to declare configurations,
8891 but also offers reflective capabilities as well: users can write code to
8892 inspect and transform configurations from within Scheme.
8894 However, it could be that you just want to get a @code{dovecot.conf} up
8895 and running. In that case, you can pass an
8896 @code{opaque-dovecot-configuration} as the @code{#:config} paramter to
8897 @code{dovecot-service}. As its name indicates, an opaque configuration
8898 does not have easy reflective capabilities.
8900 Available @code{opaque-dovecot-configuration} fields are:
8902 @deftypevr {@code{opaque-dovecot-configuration} parameter} package dovecot
8903 The dovecot package.
8906 @deftypevr {@code{opaque-dovecot-configuration} parameter} string string
8907 The contents of the @code{dovecot.conf}, as a string.
8910 For example, if your @code{dovecot.conf} is just the empty string, you
8911 could instantiate a dovecot service like this:
8914 (dovecot-service #:config
8915 (opaque-dovecot-configuration
8920 @subsubsection Web Services
8922 The @code{(gnu services web)} module provides the following service:
8924 @deffn {Scheme Procedure} nginx-service [#:nginx nginx] @
8925 [#:log-directory ``/var/log/nginx''] @
8926 [#:run-directory ``/var/run/nginx''] @
8929 Return a service that runs @var{nginx}, the nginx web server.
8931 The nginx daemon loads its runtime configuration from @var{config-file}.
8932 Log files are written to @var{log-directory} and temporary runtime data
8933 files are written to @var{run-directory}. For proper operation, these
8934 arguments should match what is in @var{config-file} to ensure that the
8935 directories are created when the service is activated.
8939 @node Various Services
8940 @subsubsection Various Services
8942 The @code{(gnu services lirc)} module provides the following service.
8944 @deffn {Scheme Procedure} lirc-service [#:lirc lirc] @
8945 [#:device #f] [#:driver #f] [#:config-file #f] @
8946 [#:extra-options '()]
8947 Return a service that runs @url{http://www.lirc.org,LIRC}, a daemon that
8948 decodes infrared signals from remote controls.
8950 Optionally, @var{device}, @var{driver} and @var{config-file}
8951 (configuration file name) may be specified. See @command{lircd} manual
8954 Finally, @var{extra-options} is a list of additional command-line options
8955 passed to @command{lircd}.
8959 @node Setuid Programs
8960 @subsection Setuid Programs
8962 @cindex setuid programs
8963 Some programs need to run with ``root'' privileges, even when they are
8964 launched by unprivileged users. A notorious example is the
8965 @command{passwd} program, which users can run to change their
8966 password, and which needs to access the @file{/etc/passwd} and
8967 @file{/etc/shadow} files---something normally restricted to root, for
8968 obvious security reasons. To address that, these executables are
8969 @dfn{setuid-root}, meaning that they always run with root privileges
8970 (@pxref{How Change Persona,,, libc, The GNU C Library Reference Manual},
8971 for more info about the setuid mechanism.)
8973 The store itself @emph{cannot} contain setuid programs: that would be a
8974 security issue since any user on the system can write derivations that
8975 populate the store (@pxref{The Store}). Thus, a different mechanism is
8976 used: instead of changing the setuid bit directly on files that are in
8977 the store, we let the system administrator @emph{declare} which programs
8978 should be setuid root.
8980 The @code{setuid-programs} field of an @code{operating-system}
8981 declaration contains a list of G-expressions denoting the names of
8982 programs to be setuid-root (@pxref{Using the Configuration System}).
8983 For instance, the @command{passwd} program, which is part of the Shadow
8984 package, can be designated by this G-expression (@pxref{G-Expressions}):
8987 #~(string-append #$shadow "/bin/passwd")
8990 A default set of setuid programs is defined by the
8991 @code{%setuid-programs} variable of the @code{(gnu system)} module.
8993 @defvr {Scheme Variable} %setuid-programs
8994 A list of G-expressions denoting common programs that are setuid-root.
8996 The list includes commands such as @command{passwd}, @command{ping},
8997 @command{su}, and @command{sudo}.
9000 Under the hood, the actual setuid programs are created in the
9001 @file{/run/setuid-programs} directory at system activation time. The
9002 files in this directory refer to the ``real'' binaries, which are in the
9005 @node X.509 Certificates
9006 @subsection X.509 Certificates
9008 @cindex HTTPS, certificates
9009 @cindex X.509 certificates
9011 Web servers available over HTTPS (that is, HTTP over the transport-layer
9012 security mechanism, TLS) send client programs an @dfn{X.509 certificate}
9013 that the client can then use to @emph{authenticate} the server. To do
9014 that, clients verify that the server's certificate is signed by a
9015 so-called @dfn{certificate authority} (CA). But to verify the CA's
9016 signature, clients must have first acquired the CA's certificate.
9018 Web browsers such as GNU@tie{}IceCat include their own set of CA
9019 certificates, such that they are able to verify CA signatures
9022 However, most other programs that can talk HTTPS---@command{wget},
9023 @command{git}, @command{w3m}, etc.---need to be told where CA
9024 certificates can be found.
9026 @cindex @code{nss-certs}
9027 In GuixSD, this is done by adding a package that provides certificates
9028 to the @code{packages} field of the @code{operating-system} declaration
9029 (@pxref{operating-system Reference}). GuixSD includes one such package,
9030 @code{nss-certs}, which is a set of CA certificates provided as part of
9031 Mozilla's Network Security Services.
9033 Note that it is @emph{not} part of @var{%base-packages}, so you need to
9034 explicitly add it. The @file{/etc/ssl/certs} directory, which is where
9035 most applications and libraries look for certificates by default, points
9036 to the certificates installed globally.
9038 Unprivileged users can also install their own certificate package in
9039 their profile. A number of environment variables need to be defined so
9040 that applications and libraries know where to find them. Namely, the
9041 OpenSSL library honors the @code{SSL_CERT_DIR} and @code{SSL_CERT_FILE}
9042 variables. Some applications add their own environment variables; for
9043 instance, the Git version control system honors the certificate bundle
9044 pointed to by the @code{GIT_SSL_CAINFO} environment variable.
9047 @node Name Service Switch
9048 @subsection Name Service Switch
9050 @cindex name service switch
9052 The @code{(gnu system nss)} module provides bindings to the
9053 configuration file of libc's @dfn{name service switch} or @dfn{NSS}
9054 (@pxref{NSS Configuration File,,, libc, The GNU C Library Reference
9055 Manual}). In a nutshell, the NSS is a mechanism that allows libc to be
9056 extended with new ``name'' lookup methods for system databases, which
9057 includes host names, service names, user accounts, and more (@pxref{Name
9058 Service Switch, System Databases and Name Service Switch,, libc, The GNU
9059 C Library Reference Manual}).
9061 The NSS configuration specifies, for each system database, which lookup
9062 method is to be used, and how the various methods are chained
9063 together---for instance, under which circumstances NSS should try the
9064 next method in the list. The NSS configuration is given in the
9065 @code{name-service-switch} field of @code{operating-system} declarations
9066 (@pxref{operating-system Reference, @code{name-service-switch}}).
9069 @cindex .local, host name lookup
9070 As an example, the declaration below configures the NSS to use the
9071 @uref{http://0pointer.de/lennart/projects/nss-mdns/, @code{nss-mdns}
9072 back-end}, which supports host name lookups over multicast DNS (mDNS)
9073 for host names ending in @code{.local}:
9076 (name-service-switch
9077 (hosts (list %files ;first, check /etc/hosts
9079 ;; If the above did not succeed, try
9080 ;; with 'mdns_minimal'.
9082 (name "mdns_minimal")
9084 ;; 'mdns_minimal' is authoritative for
9085 ;; '.local'. When it returns "not found",
9086 ;; no need to try the next methods.
9087 (reaction (lookup-specification
9088 (not-found => return))))
9090 ;; Then fall back to DNS.
9094 ;; Finally, try with the "full" 'mdns'.
9099 Don't worry: the @code{%mdns-host-lookup-nss} variable (see below)
9100 contains this configuration, so you won't have to type it if all you
9101 want is to have @code{.local} host lookup working.
9103 Note that, in this case, in addition to setting the
9104 @code{name-service-switch} of the @code{operating-system} declaration,
9105 you also need to use @code{avahi-service} (@pxref{Networking Services,
9106 @code{avahi-service}}), or @var{%desktop-services}, which includes it
9107 (@pxref{Desktop Services}). Doing this makes @code{nss-mdns} accessible
9108 to the name service cache daemon (@pxref{Base Services,
9109 @code{nscd-service}}).
9111 For convenience, the following variables provide typical NSS
9114 @defvr {Scheme Variable} %default-nss
9115 This is the default name service switch configuration, a
9116 @code{name-service-switch} object.
9119 @defvr {Scheme Variable} %mdns-host-lookup-nss
9120 This is the name service switch configuration with support for host name
9121 lookup over multicast DNS (mDNS) for host names ending in @code{.local}.
9124 The reference for name service switch configuration is given below. It
9125 is a direct mapping of the C library's configuration file format, so
9126 please refer to the C library manual for more information (@pxref{NSS
9127 Configuration File,,, libc, The GNU C Library Reference Manual}).
9128 Compared to libc's NSS configuration file format, it has the advantage
9129 not only of adding this warm parenthetic feel that we like, but also
9130 static checks: you'll know about syntax errors and typos as soon as you
9131 run @command{guix system}.
9133 @deftp {Data Type} name-service-switch
9135 This is the data type representation the configuration of libc's name
9136 service switch (NSS). Each field below represents one of the supported
9153 The system databases handled by the NSS. Each of these fields must be a
9154 list of @code{<name-service>} objects (see below.)
9158 @deftp {Data Type} name-service
9160 This is the data type representing an actual name service and the
9161 associated lookup action.
9165 A string denoting the name service (@pxref{Services in the NSS
9166 configuration,,, libc, The GNU C Library Reference Manual}).
9168 Note that name services listed here must be visible to nscd. This is
9169 achieved by passing the @code{#:name-services} argument to
9170 @code{nscd-service} the list of packages providing the needed name
9171 services (@pxref{Base Services, @code{nscd-service}}).
9174 An action specified using the @code{lookup-specification} macro
9175 (@pxref{Actions in the NSS configuration,,, libc, The GNU C Library
9176 Reference Manual}). For example:
9179 (lookup-specification (unavailable => continue)
9180 (success => return))
9185 @node Initial RAM Disk
9186 @subsection Initial RAM Disk
9188 @cindex initial RAM disk (initrd)
9189 @cindex initrd (initial RAM disk)
9190 For bootstrapping purposes, the Linux-Libre kernel is passed an
9191 @dfn{initial RAM disk}, or @dfn{initrd}. An initrd contains a temporary
9192 root file system, as well as an initialization script. The latter is
9193 responsible for mounting the real root file system, and for loading any
9194 kernel modules that may be needed to achieve that.
9196 The @code{initrd} field of an @code{operating-system} declaration allows
9197 you to specify which initrd you would like to use. The @code{(gnu
9198 system linux-initrd)} module provides two ways to build an initrd: the
9199 high-level @code{base-initrd} procedure, and the low-level
9200 @code{expression->initrd} procedure.
9202 The @code{base-initrd} procedure is intended to cover most common uses.
9203 For example, if you want to add a bunch of kernel modules to be loaded
9204 at boot time, you can define the @code{initrd} field of the operating
9205 system declaration like this:
9208 (initrd (lambda (file-systems . rest)
9209 ;; Create a standard initrd that has modules "foo.ko"
9210 ;; and "bar.ko", as well as their dependencies, in
9211 ;; addition to the modules available by default.
9212 (apply base-initrd file-systems
9213 #:extra-modules '("foo" "bar")
9217 The @code{base-initrd} procedure also handles common use cases that
9218 involves using the system as a QEMU guest, or as a ``live'' system whose
9219 root file system is volatile.
9221 The initial RAM disk produced by @code{base-initrd} honors several
9222 options passed on the Linux kernel command line (that is, arguments
9223 passed @i{via} GRUB's @code{linux} command, or with QEMU's
9224 @code{-append} option), notably:
9227 @item --load=@var{boot}
9228 Tell the initial RAM disk to load @var{boot}, a file containing a Scheme
9229 program, once it has mounted the root file system.
9231 GuixSD uses this option to yield control to a boot program that runs the
9232 service activation programs and then spawns the GNU@tie{}Shepherd, the
9233 initialization system.
9235 @item --root=@var{root}
9236 Mount @var{root} as the root file system. @var{root} can be a device
9237 device name like @code{/dev/sda1}, a partition label, or a partition
9240 @item --system=@var{system}
9241 Have @file{/run/booted-system} and @file{/run/current-system} point to
9244 @item modprobe.blacklist=@var{modules}@dots{}
9245 @cindex module, black-listing
9246 @cindex black list, of kernel modules
9247 Instruct the initial RAM disk as well as the @command{modprobe} command
9248 (from the kmod package) to refuse to load @var{modules}. @var{modules}
9249 must be a comma-separated list of module names---e.g.,
9250 @code{usbkbd,9pnet}.
9253 Start a read-eval-print loop (REPL) from the initial RAM disk before it
9254 tries to load kernel modules and to mount the root file system. Our
9255 marketing team calls it @dfn{boot-to-Guile}. The Schemer in you will
9256 love it. @xref{Using Guile Interactively,,, guile, GNU Guile Reference
9257 Manual}, for more information on Guile's REPL.
9261 Now that you know all the features that initial RAM disks produced by
9262 @code{base-initrd} provide, here is how to use it and customize it
9265 @deffn {Monadic Procedure} base-initrd @var{file-systems} @
9266 [#:qemu-networking? #f] [#:virtio? #t] [#:volatile-root? #f] @
9267 [#:extra-modules '()] [#:mapped-devices '()]
9268 Return a monadic derivation that builds a generic initrd. @var{file-systems} is
9269 a list of file-systems to be mounted by the initrd, possibly in addition to
9270 the root file system specified on the kernel command line via @code{--root}.
9271 @var{mapped-devices} is a list of device mappings to realize before
9272 @var{file-systems} are mounted (@pxref{Mapped Devices}).
9274 When @var{qemu-networking?} is true, set up networking with the standard QEMU
9275 parameters. When @var{virtio?} is true, load additional modules so the initrd can
9276 be used as a QEMU guest with para-virtualized I/O drivers.
9278 When @var{volatile-root?} is true, the root file system is writable but any changes
9281 The initrd is automatically populated with all the kernel modules necessary
9282 for @var{file-systems} and for the given options. However, additional kernel
9283 modules can be listed in @var{extra-modules}. They will be added to the initrd, and
9284 loaded at boot time in the order in which they appear.
9287 Needless to say, the initrds we produce and use embed a
9288 statically-linked Guile, and the initialization program is a Guile
9289 program. That gives a lot of flexibility. The
9290 @code{expression->initrd} procedure builds such an initrd, given the
9291 program to run in that initrd.
9293 @deffn {Monadic Procedure} expression->initrd @var{exp} @
9294 [#:guile %guile-static-stripped] [#:name "guile-initrd"] @
9296 Return a derivation that builds a Linux initrd (a gzipped cpio archive)
9297 containing @var{guile} and that evaluates @var{exp}, a G-expression,
9298 upon booting. All the derivations referenced by @var{exp} are
9299 automatically copied to the initrd.
9301 @var{modules} is a list of Guile module names to be embedded in the
9305 @node GRUB Configuration
9306 @subsection GRUB Configuration
9311 The operating system uses GNU@tie{}GRUB as its boot loader
9312 (@pxref{Overview, overview of GRUB,, grub, GNU GRUB Manual}). It is
9313 configured using @code{grub-configuration} declarations. This data type
9314 is exported by the @code{(gnu system grub)} module, and described below.
9316 @deftp {Data Type} grub-configuration
9317 The type of a GRUB configuration declaration.
9322 This is a string denoting the boot device. It must be a device name
9323 understood by the @command{grub-install} command, such as
9324 @code{/dev/sda} or @code{(hd0)} (@pxref{Invoking grub-install,,, grub,
9327 @item @code{menu-entries} (default: @code{()})
9328 A possibly empty list of @code{menu-entry} objects (see below), denoting
9329 entries to appear in the GRUB boot menu, in addition to the current
9330 system entry and the entry pointing to previous system generations.
9332 @item @code{default-entry} (default: @code{0})
9333 The index of the default boot menu entry. Index 0 is for the current
9336 @item @code{timeout} (default: @code{5})
9337 The number of seconds to wait for keyboard input before booting. Set to
9338 0 to boot immediately, and to -1 to wait indefinitely.
9340 @item @code{theme} (default: @var{%default-theme})
9341 The @code{grub-theme} object describing the theme to use.
9346 Should you want to list additional boot menu entries @i{via} the
9347 @code{menu-entries} field above, you will need to create them with the
9348 @code{menu-entry} form:
9350 @deftp {Data Type} menu-entry
9351 The type of an entry in the GRUB boot menu.
9356 The label to show in the menu---e.g., @code{"GNU"}.
9359 The Linux kernel to boot.
9361 @item @code{linux-arguments} (default: @code{()})
9362 The list of extra Linux kernel command-line arguments---e.g.,
9363 @code{("console=ttyS0")}.
9366 A G-Expression or string denoting the file name of the initial RAM disk
9367 to use (@pxref{G-Expressions}).
9372 @c FIXME: Write documentation once it's stable.
9373 Themes are created using the @code{grub-theme} form, which is not
9376 @defvr {Scheme Variable} %default-theme
9377 This is the default GRUB theme used by the operating system, with a
9378 fancy background image displaying the GNU and Guix logos.
9382 @node Invoking guix system
9383 @subsection Invoking @code{guix system}
9385 Once you have written an operating system declaration, as seen in the
9386 previous section, it can be @dfn{instantiated} using the @command{guix
9387 system} command. The synopsis is:
9390 guix system @var{options}@dots{} @var{action} @var{file}
9393 @var{file} must be the name of a file containing an
9394 @code{operating-system} declaration. @var{action} specifies how the
9395 operating system is instantiated. Currently the following values are
9400 Build the operating system described in @var{file}, activate it, and
9401 switch to it@footnote{This action is usable only on systems already
9404 This effects all the configuration specified in @var{file}: user
9405 accounts, system services, global package list, setuid programs, etc.
9406 The command starts system services specified in @var{file} that are not
9407 currently running; if a service is currently running, it does not
9408 attempt to upgrade it since it would not be possible without stopping it
9411 It also adds a GRUB menu entry for the new OS configuration, and moves
9412 entries for older configurations to a submenu---unless
9413 @option{--no-grub} is passed.
9416 @c The paragraph below refers to the problem discussed at
9417 @c <http://lists.gnu.org/archive/html/guix-devel/2014-08/msg00057.html>.
9418 It is highly recommended to run @command{guix pull} once before you run
9419 @command{guix system reconfigure} for the first time (@pxref{Invoking
9420 guix pull}). Failing to do that you would see an older version of Guix
9421 once @command{reconfigure} has completed.
9425 Build the operating system's derivation, which includes all the
9426 configuration files and programs needed to boot and run the system.
9427 This action does not actually install anything.
9430 Populate the given directory with all the files necessary to run the
9431 operating system specified in @var{file}. This is useful for first-time
9432 installations of GuixSD. For instance:
9435 guix system init my-os-config.scm /mnt
9438 copies to @file{/mnt} all the store items required by the configuration
9439 specified in @file{my-os-config.scm}. This includes configuration
9440 files, packages, and so on. It also creates other essential files
9441 needed for the system to operate correctly---e.g., the @file{/etc},
9442 @file{/var}, and @file{/run} directories, and the @file{/bin/sh} file.
9444 This command also installs GRUB on the device specified in
9445 @file{my-os-config}, unless the @option{--no-grub} option was passed.
9448 @cindex virtual machine
9450 @anchor{guix system vm}
9451 Build a virtual machine that contain the operating system declared in
9452 @var{file}, and return a script to run that virtual machine (VM).
9453 Arguments given to the script are passed as is to QEMU.
9455 The VM shares its store with the host system.
9457 Additional file systems can be shared between the host and the VM using
9458 the @code{--share} and @code{--expose} command-line options: the former
9459 specifies a directory to be shared with write access, while the latter
9460 provides read-only access to the shared directory.
9462 The example below creates a VM in which the user's home directory is
9463 accessible read-only, and where the @file{/exchange} directory is a
9464 read-write mapping of the host's @file{$HOME/tmp}:
9467 guix system vm my-config.scm \
9468 --expose=$HOME --share=$HOME/tmp=/exchange
9471 On GNU/Linux, the default is to boot directly to the kernel; this has
9472 the advantage of requiring only a very tiny root disk image since the
9473 host's store can then be mounted.
9475 The @code{--full-boot} option forces a complete boot sequence, starting
9476 with the bootloader. This requires more disk space since a root image
9477 containing at least the kernel, initrd, and bootloader data files must
9478 be created. The @code{--image-size} option can be used to specify the
9483 Return a virtual machine or disk image of the operating system declared
9484 in @var{file} that stands alone. Use the @option{--image-size} option
9485 to specify the size of the image.
9487 When using @code{vm-image}, the returned image is in qcow2 format, which
9488 the QEMU emulator can efficiently use. @xref{Running GuixSD in a VM},
9489 for more information on how to run the image in a virtual machine.
9491 When using @code{disk-image}, a raw disk image is produced; it can be
9492 copied as is to a USB stick, for instance. Assuming @code{/dev/sdc} is
9493 the device corresponding to a USB stick, one can copy the image on it
9494 using the following command:
9497 # dd if=$(guix system disk-image my-os.scm) of=/dev/sdc
9501 Return a script to run the operating system declared in @var{file}
9502 within a container. Containers are a set of lightweight isolation
9503 mechanisms provided by the kernel Linux-libre. Containers are
9504 substantially less resource-demanding than full virtual machines since
9505 the kernel, shared objects, and other resources can be shared with the
9506 host system; this also means they provide thinner isolation.
9508 Currently, the script must be run as root in order to support more than
9509 a single user and group. The container shares its store with the host
9512 As with the @code{vm} action (@pxref{guix system vm}), additional file
9513 systems to be shared between the host and container can be specified
9514 using the @option{--share} and @option{--expose} options:
9517 guix system container my-config.scm \
9518 --expose=$HOME --share=$HOME/tmp=/exchange
9522 This option requires Linux-libre 3.19 or newer.
9527 @var{options} can contain any of the common build options (@pxref{Common
9528 Build Options}). In addition, @var{options} can contain one of the
9532 @item --system=@var{system}
9533 @itemx -s @var{system}
9534 Attempt to build for @var{system} instead of the host's system type.
9535 This works as per @command{guix build} (@pxref{Invoking guix build}).
9539 Return the derivation file name of the given operating system without
9542 @item --image-size=@var{size}
9543 For the @code{vm-image} and @code{disk-image} actions, create an image
9544 of the given @var{size}. @var{size} may be a number of bytes, or it may
9545 include a unit as a suffix (@pxref{Block size, size specifications,,
9546 coreutils, GNU Coreutils}).
9548 @item --on-error=@var{strategy}
9549 Apply @var{strategy} when an error occurs when reading @var{file}.
9550 @var{strategy} may be one of the following:
9553 @item nothing-special
9554 Report the error concisely and exit. This is the default strategy.
9557 Likewise, but also display a backtrace.
9560 Report the error and enter Guile's debugger. From there, you can run
9561 commands such as @code{,bt} to get a backtrace, @code{,locals} to
9562 display local variable values, and more generally inspect the program's
9563 state. @xref{Debug Commands,,, guile, GNU Guile Reference Manual}, for
9564 a list of available debugging commands.
9568 Note that all the actions above, except @code{build} and @code{init},
9569 rely on KVM support in the Linux-Libre kernel. Specifically, the
9570 machine should have hardware virtualization support, the corresponding
9571 KVM kernel module should be loaded, and the @file{/dev/kvm} device node
9572 must exist and be readable and writable by the user and by the daemon's
9575 Once you have built, configured, re-configured, and re-re-configured
9576 your GuixSD installation, you may find it useful to list the operating
9577 system generations available on disk---and that you can choose from the
9582 @item list-generations
9583 List a summary of each generation of the operating system available on
9584 disk, in a human-readable way. This is similar to the
9585 @option{--list-generations} option of @command{guix package}
9586 (@pxref{Invoking guix package}).
9588 Optionally, one can specify a pattern, with the same syntax that is used
9589 in @command{guix package --list-generations}, to restrict the list of
9590 generations displayed. For instance, the following command displays
9591 generations up to 10-day old:
9594 $ guix system list-generations 10d
9599 The @command{guix system} command has even more to offer! The following
9600 sub-commands allow you to visualize how your system services relate to
9603 @anchor{system-extension-graph}
9606 @item extension-graph
9607 Emit in Dot/Graphviz format to standard output the @dfn{service
9608 extension graph} of the operating system defined in @var{file}
9609 (@pxref{Service Composition}, for more information on service
9615 $ guix system extension-graph @var{file} | dot -Tpdf > services.pdf
9618 produces a PDF file showing the extension relations among services.
9620 @anchor{system-shepherd-graph}
9621 @item shepherd-graph
9622 Emit in Dot/Graphviz format to standard output the @dfn{dependency
9623 graph} of shepherd services of the operating system defined in
9624 @var{file}. @xref{Shepherd Services}, for more information and for an
9629 @node Running GuixSD in a VM
9630 @subsection Running GuixSD in a Virtual Machine
9632 One way to run GuixSD in a virtual machine (VM) is to build a GuixSD
9633 virtual machine image using @command{guix system vm-image}
9634 (@pxref{Invoking guix system}). The returned image is in qcow2 format,
9635 which the @uref{http://qemu.org/, QEMU emulator} can efficiently use.
9637 To run the image in QEMU, copy it out of the store (@pxref{The Store})
9638 and give yourself permission to write to the copy. When invoking QEMU,
9639 you must choose a system emulator that is suitable for your hardware
9640 platform. Here is a minimal QEMU invocation that will boot the result
9641 of @command{guix system vm-image} on x86_64 hardware:
9644 $ qemu-system-x86_64 \
9645 -net user -net nic,model=virtio \
9646 -enable-kvm -m 256 /tmp/qemu-image
9649 Here is what each of these options means:
9652 @item qemu-system-x86_64
9653 This specifies the hardware platform to emulate. This should match the
9657 Enable the unprivileged user-mode network stack. The guest OS can
9658 access the host but not vice versa. This is the simplest way to get the
9659 guest OS online. If you don't choose a network stack, the boot will
9662 @item -net nic,model=virtio
9663 You must create a network interface of a given model. If you don't
9664 create a NIC, the boot will fail. Assuming your hardware platform is
9665 x86_64, you can get a list of available NIC models by running
9666 @command{qemu-system-x86_64 -net nic,model=help}.
9669 If your system has hardware virtualization extensions, enabling the
9670 Linux kernel's virtual machine support (KVM) will make things run
9674 RAM available to the guest OS, in mebibytes. Defaults to 128@tie{}MiB,
9675 which may be insufficent for some operations.
9677 @item /tmp/qemu-image
9678 The file name of the qcow2 image.
9681 @node Defining Services
9682 @subsection Defining Services
9684 The previous sections show the available services and how one can combine
9685 them in an @code{operating-system} declaration. But how do we define
9686 them in the first place? And what is a service anyway?
9689 * Service Composition:: The model for composing services.
9690 * Service Types and Services:: Types and services.
9691 * Service Reference:: API reference.
9692 * Shepherd Services:: A particular type of service.
9695 @node Service Composition
9696 @subsubsection Service Composition
9700 Here we define a @dfn{service} as, broadly, something that extends the
9701 operating system's functionality. Often a service is a process---a
9702 @dfn{daemon}---started when the system boots: a secure shell server, a
9703 Web server, the Guix build daemon, etc. Sometimes a service is a daemon
9704 whose execution can be triggered by another daemon---e.g., an FTP server
9705 started by @command{inetd} or a D-Bus service activated by
9706 @command{dbus-daemon}. Occasionally, a service does not map to a
9707 daemon. For instance, the ``account'' service collects user accounts
9708 and makes sure they exist when the system runs; the ``udev'' service
9709 collects device management rules and makes them available to the eudev
9710 daemon; the @file{/etc} service populates the system's @file{/etc}
9713 @cindex service extensions
9714 GuixSD services are connected by @dfn{extensions}. For instance, the
9715 secure shell service @emph{extends} the Shepherd---GuixSD's
9716 initialization system, running as PID@tie{}1---by giving it the command
9717 lines to start and stop the secure shell daemon (@pxref{Networking
9718 Services, @code{lsh-service}}); the UPower service extends the D-Bus
9719 service by passing it its @file{.service} specification, and extends the
9720 udev service by passing it device management rules (@pxref{Desktop
9721 Services, @code{upower-service}}); the Guix daemon service extends the
9722 Shepherd by passing it the command lines to start and stop the daemon,
9723 and extends the account service by passing it a list of required build
9724 user accounts (@pxref{Base Services}).
9726 All in all, services and their ``extends'' relations form a directed
9727 acyclic graph (DAG). If we represent services as boxes and extensions
9728 as arrows, a typical system might provide something like this:
9730 @image{images/service-graph,,5in,Typical service extension graph.}
9732 @cindex system service
9733 At the bottom, we see the @dfn{system service}, which produces the
9734 directory containing everything to run and boot the system, as returned
9735 by the @command{guix system build} command. @xref{Service Reference},
9736 to learn about the other service types shown here.
9737 @xref{system-extension-graph, the @command{guix system extension-graph}
9738 command}, for information on how to generate this representation for a
9739 particular operating system definition.
9741 @cindex service types
9742 Technically, developers can define @dfn{service types} to express these
9743 relations. There can be any number of services of a given type on the
9744 system---for instance, a system running two instances of the GNU secure
9745 shell server (lsh) has two instances of @var{lsh-service-type}, with
9746 different parameters.
9748 The following section describes the programming interface for service
9751 @node Service Types and Services
9752 @subsubsection Service Types and Services
9754 A @dfn{service type} is a node in the DAG described above. Let us start
9755 with a simple example, the service type for the Guix build daemon
9756 (@pxref{Invoking guix-daemon}):
9759 (define guix-service-type
9763 (list (service-extension shepherd-root-service-type guix-shepherd-service)
9764 (service-extension account-service-type guix-accounts)
9765 (service-extension activation-service-type guix-activation)))))
9769 It defines a two things:
9773 A name, whose sole purpose is to make inspection and debugging easier.
9776 A list of @dfn{service extensions}, where each extension designates the
9777 target service type and a procedure that, given the service's
9778 parameters, returns a list of object to extend the service of that type.
9780 Every service type has at least one service extension. The only
9781 exception is the @dfn{boot service type}, which is the ultimate service.
9784 In this example, @var{guix-service-type} extends three services:
9787 @item shepherd-root-service-type
9788 The @var{guix-shepherd-service} procedure defines how the Shepherd
9789 service is extended. Namely, it returns a @code{<shepherd-service>}
9790 object that defines how @command{guix-daemon} is started and stopped
9791 (@pxref{Shepherd Services}).
9793 @item account-service-type
9794 This extension for this service is computed by @var{guix-accounts},
9795 which returns a list of @code{user-group} and @code{user-account}
9796 objects representing the build user accounts (@pxref{Invoking
9799 @item activation-service-type
9800 Here @var{guix-activation} is a procedure that returns a gexp, which is
9801 a code snippet to run at ``activation time''---e.g., when the service is
9805 A service of this type is instantiated like this:
9808 (service guix-service-type
9811 (use-substitutes? #f)))
9814 The second argument to the @code{service} form is a value representing
9815 the parameters of this specific service instance.
9816 @xref{guix-configuration-type, @code{guix-configuration}}, for
9817 information about the @code{guix-configuration} data type.
9819 @var{guix-service-type} is quite simple because it extends other
9820 services but is not extensible itself.
9822 @c @subsubsubsection Extensible Service Types
9824 The service type for an @emph{extensible} service looks like this:
9827 (define udev-service-type
9828 (service-type (name 'udev)
9830 (list (service-extension shepherd-root-service-type
9831 udev-shepherd-service)))
9833 (compose concatenate) ;concatenate the list of rules
9834 (extend (lambda (config rules)
9836 (($ <udev-configuration> udev initial-rules)
9838 (udev udev) ;the udev package to use
9839 (rules (append initial-rules rules)))))))))
9842 This is the service type for the
9843 @uref{https://wiki.gentoo.org/wiki/Project:Eudev, eudev device
9844 management daemon}. Compared to the previous example, in addition to an
9845 extension of @var{shepherd-root-service-type}, we see two new fields:
9849 This is the procedure to @dfn{compose} the list of extensions to
9850 services of this type.
9852 Services can extend the udev service by passing it lists of rules; we
9853 compose those extensions simply by concatenating them.
9856 This procedure defines how the service's value is @dfn{extended} with
9857 the composition of the extensions.
9859 Udev extensions are composed into a list of rules, but the udev service
9860 value is itself a @code{<udev-configuration>} record. So here, we
9861 extend that record by appending the list of rules it contains to the
9862 list of contributed rules.
9865 There can be only one instance of an extensible service type such as
9866 @var{udev-service-type}. If there were more, the
9867 @code{service-extension} specifications would be ambiguous.
9869 Still here? The next section provides a reference of the programming
9870 interface for services.
9872 @node Service Reference
9873 @subsubsection Service Reference
9875 We have seen an overview of service types (@pxref{Service Types and
9876 Services}). This section provides a reference on how to manipulate
9877 services and service types. This interface is provided by the
9878 @code{(gnu services)} module.
9880 @deffn {Scheme Procedure} service @var{type} @var{value}
9881 Return a new service of @var{type}, a @code{<service-type>} object (see
9882 below.) @var{value} can be any object; it represents the parameters of
9883 this particular service instance.
9886 @deffn {Scheme Procedure} service? @var{obj}
9887 Return true if @var{obj} is a service.
9890 @deffn {Scheme Procedure} service-kind @var{service}
9891 Return the type of @var{service}---i.e., a @code{<service-type>} object.
9894 @deffn {Scheme Procedure} service-parameters @var{service}
9895 Return the value associated with @var{service}. It represents its
9899 Here is an example of how a service is created and manipulated:
9903 (service nginx-service-type
9904 (nginx-configuration
9906 (log-directory log-directory)
9907 (run-directory run-directory)
9908 (file config-file))))
9913 (eq? (service-kind s) nginx-service-type)
9917 The @code{modify-services} form provides a handy way to change the
9918 parameters of some of the services of a list such as
9919 @var{%base-services} (@pxref{Base Services, @code{%base-services}}). Of
9920 course, you could always use standard list combinators such as
9921 @code{map} and @code{fold} to do that (@pxref{SRFI-1, List Library,,
9922 guile, GNU Guile Reference Manual}); @code{modify-services} simply
9923 provides a more concise form for this common pattern.
9925 @deffn {Scheme Syntax} modify-services @var{services} @
9926 (@var{type} @var{variable} => @var{body}) @dots{}
9928 Modify the services listed in @var{services} according to the given
9929 clauses. Each clause has the form:
9932 (@var{type} @var{variable} => @var{body})
9935 where @var{type} is a service type, such as @var{guix-service-type}, and
9936 @var{variable} is an identifier that is bound within @var{body} to the
9937 value of the service of that @var{type}. @xref{Using the Configuration
9938 System}, for an example.
9940 This is a shorthand for:
9943 (map (lambda (service) @dots{}) @var{services})
9947 Next comes the programming interface for service types. This is
9948 something you want to know when writing new service definitions, but not
9949 necessarily when simply looking for ways to customize your
9950 @code{operating-system} declaration.
9952 @deftp {Data Type} service-type
9953 @cindex service type
9954 This is the representation of a @dfn{service type} (@pxref{Service Types
9959 This is a symbol, used only to simplify inspection and debugging.
9961 @item @code{extensions}
9962 A non-empty list of @code{<service-extension>} objects (see below.)
9964 @item @code{compose} (default: @code{#f})
9965 If this is @code{#f}, then the service type denotes services that cannot
9966 be extended---i.e., services that do not receive ``values'' from other
9969 Otherwise, it must be a one-argument procedure. The procedure is called
9970 by @code{fold-services} and is passed a list of values collected from
9971 extensions. It must return a value that is a valid parameter value for
9972 the service instance.
9974 @item @code{extend} (default: @code{#f})
9975 If this is @code{#f}, services of this type cannot be extended.
9977 Otherwise, it must be a two-argument procedure: @code{fold-services}
9978 calls it, passing it the service's initial value as the first argument
9979 and the result of applying @code{compose} to the extension values as the
9983 @xref{Service Types and Services}, for examples.
9986 @deffn {Scheme Procedure} service-extension @var{target-type} @
9988 Return a new extension for services of type @var{target-type}.
9989 @var{compute} must be a one-argument procedure: @code{fold-services}
9990 calls it, passing it the value associated with the service that provides
9991 the extension; it must return a valid value for the target service.
9994 @deffn {Scheme Procedure} service-extension? @var{obj}
9995 Return true if @var{obj} is a service extension.
9998 At the core of the service abstraction lies the @code{fold-services}
9999 procedure, which is responsible for ``compiling'' a list of services
10000 down to a single directory that contains everything needed to boot and
10001 run the system---the directory shown by the @command{guix system build}
10002 command (@pxref{Invoking guix system}). In essence, it propagates
10003 service extensions down the service graph, updating each node parameters
10004 on the way, until it reaches the root node.
10006 @deffn {Scheme Procedure} fold-services @var{services} @
10007 [#:target-type @var{system-service-type}]
10008 Fold @var{services} by propagating their extensions down to the root of
10009 type @var{target-type}; return the root service adjusted accordingly.
10012 Lastly, the @code{(gnu services)} module also defines several essential
10013 service types, some of which are listed below.
10015 @defvr {Scheme Variable} system-service-type
10016 This is the root of the service graph. It produces the system directory
10017 as returned by the @command{guix system build} command.
10020 @defvr {Scheme Variable} boot-service-type
10021 The type of the ``boot service'', which produces the @dfn{boot script}.
10022 The boot script is what the initial RAM disk runs when booting.
10025 @defvr {Scheme Variable} etc-service-type
10026 The type of the @file{/etc} service. This service can be extended by
10027 passing it name/file tuples such as:
10030 (list `("issue" ,(plain-file "issue" "Welcome!\n")))
10033 In this example, the effect would be to add an @file{/etc/issue} file
10034 pointing to the given file.
10037 @defvr {Scheme Variable} setuid-program-service-type
10038 Type for the ``setuid-program service''. This service collects lists of
10039 executable file names, passed as gexps, and adds them to the set of
10040 setuid-root programs on the system (@pxref{Setuid Programs}).
10043 @defvr {Scheme Variable} profile-service-type
10044 Type of the service that populates the @dfn{system profile}---i.e., the
10045 programs under @file{/run/current-system/profile}. Other services can
10046 extend it by passing it lists of packages to add to the system profile.
10050 @node Shepherd Services
10051 @subsubsection Shepherd Services
10054 @cindex init system
10055 The @code{(gnu services shepherd)} module provides a way to define
10056 services managed by the GNU@tie{}Shepherd, which is the GuixSD
10057 initialization system---the first process that is started when the
10058 system boots, aka. PID@tie{}1 (@pxref{Introduction,,, shepherd, The GNU
10061 Services in the Shepherd can depend on each other. For instance, the
10062 SSH daemon may need to be started after the syslog daemon has been
10063 started, which in turn can only happen once all the file systems have
10064 been mounted. The simple operating system defined earlier (@pxref{Using
10065 the Configuration System}) results in a service graph like this:
10067 @image{images/shepherd-graph,,5in,Typical shepherd service graph.}
10069 You can actually generate such a graph for any operating system
10070 definition using the @command{guix system shepherd-graph} command
10071 (@pxref{system-shepherd-graph, @command{guix system shepherd-graph}}).
10073 The @var{%shepherd-root-service} is a service object representing
10074 PID@tie{}1, of type @var{shepherd-root-service-type}; it can be extended
10075 by passing it lists of @code{<shepherd-service>} objects.
10077 @deftp {Data Type} shepherd-service
10078 The data type representing a service managed by the Shepherd.
10081 @item @code{provision}
10082 This is a list of symbols denoting what the service provides.
10084 These are the names that may be passed to @command{herd start},
10085 @command{herd status}, and similar commands (@pxref{Invoking herd,,,
10086 shepherd, The GNU Shepherd Manual}). @xref{Slots of services, the
10087 @code{provides} slot,, shepherd, The GNU Shepherd Manual}, for details.
10089 @item @code{requirements} (default: @code{'()})
10090 List of symbols denoting the Shepherd services this one depends on.
10092 @item @code{respawn?} (default: @code{#t})
10093 Whether to restart the service when it stops, for instance when the
10094 underlying process dies.
10097 @itemx @code{stop} (default: @code{#~(const #f)})
10098 The @code{start} and @code{stop} fields refer to the Shepherd's
10099 facilities to start and stop processes (@pxref{Service De- and
10100 Constructors,,, shepherd, The GNU Shepherd Manual}). They are given as
10101 G-expressions that get expanded in the Shepherd configuration file
10102 (@pxref{G-Expressions}).
10104 @item @code{documentation}
10105 A documentation string, as shown when running:
10108 herd doc @var{service-name}
10111 where @var{service-name} is one of the symbols in @var{provision}
10112 (@pxref{Invoking herd,,, shepherd, The GNU Shepherd Manual}).
10114 @item @code{modules} (default: @var{%default-modules})
10115 This is the list of modules that must be in scope when @code{start} and
10116 @code{stop} are evaluated.
10118 @item @code{imported-modules} (default: @var{%default-imported-modules})
10119 This is the list of modules to import in the execution environment of
10125 @defvr {Scheme Variable} shepherd-root-service-type
10126 The service type for the Shepherd ``root service''---i.e., PID@tie{}1.
10128 This is the service type that extensions target when they want to create
10129 shepherd services (@pxref{Service Types and Services}, for an example).
10130 Each extension must pass a list of @code{<shepherd-service>}.
10133 @defvr {Scheme Variable} %shepherd-root-service
10134 This service represents PID@tie{}1.
10138 @node Installing Debugging Files
10139 @section Installing Debugging Files
10141 @cindex debugging files
10142 Program binaries, as produced by the GCC compilers for instance, are
10143 typically written in the ELF format, with a section containing
10144 @dfn{debugging information}. Debugging information is what allows the
10145 debugger, GDB, to map binary code to source code; it is required to
10146 debug a compiled program in good conditions.
10148 The problem with debugging information is that is takes up a fair amount
10149 of disk space. For example, debugging information for the GNU C Library
10150 weighs in at more than 60 MiB. Thus, as a user, keeping all the
10151 debugging info of all the installed programs is usually not an option.
10152 Yet, space savings should not come at the cost of an impediment to
10153 debugging---especially in the GNU system, which should make it easier
10154 for users to exert their computing freedom (@pxref{GNU Distribution}).
10156 Thankfully, the GNU Binary Utilities (Binutils) and GDB provide a
10157 mechanism that allows users to get the best of both worlds: debugging
10158 information can be stripped from the binaries and stored in separate
10159 files. GDB is then able to load debugging information from those files,
10160 when they are available (@pxref{Separate Debug Files,,, gdb, Debugging
10163 The GNU distribution takes advantage of this by storing debugging
10164 information in the @code{lib/debug} sub-directory of a separate package
10165 output unimaginatively called @code{debug} (@pxref{Packages with
10166 Multiple Outputs}). Users can choose to install the @code{debug} output
10167 of a package when they need it. For instance, the following command
10168 installs the debugging information for the GNU C Library and for GNU
10172 guix package -i glibc:debug guile:debug
10175 GDB must then be told to look for debug files in the user's profile, by
10176 setting the @code{debug-file-directory} variable (consider setting it
10177 from the @file{~/.gdbinit} file, @pxref{Startup,,, gdb, Debugging with
10181 (gdb) set debug-file-directory ~/.guix-profile/lib/debug
10184 From there on, GDB will pick up debugging information from the
10185 @code{.debug} files under @file{~/.guix-profile/lib/debug}.
10187 In addition, you will most likely want GDB to be able to show the source
10188 code being debugged. To do that, you will have to unpack the source
10189 code of the package of interest (obtained with @code{guix build
10190 --source}, @pxref{Invoking guix build}), and to point GDB to that source
10191 directory using the @code{directory} command (@pxref{Source Path,
10192 @code{directory},, gdb, Debugging with GDB}).
10194 @c XXX: keep me up-to-date
10195 The @code{debug} output mechanism in Guix is implemented by the
10196 @code{gnu-build-system} (@pxref{Build Systems}). Currently, it is
10197 opt-in---debugging information is available only for those packages
10198 whose definition explicitly declares a @code{debug} output. This may be
10199 changed to opt-out in the future, if our build farm servers can handle
10200 the load. To check whether a package has a @code{debug} output, use
10201 @command{guix package --list-available} (@pxref{Invoking guix package}).
10204 @node Security Updates
10205 @section Security Updates
10208 As of version @value{VERSION}, the feature described in this section is
10212 @cindex security updates
10213 Occasionally, important security vulnerabilities are discovered in core
10214 software packages and must be patched. Guix follows a functional
10215 package management discipline (@pxref{Introduction}), which implies
10216 that, when a package is changed, @emph{every package that depends on it}
10217 must be rebuilt. This can significantly slow down the deployment of
10218 fixes in core packages such as libc or Bash, since basically the whole
10219 distribution would need to be rebuilt. Using pre-built binaries helps
10220 (@pxref{Substitutes}), but deployment may still take more time than
10224 To address that, Guix implements @dfn{grafts}, a mechanism that allows
10225 for fast deployment of critical updates without the costs associated
10226 with a whole-distribution rebuild. The idea is to rebuild only the
10227 package that needs to be patched, and then to ``graft'' it onto packages
10228 explicitly installed by the user and that were previously referring to
10229 the original package. The cost of grafting is typically very low, and
10230 order of magnitudes lower than a full rebuild of the dependency chain.
10232 @cindex replacements of packages, for grafts
10233 For instance, suppose a security update needs to be applied to Bash.
10234 Guix developers will provide a package definition for the ``fixed''
10235 Bash, say @var{bash-fixed}, in the usual way (@pxref{Defining
10236 Packages}). Then, the original package definition is augmented with a
10237 @code{replacement} field pointing to the package containing the bug fix:
10244 (replacement bash-fixed)))
10247 From there on, any package depending directly or indirectly on Bash that
10248 is installed will automatically be ``rewritten'' to refer to
10249 @var{bash-fixed} instead of @var{bash}. This grafting process takes
10250 time proportional to the size of the package, but expect less than a
10251 minute for an ``average'' package on a recent machine.
10253 Currently, the graft and the package it replaces (@var{bash-fixed} and
10254 @var{bash} in the example above) must have the exact same @code{name}
10255 and @code{version} fields. This restriction mostly comes from the fact
10256 that grafting works by patching files, including binary files, directly.
10257 Other restrictions may apply: for instance, when adding a graft to a
10258 package providing a shared library, the original shared library and its
10259 replacement must have the same @code{SONAME} and be binary-compatible.
10262 @node Package Modules
10263 @section Package Modules
10265 From a programming viewpoint, the package definitions of the
10266 GNU distribution are provided by Guile modules in the @code{(gnu packages
10267 @dots{})} name space@footnote{Note that packages under the @code{(gnu
10268 packages @dots{})} module name space are not necessarily ``GNU
10269 packages''. This module naming scheme follows the usual Guile module
10270 naming convention: @code{gnu} means that these modules are distributed
10271 as part of the GNU system, and @code{packages} identifies modules that
10272 define packages.} (@pxref{Modules, Guile modules,, guile, GNU Guile
10273 Reference Manual}). For instance, the @code{(gnu packages emacs)}
10274 module exports a variable named @code{emacs}, which is bound to a
10275 @code{<package>} object (@pxref{Defining Packages}).
10277 The @code{(gnu packages @dots{})} module name space is
10278 automatically scanned for packages by the command-line tools. For
10279 instance, when running @code{guix package -i emacs}, all the @code{(gnu
10280 packages @dots{})} modules are scanned until one that exports a package
10281 object whose name is @code{emacs} is found. This package search
10282 facility is implemented in the @code{(gnu packages)} module.
10284 @cindex customization, of packages
10285 @cindex package module search path
10286 Users can store package definitions in modules with different
10287 names---e.g., @code{(my-packages emacs)}@footnote{Note that the file
10288 name and module name must match. For instance, the @code{(my-packages
10289 emacs)} module must be stored in a @file{my-packages/emacs.scm} file
10290 relative to the load path specified with @option{--load-path} or
10291 @code{GUIX_PACKAGE_PATH}. @xref{Modules and the File System,,,
10292 guile, GNU Guile Reference Manual}, for details.}. These package definitions
10293 will not be visible by default. Thus, users can invoke commands such as
10294 @command{guix package} and @command{guix build} have to be used with the
10295 @code{-e} option so that they know where to find the package. Better
10296 yet, they can use the
10297 @code{-L} option of these commands to make those modules visible
10298 (@pxref{Invoking guix build, @code{--load-path}}), or define the
10299 @code{GUIX_PACKAGE_PATH} environment variable. This environment
10300 variable makes it easy to extend or customize the distribution and is
10301 honored by all the user interfaces.
10303 @defvr {Environment Variable} GUIX_PACKAGE_PATH
10304 This is a colon-separated list of directories to search for package
10305 modules. Directories listed in this variable take precedence over the
10306 distribution's own modules.
10309 The distribution is fully @dfn{bootstrapped} and @dfn{self-contained}:
10310 each package is built based solely on other packages in the
10311 distribution. The root of this dependency graph is a small set of
10312 @dfn{bootstrap binaries}, provided by the @code{(gnu packages
10313 bootstrap)} module. For more information on bootstrapping,
10314 @pxref{Bootstrapping}.
10316 @node Packaging Guidelines
10317 @section Packaging Guidelines
10319 The GNU distribution is nascent and may well lack some of your favorite
10320 packages. This section describes how you can help make the distribution
10321 grow. @xref{Contributing}, for additional information on how you can
10324 Free software packages are usually distributed in the form of
10325 @dfn{source code tarballs}---typically @file{tar.gz} files that contain
10326 all the source files. Adding a package to the distribution means
10327 essentially two things: adding a @dfn{recipe} that describes how to
10328 build the package, including a list of other packages required to build
10329 it, and adding @dfn{package metadata} along with that recipe, such as a
10330 description and licensing information.
10332 In Guix all this information is embodied in @dfn{package definitions}.
10333 Package definitions provide a high-level view of the package. They are
10334 written using the syntax of the Scheme programming language; in fact,
10335 for each package we define a variable bound to the package definition,
10336 and export that variable from a module (@pxref{Package Modules}).
10337 However, in-depth Scheme knowledge is @emph{not} a prerequisite for
10338 creating packages. For more information on package definitions,
10339 @pxref{Defining Packages}.
10341 Once a package definition is in place, stored in a file in the Guix
10342 source tree, it can be tested using the @command{guix build} command
10343 (@pxref{Invoking guix build}). For example, assuming the new package is
10344 called @code{gnew}, you may run this command from the Guix build tree
10345 (@pxref{Running Guix Before It Is Installed}):
10348 ./pre-inst-env guix build gnew --keep-failed
10351 Using @code{--keep-failed} makes it easier to debug build failures since
10352 it provides access to the failed build tree. Another useful
10353 command-line option when debugging is @code{--log-file}, to access the
10356 If the package is unknown to the @command{guix} command, it may be that
10357 the source file contains a syntax error, or lacks a @code{define-public}
10358 clause to export the package variable. To figure it out, you may load
10359 the module from Guile to get more information about the actual error:
10362 ./pre-inst-env guile -c '(use-modules (gnu packages gnew))'
10365 Once your package builds correctly, please send us a patch
10366 (@pxref{Contributing}). Well, if you need help, we will be happy to
10367 help you too. Once the patch is committed in the Guix repository, the
10368 new package automatically gets built on the supported platforms by
10369 @url{http://hydra.gnu.org/jobset/gnu/master, our continuous integration
10372 @cindex substituter
10373 Users can obtain the new package definition simply by running
10374 @command{guix pull} (@pxref{Invoking guix pull}). When
10375 @code{hydra.gnu.org} is done building the package, installing the
10376 package automatically downloads binaries from there
10377 (@pxref{Substitutes}). The only place where human intervention is
10378 needed is to review and apply the patch.
10382 * Software Freedom:: What may go into the distribution.
10383 * Package Naming:: What's in a name?
10384 * Version Numbers:: When the name is not enough.
10385 * Synopses and Descriptions:: Helping users find the right package.
10386 * Python Modules:: Taming the snake.
10387 * Perl Modules:: Little pearls.
10388 * Fonts:: Fond of fonts.
10391 @node Software Freedom
10392 @subsection Software Freedom
10394 @c Adapted from http://www.gnu.org/philosophy/philosophy.html.
10396 The GNU operating system has been developed so that users can have
10397 freedom in their computing. GNU is @dfn{free software}, meaning that
10398 users have the @url{http://www.gnu.org/philosophy/free-sw.html,four
10399 essential freedoms}: to run the program, to study and change the program
10400 in source code form, to redistribute exact copies, and to distribute
10401 modified versions. Packages found in the GNU distribution provide only
10402 software that conveys these four freedoms.
10404 In addition, the GNU distribution follow the
10405 @url{http://www.gnu.org/distros/free-system-distribution-guidelines.html,free
10406 software distribution guidelines}. Among other things, these guidelines
10407 reject non-free firmware, recommendations of non-free software, and
10408 discuss ways to deal with trademarks and patents.
10410 Some packages contain a small and optional subset that violates the
10411 above guidelines, for instance because this subset is itself non-free
10412 code. When that happens, the offending items are removed with
10413 appropriate patches or code snippets in the package definition's
10414 @code{origin} form (@pxref{Defining Packages}). That way, @code{guix
10415 build --source} returns the ``freed'' source rather than the unmodified
10419 @node Package Naming
10420 @subsection Package Naming
10422 A package has actually two names associated with it:
10423 First, there is the name of the @emph{Scheme variable}, the one following
10424 @code{define-public}. By this name, the package can be made known in the
10425 Scheme code, for instance as input to another package. Second, there is
10426 the string in the @code{name} field of a package definition. This name
10427 is used by package management commands such as
10428 @command{guix package} and @command{guix build}.
10430 Both are usually the same and correspond to the lowercase conversion of
10431 the project name chosen upstream, with underscores replaced with
10432 hyphens. For instance, GNUnet is available as @code{gnunet}, and
10433 SDL_net as @code{sdl-net}.
10435 We do not add @code{lib} prefixes for library packages, unless these are
10436 already part of the official project name. But @pxref{Python
10437 Modules} and @ref{Perl Modules} for special rules concerning modules for
10438 the Python and Perl languages.
10440 Font package names are handled differently, @pxref{Fonts}.
10443 @node Version Numbers
10444 @subsection Version Numbers
10446 We usually package only the latest version of a given free software
10447 project. But sometimes, for instance for incompatible library versions,
10448 two (or more) versions of the same package are needed. These require
10449 different Scheme variable names. We use the name as defined
10450 in @ref{Package Naming}
10451 for the most recent version; previous versions use the same name, suffixed
10452 by @code{-} and the smallest prefix of the version number that may
10453 distinguish the two versions.
10455 The name inside the package definition is the same for all versions of a
10456 package and does not contain any version number.
10458 For instance, the versions 2.24.20 and 3.9.12 of GTK+ may be packaged as follows:
10461 (define-public gtk+
10466 (define-public gtk+-2
10469 (version "2.24.20")
10472 If we also wanted GTK+ 3.8.2, this would be packaged as
10474 (define-public gtk+-3.8
10481 @c See <https://lists.gnu.org/archive/html/guix-devel/2016-01/msg00425.html>,
10482 @c for a discussion of what follows.
10483 @cindex version number, for VCS snapshots
10484 Occasionally, we package snapshots of upstream's version control system
10485 (VCS) instead of formal releases. This should remain exceptional,
10486 because it is up to upstream developers to clarify what the stable
10487 release is. Yet, it is sometimes necessary. So, what should we put in
10488 the @code{version} field?
10490 Clearly, we need to make the commit identifier of the VCS snapshot
10491 visible in the version string, but we also need to make sure that the
10492 version string is monotonically increasing so that @command{guix package
10493 --upgrade} can determine which version is newer. Since commit
10494 identifiers, notably with Git, are not monotonically increasing, we add
10495 a revision number that we increase each time we upgrade to a newer
10496 snapshot. The resulting version string looks like this:
10501 | | `-- upstream commit ID
10503 | `--- Guix package revision
10505 latest upstream version
10508 It is a good idea to strip commit identifiers in the @code{version}
10509 field to, say, 7 digits. It avoids an aesthetic annoyance (assuming
10510 aesthetics have a role to play here) as well as problems related to OS
10511 limits such as the maximum shebang length (127 bytes for the Linux
10512 kernel.) It is best to use the full commit identifiers in
10513 @code{origin}s, though, to avoid ambiguities. A typical package
10514 definition may look like this:
10518 (let ((commit "c3f29bc928d5900971f65965feaae59e1272a3f7"))
10520 (version (string-append "0.9-1."
10521 (string-take commit 7)))
10524 (uri (git-reference
10525 (url "git://example.org/my-package.git")
10527 (sha256 (base32 "1mbikn@dots{}"))
10528 (file-name (string-append "my-package-" version
10534 @node Synopses and Descriptions
10535 @subsection Synopses and Descriptions
10537 As we have seen before, each package in GNU@tie{}Guix includes a
10538 synopsis and a description (@pxref{Defining Packages}). Synopses and
10539 descriptions are important: They are what @command{guix package
10540 --search} searches, and a crucial piece of information to help users
10541 determine whether a given package suits their needs. Consequently,
10542 packagers should pay attention to what goes into them.
10544 Synopses must start with a capital letter and must not end with a
10545 period. They must not start with ``a'' or ``the'', which usually does
10546 not bring anything; for instance, prefer ``File-frobbing tool'' over ``A
10547 tool that frobs files''. The synopsis should say what the package
10548 is---e.g., ``Core GNU utilities (file, text, shell)''---or what it is
10549 used for---e.g., the synopsis for GNU@tie{}grep is ``Print lines
10550 matching a pattern''.
10552 Keep in mind that the synopsis must be meaningful for a very wide
10553 audience. For example, ``Manipulate alignments in the SAM format''
10554 might make sense for a seasoned bioinformatics researcher, but might be
10555 fairly unhelpful or even misleading to a non-specialized audience. It
10556 is a good idea to come up with a synopsis that gives an idea of the
10557 application domain of the package. In this example, this might give
10558 something like ``Manipulate nucleotide sequence alignments'', which
10559 hopefully gives the user a better idea of whether this is what they are
10562 @cindex Texinfo markup, in package descriptions
10563 Descriptions should take between five and ten lines. Use full
10564 sentences, and avoid using acronyms without first introducing them.
10565 Descriptions can include Texinfo markup, which is useful to introduce
10566 ornaments such as @code{@@code} or @code{@@dfn}, bullet lists, or
10567 hyperlinks (@pxref{Overview,,, texinfo, GNU Texinfo}). However you
10568 should be careful when using some characters for example @samp{@@} and
10569 curly braces which are the basic special characters in Texinfo
10570 (@pxref{Special Characters,,, texinfo, GNU Texinfo}). User interfaces
10571 such as @command{guix package --show} take care of rendering it
10574 Synopses and descriptions are translated by volunteers
10575 @uref{http://translationproject.org/domain/guix-packages.html, at the
10576 Translation Project} so that as many users as possible can read them in
10577 their native language. User interfaces search them and display them in
10578 the language specified by the current locale.
10580 Translation is a lot of work so, as a packager, please pay even more
10581 attention to your synopses and descriptions as every change may entail
10582 additional work for translators. In order to help them, it is possible
10583 to make recommendations or instructions visible to them by inserting
10584 special comments like this (@pxref{xgettext Invocation,,, gettext, GNU
10588 ;; TRANSLATORS: "X11 resize-and-rotate" should not be translated.
10589 (description "ARandR is designed to provide a simple visual front end
10590 for the X11 resize-and-rotate (RandR) extension. @dots{}")
10594 @node Python Modules
10595 @subsection Python Modules
10597 We currently package Python 2 and Python 3, under the Scheme variable names
10598 @code{python-2} and @code{python} as explained in @ref{Version Numbers}.
10599 To avoid confusion and naming clashes with other programming languages, it
10600 seems desirable that the name of a package for a Python module contains
10601 the word @code{python}.
10603 Some modules are compatible with only one version of Python, others with both.
10604 If the package Foo compiles only with Python 3, we name it
10605 @code{python-foo}; if it compiles only with Python 2, we name it
10606 @code{python2-foo}. If it is compatible with both versions, we create two
10607 packages with the corresponding names.
10609 If a project already contains the word @code{python}, we drop this;
10610 for instance, the module python-dateutil is packaged under the names
10611 @code{python-dateutil} and @code{python2-dateutil}.
10615 @subsection Perl Modules
10617 Perl programs standing for themselves are named as any other package,
10618 using the lowercase upstream name.
10619 For Perl packages containing a single class, we use the lowercase class name,
10620 replace all occurrences of @code{::} by dashes and prepend the prefix
10622 So the class @code{XML::Parser} becomes @code{perl-xml-parser}.
10623 Modules containing several classes keep their lowercase upstream name and
10624 are also prepended by @code{perl-}. Such modules tend to have the word
10625 @code{perl} somewhere in their name, which gets dropped in favor of the
10626 prefix. For instance, @code{libwww-perl} becomes @code{perl-libwww}.
10632 For fonts that are in general not installed by a user for typesetting
10633 purposes, or that are distributed as part of a larger software package,
10634 we rely on the general packaging rules for software; for instance, this
10635 applies to the fonts delivered as part of the X.Org system or fonts that
10636 are part of TeX Live.
10638 To make it easier for a user to search for fonts, names for other packages
10639 containing only fonts are constructed as follows, independently of the
10640 upstream package name.
10642 The name of a package containing only one font family starts with
10643 @code{font-}; it is followed by the foundry name and a dash @code{-}
10644 if the foundry is known, and the font family name, in which spaces are
10645 replaced by dashes (and as usual, all upper case letters are transformed
10647 For example, the Gentium font family by SIL is packaged under the name
10648 @code{font-sil-gentium}.
10650 For a package containing several font families, the name of the collection
10651 is used in the place of the font family name.
10652 For instance, the Liberation fonts consist of three families,
10653 Liberation Sans, Liberation Serif and Liberation Mono.
10654 These could be packaged separately under the names
10655 @code{font-liberation-sans} and so on; but as they are distributed together
10656 under a common name, we prefer to package them together as
10657 @code{font-liberation}.
10659 In the case where several formats of the same font family or font collection
10660 are packaged separately, a short form of the format, prepended by a dash,
10661 is added to the package name. We use @code{-ttf} for TrueType fonts,
10662 @code{-otf} for OpenType fonts and @code{-type1} for PostScript Type 1
10667 @node Bootstrapping
10668 @section Bootstrapping
10670 @c Adapted from the ELS 2013 paper.
10672 @cindex bootstrapping
10674 Bootstrapping in our context refers to how the distribution gets built
10675 ``from nothing''. Remember that the build environment of a derivation
10676 contains nothing but its declared inputs (@pxref{Introduction}). So
10677 there's an obvious chicken-and-egg problem: how does the first package
10678 get built? How does the first compiler get compiled? Note that this is
10679 a question of interest only to the curious hacker, not to the regular
10680 user, so you can shamelessly skip this section if you consider yourself
10681 a ``regular user''.
10683 @cindex bootstrap binaries
10684 The GNU system is primarily made of C code, with libc at its core. The
10685 GNU build system itself assumes the availability of a Bourne shell and
10686 command-line tools provided by GNU Coreutils, Awk, Findutils, `sed', and
10687 `grep'. Furthermore, build programs---programs that run
10688 @code{./configure}, @code{make}, etc.---are written in Guile Scheme
10689 (@pxref{Derivations}). Consequently, to be able to build anything at
10690 all, from scratch, Guix relies on pre-built binaries of Guile, GCC,
10691 Binutils, libc, and the other packages mentioned above---the
10692 @dfn{bootstrap binaries}.
10694 These bootstrap binaries are ``taken for granted'', though we can also
10695 re-create them if needed (more on that later).
10697 @unnumberedsubsec Preparing to Use the Bootstrap Binaries
10699 @c As of Emacs 24.3, Info-mode displays the image, but since it's a
10700 @c large image, it's hard to scroll. Oh well.
10701 @image{images/bootstrap-graph,6in,,Dependency graph of the early bootstrap derivations}
10703 The figure above shows the very beginning of the dependency graph of the
10704 distribution, corresponding to the package definitions of the @code{(gnu
10705 packages bootstrap)} module. A similar figure can be generated with
10706 @command{guix graph} (@pxref{Invoking guix graph}), along the lines of:
10709 guix graph -t derivation \
10710 -e '(@@@@ (gnu packages bootstrap) %bootstrap-gcc)' \
10714 At this level of detail, things are
10715 slightly complex. First, Guile itself consists of an ELF executable,
10716 along with many source and compiled Scheme files that are dynamically
10717 loaded when it runs. This gets stored in the @file{guile-2.0.7.tar.xz}
10718 tarball shown in this graph. This tarball is part of Guix's ``source''
10719 distribution, and gets inserted into the store with @code{add-to-store}
10720 (@pxref{The Store}).
10722 But how do we write a derivation that unpacks this tarball and adds it
10723 to the store? To solve this problem, the @code{guile-bootstrap-2.0.drv}
10724 derivation---the first one that gets built---uses @code{bash} as its
10725 builder, which runs @code{build-bootstrap-guile.sh}, which in turn calls
10726 @code{tar} to unpack the tarball. Thus, @file{bash}, @file{tar},
10727 @file{xz}, and @file{mkdir} are statically-linked binaries, also part of
10728 the Guix source distribution, whose sole purpose is to allow the Guile
10729 tarball to be unpacked.
10731 Once @code{guile-bootstrap-2.0.drv} is built, we have a functioning
10732 Guile that can be used to run subsequent build programs. Its first task
10733 is to download tarballs containing the other pre-built binaries---this
10734 is what the @code{.tar.xz.drv} derivations do. Guix modules such as
10735 @code{ftp-client.scm} are used for this purpose. The
10736 @code{module-import.drv} derivations import those modules in a directory
10737 in the store, using the original layout. The
10738 @code{module-import-compiled.drv} derivations compile those modules, and
10739 write them in an output directory with the right layout. This
10740 corresponds to the @code{#:modules} argument of
10741 @code{build-expression->derivation} (@pxref{Derivations}).
10743 Finally, the various tarballs are unpacked by the
10744 derivations @code{gcc-bootstrap-0.drv}, @code{glibc-bootstrap-0.drv},
10745 etc., at which point we have a working C tool chain.
10748 @unnumberedsubsec Building the Build Tools
10750 Bootstrapping is complete when we have a full tool chain that does not
10751 depend on the pre-built bootstrap tools discussed above. This
10752 no-dependency requirement is verified by checking whether the files of
10753 the final tool chain contain references to the @file{/gnu/store}
10754 directories of the bootstrap inputs. The process that leads to this
10755 ``final'' tool chain is described by the package definitions found in
10756 the @code{(gnu packages commencement)} module.
10758 The @command{guix graph} command allows us to ``zoom out'' compared to
10759 the graph above, by looking at the level of package objects instead of
10760 individual derivations---remember that a package may translate to
10761 several derivations, typically one derivation to download its source,
10762 one to build the Guile modules it needs, and one to actually build the
10763 package from source. The command:
10766 guix graph -t bag \
10767 -e '(@@@@ (gnu packages commencement)
10768 glibc-final-with-bootstrap-bash)' | dot -Tps > t.ps
10772 produces the dependency graph leading to the ``final'' C
10773 library@footnote{You may notice the @code{glibc-intermediate} label,
10774 suggesting that it is not @emph{quite} final, but as a good
10775 approximation, we will consider it final.}, depicted below.
10777 @image{images/bootstrap-packages,6in,,Dependency graph of the early packages}
10779 @c See <http://lists.gnu.org/archive/html/gnu-system-discuss/2012-10/msg00000.html>.
10780 The first tool that gets built with the bootstrap binaries is
10781 GNU@tie{}Make---noted @code{make-boot0} above---which is a prerequisite
10782 for all the following packages. From there Findutils and Diffutils get
10785 Then come the first-stage Binutils and GCC, built as pseudo cross
10786 tools---i.e., with @code{--target} equal to @code{--host}. They are
10787 used to build libc. Thanks to this cross-build trick, this libc is
10788 guaranteed not to hold any reference to the initial tool chain.
10790 From there the final Binutils and GCC (not shown above) are built.
10792 from the final Binutils, and links programs against the just-built libc.
10793 This tool chain is used to build the other packages used by Guix and by
10794 the GNU Build System: Guile, Bash, Coreutils, etc.
10796 And voilà! At this point we have the complete set of build tools that
10797 the GNU Build System expects. These are in the @code{%final-inputs}
10798 variable of the @code{(gnu packages commencement)} module, and are
10799 implicitly used by any package that uses @code{gnu-build-system}
10800 (@pxref{Build Systems, @code{gnu-build-system}}).
10803 @unnumberedsubsec Building the Bootstrap Binaries
10805 Because the final tool chain does not depend on the bootstrap binaries,
10806 those rarely need to be updated. Nevertheless, it is useful to have an
10807 automated way to produce them, should an update occur, and this is what
10808 the @code{(gnu packages make-bootstrap)} module provides.
10810 The following command builds the tarballs containing the bootstrap
10811 binaries (Guile, Binutils, GCC, libc, and a tarball containing a mixture
10812 of Coreutils and other basic command-line tools):
10815 guix build bootstrap-tarballs
10818 The generated tarballs are those that should be referred to in the
10819 @code{(gnu packages bootstrap)} module mentioned at the beginning of
10822 Still here? Then perhaps by now you've started to wonder: when do we
10823 reach a fixed point? That is an interesting question! The answer is
10824 unknown, but if you would like to investigate further (and have
10825 significant computational and storage resources to do so), then let us
10829 @section Porting to a New Platform
10831 As discussed above, the GNU distribution is self-contained, and
10832 self-containment is achieved by relying on pre-built ``bootstrap
10833 binaries'' (@pxref{Bootstrapping}). These binaries are specific to an
10834 operating system kernel, CPU architecture, and application binary
10835 interface (ABI). Thus, to port the distribution to a platform that is
10836 not yet supported, one must build those bootstrap binaries, and update
10837 the @code{(gnu packages bootstrap)} module to use them on that platform.
10839 Fortunately, Guix can @emph{cross compile} those bootstrap binaries.
10840 When everything goes well, and assuming the GNU tool chain supports the
10841 target platform, this can be as simple as running a command like this
10845 guix build --target=armv5tel-linux-gnueabi bootstrap-tarballs
10848 For this to work, the @code{glibc-dynamic-linker} procedure in
10849 @code{(gnu packages bootstrap)} must be augmented to return the right
10850 file name for libc's dynamic linker on that platform; likewise,
10851 @code{system->linux-architecture} in @code{(gnu packages linux)} must be
10852 taught about the new platform.
10854 Once these are built, the @code{(gnu packages bootstrap)} module needs
10855 to be updated to refer to these binaries on the target platform. That
10856 is, the hashes and URLs of the bootstrap tarballs for the new platform
10857 must be added alongside those of the currently supported platforms. The
10858 bootstrap Guile tarball is treated specially: it is expected to be
10859 available locally, and @file{gnu-system.am} has rules do download it for
10860 the supported architectures; a rule for the new platform must be added
10863 In practice, there may be some complications. First, it may be that the
10864 extended GNU triplet that specifies an ABI (like the @code{eabi} suffix
10865 above) is not recognized by all the GNU tools. Typically, glibc
10866 recognizes some of these, whereas GCC uses an extra @code{--with-abi}
10867 configure flag (see @code{gcc.scm} for examples of how to handle this).
10868 Second, some of the required packages could fail to build for that
10869 platform. Lastly, the generated binaries could be broken for some
10872 @c *********************************************************************
10873 @include contributing.texi
10875 @c *********************************************************************
10876 @node Acknowledgments
10877 @chapter Acknowledgments
10879 Guix is based on the @uref{http://nixos.org/nix/, Nix package manager},
10880 which was designed and
10881 implemented by Eelco Dolstra, with contributions from other people (see
10882 the @file{nix/AUTHORS} file in Guix.) Nix pioneered functional package
10883 management, and promoted unprecedented features, such as transactional
10884 package upgrades and rollbacks, per-user profiles, and referentially
10885 transparent build processes. Without this work, Guix would not exist.
10887 The Nix-based software distributions, Nixpkgs and NixOS, have also been
10888 an inspiration for Guix.
10890 GNU@tie{}Guix itself is a collective work with contributions from a
10891 number of people. See the @file{AUTHORS} file in Guix for more
10892 information on these fine people. The @file{THANKS} file lists people
10893 who have helped by reporting bugs, taking care of the infrastructure,
10894 providing artwork and themes, making suggestions, and more---thank you!
10897 @c *********************************************************************
10898 @node GNU Free Documentation License
10899 @appendix GNU Free Documentation License
10901 @include fdl-1.3.texi
10903 @c *********************************************************************
10904 @node Concept Index
10905 @unnumbered Concept Index
10908 @node Programming Index
10909 @unnumbered Programming Index
10910 @syncodeindex tp fn
10911 @syncodeindex vr fn
10916 @c Local Variables:
10917 @c ispell-local-dictionary: "american";