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{} 2014, 2015, 2016 Alex Kost@*
17 Copyright @copyright{} 2015, 2016 Mathieu Lirzin@*
18 Copyright @copyright{} 2014 Pierre-Antoine Rault@*
19 Copyright @copyright{} 2015 Taylan Ulrich Bayırlı/Kammer@*
20 Copyright @copyright{} 2015, 2016 Leo Famulari@*
21 Copyright @copyright{} 2015, 2016 Ricardo Wurmus@*
22 Copyright @copyright{} 2016 Ben Woodcroft@*
23 Copyright @copyright{} 2016 Chris Marusich@*
24 Copyright @copyright{} 2016 Efraim Flashner
26 Permission is granted to copy, distribute and/or modify this document
27 under the terms of the GNU Free Documentation License, Version 1.3 or
28 any later version published by the Free Software Foundation; with no
29 Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A
30 copy of the license is included in the section entitled ``GNU Free
31 Documentation License''.
34 @dircategory System administration
36 * Guix: (guix). Manage installed software and system configuration.
37 * guix package: (guix)Invoking guix package. Installing, removing, and upgrading packages.
38 * guix build: (guix)Invoking guix build. Building packages.
39 * guix gc: (guix)Invoking guix gc. Reclaiming unused disk space.
40 * guix pull: (guix)Invoking guix pull. Update the list of available packages.
41 * guix system: (guix)Invoking guix system. Manage the operating system configuration.
44 @dircategory Software development
46 * guix environment: (guix)Invoking guix environment. Building development environments with Guix.
51 * Guix user interface: (guix)Emacs Interface. Package management from the comfort of Emacs.
56 @title GNU Guix Reference Manual
57 @subtitle Using the GNU Guix Functional Package Manager
58 @author The GNU Guix Developers
61 @vskip 0pt plus 1filll
62 Edition @value{EDITION} @*
70 @c *********************************************************************
74 This document describes GNU Guix version @value{VERSION}, a functional
75 package management tool written for the GNU system.
78 * Introduction:: What is Guix about?
79 * Installation:: Installing Guix.
80 * Package Management:: Package installation, upgrade, etc.
81 * Emacs Interface:: Using Guix from Emacs.
82 * Programming Interface:: Using Guix in Scheme.
83 * Utilities:: Package management commands.
84 * GNU Distribution:: Software for your friendly GNU system.
85 * Contributing:: Your help needed!
87 * Acknowledgments:: Thanks!
88 * GNU Free Documentation License:: The license of this manual.
89 * Concept Index:: Concepts.
90 * Programming Index:: Data types, functions, and variables.
93 --- The Detailed Node Listing ---
97 * Binary Installation:: Getting Guix running in no time!
98 * Requirements:: Software needed to build and run Guix.
99 * Running the Test Suite:: Testing Guix.
100 * Setting Up the Daemon:: Preparing the build daemon's environment.
101 * Invoking guix-daemon:: Running the build daemon.
102 * Application Setup:: Application-specific setup.
104 Setting Up the Daemon
106 * Build Environment Setup:: Preparing the isolated build environment.
107 * Daemon Offload Setup:: Offloading builds to remote machines.
111 * Features:: How Guix will make your life brighter.
112 * Invoking guix package:: Package installation, removal, etc.
113 * Substitutes:: Downloading pre-built binaries.
114 * Packages with Multiple Outputs:: Single source package, multiple outputs.
115 * Invoking guix gc:: Running the garbage collector.
116 * Invoking guix pull:: Fetching the latest Guix and distribution.
117 * Invoking guix archive:: Exporting and importing store files.
121 * Initial Setup: Emacs Initial Setup. Preparing @file{~/.emacs}.
122 * Package Management: Emacs Package Management. Managing packages and generations.
123 * Licenses: Emacs Licenses. Interface for licenses of Guix packages.
124 * Package Source Locations: Emacs Package Locations. Interface for package location files.
125 * Popup Interface: Emacs Popup Interface. Magit-like interface for guix commands.
126 * Prettify Mode: Emacs Prettify. Abbreviating @file{/gnu/store/@dots{}} file names.
127 * Build Log Mode: Emacs Build Log. Highlighting Guix build logs.
128 * Completions: Emacs Completions. Completing @command{guix} shell command.
129 * Development: Emacs Development. Tools for Guix developers.
130 * Hydra: Emacs Hydra. Interface for Guix build farm.
132 Programming Interface
134 * Defining Packages:: Defining new packages.
135 * Build Systems:: Specifying how packages are built.
136 * The Store:: Manipulating the package store.
137 * Derivations:: Low-level interface to package derivations.
138 * The Store Monad:: Purely functional interface to the store.
139 * G-Expressions:: Manipulating build expressions.
143 * package Reference:: The package data type.
144 * origin Reference:: The origin data type.
148 * Invoking guix build:: Building packages from the command line.
149 * Invoking guix edit:: Editing package definitions.
150 * Invoking guix download:: Downloading a file and printing its hash.
151 * Invoking guix hash:: Computing the cryptographic hash of a file.
152 * Invoking guix import:: Importing package definitions.
153 * Invoking guix refresh:: Updating package definitions.
154 * Invoking guix lint:: Finding errors in package definitions.
155 * Invoking guix size:: Profiling disk usage.
156 * Invoking guix graph:: Visualizing the graph of packages.
157 * Invoking guix environment:: Setting up development environments.
158 * Invoking guix publish:: Sharing substitutes.
159 * Invoking guix challenge:: Challenging substitute servers.
160 * Invoking guix container:: Process isolation.
162 Invoking @command{guix build}
164 * Common Build Options:: Build options for most commands.
165 * Package Transformation Options:: Creating variants of packages.
166 * Additional Build Options:: Options specific to 'guix build'.
170 * System Installation:: Installing the whole operating system.
171 * System Configuration:: Configuring the operating system.
172 * Installing Debugging Files:: Feeding the debugger.
173 * Security Updates:: Deploying security fixes quickly.
174 * Package Modules:: Packages from the programmer's viewpoint.
175 * Packaging Guidelines:: Growing the distribution.
176 * Bootstrapping:: GNU/Linux built from scratch.
177 * Porting:: Targeting another platform or kernel.
181 * Limitations:: What you can expect.
182 * Hardware Considerations:: Supported hardware.
183 * USB Stick Installation:: Preparing the installation medium.
184 * Preparing for Installation:: Networking, partitioning, etc.
185 * Proceeding with the Installation:: The real thing.
186 * Building the Installation Image:: How this comes to be.
190 * Using the Configuration System:: Customizing your GNU system.
191 * operating-system Reference:: Detail of operating-system declarations.
192 * File Systems:: Configuring file system mounts.
193 * Mapped Devices:: Block device extra processing.
194 * User Accounts:: Specifying user accounts.
195 * Locales:: Language and cultural convention settings.
196 * Services:: Specifying system services.
197 * Setuid Programs:: Programs running with root privileges.
198 * X.509 Certificates:: Authenticating HTTPS servers.
199 * Name Service Switch:: Configuring libc's name service switch.
200 * Initial RAM Disk:: Linux-Libre bootstrapping.
201 * GRUB Configuration:: Configuring the boot loader.
202 * Invoking guix system:: Instantiating a system configuration.
203 * Running GuixSD in a VM:: How to run GuixSD in a virtual machine.
204 * Defining Services:: Adding new service definitions.
208 * Base Services:: Essential system services.
209 * Scheduled Job Execution:: The mcron service.
210 * Networking Services:: Network setup, SSH daemon, etc.
211 * X Window:: Graphical display.
212 * Desktop Services:: D-Bus and desktop services.
213 * Database Services:: SQL databases.
214 * Mail Services:: IMAP, POP3, SMTP, and all that.
215 * Web Services:: Web servers.
216 * Various Services:: Other services.
220 * Service Composition:: The model for composing services.
221 * Service Types and Services:: Types and services.
222 * Service Reference:: API reference.
223 * Shepherd Services:: A particular type of service.
227 * Software Freedom:: What may go into the distribution.
228 * Package Naming:: What's in a name?
229 * Version Numbers:: When the name is not enough.
230 * Synopses and Descriptions:: Helping users find the right package.
231 * Python Modules:: Taming the snake.
232 * Perl Modules:: Little pearls.
233 * Java Packages:: Coffee break.
234 * Fonts:: Fond of fonts.
238 * Building from Git:: The latest and greatest.
239 * Running Guix Before It Is Installed:: Hacker tricks.
240 * The Perfect Setup:: The right tools.
241 * Coding Style:: Hygiene of the contributor.
242 * Submitting Patches:: Share your work.
246 * Programming Paradigm:: How to compose your elements.
247 * Modules:: Where to store your code?
248 * Data Types and Pattern Matching:: Implementing data structures.
249 * Formatting Code:: Writing conventions.
254 @c *********************************************************************
256 @chapter Introduction
259 GNU Guix@footnote{``Guix'' is pronounced like ``geeks'', or ``ɡiːks''
260 using the international phonetic alphabet (IPA).} is a package
261 management tool for the GNU system. Guix makes it easy for unprivileged
262 users to install, upgrade, or remove packages, to roll back to a
263 previous package set, to build packages from source, and generally
264 assists with the creation and maintenance of software environments.
266 @cindex user interfaces
267 Guix provides a command-line package management interface
268 (@pxref{Invoking guix package}), a set of command-line utilities
269 (@pxref{Utilities}), a visual user interface in Emacs (@pxref{Emacs
270 Interface}), as well as Scheme programming interfaces
271 (@pxref{Programming Interface}).
273 Its @dfn{build daemon} is responsible for building packages on behalf of
274 users (@pxref{Setting Up the Daemon}) and for downloading pre-built
275 binaries from authorized sources (@pxref{Substitutes}).
277 @cindex extensibility of the distribution
278 @cindex customization of packages
279 Guix includes package definitions for many GNU and non-GNU packages, all
280 of which @uref{https://www.gnu.org/philosophy/free-sw.html, respect the
281 user's computing freedom}. It is @emph{extensible}: users can write
282 their own package definitions (@pxref{Defining Packages}) and make them
283 available as independent package modules (@pxref{Package Modules}). It
284 is also @emph{customizable}: users can @emph{derive} specialized package
285 definitions from existing ones, including from the command line
286 (@pxref{Package Transformation Options}).
288 @cindex Guix System Distribution
290 You can install GNU@tie{}Guix on top of an existing GNU/Linux system
291 where it complements the available tools without interference
292 (@pxref{Installation}), or you can use it as part of the standalone
293 @dfn{Guix System Distribution} or GuixSD (@pxref{GNU Distribution}).
294 With GNU@tie{}GuixSD, you @emph{declare} all aspects of the operating
295 system configuration and Guix takes care of instantiating the
296 configuration in a transactional, reproducible, and stateless fashion
297 (@pxref{System Configuration}).
299 @cindex functional package management
300 Under the hood, Guix implements the @dfn{functional package management}
301 discipline pioneered by Nix (@pxref{Acknowledgments}).
302 In Guix, the package build and installation process is seen
303 as a @emph{function}, in the mathematical sense. That function takes inputs,
304 such as build scripts, a compiler, and libraries, and
305 returns an installed package. As a pure function, its result depends
306 solely on its inputs---for instance, it cannot refer to software or
307 scripts that were not explicitly passed as inputs. A build function
308 always produces the same result when passed a given set of inputs. It
309 cannot alter the environment of the running system in
310 any way; for instance, it cannot create, modify, or delete files outside
311 of its build and installation directories. This is achieved by running
312 build processes in isolated environments (or @dfn{containers}), where only their
313 explicit inputs are visible.
316 The result of package build functions is @dfn{cached} in the file
317 system, in a special directory called @dfn{the store} (@pxref{The
318 Store}). Each package is installed in a directory of its own in the
319 store---by default under @file{/gnu/store}. The directory name contains
320 a hash of all the inputs used to build that package; thus, changing an
321 input yields a different directory name.
323 This approach is the foundation for the salient features of Guix: support
324 for transactional package upgrade and rollback, per-user installation, and
325 garbage collection of packages (@pxref{Features}).
328 @c *********************************************************************
330 @chapter Installation
332 GNU Guix is available for download from its website at
333 @url{http://www.gnu.org/software/guix/}. This section describes the
334 software requirements of Guix, as well as how to install it and get
337 Note that this section is concerned with the installation of the package
338 manager, which can be done on top of a running GNU/Linux system. If,
339 instead, you want to install the complete GNU operating system,
340 @pxref{System Installation}.
342 @cindex foreign distro
343 When installed on a running GNU/Linux system---thereafter called a
344 @dfn{foreign distro}---GNU@tie{}Guix complements the available tools
345 without interference. Its data lives exclusively in two directories,
346 usually @file{/gnu/store} and @file{/var/guix}; other files on your
347 system, such as @file{/etc}, are left untouched.
350 * Binary Installation:: Getting Guix running in no time!
351 * Requirements:: Software needed to build and run Guix.
352 * Running the Test Suite:: Testing Guix.
353 * Setting Up the Daemon:: Preparing the build daemon's environment.
354 * Invoking guix-daemon:: Running the build daemon.
355 * Application Setup:: Application-specific setup.
358 @node Binary Installation
359 @section Binary Installation
361 This section describes how to install Guix on an arbitrary system from a
362 self-contained tarball providing binaries for Guix and for all its
363 dependencies. This is often quicker than installing from source, which
364 is described in the next sections. The only requirement is to have
367 Installing goes along these lines:
371 Download the binary tarball from
372 @indicateurl{ftp://alpha.gnu.org/gnu/guix/guix-binary-@value{VERSION}.@var{system}.tar.xz},
373 where @var{system} is @code{x86_64-linux} for an @code{x86_64} machine
374 already running the kernel Linux, and so on.
376 Make sure to download the associated @file{.sig} file and to verify the
377 authenticity of the tarball against it, along these lines:
380 $ wget ftp://alpha.gnu.org/gnu/guix/guix-binary-@value{VERSION}.@var{system}.tar.xz.sig
381 $ gpg --verify guix-binary-@value{VERSION}.@var{system}.tar.xz.sig
384 If that command fails because you do not have the required public key,
385 then run this command to import it:
388 $ gpg --keyserver pgp.mit.edu --recv-keys 090B11993D9AEBB5
392 and rerun the @code{gpg --verify} command.
399 # tar --warning=no-timestamp -xf \
400 guix-binary-@value{VERSION}.@var{system}.tar.xz
401 # mv var/guix /var/ && mv gnu /
404 This creates @file{/gnu/store} (@pxref{The Store}) and @file{/var/guix}.
405 The latter contains a ready-to-use profile for @code{root} (see next
408 Do @emph{not} unpack the tarball on a working Guix system since that
409 would overwrite its own essential files.
411 The @code{--warning=no-timestamp} option makes sure GNU@tie{}tar does
412 not emit warnings about ``implausibly old time stamps'' (such
413 warnings were triggered by GNU@tie{}tar 1.26 and older; recent
415 They stem from the fact that all the
416 files in the archive have their modification time set to zero (which
417 means January 1st, 1970.) This is done on purpose to make sure the
418 archive content is independent of its creation time, thus making it
422 Make @code{root}'s profile available under @file{~/.guix-profile}:
425 # ln -sf /var/guix/profiles/per-user/root/guix-profile \
430 Create the group and user accounts for build users as explained below
431 (@pxref{Build Environment Setup}).
434 Run the daemon, and set it to automatically start on boot.
436 If your host distro uses the systemd init system, this can be achieved
440 # cp ~root/.guix-profile/lib/systemd/system/guix-daemon.service \
442 # systemctl start guix-daemon && systemctl enable guix-daemon
445 If your host distro uses the Upstart init system:
448 # cp ~root/.guix-profile/lib/upstart/system/guix-daemon.conf /etc/init/
452 Otherwise, you can still start the daemon manually with:
455 # ~root/.guix-profile/bin/guix-daemon --build-users-group=guixbuild
459 Make the @command{guix} command available to other users on the machine,
463 # mkdir -p /usr/local/bin
465 # ln -s /var/guix/profiles/per-user/root/guix-profile/bin/guix
468 It is also a good idea to make the Info version of this manual available
472 # mkdir -p /usr/local/share/info
473 # cd /usr/local/share/info
474 # for i in /var/guix/profiles/per-user/root/guix-profile/share/info/* ;
478 That way, assuming @file{/usr/local/share/info} is in the search path,
479 running @command{info guix} will open this manual (@pxref{Other Info
480 Directories,,, texinfo, GNU Texinfo}, for more details on changing the
484 To use substitutes from @code{hydra.gnu.org} or one of its mirrors
485 (@pxref{Substitutes}), authorize them:
488 # guix archive --authorize < ~root/.guix-profile/share/guix/hydra.gnu.org.pub
492 This completes root-level install of Guix. Each user will need to
493 perform additional steps to make their Guix envionment ready for use,
494 @pxref{Application Setup}.
496 You can confirm that Guix is working by installing a sample package into
500 # guix package -i hello
503 The @code{guix} package must remain available in @code{root}'s profile,
504 or it would become subject to garbage collection---in which case you
505 would find yourself badly handicapped by the lack of the @command{guix}
506 command. In other words, do not remove @code{guix} by running
507 @code{guix package -r guix}.
509 The binary installation tarball can be (re)produced and verified simply
510 by running the following command in the Guix source tree:
513 make guix-binary.@var{system}.tar.xz
518 @section Requirements
520 This section lists requirements when building Guix from source. The
521 build procedure for Guix is the same as for other GNU software, and is
522 not covered here. Please see the files @file{README} and @file{INSTALL}
523 in the Guix source tree for additional details.
525 GNU Guix depends on the following packages:
528 @item @url{http://gnu.org/software/guile/, GNU Guile}, version 2.0.7 or later;
529 @item @url{http://gnupg.org/, GNU libgcrypt};
530 @item @url{http://www.gnu.org/software/make/, GNU Make}.
533 The following dependencies are optional:
537 Installing @uref{http://gnutls.org/, GnuTLS-Guile} will allow you to
538 access @code{https} URLs for substitutes, which is highly recommended
539 (@pxref{Substitutes}). It also allows you to access HTTPS URLs with the
540 @command{guix download} command (@pxref{Invoking guix download}), the
541 @command{guix import pypi} command, and the @command{guix import cpan}
542 command. @xref{Guile Preparations, how to install the GnuTLS bindings
543 for Guile,, gnutls-guile, GnuTLS-Guile}.
547 @url{http://savannah.nongnu.org/projects/guile-json/, Guile-JSON} will
548 allow you to use the @command{guix import pypi} command (@pxref{Invoking
549 guix import}). It is of
550 interest primarily for developers and not for casual users.
553 When @url{http://zlib.net, zlib} is available, @command{guix publish}
554 can compress build byproducts (@pxref{Invoking guix publish}).
557 Unless @code{--disable-daemon} was passed to @command{configure}, the
558 following packages are also needed:
561 @item @url{http://sqlite.org, SQLite 3};
562 @item @url{http://www.bzip.org, libbz2};
563 @item @url{http://gcc.gnu.org, GCC's g++}, with support for the
567 When configuring Guix on a system that already has a Guix installation,
568 be sure to specify the same state directory as the existing installation
569 using the @code{--localstatedir} option of the @command{configure}
570 script (@pxref{Directory Variables, @code{localstatedir},, standards,
571 GNU Coding Standards}). The @command{configure} script protects against
572 unintended misconfiguration of @var{localstatedir} so you do not
573 inadvertently corrupt your store (@pxref{The Store}).
575 When a working installation of @url{http://nixos.org/nix/, the Nix package
576 manager} is available, you
577 can instead configure Guix with @code{--disable-daemon}. In that case,
578 Nix replaces the three dependencies above.
580 Guix is compatible with Nix, so it is possible to share the same store
581 between both. To do so, you must pass @command{configure} not only the
582 same @code{--with-store-dir} value, but also the same
583 @code{--localstatedir} value. The latter is essential because it
584 specifies where the database that stores metadata about the store is
585 located, among other things. The default values for Nix are
586 @code{--with-store-dir=/nix/store} and @code{--localstatedir=/nix/var}.
587 Note that @code{--disable-daemon} is not required if
588 your goal is to share the store with Nix.
590 @node Running the Test Suite
591 @section Running the Test Suite
593 After a successful @command{configure} and @code{make} run, it is a good
594 idea to run the test suite. It can help catch issues with the setup or
595 environment, or bugs in Guix itself---and really, reporting test
596 failures is a good way to help improve the software. To run the test
603 Test cases can run in parallel: you can use the @code{-j} option of
604 GNU@tie{}make to speed things up. The first run may take a few minutes
605 on a recent machine; subsequent runs will be faster because the store
606 that is created for test purposes will already have various things in
609 It is also possible to run a subset of the tests by defining the
610 @code{TESTS} makefile variable as in this example:
613 make check TESTS="tests/store.scm tests/cpio.scm"
616 By default, tests results are displayed at a file level. In order to
617 see the details of every individual test cases, it is possible to define
618 the @code{SCM_LOG_DRIVER_FLAGS} makefile variable as in this example:
621 make check TESTS="tests/base64.scm" SCM_LOG_DRIVER_FLAGS="--brief=no"
624 Upon failure, please email @email{bug-guix@@gnu.org} and attach the
625 @file{test-suite.log} file. Please specify the Guix version being used
626 as well as version numbers of the dependencies (@pxref{Requirements}) in
629 Guix also comes with a whole-system test suite that tests complete
630 GuixSD operating system instances. It can only run on systems where
631 Guix is already installed, using:
638 or, again, by defining @code{TESTS} to select a subset of tests to run:
641 make check-system TESTS="basic mcron"
644 These system tests are defined in the @code{(gnu tests @dots{})}
645 modules. They work by running the operating systems under test with
646 lightweight instrumentation in a virtual machine (VM). They can be
647 computationally intensive or rather cheap, depending on whether
648 substitutes are available for their dependencies (@pxref{Substitutes}).
649 Some of them require a lot of storage space to hold VM images.
651 Again in case of test failures, please send @email{bug-guix@@gnu.org}
654 @node Setting Up the Daemon
655 @section Setting Up the Daemon
658 Operations such as building a package or running the garbage collector
659 are all performed by a specialized process, the @dfn{build daemon}, on
660 behalf of clients. Only the daemon may access the store and its
661 associated database. Thus, any operation that manipulates the store
662 goes through the daemon. For instance, command-line tools such as
663 @command{guix package} and @command{guix build} communicate with the
664 daemon (@i{via} remote procedure calls) to instruct it what to do.
666 The following sections explain how to prepare the build daemon's
667 environment. See also @ref{Substitutes}, for information on how to allow
668 the daemon to download pre-built binaries.
671 * Build Environment Setup:: Preparing the isolated build environment.
672 * Daemon Offload Setup:: Offloading builds to remote machines.
675 @node Build Environment Setup
676 @subsection Build Environment Setup
678 In a standard multi-user setup, Guix and its daemon---the
679 @command{guix-daemon} program---are installed by the system
680 administrator; @file{/gnu/store} is owned by @code{root} and
681 @command{guix-daemon} runs as @code{root}. Unprivileged users may use
682 Guix tools to build packages or otherwise access the store, and the
683 daemon will do it on their behalf, ensuring that the store is kept in a
684 consistent state, and allowing built packages to be shared among users.
687 When @command{guix-daemon} runs as @code{root}, you may not want package
688 build processes themselves to run as @code{root} too, for obvious
689 security reasons. To avoid that, a special pool of @dfn{build users}
690 should be created for use by build processes started by the daemon.
691 These build users need not have a shell and a home directory: they will
692 just be used when the daemon drops @code{root} privileges in build
693 processes. Having several such users allows the daemon to launch
694 distinct build processes under separate UIDs, which guarantees that they
695 do not interfere with each other---an essential feature since builds are
696 regarded as pure functions (@pxref{Introduction}).
698 On a GNU/Linux system, a build user pool may be created like this (using
699 Bash syntax and the @code{shadow} commands):
701 @c See http://lists.gnu.org/archive/html/bug-guix/2013-01/msg00239.html
702 @c for why `-G' is needed.
704 # groupadd --system guixbuild
705 # for i in `seq -w 1 10`;
707 useradd -g guixbuild -G guixbuild \
708 -d /var/empty -s `which nologin` \
709 -c "Guix build user $i" --system \
715 The number of build users determines how many build jobs may run in
716 parallel, as specified by the @option{--max-jobs} option
717 (@pxref{Invoking guix-daemon, @option{--max-jobs}}). To use
718 @command{guix system vm} and related commands, you may need to add the
719 build users to the @code{kvm} group so they can access @file{/dev/kvm},
720 using @code{-G guixbuild,kvm} instead of @code{-G guixbuild}
721 (@pxref{Invoking guix system}).
723 The @code{guix-daemon} program may then be run as @code{root} with the
724 following command@footnote{If your machine uses the systemd init system,
725 dropping the @file{@var{prefix}/lib/systemd/system/guix-daemon.service}
726 file in @file{/etc/systemd/system} will ensure that
727 @command{guix-daemon} is automatically started. Similarly, if your
728 machine uses the Upstart init system, drop the
729 @file{@var{prefix}/lib/upstart/system/guix-daemon.conf}
730 file in @file{/etc/init}.}:
733 # guix-daemon --build-users-group=guixbuild
738 This way, the daemon starts build processes in a chroot, under one of
739 the @code{guixbuilder} users. On GNU/Linux, by default, the chroot
740 environment contains nothing but:
742 @c Keep this list in sync with libstore/build.cc! -----------------------
745 a minimal @code{/dev} directory, created mostly independently from the
746 host @code{/dev}@footnote{``Mostly'', because while the set of files
747 that appear in the chroot's @code{/dev} is fixed, most of these files
748 can only be created if the host has them.};
751 the @code{/proc} directory; it only shows the processes of the container
752 since a separate PID name space is used;
755 @file{/etc/passwd} with an entry for the current user and an entry for
759 @file{/etc/group} with an entry for the user's group;
762 @file{/etc/hosts} with an entry that maps @code{localhost} to
766 a writable @file{/tmp} directory.
769 You can influence the directory where the daemon stores build trees
770 @i{via} the @code{TMPDIR} environment variable. However, the build tree
771 within the chroot is always called @file{/tmp/guix-build-@var{name}.drv-0},
772 where @var{name} is the derivation name---e.g., @code{coreutils-8.24}.
773 This way, the value of @code{TMPDIR} does not leak inside build
774 environments, which avoids discrepancies in cases where build processes
775 capture the name of their build tree.
778 The daemon also honors the @code{http_proxy} environment variable for
779 HTTP downloads it performs, be it for fixed-output derivations
780 (@pxref{Derivations}) or for substitutes (@pxref{Substitutes}).
782 If you are installing Guix as an unprivileged user, it is still possible
783 to run @command{guix-daemon} provided you pass @code{--disable-chroot}.
784 However, build processes will not be isolated from one another, and not
785 from the rest of the system. Thus, build processes may interfere with
786 each other, and may access programs, libraries, and other files
787 available on the system---making it much harder to view them as
788 @emph{pure} functions.
791 @node Daemon Offload Setup
792 @subsection Using the Offload Facility
796 When desired, the build daemon can @dfn{offload}
797 derivation builds to other machines
798 running Guix, using the @code{offload} @dfn{build hook}. When that
799 feature is enabled, a list of user-specified build machines is read from
800 @file{/etc/guix/machines.scm}; every time a build is requested, for
801 instance via @code{guix build}, the daemon attempts to offload it to one
802 of the machines that satisfy the constraints of the derivation, in
803 particular its system type---e.g., @file{x86_64-linux}. Missing
804 prerequisites for the build are copied over SSH to the target machine,
805 which then proceeds with the build; upon success the output(s) of the
806 build are copied back to the initial machine.
808 The @file{/etc/guix/machines.scm} file typically looks like this:
812 (name "eightysix.example.org")
813 (system "x86_64-linux")
815 (speed 2.)) ; incredibly fast!
818 (name "meeps.example.org")
819 (system "mips64el-linux")
822 (string-append (getenv "HOME")
823 "/.lsh/identity-for-guix"))))
827 In the example above we specify a list of two build machines, one for
828 the @code{x86_64} architecture and one for the @code{mips64el}
831 In fact, this file is---not surprisingly!---a Scheme file that is
832 evaluated when the @code{offload} hook is started. Its return value
833 must be a list of @code{build-machine} objects. While this example
834 shows a fixed list of build machines, one could imagine, say, using
835 DNS-SD to return a list of potential build machines discovered in the
836 local network (@pxref{Introduction, Guile-Avahi,, guile-avahi, Using
837 Avahi in Guile Scheme Programs}). The @code{build-machine} data type is
840 @deftp {Data Type} build-machine
841 This data type represents build machines to which the daemon may offload
842 builds. The important fields are:
847 The host name of the remote machine.
850 The system type of the remote machine---e.g., @code{"x86_64-linux"}.
853 The user account to use when connecting to the remote machine over SSH.
854 Note that the SSH key pair must @emph{not} be passphrase-protected, to
855 allow non-interactive logins.
859 A number of optional fields may be specified:
864 Port number of SSH server on the machine (default: 22).
867 The SSH private key file to use when connecting to the machine.
869 Currently offloading uses GNU@tie{}lsh as its SSH client
870 (@pxref{Invoking lsh,,, GNU lsh Manual}). Thus, the key file here must
871 be an lsh key file. This may change in the future, though.
873 @item parallel-builds
874 The number of builds that may run in parallel on the machine (1 by
878 A ``relative speed factor''. The offload scheduler will tend to prefer
879 machines with a higher speed factor.
882 A list of strings denoting specific features supported by the machine.
883 An example is @code{"kvm"} for machines that have the KVM Linux modules
884 and corresponding hardware support. Derivations can request features by
885 name, and they will be scheduled on matching build machines.
890 The @code{guix} command must be in the search path on the build
891 machines, since offloading works by invoking the @code{guix archive} and
892 @code{guix build} commands. In addition, the Guix modules must be in
893 @code{$GUILE_LOAD_PATH} on the build machine---you can check whether
894 this is the case by running:
897 lsh build-machine guile -c "'(use-modules (guix config))'"
900 There is one last thing to do once @file{machines.scm} is in place. As
901 explained above, when offloading, files are transferred back and forth
902 between the machine stores. For this to work, you first need to
903 generate a key pair on each machine to allow the daemon to export signed
904 archives of files from the store (@pxref{Invoking guix archive}):
907 # guix archive --generate-key
911 Each build machine must authorize the key of the master machine so that
912 it accepts store items it receives from the master:
915 # guix archive --authorize < master-public-key.txt
919 Likewise, the master machine must authorize the key of each build machine.
921 All the fuss with keys is here to express pairwise mutual trust
922 relations between the master and the build machines. Concretely, when
923 the master receives files from a build machine (and @i{vice versa}), its
924 build daemon can make sure they are genuine, have not been tampered
925 with, and that they are signed by an authorized key.
928 @node Invoking guix-daemon
929 @section Invoking @command{guix-daemon}
931 The @command{guix-daemon} program implements all the functionality to
932 access the store. This includes launching build processes, running the
933 garbage collector, querying the availability of a build result, etc. It
934 is normally run as @code{root} like this:
937 # guix-daemon --build-users-group=guixbuild
941 For details on how to set it up, @pxref{Setting Up the Daemon}.
944 @cindex container, build environment
945 @cindex build environment
946 @cindex reproducible builds
947 By default, @command{guix-daemon} launches build processes under
948 different UIDs, taken from the build group specified with
949 @code{--build-users-group}. In addition, each build process is run in a
950 chroot environment that only contains the subset of the store that the
951 build process depends on, as specified by its derivation
952 (@pxref{Programming Interface, derivation}), plus a set of specific
953 system directories. By default, the latter contains @file{/dev} and
954 @file{/dev/pts}. Furthermore, on GNU/Linux, the build environment is a
955 @dfn{container}: in addition to having its own file system tree, it has
956 a separate mount name space, its own PID name space, network name space,
957 etc. This helps achieve reproducible builds (@pxref{Features}).
959 When the daemon performs a build on behalf of the user, it creates a
960 build directory under @file{/tmp} or under the directory specified by
961 its @code{TMPDIR} environment variable; this directory is shared with
962 the container for the duration of the build. Be aware that using a
963 directory other than @file{/tmp} can affect build results---for example,
964 with a longer directory name, a build process that uses Unix-domain
965 sockets might hit the name length limitation for @code{sun_path}, which
966 it would otherwise not hit.
968 The build directory is automatically deleted upon completion, unless the
969 build failed and the client specified @option{--keep-failed}
970 (@pxref{Invoking guix build, @option{--keep-failed}}).
972 The following command-line options are supported:
975 @item --build-users-group=@var{group}
976 Take users from @var{group} to run build processes (@pxref{Setting Up
977 the Daemon, build users}).
979 @item --no-substitutes
981 Do not use substitutes for build products. That is, always build things
982 locally instead of allowing downloads of pre-built binaries
983 (@pxref{Substitutes}).
985 By default substitutes are used, unless the client---such as the
986 @command{guix package} command---is explicitly invoked with
987 @code{--no-substitutes}.
989 When the daemon runs with @code{--no-substitutes}, clients can still
990 explicitly enable substitution @i{via} the @code{set-build-options}
991 remote procedure call (@pxref{The Store}).
993 @item --substitute-urls=@var{urls}
994 @anchor{daemon-substitute-urls}
995 Consider @var{urls} the default whitespace-separated list of substitute
996 source URLs. When this option is omitted,
997 @indicateurl{https://mirror.hydra.gnu.org https://hydra.gnu.org} is used
998 (@code{mirror.hydra.gnu.org} is a mirror of @code{hydra.gnu.org}).
1000 This means that substitutes may be downloaded from @var{urls}, as long
1001 as they are signed by a trusted signature (@pxref{Substitutes}).
1004 @item --no-build-hook
1005 Do not use the @dfn{build hook}.
1007 The build hook is a helper program that the daemon can start and to
1008 which it submits build requests. This mechanism is used to offload
1009 builds to other machines (@pxref{Daemon Offload Setup}).
1011 @item --cache-failures
1012 Cache build failures. By default, only successful builds are cached.
1014 When this option is used, @command{guix gc --list-failures} can be used
1015 to query the set of store items marked as failed; @command{guix gc
1016 --clear-failures} removes store items from the set of cached failures.
1017 @xref{Invoking guix gc}.
1019 @item --cores=@var{n}
1021 Use @var{n} CPU cores to build each derivation; @code{0} means as many
1024 The default value is @code{0}, but it may be overridden by clients, such
1025 as the @code{--cores} option of @command{guix build} (@pxref{Invoking
1028 The effect is to define the @code{NIX_BUILD_CORES} environment variable
1029 in the build process, which can then use it to exploit internal
1030 parallelism---for instance, by running @code{make -j$NIX_BUILD_CORES}.
1032 @item --max-jobs=@var{n}
1034 Allow at most @var{n} build jobs in parallel. The default value is
1035 @code{1}. Setting it to @code{0} means that no builds will be performed
1036 locally; instead, the daemon will offload builds (@pxref{Daemon Offload
1037 Setup}), or simply fail.
1039 @item --rounds=@var{N}
1040 Build each derivation @var{n} times in a row, and raise an error if
1041 consecutive build results are not bit-for-bit identical. Note that this
1042 setting can be overridden by clients such as @command{guix build}
1043 (@pxref{Invoking guix build}).
1045 When used in conjunction with @option{--keep-failed}, the differing
1046 output is kept in the store, under @file{/gnu/store/@dots{}-check}.
1047 This makes it easy to look for differences between the two results.
1050 Produce debugging output.
1052 This is useful to debug daemon start-up issues, but then it may be
1053 overridden by clients, for example the @code{--verbosity} option of
1054 @command{guix build} (@pxref{Invoking guix build}).
1056 @item --chroot-directory=@var{dir}
1057 Add @var{dir} to the build chroot.
1059 Doing this may change the result of build processes---for instance if
1060 they use optional dependencies found in @var{dir} when it is available,
1061 and not otherwise. For that reason, it is not recommended to do so.
1062 Instead, make sure that each derivation declares all the inputs that it
1065 @item --disable-chroot
1066 Disable chroot builds.
1068 Using this option is not recommended since, again, it would allow build
1069 processes to gain access to undeclared dependencies. It is necessary,
1070 though, when @command{guix-daemon} is running under an unprivileged user
1073 @item --disable-log-compression
1074 Disable compression of the build logs.
1076 Unless @code{--lose-logs} is used, all the build logs are kept in the
1077 @var{localstatedir}. To save space, the daemon automatically compresses
1078 them with bzip2 by default. This option disables that.
1080 @item --disable-deduplication
1081 @cindex deduplication
1082 Disable automatic file ``deduplication'' in the store.
1084 By default, files added to the store are automatically ``deduplicated'':
1085 if a newly added file is identical to another one found in the store,
1086 the daemon makes the new file a hard link to the other file. This can
1087 noticeably reduce disk usage, at the expense of slightly increased
1088 input/output load at the end of a build process. This option disables
1091 @item --gc-keep-outputs[=yes|no]
1092 Tell whether the garbage collector (GC) must keep outputs of live
1095 When set to ``yes'', the GC will keep the outputs of any live derivation
1096 available in the store---the @code{.drv} files. The default is ``no'',
1097 meaning that derivation outputs are kept only if they are GC roots.
1099 @item --gc-keep-derivations[=yes|no]
1100 Tell whether the garbage collector (GC) must keep derivations
1101 corresponding to live outputs.
1103 When set to ``yes'', as is the case by default, the GC keeps
1104 derivations---i.e., @code{.drv} files---as long as at least one of their
1105 outputs is live. This allows users to keep track of the origins of
1106 items in their store. Setting it to ``no'' saves a bit of disk space.
1108 Note that when both @code{--gc-keep-derivations} and
1109 @code{--gc-keep-outputs} are used, the effect is to keep all the build
1110 prerequisites (the sources, compiler, libraries, and other build-time
1111 tools) of live objects in the store, regardless of whether these
1112 prerequisites are live. This is convenient for developers since it
1113 saves rebuilds or downloads.
1115 @item --impersonate-linux-2.6
1116 On Linux-based systems, impersonate Linux 2.6. This means that the
1117 kernel's @code{uname} system call will report 2.6 as the release number.
1119 This might be helpful to build programs that (usually wrongfully) depend
1120 on the kernel version number.
1123 Do not keep build logs. By default they are kept under
1124 @code{@var{localstatedir}/guix/log}.
1126 @item --system=@var{system}
1127 Assume @var{system} as the current system type. By default it is the
1128 architecture/kernel pair found at configure time, such as
1129 @code{x86_64-linux}.
1131 @item --listen=@var{socket}
1132 Listen for connections on @var{socket}, the file name of a Unix-domain
1133 socket. The default socket is
1134 @file{@var{localstatedir}/daemon-socket/socket}. This option is only
1135 useful in exceptional circumstances, such as if you need to run several
1136 daemons on the same machine.
1140 @node Application Setup
1141 @section Application Setup
1143 @cindex foreign distro
1144 When using Guix on top of GNU/Linux distribution other than GuixSD---a
1145 so-called @dfn{foreign distro}---a few additional steps are needed to
1146 get everything in place. Here are some of them.
1150 @anchor{locales-and-locpath}
1151 @cindex locales, when not on GuixSD
1153 @vindex GUIX_LOCPATH
1154 Packages installed @i{via} Guix will not use the locale data of the
1155 host system. Instead, you must first install one of the locale packages
1156 available with Guix and then define the @code{GUIX_LOCPATH} environment
1160 $ guix package -i glibc-locales
1161 $ export GUIX_LOCPATH=$HOME/.guix-profile/lib/locale
1164 Note that the @code{glibc-locales} package contains data for all the
1165 locales supported by the GNU@tie{}libc and weighs in at around
1166 110@tie{}MiB. Alternatively, the @code{glibc-utf8-locales} is smaller but
1167 limited to a few UTF-8 locales.
1169 The @code{GUIX_LOCPATH} variable plays a role similar to @code{LOCPATH}
1170 (@pxref{Locale Names, @code{LOCPATH},, libc, The GNU C Library Reference
1171 Manual}). There are two important differences though:
1175 @code{GUIX_LOCPATH} is honored only by the libc in Guix, and not by the libc
1176 provided by foreign distros. Thus, using @code{GUIX_LOCPATH} allows you
1177 to make sure the programs of the foreign distro will not end up loading
1178 incompatible locale data.
1181 libc suffixes each entry of @code{GUIX_LOCPATH} with @code{/X.Y}, where
1182 @code{X.Y} is the libc version---e.g., @code{2.22}. This means that,
1183 should your Guix profile contain a mixture of programs linked against
1184 different libc version, each libc version will only try to load locale
1185 data in the right format.
1188 This is important because the locale data format used by different libc
1189 versions may be incompatible.
1191 @subsection X11 Fonts
1193 The majority of graphical applications use Fontconfig to locate and
1194 load fonts and perform X11-client-side rendering. The @code{fontconfig}
1195 package in Guix looks for fonts in @file{$HOME/.guix-profile}
1196 by default. Thus, to allow graphical applications installed with Guix
1197 to display fonts, you have to install fonts with Guix as well.
1198 Essential font packages include @code{gs-fonts}, @code{font-dejavu}, and
1199 @code{font-gnu-freefont-ttf}.
1201 To display text written in Chinese languages, Japanese, or Korean in
1202 graphical applications, consider installing
1203 @code{font-adobe-source-han-sans} or @code{font-wqy-zenhei}. The former
1204 has multiple outputs, one per language family (@pxref{Packages with
1205 Multiple Outputs}). For instance, the following command installs fonts
1206 for Chinese languages:
1209 guix package -i font-adobe-source-han-sans:cn
1212 Older programs such as @command{xterm} do not use Fontconfig and instead
1213 rely on server-side font rendering. Such programs require to specify a
1214 full name of a font using XLFD (X Logical Font Description), like this:
1217 -*-dejavu sans-medium-r-normal-*-*-100-*-*-*-*-*-1
1220 To be able to use such full names for the TrueType fonts installed in
1221 your Guix profile, you need to extend the font path of the X server:
1224 xset +fp ~/.guix-profile/share/fonts/truetype
1227 After that, you can run @code{xlsfonts} (from @code{xlsfonts} package)
1228 to make sure your TrueType fonts are listed there.
1230 @subsection X.509 Certificates
1232 The @code{nss-certs} package provides X.509 certificates, which allow
1233 programs to authenticate Web servers accessed over HTTPS.
1235 When using Guix on a foreign distro, you can install this package and
1236 define the relevant environment variables so that packages know where to
1237 look for certificates. @pxref{X.509 Certificates}, for detailed
1240 @subsection Emacs Packages
1242 When you install Emacs packages with Guix, the elisp files may be placed
1243 either in @file{$HOME/.guix-profile/share/emacs/site-lisp/} or in
1245 @file{$HOME/.guix-profile/share/emacs/site-lisp/guix.d/}. The latter
1246 directory exists because potentially there may exist thousands of Emacs
1247 packages and storing all their files in a single directory may be not
1248 reliable (because of name conflicts). So we think using a separate
1249 directory for each package is a good idea. It is very similar to how
1250 the Emacs package system organizes the file structure (@pxref{Package
1251 Files,,, emacs, The GNU Emacs Manual}).
1253 By default, Emacs (installed with Guix) ``knows'' where these packages
1254 are placed, so you do not need to perform any configuration. If, for
1255 some reason, you want to avoid auto-loading Emacs packages installed
1256 with Guix, you can do so by running Emacs with @code{--no-site-file}
1257 option (@pxref{Init File,,, emacs, The GNU Emacs Manual}).
1261 @c *********************************************************************
1262 @node Package Management
1263 @chapter Package Management
1265 The purpose of GNU Guix is to allow users to easily install, upgrade, and
1266 remove software packages, without having to know about their build
1267 procedures or dependencies. Guix also goes beyond this obvious set of
1270 This chapter describes the main features of Guix, as well as the package
1271 management tools it provides. Two user interfaces are provided for
1272 routine package management tasks: A command-line interface described below
1273 (@pxref{Invoking guix package, @code{guix package}}), as well as a visual user
1274 interface in Emacs described in a subsequent chapter (@pxref{Emacs Interface}).
1277 * Features:: How Guix will make your life brighter.
1278 * Invoking guix package:: Package installation, removal, etc.
1279 * Substitutes:: Downloading pre-built binaries.
1280 * Packages with Multiple Outputs:: Single source package, multiple outputs.
1281 * Invoking guix gc:: Running the garbage collector.
1282 * Invoking guix pull:: Fetching the latest Guix and distribution.
1283 * Invoking guix archive:: Exporting and importing store files.
1289 When using Guix, each package ends up in the @dfn{package store}, in its
1290 own directory---something that resembles
1291 @file{/gnu/store/xxx-package-1.2}, where @code{xxx} is a base32 string
1292 (note that Guix comes with an Emacs extension to shorten those file
1293 names, @pxref{Emacs Prettify}.)
1295 Instead of referring to these directories, users have their own
1296 @dfn{profile}, which points to the packages that they actually want to
1297 use. These profiles are stored within each user's home directory, at
1298 @code{$HOME/.guix-profile}.
1300 For example, @code{alice} installs GCC 4.7.2. As a result,
1301 @file{/home/alice/.guix-profile/bin/gcc} points to
1302 @file{/gnu/store/@dots{}-gcc-4.7.2/bin/gcc}. Now, on the same machine,
1303 @code{bob} had already installed GCC 4.8.0. The profile of @code{bob}
1304 simply continues to point to
1305 @file{/gnu/store/@dots{}-gcc-4.8.0/bin/gcc}---i.e., both versions of GCC
1306 coexist on the same system without any interference.
1308 The @command{guix package} command is the central tool to manage
1309 packages (@pxref{Invoking guix package}). It operates on the per-user
1310 profiles, and can be used @emph{with normal user privileges}.
1312 The command provides the obvious install, remove, and upgrade
1313 operations. Each invocation is actually a @emph{transaction}: either
1314 the specified operation succeeds, or nothing happens. Thus, if the
1315 @command{guix package} process is terminated during the transaction,
1316 or if a power outage occurs during the transaction, then the user's
1317 profile remains in its previous state, and remains usable.
1319 In addition, any package transaction may be @emph{rolled back}. So, if,
1320 for example, an upgrade installs a new version of a package that turns
1321 out to have a serious bug, users may roll back to the previous instance
1322 of their profile, which was known to work well. Similarly, the global
1323 system configuration on GuixSD is subject to
1324 transactional upgrades and roll-back
1325 (@pxref{Using the Configuration System}).
1327 All packages in the package store may be @emph{garbage-collected}.
1328 Guix can determine which packages are still referenced by user
1329 profiles, and remove those that are provably no longer referenced
1330 (@pxref{Invoking guix gc}). Users may also explicitly remove old
1331 generations of their profile so that the packages they refer to can be
1334 @cindex reproducibility
1335 @cindex reproducible builds
1336 Finally, Guix takes a @dfn{purely functional} approach to package
1337 management, as described in the introduction (@pxref{Introduction}).
1338 Each @file{/gnu/store} package directory name contains a hash of all the
1339 inputs that were used to build that package---compiler, libraries, build
1340 scripts, etc. This direct correspondence allows users to make sure a
1341 given package installation matches the current state of their
1342 distribution. It also helps maximize @dfn{build reproducibility}:
1343 thanks to the isolated build environments that are used, a given build
1344 is likely to yield bit-identical files when performed on different
1345 machines (@pxref{Invoking guix-daemon, container}).
1348 This foundation allows Guix to support @dfn{transparent binary/source
1349 deployment}. When a pre-built binary for a @file{/gnu/store} item is
1350 available from an external source---a @dfn{substitute}, Guix just
1351 downloads it and unpacks it;
1352 otherwise, it builds the package from source, locally
1353 (@pxref{Substitutes}). Because build results are usually bit-for-bit
1354 reproducible, users do not have to trust servers that provide
1355 substitutes: they can force a local build and @emph{challenge} providers
1356 (@pxref{Invoking guix challenge}).
1358 Control over the build environment is a feature that is also useful for
1359 developers. The @command{guix environment} command allows developers of
1360 a package to quickly set up the right development environment for their
1361 package, without having to manually install the dependencies of the
1362 package into their profile (@pxref{Invoking guix environment}).
1364 @node Invoking guix package
1365 @section Invoking @command{guix package}
1367 The @command{guix package} command is the tool that allows users to
1368 install, upgrade, and remove packages, as well as rolling back to
1369 previous configurations. It operates only on the user's own profile,
1370 and works with normal user privileges (@pxref{Features}). Its syntax
1374 guix package @var{options}
1377 Primarily, @var{options} specifies the operations to be performed during
1378 the transaction. Upon completion, a new profile is created, but
1379 previous @dfn{generations} of the profile remain available, should the user
1382 For example, to remove @code{lua} and install @code{guile} and
1383 @code{guile-cairo} in a single transaction:
1386 guix package -r lua -i guile guile-cairo
1389 @command{guix package} also supports a @dfn{declarative approach}
1390 whereby the user specifies the exact set of packages to be available and
1391 passes it @i{via} the @option{--manifest} option
1392 (@pxref{profile-manifest, @option{--manifest}}).
1394 For each user, a symlink to the user's default profile is automatically
1395 created in @file{$HOME/.guix-profile}. This symlink always points to the
1396 current generation of the user's default profile. Thus, users can add
1397 @file{$HOME/.guix-profile/bin} to their @code{PATH} environment
1398 variable, and so on.
1399 @cindex search paths
1400 If you are not using the Guix System Distribution, consider adding the
1401 following lines to your @file{~/.bash_profile} (@pxref{Bash Startup
1402 Files,,, bash, The GNU Bash Reference Manual}) so that newly-spawned
1403 shells get all the right environment variable definitions:
1406 GUIX_PROFILE="$HOME/.guix-profile" \
1407 source "$HOME/.guix-profile/etc/profile"
1410 In a multi-user setup, user profiles are stored in a place registered as
1411 a @dfn{garbage-collector root}, which @file{$HOME/.guix-profile} points
1412 to (@pxref{Invoking guix gc}). That directory is normally
1413 @code{@var{localstatedir}/profiles/per-user/@var{user}}, where
1414 @var{localstatedir} is the value passed to @code{configure} as
1415 @code{--localstatedir}, and @var{user} is the user name. The
1416 @file{per-user} directory is created when @command{guix-daemon} is
1417 started, and the @var{user} sub-directory is created by @command{guix
1420 The @var{options} can be among the following:
1424 @item --install=@var{package} @dots{}
1425 @itemx -i @var{package} @dots{}
1426 Install the specified @var{package}s.
1428 Each @var{package} may specify either a simple package name, such as
1429 @code{guile}, or a package name followed by an at-sign and version number,
1430 such as @code{guile@@1.8.8} or simply @code{guile@@1.8} (in the latter
1431 case, the newest version prefixed by @code{1.8} is selected.)
1433 If no version number is specified, the
1434 newest available version will be selected. In addition, @var{package}
1435 may contain a colon, followed by the name of one of the outputs of the
1436 package, as in @code{gcc:doc} or @code{binutils@@2.22:lib}
1437 (@pxref{Packages with Multiple Outputs}). Packages with a corresponding
1438 name (and optionally version) are searched for among the GNU
1439 distribution modules (@pxref{Package Modules}).
1441 @cindex propagated inputs
1442 Sometimes packages have @dfn{propagated inputs}: these are dependencies
1443 that automatically get installed along with the required package
1444 (@pxref{package-propagated-inputs, @code{propagated-inputs} in
1445 @code{package} objects}, for information about propagated inputs in
1446 package definitions).
1448 @anchor{package-cmd-propagated-inputs}
1449 An example is the GNU MPC library: its C header files refer to those of
1450 the GNU MPFR library, which in turn refer to those of the GMP library.
1451 Thus, when installing MPC, the MPFR and GMP libraries also get installed
1452 in the profile; removing MPC also removes MPFR and GMP---unless they had
1453 also been explicitly installed by the user.
1455 Besides, packages sometimes rely on the definition of environment
1456 variables for their search paths (see explanation of
1457 @code{--search-paths} below). Any missing or possibly incorrect
1458 environment variable definitions are reported here.
1460 @item --install-from-expression=@var{exp}
1462 Install the package @var{exp} evaluates to.
1464 @var{exp} must be a Scheme expression that evaluates to a
1465 @code{<package>} object. This option is notably useful to disambiguate
1466 between same-named variants of a package, with expressions such as
1467 @code{(@@ (gnu packages base) guile-final)}.
1469 Note that this option installs the first output of the specified
1470 package, which may be insufficient when needing a specific output of a
1471 multiple-output package.
1473 @item --install-from-file=@var{file}
1474 @itemx -f @var{file}
1475 Install the package that the code within @var{file} evaluates to.
1477 As an example, @var{file} might contain a definition like this
1478 (@pxref{Defining Packages}):
1481 @verbatiminclude package-hello.scm
1484 Developers may find it useful to include such a @file{guix.scm} file
1485 in the root of their project source tree that can be used to test
1486 development snapshots and create reproducible development environments
1487 (@pxref{Invoking guix environment}).
1489 @item --remove=@var{package} @dots{}
1490 @itemx -r @var{package} @dots{}
1491 Remove the specified @var{package}s.
1493 As for @code{--install}, each @var{package} may specify a version number
1494 and/or output name in addition to the package name. For instance,
1495 @code{-r glibc:debug} would remove the @code{debug} output of
1498 @item --upgrade[=@var{regexp} @dots{}]
1499 @itemx -u [@var{regexp} @dots{}]
1500 Upgrade all the installed packages. If one or more @var{regexp}s are
1501 specified, upgrade only installed packages whose name matches a
1502 @var{regexp}. Also see the @code{--do-not-upgrade} option below.
1504 Note that this upgrades package to the latest version of packages found
1505 in the distribution currently installed. To update your distribution,
1506 you should regularly run @command{guix pull} (@pxref{Invoking guix
1509 @item --do-not-upgrade[=@var{regexp} @dots{}]
1510 When used together with the @code{--upgrade} option, do @emph{not}
1511 upgrade any packages whose name matches a @var{regexp}. For example, to
1512 upgrade all packages in the current profile except those containing the
1513 substring ``emacs'':
1516 $ guix package --upgrade . --do-not-upgrade emacs
1519 @item @anchor{profile-manifest}--manifest=@var{file}
1520 @itemx -m @var{file}
1521 @cindex profile declaration
1522 @cindex profile manifest
1523 Create a new generation of the profile from the manifest object
1524 returned by the Scheme code in @var{file}.
1526 This allows you to @emph{declare} the profile's contents rather than
1527 constructing it through a sequence of @code{--install} and similar
1528 commands. The advantage is that @var{file} can be put under version
1529 control, copied to different machines to reproduce the same profile, and
1532 @c FIXME: Add reference to (guix profile) documentation when available.
1533 @var{file} must return a @dfn{manifest} object, which is roughly a list
1536 @findex packages->manifest
1538 (use-package-modules guile emacs)
1543 ;; Use a specific package output.
1544 (list guile-2.0 "debug")))
1548 Roll back to the previous @dfn{generation} of the profile---i.e., undo
1549 the last transaction.
1551 When combined with options such as @code{--install}, roll back occurs
1552 before any other actions.
1554 When rolling back from the first generation that actually contains
1555 installed packages, the profile is made to point to the @dfn{zeroth
1556 generation}, which contains no files apart from its own metadata.
1558 After having rolled back, installing, removing, or upgrading packages
1559 overwrites previous future generations. Thus, the history of the
1560 generations in a profile is always linear.
1562 @item --switch-generation=@var{pattern}
1563 @itemx -S @var{pattern}
1564 Switch to a particular generation defined by @var{pattern}.
1566 @var{pattern} may be either a generation number or a number prefixed
1567 with ``+'' or ``-''. The latter means: move forward/backward by a
1568 specified number of generations. For example, if you want to return to
1569 the latest generation after @code{--roll-back}, use
1570 @code{--switch-generation=+1}.
1572 The difference between @code{--roll-back} and
1573 @code{--switch-generation=-1} is that @code{--switch-generation} will
1574 not make a zeroth generation, so if a specified generation does not
1575 exist, the current generation will not be changed.
1577 @item --search-paths[=@var{kind}]
1578 @cindex search paths
1579 Report environment variable definitions, in Bash syntax, that may be
1580 needed in order to use the set of installed packages. These environment
1581 variables are used to specify @dfn{search paths} for files used by some
1582 of the installed packages.
1584 For example, GCC needs the @code{CPATH} and @code{LIBRARY_PATH}
1585 environment variables to be defined so it can look for headers and
1586 libraries in the user's profile (@pxref{Environment Variables,,, gcc,
1587 Using the GNU Compiler Collection (GCC)}). If GCC and, say, the C
1588 library are installed in the profile, then @code{--search-paths} will
1589 suggest setting these variables to @code{@var{profile}/include} and
1590 @code{@var{profile}/lib}, respectively.
1592 The typical use case is to define these environment variables in the
1596 $ eval `guix package --search-paths`
1599 @var{kind} may be one of @code{exact}, @code{prefix}, or @code{suffix},
1600 meaning that the returned environment variable definitions will either
1601 be exact settings, or prefixes or suffixes of the current value of these
1602 variables. When omitted, @var{kind} defaults to @code{exact}.
1604 This option can also be used to compute the @emph{combined} search paths
1605 of several profiles. Consider this example:
1608 $ guix package -p foo -i guile
1609 $ guix package -p bar -i guile-json
1610 $ guix package -p foo -p bar --search-paths
1613 The last command above reports about the @code{GUILE_LOAD_PATH}
1614 variable, even though, taken individually, neither @file{foo} nor
1615 @file{bar} would lead to that recommendation.
1618 @item --profile=@var{profile}
1619 @itemx -p @var{profile}
1620 Use @var{profile} instead of the user's default profile.
1623 Produce verbose output. In particular, emit the build log of the
1624 environment on the standard error port.
1627 Use the bootstrap Guile to build the profile. This option is only
1628 useful to distribution developers.
1632 In addition to these actions, @command{guix package} supports the
1633 following options to query the current state of a profile, or the
1634 availability of packages:
1638 @item --search=@var{regexp}
1639 @itemx -s @var{regexp}
1640 @cindex searching for packages
1641 List the available packages whose name, synopsis, or description matches
1642 @var{regexp}. Print all the metadata of matching packages in
1643 @code{recutils} format (@pxref{Top, GNU recutils databases,, recutils,
1644 GNU recutils manual}).
1646 This allows specific fields to be extracted using the @command{recsel}
1647 command, for instance:
1650 $ guix package -s malloc | recsel -p name,version
1658 Similarly, to show the name of all the packages available under the
1659 terms of the GNU@tie{}LGPL version 3:
1662 $ guix package -s "" | recsel -p name -e 'license ~ "LGPL 3"'
1669 It is also possible to refine search results using several @code{-s}
1670 flags. For example, the following command returns a list of board
1674 $ guix package -s '\<board\>' -s game | recsel -p name
1679 If we were to omit @code{-s game}, we would also get software packages
1680 that deal with printed circuit boards; removing the angle brackets
1681 around @code{board} would further add packages that have to do with
1684 And now for a more elaborate example. The following command searches
1685 for cryptographic libraries, filters out Haskell, Perl, Python, and Ruby
1686 libraries, and prints the name and synopsis of the matching packages:
1689 $ guix package -s crypto -s library | \
1690 recsel -e '! (name ~ "^(ghc|perl|python|ruby)")' -p name,synopsis
1694 @xref{Selection Expressions,,, recutils, GNU recutils manual}, for more
1695 information on @dfn{selection expressions} for @code{recsel -e}.
1697 @item --show=@var{package}
1698 Show details about @var{package}, taken from the list of available packages, in
1699 @code{recutils} format (@pxref{Top, GNU recutils databases,, recutils, GNU
1703 $ guix package --show=python | recsel -p name,version
1711 You may also specify the full name of a package to only get details about a
1712 specific version of it:
1714 $ guix package --show=python-3.3.5 | recsel -p name,version
1721 @item --list-installed[=@var{regexp}]
1722 @itemx -I [@var{regexp}]
1723 List the currently installed packages in the specified profile, with the
1724 most recently installed packages shown last. When @var{regexp} is
1725 specified, list only installed packages whose name matches @var{regexp}.
1727 For each installed package, print the following items, separated by
1728 tabs: the package name, its version string, the part of the package that
1729 is installed (for instance, @code{out} for the default output,
1730 @code{include} for its headers, etc.), and the path of this package in
1733 @item --list-available[=@var{regexp}]
1734 @itemx -A [@var{regexp}]
1735 List packages currently available in the distribution for this system
1736 (@pxref{GNU Distribution}). When @var{regexp} is specified, list only
1737 installed packages whose name matches @var{regexp}.
1739 For each package, print the following items separated by tabs: its name,
1740 its version string, the parts of the package (@pxref{Packages with
1741 Multiple Outputs}), and the source location of its definition.
1743 @item --list-generations[=@var{pattern}]
1744 @itemx -l [@var{pattern}]
1745 Return a list of generations along with their creation dates; for each
1746 generation, show the installed packages, with the most recently
1747 installed packages shown last. Note that the zeroth generation is never
1750 For each installed package, print the following items, separated by
1751 tabs: the name of a package, its version string, the part of the package
1752 that is installed (@pxref{Packages with Multiple Outputs}), and the
1753 location of this package in the store.
1755 When @var{pattern} is used, the command returns only matching
1756 generations. Valid patterns include:
1759 @item @emph{Integers and comma-separated integers}. Both patterns denote
1760 generation numbers. For instance, @code{--list-generations=1} returns
1763 And @code{--list-generations=1,8,2} outputs three generations in the
1764 specified order. Neither spaces nor trailing commas are allowed.
1766 @item @emph{Ranges}. @code{--list-generations=2..9} prints the
1767 specified generations and everything in between. Note that the start of
1768 a range must be smaller than its end.
1770 It is also possible to omit the endpoint. For example,
1771 @code{--list-generations=2..}, returns all generations starting from the
1774 @item @emph{Durations}. You can also get the last @emph{N}@tie{}days, weeks,
1775 or months by passing an integer along with the first letter of the
1776 duration. For example, @code{--list-generations=20d} lists generations
1777 that are up to 20 days old.
1780 @item --delete-generations[=@var{pattern}]
1781 @itemx -d [@var{pattern}]
1782 When @var{pattern} is omitted, delete all generations except the current
1785 This command accepts the same patterns as @option{--list-generations}.
1786 When @var{pattern} is specified, delete the matching generations. When
1787 @var{pattern} specifies a duration, generations @emph{older} than the
1788 specified duration match. For instance, @code{--delete-generations=1m}
1789 deletes generations that are more than one month old.
1791 If the current generation matches, it is @emph{not} deleted. Also, the
1792 zeroth generation is never deleted.
1794 Note that deleting generations prevents rolling back to them.
1795 Consequently, this command must be used with care.
1799 Finally, since @command{guix package} may actually start build
1800 processes, it supports all the common build options (@pxref{Common Build
1801 Options}). It also supports package transformation options, such as
1802 @option{--with-source} (@pxref{Package Transformation Options}).
1803 However, note that package transformations are lost when upgrading; to
1804 preserve transformations across upgrades, you should define your own
1805 package variant in a Guile module and add it to @code{GUIX_PACKAGE_PATH}
1806 (@pxref{Defining Packages}).
1810 @section Substitutes
1813 @cindex pre-built binaries
1814 Guix supports transparent source/binary deployment, which means that it
1815 can either build things locally, or download pre-built items from a
1816 server. We call these pre-built items @dfn{substitutes}---they are
1817 substitutes for local build results. In many cases, downloading a
1818 substitute is much faster than building things locally.
1820 Substitutes can be anything resulting from a derivation build
1821 (@pxref{Derivations}). Of course, in the common case, they are
1822 pre-built package binaries, but source tarballs, for instance, which
1823 also result from derivation builds, can be available as substitutes.
1825 The @code{hydra.gnu.org} server is a front-end to a build farm that
1826 builds packages from the GNU distribution continuously for some
1827 architectures, and makes them available as substitutes (@pxref{Emacs
1828 Hydra}, for information on how to query the continuous integration
1829 server). This is the
1830 default source of substitutes; it can be overridden by passing the
1831 @option{--substitute-urls} option either to @command{guix-daemon}
1832 (@pxref{daemon-substitute-urls,, @code{guix-daemon --substitute-urls}})
1833 or to client tools such as @command{guix package}
1834 (@pxref{client-substitute-urls,, client @option{--substitute-urls}
1837 Substitute URLs can be either HTTP or HTTPS@footnote{For HTTPS access,
1838 the Guile bindings of GnuTLS must be installed. @xref{Requirements}.}
1839 HTTPS is recommended because communications are encrypted; conversely,
1840 using HTTP makes all communications visible to an eavesdropper, who
1841 could use the information gathered to determine, for instance, whether
1842 your system has unpatched security vulnerabilities.
1845 @cindex digital signatures
1846 To allow Guix to download substitutes from @code{hydra.gnu.org} or a
1848 must add its public key to the access control list (ACL) of archive
1849 imports, using the @command{guix archive} command (@pxref{Invoking guix
1850 archive}). Doing so implies that you trust @code{hydra.gnu.org} to not
1851 be compromised and to serve genuine substitutes.
1853 This public key is installed along with Guix, in
1854 @code{@var{prefix}/share/guix/hydra.gnu.org.pub}, where @var{prefix} is
1855 the installation prefix of Guix. If you installed Guix from source,
1856 make sure you checked the GPG signature of
1857 @file{guix-@value{VERSION}.tar.gz}, which contains this public key file.
1858 Then, you can run something like this:
1861 # guix archive --authorize < hydra.gnu.org.pub
1864 Once this is in place, the output of a command like @code{guix build}
1865 should change from something like:
1868 $ guix build emacs --dry-run
1869 The following derivations would be built:
1870 /gnu/store/yr7bnx8xwcayd6j95r2clmkdl1qh688w-emacs-24.3.drv
1871 /gnu/store/x8qsh1hlhgjx6cwsjyvybnfv2i37z23w-dbus-1.6.4.tar.gz.drv
1872 /gnu/store/1ixwp12fl950d15h2cj11c73733jay0z-alsa-lib-1.0.27.1.tar.bz2.drv
1873 /gnu/store/nlma1pw0p603fpfiqy7kn4zm105r5dmw-util-linux-2.21.drv
1881 $ guix build emacs --dry-run
1882 The following files would be downloaded:
1883 /gnu/store/pk3n22lbq6ydamyymqkkz7i69wiwjiwi-emacs-24.3
1884 /gnu/store/2ygn4ncnhrpr61rssa6z0d9x22si0va3-libjpeg-8d
1885 /gnu/store/71yz6lgx4dazma9dwn2mcjxaah9w77jq-cairo-1.12.16
1886 /gnu/store/7zdhgp0n1518lvfn8mb96sxqfmvqrl7v-libxrender-0.9.7
1891 This indicates that substitutes from @code{hydra.gnu.org} are usable and
1892 will be downloaded, when possible, for future builds.
1894 Guix ignores substitutes that are not signed, or that are not signed by
1895 one of the keys listed in the ACL. It also detects and raises an error
1896 when attempting to use a substitute that has been tampered with.
1899 Substitutes are downloaded over HTTP or HTTPS.
1900 The @code{http_proxy} environment
1901 variable can be set in the environment of @command{guix-daemon} and is
1902 honored for downloads of substitutes. Note that the value of
1903 @code{http_proxy} in the environment where @command{guix build},
1904 @command{guix package}, and other client commands are run has
1905 @emph{absolutely no effect}.
1907 When using HTTPS, the server's X.509 certificate is @emph{not} validated
1908 (in other words, the server is not authenticated), contrary to what
1909 HTTPS clients such as Web browsers usually do. This is because Guix
1910 authenticates substitute information itself, as explained above, which
1911 is what we care about (whereas X.509 certificates are about
1912 authenticating bindings between domain names and public keys.)
1914 The substitute mechanism can be disabled globally by running
1915 @code{guix-daemon} with @code{--no-substitutes} (@pxref{Invoking
1916 guix-daemon}). It can also be disabled temporarily by passing the
1917 @code{--no-substitutes} option to @command{guix package}, @command{guix
1918 build}, and other command-line tools.
1921 @unnumberedsubsec On Trusting Binaries
1923 Today, each individual's control over their own computing is at the
1924 mercy of institutions, corporations, and groups with enough power and
1925 determination to subvert the computing infrastructure and exploit its
1926 weaknesses. While using @code{hydra.gnu.org} substitutes can be
1927 convenient, we encourage users to also build on their own, or even run
1928 their own build farm, such that @code{hydra.gnu.org} is less of an
1929 interesting target. One way to help is by publishing the software you
1930 build using @command{guix publish} so that others have one more choice
1931 of server to download substitutes from (@pxref{Invoking guix publish}).
1933 Guix has the foundations to maximize build reproducibility
1934 (@pxref{Features}). In most cases, independent builds of a given
1935 package or derivation should yield bit-identical results. Thus, through
1936 a diverse set of independent package builds, we can strengthen the
1937 integrity of our systems. The @command{guix challenge} command aims to
1938 help users assess substitute servers, and to assist developers in
1939 finding out about non-deterministic package builds (@pxref{Invoking guix
1940 challenge}). Similarly, the @option{--check} option of @command{guix
1941 build} allows users to check whether previously-installed substitutes
1942 are genuine by rebuilding them locally (@pxref{build-check,
1943 @command{guix build --check}}).
1945 In the future, we want Guix to have support to publish and retrieve
1946 binaries to/from other users, in a peer-to-peer fashion. If you would
1947 like to discuss this project, join us on @email{guix-devel@@gnu.org}.
1950 @node Packages with Multiple Outputs
1951 @section Packages with Multiple Outputs
1953 @cindex multiple-output packages
1954 @cindex package outputs
1956 Often, packages defined in Guix have a single @dfn{output}---i.e., the
1957 source package leads to exactly one directory in the store. When running
1958 @command{guix package -i glibc}, one installs the default output of the
1959 GNU libc package; the default output is called @code{out}, but its name
1960 can be omitted as shown in this command. In this particular case, the
1961 default output of @code{glibc} contains all the C header files, shared
1962 libraries, static libraries, Info documentation, and other supporting
1965 Sometimes it is more appropriate to separate the various types of files
1966 produced from a single source package into separate outputs. For
1967 instance, the GLib C library (used by GTK+ and related packages)
1968 installs more than 20 MiB of reference documentation as HTML pages.
1969 To save space for users who do not need it, the documentation goes to a
1970 separate output, called @code{doc}. To install the main GLib output,
1971 which contains everything but the documentation, one would run:
1974 guix package -i glib
1977 The command to install its documentation is:
1980 guix package -i glib:doc
1983 Some packages install programs with different ``dependency footprints''.
1984 For instance, the WordNet package installs both command-line tools and
1985 graphical user interfaces (GUIs). The former depend solely on the C
1986 library, whereas the latter depend on Tcl/Tk and the underlying X
1987 libraries. In this case, we leave the command-line tools in the default
1988 output, whereas the GUIs are in a separate output. This allows users
1989 who do not need the GUIs to save space. The @command{guix size} command
1990 can help find out about such situations (@pxref{Invoking guix size}).
1991 @command{guix graph} can also be helpful (@pxref{Invoking guix graph}).
1993 There are several such multiple-output packages in the GNU distribution.
1994 Other conventional output names include @code{lib} for libraries and
1995 possibly header files, @code{bin} for stand-alone programs, and
1996 @code{debug} for debugging information (@pxref{Installing Debugging
1997 Files}). The outputs of a packages are listed in the third column of
1998 the output of @command{guix package --list-available} (@pxref{Invoking
2002 @node Invoking guix gc
2003 @section Invoking @command{guix gc}
2005 @cindex garbage collector
2006 Packages that are installed, but not used, may be @dfn{garbage-collected}.
2007 The @command{guix gc} command allows users to explicitly run the garbage
2008 collector to reclaim space from the @file{/gnu/store} directory. It is
2009 the @emph{only} way to remove files from @file{/gnu/store}---removing
2010 files or directories manually may break it beyond repair!
2012 The garbage collector has a set of known @dfn{roots}: any file under
2013 @file{/gnu/store} reachable from a root is considered @dfn{live} and
2014 cannot be deleted; any other file is considered @dfn{dead} and may be
2015 deleted. The set of garbage collector roots includes default user
2016 profiles, and may be augmented with @command{guix build --root}, for
2017 example (@pxref{Invoking guix build}).
2019 Prior to running @code{guix gc --collect-garbage} to make space, it is
2020 often useful to remove old generations from user profiles; that way, old
2021 package builds referenced by those generations can be reclaimed. This
2022 is achieved by running @code{guix package --delete-generations}
2023 (@pxref{Invoking guix package}).
2025 The @command{guix gc} command has three modes of operation: it can be
2026 used to garbage-collect any dead files (the default), to delete specific
2027 files (the @code{--delete} option), to print garbage-collector
2028 information, or for more advanced queries. The garbage collection
2029 options are as follows:
2032 @item --collect-garbage[=@var{min}]
2033 @itemx -C [@var{min}]
2034 Collect garbage---i.e., unreachable @file{/gnu/store} files and
2035 sub-directories. This is the default operation when no option is
2038 When @var{min} is given, stop once @var{min} bytes have been collected.
2039 @var{min} may be a number of bytes, or it may include a unit as a
2040 suffix, such as @code{MiB} for mebibytes and @code{GB} for gigabytes
2041 (@pxref{Block size, size specifications,, coreutils, GNU Coreutils}).
2043 When @var{min} is omitted, collect all the garbage.
2045 @item --free-space=@var{free}
2046 @itemx -F @var{free}
2047 Collect garbage until @var{free} space is available under
2048 @file{/gnu/store}, if possible; @var{free} denotes storage space, such
2049 as @code{500MiB}, as described above.
2051 When @var{free} or more is already available in @file{/gnu/store}, do
2052 nothing and exit immediately.
2056 Attempt to delete all the store files and directories specified as
2057 arguments. This fails if some of the files are not in the store, or if
2058 they are still live.
2060 @item --list-failures
2061 List store items corresponding to cached build failures.
2063 This prints nothing unless the daemon was started with
2064 @option{--cache-failures} (@pxref{Invoking guix-daemon,
2065 @option{--cache-failures}}).
2067 @item --clear-failures
2068 Remove the specified store items from the failed-build cache.
2070 Again, this option only makes sense when the daemon is started with
2071 @option{--cache-failures}. Otherwise, it does nothing.
2074 Show the list of dead files and directories still present in the
2075 store---i.e., files and directories no longer reachable from any root.
2078 Show the list of live store files and directories.
2082 In addition, the references among existing store files can be queried:
2088 List the references (respectively, the referrers) of store files given
2094 List the requisites of the store files passed as arguments. Requisites
2095 include the store files themselves, their references, and the references
2096 of these, recursively. In other words, the returned list is the
2097 @dfn{transitive closure} of the store files.
2099 @xref{Invoking guix size}, for a tool to profile the size of the closure
2100 of an element. @xref{Invoking guix graph}, for a tool to visualize
2101 the graph of references.
2105 Lastly, the following options allow you to check the integrity of the
2106 store and to control disk usage.
2110 @item --verify[=@var{options}]
2111 @cindex integrity, of the store
2112 @cindex integrity checking
2113 Verify the integrity of the store.
2115 By default, make sure that all the store items marked as valid in the
2116 database of the daemon actually exist in @file{/gnu/store}.
2118 When provided, @var{options} must be a comma-separated list containing one
2119 or more of @code{contents} and @code{repair}.
2121 When passing @option{--verify=contents}, the daemon computse the
2122 content hash of each store item and compares it against its hash in the
2123 database. Hash mismatches are reported as data corruptions. Because it
2124 traverses @emph{all the files in the store}, this command can take a
2125 long time, especially on systems with a slow disk drive.
2127 @cindex repairing the store
2128 Using @option{--verify=repair} or @option{--verify=contents,repair}
2129 causes the daemon to try to repair corrupt store items by fetching
2130 substitutes for them (@pxref{Substitutes}). Because repairing is not
2131 atomic, and thus potentially dangerous, it is available only to the
2132 system administrator.
2135 @cindex deduplication
2136 Optimize the store by hard-linking identical files---this is
2137 @dfn{deduplication}.
2139 The daemon performs deduplication after each successful build or archive
2140 import, unless it was started with @code{--disable-deduplication}
2141 (@pxref{Invoking guix-daemon, @code{--disable-deduplication}}). Thus,
2142 this option is primarily useful when the daemon was running with
2143 @code{--disable-deduplication}.
2147 @node Invoking guix pull
2148 @section Invoking @command{guix pull}
2150 Packages are installed or upgraded to the latest version available in
2151 the distribution currently available on your local machine. To update
2152 that distribution, along with the Guix tools, you must run @command{guix
2153 pull}: the command downloads the latest Guix source code and package
2154 descriptions, and deploys it.
2156 On completion, @command{guix package} will use packages and package
2157 versions from this just-retrieved copy of Guix. Not only that, but all
2158 the Guix commands and Scheme modules will also be taken from that latest
2159 version. New @command{guix} sub-commands added by the update also
2162 Any user can update their Guix copy using @command{guix pull}, and the
2163 effect is limited to the user who run @command{guix pull}. For
2164 instance, when user @code{root} runs @command{guix pull}, this has no
2165 effect on the version of Guix that user @code{alice} sees, and vice
2166 versa@footnote{Under the hood, @command{guix pull} updates the
2167 @file{~/.config/guix/latest} symbolic link to point to the latest Guix,
2168 and the @command{guix} command loads code from there.}.
2170 The @command{guix pull} command is usually invoked with no arguments,
2171 but it supports the following options:
2175 Produce verbose output, writing build logs to the standard error output.
2177 @item --url=@var{url}
2178 Download the source tarball of Guix from @var{url}.
2180 By default, the tarball is taken from its canonical address at
2181 @code{gnu.org}, for the stable branch of Guix.
2184 Use the bootstrap Guile to build the latest Guix. This option is only
2185 useful to Guix developers.
2189 @node Invoking guix archive
2190 @section Invoking @command{guix archive}
2192 The @command{guix archive} command allows users to @dfn{export} files
2193 from the store into a single archive, and to later @dfn{import} them.
2194 In particular, it allows store files to be transferred from one machine
2195 to the store on another machine.
2197 To export store files as an archive to standard output, run:
2200 guix archive --export @var{options} @var{specifications}...
2203 @var{specifications} may be either store file names or package
2204 specifications, as for @command{guix package} (@pxref{Invoking guix
2205 package}). For instance, the following command creates an archive
2206 containing the @code{gui} output of the @code{git} package and the main
2207 output of @code{emacs}:
2210 guix archive --export git:gui /gnu/store/...-emacs-24.3 > great.nar
2213 If the specified packages are not built yet, @command{guix archive}
2214 automatically builds them. The build process may be controlled with the
2215 common build options (@pxref{Common Build Options}).
2217 To transfer the @code{emacs} package to a machine connected over SSH,
2221 guix archive --export -r emacs | ssh the-machine guix archive --import
2225 Similarly, a complete user profile may be transferred from one machine
2226 to another like this:
2229 guix archive --export -r $(readlink -f ~/.guix-profile) | \
2230 ssh the-machine guix-archive --import
2234 However, note that, in both examples, all of @code{emacs} and the
2235 profile as well as all of their dependencies are transferred (due to
2236 @code{-r}), regardless of what is already available in the store on the
2237 target machine. The @code{--missing} option can help figure out which
2238 items are missing from the target store.
2240 Archives are stored in the ``Nix archive'' or ``Nar'' format, which is
2241 comparable in spirit to `tar', but with a few noteworthy differences
2242 that make it more appropriate for our purposes. First, rather than
2243 recording all Unix metadata for each file, the Nar format only mentions
2244 the file type (regular, directory, or symbolic link); Unix permissions
2245 and owner/group are dismissed. Second, the order in which directory
2246 entries are stored always follows the order of file names according to
2247 the C locale collation order. This makes archive production fully
2250 When exporting, the daemon digitally signs the contents of the archive,
2251 and that digital signature is appended. When importing, the daemon
2252 verifies the signature and rejects the import in case of an invalid
2253 signature or if the signing key is not authorized.
2254 @c FIXME: Add xref to daemon doc about signatures.
2256 The main options are:
2260 Export the specified store files or packages (see below.) Write the
2261 resulting archive to the standard output.
2263 Dependencies are @emph{not} included in the output, unless
2264 @code{--recursive} is passed.
2268 When combined with @code{--export}, this instructs @command{guix
2269 archive} to include dependencies of the given items in the archive.
2270 Thus, the resulting archive is self-contained: it contains the closure
2271 of the exported store items.
2274 Read an archive from the standard input, and import the files listed
2275 therein into the store. Abort if the archive has an invalid digital
2276 signature, or if it is signed by a public key not among the authorized
2277 keys (see @code{--authorize} below.)
2280 Read a list of store file names from the standard input, one per line,
2281 and write on the standard output the subset of these files missing from
2284 @item --generate-key[=@var{parameters}]
2285 @cindex signing, archives
2286 Generate a new key pair for the daemon. This is a prerequisite before
2287 archives can be exported with @code{--export}. Note that this operation
2288 usually takes time, because it needs to gather enough entropy to
2289 generate the key pair.
2291 The generated key pair is typically stored under @file{/etc/guix}, in
2292 @file{signing-key.pub} (public key) and @file{signing-key.sec} (private
2293 key, which must be kept secret.) When @var{parameters} is omitted,
2294 an ECDSA key using the Ed25519 curve is generated, or, for Libgcrypt
2295 versions before 1.6.0, it is a 4096-bit RSA key.
2296 Alternatively, @var{parameters} can specify
2297 @code{genkey} parameters suitable for Libgcrypt (@pxref{General
2298 public-key related Functions, @code{gcry_pk_genkey},, gcrypt, The
2299 Libgcrypt Reference Manual}).
2302 @cindex authorizing, archives
2303 Authorize imports signed by the public key passed on standard input.
2304 The public key must be in ``s-expression advanced format''---i.e., the
2305 same format as the @file{signing-key.pub} file.
2307 The list of authorized keys is kept in the human-editable file
2308 @file{/etc/guix/acl}. The file contains
2309 @url{http://people.csail.mit.edu/rivest/Sexp.txt, ``advanced-format
2310 s-expressions''} and is structured as an access-control list in the
2311 @url{http://theworld.com/~cme/spki.txt, Simple Public-Key Infrastructure
2314 @item --extract=@var{directory}
2315 @itemx -x @var{directory}
2316 Read a single-item archive as served by substitute servers
2317 (@pxref{Substitutes}) and extract it to @var{directory}. This is a
2318 low-level operation needed in only very narrow use cases; see below.
2320 For example, the following command extracts the substitute for Emacs
2321 served by @code{hydra.gnu.org} to @file{/tmp/emacs}:
2325 https://hydra.gnu.org/nar/@dots{}-emacs-24.5 \
2326 | bunzip2 | guix archive -x /tmp/emacs
2329 Single-item archives are different from multiple-item archives produced
2330 by @command{guix archive --export}; they contain a single store item,
2331 and they do @emph{not} embed a signature. Thus this operation does
2332 @emph{no} signature verification and its output should be considered
2335 The primary purpose of this operation is to facilitate inspection of
2336 archive contents coming from possibly untrusted substitute servers.
2340 @c *********************************************************************
2343 @c *********************************************************************
2344 @node Programming Interface
2345 @chapter Programming Interface
2347 GNU Guix provides several Scheme programming interfaces (APIs) to
2348 define, build, and query packages. The first interface allows users to
2349 write high-level package definitions. These definitions refer to
2350 familiar packaging concepts, such as the name and version of a package,
2351 its build system, and its dependencies. These definitions can then be
2352 turned into concrete build actions.
2354 Build actions are performed by the Guix daemon, on behalf of users. In a
2355 standard setup, the daemon has write access to the store---the
2356 @file{/gnu/store} directory---whereas users do not. The recommended
2357 setup also has the daemon perform builds in chroots, under a specific
2358 build users, to minimize interference with the rest of the system.
2361 Lower-level APIs are available to interact with the daemon and the
2362 store. To instruct the daemon to perform a build action, users actually
2363 provide it with a @dfn{derivation}. A derivation is a low-level
2364 representation of the build actions to be taken, and the environment in
2365 which they should occur---derivations are to package definitions what
2366 assembly is to C programs. The term ``derivation'' comes from the fact
2367 that build results @emph{derive} from them.
2369 This chapter describes all these APIs in turn, starting from high-level
2370 package definitions.
2373 * Defining Packages:: Defining new packages.
2374 * Build Systems:: Specifying how packages are built.
2375 * The Store:: Manipulating the package store.
2376 * Derivations:: Low-level interface to package derivations.
2377 * The Store Monad:: Purely functional interface to the store.
2378 * G-Expressions:: Manipulating build expressions.
2381 @node Defining Packages
2382 @section Defining Packages
2384 The high-level interface to package definitions is implemented in the
2385 @code{(guix packages)} and @code{(guix build-system)} modules. As an
2386 example, the package definition, or @dfn{recipe}, for the GNU Hello
2387 package looks like this:
2390 (define-module (gnu packages hello)
2391 #:use-module (guix packages)
2392 #:use-module (guix download)
2393 #:use-module (guix build-system gnu)
2394 #:use-module (guix licenses)
2395 #:use-module (gnu packages gawk))
2397 (define-public hello
2403 (uri (string-append "mirror://gnu/hello/hello-" version
2407 "0ssi1wpaf7plaswqqjwigppsg5fyh99vdlb9kzl7c9lng89ndq1i"))))
2408 (build-system gnu-build-system)
2409 (arguments '(#:configure-flags '("--enable-silent-rules")))
2410 (inputs `(("gawk" ,gawk)))
2411 (synopsis "Hello, GNU world: An example GNU package")
2412 (description "Guess what GNU Hello prints!")
2413 (home-page "http://www.gnu.org/software/hello/")
2418 Without being a Scheme expert, the reader may have guessed the meaning
2419 of the various fields here. This expression binds the variable
2420 @code{hello} to a @code{<package>} object, which is essentially a record
2421 (@pxref{SRFI-9, Scheme records,, guile, GNU Guile Reference Manual}).
2422 This package object can be inspected using procedures found in the
2423 @code{(guix packages)} module; for instance, @code{(package-name hello)}
2424 returns---surprise!---@code{"hello"}.
2426 With luck, you may be able to import part or all of the definition of
2427 the package you are interested in from another repository, using the
2428 @code{guix import} command (@pxref{Invoking guix import}).
2430 In the example above, @var{hello} is defined in a module of its own,
2431 @code{(gnu packages hello)}. Technically, this is not strictly
2432 necessary, but it is convenient to do so: all the packages defined in
2433 modules under @code{(gnu packages @dots{})} are automatically known to
2434 the command-line tools (@pxref{Package Modules}).
2436 There are a few points worth noting in the above package definition:
2440 The @code{source} field of the package is an @code{<origin>} object
2441 (@pxref{origin Reference}, for the complete reference).
2442 Here, the @code{url-fetch} method from @code{(guix download)} is used,
2443 meaning that the source is a file to be downloaded over FTP or HTTP.
2445 The @code{mirror://gnu} prefix instructs @code{url-fetch} to use one of
2446 the GNU mirrors defined in @code{(guix download)}.
2448 The @code{sha256} field specifies the expected SHA256 hash of the file
2449 being downloaded. It is mandatory, and allows Guix to check the
2450 integrity of the file. The @code{(base32 @dots{})} form introduces the
2451 base32 representation of the hash. You can obtain this information with
2452 @code{guix download} (@pxref{Invoking guix download}) and @code{guix
2453 hash} (@pxref{Invoking guix hash}).
2456 When needed, the @code{origin} form can also have a @code{patches} field
2457 listing patches to be applied, and a @code{snippet} field giving a
2458 Scheme expression to modify the source code.
2461 @cindex GNU Build System
2462 The @code{build-system} field specifies the procedure to build the
2463 package (@pxref{Build Systems}). Here, @var{gnu-build-system}
2464 represents the familiar GNU Build System, where packages may be
2465 configured, built, and installed with the usual @code{./configure &&
2466 make && make check && make install} command sequence.
2469 The @code{arguments} field specifies options for the build system
2470 (@pxref{Build Systems}). Here it is interpreted by
2471 @var{gnu-build-system} as a request run @file{configure} with the
2472 @code{--enable-silent-rules} flag.
2478 What about these quote (@code{'}) characters? They are Scheme syntax to
2479 introduce a literal list; @code{'} is synonymous with @code{quote}.
2480 @xref{Expression Syntax, quoting,, guile, GNU Guile Reference Manual},
2481 for details. Here the value of the @code{arguments} field is a list of
2482 arguments passed to the build system down the road, as with @code{apply}
2483 (@pxref{Fly Evaluation, @code{apply},, guile, GNU Guile Reference
2486 The hash-colon (@code{#:}) sequence defines a Scheme @dfn{keyword}
2487 (@pxref{Keywords,,, guile, GNU Guile Reference Manual}), and
2488 @code{#:configure-flags} is a keyword used to pass a keyword argument
2489 to the build system (@pxref{Coding With Keywords,,, guile, GNU Guile
2493 The @code{inputs} field specifies inputs to the build process---i.e.,
2494 build-time or run-time dependencies of the package. Here, we define an
2495 input called @code{"gawk"} whose value is that of the @var{gawk}
2496 variable; @var{gawk} is itself bound to a @code{<package>} object.
2498 @cindex backquote (quasiquote)
2501 @cindex comma (unquote)
2505 @findex unquote-splicing
2506 Again, @code{`} (a backquote, synonymous with @code{quasiquote}) allows
2507 us to introduce a literal list in the @code{inputs} field, while
2508 @code{,} (a comma, synonymous with @code{unquote}) allows us to insert a
2509 value in that list (@pxref{Expression Syntax, unquote,, guile, GNU Guile
2512 Note that GCC, Coreutils, Bash, and other essential tools do not need to
2513 be specified as inputs here. Instead, @var{gnu-build-system} takes care
2514 of ensuring that they are present (@pxref{Build Systems}).
2516 However, any other dependencies need to be specified in the
2517 @code{inputs} field. Any dependency not specified here will simply be
2518 unavailable to the build process, possibly leading to a build failure.
2521 @xref{package Reference}, for a full description of possible fields.
2523 Once a package definition is in place, the
2524 package may actually be built using the @code{guix build} command-line
2525 tool (@pxref{Invoking guix build}). You can easily jump back to the
2526 package definition using the @command{guix edit} command
2527 (@pxref{Invoking guix edit}).
2528 @xref{Packaging Guidelines}, for
2529 more information on how to test package definitions, and
2530 @ref{Invoking guix lint}, for information on how to check a definition
2531 for style conformance.
2533 Finally, updating the package definition to a new upstream version
2534 can be partly automated by the @command{guix refresh} command
2535 (@pxref{Invoking guix refresh}).
2537 Behind the scenes, a derivation corresponding to the @code{<package>}
2538 object is first computed by the @code{package-derivation} procedure.
2539 That derivation is stored in a @code{.drv} file under @file{/gnu/store}.
2540 The build actions it prescribes may then be realized by using the
2541 @code{build-derivations} procedure (@pxref{The Store}).
2543 @deffn {Scheme Procedure} package-derivation @var{store} @var{package} [@var{system}]
2544 Return the @code{<derivation>} object of @var{package} for @var{system}
2545 (@pxref{Derivations}).
2547 @var{package} must be a valid @code{<package>} object, and @var{system}
2548 must be a string denoting the target system type---e.g.,
2549 @code{"x86_64-linux"} for an x86_64 Linux-based GNU system. @var{store}
2550 must be a connection to the daemon, which operates on the store
2551 (@pxref{The Store}).
2555 @cindex cross-compilation
2556 Similarly, it is possible to compute a derivation that cross-builds a
2557 package for some other system:
2559 @deffn {Scheme Procedure} package-cross-derivation @var{store} @
2560 @var{package} @var{target} [@var{system}]
2561 Return the @code{<derivation>} object of @var{package} cross-built from
2562 @var{system} to @var{target}.
2564 @var{target} must be a valid GNU triplet denoting the target hardware
2565 and operating system, such as @code{"mips64el-linux-gnu"}
2566 (@pxref{Configuration Names, GNU configuration triplets,, configure, GNU
2567 Configure and Build System}).
2571 * package Reference :: The package data type.
2572 * origin Reference:: The origin data type.
2576 @node package Reference
2577 @subsection @code{package} Reference
2579 This section summarizes all the options available in @code{package}
2580 declarations (@pxref{Defining Packages}).
2582 @deftp {Data Type} package
2583 This is the data type representing a package recipe.
2587 The name of the package, as a string.
2589 @item @code{version}
2590 The version of the package, as a string.
2593 An object telling how the source code for the package should be
2594 acquired. Most of the time, this is an @code{origin} object, which
2595 denotes a file fetched from the Internet (@pxref{origin Reference}). It
2596 can also be any other ``file-like'' object such as a @code{local-file},
2597 which denotes a file from the local file system (@pxref{G-Expressions,
2598 @code{local-file}}).
2600 @item @code{build-system}
2601 The build system that should be used to build the package (@pxref{Build
2604 @item @code{arguments} (default: @code{'()})
2605 The arguments that should be passed to the build system. This is a
2606 list, typically containing sequential keyword-value pairs.
2608 @item @code{inputs} (default: @code{'()})
2609 @itemx @code{native-inputs} (default: @code{'()})
2610 @itemx @code{propagated-inputs} (default: @code{'()})
2611 @cindex inputs, of packages
2612 These fields list dependencies of the package. Each one is a list of
2613 tuples, where each tuple has a label for the input (a string) as its
2614 first element, a package, origin, or derivation as its second element,
2615 and optionally the name of the output thereof that should be used, which
2616 defaults to @code{"out"} (@pxref{Packages with Multiple Outputs}, for
2617 more on package outputs). For example, the list below specifies three
2621 `(("libffi" ,libffi)
2622 ("libunistring" ,libunistring)
2623 ("glib:bin" ,glib "bin")) ;the "bin" output of Glib
2626 @cindex cross compilation, package dependencies
2627 The distinction between @code{native-inputs} and @code{inputs} is
2628 necessary when considering cross-compilation. When cross-compiling,
2629 dependencies listed in @code{inputs} are built for the @emph{target}
2630 architecture; conversely, dependencies listed in @code{native-inputs}
2631 are built for the architecture of the @emph{build} machine.
2633 @code{native-inputs} is typically used to list tools needed at
2634 build time, but not at run time, such as Autoconf, Automake, pkg-config,
2635 Gettext, or Bison. @command{guix lint} can report likely mistakes in
2636 this area (@pxref{Invoking guix lint}).
2638 @anchor{package-propagated-inputs}
2639 Lastly, @code{propagated-inputs} is similar to @code{inputs}, but the
2640 specified packages will be automatically installed alongside the package
2641 they belong to (@pxref{package-cmd-propagated-inputs, @command{guix
2642 package}}, for information on how @command{guix package} deals with
2645 For example this is necessary when a C/C++ library needs headers of
2646 another library to compile, or when a pkg-config file refers to another
2647 one @i{via} its @code{Requires} field.
2649 Another example where @code{propagated-inputs} is useful is for languages
2650 that lack a facility to record the run-time search path akin to the
2651 @code{RUNPATH} of ELF files; this includes Guile, Python, Perl, GHC, and
2652 more. To ensure that libraries written in those languages can find
2653 library code they depend on at run time, run-time dependencies must be
2654 listed in @code{propagated-inputs} rather than @code{inputs}.
2656 @item @code{self-native-input?} (default: @code{#f})
2657 This is a Boolean field telling whether the package should use itself as
2658 a native input when cross-compiling.
2660 @item @code{outputs} (default: @code{'("out")})
2661 The list of output names of the package. @xref{Packages with Multiple
2662 Outputs}, for typical uses of additional outputs.
2664 @item @code{native-search-paths} (default: @code{'()})
2665 @itemx @code{search-paths} (default: @code{'()})
2666 A list of @code{search-path-specification} objects describing
2667 search-path environment variables honored by the package.
2669 @item @code{replacement} (default: @code{#f})
2670 This must be either @code{#f} or a package object that will be used as a
2671 @dfn{replacement} for this package. @xref{Security Updates, grafts},
2674 @item @code{synopsis}
2675 A one-line description of the package.
2677 @item @code{description}
2678 A more elaborate description of the package.
2680 @item @code{license}
2681 The license of the package; a value from @code{(guix licenses)},
2682 or a list of such values.
2684 @item @code{home-page}
2685 The URL to the home-page of the package, as a string.
2687 @item @code{supported-systems} (default: @var{%supported-systems})
2688 The list of systems supported by the package, as strings of the form
2689 @code{architecture-kernel}, for example @code{"x86_64-linux"}.
2691 @item @code{maintainers} (default: @code{'()})
2692 The list of maintainers of the package, as @code{maintainer} objects.
2694 @item @code{location} (default: source location of the @code{package} form)
2695 The source location of the package. It is useful to override this when
2696 inheriting from another package, in which case this field is not
2697 automatically corrected.
2702 @node origin Reference
2703 @subsection @code{origin} Reference
2705 This section summarizes all the options available in @code{origin}
2706 declarations (@pxref{Defining Packages}).
2708 @deftp {Data Type} origin
2709 This is the data type representing a source code origin.
2713 An object containing the URI of the source. The object type depends on
2714 the @code{method} (see below). For example, when using the
2715 @var{url-fetch} method of @code{(guix download)}, the valid @code{uri}
2716 values are: a URL represented as a string, or a list thereof.
2719 A procedure that handles the URI.
2724 @item @var{url-fetch} from @code{(guix download)}
2725 download a file from the HTTP, HTTPS, or FTP URL specified in the
2729 @item @var{git-fetch} from @code{(guix git-download)}
2730 clone the Git version control repository, and check out the revision
2731 specified in the @code{uri} field as a @code{git-reference} object; a
2732 @code{git-reference} looks like this:
2736 (url "git://git.debian.org/git/pkg-shadow/shadow")
2737 (commit "v4.1.5.1"))
2742 A bytevector containing the SHA-256 hash of the source. Typically the
2743 @code{base32} form is used here to generate the bytevector from a
2746 You can obtain this information using @code{guix download}
2747 (@pxref{Invoking guix download}) or @code{guix hash} (@pxref{Invoking
2750 @item @code{file-name} (default: @code{#f})
2751 The file name under which the source code should be saved. When this is
2752 @code{#f}, a sensible default value will be used in most cases. In case
2753 the source is fetched from a URL, the file name from the URL will be
2754 used. For version control checkouts, it is recommended to provide the
2755 file name explicitly because the default is not very descriptive.
2757 @item @code{patches} (default: @code{'()})
2758 A list of file names containing patches to be applied to the source.
2760 @item @code{snippet} (default: @code{#f})
2761 A G-expression (@pxref{G-Expressions}) or S-expression that will be run
2762 in the source directory. This is a convenient way to modify the source,
2763 sometimes more convenient than a patch.
2765 @item @code{patch-flags} (default: @code{'("-p1")})
2766 A list of command-line flags that should be passed to the @code{patch}
2769 @item @code{patch-inputs} (default: @code{#f})
2770 Input packages or derivations to the patching process. When this is
2771 @code{#f}, the usual set of inputs necessary for patching are provided,
2772 such as GNU@tie{}Patch.
2774 @item @code{modules} (default: @code{'()})
2775 A list of Guile modules that should be loaded during the patching
2776 process and while running the code in the @code{snippet} field.
2778 @item @code{patch-guile} (default: @code{#f})
2779 The Guile package that should be used in the patching process. When
2780 this is @code{#f}, a sensible default is used.
2786 @section Build Systems
2788 @cindex build system
2789 Each package definition specifies a @dfn{build system} and arguments for
2790 that build system (@pxref{Defining Packages}). This @code{build-system}
2791 field represents the build procedure of the package, as well as implicit
2792 dependencies of that build procedure.
2794 Build systems are @code{<build-system>} objects. The interface to
2795 create and manipulate them is provided by the @code{(guix build-system)}
2796 module, and actual build systems are exported by specific modules.
2798 @cindex bag (low-level package representation)
2799 Under the hood, build systems first compile package objects to
2800 @dfn{bags}. A @dfn{bag} is like a package, but with less
2801 ornamentation---in other words, a bag is a lower-level representation of
2802 a package, which includes all the inputs of that package, including some
2803 that were implicitly added by the build system. This intermediate
2804 representation is then compiled to a derivation (@pxref{Derivations}).
2806 Build systems accept an optional list of @dfn{arguments}. In package
2807 definitions, these are passed @i{via} the @code{arguments} field
2808 (@pxref{Defining Packages}). They are typically keyword arguments
2809 (@pxref{Optional Arguments, keyword arguments in Guile,, guile, GNU
2810 Guile Reference Manual}). The value of these arguments is usually
2811 evaluated in the @dfn{build stratum}---i.e., by a Guile process launched
2812 by the daemon (@pxref{Derivations}).
2814 The main build system is @var{gnu-build-system}, which implements the
2815 standard build procedure for GNU and many other packages. It
2816 is provided by the @code{(guix build-system gnu)} module.
2818 @defvr {Scheme Variable} gnu-build-system
2819 @var{gnu-build-system} represents the GNU Build System, and variants
2820 thereof (@pxref{Configuration, configuration and makefile conventions,,
2821 standards, GNU Coding Standards}).
2823 @cindex build phases
2824 In a nutshell, packages using it are configured, built, and installed with
2825 the usual @code{./configure && make && make check && make install}
2826 command sequence. In practice, a few additional steps are often needed.
2827 All these steps are split up in separate @dfn{phases},
2828 notably@footnote{Please see the @code{(guix build gnu-build-system)}
2829 modules for more details about the build phases.}:
2833 Unpack the source tarball, and change the current directory to the
2834 extracted source tree. If the source is actually a directory, copy it
2835 to the build tree, and enter that directory.
2837 @item patch-source-shebangs
2838 Patch shebangs encountered in source files so they refer to the right
2839 store file names. For instance, this changes @code{#!/bin/sh} to
2840 @code{#!/gnu/store/@dots{}-bash-4.3/bin/sh}.
2843 Run the @file{configure} script with a number of default options, such
2844 as @code{--prefix=/gnu/store/@dots{}}, as well as the options specified
2845 by the @code{#:configure-flags} argument.
2848 Run @code{make} with the list of flags specified with
2849 @code{#:make-flags}. If the @code{#:parallel-build?} argument is true
2850 (the default), build with @code{make -j}.
2853 Run @code{make check}, or some other target specified with
2854 @code{#:test-target}, unless @code{#:tests? #f} is passed. If the
2855 @code{#:parallel-tests?} argument is true (the default), run @code{make
2859 Run @code{make install} with the flags listed in @code{#:make-flags}.
2861 @item patch-shebangs
2862 Patch shebangs on the installed executable files.
2865 Strip debugging symbols from ELF files (unless @code{#:strip-binaries?}
2866 is false), copying them to the @code{debug} output when available
2867 (@pxref{Installing Debugging Files}).
2870 @vindex %standard-phases
2871 The build-side module @code{(guix build gnu-build-system)} defines
2872 @var{%standard-phases} as the default list of build phases.
2873 @var{%standard-phases} is a list of symbol/procedure pairs, where the
2874 procedure implements the actual phase.
2876 The list of phases used for a particular package can be changed with the
2877 @code{#:phases} parameter. For instance, passing:
2880 #:phases (modify-phases %standard-phases (delete 'configure))
2883 means that all the phases described above will be used, except the
2884 @code{configure} phase.
2886 In addition, this build system ensures that the ``standard'' environment
2887 for GNU packages is available. This includes tools such as GCC, libc,
2888 Coreutils, Bash, Make, Diffutils, grep, and sed (see the @code{(guix
2889 build-system gnu)} module for a complete list). We call these the
2890 @dfn{implicit inputs} of a package, because package definitions do not
2891 have to mention them.
2894 Other @code{<build-system>} objects are defined to support other
2895 conventions and tools used by free software packages. They inherit most
2896 of @var{gnu-build-system}, and differ mainly in the set of inputs
2897 implicitly added to the build process, and in the list of phases
2898 executed. Some of these build systems are listed below.
2900 @defvr {Scheme Variable} ant-build-system
2901 This variable is exported by @code{(guix build-system ant)}. It
2902 implements the build procedure for Java packages that can be built with
2903 @url{http://ant.apache.org/, Ant build tool}.
2905 It adds both @code{ant} and the @dfn{Java Development Kit} (JDK) as
2906 provided by the @code{icedtea} package to the set of inputs. Different
2907 packages can be specified with the @code{#:ant} and @code{#:jdk}
2908 parameters, respectively.
2910 When the original package does not provide a suitable Ant build file,
2911 the parameter @code{#:jar-name} can be used to generate a minimal Ant
2912 build file @file{build.xml} with tasks to build the specified jar
2915 The parameter @code{#:build-target} can be used to specify the Ant task
2916 that should be run during the @code{build} phase. By default the
2917 ``jar'' task will be run.
2921 @defvr {Scheme Variable} cmake-build-system
2922 This variable is exported by @code{(guix build-system cmake)}. It
2923 implements the build procedure for packages using the
2924 @url{http://www.cmake.org, CMake build tool}.
2926 It automatically adds the @code{cmake} package to the set of inputs.
2927 Which package is used can be specified with the @code{#:cmake}
2930 The @code{#:configure-flags} parameter is taken as a list of flags
2931 passed to the @command{cmake} command. The @code{#:build-type}
2932 parameter specifies in abstract terms the flags passed to the compiler;
2933 it defaults to @code{"RelWithDebInfo"} (short for ``release mode with
2934 debugging information''), which roughly means that code is compiled with
2935 @code{-O2 -g}, as is the case for Autoconf-based packages by default.
2938 @defvr {Scheme Variable} glib-or-gtk-build-system
2939 This variable is exported by @code{(guix build-system glib-or-gtk)}. It
2940 is intended for use with packages making use of GLib or GTK+.
2942 This build system adds the following two phases to the ones defined by
2943 @var{gnu-build-system}:
2946 @item glib-or-gtk-wrap
2947 The phase @code{glib-or-gtk-wrap} ensures that programs in
2948 @file{bin/} are able to find GLib ``schemas'' and
2949 @uref{https://developer.gnome.org/gtk3/stable/gtk-running.html, GTK+
2950 modules}. This is achieved by wrapping the programs in launch scripts
2951 that appropriately set the @code{XDG_DATA_DIRS} and @code{GTK_PATH}
2952 environment variables.
2954 It is possible to exclude specific package outputs from that wrapping
2955 process by listing their names in the
2956 @code{#:glib-or-gtk-wrap-excluded-outputs} parameter. This is useful
2957 when an output is known not to contain any GLib or GTK+ binaries, and
2958 where wrapping would gratuitously add a dependency of that output on
2961 @item glib-or-gtk-compile-schemas
2962 The phase @code{glib-or-gtk-compile-schemas} makes sure that all
2963 @uref{https://developer.gnome.org/gio/stable/glib-compile-schemas.html,
2964 GSettings schemas} of GLib are compiled. Compilation is performed by the
2965 @command{glib-compile-schemas} program. It is provided by the package
2966 @code{glib:bin} which is automatically imported by the build system.
2967 The @code{glib} package providing @command{glib-compile-schemas} can be
2968 specified with the @code{#:glib} parameter.
2971 Both phases are executed after the @code{install} phase.
2974 @defvr {Scheme Variable} python-build-system
2975 This variable is exported by @code{(guix build-system python)}. It
2976 implements the more or less standard build procedure used by Python
2977 packages, which consists in running @code{python setup.py build} and
2978 then @code{python setup.py install --prefix=/gnu/store/@dots{}}.
2980 For packages that install stand-alone Python programs under @code{bin/},
2981 it takes care of wrapping these programs so that their @code{PYTHONPATH}
2982 environment variable points to all the Python libraries they depend on.
2984 Which Python package is used to perform the build can be specified with
2985 the @code{#:python} parameter. This is a useful way to force a package
2986 to be built for a specific version of the Python interpreter, which
2987 might be necessary if the package is only compatible with a single
2988 interpreter version.
2991 @defvr {Scheme Variable} perl-build-system
2992 This variable is exported by @code{(guix build-system perl)}. It
2993 implements the standard build procedure for Perl packages, which either
2994 consists in running @code{perl Build.PL --prefix=/gnu/store/@dots{}},
2995 followed by @code{Build} and @code{Build install}; or in running
2996 @code{perl Makefile.PL PREFIX=/gnu/store/@dots{}}, followed by
2997 @code{make} and @code{make install}, depending on which of
2998 @code{Build.PL} or @code{Makefile.PL} is present in the package
2999 distribution. Preference is given to the former if both @code{Build.PL}
3000 and @code{Makefile.PL} exist in the package distribution. This
3001 preference can be reversed by specifying @code{#t} for the
3002 @code{#:make-maker?} parameter.
3004 The initial @code{perl Makefile.PL} or @code{perl Build.PL} invocation
3005 passes flags specified by the @code{#:make-maker-flags} or
3006 @code{#:module-build-flags} parameter, respectively.
3008 Which Perl package is used can be specified with @code{#:perl}.
3011 @defvr {Scheme Variable} r-build-system
3012 This variable is exported by @code{(guix build-system r)}. It
3013 implements the build procedure used by @uref{http://r-project.org, R}
3014 packages, which essentially is little more than running @code{R CMD
3015 INSTALL --library=/gnu/store/@dots{}} in an environment where
3016 @code{R_LIBS_SITE} contains the paths to all R package inputs. Tests
3017 are run after installation using the R function
3018 @code{tools::testInstalledPackage}.
3021 @defvr {Scheme Variable} ruby-build-system
3022 This variable is exported by @code{(guix build-system ruby)}. It
3023 implements the RubyGems build procedure used by Ruby packages, which
3024 involves running @code{gem build} followed by @code{gem install}.
3026 The @code{source} field of a package that uses this build system
3027 typically references a gem archive, since this is the format that Ruby
3028 developers use when releasing their software. The build system unpacks
3029 the gem archive, potentially patches the source, runs the test suite,
3030 repackages the gem, and installs it. Additionally, directories and
3031 tarballs may be referenced to allow building unreleased gems from Git or
3032 a traditional source release tarball.
3034 Which Ruby package is used can be specified with the @code{#:ruby}
3035 parameter. A list of additional flags to be passed to the @command{gem}
3036 command can be specified with the @code{#:gem-flags} parameter.
3039 @defvr {Scheme Variable} waf-build-system
3040 This variable is exported by @code{(guix build-system waf)}. It
3041 implements a build procedure around the @code{waf} script. The common
3042 phases---@code{configure}, @code{build}, and @code{install}---are
3043 implemented by passing their names as arguments to the @code{waf}
3046 The @code{waf} script is executed by the Python interpreter. Which
3047 Python package is used to run the script can be specified with the
3048 @code{#:python} parameter.
3051 @defvr {Scheme Variable} haskell-build-system
3052 This variable is exported by @code{(guix build-system haskell)}. It
3053 implements the Cabal build procedure used by Haskell packages, which
3054 involves running @code{runhaskell Setup.hs configure
3055 --prefix=/gnu/store/@dots{}} and @code{runhaskell Setup.hs build}.
3056 Instead of installing the package by running @code{runhaskell Setup.hs
3057 install}, to avoid trying to register libraries in the read-only
3058 compiler store directory, the build system uses @code{runhaskell
3059 Setup.hs copy}, followed by @code{runhaskell Setup.hs register}. In
3060 addition, the build system generates the package documentation by
3061 running @code{runhaskell Setup.hs haddock}, unless @code{#:haddock? #f}
3062 is passed. Optional Haddock parameters can be passed with the help of
3063 the @code{#:haddock-flags} parameter. If the file @code{Setup.hs} is
3064 not found, the build system looks for @code{Setup.lhs} instead.
3066 Which Haskell compiler is used can be specified with the @code{#:haskell}
3067 parameter which defaults to @code{ghc}.
3070 @defvr {Scheme Variable} emacs-build-system
3071 This variable is exported by @code{(guix build-system emacs)}. It
3072 implements an installation procedure similar to the packaging system
3073 of Emacs itself (@pxref{Packages,,, emacs, The GNU Emacs Manual}).
3075 It first creates the @code{@var{package}-autoloads.el} file, then it
3076 byte compiles all Emacs Lisp files. Differently from the Emacs
3077 packaging system, the Info documentation files are moved to the standard
3078 documentation directory and the @file{dir} file is deleted. Each
3079 package is installed in its own directory under
3080 @file{share/emacs/site-lisp/guix.d}.
3083 Lastly, for packages that do not need anything as sophisticated, a
3084 ``trivial'' build system is provided. It is trivial in the sense that
3085 it provides basically no support: it does not pull any implicit inputs,
3086 and does not have a notion of build phases.
3088 @defvr {Scheme Variable} trivial-build-system
3089 This variable is exported by @code{(guix build-system trivial)}.
3091 This build system requires a @code{#:builder} argument. This argument
3092 must be a Scheme expression that builds the package output(s)---as
3093 with @code{build-expression->derivation} (@pxref{Derivations,
3094 @code{build-expression->derivation}}).
3104 Conceptually, the @dfn{store} is the place where derivations that have
3105 been built successfully are stored---by default, @file{/gnu/store}.
3106 Sub-directories in the store are referred to as @dfn{store items} or
3107 sometimes @dfn{store paths}. The store has an associated database that
3108 contains information such as the store paths referred to by each store
3109 path, and the list of @emph{valid} store items---results of successful
3110 builds. This database resides in @file{@var{localstatedir}/guix/db},
3111 where @var{localstatedir} is the state directory specified @i{via}
3112 @option{--localstatedir} at configure time, usually @file{/var}.
3114 The store is @emph{always} accessed by the daemon on behalf of its clients
3115 (@pxref{Invoking guix-daemon}). To manipulate the store, clients
3116 connect to the daemon over a Unix-domain socket, send requests to it,
3117 and read the result---these are remote procedure calls, or RPCs.
3120 Users must @emph{never} modify files under @file{/gnu/store} directly.
3121 This would lead to inconsistencies and break the immutability
3122 assumptions of Guix's functional model (@pxref{Introduction}).
3124 @xref{Invoking guix gc, @command{guix gc --verify}}, for information on
3125 how to check the integrity of the store and attempt recovery from
3126 accidental modifications.
3129 The @code{(guix store)} module provides procedures to connect to the
3130 daemon, and to perform RPCs. These are described below.
3132 @deffn {Scheme Procedure} open-connection [@var{file}] [#:reserve-space? #t]
3133 Connect to the daemon over the Unix-domain socket at @var{file}. When
3134 @var{reserve-space?} is true, instruct it to reserve a little bit of
3135 extra space on the file system so that the garbage collector can still
3136 operate should the disk become full. Return a server object.
3138 @var{file} defaults to @var{%default-socket-path}, which is the normal
3139 location given the options that were passed to @command{configure}.
3142 @deffn {Scheme Procedure} close-connection @var{server}
3143 Close the connection to @var{server}.
3146 @defvr {Scheme Variable} current-build-output-port
3147 This variable is bound to a SRFI-39 parameter, which refers to the port
3148 where build and error logs sent by the daemon should be written.
3151 Procedures that make RPCs all take a server object as their first
3154 @deffn {Scheme Procedure} valid-path? @var{server} @var{path}
3155 @cindex invalid store items
3156 Return @code{#t} when @var{path} designates a valid store item and
3157 @code{#f} otherwise (an invalid item may exist on disk but still be
3158 invalid, for instance because it is the result of an aborted or failed
3161 A @code{&nix-protocol-error} condition is raised if @var{path} is not
3162 prefixed by the store directory (@file{/gnu/store}).
3165 @deffn {Scheme Procedure} add-text-to-store @var{server} @var{name} @var{text} [@var{references}]
3166 Add @var{text} under file @var{name} in the store, and return its store
3167 path. @var{references} is the list of store paths referred to by the
3168 resulting store path.
3171 @deffn {Scheme Procedure} build-derivations @var{server} @var{derivations}
3172 Build @var{derivations} (a list of @code{<derivation>} objects or
3173 derivation paths), and return when the worker is done building them.
3174 Return @code{#t} on success.
3177 Note that the @code{(guix monads)} module provides a monad as well as
3178 monadic versions of the above procedures, with the goal of making it
3179 more convenient to work with code that accesses the store (@pxref{The
3183 @i{This section is currently incomplete.}
3186 @section Derivations
3189 Low-level build actions and the environment in which they are performed
3190 are represented by @dfn{derivations}. A derivation contains the
3191 following pieces of information:
3195 The outputs of the derivation---derivations produce at least one file or
3196 directory in the store, but may produce more.
3199 The inputs of the derivations, which may be other derivations or plain
3200 files in the store (patches, build scripts, etc.)
3203 The system type targeted by the derivation---e.g., @code{x86_64-linux}.
3206 The file name of a build script in the store, along with the arguments
3210 A list of environment variables to be defined.
3214 @cindex derivation path
3215 Derivations allow clients of the daemon to communicate build actions to
3216 the store. They exist in two forms: as an in-memory representation,
3217 both on the client- and daemon-side, and as files in the store whose
3218 name end in @code{.drv}---these files are referred to as @dfn{derivation
3219 paths}. Derivations paths can be passed to the @code{build-derivations}
3220 procedure to perform the build actions they prescribe (@pxref{The
3223 The @code{(guix derivations)} module provides a representation of
3224 derivations as Scheme objects, along with procedures to create and
3225 otherwise manipulate derivations. The lowest-level primitive to create
3226 a derivation is the @code{derivation} procedure:
3228 @deffn {Scheme Procedure} derivation @var{store} @var{name} @var{builder} @
3229 @var{args} [#:outputs '("out")] [#:hash #f] [#:hash-algo #f] @
3230 [#:recursive? #f] [#:inputs '()] [#:env-vars '()] @
3231 [#:system (%current-system)] [#:references-graphs #f] @
3232 [#:allowed-references #f] [#:disallowed-references #f] @
3233 [#:leaked-env-vars #f] [#:local-build? #f] @
3234 [#:substitutable? #t]
3235 Build a derivation with the given arguments, and return the resulting
3236 @code{<derivation>} object.
3238 When @var{hash} and @var{hash-algo} are given, a
3239 @dfn{fixed-output derivation} is created---i.e., one whose result is
3240 known in advance, such as a file download. If, in addition,
3241 @var{recursive?} is true, then that fixed output may be an executable
3242 file or a directory and @var{hash} must be the hash of an archive
3243 containing this output.
3245 When @var{references-graphs} is true, it must be a list of file
3246 name/store path pairs. In that case, the reference graph of each store
3247 path is exported in the build environment in the corresponding file, in
3248 a simple text format.
3250 When @var{allowed-references} is true, it must be a list of store items
3251 or outputs that the derivation's output may refer to. Likewise,
3252 @var{disallowed-references}, if true, must be a list of things the
3253 outputs may @emph{not} refer to.
3255 When @var{leaked-env-vars} is true, it must be a list of strings
3256 denoting environment variables that are allowed to ``leak'' from the
3257 daemon's environment to the build environment. This is only applicable
3258 to fixed-output derivations---i.e., when @var{hash} is true. The main
3259 use is to allow variables such as @code{http_proxy} to be passed to
3260 derivations that download files.
3262 When @var{local-build?} is true, declare that the derivation is not a
3263 good candidate for offloading and should rather be built locally
3264 (@pxref{Daemon Offload Setup}). This is the case for small derivations
3265 where the costs of data transfers would outweigh the benefits.
3267 When @var{substitutable?} is false, declare that substitutes of the
3268 derivation's output should not be used (@pxref{Substitutes}). This is
3269 useful, for instance, when building packages that capture details of the
3270 host CPU instruction set.
3274 Here's an example with a shell script as its builder, assuming
3275 @var{store} is an open connection to the daemon, and @var{bash} points
3276 to a Bash executable in the store:
3279 (use-modules (guix utils)
3283 (let ((builder ; add the Bash script to the store
3284 (add-text-to-store store "my-builder.sh"
3285 "echo hello world > $out\n" '())))
3286 (derivation store "foo"
3287 bash `("-e" ,builder)
3288 #:inputs `((,bash) (,builder))
3289 #:env-vars '(("HOME" . "/homeless"))))
3290 @result{} #<derivation /gnu/store/@dots{}-foo.drv => /gnu/store/@dots{}-foo>
3293 As can be guessed, this primitive is cumbersome to use directly. A
3294 better approach is to write build scripts in Scheme, of course! The
3295 best course of action for that is to write the build code as a
3296 ``G-expression'', and to pass it to @code{gexp->derivation}. For more
3297 information, @pxref{G-Expressions}.
3299 Once upon a time, @code{gexp->derivation} did not exist and constructing
3300 derivations with build code written in Scheme was achieved with
3301 @code{build-expression->derivation}, documented below. This procedure
3302 is now deprecated in favor of the much nicer @code{gexp->derivation}.
3304 @deffn {Scheme Procedure} build-expression->derivation @var{store} @
3305 @var{name} @var{exp} @
3306 [#:system (%current-system)] [#:inputs '()] @
3307 [#:outputs '("out")] [#:hash #f] [#:hash-algo #f] @
3308 [#:recursive? #f] [#:env-vars '()] [#:modules '()] @
3309 [#:references-graphs #f] [#:allowed-references #f] @
3310 [#:disallowed-references #f] @
3311 [#:local-build? #f] [#:substitutable? #t] [#:guile-for-build #f]
3312 Return a derivation that executes Scheme expression @var{exp} as a
3313 builder for derivation @var{name}. @var{inputs} must be a list of
3314 @code{(name drv-path sub-drv)} tuples; when @var{sub-drv} is omitted,
3315 @code{"out"} is assumed. @var{modules} is a list of names of Guile
3316 modules from the current search path to be copied in the store,
3317 compiled, and made available in the load path during the execution of
3318 @var{exp}---e.g., @code{((guix build utils) (guix build
3319 gnu-build-system))}.
3321 @var{exp} is evaluated in an environment where @code{%outputs} is bound
3322 to a list of output/path pairs, and where @code{%build-inputs} is bound
3323 to a list of string/output-path pairs made from @var{inputs}.
3324 Optionally, @var{env-vars} is a list of string pairs specifying the name
3325 and value of environment variables visible to the builder. The builder
3326 terminates by passing the result of @var{exp} to @code{exit}; thus, when
3327 @var{exp} returns @code{#f}, the build is considered to have failed.
3329 @var{exp} is built using @var{guile-for-build} (a derivation). When
3330 @var{guile-for-build} is omitted or is @code{#f}, the value of the
3331 @code{%guile-for-build} fluid is used instead.
3333 See the @code{derivation} procedure for the meaning of
3334 @var{references-graphs}, @var{allowed-references},
3335 @var{disallowed-references}, @var{local-build?}, and
3336 @var{substitutable?}.
3340 Here's an example of a single-output derivation that creates a directory
3341 containing one file:
3344 (let ((builder '(let ((out (assoc-ref %outputs "out")))
3345 (mkdir out) ; create /gnu/store/@dots{}-goo
3346 (call-with-output-file (string-append out "/test")
3348 (display '(hello guix) p))))))
3349 (build-expression->derivation store "goo" builder))
3351 @result{} #<derivation /gnu/store/@dots{}-goo.drv => @dots{}>
3355 @node The Store Monad
3356 @section The Store Monad
3360 The procedures that operate on the store described in the previous
3361 sections all take an open connection to the build daemon as their first
3362 argument. Although the underlying model is functional, they either have
3363 side effects or depend on the current state of the store.
3365 The former is inconvenient: the connection to the build daemon has to be
3366 carried around in all those functions, making it impossible to compose
3367 functions that do not take that parameter with functions that do. The
3368 latter can be problematic: since store operations have side effects
3369 and/or depend on external state, they have to be properly sequenced.
3371 @cindex monadic values
3372 @cindex monadic functions
3373 This is where the @code{(guix monads)} module comes in. This module
3374 provides a framework for working with @dfn{monads}, and a particularly
3375 useful monad for our uses, the @dfn{store monad}. Monads are a
3376 construct that allows two things: associating ``context'' with values
3377 (in our case, the context is the store), and building sequences of
3378 computations (here computations include accesses to the store). Values
3379 in a monad---values that carry this additional context---are called
3380 @dfn{monadic values}; procedures that return such values are called
3381 @dfn{monadic procedures}.
3383 Consider this ``normal'' procedure:
3386 (define (sh-symlink store)
3387 ;; Return a derivation that symlinks the 'bash' executable.
3388 (let* ((drv (package-derivation store bash))
3389 (out (derivation->output-path drv))
3390 (sh (string-append out "/bin/bash")))
3391 (build-expression->derivation store "sh"
3392 `(symlink ,sh %output))))
3395 Using @code{(guix monads)} and @code{(guix gexp)}, it may be rewritten
3396 as a monadic function:
3399 (define (sh-symlink)
3400 ;; Same, but return a monadic value.
3401 (mlet %store-monad ((drv (package->derivation bash)))
3402 (gexp->derivation "sh"
3403 #~(symlink (string-append #$drv "/bin/bash")
3407 There are several things to note in the second version: the @code{store}
3408 parameter is now implicit and is ``threaded'' in the calls to the
3409 @code{package->derivation} and @code{gexp->derivation} monadic
3410 procedures, and the monadic value returned by @code{package->derivation}
3411 is @dfn{bound} using @code{mlet} instead of plain @code{let}.
3413 As it turns out, the call to @code{package->derivation} can even be
3414 omitted since it will take place implicitly, as we will see later
3415 (@pxref{G-Expressions}):
3418 (define (sh-symlink)
3419 (gexp->derivation "sh"
3420 #~(symlink (string-append #$bash "/bin/bash")
3425 @c <https://syntaxexclamation.wordpress.com/2014/06/26/escaping-continuations/>
3426 @c for the funny quote.
3427 Calling the monadic @code{sh-symlink} has no effect. As someone once
3428 said, ``you exit a monad like you exit a building on fire: by running''.
3429 So, to exit the monad and get the desired effect, one must use
3430 @code{run-with-store}:
3433 (run-with-store (open-connection) (sh-symlink))
3434 @result{} /gnu/store/...-sh-symlink
3437 Note that the @code{(guix monad-repl)} module extends the Guile REPL with
3438 new ``meta-commands'' to make it easier to deal with monadic procedures:
3439 @code{run-in-store}, and @code{enter-store-monad}. The former is used
3440 to ``run'' a single monadic value through the store:
3443 scheme@@(guile-user)> ,run-in-store (package->derivation hello)
3444 $1 = #<derivation /gnu/store/@dots{}-hello-2.9.drv => @dots{}>
3447 The latter enters a recursive REPL, where all the return values are
3448 automatically run through the store:
3451 scheme@@(guile-user)> ,enter-store-monad
3452 store-monad@@(guile-user) [1]> (package->derivation hello)
3453 $2 = #<derivation /gnu/store/@dots{}-hello-2.9.drv => @dots{}>
3454 store-monad@@(guile-user) [1]> (text-file "foo" "Hello!")
3455 $3 = "/gnu/store/@dots{}-foo"
3456 store-monad@@(guile-user) [1]> ,q
3457 scheme@@(guile-user)>
3461 Note that non-monadic values cannot be returned in the
3462 @code{store-monad} REPL.
3464 The main syntactic forms to deal with monads in general are provided by
3465 the @code{(guix monads)} module and are described below.
3467 @deffn {Scheme Syntax} with-monad @var{monad} @var{body} ...
3468 Evaluate any @code{>>=} or @code{return} forms in @var{body} as being
3472 @deffn {Scheme Syntax} return @var{val}
3473 Return a monadic value that encapsulates @var{val}.
3476 @deffn {Scheme Syntax} >>= @var{mval} @var{mproc} ...
3477 @dfn{Bind} monadic value @var{mval}, passing its ``contents'' to monadic
3478 procedures @var{mproc}@dots{}@footnote{This operation is commonly
3479 referred to as ``bind'', but that name denotes an unrelated procedure in
3480 Guile. Thus we use this somewhat cryptic symbol inherited from the
3481 Haskell language.}. There can be one @var{mproc} or several of them, as
3486 (with-monad %state-monad
3488 (lambda (x) (return (+ 1 x)))
3489 (lambda (x) (return (* 2 x)))))
3493 @result{} some-state
3497 @deffn {Scheme Syntax} mlet @var{monad} ((@var{var} @var{mval}) ...) @
3499 @deffnx {Scheme Syntax} mlet* @var{monad} ((@var{var} @var{mval}) ...) @
3501 Bind the variables @var{var} to the monadic values @var{mval} in
3502 @var{body}. The form (@var{var} -> @var{val}) binds @var{var} to the
3503 ``normal'' value @var{val}, as per @code{let}.
3505 @code{mlet*} is to @code{mlet} what @code{let*} is to @code{let}
3506 (@pxref{Local Bindings,,, guile, GNU Guile Reference Manual}).
3509 @deffn {Scheme System} mbegin @var{monad} @var{mexp} ...
3510 Bind @var{mexp} and the following monadic expressions in sequence,
3511 returning the result of the last expression.
3513 This is akin to @code{mlet}, except that the return values of the
3514 monadic expressions are ignored. In that sense, it is analogous to
3515 @code{begin}, but applied to monadic expressions.
3519 The @code{(guix monads)} module provides the @dfn{state monad}, which
3520 allows an additional value---the state---to be @emph{threaded} through
3521 monadic procedure calls.
3523 @defvr {Scheme Variable} %state-monad
3524 The state monad. Procedures in the state monad can access and change
3525 the state that is threaded.
3527 Consider the example below. The @code{square} procedure returns a value
3528 in the state monad. It returns the square of its argument, but also
3529 increments the current state value:
3533 (mlet %state-monad ((count (current-state)))
3534 (mbegin %state-monad
3535 (set-current-state (+ 1 count))
3538 (run-with-state (sequence %state-monad (map square (iota 3))) 0)
3543 When ``run'' through @var{%state-monad}, we obtain that additional state
3544 value, which is the number of @code{square} calls.
3547 @deffn {Monadic Procedure} current-state
3548 Return the current state as a monadic value.
3551 @deffn {Monadic Procedure} set-current-state @var{value}
3552 Set the current state to @var{value} and return the previous state as a
3556 @deffn {Monadic Procedure} state-push @var{value}
3557 Push @var{value} to the current state, which is assumed to be a list,
3558 and return the previous state as a monadic value.
3561 @deffn {Monadic Procedure} state-pop
3562 Pop a value from the current state and return it as a monadic value.
3563 The state is assumed to be a list.
3566 @deffn {Scheme Procedure} run-with-state @var{mval} [@var{state}]
3567 Run monadic value @var{mval} starting with @var{state} as the initial
3568 state. Return two values: the resulting value, and the resulting state.
3571 The main interface to the store monad, provided by the @code{(guix
3572 store)} module, is as follows.
3574 @defvr {Scheme Variable} %store-monad
3575 The store monad---an alias for @var{%state-monad}.
3577 Values in the store monad encapsulate accesses to the store. When its
3578 effect is needed, a value of the store monad must be ``evaluated'' by
3579 passing it to the @code{run-with-store} procedure (see below.)
3582 @deffn {Scheme Procedure} run-with-store @var{store} @var{mval} [#:guile-for-build] [#:system (%current-system)]
3583 Run @var{mval}, a monadic value in the store monad, in @var{store}, an
3584 open store connection.
3587 @deffn {Monadic Procedure} text-file @var{name} @var{text} [@var{references}]
3588 Return as a monadic value the absolute file name in the store of the file
3589 containing @var{text}, a string. @var{references} is a list of store items that the
3590 resulting text file refers to; it defaults to the empty list.
3593 @deffn {Monadic Procedure} interned-file @var{file} [@var{name}] @
3594 [#:recursive? #t] [#:select? (const #t)]
3595 Return the name of @var{file} once interned in the store. Use
3596 @var{name} as its store name, or the basename of @var{file} if
3597 @var{name} is omitted.
3599 When @var{recursive?} is true, the contents of @var{file} are added
3600 recursively; if @var{file} designates a flat file and @var{recursive?}
3601 is true, its contents are added, and its permission bits are kept.
3603 When @var{recursive?} is true, call @code{(@var{select?} @var{file}
3604 @var{stat})} for each directory entry, where @var{file} is the entry's
3605 absolute file name and @var{stat} is the result of @code{lstat}; exclude
3606 entries for which @var{select?} does not return true.
3608 The example below adds a file to the store, under two different names:
3611 (run-with-store (open-connection)
3612 (mlet %store-monad ((a (interned-file "README"))
3613 (b (interned-file "README" "LEGU-MIN")))
3614 (return (list a b))))
3616 @result{} ("/gnu/store/rwm@dots{}-README" "/gnu/store/44i@dots{}-LEGU-MIN")
3621 The @code{(guix packages)} module exports the following package-related
3624 @deffn {Monadic Procedure} package-file @var{package} [@var{file}] @
3625 [#:system (%current-system)] [#:target #f] @
3628 value in the absolute file name of @var{file} within the @var{output}
3629 directory of @var{package}. When @var{file} is omitted, return the name
3630 of the @var{output} directory of @var{package}. When @var{target} is
3631 true, use it as a cross-compilation target triplet.
3634 @deffn {Monadic Procedure} package->derivation @var{package} [@var{system}]
3635 @deffnx {Monadic Procedure} package->cross-derivation @var{package} @
3636 @var{target} [@var{system}]
3637 Monadic version of @code{package-derivation} and
3638 @code{package-cross-derivation} (@pxref{Defining Packages}).
3643 @section G-Expressions
3645 @cindex G-expression
3646 @cindex build code quoting
3647 So we have ``derivations'', which represent a sequence of build actions
3648 to be performed to produce an item in the store (@pxref{Derivations}).
3649 These build actions are performed when asking the daemon to actually
3650 build the derivations; they are run by the daemon in a container
3651 (@pxref{Invoking guix-daemon}).
3653 @cindex strata of code
3654 It should come as no surprise that we like to write these build actions
3655 in Scheme. When we do that, we end up with two @dfn{strata} of Scheme
3656 code@footnote{The term @dfn{stratum} in this context was coined by
3657 Manuel Serrano et al.@: in the context of their work on Hop. Oleg
3658 Kiselyov, who has written insightful
3659 @url{http://okmij.org/ftp/meta-programming/#meta-scheme, essays and code
3660 on this topic}, refers to this kind of code generation as
3661 @dfn{staging}.}: the ``host code''---code that defines packages, talks
3662 to the daemon, etc.---and the ``build code''---code that actually
3663 performs build actions, such as making directories, invoking
3664 @command{make}, etc.
3666 To describe a derivation and its build actions, one typically needs to
3667 embed build code inside host code. It boils down to manipulating build
3668 code as data, and the homoiconicity of Scheme---code has a direct
3669 representation as data---comes in handy for that. But we need more than
3670 the normal @code{quasiquote} mechanism in Scheme to construct build
3673 The @code{(guix gexp)} module implements @dfn{G-expressions}, a form of
3674 S-expressions adapted to build expressions. G-expressions, or
3675 @dfn{gexps}, consist essentially of three syntactic forms: @code{gexp},
3676 @code{ungexp}, and @code{ungexp-splicing} (or simply: @code{#~},
3677 @code{#$}, and @code{#$@@}), which are comparable to
3678 @code{quasiquote}, @code{unquote}, and @code{unquote-splicing},
3679 respectively (@pxref{Expression Syntax, @code{quasiquote},, guile,
3680 GNU Guile Reference Manual}). However, there are major differences:
3684 Gexps are meant to be written to a file and run or manipulated by other
3688 When a high-level object such as a package or derivation is unquoted
3689 inside a gexp, the result is as if its output file name had been
3693 Gexps carry information about the packages or derivations they refer to,
3694 and these dependencies are automatically added as inputs to the build
3695 processes that use them.
3698 @cindex lowering, of high-level objects in gexps
3699 This mechanism is not limited to package and derivation
3700 objects: @dfn{compilers} able to ``lower'' other high-level objects to
3701 derivations or files in the store can be defined,
3702 such that these objects can also be inserted
3703 into gexps. For example, a useful type of high-level objects that can be
3704 inserted in a gexp is ``file-like objects'', which make it easy to
3705 add files to the store and to refer to them in
3706 derivations and such (see @code{local-file} and @code{plain-file}
3709 To illustrate the idea, here is an example of a gexp:
3716 (symlink (string-append #$coreutils "/bin/ls")
3720 This gexp can be passed to @code{gexp->derivation}; we obtain a
3721 derivation that builds a directory containing exactly one symlink to
3722 @file{/gnu/store/@dots{}-coreutils-8.22/bin/ls}:
3725 (gexp->derivation "the-thing" build-exp)
3728 As one would expect, the @code{"/gnu/store/@dots{}-coreutils-8.22"} string is
3729 substituted to the reference to the @var{coreutils} package in the
3730 actual build code, and @var{coreutils} is automatically made an input to
3731 the derivation. Likewise, @code{#$output} (equivalent to @code{(ungexp
3732 output)}) is replaced by a string containing the directory name of the
3733 output of the derivation.
3735 @cindex cross compilation
3736 In a cross-compilation context, it is useful to distinguish between
3737 references to the @emph{native} build of a package---that can run on the
3738 host---versus references to cross builds of a package. To that end, the
3739 @code{#+} plays the same role as @code{#$}, but is a reference to a
3740 native package build:
3743 (gexp->derivation "vi"
3746 (system* (string-append #+coreutils "/bin/ln")
3748 (string-append #$emacs "/bin/emacs")
3749 (string-append #$output "/bin/vi")))
3750 #:target "mips64el-linux")
3754 In the example above, the native build of @var{coreutils} is used, so
3755 that @command{ln} can actually run on the host; but then the
3756 cross-compiled build of @var{emacs} is referenced.
3758 @cindex imported modules, for gexps
3759 @findex with-imported-modules
3760 Another gexp feature is @dfn{imported modules}: sometimes you want to be
3761 able to use certain Guile modules from the ``host environment'' in the
3762 gexp, so those modules should be imported in the ``build environment''.
3763 The @code{with-imported-modules} form allows you to express that:
3766 (let ((build (with-imported-modules '((guix build utils))
3768 (use-modules (guix build utils))
3769 (mkdir-p (string-append #$output "/bin"))))))
3770 (gexp->derivation "empty-dir"
3773 (display "success!\n")
3778 In this example, the @code{(guix build utils)} module is automatically
3779 pulled into the isolated build environment of our gexp, such that
3780 @code{(use-modules (guix build utils))} works as expected.
3782 The syntactic form to construct gexps is summarized below.
3784 @deffn {Scheme Syntax} #~@var{exp}
3785 @deffnx {Scheme Syntax} (gexp @var{exp})
3786 Return a G-expression containing @var{exp}. @var{exp} may contain one
3787 or more of the following forms:
3791 @itemx (ungexp @var{obj})
3792 Introduce a reference to @var{obj}. @var{obj} may have one of the
3793 supported types, for example a package or a
3794 derivation, in which case the @code{ungexp} form is replaced by its
3795 output file name---e.g., @code{"/gnu/store/@dots{}-coreutils-8.22}.
3797 If @var{obj} is a list, it is traversed and references to supported
3798 objects are substituted similarly.
3800 If @var{obj} is another gexp, its contents are inserted and its
3801 dependencies are added to those of the containing gexp.
3803 If @var{obj} is another kind of object, it is inserted as is.
3805 @item #$@var{obj}:@var{output}
3806 @itemx (ungexp @var{obj} @var{output})
3807 This is like the form above, but referring explicitly to the
3808 @var{output} of @var{obj}---this is useful when @var{obj} produces
3809 multiple outputs (@pxref{Packages with Multiple Outputs}).
3812 @itemx #+@var{obj}:output
3813 @itemx (ungexp-native @var{obj})
3814 @itemx (ungexp-native @var{obj} @var{output})
3815 Same as @code{ungexp}, but produces a reference to the @emph{native}
3816 build of @var{obj} when used in a cross compilation context.
3818 @item #$output[:@var{output}]
3819 @itemx (ungexp output [@var{output}])
3820 Insert a reference to derivation output @var{output}, or to the main
3821 output when @var{output} is omitted.
3823 This only makes sense for gexps passed to @code{gexp->derivation}.
3826 @itemx (ungexp-splicing @var{lst})
3827 Like the above, but splices the contents of @var{lst} inside the
3831 @itemx (ungexp-native-splicing @var{lst})
3832 Like the above, but refers to native builds of the objects listed in
3837 G-expressions created by @code{gexp} or @code{#~} are run-time objects
3838 of the @code{gexp?} type (see below.)
3841 @deffn {Scheme Syntax} with-imported-modules @var{modules} @var{body}@dots{}
3842 Mark the gexps defined in @var{body}@dots{} as requiring @var{modules}
3843 in their execution environment. @var{modules} must be a list of Guile
3844 module names, such as @code{'((guix build utils) (guix build gremlin))}.
3846 This form has @emph{lexical} scope: it has an effect on the gexps
3847 directly defined in @var{body}@dots{}, but not on those defined, say, in
3848 procedures called from @var{body}@dots{}.
3851 @deffn {Scheme Procedure} gexp? @var{obj}
3852 Return @code{#t} if @var{obj} is a G-expression.
3855 G-expressions are meant to be written to disk, either as code building
3856 some derivation, or as plain files in the store. The monadic procedures
3857 below allow you to do that (@pxref{The Store Monad}, for more
3858 information about monads.)
3860 @deffn {Monadic Procedure} gexp->derivation @var{name} @var{exp} @
3861 [#:system (%current-system)] [#:target #f] [#:graft? #t] @
3862 [#:hash #f] [#:hash-algo #f] @
3863 [#:recursive? #f] [#:env-vars '()] [#:modules '()] @
3864 [#:module-path @var{%load-path}] @
3865 [#:references-graphs #f] [#:allowed-references #f] @
3866 [#:disallowed-references #f] @
3867 [#:leaked-env-vars #f] @
3868 [#:script-name (string-append @var{name} "-builder")] @
3869 [#:local-build? #f] [#:substitutable? #t] [#:guile-for-build #f]
3870 Return a derivation @var{name} that runs @var{exp} (a gexp) with
3871 @var{guile-for-build} (a derivation) on @var{system}; @var{exp} is
3872 stored in a file called @var{script-name}. When @var{target} is true,
3873 it is used as the cross-compilation target triplet for packages referred
3876 @var{modules} is deprecated in favor of @code{with-imported-modules}.
3878 make @var{modules} available in the evaluation context of @var{exp};
3879 @var{modules} is a list of names of Guile modules searched in
3880 @var{module-path} to be copied in the store, compiled, and made available in
3881 the load path during the execution of @var{exp}---e.g., @code{((guix
3882 build utils) (guix build gnu-build-system))}.
3884 @var{graft?} determines whether packages referred to by @var{exp} should be grafted when
3887 When @var{references-graphs} is true, it must be a list of tuples of one of the
3891 (@var{file-name} @var{package})
3892 (@var{file-name} @var{package} @var{output})
3893 (@var{file-name} @var{derivation})
3894 (@var{file-name} @var{derivation} @var{output})
3895 (@var{file-name} @var{store-item})
3898 The right-hand-side of each element of @var{references-graphs} is automatically made
3899 an input of the build process of @var{exp}. In the build environment, each
3900 @var{file-name} contains the reference graph of the corresponding item, in a simple
3903 @var{allowed-references} must be either @code{#f} or a list of output names and packages.
3904 In the latter case, the list denotes store items that the result is allowed to
3905 refer to. Any reference to another store item will lead to a build error.
3906 Similarly for @var{disallowed-references}, which can list items that must not be
3907 referenced by the outputs.
3909 The other arguments are as for @code{derivation} (@pxref{Derivations}).
3912 @cindex file-like objects
3913 The @code{local-file}, @code{plain-file}, @code{computed-file},
3914 @code{program-file}, and @code{scheme-file} procedures below return
3915 @dfn{file-like objects}. That is, when unquoted in a G-expression,
3916 these objects lead to a file in the store. Consider this G-expression:
3919 #~(system* (string-append #$glibc "/sbin/nscd") "-f"
3920 #$(local-file "/tmp/my-nscd.conf"))
3923 The effect here is to ``intern'' @file{/tmp/my-nscd.conf} by copying it
3924 to the store. Once expanded, for instance @i{via}
3925 @code{gexp->derivation}, the G-expression refers to that copy under
3926 @file{/gnu/store}; thus, modifying or removing the file in @file{/tmp}
3927 does not have any effect on what the G-expression does.
3928 @code{plain-file} can be used similarly; it differs in that the file
3929 content is directly passed as a string.
3931 @deffn {Scheme Procedure} local-file @var{file} [@var{name}] @
3932 [#:recursive? #f] [#:select? (const #t)]
3933 Return an object representing local file @var{file} to add to the store; this
3934 object can be used in a gexp. If @var{file} is a relative file name, it is looked
3935 up relative to the source file where this form appears. @var{file} will be added to
3936 the store under @var{name}--by default the base name of @var{file}.
3938 When @var{recursive?} is true, the contents of @var{file} are added recursively; if @var{file}
3939 designates a flat file and @var{recursive?} is true, its contents are added, and its
3940 permission bits are kept.
3942 When @var{recursive?} is true, call @code{(@var{select?} @var{file}
3943 @var{stat})} for each directory entry, where @var{file} is the entry's
3944 absolute file name and @var{stat} is the result of @code{lstat}; exclude
3945 entries for which @var{select?} does not return true.
3947 This is the declarative counterpart of the @code{interned-file} monadic
3948 procedure (@pxref{The Store Monad, @code{interned-file}}).
3951 @deffn {Scheme Procedure} plain-file @var{name} @var{content}
3952 Return an object representing a text file called @var{name} with the given
3953 @var{content} (a string) to be added to the store.
3955 This is the declarative counterpart of @code{text-file}.
3958 @deffn {Scheme Procedure} computed-file @var{name} @var{gexp} @
3959 [#:options '(#:local-build? #t)]
3960 Return an object representing the store item @var{name}, a file or
3961 directory computed by @var{gexp}. @var{options}
3962 is a list of additional arguments to pass to @code{gexp->derivation}.
3964 This is the declarative counterpart of @code{gexp->derivation}.
3967 @deffn {Monadic Procedure} gexp->script @var{name} @var{exp}
3968 Return an executable script @var{name} that runs @var{exp} using
3969 @var{guile}, with @var{exp}'s imported modules in its search path.
3971 The example below builds a script that simply invokes the @command{ls}
3975 (use-modules (guix gexp) (gnu packages base))
3977 (gexp->script "list-files"
3978 #~(execl (string-append #$coreutils "/bin/ls")
3982 When ``running'' it through the store (@pxref{The Store Monad,
3983 @code{run-with-store}}), we obtain a derivation that produces an
3984 executable file @file{/gnu/store/@dots{}-list-files} along these lines:
3987 #!/gnu/store/@dots{}-guile-2.0.11/bin/guile -ds
3989 (execl (string-append "/gnu/store/@dots{}-coreutils-8.22"/bin/ls")
3994 @deffn {Scheme Procedure} program-file @var{name} @var{exp} @
3996 Return an object representing the executable store item @var{name} that
3997 runs @var{gexp}. @var{guile} is the Guile package used to execute that
4000 This is the declarative counterpart of @code{gexp->script}.
4003 @deffn {Monadic Procedure} gexp->file @var{name} @var{exp} @
4004 [#:set-load-path? #t]
4005 Return a derivation that builds a file @var{name} containing @var{exp}.
4006 When @var{set-load-path?} is true, emit code in the resulting file to
4007 set @code{%load-path} and @code{%load-compiled-path} to honor
4008 @var{exp}'s imported modules.
4010 The resulting file holds references to all the dependencies of @var{exp}
4011 or a subset thereof.
4014 @deffn {Scheme Procedure} scheme-file @var{name} @var{exp}
4015 Return an object representing the Scheme file @var{name} that contains
4018 This is the declarative counterpart of @code{gexp->file}.
4021 @deffn {Monadic Procedure} text-file* @var{name} @var{text} @dots{}
4022 Return as a monadic value a derivation that builds a text file
4023 containing all of @var{text}. @var{text} may list, in addition to
4024 strings, objects of any type that can be used in a gexp: packages,
4025 derivations, local file objects, etc. The resulting store file holds
4026 references to all these.
4028 This variant should be preferred over @code{text-file} anytime the file
4029 to create will reference items from the store. This is typically the
4030 case when building a configuration file that embeds store file names,
4034 (define (profile.sh)
4035 ;; Return the name of a shell script in the store that
4036 ;; initializes the 'PATH' environment variable.
4037 (text-file* "profile.sh"
4038 "export PATH=" coreutils "/bin:"
4039 grep "/bin:" sed "/bin\n"))
4042 In this example, the resulting @file{/gnu/store/@dots{}-profile.sh} file
4043 will reference @var{coreutils}, @var{grep}, and @var{sed}, thereby
4044 preventing them from being garbage-collected during its lifetime.
4047 @deffn {Scheme Procedure} mixed-text-file @var{name} @var{text} @dots{}
4048 Return an object representing store file @var{name} containing
4049 @var{text}. @var{text} is a sequence of strings and file-like objects,
4053 (mixed-text-file "profile"
4054 "export PATH=" coreutils "/bin:" grep "/bin")
4057 This is the declarative counterpart of @code{text-file*}.
4060 Of course, in addition to gexps embedded in ``host'' code, there are
4061 also modules containing build tools. To make it clear that they are
4062 meant to be used in the build stratum, these modules are kept in the
4063 @code{(guix build @dots{})} name space.
4065 @cindex lowering, of high-level objects in gexps
4066 Internally, high-level objects are @dfn{lowered}, using their compiler,
4067 to either derivations or store items. For instance, lowering a package
4068 yields a derivation, and lowering a @code{plain-file} yields a store
4069 item. This is achieved using the @code{lower-object} monadic procedure.
4071 @deffn {Monadic Procedure} lower-object @var{obj} [@var{system}] @
4073 Return as a value in @var{%store-monad} the derivation or store item
4074 corresponding to @var{obj} for @var{system}, cross-compiling for
4075 @var{target} if @var{target} is true. @var{obj} must be an object that
4076 has an associated gexp compiler, such as a @code{<package>}.
4080 @c *********************************************************************
4084 This section describes Guix command-line utilities. Some of them are
4085 primarily targeted at developers and users who write new package
4086 definitions, while others are more generally useful. They complement
4087 the Scheme programming interface of Guix in a convenient way.
4090 * Invoking guix build:: Building packages from the command line.
4091 * Invoking guix edit:: Editing package definitions.
4092 * Invoking guix download:: Downloading a file and printing its hash.
4093 * Invoking guix hash:: Computing the cryptographic hash of a file.
4094 * Invoking guix import:: Importing package definitions.
4095 * Invoking guix refresh:: Updating package definitions.
4096 * Invoking guix lint:: Finding errors in package definitions.
4097 * Invoking guix size:: Profiling disk usage.
4098 * Invoking guix graph:: Visualizing the graph of packages.
4099 * Invoking guix environment:: Setting up development environments.
4100 * Invoking guix publish:: Sharing substitutes.
4101 * Invoking guix challenge:: Challenging substitute servers.
4102 * Invoking guix container:: Process isolation.
4105 @node Invoking guix build
4106 @section Invoking @command{guix build}
4108 The @command{guix build} command builds packages or derivations and
4109 their dependencies, and prints the resulting store paths. Note that it
4110 does not modify the user's profile---this is the job of the
4111 @command{guix package} command (@pxref{Invoking guix package}). Thus,
4112 it is mainly useful for distribution developers.
4114 The general syntax is:
4117 guix build @var{options} @var{package-or-derivation}@dots{}
4120 As an example, the following command builds the latest versions of Emacs
4121 and of Guile, displays their build logs, and finally displays the
4122 resulting directories:
4125 guix build emacs guile
4128 Similarly, the following command builds all the available packages:
4131 guix build --quiet --keep-going \
4132 `guix package -A | cut -f1,2 --output-delimiter=@@`
4135 @var{package-or-derivation} may be either the name of a package found in
4136 the software distribution such as @code{coreutils} or
4137 @code{coreutils-8.20}, or a derivation such as
4138 @file{/gnu/store/@dots{}-coreutils-8.19.drv}. In the former case, a
4139 package with the corresponding name (and optionally version) is searched
4140 for among the GNU distribution modules (@pxref{Package Modules}).
4142 Alternatively, the @code{--expression} option may be used to specify a
4143 Scheme expression that evaluates to a package; this is useful when
4144 disambiguating among several same-named packages or package variants is
4147 There may be zero or more @var{options}. The available options are
4148 described in the subsections below.
4151 * Common Build Options:: Build options for most commands.
4152 * Package Transformation Options:: Creating variants of packages.
4153 * Additional Build Options:: Options specific to 'guix build'.
4156 @node Common Build Options
4157 @subsection Common Build Options
4159 A number of options that control the build process are common to
4160 @command{guix build} and other commands that can spawn builds, such as
4161 @command{guix package} or @command{guix archive}. These are the
4166 @item --load-path=@var{directory}
4167 @itemx -L @var{directory}
4168 Add @var{directory} to the front of the package module search path
4169 (@pxref{Package Modules}).
4171 This allows users to define their own packages and make them visible to
4172 the command-line tools.
4176 Keep the build tree of failed builds. Thus, if a build fails, its build
4177 tree is kept under @file{/tmp}, in a directory whose name is shown at
4178 the end of the build log. This is useful when debugging build issues.
4182 Keep going when some of the derivations fail to build; return only once
4183 all the builds have either completed or failed.
4185 The default behavior is to stop as soon as one of the specified
4186 derivations has failed.
4190 Do not build the derivations.
4193 When substituting a pre-built binary fails, fall back to building
4196 @item --substitute-urls=@var{urls}
4197 @anchor{client-substitute-urls}
4198 Consider @var{urls} the whitespace-separated list of substitute source
4199 URLs, overriding the default list of URLs of @command{guix-daemon}
4200 (@pxref{daemon-substitute-urls,, @command{guix-daemon} URLs}).
4202 This means that substitutes may be downloaded from @var{urls}, provided
4203 they are signed by a key authorized by the system administrator
4204 (@pxref{Substitutes}).
4206 When @var{urls} is the empty string, substitutes are effectively
4209 @item --no-substitutes
4210 Do not use substitutes for build products. That is, always build things
4211 locally instead of allowing downloads of pre-built binaries
4212 (@pxref{Substitutes}).
4215 Do not ``graft'' packages. In practice, this means that package updates
4216 available as grafts are not applied. @xref{Security Updates}, for more
4217 information on grafts.
4219 @item --rounds=@var{n}
4220 Build each derivation @var{n} times in a row, and raise an error if
4221 consecutive build results are not bit-for-bit identical.
4223 This is a useful way to detect non-deterministic builds processes.
4224 Non-deterministic build processes are a problem because they make it
4225 practically impossible for users to @emph{verify} whether third-party
4226 binaries are genuine. @xref{Invoking guix challenge}, for more.
4228 Note that, currently, the differing build results are not kept around,
4229 so you will have to manually investigate in case of an error---e.g., by
4230 stashing one of the build results with @code{guix archive --export}
4231 (@pxref{Invoking guix archive}), then rebuilding, and finally comparing
4234 @item --no-build-hook
4235 Do not attempt to offload builds @i{via} the ``build hook'' of the daemon
4236 (@pxref{Daemon Offload Setup}). That is, always build things locally
4237 instead of offloading builds to remote machines.
4239 @item --max-silent-time=@var{seconds}
4240 When the build or substitution process remains silent for more than
4241 @var{seconds}, terminate it and report a build failure.
4243 @item --timeout=@var{seconds}
4244 Likewise, when the build or substitution process lasts for more than
4245 @var{seconds}, terminate it and report a build failure.
4247 By default there is no timeout. This behavior can be restored with
4250 @item --verbosity=@var{level}
4251 Use the given verbosity level. @var{level} must be an integer between 0
4252 and 5; higher means more verbose output. Setting a level of 4 or more
4253 may be helpful when debugging setup issues with the build daemon.
4255 @item --cores=@var{n}
4257 Allow the use of up to @var{n} CPU cores for the build. The special
4258 value @code{0} means to use as many CPU cores as available.
4260 @item --max-jobs=@var{n}
4262 Allow at most @var{n} build jobs in parallel. @xref{Invoking
4263 guix-daemon, @code{--max-jobs}}, for details about this option and the
4264 equivalent @command{guix-daemon} option.
4268 Behind the scenes, @command{guix build} is essentially an interface to
4269 the @code{package-derivation} procedure of the @code{(guix packages)}
4270 module, and to the @code{build-derivations} procedure of the @code{(guix
4271 derivations)} module.
4273 In addition to options explicitly passed on the command line,
4274 @command{guix build} and other @command{guix} commands that support
4275 building honor the @code{GUIX_BUILD_OPTIONS} environment variable.
4277 @defvr {Environment Variable} GUIX_BUILD_OPTIONS
4278 Users can define this variable to a list of command line options that
4279 will automatically be used by @command{guix build} and other
4280 @command{guix} commands that can perform builds, as in the example
4284 $ export GUIX_BUILD_OPTIONS="--no-substitutes -c 2 -L /foo/bar"
4287 These options are parsed independently, and the result is appended to
4288 the parsed command-line options.
4292 @node Package Transformation Options
4293 @subsection Package Transformation Options
4295 @cindex package variants
4296 Another set of command-line options supported by @command{guix build}
4297 and also @command{guix package} are @dfn{package transformation
4298 options}. These are options that make it possible to define @dfn{package
4299 variants}---for instance, packages built from different source code.
4300 This is a convenient way to create customized packages on the fly
4301 without having to type in the definitions of package variants
4302 (@pxref{Defining Packages}).
4306 @item --with-source=@var{source}
4307 Use @var{source} as the source of the corresponding package.
4308 @var{source} must be a file name or a URL, as for @command{guix
4309 download} (@pxref{Invoking guix download}).
4311 The ``corresponding package'' is taken to be the one specified on the
4312 command line the name of which matches the base of @var{source}---e.g.,
4313 if @var{source} is @code{/src/guile-2.0.10.tar.gz}, the corresponding
4314 package is @code{guile}. Likewise, the version string is inferred from
4315 @var{source}; in the previous example, it is @code{2.0.10}.
4317 This option allows users to try out versions of packages other than the
4318 one provided by the distribution. The example below downloads
4319 @file{ed-1.7.tar.gz} from a GNU mirror and uses that as the source for
4320 the @code{ed} package:
4323 guix build ed --with-source=mirror://gnu/ed/ed-1.7.tar.gz
4326 As a developer, @code{--with-source} makes it easy to test release
4330 guix build guile --with-source=../guile-2.0.9.219-e1bb7.tar.xz
4333 @dots{} or to build from a checkout in a pristine environment:
4336 $ git clone git://git.sv.gnu.org/guix.git
4337 $ guix build guix --with-source=./guix
4340 @item --with-input=@var{package}=@var{replacement}
4341 Replace dependency on @var{package} by a dependency on
4342 @var{replacement}. @var{package} must be a package name, and
4343 @var{replacement} must be a package specification such as @code{guile}
4344 or @code{guile@@1.8}.
4346 For instance, the following command builds Guix, but replaces its
4347 dependency on the current stable version of Guile with a dependency on
4348 the development version of Guile, @code{guile-next}:
4351 guix build --with-input=guile=guile-next guix
4354 This is a recursive, deep replacement. So in this example, both
4355 @code{guix} and its dependency @code{guile-json} (which also depends on
4356 @code{guile}) get rebuilt against @code{guile-next}.
4358 However, implicit inputs are left unchanged.
4361 @node Additional Build Options
4362 @subsection Additional Build Options
4364 The command-line options presented below are specific to @command{guix
4371 Build quietly, without displaying the build log. Upon completion, the
4372 build log is kept in @file{/var} (or similar) and can always be
4373 retrieved using the @option{--log-file} option.
4375 @item --file=@var{file}
4376 @itemx -f @var{file}
4378 Build the package or derivation that the code within @var{file}
4381 As an example, @var{file} might contain a package definition like this
4382 (@pxref{Defining Packages}):
4385 @verbatiminclude package-hello.scm
4388 @item --expression=@var{expr}
4389 @itemx -e @var{expr}
4390 Build the package or derivation @var{expr} evaluates to.
4392 For example, @var{expr} may be @code{(@@ (gnu packages guile)
4393 guile-1.8)}, which unambiguously designates this specific variant of
4394 version 1.8 of Guile.
4396 Alternatively, @var{expr} may be a G-expression, in which case it is used
4397 as a build program passed to @code{gexp->derivation}
4398 (@pxref{G-Expressions}).
4400 Lastly, @var{expr} may refer to a zero-argument monadic procedure
4401 (@pxref{The Store Monad}). The procedure must return a derivation as a
4402 monadic value, which is then passed through @code{run-with-store}.
4406 Build the source derivations of the packages, rather than the packages
4409 For instance, @code{guix build -S gcc} returns something like
4410 @file{/gnu/store/@dots{}-gcc-4.7.2.tar.bz2}, which is the GCC
4413 The returned source tarball is the result of applying any patches and
4414 code snippets specified in the package @code{origin} (@pxref{Defining
4418 Fetch and return the source of @var{package-or-derivation} and all their
4419 dependencies, recursively. This is a handy way to obtain a local copy
4420 of all the source code needed to build @var{packages}, allowing you to
4421 eventually build them even without network access. It is an extension
4422 of the @code{--source} option and can accept one of the following
4423 optional argument values:
4427 This value causes the @code{--sources} option to behave in the same way
4428 as the @code{--source} option.
4431 Build the source derivations of all packages, including any source that
4432 might be listed as @code{inputs}. This is the default value.
4435 $ guix build --sources tzdata
4436 The following derivations will be built:
4437 /gnu/store/@dots{}-tzdata2015b.tar.gz.drv
4438 /gnu/store/@dots{}-tzcode2015b.tar.gz.drv
4442 Build the source derivations of all packages, as well of all transitive
4443 inputs to the packages. This can be used e.g. to
4444 prefetch package source for later offline building.
4447 $ guix build --sources=transitive tzdata
4448 The following derivations will be built:
4449 /gnu/store/@dots{}-tzcode2015b.tar.gz.drv
4450 /gnu/store/@dots{}-findutils-4.4.2.tar.xz.drv
4451 /gnu/store/@dots{}-grep-2.21.tar.xz.drv
4452 /gnu/store/@dots{}-coreutils-8.23.tar.xz.drv
4453 /gnu/store/@dots{}-make-4.1.tar.xz.drv
4454 /gnu/store/@dots{}-bash-4.3.tar.xz.drv
4460 @item --system=@var{system}
4461 @itemx -s @var{system}
4462 Attempt to build for @var{system}---e.g., @code{i686-linux}---instead of
4463 the system type of the build host.
4465 An example use of this is on Linux-based systems, which can emulate
4466 different personalities. For instance, passing
4467 @code{--system=i686-linux} on an @code{x86_64-linux} system allows users
4468 to build packages in a complete 32-bit environment.
4470 @item --target=@var{triplet}
4471 @cindex cross-compilation
4472 Cross-build for @var{triplet}, which must be a valid GNU triplet, such
4473 as @code{"mips64el-linux-gnu"} (@pxref{Configuration Names, GNU
4474 configuration triplets,, configure, GNU Configure and Build System}).
4476 @anchor{build-check}
4478 @cindex determinism, checking
4479 @cindex reproducibility, checking
4480 Rebuild @var{package-or-derivation}, which are already available in the
4481 store, and raise an error if the build results are not bit-for-bit
4484 This mechanism allows you to check whether previously installed
4485 substitutes are genuine (@pxref{Substitutes}), or whether the build result
4486 of a package is deterministic. @xref{Invoking guix challenge}, for more
4487 background information and tools.
4489 When used in conjunction with @option{--keep-failed}, the differing
4490 output is kept in the store, under @file{/gnu/store/@dots{}-check}.
4491 This makes it easy to look for differences between the two results.
4495 Return the derivation paths, not the output paths, of the given
4498 @item --root=@var{file}
4499 @itemx -r @var{file}
4500 Make @var{file} a symlink to the result, and register it as a garbage
4504 Return the build log file names or URLs for the given
4505 @var{package-or-derivation}, or raise an error if build logs are
4508 This works regardless of how packages or derivations are specified. For
4509 instance, the following invocations are equivalent:
4512 guix build --log-file `guix build -d guile`
4513 guix build --log-file `guix build guile`
4514 guix build --log-file guile
4515 guix build --log-file -e '(@@ (gnu packages guile) guile-2.0)'
4518 If a log is unavailable locally, and unless @code{--no-substitutes} is
4519 passed, the command looks for a corresponding log on one of the
4520 substitute servers (as specified with @code{--substitute-urls}.)
4522 So for instance, imagine you want to see the build log of GDB on MIPS,
4523 but you are actually on an @code{x86_64} machine:
4526 $ guix build --log-file gdb -s mips64el-linux
4527 https://hydra.gnu.org/log/@dots{}-gdb-7.10
4530 You can freely access a huge library of build logs!
4534 @node Invoking guix edit
4535 @section Invoking @command{guix edit}
4537 @cindex package definition, editing
4538 So many packages, so many source files! The @command{guix edit} command
4539 facilitates the life of users and packagers by pointing their editor at
4540 the source file containing the definition of the specified packages.
4544 guix edit gcc@@4.9 vim
4548 launches the program specified in the @code{VISUAL} or in the
4549 @code{EDITOR} environment variable to view the recipe of GCC@tie{}4.9.3
4552 If you are using a Guix Git checkout (@pxref{Building from Git}), or
4553 have created your own packages on @code{GUIX_PACKAGE_PATH}
4554 (@pxref{Defining Packages}), you will be able to edit the package
4555 recipes. Otherwise, you will be able to examine the read-only recipes
4556 for packages currently in the store.
4558 If you are using Emacs, note that the Emacs user interface provides the
4559 @kbd{M-x guix-edit} command and a similar functionality in the ``package
4560 info'' and ``package list'' buffers created by the @kbd{M-x
4561 guix-search-by-name} and similar commands (@pxref{Emacs Commands}).
4564 @node Invoking guix download
4565 @section Invoking @command{guix download}
4567 When writing a package definition, developers typically need to download
4568 a source tarball, compute its SHA256 hash, and write that
4569 hash in the package definition (@pxref{Defining Packages}). The
4570 @command{guix download} tool helps with this task: it downloads a file
4571 from the given URI, adds it to the store, and prints both its file name
4572 in the store and its SHA256 hash.
4574 The fact that the downloaded file is added to the store saves bandwidth:
4575 when the developer eventually tries to build the newly defined package
4576 with @command{guix build}, the source tarball will not have to be
4577 downloaded again because it is already in the store. It is also a
4578 convenient way to temporarily stash files, which may be deleted
4579 eventually (@pxref{Invoking guix gc}).
4581 The @command{guix download} command supports the same URIs as used in
4582 package definitions. In particular, it supports @code{mirror://} URIs.
4583 @code{https} URIs (HTTP over TLS) are supported @emph{provided} the
4584 Guile bindings for GnuTLS are available in the user's environment; when
4585 they are not available, an error is raised. @xref{Guile Preparations,
4586 how to install the GnuTLS bindings for Guile,, gnutls-guile,
4587 GnuTLS-Guile}, for more information.
4589 The following option is available:
4592 @item --format=@var{fmt}
4594 Write the hash in the format specified by @var{fmt}. For more
4595 information on the valid values for @var{fmt}, @pxref{Invoking guix hash}.
4598 @node Invoking guix hash
4599 @section Invoking @command{guix hash}
4601 The @command{guix hash} command computes the SHA256 hash of a file.
4602 It is primarily a convenience tool for anyone contributing to the
4603 distribution: it computes the cryptographic hash of a file, which can be
4604 used in the definition of a package (@pxref{Defining Packages}).
4606 The general syntax is:
4609 guix hash @var{option} @var{file}
4612 @command{guix hash} has the following option:
4616 @item --format=@var{fmt}
4618 Write the hash in the format specified by @var{fmt}.
4620 Supported formats: @code{nix-base32}, @code{base32}, @code{base16}
4621 (@code{hex} and @code{hexadecimal} can be used as well).
4623 If the @option{--format} option is not specified, @command{guix hash}
4624 will output the hash in @code{nix-base32}. This representation is used
4625 in the definitions of packages.
4629 Compute the hash on @var{file} recursively.
4631 In this case, the hash is computed on an archive containing @var{file},
4632 including its children if it is a directory. Some of the metadata of
4633 @var{file} is part of the archive; for instance, when @var{file} is a
4634 regular file, the hash is different depending on whether @var{file} is
4635 executable or not. Metadata such as time stamps has no impact on the
4636 hash (@pxref{Invoking guix archive}).
4637 @c FIXME: Replace xref above with xref to an ``Archive'' section when
4641 As an example, here is how you would compute the hash of a Git checkout,
4642 which is useful when using the @code{git-fetch} method (@pxref{origin
4646 $ git clone http://example.org/foo.git
4653 @node Invoking guix import
4654 @section Invoking @command{guix import}
4656 @cindex importing packages
4657 @cindex package import
4658 @cindex package conversion
4659 The @command{guix import} command is useful for people who would like to
4660 add a package to the distribution with as little work as
4661 possible---a legitimate demand. The command knows of a few
4662 repositories from which it can ``import'' package metadata. The result
4663 is a package definition, or a template thereof, in the format we know
4664 (@pxref{Defining Packages}).
4666 The general syntax is:
4669 guix import @var{importer} @var{options}@dots{}
4672 @var{importer} specifies the source from which to import package
4673 metadata, and @var{options} specifies a package identifier and other
4674 options specific to @var{importer}. Currently, the available
4679 Import metadata for the given GNU package. This provides a template
4680 for the latest version of that GNU package, including the hash of its
4681 source tarball, and its canonical synopsis and description.
4683 Additional information such as the package dependencies and its
4684 license needs to be figured out manually.
4686 For example, the following command returns a package definition for
4690 guix import gnu hello
4693 Specific command-line options are:
4696 @item --key-download=@var{policy}
4697 As for @code{guix refresh}, specify the policy to handle missing OpenPGP
4698 keys when verifying the package signature. @xref{Invoking guix
4699 refresh, @code{--key-download}}.
4704 Import metadata from the @uref{https://pypi.python.org/, Python Package
4705 Index}@footnote{This functionality requires Guile-JSON to be installed.
4706 @xref{Requirements}.}. Information is taken from the JSON-formatted
4707 description available at @code{pypi.python.org} and usually includes all
4708 the relevant information, including package dependencies. For maximum
4709 efficiency, it is recommended to install the @command{unzip} utility, so
4710 that the importer can unzip Python wheels and gather data from them.
4712 The command below imports metadata for the @code{itsdangerous} Python
4716 guix import pypi itsdangerous
4721 Import metadata from @uref{https://rubygems.org/,
4722 RubyGems}@footnote{This functionality requires Guile-JSON to be
4723 installed. @xref{Requirements}.}. Information is taken from the
4724 JSON-formatted description available at @code{rubygems.org} and includes
4725 most relevant information, including runtime dependencies. There are
4726 some caveats, however. The metadata doesn't distinguish between
4727 synopses and descriptions, so the same string is used for both fields.
4728 Additionally, the details of non-Ruby dependencies required to build
4729 native extensions is unavailable and left as an exercise to the
4732 The command below imports metadata for the @code{rails} Ruby package:
4735 guix import gem rails
4740 Import metadata from @uref{https://www.metacpan.org/, MetaCPAN}@footnote{This
4741 functionality requires Guile-JSON to be installed.
4742 @xref{Requirements}.}.
4743 Information is taken from the JSON-formatted metadata provided through
4744 @uref{https://api.metacpan.org/, MetaCPAN's API} and includes most
4745 relevant information, such as module dependencies. License information
4746 should be checked closely. If Perl is available in the store, then the
4747 @code{corelist} utility will be used to filter core modules out of the
4748 list of dependencies.
4750 The command command below imports metadata for the @code{Acme::Boolean}
4754 guix import cpan Acme::Boolean
4759 @cindex Bioconductor
4760 Import metadata from @uref{http://cran.r-project.org/, CRAN}, the
4761 central repository for the @uref{http://r-project.org, GNU@tie{}R
4762 statistical and graphical environment}.
4764 Information is extracted from the @code{DESCRIPTION} file of the package.
4766 The command command below imports metadata for the @code{Cairo}
4770 guix import cran Cairo
4773 When @code{--archive=bioconductor} is added, metadata is imported from
4774 @uref{http://www.bioconductor.org/, Bioconductor}, a repository of R
4775 packages for for the analysis and comprehension of high-throughput
4776 genomic data in bioinformatics.
4778 Information is extracted from the @code{DESCRIPTION} file of a package
4779 published on the web interface of the Bioconductor SVN repository.
4781 The command below imports metadata for the @code{GenomicRanges}
4785 guix import cran --archive=bioconductor GenomicRanges
4789 Import metadata from a local copy of the source of the
4790 @uref{http://nixos.org/nixpkgs/, Nixpkgs distribution}@footnote{This
4791 relies on the @command{nix-instantiate} command of
4792 @uref{http://nixos.org/nix/, Nix}.}. Package definitions in Nixpkgs are
4793 typically written in a mixture of Nix-language and Bash code. This
4794 command only imports the high-level package structure that is written in
4795 the Nix language. It normally includes all the basic fields of a
4798 When importing a GNU package, the synopsis and descriptions are replaced
4799 by their canonical upstream variant.
4801 Usually, you will first need to do:
4804 export NIX_REMOTE=daemon
4808 so that @command{nix-instantiate} does not try to open the Nix database.
4810 As an example, the command below imports the package definition of
4811 LibreOffice (more precisely, it imports the definition of the package
4812 bound to the @code{libreoffice} top-level attribute):
4815 guix import nix ~/path/to/nixpkgs libreoffice
4820 Import metadata from the Haskell community's central package archive
4821 @uref{https://hackage.haskell.org/, Hackage}. Information is taken from
4822 Cabal files and includes all the relevant information, including package
4825 Specific command-line options are:
4830 Read a Cabal file from standard input.
4831 @item --no-test-dependencies
4833 Do not include dependencies required only by the test suites.
4834 @item --cabal-environment=@var{alist}
4835 @itemx -e @var{alist}
4836 @var{alist} is a Scheme alist defining the environment in which the
4837 Cabal conditionals are evaluated. The accepted keys are: @code{os},
4838 @code{arch}, @code{impl} and a string representing the name of a flag.
4839 The value associated with a flag has to be either the symbol
4840 @code{true} or @code{false}. The value associated with other keys
4841 has to conform to the Cabal file format definition. The default value
4842 associated with the keys @code{os}, @code{arch} and @code{impl} is
4843 @samp{linux}, @samp{x86_64} and @samp{ghc}, respectively.
4846 The command below imports metadata for the latest version of the
4847 @code{HTTP} Haskell package without including test dependencies and
4848 specifying the value of the flag @samp{network-uri} as @code{false}:
4851 guix import hackage -t -e "'((\"network-uri\" . false))" HTTP
4854 A specific package version may optionally be specified by following the
4855 package name by an at-sign and a version number as in the following example:
4858 guix import hackage mtl@@2.1.3.1
4863 Import metadata from an Emacs Lisp Package Archive (ELPA) package
4864 repository (@pxref{Packages,,, emacs, The GNU Emacs Manual}).
4866 Specific command-line options are:
4869 @item --archive=@var{repo}
4870 @itemx -a @var{repo}
4871 @var{repo} identifies the archive repository from which to retrieve the
4872 information. Currently the supported repositories and their identifiers
4876 @uref{http://elpa.gnu.org/packages, GNU}, selected by the @code{gnu}
4877 identifier. This is the default.
4880 @uref{http://stable.melpa.org/packages, MELPA-Stable}, selected by the
4881 @code{melpa-stable} identifier.
4884 @uref{http://melpa.org/packages, MELPA}, selected by the @code{melpa}
4890 The structure of the @command{guix import} code is modular. It would be
4891 useful to have more importers for other package formats, and your help
4892 is welcome here (@pxref{Contributing}).
4894 @node Invoking guix refresh
4895 @section Invoking @command{guix refresh}
4897 The primary audience of the @command{guix refresh} command is developers
4898 of the GNU software distribution. By default, it reports any packages
4899 provided by the distribution that are outdated compared to the latest
4900 upstream version, like this:
4904 gnu/packages/gettext.scm:29:13: gettext would be upgraded from 0.18.1.1 to 0.18.2.1
4905 gnu/packages/glib.scm:77:12: glib would be upgraded from 2.34.3 to 2.37.0
4908 It does so by browsing the FTP directory of each package and determining
4909 the highest version number of the source tarballs therein. The command
4910 knows how to update specific types of packages: GNU packages, ELPA
4911 packages, etc.---see the documentation for @option{--type} below. The
4912 are many packages, though, for which it lacks a method to determine
4913 whether a new upstream release is available. However, the mechanism is
4914 extensible, so feel free to get in touch with us to add a new method!
4916 When passed @code{--update}, it modifies distribution source files to
4917 update the version numbers and source tarball hashes of those package
4918 recipes (@pxref{Defining Packages}). This is achieved by downloading
4919 each package's latest source tarball and its associated OpenPGP
4920 signature, authenticating the downloaded tarball against its signature
4921 using @command{gpg}, and finally computing its hash. When the public
4922 key used to sign the tarball is missing from the user's keyring, an
4923 attempt is made to automatically retrieve it from a public key server;
4924 when this is successful, the key is added to the user's keyring; otherwise,
4925 @command{guix refresh} reports an error.
4927 The following options are supported:
4931 @item --expression=@var{expr}
4932 @itemx -e @var{expr}
4933 Consider the package @var{expr} evaluates to.
4935 This is useful to precisely refer to a package, as in this example:
4938 guix refresh -l -e '(@@@@ (gnu packages commencement) glibc-final)'
4941 This command lists the dependents of the ``final'' libc (essentially all
4946 Update distribution source files (package recipes) in place. This is
4947 usually run from a checkout of the Guix source tree (@pxref{Running
4948 Guix Before It Is Installed}):
4951 $ ./pre-inst-env guix refresh -s non-core
4954 @xref{Defining Packages}, for more information on package definitions.
4956 @item --select=[@var{subset}]
4957 @itemx -s @var{subset}
4958 Select all the packages in @var{subset}, one of @code{core} or
4961 The @code{core} subset refers to all the packages at the core of the
4962 distribution---i.e., packages that are used to build ``everything
4963 else''. This includes GCC, libc, Binutils, Bash, etc. Usually,
4964 changing one of these packages in the distribution entails a rebuild of
4965 all the others. Thus, such updates are an inconvenience to users in
4966 terms of build time or bandwidth used to achieve the upgrade.
4968 The @code{non-core} subset refers to the remaining packages. It is
4969 typically useful in cases where an update of the core packages would be
4972 @item --type=@var{updater}
4973 @itemx -t @var{updater}
4974 Select only packages handled by @var{updater} (may be a comma-separated
4975 list of updaters). Currently, @var{updater} may be one of:
4979 the updater for GNU packages;
4981 the updater for GNOME packages;
4983 the updater for X.org packages;
4985 the updater for @uref{http://elpa.gnu.org/, ELPA} packages;
4987 the updater for @uref{http://cran.r-project.org/, CRAN} packages;
4989 the updater for @uref{http://www.bioconductor.org/, Bioconductor} R packages;
4991 the updater for @uref{https://pypi.python.org, PyPI} packages.
4993 the updater for @uref{https://rubygems.org, RubyGems} packages.
4995 the updater for @uref{https://github.com, GitHub} packages.
4997 the updater for @uref{https://hackage.haskell.org, Hackage} packages.
5000 For instance, the following command only checks for updates of Emacs
5001 packages hosted at @code{elpa.gnu.org} and for updates of CRAN packages:
5004 $ guix refresh --type=elpa,cran
5005 gnu/packages/statistics.scm:819:13: r-testthat would be upgraded from 0.10.0 to 0.11.0
5006 gnu/packages/emacs.scm:856:13: emacs-auctex would be upgraded from 11.88.6 to 11.88.9
5011 In addition, @command{guix refresh} can be passed one or more package
5012 names, as in this example:
5015 $ ./pre-inst-env guix refresh -u emacs idutils gcc-4.8.4
5019 The command above specifically updates the @code{emacs} and
5020 @code{idutils} packages. The @code{--select} option would have no
5021 effect in this case.
5023 When considering whether to upgrade a package, it is sometimes
5024 convenient to know which packages would be affected by the upgrade and
5025 should be checked for compatibility. For this the following option may
5026 be used when passing @command{guix refresh} one or more package names:
5030 @item --list-updaters
5032 List available updaters and exit (see @option{--type} above.)
5034 @item --list-dependent
5036 List top-level dependent packages that would need to be rebuilt as a
5037 result of upgrading one or more packages.
5041 Be aware that the @code{--list-dependent} option only
5042 @emph{approximates} the rebuilds that would be required as a result of
5043 an upgrade. More rebuilds might be required under some circumstances.
5046 $ guix refresh --list-dependent flex
5047 Building the following 120 packages would ensure 213 dependent packages are rebuilt:
5048 hop-2.4.0 geiser-0.4 notmuch-0.18 mu-0.9.9.5 cflow-1.4 idutils-4.6 @dots{}
5051 The command above lists a set of packages that could be built to check
5052 for compatibility with an upgraded @code{flex} package.
5054 The following options can be used to customize GnuPG operation:
5058 @item --gpg=@var{command}
5059 Use @var{command} as the GnuPG 2.x command. @var{command} is searched
5060 for in @code{$PATH}.
5062 @item --key-download=@var{policy}
5063 Handle missing OpenPGP keys according to @var{policy}, which may be one
5068 Always download missing OpenPGP keys from the key server, and add them
5069 to the user's GnuPG keyring.
5072 Never try to download missing OpenPGP keys. Instead just bail out.
5075 When a package signed with an unknown OpenPGP key is encountered, ask
5076 the user whether to download it or not. This is the default behavior.
5079 @item --key-server=@var{host}
5080 Use @var{host} as the OpenPGP key server when importing a public key.
5084 The @code{github} updater uses the
5085 @uref{https://developer.github.com/v3/, GitHub API} to query for new
5086 releases. When used repeatedly e.g. when refreshing all packages,
5087 GitHub will eventually refuse to answer any further API requests. By
5088 default 60 API requests per hour are allowed, and a full refresh on all
5089 GitHub packages in Guix requires more than this. Authentication with
5090 GitHub through the use of an API token alleviates these limits. To use
5091 an API token, set the environment variable @code{GUIX_GITHUB_TOKEN} to a
5092 token procured from @uref{https://github.com/settings/tokens} or
5096 @node Invoking guix lint
5097 @section Invoking @command{guix lint}
5098 The @command{guix lint} command is meant to help package developers avoid
5099 common errors and use a consistent style. It runs a number of checks on
5100 a given set of packages in order to find common mistakes in their
5101 definitions. Available @dfn{checkers} include (see
5102 @code{--list-checkers} for a complete list):
5107 Validate certain typographical and stylistic rules about package
5108 descriptions and synopses.
5110 @item inputs-should-be-native
5111 Identify inputs that should most likely be native inputs.
5115 @itemx source-file-name
5116 Probe @code{home-page} and @code{source} URLs and report those that are
5117 invalid. Check that the source file name is meaningful, e.g. is not
5118 just a version number or ``git-checkout'', without a declared
5119 @code{file-name} (@pxref{origin Reference}).
5122 @cindex security vulnerabilities
5123 @cindex CVE, Common Vulnerabilities and Exposures
5124 Report known vulnerabilities found in the Common Vulnerabilities and
5125 Exposures (CVE) databases of the current and past year
5126 @uref{https://nvd.nist.gov/download.cfm#CVE_FEED, published by the US
5129 To view information about a particular vulnerability, visit pages such as:
5133 @indicateurl{https://web.nvd.nist.gov/view/vuln/detail?vulnId=CVE-YYYY-ABCD}
5135 @indicateurl{https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-YYYY-ABCD}
5139 where @code{CVE-YYYY-ABCD} is the CVE identifier---e.g.,
5140 @code{CVE-2015-7554}.
5142 Package developers can specify in package recipes the
5143 @uref{https://nvd.nist.gov/cpe.cfm,Common Platform Enumeration (CPE)}
5144 name and version of the package when they differ from the name that Guix
5145 uses, as in this example:
5151 ;; CPE calls this package "grub2".
5152 (properties '((cpe-name . "grub2"))))
5156 Warn about obvious source code formatting issues: trailing white space,
5157 use of tabulations, etc.
5160 The general syntax is:
5163 guix lint @var{options} @var{package}@dots{}
5166 If no package is given on the command line, then all packages are checked.
5167 The @var{options} may be zero or more of the following:
5170 @item --list-checkers
5172 List and describe all the available checkers that will be run on packages
5177 Only enable the checkers specified in a comma-separated list using the
5178 names returned by @code{--list-checkers}.
5182 @node Invoking guix size
5183 @section Invoking @command{guix size}
5185 The @command{guix size} command helps package developers profile the
5186 disk usage of packages. It is easy to overlook the impact of an
5187 additional dependency added to a package, or the impact of using a
5188 single output for a package that could easily be split (@pxref{Packages
5189 with Multiple Outputs}). Such are the typical issues that
5190 @command{guix size} can highlight.
5192 The command can be passed a package specification such as @code{gcc-4.8}
5193 or @code{guile:debug}, or a file name in the store. Consider this
5197 $ guix size coreutils
5198 store item total self
5199 /gnu/store/@dots{}-coreutils-8.23 70.0 13.9 19.8%
5200 /gnu/store/@dots{}-gmp-6.0.0a 55.3 2.5 3.6%
5201 /gnu/store/@dots{}-acl-2.2.52 53.7 0.5 0.7%
5202 /gnu/store/@dots{}-attr-2.4.46 53.2 0.3 0.5%
5203 /gnu/store/@dots{}-gcc-4.8.4-lib 52.9 15.7 22.4%
5204 /gnu/store/@dots{}-glibc-2.21 37.2 37.2 53.1%
5208 The store items listed here constitute the @dfn{transitive closure} of
5209 Coreutils---i.e., Coreutils and all its dependencies, recursively---as
5210 would be returned by:
5213 $ guix gc -R /gnu/store/@dots{}-coreutils-8.23
5216 Here the output shows three columns next to store items. The first column,
5217 labeled ``total'', shows the size in mebibytes (MiB) of the closure of
5218 the store item---that is, its own size plus the size of all its
5219 dependencies. The next column, labeled ``self'', shows the size of the
5220 item itself. The last column shows the ratio of the size of the item
5221 itself to the space occupied by all the items listed here.
5223 In this example, we see that the closure of Coreutils weighs in at
5224 70@tie{}MiB, half of which is taken by libc. (That libc represents a
5225 large fraction of the closure is not a problem @i{per se} because it is
5226 always available on the system anyway.)
5228 When the package passed to @command{guix size} is available in the
5229 store, @command{guix size} queries the daemon to determine its
5230 dependencies, and measures its size in the store, similar to @command{du
5231 -ms --apparent-size} (@pxref{du invocation,,, coreutils, GNU
5234 When the given package is @emph{not} in the store, @command{guix size}
5235 reports information based on the available substitutes
5236 (@pxref{Substitutes}). This makes it possible it to profile disk usage of
5237 store items that are not even on disk, only available remotely.
5239 You can also specify several package names:
5242 $ guix size coreutils grep sed bash
5243 store item total self
5244 /gnu/store/@dots{}-coreutils-8.24 77.8 13.8 13.4%
5245 /gnu/store/@dots{}-grep-2.22 73.1 0.8 0.8%
5246 /gnu/store/@dots{}-bash-4.3.42 72.3 4.7 4.6%
5247 /gnu/store/@dots{}-readline-6.3 67.6 1.2 1.2%
5253 In this example we see that the combination of the four packages takes
5254 102.3@tie{}MiB in total, which is much less than the sum of each closure
5255 since they have a lot of dependencies in common.
5257 The available options are:
5261 @item --substitute-urls=@var{urls}
5262 Use substitute information from @var{urls}.
5263 @xref{client-substitute-urls, the same option for @code{guix build}}.
5265 @item --map-file=@var{file}
5266 Write a graphical map of disk usage in PNG format to @var{file}.
5268 For the example above, the map looks like this:
5270 @image{images/coreutils-size-map,5in,, map of Coreutils disk usage
5271 produced by @command{guix size}}
5273 This option requires that
5274 @uref{http://wingolog.org/software/guile-charting/, Guile-Charting} be
5275 installed and visible in Guile's module search path. When that is not
5276 the case, @command{guix size} fails as it tries to load it.
5278 @item --system=@var{system}
5279 @itemx -s @var{system}
5280 Consider packages for @var{system}---e.g., @code{x86_64-linux}.
5284 @node Invoking guix graph
5285 @section Invoking @command{guix graph}
5288 Packages and their dependencies form a @dfn{graph}, specifically a
5289 directed acyclic graph (DAG). It can quickly become difficult to have a
5290 mental model of the package DAG, so the @command{guix graph} command
5291 provides a visual representation of the DAG. @command{guix graph}
5292 emits a DAG representation in the input format of
5293 @uref{http://www.graphviz.org/, Graphviz}, so its output can be passed
5294 directly to the @command{dot} command of Graphviz. The general
5298 guix graph @var{options} @var{package}@dots{}
5301 For example, the following command generates a PDF file representing the
5302 package DAG for the GNU@tie{}Core Utilities, showing its build-time
5306 guix graph coreutils | dot -Tpdf > dag.pdf
5309 The output looks like this:
5311 @image{images/coreutils-graph,2in,,Dependency graph of the GNU Coreutils}
5313 Nice little graph, no?
5315 But there is more than one graph! The one above is concise: it is the
5316 graph of package objects, omitting implicit inputs such as GCC, libc,
5317 grep, etc. It is often useful to have such a concise graph, but
5318 sometimes one may want to see more details. @command{guix graph} supports
5319 several types of graphs, allowing you to choose the level of detail:
5323 This is the default type used in the example above. It shows the DAG of
5324 package objects, excluding implicit dependencies. It is concise, but
5325 filters out many details.
5328 This is the package DAG, @emph{including} implicit inputs.
5330 For instance, the following command:
5333 guix graph --type=bag-emerged coreutils | dot -Tpdf > dag.pdf
5336 ... yields this bigger graph:
5338 @image{images/coreutils-bag-graph,,5in,Detailed dependency graph of the GNU Coreutils}
5340 At the bottom of the graph, we see all the implicit inputs of
5341 @var{gnu-build-system} (@pxref{Build Systems, @code{gnu-build-system}}).
5343 Now, note that the dependencies of these implicit inputs---that is, the
5344 @dfn{bootstrap dependencies} (@pxref{Bootstrapping})---are not shown
5345 here, for conciseness.
5348 Similar to @code{bag-emerged}, but this time including all the bootstrap
5351 @item bag-with-origins
5352 Similar to @code{bag}, but also showing origins and their dependencies.
5355 This is the most detailed representation: It shows the DAG of
5356 derivations (@pxref{Derivations}) and plain store items. Compared to
5357 the above representation, many additional nodes are visible, including
5358 build scripts, patches, Guile modules, etc.
5360 For this type of graph, it is also possible to pass a @file{.drv} file
5361 name instead of a package name, as in:
5364 guix graph -t derivation `guix system build -d my-config.scm`
5368 All the types above correspond to @emph{build-time dependencies}. The
5369 following graph type represents the @emph{run-time dependencies}:
5373 This is the graph of @dfn{references} of a package output, as returned
5374 by @command{guix gc --references} (@pxref{Invoking guix gc}).
5376 If the given package output is not available in the store, @command{guix
5377 graph} attempts to obtain dependency information from substitutes.
5379 Here you can also pass a store file name instead of a package name. For
5380 example, the command below produces the reference graph of your profile
5381 (which can be big!):
5384 guix graph -t references `readlink -f ~/.guix-profile`
5388 The available options are the following:
5391 @item --type=@var{type}
5392 @itemx -t @var{type}
5393 Produce a graph output of @var{type}, where @var{type} must be one of
5394 the values listed above.
5397 List the supported graph types.
5399 @item --expression=@var{expr}
5400 @itemx -e @var{expr}
5401 Consider the package @var{expr} evaluates to.
5403 This is useful to precisely refer to a package, as in this example:
5406 guix graph -e '(@@@@ (gnu packages commencement) gnu-make-final)'
5411 @node Invoking guix environment
5412 @section Invoking @command{guix environment}
5414 @cindex reproducible build environments
5415 @cindex development environments
5416 The purpose of @command{guix environment} is to assist hackers in
5417 creating reproducible development environments without polluting their
5418 package profile. The @command{guix environment} tool takes one or more
5419 packages, builds all of their inputs, and creates a shell
5420 environment to use them.
5422 The general syntax is:
5425 guix environment @var{options} @var{package}@dots{}
5428 The following example spawns a new shell set up for the development of
5432 guix environment guile
5435 If the needed dependencies are not built yet, @command{guix environment}
5436 automatically builds them. The environment of the new shell is an augmented
5437 version of the environment that @command{guix environment} was run in.
5438 It contains the necessary search paths for building the given package
5439 added to the existing environment variables. To create a ``pure''
5440 environment, in which the original environment variables have been unset,
5441 use the @code{--pure} option@footnote{Users sometimes wrongfully augment
5442 environment variables such as @code{PATH} in their @file{~/.bashrc}
5443 file. As a consequence, when @code{guix environment} launches it, Bash
5444 may read @file{~/.bashrc}, thereby introducing ``impurities'' in these
5445 environment variables. It is an error to define such environment
5446 variables in @file{.bashrc}; instead, they should be defined in
5447 @file{.bash_profile}, which is sourced only by log-in shells.
5448 @xref{Bash Startup Files,,, bash, The GNU Bash Reference Manual}, for
5449 details on Bash start-up files.}.
5451 @vindex GUIX_ENVIRONMENT
5452 @command{guix environment} defines the @code{GUIX_ENVIRONMENT}
5453 variable in the shell it spawns. This allows users to, say, define a
5454 specific prompt for development environments in their @file{.bashrc}
5455 (@pxref{Bash Startup Files,,, bash, The GNU Bash Reference Manual}):
5458 if [ -n "$GUIX_ENVIRONMENT" ]
5460 export PS1="\u@@\h \w [dev]\$ "
5464 Additionally, more than one package may be specified, in which case the
5465 union of the inputs for the given packages are used. For example, the
5466 command below spawns a shell where all of the dependencies of both Guile
5467 and Emacs are available:
5470 guix environment guile emacs
5473 Sometimes an interactive shell session is not desired. An arbitrary
5474 command may be invoked by placing the @code{--} token to separate the
5475 command from the rest of the arguments:
5478 guix environment guile -- make -j4
5481 In other situations, it is more convenient to specify the list of
5482 packages needed in the environment. For example, the following command
5483 runs @command{python} from an environment containing Python@tie{}2.7 and
5487 guix environment --ad-hoc python2-numpy python-2.7 -- python
5490 Furthermore, one might want the dependencies of a package and also some
5491 additional packages that are not build-time or runtime dependencies, but
5492 are useful when developing nonetheless. Because of this, the
5493 @code{--ad-hoc} flag is positional. Packages appearing before
5494 @code{--ad-hoc} are interpreted as packages whose dependencies will be
5495 added to the environment. Packages appearing after are interpreted as
5496 packages that will be added to the environment directly. For example,
5497 the following command creates a Guix development environment that
5498 additionally includes Git and strace:
5501 guix environment guix --ad-hoc git strace
5504 Sometimes it is desirable to isolate the environment as much as
5505 possible, for maximal purity and reproducibility. In particular, when
5506 using Guix on a host distro that is not GuixSD, it is desirable to
5507 prevent access to @file{/usr/bin} and other system-wide resources from
5508 the development environment. For example, the following command spawns
5509 a Guile REPL in a ``container'' where only the store and the current
5510 working directory are mounted:
5513 guix environment --ad-hoc --container guile -- guile
5517 The @code{--container} option requires Linux-libre 3.19 or newer.
5520 The available options are summarized below.
5523 @item --expression=@var{expr}
5524 @itemx -e @var{expr}
5525 Create an environment for the package or list of packages that
5526 @var{expr} evaluates to.
5528 For example, running:
5531 guix environment -e '(@@ (gnu packages maths) petsc-openmpi)'
5534 starts a shell with the environment for this specific variant of the
5540 guix environment --ad-hoc -e '(@@ (gnu) %base-packages)'
5543 starts a shell with all the GuixSD base packages available.
5545 The above commands only the use default output of the given packages.
5546 To select other outputs, two element tuples can be specified:
5549 guix environment --ad-hoc -e '(list (@ (gnu packages bash) bash) "include")'
5552 @item --load=@var{file}
5553 @itemx -l @var{file}
5554 Create an environment for the package or list of packages that the code
5555 within @var{file} evaluates to.
5557 As an example, @var{file} might contain a definition like this
5558 (@pxref{Defining Packages}):
5561 @verbatiminclude environment-gdb.scm
5565 Include all specified packages in the resulting environment, as if an
5566 @i{ad hoc} package were defined with them as inputs. This option is
5567 useful for quickly creating an environment without having to write a
5568 package expression to contain the desired inputs.
5570 For instance, the command:
5573 guix environment --ad-hoc guile guile-sdl -- guile
5576 runs @command{guile} in an environment where Guile and Guile-SDL are
5579 Note that this example implicitly asks for the default output of
5580 @code{guile} and @code{guile-sdl}, but it is possible to ask for a
5581 specific output---e.g., @code{glib:bin} asks for the @code{bin} output
5582 of @code{glib} (@pxref{Packages with Multiple Outputs}).
5584 This option may be composed with the default behavior of @command{guix
5585 environment}. Packages appearing before @code{--ad-hoc} are interpreted
5586 as packages whose dependencies will be added to the environment, the
5587 default behavior. Packages appearing after are interpreted as packages
5588 that will be added to the environment directly.
5591 Unset existing environment variables when building the new environment.
5592 This has the effect of creating an environment in which search paths
5593 only contain package inputs.
5595 @item --search-paths
5596 Display the environment variable definitions that make up the
5599 @item --system=@var{system}
5600 @itemx -s @var{system}
5601 Attempt to build for @var{system}---e.g., @code{i686-linux}.
5606 Run @var{command} within an isolated container. The current working
5607 directory outside the container is mapped inside the container.
5608 Additionally, a dummy home directory is created that matches the current
5609 user's home directory, and @file{/etc/passwd} is configured accordingly.
5610 The spawned process runs as the current user outside the container, but
5611 has root privileges in the context of the container.
5615 For containers, share the network namespace with the host system.
5616 Containers created without this flag only have access to the loopback
5619 @item --expose=@var{source}[=@var{target}]
5620 For containers, expose the file system @var{source} from the host system
5621 as the read-only file system @var{target} within the container. If
5622 @var{target} is not specified, @var{source} is used as the target mount
5623 point in the container.
5625 The example below spawns a Guile REPL in a container in which the user's
5626 home directory is accessible read-only via the @file{/exchange}
5630 guix environment --container --expose=$HOME=/exchange guile -- guile
5633 @item --share=@var{source}[=@var{target}]
5634 For containers, share the file system @var{source} from the host system
5635 as the writable file system @var{target} within the container. If
5636 @var{target} is not specified, @var{source} is used as the target mount
5637 point in the container.
5639 The example below spawns a Guile REPL in a container in which the user's
5640 home directory is accessible for both reading and writing via the
5641 @file{/exchange} directory:
5644 guix environment --container --share=$HOME=/exchange guile -- guile
5648 It also supports all of the common build options that @command{guix
5649 build} supports (@pxref{Common Build Options}).
5651 @node Invoking guix publish
5652 @section Invoking @command{guix publish}
5654 The purpose of @command{guix publish} is to enable users to easily share
5655 their store with others, who can then use it as a substitute server
5656 (@pxref{Substitutes}).
5658 When @command{guix publish} runs, it spawns an HTTP server which allows
5659 anyone with network access to obtain substitutes from it. This means
5660 that any machine running Guix can also act as if it were a build farm,
5661 since the HTTP interface is compatible with Hydra, the software behind
5662 the @code{hydra.gnu.org} build farm.
5664 For security, each substitute is signed, allowing recipients to check
5665 their authenticity and integrity (@pxref{Substitutes}). Because
5666 @command{guix publish} uses the signing key of the system, which is only
5667 readable by the system administrator, it must be started as root; the
5668 @code{--user} option makes it drop root privileges early on.
5670 The signing key pair must be generated before @command{guix publish} is
5671 launched, using @command{guix archive --generate-key} (@pxref{Invoking
5674 The general syntax is:
5677 guix publish @var{options}@dots{}
5680 Running @command{guix publish} without any additional arguments will
5681 spawn an HTTP server on port 8080:
5687 Once a publishing server has been authorized (@pxref{Invoking guix
5688 archive}), the daemon may download substitutes from it:
5691 guix-daemon --substitute-urls=http://example.org:8080
5694 As a bonus, @command{guix publish} also serves as a content-addressed
5695 mirror for source files referenced in @code{origin} records
5696 (@pxref{origin Reference}). For instance, assuming @command{guix
5697 publish} is running on @code{example.org}, the following URL returns the
5698 raw @file{hello-2.10.tar.gz} file with the given SHA256 hash
5699 (represented in @code{nix-base32} format, @pxref{Invoking guix hash}):
5702 http://example.org/file/hello-2.10.tar.gz/sha256/0ssi1@dots{}ndq1i
5705 Obviously, these URLs only work for files that are in the store; in
5706 other cases, they return 404 (``Not Found'').
5708 The following options are available:
5711 @item --port=@var{port}
5712 @itemx -p @var{port}
5713 Listen for HTTP requests on @var{port}.
5715 @item --listen=@var{host}
5716 Listen on the network interface for @var{host}. The default is to
5717 accept connections from any interface.
5719 @item --user=@var{user}
5720 @itemx -u @var{user}
5721 Change privileges to @var{user} as soon as possible---i.e., once the
5722 server socket is open and the signing key has been read.
5724 @item --compression[=@var{level}]
5725 @itemx -C [@var{level}]
5726 Compress data using the given @var{level}. When @var{level} is zero,
5727 disable compression. The range 1 to 9 corresponds to different gzip
5728 compression levels: 1 is the fastest, and 9 is the best (CPU-intensive).
5731 Compression occurs on the fly and the compressed streams are not
5732 cached. Thus, to reduce load on the machine that runs @command{guix
5733 publish}, it may be a good idea to choose a low compression level, or to
5734 run @command{guix publish} behind a caching proxy.
5736 @item --ttl=@var{ttl}
5737 Produce @code{Cache-Control} HTTP headers that advertise a time-to-live
5738 (TTL) of @var{ttl}. @var{ttl} must denote a duration: @code{5d} means 5
5739 days, @code{1m} means 1 month, and so on.
5741 This allows the user's Guix to keep substitute information in cache for
5742 @var{ttl}. However, note that @code{guix publish} does not itself
5743 guarantee that the store items it provides will indeed remain available
5744 for as long as @var{ttl}.
5746 @item --repl[=@var{port}]
5747 @itemx -r [@var{port}]
5748 Spawn a Guile REPL server (@pxref{REPL Servers,,, guile, GNU Guile
5749 Reference Manual}) on @var{port} (37146 by default). This is used
5750 primarily for debugging a running @command{guix publish} server.
5753 Enabling @command{guix publish} on a GuixSD system is a one-liner: just
5754 add a call to @code{guix-publish-service} in the @code{services} field
5755 of the @code{operating-system} declaration (@pxref{guix-publish-service,
5756 @code{guix-publish-service}}).
5759 @node Invoking guix challenge
5760 @section Invoking @command{guix challenge}
5762 @cindex reproducible builds
5763 @cindex verifiable builds
5765 Do the binaries provided by this server really correspond to the source
5766 code it claims to build? Is a package build process deterministic?
5767 These are the questions the @command{guix challenge} command attempts to
5770 The former is obviously an important question: Before using a substitute
5771 server (@pxref{Substitutes}), one had better @emph{verify} that it
5772 provides the right binaries, and thus @emph{challenge} it. The latter
5773 is what enables the former: If package builds are deterministic, then
5774 independent builds of the package should yield the exact same result,
5775 bit for bit; if a server provides a binary different from the one
5776 obtained locally, it may be either corrupt or malicious.
5778 We know that the hash that shows up in @file{/gnu/store} file names is
5779 the hash of all the inputs of the process that built the file or
5780 directory---compilers, libraries, build scripts,
5781 etc. (@pxref{Introduction}). Assuming deterministic build processes,
5782 one store file name should map to exactly one build output.
5783 @command{guix challenge} checks whether there is, indeed, a single
5784 mapping by comparing the build outputs of several independent builds of
5785 any given store item.
5787 The command output looks like this:
5790 $ guix challenge --substitute-urls="https://hydra.gnu.org https://guix.example.org"
5791 updating list of substitutes from 'https://hydra.gnu.org'... 100.0%
5792 updating list of substitutes from 'https://guix.example.org'... 100.0%
5793 /gnu/store/@dots{}-openssl-1.0.2d contents differ:
5794 local hash: 0725l22r5jnzazaacncwsvp9kgf42266ayyp814v7djxs7nk963q
5795 https://hydra.gnu.org/nar/@dots{}-openssl-1.0.2d: 0725l22r5jnzazaacncwsvp9kgf42266ayyp814v7djxs7nk963q
5796 https://guix.example.org/nar/@dots{}-openssl-1.0.2d: 1zy4fmaaqcnjrzzajkdn3f5gmjk754b43qkq47llbyak9z0qjyim
5797 /gnu/store/@dots{}-git-2.5.0 contents differ:
5798 local hash: 00p3bmryhjxrhpn2gxs2fy0a15lnip05l97205pgbk5ra395hyha
5799 https://hydra.gnu.org/nar/@dots{}-git-2.5.0: 069nb85bv4d4a6slrwjdy8v1cn4cwspm3kdbmyb81d6zckj3nq9f
5800 https://guix.example.org/nar/@dots{}-git-2.5.0: 0mdqa9w1p6cmli6976v4wi0sw9r4p5prkj7lzfd1877wk11c9c73
5801 /gnu/store/@dots{}-pius-2.1.1 contents differ:
5802 local hash: 0k4v3m9z1zp8xzzizb7d8kjj72f9172xv078sq4wl73vnq9ig3ax
5803 https://hydra.gnu.org/nar/@dots{}-pius-2.1.1: 0k4v3m9z1zp8xzzizb7d8kjj72f9172xv078sq4wl73vnq9ig3ax
5804 https://guix.example.org/nar/@dots{}-pius-2.1.1: 1cy25x1a4fzq5rk0pmvc8xhwyffnqz95h2bpvqsz2mpvlbccy0gs
5808 In this example, @command{guix challenge} first scans the store to
5809 determine the set of locally-built derivations---as opposed to store
5810 items that were downloaded from a substitute server---and then queries
5811 all the substitute servers. It then reports those store items for which
5812 the servers obtained a result different from the local build.
5814 @cindex non-determinism, in package builds
5815 As an example, @code{guix.example.org} always gets a different answer.
5816 Conversely, @code{hydra.gnu.org} agrees with local builds, except in the
5817 case of Git. This might indicate that the build process of Git is
5818 non-deterministic, meaning that its output varies as a function of
5819 various things that Guix does not fully control, in spite of building
5820 packages in isolated environments (@pxref{Features}). Most common
5821 sources of non-determinism include the addition of timestamps in build
5822 results, the inclusion of random numbers, and directory listings sorted
5823 by inode number. See @uref{https://reproducible-builds.org/docs/}, for
5826 To find out what is wrong with this Git binary, we can do something along
5827 these lines (@pxref{Invoking guix archive}):
5830 $ wget -q -O - https://hydra.gnu.org/nar/@dots{}-git-2.5.0 \
5831 | guix archive -x /tmp/git
5832 $ diff -ur --no-dereference /gnu/store/@dots{}-git.2.5.0 /tmp/git
5835 This command shows the difference between the files resulting from the
5836 local build, and the files resulting from the build on
5837 @code{hydra.gnu.org} (@pxref{Overview, Comparing and Merging Files,,
5838 diffutils, Comparing and Merging Files}). The @command{diff} command
5839 works great for text files. When binary files differ, a better option
5840 is @uref{https://diffoscope.org/, Diffoscope}, a tool that helps
5841 visualize differences for all kinds of files.
5843 Once you have done that work, you can tell whether the differences are due
5844 to a non-deterministic build process or to a malicious server. We try
5845 hard to remove sources of non-determinism in packages to make it easier
5846 to verify substitutes, but of course, this is a process that
5847 involves not just Guix, but a large part of the free software community.
5848 In the meantime, @command{guix challenge} is one tool to help address
5851 If you are writing packages for Guix, you are encouraged to check
5852 whether @code{hydra.gnu.org} and other substitute servers obtain the
5853 same build result as you did with:
5856 $ guix challenge @var{package}
5860 where @var{package} is a package specification such as
5861 @code{guile@@2.0} or @code{glibc:debug}.
5863 The general syntax is:
5866 guix challenge @var{options} [@var{packages}@dots{}]
5869 When a difference is found between the hash of a locally-built item and
5870 that of a server-provided substitute, or among substitutes provided by
5871 different servers, the command displays it as in the example above and
5872 its exit code is 2 (other non-zero exit codes denote other kinds of
5875 The one option that matters is:
5879 @item --substitute-urls=@var{urls}
5880 Consider @var{urls} the whitespace-separated list of substitute source
5886 @node Invoking guix container
5887 @section Invoking @command{guix container}
5891 As of version @value{VERSION}, this tool is experimental. The interface
5892 is subject to radical change in the future.
5895 The purpose of @command{guix container} is to manipulate processes
5896 running within an isolated environment, commonly known as a
5897 ``container'', typically created by the @command{guix environment}
5898 (@pxref{Invoking guix environment}) and @command{guix system container}
5899 (@pxref{Invoking guix system}) commands.
5901 The general syntax is:
5904 guix container @var{action} @var{options}@dots{}
5907 @var{action} specifies the operation to perform with a container, and
5908 @var{options} specifies the context-specific arguments for the action.
5910 The following actions are available:
5914 Execute a command within the context of a running container.
5919 guix container exec @var{pid} @var{program} @var{arguments}@dots{}
5922 @var{pid} specifies the process ID of the running container.
5923 @var{program} specifies an executable file name within the root file
5924 system of the container. @var{arguments} are the additional options that
5925 will be passed to @var{program}.
5927 The following command launches an interactive login shell inside a
5928 GuixSD container, started by @command{guix system container}, and whose
5932 guix container exec 9001 /run/current-system/profile/bin/bash --login
5935 Note that the @var{pid} cannot be the parent process of a container. It
5936 must be PID 1 of the container or one of its child processes.
5940 @c *********************************************************************
5941 @node GNU Distribution
5942 @chapter GNU Distribution
5944 @cindex Guix System Distribution
5946 Guix comes with a distribution of the GNU system consisting entirely of
5947 free software@footnote{The term ``free'' here refers to the
5948 @url{http://www.gnu.org/philosophy/free-sw.html,freedom provided to
5949 users of that software}.}. The
5950 distribution can be installed on its own (@pxref{System Installation}),
5951 but it is also possible to install Guix as a package manager on top of
5952 an installed GNU/Linux system (@pxref{Installation}). To distinguish
5953 between the two, we refer to the standalone distribution as the Guix
5954 System Distribution, or GuixSD.
5956 The distribution provides core GNU packages such as GNU libc, GCC, and
5957 Binutils, as well as many GNU and non-GNU applications. The complete
5958 list of available packages can be browsed
5959 @url{http://www.gnu.org/software/guix/packages,on-line} or by
5960 running @command{guix package} (@pxref{Invoking guix package}):
5963 guix package --list-available
5966 Our goal is to provide a practical 100% free software distribution of
5967 Linux-based and other variants of GNU, with a focus on the promotion and
5968 tight integration of GNU components, and an emphasis on programs and
5969 tools that help users exert that freedom.
5971 Packages are currently available on the following platforms:
5976 Intel/AMD @code{x86_64} architecture, Linux-Libre kernel;
5979 Intel 32-bit architecture (IA32), Linux-Libre kernel;
5982 ARMv7-A architecture with hard float, Thumb-2 and NEON,
5983 using the EABI hard-float application binary interface (ABI),
5984 and Linux-Libre kernel.
5986 @item mips64el-linux
5987 little-endian 64-bit MIPS processors, specifically the Loongson series,
5988 n32 ABI, and Linux-Libre kernel.
5992 GuixSD itself is currently only available on @code{i686} and @code{x86_64}.
5995 For information on porting to other architectures or kernels,
5999 * System Installation:: Installing the whole operating system.
6000 * System Configuration:: Configuring the operating system.
6001 * Installing Debugging Files:: Feeding the debugger.
6002 * Security Updates:: Deploying security fixes quickly.
6003 * Package Modules:: Packages from the programmer's viewpoint.
6004 * Packaging Guidelines:: Growing the distribution.
6005 * Bootstrapping:: GNU/Linux built from scratch.
6006 * Porting:: Targeting another platform or kernel.
6009 Building this distribution is a cooperative effort, and you are invited
6010 to join! @xref{Contributing}, for information about how you can help.
6012 @node System Installation
6013 @section System Installation
6015 @cindex Guix System Distribution
6016 This section explains how to install the Guix System Distribution
6017 on a machine. The Guix package manager can
6018 also be installed on top of a running GNU/Linux system,
6019 @pxref{Installation}.
6023 @c This paragraph is for people reading this from tty2 of the
6024 @c installation image.
6025 You are reading this documentation with an Info reader. For details on
6026 how to use it, hit the @key{RET} key (``return'' or ``enter'') on the
6027 link that follows: @pxref{Top, Info reader,, info-stnd, Stand-alone GNU
6028 Info}. Hit @kbd{l} afterwards to come back here.
6030 Alternately, run @command{info info} in another tty to keep the manual
6036 * Limitations:: What you can expect.
6037 * Hardware Considerations:: Supported hardware.
6038 * USB Stick Installation:: Preparing the installation medium.
6039 * Preparing for Installation:: Networking, partitioning, etc.
6040 * Proceeding with the Installation:: The real thing.
6041 * Building the Installation Image:: How this comes to be.
6045 @subsection Limitations
6047 As of version @value{VERSION}, the Guix System Distribution (GuixSD) is
6048 not production-ready. It may contain bugs and lack important
6049 features. Thus, if you are looking for a stable production system that
6050 respects your freedom as a computer user, a good solution at this point
6051 is to consider @url{http://www.gnu.org/distros/free-distros.html, one of
6052 the more established GNU/Linux distributions}. We hope you can soon switch
6053 to the GuixSD without fear, of course. In the meantime, you can
6054 also keep using your distribution and try out the package manager on top
6055 of it (@pxref{Installation}).
6057 Before you proceed with the installation, be aware of the following
6058 noteworthy limitations applicable to version @value{VERSION}:
6062 The installation process does not include a graphical user interface and
6063 requires familiarity with GNU/Linux (see the following subsections to
6064 get a feel of what that means.)
6067 Support for the Logical Volume Manager (LVM) is missing.
6070 Few system services are currently supported out-of-the-box
6074 More than 3,200 packages are available, but you may
6075 occasionally find that a useful package is missing.
6078 GNOME, Xfce, and Enlightenment are available (@pxref{Desktop Services}),
6079 as well as a number of X11 window managers. However, some graphical
6080 applications may be missing, as well as KDE.
6083 You have been warned! But more than a disclaimer, this is an invitation
6084 to report issues (and success stories!), and to join us in improving it.
6085 @xref{Contributing}, for more info.
6088 @node Hardware Considerations
6089 @subsection Hardware Considerations
6091 @cindex hardware support on GuixSD
6092 GNU@tie{}GuixSD focuses on respecting the user's computing freedom. It
6093 builds around the kernel Linux-libre, which means that only hardware for
6094 which free software drivers and firmware exist is supported. Nowadays,
6095 a wide range of off-the-shelf hardware is supported on
6096 GNU/Linux-libre---from keyboards to graphics cards to scanners and
6097 Ethernet controllers. Unfortunately, there are still areas where
6098 hardware vendors deny users control over their own computing, and such
6099 hardware is not supported on GuixSD.
6101 @cindex WiFi, hardware support
6102 One of the main areas where free drivers or firmware are lacking is WiFi
6103 devices. WiFi devices known to work include those using Atheros chips
6104 (AR9271 and AR7010), which corresponds to the @code{ath9k} Linux-libre
6105 driver, and for which free firmware exists and is available
6106 out-of-the-box on GuixSD, as part of @var{%base-firmware}
6107 (@pxref{operating-system Reference, @code{firmware}}).
6109 @cindex RYF, Respects Your Freedom
6110 The @uref{https://www.fsf.org/, Free Software Foundation} runs
6111 @uref{https://www.fsf.org/ryf, @dfn{Respects Your Freedom}} (RYF), a
6112 certification program for hardware products that respect your freedom
6113 and your privacy and ensure that you have control over your device. We
6114 encourage you to check the list of RYF-certified devices.
6116 Another useful resource is the @uref{https://www.h-node.org/, H-Node}
6117 web site. It contains a catalog of hardware devices with information
6118 about their support in GNU/Linux.
6121 @node USB Stick Installation
6122 @subsection USB Stick Installation
6124 An installation image for USB sticks can be downloaded from
6125 @indicateurl{ftp://alpha.gnu.org/gnu/guix/guixsd-usb-install-@value{VERSION}.@var{system}.xz},
6126 where @var{system} is one of:
6130 for a GNU/Linux system on Intel/AMD-compatible 64-bit CPUs;
6133 for a 32-bit GNU/Linux system on Intel-compatible CPUs.
6136 This image contains a single partition with the tools necessary for an
6137 installation. It is meant to be copied @emph{as is} to a large-enough
6140 To copy the image to a USB stick, follow these steps:
6144 Decompress the image using the @command{xz} command:
6147 xz -d guixsd-usb-install-@value{VERSION}.@var{system}.xz
6151 Insert a USB stick of 1@tie{}GiB or more into your machine, and determine
6152 its device name. Assuming that the USB stick is known as @file{/dev/sdX},
6153 copy the image with:
6156 dd if=guixsd-usb-install-@value{VERSION}.x86_64 of=/dev/sdX
6159 Access to @file{/dev/sdX} usually requires root privileges.
6162 Once this is done, you should be able to reboot the system and boot from
6163 the USB stick. The latter usually requires you to get in the BIOS' boot
6164 menu, where you can choose to boot from the USB stick.
6166 @node Preparing for Installation
6167 @subsection Preparing for Installation
6169 Once you have successfully booted the image on the USB stick, you should
6170 end up with a root prompt. Several console TTYs are configured and can
6171 be used to run commands as root. TTY2 shows this documentation,
6172 browsable using the Info reader commands (@pxref{Top,,, info-stnd,
6173 Stand-alone GNU Info}). The installation system runs the GPM mouse
6174 daemon, which allows you to select text with the left mouse button and
6175 to paste it with the middle button.
6178 Installation requires access to the Internet so that any missing
6179 dependencies of your system configuration can be downloaded. See the
6180 ``Networking'' section below.
6183 The installation system includes many common tools needed for this task.
6184 But it is also a full-blown GuixSD system, which means that you can
6185 install additional packages, should you need it, using @command{guix
6186 package} (@pxref{Invoking guix package}).
6188 @subsubsection Keyboard Layout
6190 @cindex keyboard layout
6191 The installation image uses the US qwerty keyboard layout. If you want
6192 to change it, you can use the @command{loadkeys} command. For example,
6193 the following command selects the Dvorak keyboard layout:
6199 See the files under @file{/run/current-system/profile/share/keymaps} for
6200 a list of available keyboard layouts. Run @command{man loadkeys} for
6203 @subsubsection Networking
6205 Run the following command see what your network interfaces are called:
6212 @dots{} or, using the GNU/Linux-specific @command{ip} command:
6218 @c http://cgit.freedesktop.org/systemd/systemd/tree/src/udev/udev-builtin-net_id.c#n20
6219 Wired interfaces have a name starting with @samp{e}; for example, the
6220 interface corresponding to the first on-board Ethernet controller is
6221 called @samp{eno1}. Wireless interfaces have a name starting with
6222 @samp{w}, like @samp{w1p2s0}.
6225 @item Wired connection
6226 To configure a wired network run the following command, substituting
6227 @var{interface} with the name of the wired interface you want to use.
6230 ifconfig @var{interface} up
6233 @item Wireless connection
6234 To configure wireless networking, you can create a configuration file
6235 for the @command{wpa_supplicant} configuration tool (its location is not
6236 important) using one of the available text editors such as
6240 zile wpa_supplicant.conf
6243 As an example, the following stanza can go to this file and will work
6244 for many wireless networks, provided you give the actual SSID and
6245 passphrase for the network you are connecting to:
6249 ssid="@var{my-ssid}"
6251 psk="the network's secret passphrase"
6255 Start the wireless service and run it in the background with the
6256 following command (substitute @var{interface} with the name of the
6257 network interface you want to use):
6260 wpa_supplicant -c wpa_supplicant.conf -i @var{interface} -B
6263 Run @command{man wpa_supplicant} for more information.
6266 At this point, you need to acquire an IP address. On a network where IP
6267 addresses are automatically assigned @i{via} DHCP, you can run:
6270 dhclient -v @var{interface}
6273 Try to ping a server to see if networking is up and running:
6279 Setting up network access is almost always a requirement because the
6280 image does not contain all the software and tools that may be needed.
6282 @subsubsection Disk Partitioning
6284 Unless this has already been done, the next step is to partition, and
6285 then format the target partition(s).
6287 The installation image includes several partitioning tools, including
6288 Parted (@pxref{Overview,,, parted, GNU Parted User Manual}),
6289 @command{fdisk}, and @command{cfdisk}. Run it and set up your disk with
6290 the partition layout you want:
6296 Once you are done partitioning the target hard disk drive, you have to
6297 create a file system on the relevant partition(s)@footnote{Currently
6298 GuixSD pretty much assumes an ext4 file system. In particular, code
6299 that reads partition UUIDs and labels only works with ext4. This will
6300 be fixed in the future.}.
6302 Preferably, assign partitions a label so that you can easily and
6303 reliably refer to them in @code{file-system} declarations (@pxref{File
6304 Systems}). This is typically done using the @code{-L} option of
6305 @command{mkfs.ext4} and related commands. So, assuming the target root
6306 partition lives at @file{/dev/sda1}, a file system with the label
6307 @code{my-root} can be created with:
6310 mkfs.ext4 -L my-root /dev/sda1
6313 @c FIXME: Uncomment this once GRUB fully supports encrypted roots.
6314 @c A typical command sequence may be:
6318 @c @dots{} Create partitions etc.@dots{}
6319 @c # cryptsetup luksFormat /dev/sdX1
6320 @c # cryptsetup open --type luks /dev/sdX1 my-partition
6321 @c # mkfs.ext4 -L my-root /dev/mapper/my-partition
6324 In addition to e2fsprogs, the suite of tools to manipulate
6325 ext2/ext3/ext4 file systems, the installation image includes
6326 Cryptsetup/LUKS for disk encryption.
6328 Once that is done, mount the target root partition under @file{/mnt}
6329 with a command like (again, assuming @file{/dev/sda1} is the root
6333 mount /dev/sda1 /mnt
6336 Finally, if you plan to use one or more swap partitions (@pxref{Memory
6337 Concepts, swap space,, libc, The GNU C Library Reference Manual}), make
6338 sure to initialize them with @command{mkswap}. Assuming you have one
6339 swap partition on @file{/dev/sda2}, you would run:
6345 @node Proceeding with the Installation
6346 @subsection Proceeding with the Installation
6348 With the target partitions ready and the target root mounted on
6349 @file{/mnt}, we're ready to go. First, run:
6352 herd start cow-store /mnt
6355 This makes @file{/gnu/store} copy-on-write, such that packages added to it
6356 during the installation phase are written to the target disk on @file{/mnt}
6357 rather than kept in memory. This is necessary because the first phase of
6358 the @command{guix system init} command (see below) entails downloads or
6359 builds to @file{/gnu/store} which, initially, is an in-memory file system.
6361 Next, you have to edit a file and
6362 provide the declaration of the operating system to be installed. To
6363 that end, the installation system comes with two text editors: GNU nano
6364 (@pxref{Top,,, nano, GNU nano Manual}), and GNU Zile, an Emacs clone.
6365 We strongly recommend storing that file on the target root file system, say,
6366 as @file{/mnt/etc/config.scm}. Failing to do that, you will have lost your
6367 configuration file once you have rebooted into the newly-installed system.
6369 @xref{Using the Configuration System}, for an overview of the
6370 configuration file. The example configurations discussed in that
6371 section are available under @file{/etc/configuration} in the
6372 installation image. Thus, to get started with a system configuration
6373 providing a graphical display server (a ``desktop'' system), you can run
6374 something along these lines:
6378 # cp /etc/configuration/desktop.scm /mnt/etc/config.scm
6379 # zile /mnt/etc/config.scm
6382 You should pay attention to what your configuration file contains, and
6387 Make sure the @code{grub-configuration} form refers to the device you
6388 want to install GRUB on.
6391 Be sure that your partition labels match the value of their respective
6392 @code{device} fields in your @code{file-system} configuration, assuming
6393 your @code{file-system} configuration sets the value of @code{title} to
6397 Once you are done preparing the configuration file, the new system must
6398 be initialized (remember that the target root file system is mounted
6402 guix system init /mnt/etc/config.scm /mnt
6406 This copies all the necessary files and installs GRUB on
6407 @file{/dev/sdX}, unless you pass the @option{--no-grub} option. For
6408 more information, @pxref{Invoking guix system}. This command may trigger
6409 downloads or builds of missing packages, which can take some time.
6411 Once that command has completed---and hopefully succeeded!---you can run
6412 @command{reboot} and boot into the new system. The @code{root} password
6413 in the new system is initially empty; other users' passwords need to be
6414 initialized by running the @command{passwd} command as @code{root},
6415 unless your configuration specifies otherwise
6416 (@pxref{user-account-password, user account passwords}).
6418 Join us on @code{#guix} on the Freenode IRC network or on
6419 @file{guix-devel@@gnu.org} to share your experience---good or not so
6422 @node Building the Installation Image
6423 @subsection Building the Installation Image
6425 The installation image described above was built using the @command{guix
6426 system} command, specifically:
6428 @c FIXME: 1G is too much; see <http://bugs.gnu.org/23077>.
6430 guix system disk-image --image-size=1G gnu/system/install.scm
6433 Have a look at @file{gnu/system/install.scm} in the source tree,
6434 and see also @ref{Invoking guix system} for more information
6435 about the installation image.
6437 @node System Configuration
6438 @section System Configuration
6440 @cindex system configuration
6441 The Guix System Distribution supports a consistent whole-system configuration
6442 mechanism. By that we mean that all aspects of the global system
6443 configuration---such as the available system services, timezone and
6444 locale settings, user accounts---are declared in a single place. Such
6445 a @dfn{system configuration} can be @dfn{instantiated}---i.e., effected.
6447 One of the advantages of putting all the system configuration under the
6448 control of Guix is that it supports transactional system upgrades, and
6449 makes it possible to roll back to a previous system instantiation,
6450 should something go wrong with the new one (@pxref{Features}). Another
6451 advantage is that it makes it easy to replicate the exact same configuration
6452 across different machines, or at different points in time, without
6453 having to resort to additional administration tools layered on top of
6454 the own tools of the system.
6455 @c Yes, we're talking of Puppet, Chef, & co. here. ↑
6457 This section describes this mechanism. First we focus on the system
6458 administrator's viewpoint---explaining how the system is configured and
6459 instantiated. Then we show how this mechanism can be extended, for
6460 instance to support new system services.
6463 * Using the Configuration System:: Customizing your GNU system.
6464 * operating-system Reference:: Detail of operating-system declarations.
6465 * File Systems:: Configuring file system mounts.
6466 * Mapped Devices:: Block device extra processing.
6467 * User Accounts:: Specifying user accounts.
6468 * Locales:: Language and cultural convention settings.
6469 * Services:: Specifying system services.
6470 * Setuid Programs:: Programs running with root privileges.
6471 * X.509 Certificates:: Authenticating HTTPS servers.
6472 * Name Service Switch:: Configuring libc's name service switch.
6473 * Initial RAM Disk:: Linux-Libre bootstrapping.
6474 * GRUB Configuration:: Configuring the boot loader.
6475 * Invoking guix system:: Instantiating a system configuration.
6476 * Running GuixSD in a VM:: How to run GuixSD in a virtual machine.
6477 * Defining Services:: Adding new service definitions.
6480 @node Using the Configuration System
6481 @subsection Using the Configuration System
6483 The operating system is configured by providing an
6484 @code{operating-system} declaration in a file that can then be passed to
6485 the @command{guix system} command (@pxref{Invoking guix system}). A
6486 simple setup, with the default system services, the default Linux-Libre
6487 kernel, initial RAM disk, and boot loader looks like this:
6489 @findex operating-system
6491 @include os-config-bare-bones.texi
6494 This example should be self-describing. Some of the fields defined
6495 above, such as @code{host-name} and @code{bootloader}, are mandatory.
6496 Others, such as @code{packages} and @code{services}, can be omitted, in
6497 which case they get a default value.
6499 Below we discuss the effect of some of the most important fields
6500 (@pxref{operating-system Reference}, for details about all the available
6501 fields), and how to @dfn{instantiate} the operating system using
6502 @command{guix system}.
6504 @unnumberedsubsubsec Globally-Visible Packages
6506 @vindex %base-packages
6507 The @code{packages} field lists packages that will be globally visible
6508 on the system, for all user accounts---i.e., in every user's @code{PATH}
6509 environment variable---in addition to the per-user profiles
6510 (@pxref{Invoking guix package}). The @var{%base-packages} variable
6511 provides all the tools one would expect for basic user and administrator
6512 tasks---including the GNU Core Utilities, the GNU Networking Utilities,
6513 the GNU Zile lightweight text editor, @command{find}, @command{grep},
6514 etc. The example above adds tcpdump to those, taken from the @code{(gnu
6515 packages admin)} module (@pxref{Package Modules}).
6517 @findex specification->package
6518 Referring to packages by variable name, like @var{tcpdump} above, has
6519 the advantage of being unambiguous; it also allows typos and such to be
6520 diagnosed right away as ``unbound variables''. The downside is that one
6521 needs to know which module defines which package, and to augment the
6522 @code{use-package-modules} line accordingly. To avoid that, one can use
6523 the @code{specification->package} procedure of the @code{(gnu packages)}
6524 module, which returns the best package for a given name or name and
6528 (use-modules (gnu packages))
6532 (packages (append (map specification->package
6533 '("tcpdump" "htop" "gnupg@@2.0"))
6537 @unnumberedsubsubsec System Services
6539 @vindex %base-services
6540 The @code{services} field lists @dfn{system services} to be made
6541 available when the system starts (@pxref{Services}).
6542 The @code{operating-system} declaration above specifies that, in
6543 addition to the basic services, we want the @command{lshd} secure shell
6544 daemon listening on port 2222 (@pxref{Networking Services,
6545 @code{lsh-service}}). Under the hood,
6546 @code{lsh-service} arranges so that @code{lshd} is started with the
6547 right command-line options, possibly with supporting configuration files
6548 generated as needed (@pxref{Defining Services}).
6550 @cindex customization, of services
6551 @findex modify-services
6552 Occasionally, instead of using the base services as is, you will want to
6553 customize them. To do this, use @code{modify-services} (@pxref{Service
6554 Reference, @code{modify-services}}) to modify the list.
6556 For example, suppose you want to modify @code{guix-daemon} and Mingetty
6557 (the console log-in) in the @var{%base-services} list (@pxref{Base
6558 Services, @code{%base-services}}). To do that, you can write the
6559 following in your operating system declaration:
6562 (define %my-services
6563 ;; My very own list of services.
6564 (modify-services %base-services
6565 (guix-service-type config =>
6568 (use-substitutes? #f)
6569 (extra-options '("--gc-keep-derivations"))))
6570 (mingetty-service-type config =>
6571 (mingetty-configuration
6573 (motd (plain-file "motd" "Howdy!"))))))
6577 (services %my-services))
6580 This changes the configuration---i.e., the service parameters---of the
6581 @code{guix-service-type} instance, and that of all the
6582 @code{mingetty-service-type} instances in the @var{%base-services} list.
6583 Observe how this is accomplished: first, we arrange for the original
6584 configuration to be bound to the identifier @code{config} in the
6585 @var{body}, and then we write the @var{body} so that it evaluates to the
6586 desired configuration. In particular, notice how we use @code{inherit}
6587 to create a new configuration which has the same values as the old
6588 configuration, but with a few modifications.
6590 The configuration for a typical ``desktop'' usage, with the X11 display
6591 server, GNOME and Xfce (users can choose which of these desktop
6592 environments to use at the log-in screen by pressing @kbd{F1}), network
6593 management, power management, and more, would look like this:
6596 @include os-config-desktop.texi
6599 A graphical environment with a choice of lightweight window managers
6600 instead of full-blown desktop environments would look like this:
6603 @include os-config-lightweight-desktop.texi
6606 @xref{Desktop Services}, for the exact list of services provided by
6607 @var{%desktop-services}. @xref{X.509 Certificates}, for background
6608 information about the @code{nss-certs} package that is used here.
6610 Again, @var{%desktop-services} is just a list of service objects. If
6611 you want to remove services from there, you can do so using the
6612 procedures for list filtering (@pxref{SRFI-1 Filtering and
6613 Partitioning,,, guile, GNU Guile Reference Manual}). For instance, the
6614 following expression returns a list that contains all the services in
6615 @var{%desktop-services} minus the Avahi service:
6618 (remove (lambda (service)
6619 (eq? (service-kind service) avahi-service-type))
6623 @unnumberedsubsubsec Instantiating the System
6625 Assuming the @code{operating-system} declaration
6626 is stored in the @file{my-system-config.scm}
6627 file, the @command{guix system reconfigure my-system-config.scm} command
6628 instantiates that configuration, and makes it the default GRUB boot
6629 entry (@pxref{Invoking guix system}).
6631 The normal way to change the system configuration is by updating this
6632 file and re-running @command{guix system reconfigure}. One should never
6633 have to touch files in @command{/etc} or to run commands that modify the
6634 system state such as @command{useradd} or @command{grub-install}. In
6635 fact, you must avoid that since that would not only void your warranty
6636 but also prevent you from rolling back to previous versions of your
6637 system, should you ever need to.
6639 @cindex roll-back, of the operating system
6640 Speaking of roll-back, each time you run @command{guix system
6641 reconfigure}, a new @dfn{generation} of the system is created---without
6642 modifying or deleting previous generations. Old system generations get
6643 an entry in the GRUB boot menu, allowing you to boot them in case
6644 something went wrong with the latest generation. Reassuring, no? The
6645 @command{guix system list-generations} command lists the system
6646 generations available on disk.
6648 @unnumberedsubsubsec The Programming Interface
6650 At the Scheme level, the bulk of an @code{operating-system} declaration
6651 is instantiated with the following monadic procedure (@pxref{The Store
6654 @deffn {Monadic Procedure} operating-system-derivation os
6655 Return a derivation that builds @var{os}, an @code{operating-system}
6656 object (@pxref{Derivations}).
6658 The output of the derivation is a single directory that refers to all
6659 the packages, configuration files, and other supporting files needed to
6660 instantiate @var{os}.
6663 This procedure is provided by the @code{(gnu system)} module. Along
6664 with @code{(gnu services)} (@pxref{Services}), this module contains the
6665 guts of GuixSD. Make sure to visit it!
6668 @node operating-system Reference
6669 @subsection @code{operating-system} Reference
6671 This section summarizes all the options available in
6672 @code{operating-system} declarations (@pxref{Using the Configuration
6675 @deftp {Data Type} operating-system
6676 This is the data type representing an operating system configuration.
6677 By that, we mean all the global system configuration, not per-user
6678 configuration (@pxref{Using the Configuration System}).
6681 @item @code{kernel} (default: @var{linux-libre})
6682 The package object of the operating system kernel to use@footnote{Currently
6683 only the Linux-libre kernel is supported. In the future, it will be
6684 possible to use the GNU@tie{}Hurd.}.
6686 @item @code{kernel-arguments} (default: @code{'()})
6687 List of strings or gexps representing additional arguments to pass on
6688 the command-line of the kernel---e.g., @code{("console=ttyS0")}.
6690 @item @code{bootloader}
6691 The system bootloader configuration object. @xref{GRUB Configuration}.
6693 @item @code{initrd} (default: @code{base-initrd})
6694 A two-argument monadic procedure that returns an initial RAM disk for
6695 the Linux kernel. @xref{Initial RAM Disk}.
6697 @item @code{firmware} (default: @var{%base-firmware})
6699 List of firmware packages loadable by the operating system kernel.
6701 The default includes firmware needed for Atheros-based WiFi devices
6702 (Linux-libre module @code{ath9k}). @xref{Hardware Considerations}, for
6703 more info on supported hardware.
6705 @item @code{host-name}
6708 @item @code{hosts-file}
6710 A file-like object (@pxref{G-Expressions, file-like objects}) for use as
6711 @file{/etc/hosts} (@pxref{Host Names,,, libc, The GNU C Library
6712 Reference Manual}). The default is a file with entries for
6713 @code{localhost} and @var{host-name}.
6715 @item @code{mapped-devices} (default: @code{'()})
6716 A list of mapped devices. @xref{Mapped Devices}.
6718 @item @code{file-systems}
6719 A list of file systems. @xref{File Systems}.
6721 @item @code{swap-devices} (default: @code{'()})
6722 @cindex swap devices
6723 A list of strings identifying devices to be used for ``swap space''
6724 (@pxref{Memory Concepts,,, libc, The GNU C Library Reference Manual}).
6725 For example, @code{'("/dev/sda3")}.
6727 @item @code{users} (default: @code{%base-user-accounts})
6728 @itemx @code{groups} (default: @var{%base-groups})
6729 List of user accounts and groups. @xref{User Accounts}.
6731 @item @code{skeletons} (default: @code{(default-skeletons)})
6732 A list target file name/file-like object tuples (@pxref{G-Expressions,
6733 file-like objects}). These are the skeleton files that will be added to
6734 the home directory of newly-created user accounts.
6736 For instance, a valid value may look like this:
6739 `((".bashrc" ,(plain-file "bashrc" "echo Hello\n"))
6740 (".guile" ,(plain-file "guile"
6741 "(use-modules (ice-9 readline))
6742 (activate-readline)")))
6745 @item @code{issue} (default: @var{%default-issue})
6746 A string denoting the contents of the @file{/etc/issue} file, which is
6747 displayed when users log in on a text console.
6749 @item @code{packages} (default: @var{%base-packages})
6750 The set of packages installed in the global profile, which is accessible
6751 at @file{/run/current-system/profile}.
6753 The default set includes core utilities and it is good practice to
6754 install non-core utilities in user profiles (@pxref{Invoking guix
6757 @item @code{timezone}
6758 A timezone identifying string---e.g., @code{"Europe/Paris"}.
6760 You can run the @command{tzselect} command to find out which timezone
6761 string corresponds to your region. Choosing an invalid timezone name
6762 causes @command{guix system} to fail.
6764 @item @code{locale} (default: @code{"en_US.utf8"})
6765 The name of the default locale (@pxref{Locale Names,,, libc, The GNU C
6766 Library Reference Manual}). @xref{Locales}, for more information.
6768 @item @code{locale-definitions} (default: @var{%default-locale-definitions})
6769 The list of locale definitions to be compiled and that may be used at
6770 run time. @xref{Locales}.
6772 @item @code{locale-libcs} (default: @code{(list @var{glibc})})
6773 The list of GNU@tie{}libc packages whose locale data and tools are used
6774 to build the locale definitions. @xref{Locales}, for compatibility
6775 considerations that justify this option.
6777 @item @code{name-service-switch} (default: @var{%default-nss})
6778 Configuration of the libc name service switch (NSS)---a
6779 @code{<name-service-switch>} object. @xref{Name Service Switch}, for
6782 @item @code{services} (default: @var{%base-services})
6783 A list of service objects denoting system services. @xref{Services}.
6785 @item @code{pam-services} (default: @code{(base-pam-services)})
6787 @cindex pluggable authentication modules
6788 Linux @dfn{pluggable authentication module} (PAM) services.
6789 @c FIXME: Add xref to PAM services section.
6791 @item @code{setuid-programs} (default: @var{%setuid-programs})
6792 List of string-valued G-expressions denoting setuid programs.
6793 @xref{Setuid Programs}.
6795 @item @code{sudoers-file} (default: @var{%sudoers-specification})
6796 @cindex sudoers file
6797 The contents of the @file{/etc/sudoers} file as a file-like object
6798 (@pxref{G-Expressions, @code{local-file} and @code{plain-file}}).
6800 This file specifies which users can use the @command{sudo} command, what
6801 they are allowed to do, and what privileges they may gain. The default
6802 is that only @code{root} and members of the @code{wheel} group may use
6809 @subsection File Systems
6811 The list of file systems to be mounted is specified in the
6812 @code{file-systems} field of the operating system declaration
6813 (@pxref{Using the Configuration System}). Each file system is declared
6814 using the @code{file-system} form, like this:
6818 (mount-point "/home")
6819 (device "/dev/sda3")
6823 As usual, some of the fields are mandatory---those shown in the example
6824 above---while others can be omitted. These are described below.
6826 @deftp {Data Type} file-system
6827 Objects of this type represent file systems to be mounted. They
6828 contain the following members:
6832 This is a string specifying the type of the file system---e.g.,
6835 @item @code{mount-point}
6836 This designates the place where the file system is to be mounted.
6839 This names the ``source'' of the file system. By default it is the name
6840 of a node under @file{/dev}, but its meaning depends on the @code{title}
6841 field described below.
6843 @item @code{title} (default: @code{'device})
6844 This is a symbol that specifies how the @code{device} field is to be
6847 When it is the symbol @code{device}, then the @code{device} field is
6848 interpreted as a file name; when it is @code{label}, then @code{device}
6849 is interpreted as a partition label name; when it is @code{uuid},
6850 @code{device} is interpreted as a partition unique identifier (UUID).
6852 UUIDs may be converted from their string representation (as shown by the
6853 @command{tune2fs -l} command) using the @code{uuid} form@footnote{The
6854 @code{uuid} form expects 16-byte UUIDs as defined in
6855 @uref{https://tools.ietf.org/html/rfc4122, RFC@tie{}4122}. This is the
6856 form of UUID used by the ext2 family of file systems and others, but it
6857 is different from ``UUIDs'' found in FAT file systems, for instance.},
6862 (mount-point "/home")
6865 (device (uuid "4dab5feb-d176-45de-b287-9b0a6e4c01cb")))
6868 The @code{label} and @code{uuid} options offer a way to refer to disk
6869 partitions without having to hard-code their actual device
6870 name@footnote{Note that, while it is tempting to use
6871 @file{/dev/disk/by-uuid} and similar device names to achieve the same
6872 result, this is not recommended: These special device nodes are created
6873 by the udev daemon and may be unavailable at the time the device is
6876 However, when the source of a file system is a mapped device (@pxref{Mapped
6877 Devices}), its @code{device} field @emph{must} refer to the mapped
6878 device name---e.g., @file{/dev/mapper/root-partition}---and consequently
6879 @code{title} must be set to @code{'device}. This is required so that
6880 the system knows that mounting the file system depends on having the
6881 corresponding device mapping established.
6883 @item @code{flags} (default: @code{'()})
6884 This is a list of symbols denoting mount flags. Recognized flags
6885 include @code{read-only}, @code{bind-mount}, @code{no-dev} (disallow
6886 access to special files), @code{no-suid} (ignore setuid and setgid
6887 bits), and @code{no-exec} (disallow program execution.)
6889 @item @code{options} (default: @code{#f})
6890 This is either @code{#f}, or a string denoting mount options.
6892 @item @code{mount?} (default: @code{#t})
6893 This value indicates whether to automatically mount the file system when
6894 the system is brought up. When set to @code{#f}, the file system gets
6895 an entry in @file{/etc/fstab} (read by the @command{mount} command) but
6896 is not automatically mounted.
6898 @item @code{needed-for-boot?} (default: @code{#f})
6899 This Boolean value indicates whether the file system is needed when
6900 booting. If that is true, then the file system is mounted when the
6901 initial RAM disk (initrd) is loaded. This is always the case, for
6902 instance, for the root file system.
6904 @item @code{check?} (default: @code{#t})
6905 This Boolean indicates whether the file system needs to be checked for
6906 errors before being mounted.
6908 @item @code{create-mount-point?} (default: @code{#f})
6909 When true, the mount point is created if it does not exist yet.
6911 @item @code{dependencies} (default: @code{'()})
6912 This is a list of @code{<file-system>} objects representing file systems
6913 that must be mounted before (and unmounted after) this one.
6915 As an example, consider a hierarchy of mounts: @file{/sys/fs/cgroup} is
6916 a dependency of @file{/sys/fs/cgroup/cpu} and
6917 @file{/sys/fs/cgroup/memory}.
6922 The @code{(gnu system file-systems)} exports the following useful
6925 @defvr {Scheme Variable} %base-file-systems
6926 These are essential file systems that are required on normal systems,
6927 such as @var{%pseudo-terminal-file-system} and @var{%immutable-store} (see
6928 below.) Operating system declarations should always contain at least
6932 @defvr {Scheme Variable} %pseudo-terminal-file-system
6933 This is the file system to be mounted as @file{/dev/pts}. It supports
6934 @dfn{pseudo-terminals} created @i{via} @code{openpty} and similar
6935 functions (@pxref{Pseudo-Terminals,,, libc, The GNU C Library Reference
6936 Manual}). Pseudo-terminals are used by terminal emulators such as
6940 @defvr {Scheme Variable} %shared-memory-file-system
6941 This file system is mounted as @file{/dev/shm} and is used to support
6942 memory sharing across processes (@pxref{Memory-mapped I/O,
6943 @code{shm_open},, libc, The GNU C Library Reference Manual}).
6946 @defvr {Scheme Variable} %immutable-store
6947 This file system performs a read-only ``bind mount'' of
6948 @file{/gnu/store}, making it read-only for all the users including
6949 @code{root}. This prevents against accidental modification by software
6950 running as @code{root} or by system administrators.
6952 The daemon itself is still able to write to the store: it remounts it
6953 read-write in its own ``name space.''
6956 @defvr {Scheme Variable} %binary-format-file-system
6957 The @code{binfmt_misc} file system, which allows handling of arbitrary
6958 executable file types to be delegated to user space. This requires the
6959 @code{binfmt.ko} kernel module to be loaded.
6962 @defvr {Scheme Variable} %fuse-control-file-system
6963 The @code{fusectl} file system, which allows unprivileged users to mount
6964 and unmount user-space FUSE file systems. This requires the
6965 @code{fuse.ko} kernel module to be loaded.
6968 @node Mapped Devices
6969 @subsection Mapped Devices
6971 @cindex device mapping
6972 @cindex mapped devices
6973 The Linux kernel has a notion of @dfn{device mapping}: a block device,
6974 such as a hard disk partition, can be @dfn{mapped} into another device,
6975 with additional processing over the data that flows through
6976 it@footnote{Note that the GNU@tie{}Hurd makes no difference between the
6977 concept of a ``mapped device'' and that of a file system: both boil down
6978 to @emph{translating} input/output operations made on a file to
6979 operations on its backing store. Thus, the Hurd implements mapped
6980 devices, like file systems, using the generic @dfn{translator} mechanism
6981 (@pxref{Translators,,, hurd, The GNU Hurd Reference Manual}).}. A
6982 typical example is encryption device mapping: all writes to the mapped
6983 device are encrypted, and all reads are deciphered, transparently.
6985 Mapped devices are declared using the @code{mapped-device} form:
6989 (source "/dev/sda3")
6991 (type luks-device-mapping))
6994 Or, better yet, like this:
6998 (source (uuid "cb67fc72-0d54-4c88-9d4b-b225f30b0f44"))
7000 (type luks-device-mapping))
7003 @cindex disk encryption
7005 This example specifies a mapping from @file{/dev/sda3} to
7006 @file{/dev/mapper/home} using LUKS---the
7007 @url{http://code.google.com/p/cryptsetup,Linux Unified Key Setup}, a
7008 standard mechanism for disk encryption. In the second example, the UUID
7009 (unique identifier) is the LUKS UUID returned for the device by a
7013 cryptsetup luksUUID /dev/sdx9
7016 The @file{/dev/mapper/home}
7017 device can then be used as the @code{device} of a @code{file-system}
7018 declaration (@pxref{File Systems}). The @code{mapped-device} form is
7021 @deftp {Data Type} mapped-device
7022 Objects of this type represent device mappings that will be made when
7023 the system boots up.
7027 This string specifies the name of the block device to be mapped, such as
7031 This string specifies the name of the mapping to be established. For
7032 example, specifying @code{"my-partition"} will lead to the creation of
7033 the @code{"/dev/mapper/my-partition"} device.
7036 This must be a @code{mapped-device-kind} object, which specifies how
7037 @var{source} is mapped to @var{target}.
7041 @defvr {Scheme Variable} luks-device-mapping
7042 This defines LUKS block device encryption using the @command{cryptsetup}
7043 command from the package with the same name. It relies on the
7044 @code{dm-crypt} Linux kernel module.
7048 @subsection User Accounts
7050 User accounts and groups are entirely managed through the
7051 @code{operating-system} declaration. They are specified with the
7052 @code{user-account} and @code{user-group} forms:
7058 (supplementary-groups '("wheel" ;allow use of sudo, etc.
7060 "video" ;video devices such as webcams
7061 "cdrom")) ;the good ol' CD-ROM
7062 (comment "Bob's sister")
7063 (home-directory "/home/alice"))
7066 When booting or upon completion of @command{guix system reconfigure},
7067 the system ensures that only the user accounts and groups specified in
7068 the @code{operating-system} declaration exist, and with the specified
7069 properties. Thus, account or group creations or modifications made by
7070 directly invoking commands such as @command{useradd} are lost upon
7071 reconfiguration or reboot. This ensures that the system remains exactly
7074 @deftp {Data Type} user-account
7075 Objects of this type represent user accounts. The following members may
7080 The name of the user account.
7083 This is the name (a string) or identifier (a number) of the user group
7084 this account belongs to.
7086 @item @code{supplementary-groups} (default: @code{'()})
7087 Optionally, this can be defined as a list of group names that this
7090 @item @code{uid} (default: @code{#f})
7091 This is the user ID for this account (a number), or @code{#f}. In the
7092 latter case, a number is automatically chosen by the system when the
7095 @item @code{comment} (default: @code{""})
7096 A comment about the account, such as the account owner's full name.
7098 @item @code{home-directory}
7099 This is the name of the home directory for the account.
7101 @item @code{shell} (default: Bash)
7102 This is a G-expression denoting the file name of a program to be used as
7103 the shell (@pxref{G-Expressions}).
7105 @item @code{system?} (default: @code{#f})
7106 This Boolean value indicates whether the account is a ``system''
7107 account. System accounts are sometimes treated specially; for instance,
7108 graphical login managers do not list them.
7110 @anchor{user-account-password}
7111 @item @code{password} (default: @code{#f})
7112 You would normally leave this field to @code{#f}, initialize user
7113 passwords as @code{root} with the @command{passwd} command, and then let
7114 users change it with @command{passwd}. Passwords set with
7115 @command{passwd} are of course preserved across reboot and
7118 If you @emph{do} want to have a preset password for an account, then
7119 this field must contain the encrypted password, as a string.
7120 @xref{crypt,,, libc, The GNU C Library Reference Manual}, for more information
7121 on password encryption, and @ref{Encryption,,, guile, GNU Guile Reference
7122 Manual}, for information on Guile's @code{crypt} procedure.
7127 User group declarations are even simpler:
7130 (user-group (name "students"))
7133 @deftp {Data Type} user-group
7134 This type is for, well, user groups. There are just a few fields:
7138 The name of the group.
7140 @item @code{id} (default: @code{#f})
7141 The group identifier (a number). If @code{#f}, a new number is
7142 automatically allocated when the group is created.
7144 @item @code{system?} (default: @code{#f})
7145 This Boolean value indicates whether the group is a ``system'' group.
7146 System groups have low numerical IDs.
7148 @item @code{password} (default: @code{#f})
7149 What, user groups can have a password? Well, apparently yes. Unless
7150 @code{#f}, this field specifies the password of the group.
7155 For convenience, a variable lists all the basic user groups one may
7158 @defvr {Scheme Variable} %base-groups
7159 This is the list of basic user groups that users and/or packages expect
7160 to be present on the system. This includes groups such as ``root'',
7161 ``wheel'', and ``users'', as well as groups used to control access to
7162 specific devices such as ``audio'', ``disk'', and ``cdrom''.
7165 @defvr {Scheme Variable} %base-user-accounts
7166 This is the list of basic system accounts that programs may expect to
7167 find on a GNU/Linux system, such as the ``nobody'' account.
7169 Note that the ``root'' account is not included here. It is a
7170 special-case and is automatically added whether or not it is specified.
7177 A @dfn{locale} defines cultural conventions for a particular language
7178 and region of the world (@pxref{Locales,,, libc, The GNU C Library
7179 Reference Manual}). Each locale has a name that typically has the form
7180 @code{@var{language}_@var{territory}.@var{codeset}}---e.g.,
7181 @code{fr_LU.utf8} designates the locale for the French language, with
7182 cultural conventions from Luxembourg, and using the UTF-8 encoding.
7184 @cindex locale definition
7185 Usually, you will want to specify the default locale for the machine
7186 using the @code{locale} field of the @code{operating-system} declaration
7187 (@pxref{operating-system Reference, @code{locale}}).
7189 The selected locale is automatically added to the @dfn{locale
7190 definitions} known to the system if needed, with its codeset inferred
7191 from its name---e.g., @code{bo_CN.utf8} will be assumed to use the
7192 @code{UTF-8} codeset. Additional locale definitions can be specified in
7193 the @code{locale-definitions} slot of @code{operating-system}---this is
7194 useful, for instance, if the codeset could not be inferred from the
7195 locale name. The default set of locale definitions includes some widely
7196 used locales, but not all the available locales, in order to save space.
7198 For instance, to add the North Frisian locale for Germany, the value of
7202 (cons (locale-definition
7203 (name "fy_DE.utf8") (source "fy_DE"))
7204 %default-locale-definitions)
7207 Likewise, to save space, one might want @code{locale-definitions} to
7208 list only the locales that are actually used, as in:
7211 (list (locale-definition
7212 (name "ja_JP.eucjp") (source "ja_JP")
7213 (charset "EUC-JP")))
7217 The compiled locale definitions are available at
7218 @file{/run/current-system/locale/X.Y}, where @code{X.Y} is the libc
7219 version, which is the default location where the GNU@tie{}libc provided
7220 by Guix looks for locale data. This can be overridden using the
7221 @code{LOCPATH} environment variable (@pxref{locales-and-locpath,
7222 @code{LOCPATH} and locale packages}).
7224 The @code{locale-definition} form is provided by the @code{(gnu system
7225 locale)} module. Details are given below.
7227 @deftp {Data Type} locale-definition
7228 This is the data type of a locale definition.
7233 The name of the locale. @xref{Locale Names,,, libc, The GNU C Library
7234 Reference Manual}, for more information on locale names.
7237 The name of the source for that locale. This is typically the
7238 @code{@var{language}_@var{territory}} part of the locale name.
7240 @item @code{charset} (default: @code{"UTF-8"})
7241 The ``character set'' or ``code set'' for that locale,
7242 @uref{http://www.iana.org/assignments/character-sets, as defined by
7248 @defvr {Scheme Variable} %default-locale-definitions
7249 A list of commonly used UTF-8 locales, used as the default
7250 value of the @code{locale-definitions} field of @code{operating-system}
7254 @cindex normalized codeset in locale names
7255 These locale definitions use the @dfn{normalized codeset} for the part
7256 that follows the dot in the name (@pxref{Using gettextized software,
7257 normalized codeset,, libc, The GNU C Library Reference Manual}). So for
7258 instance it has @code{uk_UA.utf8} but @emph{not}, say,
7262 @subsubsection Locale Data Compatibility Considerations
7264 @cindex incompatibility, of locale data
7265 @code{operating-system} declarations provide a @code{locale-libcs} field
7266 to specify the GNU@tie{}libc packages that are used to compile locale
7267 declarations (@pxref{operating-system Reference}). ``Why would I
7268 care?'', you may ask. Well, it turns out that the binary format of
7269 locale data is occasionally incompatible from one libc version to
7272 @c See <https://sourceware.org/ml/libc-alpha/2015-09/msg00575.html>
7273 @c and <https://lists.gnu.org/archive/html/guix-devel/2015-08/msg00737.html>.
7274 For instance, a program linked against libc version 2.21 is unable to
7275 read locale data produced with libc 2.22; worse, that program
7276 @emph{aborts} instead of simply ignoring the incompatible locale
7277 data@footnote{Versions 2.23 and later of GNU@tie{}libc will simply skip
7278 the incompatible locale data, which is already an improvement.}.
7279 Similarly, a program linked against libc 2.22 can read most, but not
7280 all, the locale data from libc 2.21 (specifically, @code{LC_COLLATE}
7281 data is incompatible); thus calls to @code{setlocale} may fail, but
7282 programs will not abort.
7284 The ``problem'' in GuixSD is that users have a lot of freedom: They can
7285 choose whether and when to upgrade software in their profiles, and might
7286 be using a libc version different from the one the system administrator
7287 used to build the system-wide locale data.
7289 Fortunately, unprivileged users can also install their own locale data
7290 and define @var{GUIX_LOCPATH} accordingly (@pxref{locales-and-locpath,
7291 @code{GUIX_LOCPATH} and locale packages}).
7293 Still, it is best if the system-wide locale data at
7294 @file{/run/current-system/locale} is built for all the libc versions
7295 actually in use on the system, so that all the programs can access
7296 it---this is especially crucial on a multi-user system. To do that, the
7297 administrator can specify several libc packages in the
7298 @code{locale-libcs} field of @code{operating-system}:
7301 (use-package-modules base)
7305 (locale-libcs (list glibc-2.21 (canonical-package glibc))))
7308 This example would lead to a system containing locale definitions for
7309 both libc 2.21 and the current version of libc in
7310 @file{/run/current-system/locale}.
7314 @subsection Services
7316 @cindex system services
7317 An important part of preparing an @code{operating-system} declaration is
7318 listing @dfn{system services} and their configuration (@pxref{Using the
7319 Configuration System}). System services are typically daemons launched
7320 when the system boots, or other actions needed at that time---e.g.,
7321 configuring network access.
7323 Services are managed by the GNU@tie{}Shepherd (@pxref{Introduction,,,
7324 shepherd, The GNU Shepherd Manual}). On a running system, the
7325 @command{herd} command allows you to list the available services, show
7326 their status, start and stop them, or do other specific operations
7327 (@pxref{Jump Start,,, shepherd, The GNU Shepherd Manual}). For example:
7333 The above command, run as @code{root}, lists the currently defined
7334 services. The @command{herd doc} command shows a synopsis of the given
7339 Run libc's name service cache daemon (nscd).
7342 The @command{start}, @command{stop}, and @command{restart} sub-commands
7343 have the effect you would expect. For instance, the commands below stop
7344 the nscd service and restart the Xorg display server:
7348 Service nscd has been stopped.
7349 # herd restart xorg-server
7350 Service xorg-server has been stopped.
7351 Service xorg-server has been started.
7354 The following sections document the available services, starting with
7355 the core services, that may be used in an @code{operating-system}
7359 * Base Services:: Essential system services.
7360 * Scheduled Job Execution:: The mcron service.
7361 * Networking Services:: Network setup, SSH daemon, etc.
7362 * X Window:: Graphical display.
7363 * Desktop Services:: D-Bus and desktop services.
7364 * Database Services:: SQL databases.
7365 * Mail Services:: IMAP, POP3, SMTP, and all that.
7366 * Web Services:: Web servers.
7367 * Various Services:: Other services.
7371 @subsubsection Base Services
7373 The @code{(gnu services base)} module provides definitions for the basic
7374 services that one expects from the system. The services exported by
7375 this module are listed below.
7377 @defvr {Scheme Variable} %base-services
7378 This variable contains a list of basic services (@pxref{Service Types
7379 and Services}, for more information on service objects) one would
7380 expect from the system: a login service (mingetty) on each tty, syslogd,
7381 the libc name service cache daemon (nscd), the udev device manager, and
7384 This is the default value of the @code{services} field of
7385 @code{operating-system} declarations. Usually, when customizing a
7386 system, you will want to append services to @var{%base-services}, like
7390 (cons* (avahi-service) (lsh-service) %base-services)
7394 @deffn {Scheme Procedure} host-name-service @var{name}
7395 Return a service that sets the host name to @var{name}.
7398 @deffn {Scheme Procedure} mingetty-service @var{config}
7399 Return a service to run mingetty according to @var{config}, a
7400 @code{<mingetty-configuration>} object, which specifies the tty to run, among
7404 @deftp {Data Type} mingetty-configuration
7405 This is the data type representing the configuration of Mingetty, which
7406 implements console log-in.
7411 The name of the console this Mingetty runs on---e.g., @code{"tty1"}.
7414 A file-like object containing the ``message of the day''.
7416 @item @code{auto-login} (default: @code{#f})
7417 When true, this field must be a string denoting the user name under
7418 which the system automatically logs in. When it is @code{#f}, a
7419 user name and password must be entered to log in.
7421 @item @code{login-program} (default: @code{#f})
7422 This must be either @code{#f}, in which case the default log-in program
7423 is used (@command{login} from the Shadow tool suite), or a gexp denoting
7424 the name of the log-in program.
7426 @item @code{login-pause?} (default: @code{#f})
7427 When set to @code{#t} in conjunction with @var{auto-login}, the user
7428 will have to press a key before the log-in shell is launched.
7430 @item @code{mingetty} (default: @var{mingetty})
7431 The Mingetty package to use.
7436 @cindex name service cache daemon
7438 @deffn {Scheme Procedure} nscd-service [@var{config}] [#:glibc glibc] @
7439 [#:name-services '()]
7440 Return a service that runs the libc name service cache daemon (nscd) with the
7441 given @var{config}---an @code{<nscd-configuration>} object. @xref{Name
7442 Service Switch}, for an example.
7445 @defvr {Scheme Variable} %nscd-default-configuration
7446 This is the default @code{<nscd-configuration>} value (see below) used
7447 by @code{nscd-service}. It uses the caches defined by
7448 @var{%nscd-default-caches}; see below.
7451 @deftp {Data Type} nscd-configuration
7452 This is the data type representing the name service cache daemon (nscd)
7457 @item @code{name-services} (default: @code{'()})
7458 List of packages denoting @dfn{name services} that must be visible to
7459 the nscd---e.g., @code{(list @var{nss-mdns})}.
7461 @item @code{glibc} (default: @var{glibc})
7462 Package object denoting the GNU C Library providing the @command{nscd}
7465 @item @code{log-file} (default: @code{"/var/log/nscd.log"})
7466 Name of the nscd log file. This is where debugging output goes when
7467 @code{debug-level} is strictly positive.
7469 @item @code{debug-level} (default: @code{0})
7470 Integer denoting the debugging levels. Higher numbers mean that more
7471 debugging output is logged.
7473 @item @code{caches} (default: @var{%nscd-default-caches})
7474 List of @code{<nscd-cache>} objects denoting things to be cached; see
7480 @deftp {Data Type} nscd-cache
7481 Data type representing a cache database of nscd and its parameters.
7485 @item @code{database}
7486 This is a symbol representing the name of the database to be cached.
7487 Valid values are @code{passwd}, @code{group}, @code{hosts}, and
7488 @code{services}, which designate the corresponding NSS database
7489 (@pxref{NSS Basics,,, libc, The GNU C Library Reference Manual}).
7491 @item @code{positive-time-to-live}
7492 @itemx @code{negative-time-to-live} (default: @code{20})
7493 A number representing the number of seconds during which a positive or
7494 negative lookup result remains in cache.
7496 @item @code{check-files?} (default: @code{#t})
7497 Whether to check for updates of the files corresponding to
7500 For instance, when @var{database} is @code{hosts}, setting this flag
7501 instructs nscd to check for updates in @file{/etc/hosts} and to take
7504 @item @code{persistent?} (default: @code{#t})
7505 Whether the cache should be stored persistently on disk.
7507 @item @code{shared?} (default: @code{#t})
7508 Whether the cache should be shared among users.
7510 @item @code{max-database-size} (default: 32@tie{}MiB)
7511 Maximum size in bytes of the database cache.
7513 @c XXX: 'suggested-size' and 'auto-propagate?' seem to be expert
7514 @c settings, so leave them out.
7519 @defvr {Scheme Variable} %nscd-default-caches
7520 List of @code{<nscd-cache>} objects used by default by
7521 @code{nscd-configuration} (see above).
7523 It enables persistent and aggressive caching of service and host name
7524 lookups. The latter provides better host name lookup performance,
7525 resilience in the face of unreliable name servers, and also better
7526 privacy---often the result of host name lookups is in local cache, so
7527 external name servers do not even need to be queried.
7531 @deffn {Scheme Procedure} syslog-service @
7532 [#:config-file @var{%default-syslog.conf}]
7533 Return a service that runs @command{syslogd}. If the configuration file
7534 name @var{config-file} is not specified, use some reasonable default
7537 @xref{syslogd invocation,,, inetutils, GNU Inetutils}, for more
7538 information on the configuration file syntax.
7541 @anchor{guix-configuration-type}
7542 @deftp {Data Type} guix-configuration
7543 This data type represents the configuration of the Guix build daemon.
7544 @xref{Invoking guix-daemon}, for more information.
7547 @item @code{guix} (default: @var{guix})
7548 The Guix package to use.
7550 @item @code{build-group} (default: @code{"guixbuild"})
7551 Name of the group for build user accounts.
7553 @item @code{build-accounts} (default: @code{10})
7554 Number of build user accounts to create.
7556 @item @code{authorize-key?} (default: @code{#t})
7557 Whether to authorize the substitute key for @code{hydra.gnu.org}
7558 (@pxref{Substitutes}).
7560 @item @code{use-substitutes?} (default: @code{#t})
7561 Whether to use substitutes.
7563 @item @code{substitute-urls} (default: @var{%default-substitute-urls})
7564 The list of URLs where to look for substitutes by default.
7566 @item @code{extra-options} (default: @code{'()})
7567 List of extra command-line options for @command{guix-daemon}.
7569 @item @code{lsof} (default: @var{lsof})
7570 @itemx @code{lsh} (default: @var{lsh})
7571 The lsof and lsh packages to use.
7576 @deffn {Scheme Procedure} guix-service @var{config}
7577 Return a service that runs the Guix build daemon according to
7581 @deffn {Scheme Procedure} udev-service [#:udev udev]
7582 Run @var{udev}, which populates the @file{/dev} directory dynamically.
7585 @deffn {Scheme Procedure} urandom-seed-service @var{#f}
7586 Save some entropy in @var{%random-seed-file} to seed @file{/dev/urandom}
7590 @defvr {Scheme Variable} %random-seed-file
7591 This is the name of the file where some random bytes are saved by
7592 @var{urandom-seed-service} to seed @file{/dev/urandom} when rebooting.
7593 It defaults to @file{/var/lib/random-seed}.
7596 @deffn {Scheme Procedure} console-keymap-service @var{files} ...
7597 @cindex keyboard layout
7598 Return a service to load console keymaps from @var{files} using
7599 @command{loadkeys} command. Most likely, you want to load some default
7600 keymap, which can be done like this:
7603 (console-keymap-service "dvorak")
7606 Or, for example, for a Swedish keyboard, you may need to combine
7607 the following keymaps:
7609 (console-keymap-service "se-lat6" "se-fi-lat6")
7612 Also you can specify a full file name (or file names) of your keymap(s).
7613 See @code{man loadkeys} for details.
7617 @deffn {Scheme Procedure} gpm-service [#:gpm @var{gpm}] @
7619 Run @var{gpm}, the general-purpose mouse daemon, with the given
7620 command-line @var{options}. GPM allows users to use the mouse in the console,
7621 notably to select, copy, and paste text. The default value of @var{options}
7622 uses the @code{ps2} protocol, which works for both USB and PS/2 mice.
7624 This service is not part of @var{%base-services}.
7627 @anchor{guix-publish-service}
7628 @deffn {Scheme Procedure} guix-publish-service [#:guix @var{guix}] @
7629 [#:port 80] [#:host "localhost"]
7630 Return a service that runs @command{guix publish} listening on @var{host}
7631 and @var{port} (@pxref{Invoking guix publish}).
7633 This assumes that @file{/etc/guix} already contains a signing key pair as
7634 created by @command{guix archive --generate-key} (@pxref{Invoking guix
7635 archive}). If that is not the case, the service will fail to start.
7638 @anchor{rngd-service}
7639 @deffn {Scheme Procedure} rngd-service [#:rng-tools @var{rng-tools}] @
7640 [#:device "/dev/hwrng"]
7641 Return a service that runs the @command{rngd} program from @var{rng-tools}
7642 to add @var{device} to the kernel's entropy pool. The service will fail if
7643 @var{device} does not exist.
7646 @anchor{pam-limits-service}
7647 @cindex session limits
7650 @deffn {Scheme Procedure} pam-limits-service [#:limits @var{limits}]
7652 Return a service that installs a configuration file for the
7653 @uref{http://linux-pam.org/Linux-PAM-html/sag-pam_limits.html,
7654 @code{pam_limits} module}. The procedure optionally takes a list of
7655 @code{pam-limits-entry} values, which can be used to specify
7656 @code{ulimit} limits and nice priority limits to user sessions.
7658 The following limits definition sets two hard and soft limits for all
7659 login sessions of users in the @code{realtime} group:
7664 (pam-limits-entry "@@realtime" 'both 'rtprio 99)
7665 (pam-limits-entry "@@realtime" 'both 'memlock 'unlimited)))
7668 The first entry increases the maximum realtime priority for
7669 non-privileged processes; the second entry lifts any restriction of the
7670 maximum address space that can be locked in memory. These settings are
7671 commonly used for real-time audio systems.
7674 @node Scheduled Job Execution
7675 @subsubsection Scheduled Job Execution
7678 @cindex scheduling jobs
7679 The @code{(gnu services mcron)} module provides an interface to
7680 GNU@tie{}mcron, a daemon to run jobs at scheduled times (@pxref{Top,,,
7681 mcron, GNU@tie{}mcron}). GNU@tie{}mcron is similar to the traditional
7682 Unix @command{cron} daemon; the main difference is that it is
7683 implemented in Guile Scheme, which provides a lot of flexibility when
7684 specifying the scheduling of jobs and their actions.
7686 The example below defines an operating system that runs the
7687 @command{updatedb} (@pxref{Invoking updatedb,,, find, Finding Files})
7688 and the @command{guix gc} commands (@pxref{Invoking guix gc}) daily, as
7689 well as the @command{mkid} command on behalf of an unprivileged user
7690 (@pxref{mkid invocation,,, idutils, ID Database Utilities}). It uses
7691 gexps to introduce job definitions that are passed to mcron
7692 (@pxref{G-Expressions}).
7695 (use-modules (guix) (gnu) (gnu services mcron))
7696 (use-package-modules base idutils)
7698 (define updatedb-job
7699 ;; Run 'updatedb' at 3AM every day. Here we write the
7700 ;; job's action as a Scheme procedure.
7701 #~(job '(next-hour '(3))
7703 (execl (string-append #$findutils "/bin/updatedb")
7705 "--prunepaths=/tmp /var/tmp /gnu/store"))))
7707 (define garbage-collector-job
7708 ;; Collect garbage 5 minutes after midnight every day.
7709 ;; The job's action is a shell command.
7710 #~(job "5 0 * * *" ;Vixie cron syntax
7713 (define idutils-jobs
7714 ;; Update the index database as user "charlie" at 12:15PM
7715 ;; and 19:15PM. This runs from the user's home directory.
7716 #~(job '(next-minute-from (next-hour '(12 19)) '(15))
7717 (string-append #$idutils "/bin/mkid src")
7722 (services (cons (mcron-service (list garbage-collector-job
7728 @xref{Guile Syntax, mcron job specifications,, mcron, GNU@tie{}mcron},
7729 for more information on mcron job specifications. Below is the
7730 reference of the mcron service.
7732 @deffn {Scheme Procedure} mcron-service @var{jobs} [#:mcron @var{mcron2}]
7733 Return an mcron service running @var{mcron} that schedules @var{jobs}, a
7734 list of gexps denoting mcron job specifications.
7736 This is a shorthand for:
7738 (service mcron-service-type
7739 (mcron-configuration (mcron mcron) (jobs jobs)))
7743 @defvr {Scheme Variable} mcron-service-type
7744 This is the type of the @code{mcron} service, whose value is an
7745 @code{mcron-configuration} object.
7747 This service type can be the target of a service extension that provides
7748 it additional job specifications (@pxref{Service Composition}). In
7749 other words, it is possible to define services that provide addition
7753 @deftp {Data Type} mcron-configuration
7754 Data type representing the configuration of mcron.
7757 @item @code{mcron} (default: @var{mcron2})
7758 The mcron package to use.
7761 This is a list of gexps (@pxref{G-Expressions}), where each gexp
7762 corresponds to an mcron job specification (@pxref{Syntax, mcron job
7763 specifications,, mcron, GNU@tie{}mcron}).
7768 @node Networking Services
7769 @subsubsection Networking Services
7771 The @code{(gnu services networking)} module provides services to configure
7772 the network interface.
7774 @cindex DHCP, networking service
7775 @deffn {Scheme Procedure} dhcp-client-service [#:dhcp @var{isc-dhcp}]
7776 Return a service that runs @var{dhcp}, a Dynamic Host Configuration
7777 Protocol (DHCP) client, on all the non-loopback network interfaces.
7780 @deffn {Scheme Procedure} static-networking-service @var{interface} @var{ip} @
7781 [#:gateway #f] [#:name-servers @code{'()}]
7782 Return a service that starts @var{interface} with address @var{ip}. If
7783 @var{gateway} is true, it must be a string specifying the default network
7788 @cindex network management
7789 @deffn {Scheme Procedure} wicd-service [#:wicd @var{wicd}]
7790 Return a service that runs @url{https://launchpad.net/wicd,Wicd}, a network
7791 management daemon that aims to simplify wired and wireless networking.
7793 This service adds the @var{wicd} package to the global profile, providing
7794 several commands to interact with the daemon and configure networking:
7795 @command{wicd-client}, a graphical user interface, and the @command{wicd-cli}
7796 and @command{wicd-curses} user interfaces.
7799 @cindex NetworkManager
7800 @deffn {Scheme Procedure} network-manager-service @
7801 [#:network-manager @var{network-manager}]
7802 Return a service that runs NetworkManager, a network connection manager
7803 attempting to keep network connectivity active when available.
7807 @deffn {Scheme Procedure} connman-service @
7808 [#:connman @var{connman}]
7809 Return a service that runs @url{https://01.org/connman,Connman}, a network
7812 This service adds the @var{connman} package to the global profile, providing
7813 several the @command{connmanctl} command to interact with the daemon and
7814 configure networking."
7817 @deffn {Scheme Procedure} ntp-service [#:ntp @var{ntp}] @
7818 [#:name-service @var{%ntp-servers}]
7819 Return a service that runs the daemon from @var{ntp}, the
7820 @uref{http://www.ntp.org, Network Time Protocol package}. The daemon will
7821 keep the system clock synchronized with that of @var{servers}.
7824 @defvr {Scheme Variable} %ntp-servers
7825 List of host names used as the default NTP servers.
7828 @deffn {Scheme Procedure} tor-service [@var{config-file}] [#:tor @var{tor}]
7829 Return a service to run the @uref{https://torproject.org, Tor} anonymous
7832 The daemon runs as the @code{tor} unprivileged user. It is passed
7833 @var{config-file}, a file-like object, with an additional @code{User tor} line
7834 and lines for hidden services added via @code{tor-hidden-service}. Run
7835 @command{man tor} for information about the configuration file.
7838 @cindex hidden service
7839 @deffn {Scheme Procedure} tor-hidden-service @var{name} @var{mapping}
7840 Define a new Tor @dfn{hidden service} called @var{name} and implementing
7841 @var{mapping}. @var{mapping} is a list of port/host tuples, such as:
7844 '((22 "127.0.0.1:22")
7845 (80 "127.0.0.1:8080"))
7848 In this example, port 22 of the hidden service is mapped to local port 22, and
7849 port 80 is mapped to local port 8080.
7851 This creates a @file{/var/lib/tor/hidden-services/@var{name}} directory, where
7852 the @file{hostname} file contains the @code{.onion} host name for the hidden
7855 See @uref{https://www.torproject.org/docs/tor-hidden-service.html.en, the Tor
7856 project's documentation} for more information.
7859 @deffn {Scheme Procedure} bitlbee-service [#:bitlbee bitlbee] @
7860 [#:interface "127.0.0.1"] [#:port 6667] @
7861 [#:extra-settings ""]
7862 Return a service that runs @url{http://bitlbee.org,BitlBee}, a daemon that
7863 acts as a gateway between IRC and chat networks.
7865 The daemon will listen to the interface corresponding to the IP address
7866 specified in @var{interface}, on @var{port}. @code{127.0.0.1} means that only
7867 local clients can connect, whereas @code{0.0.0.0} means that connections can
7868 come from any networking interface.
7870 In addition, @var{extra-settings} specifies a string to append to the
7874 Furthermore, @code{(gnu services ssh)} provides the following services.
7876 @deffn {Scheme Procedure} lsh-service [#:host-key "/etc/lsh/host-key"] @
7877 [#:daemonic? #t] [#:interfaces '()] [#:port-number 22] @
7878 [#:allow-empty-passwords? #f] [#:root-login? #f] @
7879 [#:syslog-output? #t] [#:x11-forwarding? #t] @
7880 [#:tcp/ip-forwarding? #t] [#:password-authentication? #t] @
7881 [#:public-key-authentication? #t] [#:initialize? #t]
7882 Run the @command{lshd} program from @var{lsh} to listen on port @var{port-number}.
7883 @var{host-key} must designate a file containing the host key, and readable
7886 When @var{daemonic?} is true, @command{lshd} will detach from the
7887 controlling terminal and log its output to syslogd, unless one sets
7888 @var{syslog-output?} to false. Obviously, it also makes lsh-service
7889 depend on existence of syslogd service. When @var{pid-file?} is true,
7890 @command{lshd} writes its PID to the file called @var{pid-file}.
7892 When @var{initialize?} is true, automatically create the seed and host key
7893 upon service activation if they do not exist yet. This may take long and
7894 require interaction.
7896 When @var{initialize?} is false, it is up to the user to initialize the
7897 randomness generator (@pxref{lsh-make-seed,,, lsh, LSH Manual}), and to create
7898 a key pair with the private key stored in file @var{host-key} (@pxref{lshd
7899 basics,,, lsh, LSH Manual}).
7901 When @var{interfaces} is empty, lshd listens for connections on all the
7902 network interfaces; otherwise, @var{interfaces} must be a list of host names
7905 @var{allow-empty-passwords?} specifies whether to accept log-ins with empty
7906 passwords, and @var{root-login?} specifies whether to accept log-ins as
7909 The other options should be self-descriptive.
7912 @deffn {Scheme Procedure} dropbear-service [@var{config}]
7913 Run the @uref{https://matt.ucc.asn.au/dropbear/dropbear.html,Dropbear SSH
7914 daemon} with the given @var{config}, a @code{<dropbear-configuration>}
7917 For example, to specify a Dropbear service listening on port 1234, add
7918 this call to the operating system's @code{services} field:
7921 (dropbear-service (dropbear-configuration
7922 (port-number 1234)))
7926 @deftp {Data Type} dropbear-configuration
7927 This data type represents the configuration of a Dropbear SSH daemon.
7930 @item @code{dropbear} (default: @var{dropbear})
7931 The Dropbear package to use.
7933 @item @code{port-number} (default: 22)
7934 The TCP port where the daemon waits for incoming connections.
7936 @item @code{syslog-output?} (default: @code{#t})
7937 Whether to enable syslog output.
7939 @item @code{pid-file} (default: @code{"/var/run/dropbear.pid"})
7940 File name of the daemon's PID file.
7942 @item @code{root-login?} (default: @code{#f})
7943 Whether to allow @code{root} logins.
7945 @item @code{allow-empty-passwords?} (default: @code{#f})
7946 Whether to allow empty passwords.
7948 @item @code{password-authentication?} (default: @code{#t})
7949 Whether to enable password-based authentication.
7953 @defvr {Scheme Variable} %facebook-host-aliases
7954 This variable contains a string for use in @file{/etc/hosts}
7955 (@pxref{Host Names,,, libc, The GNU C Library Reference Manual}). Each
7956 line contains a entry that maps a known server name of the Facebook
7957 on-line service---e.g., @code{www.facebook.com}---to the local
7958 host---@code{127.0.0.1} or its IPv6 equivalent, @code{::1}.
7960 This variable is typically used in the @code{hosts-file} field of an
7961 @code{operating-system} declaration (@pxref{operating-system Reference,
7962 @file{/etc/hosts}}):
7965 (use-modules (gnu) (guix))
7968 (host-name "mymachine")
7971 ;; Create a /etc/hosts file with aliases for "localhost"
7972 ;; and "mymachine", as well as for Facebook servers.
7974 (string-append (local-host-aliases host-name)
7975 %facebook-host-aliases))))
7978 This mechanism can prevent programs running locally, such as Web
7979 browsers, from accessing Facebook.
7982 The @code{(gnu services avahi)} provides the following definition.
7984 @deffn {Scheme Procedure} avahi-service [#:avahi @var{avahi}] @
7985 [#:host-name #f] [#:publish? #t] [#:ipv4? #t] @
7986 [#:ipv6? #t] [#:wide-area? #f] @
7987 [#:domains-to-browse '()] [#:debug? #f]
7988 Return a service that runs @command{avahi-daemon}, a system-wide
7989 mDNS/DNS-SD responder that allows for service discovery and
7990 "zero-configuration" host name lookups (see @uref{http://avahi.org/}), and
7991 extends the name service cache daemon (nscd) so that it can resolve
7992 @code{.local} host names using
7993 @uref{http://0pointer.de/lennart/projects/nss-mdns/, nss-mdns}. Additionally,
7994 add the @var{avahi} package to the system profile so that commands such as
7995 @command{avahi-browse} are directly usable.
7997 If @var{host-name} is different from @code{#f}, use that as the host name to
7998 publish for this machine; otherwise, use the machine's actual host name.
8000 When @var{publish?} is true, publishing of host names and services is allowed;
8001 in particular, avahi-daemon will publish the machine's host name and IP
8002 address via mDNS on the local network.
8004 When @var{wide-area?} is true, DNS-SD over unicast DNS is enabled.
8006 Boolean values @var{ipv4?} and @var{ipv6?} determine whether to use IPv4/IPv6
8012 @subsubsection X Window
8014 Support for the X Window graphical display system---specifically
8015 Xorg---is provided by the @code{(gnu services xorg)} module. Note that
8016 there is no @code{xorg-service} procedure. Instead, the X server is
8017 started by the @dfn{login manager}, currently SLiM.
8019 @deffn {Scheme Procedure} slim-service [#:allow-empty-passwords? #f] @
8020 [#:auto-login? #f] [#:default-user ""] [#:startx] @
8021 [#:theme @var{%default-slim-theme}] @
8022 [#:theme-name @var{%default-slim-theme-name}]
8023 Return a service that spawns the SLiM graphical login manager, which in
8024 turn starts the X display server with @var{startx}, a command as returned by
8025 @code{xorg-start-command}.
8029 SLiM automatically looks for session types described by the @file{.desktop}
8030 files in @file{/run/current-system/profile/share/xsessions} and allows users
8031 to choose a session from the log-in screen using @kbd{F1}. Packages such as
8032 @var{xfce}, @var{sawfish}, and @var{ratpoison} provide @file{.desktop} files;
8033 adding them to the system-wide set of packages automatically makes them
8034 available at the log-in screen.
8036 In addition, @file{~/.xsession} files are honored. When available,
8037 @file{~/.xsession} must be an executable that starts a window manager
8038 and/or other X clients.
8040 When @var{allow-empty-passwords?} is true, allow logins with an empty
8041 password. When @var{auto-login?} is true, log in automatically as
8044 If @var{theme} is @code{#f}, use the default log-in theme; otherwise
8045 @var{theme} must be a gexp denoting the name of a directory containing the
8046 theme to use. In that case, @var{theme-name} specifies the name of the
8050 @defvr {Scheme Variable} %default-theme
8051 @defvrx {Scheme Variable} %default-theme-name
8052 The G-Expression denoting the default SLiM theme and its name.
8055 @deffn {Scheme Procedure} xorg-start-command [#:guile] @
8056 [#:configuration-file #f] [#:xorg-server @var{xorg-server}]
8057 Return a derivation that builds a @var{guile} script to start the X server
8058 from @var{xorg-server}. @var{configuration-file} is the server configuration
8059 file or a derivation that builds it; when omitted, the result of
8060 @code{xorg-configuration-file} is used.
8062 Usually the X server is started by a login manager.
8065 @deffn {Scheme Procedure} xorg-configuration-file @
8066 [#:drivers '()] [#:resolutions '()] [#:extra-config '()]
8067 Return a configuration file for the Xorg server containing search paths for
8068 all the common drivers.
8070 @var{drivers} must be either the empty list, in which case Xorg chooses a
8071 graphics driver automatically, or a list of driver names that will be tried in
8072 this order---e.g., @code{(\"modesetting\" \"vesa\")}.
8074 Likewise, when @var{resolutions} is the empty list, Xorg chooses an
8075 appropriate screen resolution; otherwise, it must be a list of
8076 resolutions---e.g., @code{((1024 768) (640 480))}.
8078 Last, @var{extra-config} is a list of strings or objects appended to the
8079 @code{text-file*} argument list. It is used to pass extra text to be added
8080 verbatim to the configuration file.
8083 @deffn {Scheme Procedure} screen-locker-service @var{package} [@var{name}]
8084 Add @var{package}, a package for a screen-locker or screen-saver whose
8085 command is @var{program}, to the set of setuid programs and add a PAM entry
8086 for it. For example:
8089 (screen-locker-service xlockmore "xlock")
8092 makes the good ol' XlockMore usable.
8096 @node Desktop Services
8097 @subsubsection Desktop Services
8099 The @code{(gnu services desktop)} module provides services that are
8100 usually useful in the context of a ``desktop'' setup---that is, on a
8101 machine running a graphical display server, possibly with graphical user
8102 interfaces, etc. It also defines services that provide specific desktop
8103 environments like GNOME and XFCE.
8105 To simplify things, the module defines a variable containing the set of
8106 services that users typically expect on a machine with a graphical
8107 environment and networking:
8109 @defvr {Scheme Variable} %desktop-services
8110 This is a list of services that builds upon @var{%base-services} and
8111 adds or adjusts services for a typical ``desktop'' setup.
8113 In particular, it adds a graphical login manager (@pxref{X Window,
8114 @code{slim-service}}), screen lockers,
8115 a network management tool (@pxref{Networking
8116 Services, @code{wicd-service}}), energy and color management services,
8117 the @code{elogind} login and seat manager, the Polkit privilege service,
8118 the GeoClue location service, an NTP client (@pxref{Networking
8119 Services}), the Avahi daemon, and has the name service switch service
8120 configured to be able to use @code{nss-mdns} (@pxref{Name Service
8124 The @var{%desktop-services} variable can be used as the @code{services}
8125 field of an @code{operating-system} declaration (@pxref{operating-system
8126 Reference, @code{services}}).
8128 Additionally, the @code{gnome-desktop-service} and
8129 @code{xfce-desktop-service} procedures can add GNOME and/or XFCE to a
8130 system. To ``add GNOME'' means that system-level services like the
8131 backlight adjustment helpers and the power management utilities are
8132 added to the system, extending @code{polkit} and @code{dbus}
8133 appropriately, allowing GNOME to operate with elevated privileges on a
8134 limited number of special-purpose system interfaces. Additionally,
8135 adding a service made by @code{gnome-desktop-service} adds the GNOME
8136 metapackage to the system profile. Likewise, adding the XFCE service
8137 not only adds the @code{xfce} metapackage to the system profile, but it
8138 also gives the Thunar file manager the ability to open a ``root-mode''
8139 file management window, if the user authenticates using the
8140 administrator's password via the standard polkit graphical interface.
8142 @deffn {Scheme Procedure} gnome-desktop-service
8143 Return a service that adds the @code{gnome} package to the system
8144 profile, and extends polkit with the actions from
8145 @code{gnome-settings-daemon}.
8148 @deffn {Scheme Procedure} xfce-desktop-service
8149 Return a service that adds the @code{xfce} package to the system profile,
8150 and extends polkit with the abilit for @code{thunar} to manipulate the
8151 file system as root from within a user session, after the user has
8152 authenticated with the administrator's password.
8155 Because the GNOME and XFCE desktop services pull in so many packages,
8156 the default @code{%desktop-services} variable doesn't include either of
8157 them by default. To add GNOME or XFCE, just @code{cons} them onto
8158 @code{%desktop-services} in the @code{services} field of your
8159 @code{operating-system}:
8163 (use-service-modules desktop)
8166 ;; cons* adds items to the list given as its last argument.
8167 (services (cons* (gnome-desktop-service)
8168 (xfce-desktop-service)
8173 These desktop environments will then be available as options in the
8174 graphical login window.
8176 The actual service definitions included in @code{%desktop-services} and
8177 provided by @code{(gnu services dbus)} and @code{(gnu services desktop)}
8178 are described below.
8180 @deffn {Scheme Procedure} dbus-service [#:dbus @var{dbus}] [#:services '()]
8181 Return a service that runs the ``system bus'', using @var{dbus}, with
8182 support for @var{services}.
8184 @uref{http://dbus.freedesktop.org/, D-Bus} is an inter-process communication
8185 facility. Its system bus is used to allow system services to communicate
8186 and to be notified of system-wide events.
8188 @var{services} must be a list of packages that provide an
8189 @file{etc/dbus-1/system.d} directory containing additional D-Bus configuration
8190 and policy files. For example, to allow avahi-daemon to use the system bus,
8191 @var{services} must be equal to @code{(list avahi)}.
8194 @deffn {Scheme Procedure} elogind-service [#:config @var{config}]
8195 Return a service that runs the @code{elogind} login and
8196 seat management daemon. @uref{https://github.com/andywingo/elogind,
8197 Elogind} exposes a D-Bus interface that can be used to know which users
8198 are logged in, know what kind of sessions they have open, suspend the
8199 system, inhibit system suspend, reboot the system, and other tasks.
8201 Elogind handles most system-level power events for a computer, for
8202 example suspending the system when a lid is closed, or shutting it down
8203 when the power button is pressed.
8205 The @var{config} keyword argument specifies the configuration for
8206 elogind, and should be the result of an @code{(elogind-configuration
8207 (@var{parameter} @var{value})...)} invocation. Available parameters and
8208 their default values are:
8211 @item kill-user-processes?
8213 @item kill-only-users
8215 @item kill-exclude-users
8217 @item inhibit-delay-max-seconds
8219 @item handle-power-key
8221 @item handle-suspend-key
8223 @item handle-hibernate-key
8225 @item handle-lid-switch
8227 @item handle-lid-switch-docked
8229 @item power-key-ignore-inhibited?
8231 @item suspend-key-ignore-inhibited?
8233 @item hibernate-key-ignore-inhibited?
8235 @item lid-switch-ignore-inhibited?
8237 @item holdoff-timeout-seconds
8241 @item idle-action-seconds
8243 @item runtime-directory-size-percent
8245 @item runtime-directory-size
8250 @code{("mem" "standby" "freeze")}
8253 @item hibernate-state
8255 @item hibernate-mode
8256 @code{("platform" "shutdown")}
8257 @item hybrid-sleep-state
8259 @item hybrid-sleep-mode
8260 @code{("suspend" "platform" "shutdown")}
8264 @deffn {Scheme Procedure} polkit-service @
8265 [#:polkit @var{polkit}]
8266 Return a service that runs the
8267 @uref{http://www.freedesktop.org/wiki/Software/polkit/, Polkit privilege
8268 management service}, which allows system administrators to grant access to
8269 privileged operations in a structured way. By querying the Polkit service, a
8270 privileged system component can know when it should grant additional
8271 capabilities to ordinary users. For example, an ordinary user can be granted
8272 the capability to suspend the system if the user is logged in locally.
8275 @deffn {Scheme Procedure} upower-service [#:upower @var{upower}] @
8276 [#:watts-up-pro? #f] @
8277 [#:poll-batteries? #t] @
8278 [#:ignore-lid? #f] @
8279 [#:use-percentage-for-policy? #f] @
8280 [#:percentage-low 10] @
8281 [#:percentage-critical 3] @
8282 [#:percentage-action 2] @
8284 [#:time-critical 300] @
8285 [#:time-action 120] @
8286 [#:critical-power-action 'hybrid-sleep]
8287 Return a service that runs @uref{http://upower.freedesktop.org/,
8288 @command{upowerd}}, a system-wide monitor for power consumption and battery
8289 levels, with the given configuration settings. It implements the
8290 @code{org.freedesktop.UPower} D-Bus interface, and is notably used by
8294 @deffn {Scheme Procedure} udisks-service [#:udisks @var{udisks}]
8295 Return a service for @uref{http://udisks.freedesktop.org/docs/latest/,
8296 UDisks}, a @dfn{disk management} daemon that provides user interfaces with
8297 notifications and ways to mount/unmount disks. Programs that talk to UDisks
8298 include the @command{udisksctl} command, part of UDisks, and GNOME Disks.
8301 @deffn {Scheme Procedure} colord-service [#:colord @var{colord}]
8302 Return a service that runs @command{colord}, a system service with a D-Bus
8303 interface to manage the color profiles of input and output devices such as
8304 screens and scanners. It is notably used by the GNOME Color Manager graphical
8305 tool. See @uref{http://www.freedesktop.org/software/colord/, the colord web
8306 site} for more information.
8309 @deffn {Scheme Procedure} geoclue-application name [#:allowed? #t] [#:system? #f] [#:users '()]
8310 Return a configuration allowing an application to access GeoClue
8311 location data. @var{name} is the Desktop ID of the application, without
8312 the @code{.desktop} part. If @var{allowed?} is true, the application
8313 will have access to location information by default. The boolean
8314 @var{system?} value indicates whether an application is a system component
8315 or not. Finally @var{users} is a list of UIDs of all users for which
8316 this application is allowed location info access. An empty users list
8317 means that all users are allowed.
8320 @defvr {Scheme Variable} %standard-geoclue-applications
8321 The standard list of well-known GeoClue application configurations,
8322 granting authority to the GNOME date-and-time utility to ask for the
8323 current location in order to set the time zone, and allowing the
8324 IceCat and Epiphany web browsers to request location information.
8325 IceCat and Epiphany both query the user before allowing a web page to
8326 know the user's location.
8329 @deffn {Scheme Procedure} geoclue-service [#:colord @var{colord}] @
8331 [#:wifi-geolocation-url "https://location.services.mozilla.com/v1/geolocate?key=geoclue"] @
8333 [#:wifi-submission-url "https://location.services.mozilla.com/v1/submit?key=geoclue"] @
8334 [#:submission-nick "geoclue"] @
8335 [#:applications %standard-geoclue-applications]
8336 Return a service that runs the GeoClue location service. This service
8337 provides a D-Bus interface to allow applications to request access to a
8338 user's physical location, and optionally to add information to online
8339 location databases. See
8340 @uref{https://wiki.freedesktop.org/www/Software/GeoClue/, the GeoClue
8341 web site} for more information.
8344 @deffn {Scheme Procedure} bluetooth-service [#:bluez @var{bluez}]
8345 Return a service that runs the @command{bluetoothd} daemon, which manages
8346 all the Bluetooth devices and provides a number of D-Bus interfaces.
8348 Users need to be in the @code{lp} group to access the D-Bus service.
8351 @node Database Services
8352 @subsubsection Database Services
8354 The @code{(gnu services databases)} module provides the following services.
8356 @deffn {Scheme Procedure} postgresql-service [#:postgresql postgresql] @
8357 [#:config-file] [#:data-directory ``/var/lib/postgresql/data'']
8358 Return a service that runs @var{postgresql}, the PostgreSQL database
8361 The PostgreSQL daemon loads its runtime configuration from
8362 @var{config-file} and stores the database cluster in
8363 @var{data-directory}.
8366 @deffn {Scheme Procedure} mysql-service [#:config (mysql-configuration)]
8367 Return a service that runs @command{mysqld}, the MySQL or MariaDB
8370 The optional @var{config} argument specifies the configuration for
8371 @command{mysqld}, which should be a @code{<mysql-configuraiton>} object.
8374 @deftp {Data Type} mysql-configuration
8375 Data type representing the configuration of @var{mysql-service}.
8378 @item @code{mysql} (default: @var{mariadb})
8379 Package object of the MySQL database server, can be either @var{mariadb}
8382 For MySQL, a temorary root password will be displayed at activation time.
8383 For MariaDB, the root password is empty.
8388 @subsubsection Mail Services
8390 The @code{(gnu services mail)} module provides Guix service definitions
8391 for mail services. Currently the only implemented service is Dovecot,
8392 an IMAP, POP3, and LMTP server.
8394 Guix does not yet have a mail transfer agent (MTA), although for some
8395 lightweight purposes the @code{esmtp} relay-only MTA may suffice. Help
8396 is needed to properly integrate a full MTA, such as Postfix. Patches
8399 To add an IMAP/POP3 server to a GuixSD system, add a
8400 @code{dovecot-service} to the operating system definition:
8402 @deffn {Scheme Procedure} dovecot-service [#:config (dovecot-configuration)]
8403 Return a service that runs the Dovecot IMAP/POP3/LMTP mail server.
8406 By default, Dovecot does not need much configuration; the default
8407 configuration object created by @code{(dovecot-configuration)} will
8408 suffice if your mail is delivered to @code{~/Maildir}. A self-signed
8409 certificate will be generated for TLS-protected connections, though
8410 Dovecot will also listen on cleartext ports by default. There are a
8411 number of options, though, which mail administrators might need to change,
8412 and as is the case with other services, Guix allows the system
8413 administrator to specify these parameters via a uniform Scheme interface.
8415 For example, to specify that mail is located at @code{maildir~/.mail},
8416 one would instantiate the Dovecot service like this:
8419 (dovecot-service #:config
8420 (dovecot-configuration
8421 (mail-location "maildir:~/.mail")))
8424 The available configuration parameters follow. Each parameter
8425 definition is preceded by its type; for example, @samp{string-list foo}
8426 indicates that the @code{foo} parameter should be specified as a list of
8427 strings. There is also a way to specify the configuration as a string,
8428 if you have an old @code{dovecot.conf} file that you want to port over
8429 from some other system; see the end for more details.
8431 @c The following documentation was initially generated by
8432 @c (generate-documentation) in (gnu services mail). Manually maintained
8433 @c documentation is better, so we shouldn't hesitate to edit below as
8434 @c needed. However if the change you want to make to this documentation
8435 @c can be done in an automated way, it's probably easier to change
8436 @c (generate-documentation) than to make it below and have to deal with
8437 @c the churn as dovecot updates.
8439 Available @code{dovecot-configuration} fields are:
8441 @deftypevr {@code{dovecot-configuration} parameter} package dovecot
8442 The dovecot package.
8445 @deftypevr {@code{dovecot-configuration} parameter} comma-separated-string-list listen
8446 A list of IPs or hosts where to listen for connections. @samp{*}
8447 listens on all IPv4 interfaces, @samp{::} listens on all IPv6
8448 interfaces. If you want to specify non-default ports or anything more
8449 complex, customize the address and port fields of the
8450 @samp{inet-listener} of the specific services you are interested in.
8453 @deftypevr {@code{dovecot-configuration} parameter} protocol-configuration-list protocols
8454 List of protocols we want to serve. Available protocols include
8455 @samp{imap}, @samp{pop3}, and @samp{lmtp}.
8457 Available @code{protocol-configuration} fields are:
8459 @deftypevr {@code{protocol-configuration} parameter} string name
8460 The name of the protocol.
8463 @deftypevr {@code{protocol-configuration} parameter} string auth-socket-path
8464 UNIX socket path to the master authentication server to find users.
8465 This is used by imap (for shared users) and lda.
8466 It defaults to @samp{"/var/run/dovecot/auth-userdb"}.
8469 @deftypevr {@code{protocol-configuration} parameter} space-separated-string-list mail-plugins
8470 Space separated list of plugins to load.
8473 @deftypevr {@code{protocol-configuration} parameter} non-negative-integer mail-max-userip-connections
8474 Maximum number of IMAP connections allowed for a user from each IP
8475 address. NOTE: The username is compared case-sensitively.
8476 Defaults to @samp{10}.
8481 @deftypevr {@code{dovecot-configuration} parameter} service-configuration-list services
8482 List of services to enable. Available services include @samp{imap},
8483 @samp{imap-login}, @samp{pop3}, @samp{pop3-login}, @samp{auth}, and
8486 Available @code{service-configuration} fields are:
8488 @deftypevr {@code{service-configuration} parameter} string kind
8489 The service kind. Valid values include @code{director},
8490 @code{imap-login}, @code{pop3-login}, @code{lmtp}, @code{imap},
8491 @code{pop3}, @code{auth}, @code{auth-worker}, @code{dict},
8492 @code{tcpwrap}, @code{quota-warning}, or anything else.
8495 @deftypevr {@code{service-configuration} parameter} listener-configuration-list listeners
8496 Listeners for the service. A listener is either a
8497 @code{unix-listener-configuration}, a @code{fifo-listener-configuration}, or
8498 an @code{inet-listener-configuration}.
8499 Defaults to @samp{()}.
8501 Available @code{unix-listener-configuration} fields are:
8503 @deftypevr {@code{unix-listener-configuration} parameter} file-name path
8504 The file name on which to listen.
8507 @deftypevr {@code{unix-listener-configuration} parameter} string mode
8508 The access mode for the socket.
8509 Defaults to @samp{"0600"}.
8512 @deftypevr {@code{unix-listener-configuration} parameter} string user
8513 The user to own the socket.
8514 Defaults to @samp{""}.
8517 @deftypevr {@code{unix-listener-configuration} parameter} string group
8518 The group to own the socket.
8519 Defaults to @samp{""}.
8523 Available @code{fifo-listener-configuration} fields are:
8525 @deftypevr {@code{fifo-listener-configuration} parameter} file-name path
8526 The file name on which to listen.
8529 @deftypevr {@code{fifo-listener-configuration} parameter} string mode
8530 The access mode for the socket.
8531 Defaults to @samp{"0600"}.
8534 @deftypevr {@code{fifo-listener-configuration} parameter} string user
8535 The user to own the socket.
8536 Defaults to @samp{""}.
8539 @deftypevr {@code{fifo-listener-configuration} parameter} string group
8540 The group to own the socket.
8541 Defaults to @samp{""}.
8545 Available @code{inet-listener-configuration} fields are:
8547 @deftypevr {@code{inet-listener-configuration} parameter} string protocol
8548 The protocol to listen for.
8551 @deftypevr {@code{inet-listener-configuration} parameter} string address
8552 The address on which to listen, or empty for all addresses.
8553 Defaults to @samp{""}.
8556 @deftypevr {@code{inet-listener-configuration} parameter} non-negative-integer port
8557 The port on which to listen.
8560 @deftypevr {@code{inet-listener-configuration} parameter} boolean ssl?
8561 Whether to use SSL for this service; @samp{yes}, @samp{no}, or
8563 Defaults to @samp{#t}.
8568 @deftypevr {@code{service-configuration} parameter} non-negative-integer service-count
8569 Number of connections to handle before starting a new process.
8570 Typically the only useful values are 0 (unlimited) or 1. 1 is more
8571 secure, but 0 is faster. <doc/wiki/LoginProcess.txt>.
8572 Defaults to @samp{1}.
8575 @deftypevr {@code{service-configuration} parameter} non-negative-integer process-min-avail
8576 Number of processes to always keep waiting for more connections.
8577 Defaults to @samp{0}.
8580 @deftypevr {@code{service-configuration} parameter} non-negative-integer vsz-limit
8581 If you set @samp{service-count 0}, you probably need to grow
8583 Defaults to @samp{256000000}.
8588 @deftypevr {@code{dovecot-configuration} parameter} dict-configuration dict
8589 Dict configuration, as created by the @code{dict-configuration}
8592 Available @code{dict-configuration} fields are:
8594 @deftypevr {@code{dict-configuration} parameter} free-form-fields entries
8595 A list of key-value pairs that this dict should hold.
8596 Defaults to @samp{()}.
8601 @deftypevr {@code{dovecot-configuration} parameter} passdb-configuration-list passdbs
8602 A list of passdb configurations, each one created by the
8603 @code{passdb-configuration} constructor.
8605 Available @code{passdb-configuration} fields are:
8607 @deftypevr {@code{passdb-configuration} parameter} string driver
8608 The driver that the passdb should use. Valid values include
8609 @samp{pam}, @samp{passwd}, @samp{shadow}, @samp{bsdauth}, and
8611 Defaults to @samp{"pam"}.
8614 @deftypevr {@code{passdb-configuration} parameter} free-form-args args
8615 A list of key-value args to the passdb driver.
8616 Defaults to @samp{()}.
8621 @deftypevr {@code{dovecot-configuration} parameter} userdb-configuration-list userdbs
8622 List of userdb configurations, each one created by the
8623 @code{userdb-configuration} constructor.
8625 Available @code{userdb-configuration} fields are:
8627 @deftypevr {@code{userdb-configuration} parameter} string driver
8628 The driver that the userdb should use. Valid values include
8629 @samp{passwd} and @samp{static}.
8630 Defaults to @samp{"passwd"}.
8633 @deftypevr {@code{userdb-configuration} parameter} free-form-args args
8634 A list of key-value args to the userdb driver.
8635 Defaults to @samp{()}.
8638 @deftypevr {@code{userdb-configuration} parameter} free-form-args override-fields
8639 Override fields from passwd.
8640 Defaults to @samp{()}.
8645 @deftypevr {@code{dovecot-configuration} parameter} plugin-configuration plugin-configuration
8646 Plug-in configuration, created by the @code{plugin-configuration}
8650 @deftypevr {@code{dovecot-configuration} parameter} list-of-namespace-configuration namespaces
8651 List of namespaces. Each item in the list is created by the
8652 @code{namespace-configuration} constructor.
8654 Available @code{namespace-configuration} fields are:
8656 @deftypevr {@code{namespace-configuration} parameter} string name
8657 Name for this namespace.
8660 @deftypevr {@code{namespace-configuration} parameter} string type
8661 Namespace type: @samp{private}, @samp{shared} or @samp{public}.
8662 Defaults to @samp{"private"}.
8665 @deftypevr {@code{namespace-configuration} parameter} string separator
8666 Hierarchy separator to use. You should use the same separator for
8667 all namespaces or some clients get confused. @samp{/} is usually a good
8668 one. The default however depends on the underlying mail storage
8670 Defaults to @samp{""}.
8673 @deftypevr {@code{namespace-configuration} parameter} string prefix
8674 Prefix required to access this namespace. This needs to be
8675 different for all namespaces. For example @samp{Public/}.
8676 Defaults to @samp{""}.
8679 @deftypevr {@code{namespace-configuration} parameter} string location
8680 Physical location of the mailbox. This is in the same format as
8681 mail_location, which is also the default for it.
8682 Defaults to @samp{""}.
8685 @deftypevr {@code{namespace-configuration} parameter} boolean inbox?
8686 There can be only one INBOX, and this setting defines which
8688 Defaults to @samp{#f}.
8691 @deftypevr {@code{namespace-configuration} parameter} boolean hidden?
8692 If namespace is hidden, it's not advertised to clients via NAMESPACE
8693 extension. You'll most likely also want to set @samp{list? #f}. This is mostly
8694 useful when converting from another server with different namespaces
8695 which you want to deprecate but still keep working. For example you can
8696 create hidden namespaces with prefixes @samp{~/mail/}, @samp{~%u/mail/}
8698 Defaults to @samp{#f}.
8701 @deftypevr {@code{namespace-configuration} parameter} boolean list?
8702 Show the mailboxes under this namespace with the LIST command. This
8703 makes the namespace visible for clients that do not support the NAMESPACE
8704 extension. The special @code{children} value lists child mailboxes, but
8705 hides the namespace prefix.
8706 Defaults to @samp{#t}.
8709 @deftypevr {@code{namespace-configuration} parameter} boolean subscriptions?
8710 Namespace handles its own subscriptions. If set to @code{#f}, the
8711 parent namespace handles them. The empty prefix should always have this
8713 Defaults to @samp{#t}.
8716 @deftypevr {@code{namespace-configuration} parameter} mailbox-configuration-list mailboxes
8717 List of predefined mailboxes in this namespace.
8718 Defaults to @samp{()}.
8720 Available @code{mailbox-configuration} fields are:
8722 @deftypevr {@code{mailbox-configuration} parameter} string name
8723 Name for this mailbox.
8726 @deftypevr {@code{mailbox-configuration} parameter} string auto
8727 @samp{create} will automatically create this mailbox.
8728 @samp{subscribe} will both create and subscribe to the mailbox.
8729 Defaults to @samp{"no"}.
8732 @deftypevr {@code{mailbox-configuration} parameter} space-separated-string-list special-use
8733 List of IMAP @code{SPECIAL-USE} attributes as specified by RFC 6154.
8734 Valid values are @code{\All}, @code{\Archive}, @code{\Drafts},
8735 @code{\Flagged}, @code{\Junk}, @code{\Sent}, and @code{\Trash}.
8736 Defaults to @samp{()}.
8743 @deftypevr {@code{dovecot-configuration} parameter} file-name base-dir
8744 Base directory where to store runtime data.
8745 Defaults to @samp{"/var/run/dovecot/"}.
8748 @deftypevr {@code{dovecot-configuration} parameter} string login-greeting
8749 Greeting message for clients.
8750 Defaults to @samp{"Dovecot ready."}.
8753 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-trusted-networks
8754 List of trusted network ranges. Connections from these IPs are
8755 allowed to override their IP addresses and ports (for logging and for
8756 authentication checks). @samp{disable-plaintext-auth} is also ignored
8757 for these networks. Typically you would specify your IMAP proxy servers
8759 Defaults to @samp{()}.
8762 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-access-sockets
8763 List of login access check sockets (e.g. tcpwrap).
8764 Defaults to @samp{()}.
8767 @deftypevr {@code{dovecot-configuration} parameter} boolean verbose-proctitle?
8768 Show more verbose process titles (in ps). Currently shows user name
8769 and IP address. Useful for seeing who is actually using the IMAP
8770 processes (e.g. shared mailboxes or if the same uid is used for multiple
8772 Defaults to @samp{#f}.
8775 @deftypevr {@code{dovecot-configuration} parameter} boolean shutdown-clients?
8776 Should all processes be killed when Dovecot master process shuts down.
8777 Setting this to @code{#f} means that Dovecot can be upgraded without
8778 forcing existing client connections to close (although that could also
8779 be a problem if the upgrade is e.g. due to a security fix).
8780 Defaults to @samp{#t}.
8783 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer doveadm-worker-count
8784 If non-zero, run mail commands via this many connections to doveadm
8785 server, instead of running them directly in the same process.
8786 Defaults to @samp{0}.
8789 @deftypevr {@code{dovecot-configuration} parameter} string doveadm-socket-path
8790 UNIX socket or host:port used for connecting to doveadm server.
8791 Defaults to @samp{"doveadm-server"}.
8794 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list import-environment
8795 List of environment variables that are preserved on Dovecot startup
8796 and passed down to all of its child processes. You can also give
8797 key=value pairs to always set specific settings.
8800 @deftypevr {@code{dovecot-configuration} parameter} boolean disable-plaintext-auth?
8801 Disable LOGIN command and all other plaintext authentications unless
8802 SSL/TLS is used (LOGINDISABLED capability). Note that if the remote IP
8803 matches the local IP (i.e. you're connecting from the same computer),
8804 the connection is considered secure and plaintext authentication is
8805 allowed. See also ssl=required setting.
8806 Defaults to @samp{#t}.
8809 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer auth-cache-size
8810 Authentication cache size (e.g. @samp{#e10e6}). 0 means it's disabled.
8811 Note that bsdauth, PAM and vpopmail require @samp{cache-key} to be set
8812 for caching to be used.
8813 Defaults to @samp{0}.
8816 @deftypevr {@code{dovecot-configuration} parameter} string auth-cache-ttl
8817 Time to live for cached data. After TTL expires the cached record
8818 is no longer used, *except* if the main database lookup returns internal
8819 failure. We also try to handle password changes automatically: If
8820 user's previous authentication was successful, but this one wasn't, the
8821 cache isn't used. For now this works only with plaintext
8823 Defaults to @samp{"1 hour"}.
8826 @deftypevr {@code{dovecot-configuration} parameter} string auth-cache-negative-ttl
8827 TTL for negative hits (user not found, password mismatch).
8828 0 disables caching them completely.
8829 Defaults to @samp{"1 hour"}.
8832 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list auth-realms
8833 List of realms for SASL authentication mechanisms that need them.
8834 You can leave it empty if you don't want to support multiple realms.
8835 Many clients simply use the first one listed here, so keep the default
8837 Defaults to @samp{()}.
8840 @deftypevr {@code{dovecot-configuration} parameter} string auth-default-realm
8841 Default realm/domain to use if none was specified. This is used for
8842 both SASL realms and appending @@domain to username in plaintext
8844 Defaults to @samp{""}.
8847 @deftypevr {@code{dovecot-configuration} parameter} string auth-username-chars
8848 List of allowed characters in username. If the user-given username
8849 contains a character not listed in here, the login automatically fails.
8850 This is just an extra check to make sure user can't exploit any
8851 potential quote escaping vulnerabilities with SQL/LDAP databases. If
8852 you want to allow all characters, set this value to empty.
8853 Defaults to @samp{"abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ01234567890.-_@@"}.
8856 @deftypevr {@code{dovecot-configuration} parameter} string auth-username-translation
8857 Username character translations before it's looked up from
8858 databases. The value contains series of from -> to characters. For
8859 example @samp{#@@/@@} means that @samp{#} and @samp{/} characters are
8860 translated to @samp{@@}.
8861 Defaults to @samp{""}.
8864 @deftypevr {@code{dovecot-configuration} parameter} string auth-username-format
8865 Username formatting before it's looked up from databases. You can
8866 use the standard variables here, e.g. %Lu would lowercase the username,
8867 %n would drop away the domain if it was given, or @samp{%n-AT-%d} would
8868 change the @samp{@@} into @samp{-AT-}. This translation is done after
8869 @samp{auth-username-translation} changes.
8870 Defaults to @samp{"%Lu"}.
8873 @deftypevr {@code{dovecot-configuration} parameter} string auth-master-user-separator
8874 If you want to allow master users to log in by specifying the master
8875 username within the normal username string (i.e. not using SASL
8876 mechanism's support for it), you can specify the separator character
8877 here. The format is then <username><separator><master username>.
8878 UW-IMAP uses @samp{*} as the separator, so that could be a good
8880 Defaults to @samp{""}.
8883 @deftypevr {@code{dovecot-configuration} parameter} string auth-anonymous-username
8884 Username to use for users logging in with ANONYMOUS SASL
8886 Defaults to @samp{"anonymous"}.
8889 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer auth-worker-max-count
8890 Maximum number of dovecot-auth worker processes. They're used to
8891 execute blocking passdb and userdb queries (e.g. MySQL and PAM).
8892 They're automatically created and destroyed as needed.
8893 Defaults to @samp{30}.
8896 @deftypevr {@code{dovecot-configuration} parameter} string auth-gssapi-hostname
8897 Host name to use in GSSAPI principal names. The default is to use
8898 the name returned by gethostname(). Use @samp{$ALL} (with quotes) to
8899 allow all keytab entries.
8900 Defaults to @samp{""}.
8903 @deftypevr {@code{dovecot-configuration} parameter} string auth-krb5-keytab
8904 Kerberos keytab to use for the GSSAPI mechanism. Will use the
8905 system default (usually /etc/krb5.keytab) if not specified. You may
8906 need to change the auth service to run as root to be able to read this
8908 Defaults to @samp{""}.
8911 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-use-winbind?
8912 Do NTLM and GSS-SPNEGO authentication using Samba's winbind daemon
8913 and @samp{ntlm-auth} helper.
8914 <doc/wiki/Authentication/Mechanisms/Winbind.txt>.
8915 Defaults to @samp{#f}.
8918 @deftypevr {@code{dovecot-configuration} parameter} file-name auth-winbind-helper-path
8919 Path for Samba's @samp{ntlm-auth} helper binary.
8920 Defaults to @samp{"/usr/bin/ntlm_auth"}.
8923 @deftypevr {@code{dovecot-configuration} parameter} string auth-failure-delay
8924 Time to delay before replying to failed authentications.
8925 Defaults to @samp{"2 secs"}.
8928 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-ssl-require-client-cert?
8929 Require a valid SSL client certificate or the authentication
8931 Defaults to @samp{#f}.
8934 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-ssl-username-from-cert?
8935 Take the username from client's SSL certificate, using
8936 @code{X509_NAME_get_text_by_NID()} which returns the subject's DN's
8938 Defaults to @samp{#f}.
8941 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list auth-mechanisms
8942 List of wanted authentication mechanisms. Supported mechanisms are:
8943 @samp{plain}, @samp{login}, @samp{digest-md5}, @samp{cram-md5},
8944 @samp{ntlm}, @samp{rpa}, @samp{apop}, @samp{anonymous}, @samp{gssapi},
8945 @samp{otp}, @samp{skey}, and @samp{gss-spnego}. NOTE: See also
8946 @samp{disable-plaintext-auth} setting.
8949 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list director-servers
8950 List of IPs or hostnames to all director servers, including ourself.
8951 Ports can be specified as ip:port. The default port is the same as what
8952 director service's @samp{inet-listener} is using.
8953 Defaults to @samp{()}.
8956 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list director-mail-servers
8957 List of IPs or hostnames to all backend mail servers. Ranges are
8958 allowed too, like 10.0.0.10-10.0.0.30.
8959 Defaults to @samp{()}.
8962 @deftypevr {@code{dovecot-configuration} parameter} string director-user-expire
8963 How long to redirect users to a specific server after it no longer
8964 has any connections.
8965 Defaults to @samp{"15 min"}.
8968 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer director-doveadm-port
8969 TCP/IP port that accepts doveadm connections (instead of director
8970 connections) If you enable this, you'll also need to add
8971 @samp{inet-listener} for the port.
8972 Defaults to @samp{0}.
8975 @deftypevr {@code{dovecot-configuration} parameter} string director-username-hash
8976 How the username is translated before being hashed. Useful values
8977 include %Ln if user can log in with or without @@domain, %Ld if mailboxes
8978 are shared within domain.
8979 Defaults to @samp{"%Lu"}.
8982 @deftypevr {@code{dovecot-configuration} parameter} string log-path
8983 Log file to use for error messages. @samp{syslog} logs to syslog,
8984 @samp{/dev/stderr} logs to stderr.
8985 Defaults to @samp{"syslog"}.
8988 @deftypevr {@code{dovecot-configuration} parameter} string info-log-path
8989 Log file to use for informational messages. Defaults to
8991 Defaults to @samp{""}.
8994 @deftypevr {@code{dovecot-configuration} parameter} string debug-log-path
8995 Log file to use for debug messages. Defaults to
8996 @samp{info-log-path}.
8997 Defaults to @samp{""}.
9000 @deftypevr {@code{dovecot-configuration} parameter} string syslog-facility
9001 Syslog facility to use if you're logging to syslog. Usually if you
9002 don't want to use @samp{mail}, you'll use local0..local7. Also other
9003 standard facilities are supported.
9004 Defaults to @samp{"mail"}.
9007 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-verbose?
9008 Log unsuccessful authentication attempts and the reasons why they
9010 Defaults to @samp{#f}.
9013 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-verbose-passwords?
9014 In case of password mismatches, log the attempted password. Valid
9015 values are no, plain and sha1. sha1 can be useful for detecting brute
9016 force password attempts vs. user simply trying the same password over
9017 and over again. You can also truncate the value to n chars by appending
9019 Defaults to @samp{#f}.
9022 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-debug?
9023 Even more verbose logging for debugging purposes. Shows for example
9025 Defaults to @samp{#f}.
9028 @deftypevr {@code{dovecot-configuration} parameter} boolean auth-debug-passwords?
9029 In case of password mismatches, log the passwords and used scheme so
9030 the problem can be debugged. Enabling this also enables
9032 Defaults to @samp{#f}.
9035 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-debug?
9036 Enable mail process debugging. This can help you figure out why
9037 Dovecot isn't finding your mails.
9038 Defaults to @samp{#f}.
9041 @deftypevr {@code{dovecot-configuration} parameter} boolean verbose-ssl?
9042 Show protocol level SSL errors.
9043 Defaults to @samp{#f}.
9046 @deftypevr {@code{dovecot-configuration} parameter} string log-timestamp
9047 Prefix for each line written to log file. % codes are in
9049 Defaults to @samp{"\"%b %d %H:%M:%S \""}.
9052 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list login-log-format-elements
9053 List of elements we want to log. The elements which have a
9054 non-empty variable value are joined together to form a comma-separated
9058 @deftypevr {@code{dovecot-configuration} parameter} string login-log-format
9059 Login log format. %s contains @samp{login-log-format-elements}
9060 string, %$ contains the data we want to log.
9061 Defaults to @samp{"%$: %s"}.
9064 @deftypevr {@code{dovecot-configuration} parameter} string mail-log-prefix
9065 Log prefix for mail processes. See doc/wiki/Variables.txt for list
9066 of possible variables you can use.
9067 Defaults to @samp{"\"%s(%u): \""}.
9070 @deftypevr {@code{dovecot-configuration} parameter} string deliver-log-format
9071 Format to use for logging mail deliveries. You can use variables:
9074 Delivery status message (e.g. @samp{saved to INBOX})
9086 Defaults to @samp{"msgid=%m: %$"}.
9089 @deftypevr {@code{dovecot-configuration} parameter} string mail-location
9090 Location for users' mailboxes. The default is empty, which means
9091 that Dovecot tries to find the mailboxes automatically. This won't work
9092 if the user doesn't yet have any mail, so you should explicitly tell
9093 Dovecot the full location.
9095 If you're using mbox, giving a path to the INBOX
9096 file (e.g. /var/mail/%u) isn't enough. You'll also need to tell Dovecot
9097 where the other mailboxes are kept. This is called the "root mail
9098 directory", and it must be the first path given in the
9099 @samp{mail-location} setting.
9101 There are a few special variables you can use, eg.:
9107 user part in user@@domain, same as %u if there's no domain
9109 domain part in user@@domain, empty if there's no domain
9114 See doc/wiki/Variables.txt for full list. Some examples:
9116 @item maildir:~/Maildir
9117 @item mbox:~/mail:INBOX=/var/mail/%u
9118 @item mbox:/var/mail/%d/%1n/%n:INDEX=/var/indexes/%d/%1n/%
9120 Defaults to @samp{""}.
9123 @deftypevr {@code{dovecot-configuration} parameter} string mail-uid
9124 System user and group used to access mails. If you use multiple,
9125 userdb can override these by returning uid or gid fields. You can use
9126 either numbers or names. <doc/wiki/UserIds.txt>.
9127 Defaults to @samp{""}.
9130 @deftypevr {@code{dovecot-configuration} parameter} string mail-gid
9132 Defaults to @samp{""}.
9135 @deftypevr {@code{dovecot-configuration} parameter} string mail-privileged-group
9136 Group to enable temporarily for privileged operations. Currently
9137 this is used only with INBOX when either its initial creation or
9138 dotlocking fails. Typically this is set to "mail" to give access to
9140 Defaults to @samp{""}.
9143 @deftypevr {@code{dovecot-configuration} parameter} string mail-access-groups
9144 Grant access to these supplementary groups for mail processes.
9145 Typically these are used to set up access to shared mailboxes. Note
9146 that it may be dangerous to set these if users can create
9147 symlinks (e.g. if "mail" group is set here, ln -s /var/mail ~/mail/var
9148 could allow a user to delete others' mailboxes, or ln -s
9149 /secret/shared/box ~/mail/mybox would allow reading it).
9150 Defaults to @samp{""}.
9153 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-full-filesystem-access?
9154 Allow full filesystem access to clients. There's no access checks
9155 other than what the operating system does for the active UID/GID. It
9156 works with both maildir and mboxes, allowing you to prefix mailboxes
9157 names with e.g. /path/ or ~user/.
9158 Defaults to @samp{#f}.
9161 @deftypevr {@code{dovecot-configuration} parameter} boolean mmap-disable?
9162 Don't use mmap() at all. This is required if you store indexes to
9163 shared filesystems (NFS or clustered filesystem).
9164 Defaults to @samp{#f}.
9167 @deftypevr {@code{dovecot-configuration} parameter} boolean dotlock-use-excl?
9168 Rely on @samp{O_EXCL} to work when creating dotlock files. NFS
9169 supports @samp{O_EXCL} since version 3, so this should be safe to use
9170 nowadays by default.
9171 Defaults to @samp{#t}.
9174 @deftypevr {@code{dovecot-configuration} parameter} string mail-fsync
9175 When to use fsync() or fdatasync() calls:
9178 Whenever necessary to avoid losing important data
9180 Useful with e.g. NFS when write()s are delayed
9182 Never use it (best performance, but crashes can lose data).
9184 Defaults to @samp{"optimized"}.
9187 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-nfs-storage?
9188 Mail storage exists in NFS. Set this to yes to make Dovecot flush
9189 NFS caches whenever needed. If you're using only a single mail server
9191 Defaults to @samp{#f}.
9194 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-nfs-index?
9195 Mail index files also exist in NFS. Setting this to yes requires
9196 @samp{mmap-disable? #t} and @samp{fsync-disable? #f}.
9197 Defaults to @samp{#f}.
9200 @deftypevr {@code{dovecot-configuration} parameter} string lock-method
9201 Locking method for index files. Alternatives are fcntl, flock and
9202 dotlock. Dotlocking uses some tricks which may create more disk I/O
9203 than other locking methods. NFS users: flock doesn't work, remember to
9204 change @samp{mmap-disable}.
9205 Defaults to @samp{"fcntl"}.
9208 @deftypevr {@code{dovecot-configuration} parameter} file-name mail-temp-dir
9209 Directory in which LDA/LMTP temporarily stores incoming mails >128
9211 Defaults to @samp{"/tmp"}.
9214 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer first-valid-uid
9215 Valid UID range for users. This is mostly to make sure that users can't
9216 log in as daemons or other system users. Note that denying root logins is
9217 hardcoded to dovecot binary and can't be done even if @samp{first-valid-uid}
9219 Defaults to @samp{500}.
9222 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer last-valid-uid
9224 Defaults to @samp{0}.
9227 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer first-valid-gid
9228 Valid GID range for users. Users having non-valid GID as primary group ID
9229 aren't allowed to log in. If user belongs to supplementary groups with
9230 non-valid GIDs, those groups are not set.
9231 Defaults to @samp{1}.
9234 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer last-valid-gid
9236 Defaults to @samp{0}.
9239 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-max-keyword-length
9240 Maximum allowed length for mail keyword name. It's only forced when
9241 trying to create new keywords.
9242 Defaults to @samp{50}.
9245 @deftypevr {@code{dovecot-configuration} parameter} colon-separated-file-name-list valid-chroot-dirs
9246 List of directories under which chrooting is allowed for mail
9247 processes (i.e. /var/mail will allow chrooting to /var/mail/foo/bar
9248 too). This setting doesn't affect @samp{login-chroot}
9249 @samp{mail-chroot} or auth chroot settings. If this setting is empty,
9250 "/./" in home dirs are ignored. WARNING: Never add directories here
9251 which local users can modify, that may lead to root exploit. Usually
9252 this should be done only if you don't allow shell access for users.
9253 <doc/wiki/Chrooting.txt>.
9254 Defaults to @samp{()}.
9257 @deftypevr {@code{dovecot-configuration} parameter} string mail-chroot
9258 Default chroot directory for mail processes. This can be overridden
9259 for specific users in user database by giving /./ in user's home
9260 directory (e.g. /home/./user chroots into /home). Note that usually
9261 there is no real need to do chrooting, Dovecot doesn't allow users to
9262 access files outside their mail directory anyway. If your home
9263 directories are prefixed with the chroot directory, append "/." to
9264 @samp{mail-chroot}. <doc/wiki/Chrooting.txt>.
9265 Defaults to @samp{""}.
9268 @deftypevr {@code{dovecot-configuration} parameter} file-name auth-socket-path
9269 UNIX socket path to master authentication server to find users.
9270 This is used by imap (for shared users) and lda.
9271 Defaults to @samp{"/var/run/dovecot/auth-userdb"}.
9274 @deftypevr {@code{dovecot-configuration} parameter} file-name mail-plugin-dir
9275 Directory where to look up mail plugins.
9276 Defaults to @samp{"/usr/lib/dovecot"}.
9279 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mail-plugins
9280 List of plugins to load for all services. Plugins specific to IMAP,
9281 LDA, etc. are added to this list in their own .conf files.
9282 Defaults to @samp{()}.
9285 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-cache-min-mail-count
9286 The minimum number of mails in a mailbox before updates are done to
9287 cache file. This allows optimizing Dovecot's behavior to do less disk
9288 writes at the cost of more disk reads.
9289 Defaults to @samp{0}.
9292 @deftypevr {@code{dovecot-configuration} parameter} string mailbox-idle-check-interval
9293 When IDLE command is running, mailbox is checked once in a while to
9294 see if there are any new mails or other changes. This setting defines
9295 the minimum time to wait between those checks. Dovecot can also use
9296 dnotify, inotify and kqueue to find out immediately when changes
9298 Defaults to @samp{"30 secs"}.
9301 @deftypevr {@code{dovecot-configuration} parameter} boolean mail-save-crlf?
9302 Save mails with CR+LF instead of plain LF. This makes sending those
9303 mails take less CPU, especially with sendfile() syscall with Linux and
9304 FreeBSD. But it also creates a bit more disk I/O which may just make it
9305 slower. Also note that if other software reads the mboxes/maildirs,
9306 they may handle the extra CRs wrong and cause problems.
9307 Defaults to @samp{#f}.
9310 @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-stat-dirs?
9311 By default LIST command returns all entries in maildir beginning
9312 with a dot. Enabling this option makes Dovecot return only entries
9313 which are directories. This is done by stat()ing each entry, so it
9314 causes more disk I/O.
9315 (For systems setting struct @samp{dirent->d_type} this check is free
9316 and it's done always regardless of this setting).
9317 Defaults to @samp{#f}.
9320 @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-copy-with-hardlinks?
9321 When copying a message, do it with hard links whenever possible.
9322 This makes the performance much better, and it's unlikely to have any
9324 Defaults to @samp{#t}.
9327 @deftypevr {@code{dovecot-configuration} parameter} boolean maildir-very-dirty-syncs?
9328 Assume Dovecot is the only MUA accessing Maildir: Scan cur/
9329 directory only when its mtime changes unexpectedly or when we can't find
9331 Defaults to @samp{#f}.
9334 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mbox-read-locks
9335 Which locking methods to use for locking mbox. There are four
9340 Create <mailbox>.lock file. This is the oldest and most NFS-safe
9341 solution. If you want to use /var/mail/ like directory, the users will
9342 need write access to that directory.
9344 Same as dotlock, but if it fails because of permissions or because there
9345 isn't enough disk space, just skip it.
9347 Use this if possible. Works with NFS too if lockd is used.
9349 May not exist in all systems. Doesn't work with NFS.
9351 May not exist in all systems. Doesn't work with NFS.
9354 You can use multiple locking methods; if you do the order they're declared
9355 in is important to avoid deadlocks if other MTAs/MUAs are using multiple
9356 locking methods as well. Some operating systems don't allow using some of
9357 them simultaneously.
9360 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list mbox-write-locks
9364 @deftypevr {@code{dovecot-configuration} parameter} string mbox-lock-timeout
9365 Maximum time to wait for lock (all of them) before aborting.
9366 Defaults to @samp{"5 mins"}.
9369 @deftypevr {@code{dovecot-configuration} parameter} string mbox-dotlock-change-timeout
9370 If dotlock exists but the mailbox isn't modified in any way,
9371 override the lock file after this much time.
9372 Defaults to @samp{"2 mins"}.
9375 @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-dirty-syncs?
9376 When mbox changes unexpectedly we have to fully read it to find out
9377 what changed. If the mbox is large this can take a long time. Since
9378 the change is usually just a newly appended mail, it'd be faster to
9379 simply read the new mails. If this setting is enabled, Dovecot does
9380 this but still safely fallbacks to re-reading the whole mbox file
9381 whenever something in mbox isn't how it's expected to be. The only real
9382 downside to this setting is that if some other MUA changes message
9383 flags, Dovecot doesn't notice it immediately. Note that a full sync is
9384 done with SELECT, EXAMINE, EXPUNGE and CHECK commands.
9385 Defaults to @samp{#t}.
9388 @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-very-dirty-syncs?
9389 Like @samp{mbox-dirty-syncs}, but don't do full syncs even with SELECT,
9390 EXAMINE, EXPUNGE or CHECK commands. If this is set,
9391 @samp{mbox-dirty-syncs} is ignored.
9392 Defaults to @samp{#f}.
9395 @deftypevr {@code{dovecot-configuration} parameter} boolean mbox-lazy-writes?
9396 Delay writing mbox headers until doing a full write sync (EXPUNGE
9397 and CHECK commands and when closing the mailbox). This is especially
9398 useful for POP3 where clients often delete all mails. The downside is
9399 that our changes aren't immediately visible to other MUAs.
9400 Defaults to @samp{#t}.
9403 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mbox-min-index-size
9404 If mbox size is smaller than this (e.g. 100k), don't write index
9405 files. If an index file already exists it's still read, just not
9407 Defaults to @samp{0}.
9410 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mdbox-rotate-size
9411 Maximum dbox file size until it's rotated.
9412 Defaults to @samp{2000000}.
9415 @deftypevr {@code{dovecot-configuration} parameter} string mdbox-rotate-interval
9416 Maximum dbox file age until it's rotated. Typically in days. Day
9417 begins from midnight, so 1d = today, 2d = yesterday, etc. 0 = check
9419 Defaults to @samp{"1d"}.
9422 @deftypevr {@code{dovecot-configuration} parameter} boolean mdbox-preallocate-space?
9423 When creating new mdbox files, immediately preallocate their size to
9424 @samp{mdbox-rotate-size}. This setting currently works only in Linux
9425 with some filesystems (ext4, xfs).
9426 Defaults to @samp{#f}.
9429 @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-dir
9430 sdbox and mdbox support saving mail attachments to external files,
9431 which also allows single instance storage for them. Other backends
9432 don't support this for now.
9434 WARNING: This feature hasn't been tested much yet. Use at your own risk.
9436 Directory root where to store mail attachments. Disabled, if empty.
9437 Defaults to @samp{""}.
9440 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer mail-attachment-min-size
9441 Attachments smaller than this aren't saved externally. It's also
9442 possible to write a plugin to disable saving specific attachments
9444 Defaults to @samp{128000}.
9447 @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-fs
9448 Filesystem backend to use for saving attachments:
9451 No SiS done by Dovecot (but this might help FS's own deduplication)
9453 SiS with immediate byte-by-byte comparison during saving
9454 @item sis-queue posix
9455 SiS with delayed comparison and deduplication.
9457 Defaults to @samp{"sis posix"}.
9460 @deftypevr {@code{dovecot-configuration} parameter} string mail-attachment-hash
9461 Hash format to use in attachment filenames. You can add any text and
9462 variables: @code{%@{md4@}}, @code{%@{md5@}}, @code{%@{sha1@}},
9463 @code{%@{sha256@}}, @code{%@{sha512@}}, @code{%@{size@}}. Variables can be
9464 truncated, e.g. @code{%@{sha256:80@}} returns only first 80 bits.
9465 Defaults to @samp{"%@{sha1@}"}.
9468 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-process-limit
9470 Defaults to @samp{100}.
9473 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-client-limit
9475 Defaults to @samp{1000}.
9478 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer default-vsz-limit
9479 Default VSZ (virtual memory size) limit for service processes.
9480 This is mainly intended to catch and kill processes that leak memory
9481 before they eat up everything.
9482 Defaults to @samp{256000000}.
9485 @deftypevr {@code{dovecot-configuration} parameter} string default-login-user
9486 Login user is internally used by login processes. This is the most
9487 untrusted user in Dovecot system. It shouldn't have access to anything
9489 Defaults to @samp{"dovenull"}.
9492 @deftypevr {@code{dovecot-configuration} parameter} string default-internal-user
9493 Internal user is used by unprivileged processes. It should be
9494 separate from login user, so that login processes can't disturb other
9496 Defaults to @samp{"dovecot"}.
9499 @deftypevr {@code{dovecot-configuration} parameter} string ssl?
9500 SSL/TLS support: yes, no, required. <doc/wiki/SSL.txt>.
9501 Defaults to @samp{"required"}.
9504 @deftypevr {@code{dovecot-configuration} parameter} string ssl-cert
9505 PEM encoded X.509 SSL/TLS certificate (public key).
9506 Defaults to @samp{"</etc/dovecot/default.pem"}.
9509 @deftypevr {@code{dovecot-configuration} parameter} string ssl-key
9510 PEM encoded SSL/TLS private key. The key is opened before
9511 dropping root privileges, so keep the key file unreadable by anyone but
9513 Defaults to @samp{"</etc/dovecot/private/default.pem"}.
9516 @deftypevr {@code{dovecot-configuration} parameter} string ssl-key-password
9517 If key file is password protected, give the password here.
9518 Alternatively give it when starting dovecot with -p parameter. Since
9519 this file is often world-readable, you may want to place this setting
9520 instead to a different.
9521 Defaults to @samp{""}.
9524 @deftypevr {@code{dovecot-configuration} parameter} string ssl-ca
9525 PEM encoded trusted certificate authority. Set this only if you
9526 intend to use @samp{ssl-verify-client-cert? #t}. The file should
9527 contain the CA certificate(s) followed by the matching
9528 CRL(s). (e.g. @samp{ssl-ca </etc/ssl/certs/ca.pem}).
9529 Defaults to @samp{""}.
9532 @deftypevr {@code{dovecot-configuration} parameter} boolean ssl-require-crl?
9533 Require that CRL check succeeds for client certificates.
9534 Defaults to @samp{#t}.
9537 @deftypevr {@code{dovecot-configuration} parameter} boolean ssl-verify-client-cert?
9538 Request client to send a certificate. If you also want to require
9539 it, set @samp{auth-ssl-require-client-cert? #t} in auth section.
9540 Defaults to @samp{#f}.
9543 @deftypevr {@code{dovecot-configuration} parameter} string ssl-cert-username-field
9544 Which field from certificate to use for username. commonName and
9545 x500UniqueIdentifier are the usual choices. You'll also need to set
9546 @samp{auth-ssl-username-from-cert? #t}.
9547 Defaults to @samp{"commonName"}.
9550 @deftypevr {@code{dovecot-configuration} parameter} hours ssl-parameters-regenerate
9551 How often to regenerate the SSL parameters file. Generation is
9552 quite CPU intensive operation. The value is in hours, 0 disables
9553 regeneration entirely.
9554 Defaults to @samp{168}.
9557 @deftypevr {@code{dovecot-configuration} parameter} string ssl-protocols
9558 SSL protocols to use.
9559 Defaults to @samp{"!SSLv2"}.
9562 @deftypevr {@code{dovecot-configuration} parameter} string ssl-cipher-list
9564 Defaults to @samp{"ALL:!LOW:!SSLv2:!EXP:!aNULL"}.
9567 @deftypevr {@code{dovecot-configuration} parameter} string ssl-crypto-device
9568 SSL crypto device to use, for valid values run "openssl engine".
9569 Defaults to @samp{""}.
9572 @deftypevr {@code{dovecot-configuration} parameter} string postmaster-address
9573 Address to use when sending rejection mails.
9574 Default is postmaster@@<your domain>. %d expands to recipient domain.
9575 Defaults to @samp{""}.
9578 @deftypevr {@code{dovecot-configuration} parameter} string hostname
9579 Hostname to use in various parts of sent mails (e.g. in Message-Id)
9580 and in LMTP replies. Default is the system's real hostname@@domain.
9581 Defaults to @samp{""}.
9584 @deftypevr {@code{dovecot-configuration} parameter} boolean quota-full-tempfail?
9585 If user is over quota, return with temporary failure instead of
9587 Defaults to @samp{#f}.
9590 @deftypevr {@code{dovecot-configuration} parameter} file-name sendmail-path
9591 Binary to use for sending mails.
9592 Defaults to @samp{"/usr/sbin/sendmail"}.
9595 @deftypevr {@code{dovecot-configuration} parameter} string submission-host
9596 If non-empty, send mails via this SMTP host[:port] instead of
9598 Defaults to @samp{""}.
9601 @deftypevr {@code{dovecot-configuration} parameter} string rejection-subject
9602 Subject: header to use for rejection mails. You can use the same
9603 variables as for @samp{rejection-reason} below.
9604 Defaults to @samp{"Rejected: %s"}.
9607 @deftypevr {@code{dovecot-configuration} parameter} string rejection-reason
9608 Human readable error message for rejection mails. You can use
9621 Defaults to @samp{"Your message to <%t> was automatically rejected:%n%r"}.
9624 @deftypevr {@code{dovecot-configuration} parameter} string recipient-delimiter
9625 Delimiter character between local-part and detail in email
9627 Defaults to @samp{"+"}.
9630 @deftypevr {@code{dovecot-configuration} parameter} string lda-original-recipient-header
9631 Header where the original recipient address (SMTP's RCPT TO:
9632 address) is taken from if not available elsewhere. With dovecot-lda -a
9633 parameter overrides this. A commonly used header for this is
9635 Defaults to @samp{""}.
9638 @deftypevr {@code{dovecot-configuration} parameter} boolean lda-mailbox-autocreate?
9639 Should saving a mail to a nonexistent mailbox automatically create
9641 Defaults to @samp{#f}.
9644 @deftypevr {@code{dovecot-configuration} parameter} boolean lda-mailbox-autosubscribe?
9645 Should automatically created mailboxes be also automatically
9647 Defaults to @samp{#f}.
9650 @deftypevr {@code{dovecot-configuration} parameter} non-negative-integer imap-max-line-length
9651 Maximum IMAP command line length. Some clients generate very long
9652 command lines with huge mailboxes, so you may need to raise this if you
9653 get "Too long argument" or "IMAP command line too large" errors
9655 Defaults to @samp{64000}.
9658 @deftypevr {@code{dovecot-configuration} parameter} string imap-logout-format
9659 IMAP logout format string:
9662 total number of bytes read from client
9664 total number of bytes sent to client.
9666 Defaults to @samp{"in=%i out=%o"}.
9669 @deftypevr {@code{dovecot-configuration} parameter} string imap-capability
9670 Override the IMAP CAPABILITY response. If the value begins with '+',
9671 add the given capabilities on top of the defaults (e.g. +XFOO XBAR).
9672 Defaults to @samp{""}.
9675 @deftypevr {@code{dovecot-configuration} parameter} string imap-idle-notify-interval
9676 How long to wait between "OK Still here" notifications when client
9678 Defaults to @samp{"2 mins"}.
9681 @deftypevr {@code{dovecot-configuration} parameter} string imap-id-send
9682 ID field names and values to send to clients. Using * as the value
9683 makes Dovecot use the default value. The following fields have default
9684 values currently: name, version, os, os-version, support-url,
9686 Defaults to @samp{""}.
9689 @deftypevr {@code{dovecot-configuration} parameter} string imap-id-log
9690 ID fields sent by client to log. * means everything.
9691 Defaults to @samp{""}.
9694 @deftypevr {@code{dovecot-configuration} parameter} space-separated-string-list imap-client-workarounds
9695 Workarounds for various client bugs:
9699 Send EXISTS/RECENT new mail notifications only when replying to NOOP and
9700 CHECK commands. Some clients ignore them otherwise, for example OSX
9701 Mail (<v2.1). Outlook Express breaks more badly though, without this it
9702 may show user "Message no longer in server" errors. Note that OE6
9703 still breaks even with this workaround if synchronization is set to
9706 @item tb-extra-mailbox-sep
9707 Thunderbird gets somehow confused with LAYOUT=fs (mbox and dbox) and
9708 adds extra @samp{/} suffixes to mailbox names. This option causes Dovecot to
9709 ignore the extra @samp{/} instead of treating it as invalid mailbox name.
9712 Show \Noselect flags for LSUB replies with LAYOUT=fs (e.g. mbox).
9713 This makes Thunderbird realize they aren't selectable and show them
9714 greyed out, instead of only later giving "not selectable" popup error.
9716 Defaults to @samp{()}.
9719 @deftypevr {@code{dovecot-configuration} parameter} string imap-urlauth-host
9720 Host allowed in URLAUTH URLs sent by client. "*" allows all.
9721 Defaults to @samp{""}.
9725 Whew! Lots of configuration options. The nice thing about it though is
9726 that GuixSD has a complete interface to Dovecot's configuration
9727 language. This allows not only a nice way to declare configurations,
9728 but also offers reflective capabilities as well: users can write code to
9729 inspect and transform configurations from within Scheme.
9731 However, it could be that you just want to get a @code{dovecot.conf} up
9732 and running. In that case, you can pass an
9733 @code{opaque-dovecot-configuration} as the @code{#:config} paramter to
9734 @code{dovecot-service}. As its name indicates, an opaque configuration
9735 does not have easy reflective capabilities.
9737 Available @code{opaque-dovecot-configuration} fields are:
9739 @deftypevr {@code{opaque-dovecot-configuration} parameter} package dovecot
9740 The dovecot package.
9743 @deftypevr {@code{opaque-dovecot-configuration} parameter} string string
9744 The contents of the @code{dovecot.conf}, as a string.
9747 For example, if your @code{dovecot.conf} is just the empty string, you
9748 could instantiate a dovecot service like this:
9751 (dovecot-service #:config
9752 (opaque-dovecot-configuration
9757 @subsubsection Web Services
9759 The @code{(gnu services web)} module provides the following service:
9761 @deffn {Scheme Procedure} nginx-service [#:nginx nginx] @
9762 [#:log-directory ``/var/log/nginx''] @
9763 [#:run-directory ``/var/run/nginx''] @
9766 Return a service that runs @var{nginx}, the nginx web server.
9768 The nginx daemon loads its runtime configuration from @var{config-file}.
9769 Log files are written to @var{log-directory} and temporary runtime data
9770 files are written to @var{run-directory}. For proper operation, these
9771 arguments should match what is in @var{config-file} to ensure that the
9772 directories are created when the service is activated.
9776 @node Various Services
9777 @subsubsection Various Services
9779 The @code{(gnu services lirc)} module provides the following service.
9781 @deffn {Scheme Procedure} lirc-service [#:lirc lirc] @
9782 [#:device #f] [#:driver #f] [#:config-file #f] @
9783 [#:extra-options '()]
9784 Return a service that runs @url{http://www.lirc.org,LIRC}, a daemon that
9785 decodes infrared signals from remote controls.
9787 Optionally, @var{device}, @var{driver} and @var{config-file}
9788 (configuration file name) may be specified. See @command{lircd} manual
9791 Finally, @var{extra-options} is a list of additional command-line options
9792 passed to @command{lircd}.
9795 @subsubsection Dictionary Services
9796 The @code{(gnu services dict)} module provides the following service:
9798 @deffn {Scheme Procedure} dicod-service [#:config (dicod-configuration)]
9799 Return a service that runs the @command{dicod} daemon, an implementation
9800 of DICT server (@pxref{Dicod,,, dico, GNU Dico Manual}).
9802 The optional @var{config} argument specifies the configuration for
9803 @command{dicod}, which should be a @code{<dicod-configuration>} object, by
9804 default it serves the GNU Collaborative International Dictonary of English.
9806 You can add @command{open localhost} to your @file{~/.dico} file to make
9807 @code{localhost} the default server for @command{dico} client
9808 (@pxref{Initialization File,,, dico, GNU Dico Manual}).
9811 @deftp {Data Type} dicod-configuration
9812 Data type representing the configuration of dicod.
9815 @item @code{dico} (default: @var{dico})
9816 Package object of the GNU Dico dictionary server.
9818 @item @code{interfaces} (default: @var{'("localhost")})
9819 This is the list of IP addresses and ports and possibly socket file
9820 names to listen to (@pxref{Server Settings, @code{listen} directive,,
9821 dico, GNU Dico Manual}).
9823 @item @code{databases} (default: @var{(list %dicod-database:gcide)})
9824 List of @code{<dicod-database>} objects denoting dictionaries to be served.
9828 @deftp {Data Type} dicod-database
9829 Data type representing a dictionary database.
9833 Name of the database, will be used in DICT commands.
9836 Name of the dicod module used by this database
9837 (@pxref{Modules,,, dico, GNU Dico Manual}).
9839 @item @code{options}
9840 List of strings or gexps representing the arguments for the module handler
9841 (@pxref{Handlers,,, dico, GNU Dico Manual}).
9845 @defvr {Scheme Variable} %dicod-database:gcide
9846 A @code{<dicod-database>} object serving the GNU Collaborative International
9847 Dictonary of English using the @code{gcide} package.
9850 @node Setuid Programs
9851 @subsection Setuid Programs
9853 @cindex setuid programs
9854 Some programs need to run with ``root'' privileges, even when they are
9855 launched by unprivileged users. A notorious example is the
9856 @command{passwd} program, which users can run to change their
9857 password, and which needs to access the @file{/etc/passwd} and
9858 @file{/etc/shadow} files---something normally restricted to root, for
9859 obvious security reasons. To address that, these executables are
9860 @dfn{setuid-root}, meaning that they always run with root privileges
9861 (@pxref{How Change Persona,,, libc, The GNU C Library Reference Manual},
9862 for more info about the setuid mechanism.)
9864 The store itself @emph{cannot} contain setuid programs: that would be a
9865 security issue since any user on the system can write derivations that
9866 populate the store (@pxref{The Store}). Thus, a different mechanism is
9867 used: instead of changing the setuid bit directly on files that are in
9868 the store, we let the system administrator @emph{declare} which programs
9869 should be setuid root.
9871 The @code{setuid-programs} field of an @code{operating-system}
9872 declaration contains a list of G-expressions denoting the names of
9873 programs to be setuid-root (@pxref{Using the Configuration System}).
9874 For instance, the @command{passwd} program, which is part of the Shadow
9875 package, can be designated by this G-expression (@pxref{G-Expressions}):
9878 #~(string-append #$shadow "/bin/passwd")
9881 A default set of setuid programs is defined by the
9882 @code{%setuid-programs} variable of the @code{(gnu system)} module.
9884 @defvr {Scheme Variable} %setuid-programs
9885 A list of G-expressions denoting common programs that are setuid-root.
9887 The list includes commands such as @command{passwd}, @command{ping},
9888 @command{su}, and @command{sudo}.
9891 Under the hood, the actual setuid programs are created in the
9892 @file{/run/setuid-programs} directory at system activation time. The
9893 files in this directory refer to the ``real'' binaries, which are in the
9896 @node X.509 Certificates
9897 @subsection X.509 Certificates
9899 @cindex HTTPS, certificates
9900 @cindex X.509 certificates
9902 Web servers available over HTTPS (that is, HTTP over the transport-layer
9903 security mechanism, TLS) send client programs an @dfn{X.509 certificate}
9904 that the client can then use to @emph{authenticate} the server. To do
9905 that, clients verify that the server's certificate is signed by a
9906 so-called @dfn{certificate authority} (CA). But to verify the CA's
9907 signature, clients must have first acquired the CA's certificate.
9909 Web browsers such as GNU@tie{}IceCat include their own set of CA
9910 certificates, such that they are able to verify CA signatures
9913 However, most other programs that can talk HTTPS---@command{wget},
9914 @command{git}, @command{w3m}, etc.---need to be told where CA
9915 certificates can be found.
9917 @cindex @code{nss-certs}
9918 In GuixSD, this is done by adding a package that provides certificates
9919 to the @code{packages} field of the @code{operating-system} declaration
9920 (@pxref{operating-system Reference}). GuixSD includes one such package,
9921 @code{nss-certs}, which is a set of CA certificates provided as part of
9922 Mozilla's Network Security Services.
9924 Note that it is @emph{not} part of @var{%base-packages}, so you need to
9925 explicitly add it. The @file{/etc/ssl/certs} directory, which is where
9926 most applications and libraries look for certificates by default, points
9927 to the certificates installed globally.
9929 Unprivileged users, including users of Guix on a foreign distro,
9930 can also install their own certificate package in
9931 their profile. A number of environment variables need to be defined so
9932 that applications and libraries know where to find them. Namely, the
9933 OpenSSL library honors the @code{SSL_CERT_DIR} and @code{SSL_CERT_FILE}
9934 variables. Some applications add their own environment variables; for
9935 instance, the Git version control system honors the certificate bundle
9936 pointed to by the @code{GIT_SSL_CAINFO} environment variable. Thus, you
9937 would typically run something like:
9940 $ guix package -i nss-certs
9941 $ export SSL_CERT_DIR="$HOME/.guix-profile/etc/ssl/certs"
9942 $ export SSL_CERT_FILE="$HOME/.guix-profile/etc/ssl/certs/ca-certificates.crt"
9943 $ export GIT_SSL_CAINFO="$SSL_CERT_FILE"
9946 @node Name Service Switch
9947 @subsection Name Service Switch
9949 @cindex name service switch
9951 The @code{(gnu system nss)} module provides bindings to the
9952 configuration file of the libc @dfn{name service switch} or @dfn{NSS}
9953 (@pxref{NSS Configuration File,,, libc, The GNU C Library Reference
9954 Manual}). In a nutshell, the NSS is a mechanism that allows libc to be
9955 extended with new ``name'' lookup methods for system databases, which
9956 includes host names, service names, user accounts, and more (@pxref{Name
9957 Service Switch, System Databases and Name Service Switch,, libc, The GNU
9958 C Library Reference Manual}).
9960 The NSS configuration specifies, for each system database, which lookup
9961 method is to be used, and how the various methods are chained
9962 together---for instance, under which circumstances NSS should try the
9963 next method in the list. The NSS configuration is given in the
9964 @code{name-service-switch} field of @code{operating-system} declarations
9965 (@pxref{operating-system Reference, @code{name-service-switch}}).
9968 @cindex .local, host name lookup
9969 As an example, the declaration below configures the NSS to use the
9970 @uref{http://0pointer.de/lennart/projects/nss-mdns/, @code{nss-mdns}
9971 back-end}, which supports host name lookups over multicast DNS (mDNS)
9972 for host names ending in @code{.local}:
9975 (name-service-switch
9976 (hosts (list %files ;first, check /etc/hosts
9978 ;; If the above did not succeed, try
9979 ;; with 'mdns_minimal'.
9981 (name "mdns_minimal")
9983 ;; 'mdns_minimal' is authoritative for
9984 ;; '.local'. When it returns "not found",
9985 ;; no need to try the next methods.
9986 (reaction (lookup-specification
9987 (not-found => return))))
9989 ;; Then fall back to DNS.
9993 ;; Finally, try with the "full" 'mdns'.
9998 Do not worry: the @code{%mdns-host-lookup-nss} variable (see below)
9999 contains this configuration, so you will not have to type it if all you
10000 want is to have @code{.local} host lookup working.
10002 Note that, in this case, in addition to setting the
10003 @code{name-service-switch} of the @code{operating-system} declaration,
10004 you also need to use @code{avahi-service} (@pxref{Networking Services,
10005 @code{avahi-service}}), or @var{%desktop-services}, which includes it
10006 (@pxref{Desktop Services}). Doing this makes @code{nss-mdns} accessible
10007 to the name service cache daemon (@pxref{Base Services,
10008 @code{nscd-service}}).
10010 For convenience, the following variables provide typical NSS
10013 @defvr {Scheme Variable} %default-nss
10014 This is the default name service switch configuration, a
10015 @code{name-service-switch} object.
10018 @defvr {Scheme Variable} %mdns-host-lookup-nss
10019 This is the name service switch configuration with support for host name
10020 lookup over multicast DNS (mDNS) for host names ending in @code{.local}.
10023 The reference for name service switch configuration is given below. It
10024 is a direct mapping of the configuration file format of the C library , so
10025 please refer to the C library manual for more information (@pxref{NSS
10026 Configuration File,,, libc, The GNU C Library Reference Manual}).
10027 Compared to the configuration file format of libc NSS, it has the advantage
10028 not only of adding this warm parenthetic feel that we like, but also
10029 static checks: you will know about syntax errors and typos as soon as you
10030 run @command{guix system}.
10032 @deftp {Data Type} name-service-switch
10034 This is the data type representation the configuration of libc's name
10035 service switch (NSS). Each field below represents one of the supported
10052 The system databases handled by the NSS. Each of these fields must be a
10053 list of @code{<name-service>} objects (see below).
10057 @deftp {Data Type} name-service
10059 This is the data type representing an actual name service and the
10060 associated lookup action.
10064 A string denoting the name service (@pxref{Services in the NSS
10065 configuration,,, libc, The GNU C Library Reference Manual}).
10067 Note that name services listed here must be visible to nscd. This is
10068 achieved by passing the @code{#:name-services} argument to
10069 @code{nscd-service} the list of packages providing the needed name
10070 services (@pxref{Base Services, @code{nscd-service}}).
10073 An action specified using the @code{lookup-specification} macro
10074 (@pxref{Actions in the NSS configuration,,, libc, The GNU C Library
10075 Reference Manual}). For example:
10078 (lookup-specification (unavailable => continue)
10079 (success => return))
10084 @node Initial RAM Disk
10085 @subsection Initial RAM Disk
10087 @cindex initial RAM disk (initrd)
10088 @cindex initrd (initial RAM disk)
10089 For bootstrapping purposes, the Linux-Libre kernel is passed an
10090 @dfn{initial RAM disk}, or @dfn{initrd}. An initrd contains a temporary
10091 root file system as well as an initialization script. The latter is
10092 responsible for mounting the real root file system, and for loading any
10093 kernel modules that may be needed to achieve that.
10095 The @code{initrd} field of an @code{operating-system} declaration allows
10096 you to specify which initrd you would like to use. The @code{(gnu
10097 system linux-initrd)} module provides two ways to build an initrd: the
10098 high-level @code{base-initrd} procedure, and the low-level
10099 @code{expression->initrd} procedure.
10101 The @code{base-initrd} procedure is intended to cover most common uses.
10102 For example, if you want to add a bunch of kernel modules to be loaded
10103 at boot time, you can define the @code{initrd} field of the operating
10104 system declaration like this:
10107 (initrd (lambda (file-systems . rest)
10108 ;; Create a standard initrd that has modules "foo.ko"
10109 ;; and "bar.ko", as well as their dependencies, in
10110 ;; addition to the modules available by default.
10111 (apply base-initrd file-systems
10112 #:extra-modules '("foo" "bar")
10116 The @code{base-initrd} procedure also handles common use cases that
10117 involves using the system as a QEMU guest, or as a ``live'' system with
10118 volatile root file system.
10120 The initial RAM disk produced by @code{base-initrd} honors several
10121 options passed on the Linux kernel command line (that is, arguments
10122 passed @i{via} the @code{linux} command of GRUB, or the
10123 @code{-append} option) of QEMU, notably:
10126 @item --load=@var{boot}
10127 Tell the initial RAM disk to load @var{boot}, a file containing a Scheme
10128 program, once it has mounted the root file system.
10130 GuixSD uses this option to yield control to a boot program that runs the
10131 service activation programs and then spawns the GNU@tie{}Shepherd, the
10132 initialization system.
10134 @item --root=@var{root}
10135 Mount @var{root} as the root file system. @var{root} can be a
10136 device name like @code{/dev/sda1}, a partition label, or a partition
10139 @item --system=@var{system}
10140 Have @file{/run/booted-system} and @file{/run/current-system} point to
10143 @item modprobe.blacklist=@var{modules}@dots{}
10144 @cindex module, black-listing
10145 @cindex black list, of kernel modules
10146 Instruct the initial RAM disk as well as the @command{modprobe} command
10147 (from the kmod package) to refuse to load @var{modules}. @var{modules}
10148 must be a comma-separated list of module names---e.g.,
10149 @code{usbkbd,9pnet}.
10152 Start a read-eval-print loop (REPL) from the initial RAM disk before it
10153 tries to load kernel modules and to mount the root file system. Our
10154 marketing team calls it @dfn{boot-to-Guile}. The Schemer in you will
10155 love it. @xref{Using Guile Interactively,,, guile, GNU Guile Reference
10156 Manual}, for more information on Guile's REPL.
10160 Now that you know all the features that initial RAM disks produced by
10161 @code{base-initrd} provide, here is how to use it and customize it
10164 @deffn {Monadic Procedure} base-initrd @var{file-systems} @
10165 [#:qemu-networking? #f] [#:virtio? #t] [#:volatile-root? #f] @
10166 [#:extra-modules '()] [#:mapped-devices '()]
10167 Return a monadic derivation that builds a generic initrd. @var{file-systems} is
10168 a list of file systems to be mounted by the initrd, possibly in addition to
10169 the root file system specified on the kernel command line via @code{--root}.
10170 @var{mapped-devices} is a list of device mappings to realize before
10171 @var{file-systems} are mounted (@pxref{Mapped Devices}).
10173 When @var{qemu-networking?} is true, set up networking with the standard QEMU
10174 parameters. When @var{virtio?} is true, load additional modules so that the
10175 initrd can be used as a QEMU guest with para-virtualized I/O drivers.
10177 When @var{volatile-root?} is true, the root file system is writable but any changes
10180 The initrd is automatically populated with all the kernel modules necessary
10181 for @var{file-systems} and for the given options. However, additional kernel
10182 modules can be listed in @var{extra-modules}. They will be added to the initrd, and
10183 loaded at boot time in the order in which they appear.
10186 Needless to say, the initrds we produce and use embed a
10187 statically-linked Guile, and the initialization program is a Guile
10188 program. That gives a lot of flexibility. The
10189 @code{expression->initrd} procedure builds such an initrd, given the
10190 program to run in that initrd.
10192 @deffn {Monadic Procedure} expression->initrd @var{exp} @
10193 [#:guile %guile-static-stripped] [#:name "guile-initrd"]
10194 Return a derivation that builds a Linux initrd (a gzipped cpio archive)
10195 containing @var{guile} and that evaluates @var{exp}, a G-expression,
10196 upon booting. All the derivations referenced by @var{exp} are
10197 automatically copied to the initrd.
10200 @node GRUB Configuration
10201 @subsection GRUB Configuration
10204 @cindex boot loader
10206 The operating system uses GNU@tie{}GRUB as its boot loader
10207 (@pxref{Overview, overview of GRUB,, grub, GNU GRUB Manual}). It is
10208 configured using a @code{grub-configuration} declaration. This data type
10209 is exported by the @code{(gnu system grub)} module and described below.
10211 @deftp {Data Type} grub-configuration
10212 The type of a GRUB configuration declaration.
10216 @item @code{device}
10217 This is a string denoting the boot device. It must be a device name
10218 understood by the @command{grub-install} command, such as
10219 @code{/dev/sda} or @code{(hd0)} (@pxref{Invoking grub-install,,, grub,
10222 @item @code{menu-entries} (default: @code{()})
10223 A possibly empty list of @code{menu-entry} objects (see below), denoting
10224 entries to appear in the GRUB boot menu, in addition to the current
10225 system entry and the entry pointing to previous system generations.
10227 @item @code{default-entry} (default: @code{0})
10228 The index of the default boot menu entry. Index 0 is for the entry of the
10231 @item @code{timeout} (default: @code{5})
10232 The number of seconds to wait for keyboard input before booting. Set to
10233 0 to boot immediately, and to -1 to wait indefinitely.
10235 @item @code{theme} (default: @var{%default-theme})
10236 The @code{grub-theme} object describing the theme to use.
10241 Should you want to list additional boot menu entries @i{via} the
10242 @code{menu-entries} field above, you will need to create them with the
10243 @code{menu-entry} form:
10245 @deftp {Data Type} menu-entry
10246 The type of an entry in the GRUB boot menu.
10251 The label to show in the menu---e.g., @code{"GNU"}.
10254 The Linux kernel to boot.
10256 @item @code{linux-arguments} (default: @code{()})
10257 The list of extra Linux kernel command-line arguments---e.g.,
10258 @code{("console=ttyS0")}.
10260 @item @code{initrd}
10261 A G-Expression or string denoting the file name of the initial RAM disk
10262 to use (@pxref{G-Expressions}).
10267 @c FIXME: Write documentation once it's stable.
10268 Themes are created using the @code{grub-theme} form, which is not
10271 @defvr {Scheme Variable} %default-theme
10272 This is the default GRUB theme used by the operating system, with a
10273 fancy background image displaying the GNU and Guix logos.
10277 @node Invoking guix system
10278 @subsection Invoking @code{guix system}
10280 Once you have written an operating system declaration as seen in the
10281 previous section, it can be @dfn{instantiated} using the @command{guix
10282 system} command. The synopsis is:
10285 guix system @var{options}@dots{} @var{action} @var{file}
10288 @var{file} must be the name of a file containing an
10289 @code{operating-system} declaration. @var{action} specifies how the
10290 operating system is instantiated. Currently the following values are
10295 Build the operating system described in @var{file}, activate it, and
10296 switch to it@footnote{This action is usable only on systems already
10299 This effects all the configuration specified in @var{file}: user
10300 accounts, system services, global package list, setuid programs, etc.
10301 The command starts system services specified in @var{file} that are not
10302 currently running; if a service is currently running, it does not
10303 attempt to upgrade it since this would not be possible without stopping it
10306 It also adds a GRUB menu entry for the new OS configuration, and moves
10307 entries for older configurations to a submenu---unless
10308 @option{--no-grub} is passed.
10311 @c The paragraph below refers to the problem discussed at
10312 @c <http://lists.gnu.org/archive/html/guix-devel/2014-08/msg00057.html>.
10313 It is highly recommended to run @command{guix pull} once before you run
10314 @command{guix system reconfigure} for the first time (@pxref{Invoking
10315 guix pull}). Failing to do that you would see an older version of Guix
10316 once @command{reconfigure} has completed.
10320 Build the derivation of the operating system, which includes all the
10321 configuration files and programs needed to boot and run the system.
10322 This action does not actually install anything.
10325 Populate the given directory with all the files necessary to run the
10326 operating system specified in @var{file}. This is useful for first-time
10327 installations of GuixSD. For instance:
10330 guix system init my-os-config.scm /mnt
10333 copies to @file{/mnt} all the store items required by the configuration
10334 specified in @file{my-os-config.scm}. This includes configuration
10335 files, packages, and so on. It also creates other essential files
10336 needed for the system to operate correctly---e.g., the @file{/etc},
10337 @file{/var}, and @file{/run} directories, and the @file{/bin/sh} file.
10339 This command also installs GRUB on the device specified in
10340 @file{my-os-config}, unless the @option{--no-grub} option was passed.
10343 @cindex virtual machine
10345 @anchor{guix system vm}
10346 Build a virtual machine that contains the operating system declared in
10347 @var{file}, and return a script to run that virtual machine (VM).
10348 Arguments given to the script are passed to QEMU.
10350 The VM shares its store with the host system.
10352 Additional file systems can be shared between the host and the VM using
10353 the @code{--share} and @code{--expose} command-line options: the former
10354 specifies a directory to be shared with write access, while the latter
10355 provides read-only access to the shared directory.
10357 The example below creates a VM in which the user's home directory is
10358 accessible read-only, and where the @file{/exchange} directory is a
10359 read-write mapping of @file{$HOME/tmp} on the host:
10362 guix system vm my-config.scm \
10363 --expose=$HOME --share=$HOME/tmp=/exchange
10366 On GNU/Linux, the default is to boot directly to the kernel; this has
10367 the advantage of requiring only a very tiny root disk image since the
10368 store of the host can then be mounted.
10370 The @code{--full-boot} option forces a complete boot sequence, starting
10371 with the bootloader. This requires more disk space since a root image
10372 containing at least the kernel, initrd, and bootloader data files must
10373 be created. The @code{--image-size} option can be used to specify the
10378 Return a virtual machine or disk image of the operating system declared
10379 in @var{file} that stands alone. Use the @option{--image-size} option
10380 to specify the size of the image.
10382 When using @code{vm-image}, the returned image is in qcow2 format, which
10383 the QEMU emulator can efficiently use. @xref{Running GuixSD in a VM},
10384 for more information on how to run the image in a virtual machine.
10386 When using @code{disk-image}, a raw disk image is produced; it can be
10387 copied as is to a USB stick, for instance. Assuming @code{/dev/sdc} is
10388 the device corresponding to a USB stick, one can copy the image to it
10389 using the following command:
10392 # dd if=$(guix system disk-image my-os.scm) of=/dev/sdc
10396 Return a script to run the operating system declared in @var{file}
10397 within a container. Containers are a set of lightweight isolation
10398 mechanisms provided by the kernel Linux-libre. Containers are
10399 substantially less resource-demanding than full virtual machines since
10400 the kernel, shared objects, and other resources can be shared with the
10401 host system; this also means they provide thinner isolation.
10403 Currently, the script must be run as root in order to support more than
10404 a single user and group. The container shares its store with the host
10407 As with the @code{vm} action (@pxref{guix system vm}), additional file
10408 systems to be shared between the host and container can be specified
10409 using the @option{--share} and @option{--expose} options:
10412 guix system container my-config.scm \
10413 --expose=$HOME --share=$HOME/tmp=/exchange
10417 This option requires Linux-libre 3.19 or newer.
10422 @var{options} can contain any of the common build options (@pxref{Common
10423 Build Options}). In addition, @var{options} can contain one of the
10427 @item --system=@var{system}
10428 @itemx -s @var{system}
10429 Attempt to build for @var{system} instead of the host system type.
10430 This works as per @command{guix build} (@pxref{Invoking guix build}).
10434 Return the derivation file name of the given operating system without
10437 @item --image-size=@var{size}
10438 For the @code{vm-image} and @code{disk-image} actions, create an image
10439 of the given @var{size}. @var{size} may be a number of bytes, or it may
10440 include a unit as a suffix (@pxref{Block size, size specifications,,
10441 coreutils, GNU Coreutils}).
10443 @item --on-error=@var{strategy}
10444 Apply @var{strategy} when an error occurs when reading @var{file}.
10445 @var{strategy} may be one of the following:
10448 @item nothing-special
10449 Report the error concisely and exit. This is the default strategy.
10452 Likewise, but also display a backtrace.
10455 Report the error and enter Guile's debugger. From there, you can run
10456 commands such as @code{,bt} to get a backtrace, @code{,locals} to
10457 display local variable values, and more generally inspect the state of the
10458 program. @xref{Debug Commands,,, guile, GNU Guile Reference Manual}, for
10459 a list of available debugging commands.
10464 All the actions above, except @code{build} and @code{init},
10465 can use KVM support in the Linux-libre kernel. Specifically, if the
10466 machine has hardware virtualization support, the corresponding
10467 KVM kernel module should be loaded, and the @file{/dev/kvm} device node
10468 must exist and be readable and writable by the user and by the
10469 build users of the daemon (@pxref{Build Environment Setup}).
10472 Once you have built, configured, re-configured, and re-re-configured
10473 your GuixSD installation, you may find it useful to list the operating
10474 system generations available on disk---and that you can choose from the
10479 @item list-generations
10480 List a summary of each generation of the operating system available on
10481 disk, in a human-readable way. This is similar to the
10482 @option{--list-generations} option of @command{guix package}
10483 (@pxref{Invoking guix package}).
10485 Optionally, one can specify a pattern, with the same syntax that is used
10486 in @command{guix package --list-generations}, to restrict the list of
10487 generations displayed. For instance, the following command displays
10488 generations that are up to 10 days old:
10491 $ guix system list-generations 10d
10496 The @command{guix system} command has even more to offer! The following
10497 sub-commands allow you to visualize how your system services relate to
10500 @anchor{system-extension-graph}
10503 @item extension-graph
10504 Emit in Dot/Graphviz format to standard output the @dfn{service
10505 extension graph} of the operating system defined in @var{file}
10506 (@pxref{Service Composition}, for more information on service
10512 $ guix system extension-graph @var{file} | dot -Tpdf > services.pdf
10515 produces a PDF file showing the extension relations among services.
10517 @anchor{system-shepherd-graph}
10518 @item shepherd-graph
10519 Emit in Dot/Graphviz format to standard output the @dfn{dependency
10520 graph} of shepherd services of the operating system defined in
10521 @var{file}. @xref{Shepherd Services}, for more information and for an
10526 @node Running GuixSD in a VM
10527 @subsection Running GuixSD in a Virtual Machine
10529 One way to run GuixSD in a virtual machine (VM) is to build a GuixSD
10530 virtual machine image using @command{guix system vm-image}
10531 (@pxref{Invoking guix system}). The returned image is in qcow2 format,
10532 which the @uref{http://qemu.org/, QEMU emulator} can efficiently use.
10534 To run the image in QEMU, copy it out of the store (@pxref{The Store})
10535 and give yourself permission to write to the copy. When invoking QEMU,
10536 you must choose a system emulator that is suitable for your hardware
10537 platform. Here is a minimal QEMU invocation that will boot the result
10538 of @command{guix system vm-image} on x86_64 hardware:
10541 $ qemu-system-x86_64 \
10542 -net user -net nic,model=virtio \
10543 -enable-kvm -m 256 /tmp/qemu-image
10546 Here is what each of these options means:
10549 @item qemu-system-x86_64
10550 This specifies the hardware platform to emulate. This should match the
10554 Enable the unprivileged user-mode network stack. The guest OS can
10555 access the host but not vice versa. This is the simplest way to get the
10556 guest OS online. If you do not choose a network stack, the boot will
10559 @item -net nic,model=virtio
10560 You must create a network interface of a given model. If you do not
10561 create a NIC, the boot will fail. Assuming your hardware platform is
10562 x86_64, you can get a list of available NIC models by running
10563 @command{qemu-system-x86_64 -net nic,model=help}.
10566 If your system has hardware virtualization extensions, enabling the
10567 virtual machine support (KVM) of the Linux kernel will make things run
10571 RAM available to the guest OS, in mebibytes. Defaults to 128@tie{}MiB,
10572 which may be insufficent for some operations.
10574 @item /tmp/qemu-image
10575 The file name of the qcow2 image.
10578 @node Defining Services
10579 @subsection Defining Services
10581 The previous sections show the available services and how one can combine
10582 them in an @code{operating-system} declaration. But how do we define
10583 them in the first place? And what is a service anyway?
10586 * Service Composition:: The model for composing services.
10587 * Service Types and Services:: Types and services.
10588 * Service Reference:: API reference.
10589 * Shepherd Services:: A particular type of service.
10592 @node Service Composition
10593 @subsubsection Service Composition
10597 Here we define a @dfn{service} as, broadly, something that extends the
10598 functionality of the operating system. Often a service is a process---a
10599 @dfn{daemon}---started when the system boots: a secure shell server, a
10600 Web server, the Guix build daemon, etc. Sometimes a service is a daemon
10601 whose execution can be triggered by another daemon---e.g., an FTP server
10602 started by @command{inetd} or a D-Bus service activated by
10603 @command{dbus-daemon}. Occasionally, a service does not map to a
10604 daemon. For instance, the ``account'' service collects user accounts
10605 and makes sure they exist when the system runs; the ``udev'' service
10606 collects device management rules and makes them available to the eudev
10607 daemon; the @file{/etc} service populates the @file{/etc} directory
10610 @cindex service extensions
10611 GuixSD services are connected by @dfn{extensions}. For instance, the
10612 secure shell service @emph{extends} the Shepherd---the GuixSD
10613 initialization system, running as PID@tie{}1---by giving it the command
10614 lines to start and stop the secure shell daemon (@pxref{Networking
10615 Services, @code{lsh-service}}); the UPower service extends the D-Bus
10616 service by passing it its @file{.service} specification, and extends the
10617 udev service by passing it device management rules (@pxref{Desktop
10618 Services, @code{upower-service}}); the Guix daemon service extends the
10619 Shepherd by passing it the command lines to start and stop the daemon,
10620 and extends the account service by passing it a list of required build
10621 user accounts (@pxref{Base Services}).
10623 All in all, services and their ``extends'' relations form a directed
10624 acyclic graph (DAG). If we represent services as boxes and extensions
10625 as arrows, a typical system might provide something like this:
10627 @image{images/service-graph,,5in,Typical service extension graph.}
10629 @cindex system service
10630 At the bottom, we see the @dfn{system service}, which produces the
10631 directory containing everything to run and boot the system, as returned
10632 by the @command{guix system build} command. @xref{Service Reference},
10633 to learn about the other service types shown here.
10634 @xref{system-extension-graph, the @command{guix system extension-graph}
10635 command}, for information on how to generate this representation for a
10636 particular operating system definition.
10638 @cindex service types
10639 Technically, developers can define @dfn{service types} to express these
10640 relations. There can be any number of services of a given type on the
10641 system---for instance, a system running two instances of the GNU secure
10642 shell server (lsh) has two instances of @var{lsh-service-type}, with
10643 different parameters.
10645 The following section describes the programming interface for service
10646 types and services.
10648 @node Service Types and Services
10649 @subsubsection Service Types and Services
10651 A @dfn{service type} is a node in the DAG described above. Let us start
10652 with a simple example, the service type for the Guix build daemon
10653 (@pxref{Invoking guix-daemon}):
10656 (define guix-service-type
10660 (list (service-extension shepherd-root-service-type guix-shepherd-service)
10661 (service-extension account-service-type guix-accounts)
10662 (service-extension activation-service-type guix-activation)))))
10666 It defines two things:
10670 A name, whose sole purpose is to make inspection and debugging easier.
10673 A list of @dfn{service extensions}, where each extension designates the
10674 target service type and a procedure that, given the parameters of the
10675 service, returns a list of objects to extend the service of that type.
10677 Every service type has at least one service extension. The only
10678 exception is the @dfn{boot service type}, which is the ultimate service.
10681 In this example, @var{guix-service-type} extends three services:
10684 @item shepherd-root-service-type
10685 The @var{guix-shepherd-service} procedure defines how the Shepherd
10686 service is extended. Namely, it returns a @code{<shepherd-service>}
10687 object that defines how @command{guix-daemon} is started and stopped
10688 (@pxref{Shepherd Services}).
10690 @item account-service-type
10691 This extension for this service is computed by @var{guix-accounts},
10692 which returns a list of @code{user-group} and @code{user-account}
10693 objects representing the build user accounts (@pxref{Invoking
10696 @item activation-service-type
10697 Here @var{guix-activation} is a procedure that returns a gexp, which is
10698 a code snippet to run at ``activation time''---e.g., when the service is
10702 A service of this type is instantiated like this:
10705 (service guix-service-type
10706 (guix-configuration
10708 (use-substitutes? #f)))
10711 The second argument to the @code{service} form is a value representing
10712 the parameters of this specific service instance.
10713 @xref{guix-configuration-type, @code{guix-configuration}}, for
10714 information about the @code{guix-configuration} data type.
10716 @var{guix-service-type} is quite simple because it extends other
10717 services but is not extensible itself.
10719 @c @subsubsubsection Extensible Service Types
10721 The service type for an @emph{extensible} service looks like this:
10724 (define udev-service-type
10725 (service-type (name 'udev)
10727 (list (service-extension shepherd-root-service-type
10728 udev-shepherd-service)))
10730 (compose concatenate) ;concatenate the list of rules
10731 (extend (lambda (config rules)
10733 (($ <udev-configuration> udev initial-rules)
10734 (udev-configuration
10735 (udev udev) ;the udev package to use
10736 (rules (append initial-rules rules)))))))))
10739 This is the service type for the
10740 @uref{https://wiki.gentoo.org/wiki/Project:Eudev, eudev device
10741 management daemon}. Compared to the previous example, in addition to an
10742 extension of @var{shepherd-root-service-type}, we see two new fields:
10746 This is the procedure to @dfn{compose} the list of extensions to
10747 services of this type.
10749 Services can extend the udev service by passing it lists of rules; we
10750 compose those extensions simply by concatenating them.
10753 This procedure defines how the value of the service is @dfn{extended} with
10754 the composition of the extensions.
10756 Udev extensions are composed into a list of rules, but the udev service
10757 value is itself a @code{<udev-configuration>} record. So here, we
10758 extend that record by appending the list of rules it contains to the
10759 list of contributed rules.
10762 There can be only one instance of an extensible service type such as
10763 @var{udev-service-type}. If there were more, the
10764 @code{service-extension} specifications would be ambiguous.
10766 Still here? The next section provides a reference of the programming
10767 interface for services.
10769 @node Service Reference
10770 @subsubsection Service Reference
10772 We have seen an overview of service types (@pxref{Service Types and
10773 Services}). This section provides a reference on how to manipulate
10774 services and service types. This interface is provided by the
10775 @code{(gnu services)} module.
10777 @deffn {Scheme Procedure} service @var{type} @var{value}
10778 Return a new service of @var{type}, a @code{<service-type>} object (see
10779 below.) @var{value} can be any object; it represents the parameters of
10780 this particular service instance.
10783 @deffn {Scheme Procedure} service? @var{obj}
10784 Return true if @var{obj} is a service.
10787 @deffn {Scheme Procedure} service-kind @var{service}
10788 Return the type of @var{service}---i.e., a @code{<service-type>} object.
10791 @deffn {Scheme Procedure} service-parameters @var{service}
10792 Return the value associated with @var{service}. It represents its
10796 Here is an example of how a service is created and manipulated:
10800 (service nginx-service-type
10801 (nginx-configuration
10803 (log-directory log-directory)
10804 (run-directory run-directory)
10805 (file config-file))))
10810 (eq? (service-kind s) nginx-service-type)
10814 The @code{modify-services} form provides a handy way to change the
10815 parameters of some of the services of a list such as
10816 @var{%base-services} (@pxref{Base Services, @code{%base-services}}). It
10817 evalutes to a list of services. Of course, you could always use
10818 standard list combinators such as @code{map} and @code{fold} to do that
10819 (@pxref{SRFI-1, List Library,, guile, GNU Guile Reference Manual});
10820 @code{modify-services} simply provides a more concise form for this
10823 @deffn {Scheme Syntax} modify-services @var{services} @
10824 (@var{type} @var{variable} => @var{body}) @dots{}
10826 Modify the services listed in @var{services} according to the given
10827 clauses. Each clause has the form:
10830 (@var{type} @var{variable} => @var{body})
10833 where @var{type} is a service type---e.g.,
10834 @code{guix-service-type}---and @var{variable} is an identifier that is
10835 bound within the @var{body} to the service parameters---e.g., a
10836 @code{guix-configuration} instance---of the original service of that
10839 The @var{body} should evaluate to the new service parameters, which will
10840 be used to configure the new service. This new service will replace the
10841 original in the resulting list. Because a service's service parameters
10842 are created using @code{define-record-type*}, you can write a succint
10843 @var{body} that evaluates to the new service parameters by using the
10844 @code{inherit} feature that @code{define-record-type*} provides.
10846 @xref{Using the Configuration System}, for example usage.
10850 Next comes the programming interface for service types. This is
10851 something you want to know when writing new service definitions, but not
10852 necessarily when simply looking for ways to customize your
10853 @code{operating-system} declaration.
10855 @deftp {Data Type} service-type
10856 @cindex service type
10857 This is the representation of a @dfn{service type} (@pxref{Service Types
10862 This is a symbol, used only to simplify inspection and debugging.
10864 @item @code{extensions}
10865 A non-empty list of @code{<service-extension>} objects (see below).
10867 @item @code{compose} (default: @code{#f})
10868 If this is @code{#f}, then the service type denotes services that cannot
10869 be extended---i.e., services that do not receive ``values'' from other
10872 Otherwise, it must be a one-argument procedure. The procedure is called
10873 by @code{fold-services} and is passed a list of values collected from
10874 extensions. It must return a value that is a valid parameter value for
10875 the service instance.
10877 @item @code{extend} (default: @code{#f})
10878 If this is @code{#f}, services of this type cannot be extended.
10880 Otherwise, it must be a two-argument procedure: @code{fold-services}
10881 calls it, passing it the initial value of the service as the first argument
10882 and the result of applying @code{compose} to the extension values as the
10886 @xref{Service Types and Services}, for examples.
10889 @deffn {Scheme Procedure} service-extension @var{target-type} @
10891 Return a new extension for services of type @var{target-type}.
10892 @var{compute} must be a one-argument procedure: @code{fold-services}
10893 calls it, passing it the value associated with the service that provides
10894 the extension; it must return a valid value for the target service.
10897 @deffn {Scheme Procedure} service-extension? @var{obj}
10898 Return true if @var{obj} is a service extension.
10901 At the core of the service abstraction lies the @code{fold-services}
10902 procedure, which is responsible for ``compiling'' a list of services
10903 down to a single directory that contains everything needed to boot and
10904 run the system---the directory shown by the @command{guix system build}
10905 command (@pxref{Invoking guix system}). In essence, it propagates
10906 service extensions down the service graph, updating each node parameters
10907 on the way, until it reaches the root node.
10909 @deffn {Scheme Procedure} fold-services @var{services} @
10910 [#:target-type @var{system-service-type}]
10911 Fold @var{services} by propagating their extensions down to the root of
10912 type @var{target-type}; return the root service adjusted accordingly.
10915 Lastly, the @code{(gnu services)} module also defines several essential
10916 service types, some of which are listed below.
10918 @defvr {Scheme Variable} system-service-type
10919 This is the root of the service graph. It produces the system directory
10920 as returned by the @command{guix system build} command.
10923 @defvr {Scheme Variable} boot-service-type
10924 The type of the ``boot service'', which produces the @dfn{boot script}.
10925 The boot script is what the initial RAM disk runs when booting.
10928 @defvr {Scheme Variable} etc-service-type
10929 The type of the @file{/etc} service. This service can be extended by
10930 passing it name/file tuples such as:
10933 (list `("issue" ,(plain-file "issue" "Welcome!\n")))
10936 In this example, the effect would be to add an @file{/etc/issue} file
10937 pointing to the given file.
10940 @defvr {Scheme Variable} setuid-program-service-type
10941 Type for the ``setuid-program service''. This service collects lists of
10942 executable file names, passed as gexps, and adds them to the set of
10943 setuid-root programs on the system (@pxref{Setuid Programs}).
10946 @defvr {Scheme Variable} profile-service-type
10947 Type of the service that populates the @dfn{system profile}---i.e., the
10948 programs under @file{/run/current-system/profile}. Other services can
10949 extend it by passing it lists of packages to add to the system profile.
10953 @node Shepherd Services
10954 @subsubsection Shepherd Services
10957 @cindex init system
10958 The @code{(gnu services shepherd)} module provides a way to define
10959 services managed by the GNU@tie{}Shepherd, which is the GuixSD
10960 initialization system---the first process that is started when the
10961 system boots, also known as PID@tie{}1
10962 (@pxref{Introduction,,, shepherd, The GNU Shepherd Manual}).
10964 Services in the Shepherd can depend on each other. For instance, the
10965 SSH daemon may need to be started after the syslog daemon has been
10966 started, which in turn can only happen once all the file systems have
10967 been mounted. The simple operating system defined earlier (@pxref{Using
10968 the Configuration System}) results in a service graph like this:
10970 @image{images/shepherd-graph,,5in,Typical shepherd service graph.}
10972 You can actually generate such a graph for any operating system
10973 definition using the @command{guix system shepherd-graph} command
10974 (@pxref{system-shepherd-graph, @command{guix system shepherd-graph}}).
10976 The @var{%shepherd-root-service} is a service object representing
10977 PID@tie{}1, of type @var{shepherd-root-service-type}; it can be extended
10978 by passing it lists of @code{<shepherd-service>} objects.
10980 @deftp {Data Type} shepherd-service
10981 The data type representing a service managed by the Shepherd.
10984 @item @code{provision}
10985 This is a list of symbols denoting what the service provides.
10987 These are the names that may be passed to @command{herd start},
10988 @command{herd status}, and similar commands (@pxref{Invoking herd,,,
10989 shepherd, The GNU Shepherd Manual}). @xref{Slots of services, the
10990 @code{provides} slot,, shepherd, The GNU Shepherd Manual}, for details.
10992 @item @code{requirements} (default: @code{'()})
10993 List of symbols denoting the Shepherd services this one depends on.
10995 @item @code{respawn?} (default: @code{#t})
10996 Whether to restart the service when it stops, for instance when the
10997 underlying process dies.
11000 @itemx @code{stop} (default: @code{#~(const #f)})
11001 The @code{start} and @code{stop} fields refer to the Shepherd's
11002 facilities to start and stop processes (@pxref{Service De- and
11003 Constructors,,, shepherd, The GNU Shepherd Manual}). They are given as
11004 G-expressions that get expanded in the Shepherd configuration file
11005 (@pxref{G-Expressions}).
11007 @item @code{documentation}
11008 A documentation string, as shown when running:
11011 herd doc @var{service-name}
11014 where @var{service-name} is one of the symbols in @var{provision}
11015 (@pxref{Invoking herd,,, shepherd, The GNU Shepherd Manual}).
11017 @item @code{modules} (default: @var{%default-modules})
11018 This is the list of modules that must be in scope when @code{start} and
11019 @code{stop} are evaluated.
11024 @defvr {Scheme Variable} shepherd-root-service-type
11025 The service type for the Shepherd ``root service''---i.e., PID@tie{}1.
11027 This is the service type that extensions target when they want to create
11028 shepherd services (@pxref{Service Types and Services}, for an example).
11029 Each extension must pass a list of @code{<shepherd-service>}.
11032 @defvr {Scheme Variable} %shepherd-root-service
11033 This service represents PID@tie{}1.
11037 @node Installing Debugging Files
11038 @section Installing Debugging Files
11040 @cindex debugging files
11041 Program binaries, as produced by the GCC compilers for instance, are
11042 typically written in the ELF format, with a section containing
11043 @dfn{debugging information}. Debugging information is what allows the
11044 debugger, GDB, to map binary code to source code; it is required to
11045 debug a compiled program in good conditions.
11047 The problem with debugging information is that is takes up a fair amount
11048 of disk space. For example, debugging information for the GNU C Library
11049 weighs in at more than 60 MiB. Thus, as a user, keeping all the
11050 debugging info of all the installed programs is usually not an option.
11051 Yet, space savings should not come at the cost of an impediment to
11052 debugging---especially in the GNU system, which should make it easier
11053 for users to exert their computing freedom (@pxref{GNU Distribution}).
11055 Thankfully, the GNU Binary Utilities (Binutils) and GDB provide a
11056 mechanism that allows users to get the best of both worlds: debugging
11057 information can be stripped from the binaries and stored in separate
11058 files. GDB is then able to load debugging information from those files,
11059 when they are available (@pxref{Separate Debug Files,,, gdb, Debugging
11062 The GNU distribution takes advantage of this by storing debugging
11063 information in the @code{lib/debug} sub-directory of a separate package
11064 output unimaginatively called @code{debug} (@pxref{Packages with
11065 Multiple Outputs}). Users can choose to install the @code{debug} output
11066 of a package when they need it. For instance, the following command
11067 installs the debugging information for the GNU C Library and for GNU
11071 guix package -i glibc:debug guile:debug
11074 GDB must then be told to look for debug files in the user's profile, by
11075 setting the @code{debug-file-directory} variable (consider setting it
11076 from the @file{~/.gdbinit} file, @pxref{Startup,,, gdb, Debugging with
11080 (gdb) set debug-file-directory ~/.guix-profile/lib/debug
11083 From there on, GDB will pick up debugging information from the
11084 @code{.debug} files under @file{~/.guix-profile/lib/debug}.
11086 In addition, you will most likely want GDB to be able to show the source
11087 code being debugged. To do that, you will have to unpack the source
11088 code of the package of interest (obtained with @code{guix build
11089 --source}, @pxref{Invoking guix build}), and to point GDB to that source
11090 directory using the @code{directory} command (@pxref{Source Path,
11091 @code{directory},, gdb, Debugging with GDB}).
11093 @c XXX: keep me up-to-date
11094 The @code{debug} output mechanism in Guix is implemented by the
11095 @code{gnu-build-system} (@pxref{Build Systems}). Currently, it is
11096 opt-in---debugging information is available only for the packages
11097 with definitions explicitly declaring a @code{debug} output. This may be
11098 changed to opt-out in the future if our build farm servers can handle
11099 the load. To check whether a package has a @code{debug} output, use
11100 @command{guix package --list-available} (@pxref{Invoking guix package}).
11103 @node Security Updates
11104 @section Security Updates
11106 @cindex security updates
11107 @cindex security vulnerabilities
11108 Occasionally, important security vulnerabilities are discovered in software
11109 packages and must be patched. Guix developers try hard to keep track of
11110 known vulnerabilities and to apply fixes as soon as possible in the
11111 @code{master} branch of Guix (we do not yet provide a ``stable'' branch
11112 containing only security updates.) The @command{guix lint} tool helps
11113 developers find out about vulnerable versions of software packages in the
11118 gnu/packages/base.scm:652:2: glibc-2.21: probably vulnerable to CVE-2015-1781, CVE-2015-7547
11119 gnu/packages/gcc.scm:334:2: gcc-4.9.3: probably vulnerable to CVE-2015-5276
11120 gnu/packages/image.scm:312:2: openjpeg-2.1.0: probably vulnerable to CVE-2016-1923, CVE-2016-1924
11124 @xref{Invoking guix lint}, for more information.
11127 As of version @value{VERSION}, the feature described below is considered
11131 Guix follows a functional
11132 package management discipline (@pxref{Introduction}), which implies
11133 that, when a package is changed, @emph{every package that depends on it}
11134 must be rebuilt. This can significantly slow down the deployment of
11135 fixes in core packages such as libc or Bash, since basically the whole
11136 distribution would need to be rebuilt. Using pre-built binaries helps
11137 (@pxref{Substitutes}), but deployment may still take more time than
11141 To address this, Guix implements @dfn{grafts}, a mechanism that allows
11142 for fast deployment of critical updates without the costs associated
11143 with a whole-distribution rebuild. The idea is to rebuild only the
11144 package that needs to be patched, and then to ``graft'' it onto packages
11145 explicitly installed by the user and that were previously referring to
11146 the original package. The cost of grafting is typically very low, and
11147 order of magnitudes lower than a full rebuild of the dependency chain.
11149 @cindex replacements of packages, for grafts
11150 For instance, suppose a security update needs to be applied to Bash.
11151 Guix developers will provide a package definition for the ``fixed''
11152 Bash, say @var{bash-fixed}, in the usual way (@pxref{Defining
11153 Packages}). Then, the original package definition is augmented with a
11154 @code{replacement} field pointing to the package containing the bug fix:
11161 (replacement bash-fixed)))
11164 From there on, any package depending directly or indirectly on Bash---as
11165 reported by @command{guix gc --requisites} (@pxref{Invoking guix
11166 gc})---that is installed is automatically ``rewritten'' to refer to
11167 @var{bash-fixed} instead of @var{bash}. This grafting process takes
11168 time proportional to the size of the package, usually less than a
11169 minute for an ``average'' package on a recent machine. Grafting is
11170 recursive: when an indirect dependency requires grafting, then grafting
11171 ``propagates'' up to the package that the user is installing.
11173 Currently, the graft and the package it replaces (@var{bash-fixed} and
11174 @var{bash} in the example above) must have the exact same @code{name}
11175 and @code{version} fields. This restriction mostly comes from the fact
11176 that grafting works by patching files, including binary files, directly.
11177 Other restrictions may apply: for instance, when adding a graft to a
11178 package providing a shared library, the original shared library and its
11179 replacement must have the same @code{SONAME} and be binary-compatible.
11181 The @option{--no-grafts} command-line option allows you to forcefully
11182 avoid grafting (@pxref{Common Build Options, @option{--no-grafts}}).
11186 guix build bash --no-grafts
11190 returns the store file name of the original Bash, whereas:
11197 returns the store file name of the ``fixed'', replacement Bash. This
11198 allows you to distinguish between the two variants of Bash.
11200 To verify which Bash your whole profile refers to, you can run
11201 (@pxref{Invoking guix gc}):
11204 guix gc -R `readlink -f ~/.guix-profile` | grep bash
11208 @dots{} and compare the store file names that you get with those above.
11209 Likewise for a complete GuixSD system generation:
11212 guix gc -R `guix system build my-config.scm` | grep bash
11215 Lastly, to check which Bash running processes are using, you can use the
11216 @command{lsof} command:
11219 lsof | grep /gnu/store/.*bash
11223 @node Package Modules
11224 @section Package Modules
11226 From a programming viewpoint, the package definitions of the
11227 GNU distribution are provided by Guile modules in the @code{(gnu packages
11228 @dots{})} name space@footnote{Note that packages under the @code{(gnu
11229 packages @dots{})} module name space are not necessarily ``GNU
11230 packages''. This module naming scheme follows the usual Guile module
11231 naming convention: @code{gnu} means that these modules are distributed
11232 as part of the GNU system, and @code{packages} identifies modules that
11233 define packages.} (@pxref{Modules, Guile modules,, guile, GNU Guile
11234 Reference Manual}). For instance, the @code{(gnu packages emacs)}
11235 module exports a variable named @code{emacs}, which is bound to a
11236 @code{<package>} object (@pxref{Defining Packages}).
11238 The @code{(gnu packages @dots{})} module name space is
11239 automatically scanned for packages by the command-line tools. For
11240 instance, when running @code{guix package -i emacs}, all the @code{(gnu
11241 packages @dots{})} modules are scanned until one that exports a package
11242 object whose name is @code{emacs} is found. This package search
11243 facility is implemented in the @code{(gnu packages)} module.
11245 @cindex customization, of packages
11246 @cindex package module search path
11247 Users can store package definitions in modules with different
11248 names---e.g., @code{(my-packages emacs)}@footnote{Note that the file
11249 name and module name must match. For instance, the @code{(my-packages
11250 emacs)} module must be stored in a @file{my-packages/emacs.scm} file
11251 relative to the load path specified with @option{--load-path} or
11252 @code{GUIX_PACKAGE_PATH}. @xref{Modules and the File System,,,
11253 guile, GNU Guile Reference Manual}, for details.}. These package definitions
11254 will not be visible by default. Users can invoke commands such as
11255 @command{guix package} and @command{guix build} with the
11256 @code{-e} option so that they know where to find the package. Better
11257 yet, they can use the
11258 @code{-L} option of these commands to make those modules visible
11259 (@pxref{Invoking guix build, @code{--load-path}}), or define the
11260 @code{GUIX_PACKAGE_PATH} environment variable. This environment
11261 variable makes it easy to extend or customize the distribution and is
11262 honored by all the user interfaces.
11264 @defvr {Environment Variable} GUIX_PACKAGE_PATH
11265 This is a colon-separated list of directories to search for additional
11266 package modules. Directories listed in this variable take precedence
11267 over the own modules of the distribution.
11270 The distribution is fully @dfn{bootstrapped} and @dfn{self-contained}:
11271 each package is built based solely on other packages in the
11272 distribution. The root of this dependency graph is a small set of
11273 @dfn{bootstrap binaries}, provided by the @code{(gnu packages
11274 bootstrap)} module. For more information on bootstrapping,
11275 @pxref{Bootstrapping}.
11277 @node Packaging Guidelines
11278 @section Packaging Guidelines
11280 The GNU distribution is nascent and may well lack some of your favorite
11281 packages. This section describes how you can help make the distribution
11282 grow. @xref{Contributing}, for additional information on how you can
11285 Free software packages are usually distributed in the form of
11286 @dfn{source code tarballs}---typically @file{tar.gz} files that contain
11287 all the source files. Adding a package to the distribution means
11288 essentially two things: adding a @dfn{recipe} that describes how to
11289 build the package, including a list of other packages required to build
11290 it, and adding @dfn{package metadata} along with that recipe, such as a
11291 description and licensing information.
11293 In Guix all this information is embodied in @dfn{package definitions}.
11294 Package definitions provide a high-level view of the package. They are
11295 written using the syntax of the Scheme programming language; in fact,
11296 for each package we define a variable bound to the package definition,
11297 and export that variable from a module (@pxref{Package Modules}).
11298 However, in-depth Scheme knowledge is @emph{not} a prerequisite for
11299 creating packages. For more information on package definitions,
11300 @pxref{Defining Packages}.
11302 Once a package definition is in place, stored in a file in the Guix
11303 source tree, it can be tested using the @command{guix build} command
11304 (@pxref{Invoking guix build}). For example, assuming the new package is
11305 called @code{gnew}, you may run this command from the Guix build tree
11306 (@pxref{Running Guix Before It Is Installed}):
11309 ./pre-inst-env guix build gnew --keep-failed
11312 Using @code{--keep-failed} makes it easier to debug build failures since
11313 it provides access to the failed build tree. Another useful
11314 command-line option when debugging is @code{--log-file}, to access the
11317 If the package is unknown to the @command{guix} command, it may be that
11318 the source file contains a syntax error, or lacks a @code{define-public}
11319 clause to export the package variable. To figure it out, you may load
11320 the module from Guile to get more information about the actual error:
11323 ./pre-inst-env guile -c '(use-modules (gnu packages gnew))'
11326 Once your package builds correctly, please send us a patch
11327 (@pxref{Contributing}). Well, if you need help, we will be happy to
11328 help you too. Once the patch is committed in the Guix repository, the
11329 new package automatically gets built on the supported platforms by
11330 @url{http://hydra.gnu.org/jobset/gnu/master, our continuous integration
11333 @cindex substituter
11334 Users can obtain the new package definition simply by running
11335 @command{guix pull} (@pxref{Invoking guix pull}). When
11336 @code{hydra.gnu.org} is done building the package, installing the
11337 package automatically downloads binaries from there
11338 (@pxref{Substitutes}). The only place where human intervention is
11339 needed is to review and apply the patch.
11343 * Software Freedom:: What may go into the distribution.
11344 * Package Naming:: What's in a name?
11345 * Version Numbers:: When the name is not enough.
11346 * Synopses and Descriptions:: Helping users find the right package.
11347 * Python Modules:: Taming the snake.
11348 * Perl Modules:: Little pearls.
11349 * Java Packages:: Coffee break.
11350 * Fonts:: Fond of fonts.
11353 @node Software Freedom
11354 @subsection Software Freedom
11356 @c Adapted from http://www.gnu.org/philosophy/philosophy.html.
11358 The GNU operating system has been developed so that users can have
11359 freedom in their computing. GNU is @dfn{free software}, meaning that
11360 users have the @url{http://www.gnu.org/philosophy/free-sw.html,four
11361 essential freedoms}: to run the program, to study and change the program
11362 in source code form, to redistribute exact copies, and to distribute
11363 modified versions. Packages found in the GNU distribution provide only
11364 software that conveys these four freedoms.
11366 In addition, the GNU distribution follow the
11367 @url{http://www.gnu.org/distros/free-system-distribution-guidelines.html,free
11368 software distribution guidelines}. Among other things, these guidelines
11369 reject non-free firmware, recommendations of non-free software, and
11370 discuss ways to deal with trademarks and patents.
11372 Some otherwise free upstream package sources contain a small and optional
11373 subset that violates the above guidelines, for instance because this subset
11374 is itself non-free code. When that happens, the offending items are removed
11375 with appropriate patches or code snippets in the @code{origin} form of the
11376 package (@pxref{Defining Packages}). This way, @code{guix
11377 build --source} returns the ``freed'' source rather than the unmodified
11381 @node Package Naming
11382 @subsection Package Naming
11384 A package has actually two names associated with it:
11385 First, there is the name of the @emph{Scheme variable}, the one following
11386 @code{define-public}. By this name, the package can be made known in the
11387 Scheme code, for instance as input to another package. Second, there is
11388 the string in the @code{name} field of a package definition. This name
11389 is used by package management commands such as
11390 @command{guix package} and @command{guix build}.
11392 Both are usually the same and correspond to the lowercase conversion of
11393 the project name chosen upstream, with underscores replaced with
11394 hyphens. For instance, GNUnet is available as @code{gnunet}, and
11395 SDL_net as @code{sdl-net}.
11397 We do not add @code{lib} prefixes for library packages, unless these are
11398 already part of the official project name. But @pxref{Python
11399 Modules} and @ref{Perl Modules} for special rules concerning modules for
11400 the Python and Perl languages.
11402 Font package names are handled differently, @pxref{Fonts}.
11405 @node Version Numbers
11406 @subsection Version Numbers
11408 We usually package only the latest version of a given free software
11409 project. But sometimes, for instance for incompatible library versions,
11410 two (or more) versions of the same package are needed. These require
11411 different Scheme variable names. We use the name as defined
11412 in @ref{Package Naming}
11413 for the most recent version; previous versions use the same name, suffixed
11414 by @code{-} and the smallest prefix of the version number that may
11415 distinguish the two versions.
11417 The name inside the package definition is the same for all versions of a
11418 package and does not contain any version number.
11420 For instance, the versions 2.24.20 and 3.9.12 of GTK+ may be packaged as follows:
11423 (define-public gtk+
11428 (define-public gtk+-2
11431 (version "2.24.20")
11434 If we also wanted GTK+ 3.8.2, this would be packaged as
11436 (define-public gtk+-3.8
11443 @c See <https://lists.gnu.org/archive/html/guix-devel/2016-01/msg00425.html>,
11444 @c for a discussion of what follows.
11445 @cindex version number, for VCS snapshots
11446 Occasionally, we package snapshots of upstream's version control system
11447 (VCS) instead of formal releases. This should remain exceptional,
11448 because it is up to upstream developers to clarify what the stable
11449 release is. Yet, it is sometimes necessary. So, what should we put in
11450 the @code{version} field?
11452 Clearly, we need to make the commit identifier of the VCS snapshot
11453 visible in the version string, but we also need to make sure that the
11454 version string is monotonically increasing so that @command{guix package
11455 --upgrade} can determine which version is newer. Since commit
11456 identifiers, notably with Git, are not monotonically increasing, we add
11457 a revision number that we increase each time we upgrade to a newer
11458 snapshot. The resulting version string looks like this:
11463 | | `-- upstream commit ID
11465 | `--- Guix package revision
11467 latest upstream version
11470 It is a good idea to strip commit identifiers in the @code{version}
11471 field to, say, 7 digits. It avoids an aesthetic annoyance (assuming
11472 aesthetics have a role to play here) as well as problems related to OS
11473 limits such as the maximum shebang length (127 bytes for the Linux
11474 kernel.) It is best to use the full commit identifiers in
11475 @code{origin}s, though, to avoid ambiguities. A typical package
11476 definition may look like this:
11480 (let ((commit "c3f29bc928d5900971f65965feaae59e1272a3f7"))
11482 (version (string-append "0.9-1."
11483 (string-take commit 7)))
11486 (uri (git-reference
11487 (url "git://example.org/my-package.git")
11489 (sha256 (base32 "1mbikn@dots{}"))
11490 (file-name (string-append "my-package-" version
11496 @node Synopses and Descriptions
11497 @subsection Synopses and Descriptions
11499 As we have seen before, each package in GNU@tie{}Guix includes a
11500 synopsis and a description (@pxref{Defining Packages}). Synopses and
11501 descriptions are important: They are what @command{guix package
11502 --search} searches, and a crucial piece of information to help users
11503 determine whether a given package suits their needs. Consequently,
11504 packagers should pay attention to what goes into them.
11506 Synopses must start with a capital letter and must not end with a
11507 period. They must not start with ``a'' or ``the'', which usually does
11508 not bring anything; for instance, prefer ``File-frobbing tool'' over ``A
11509 tool that frobs files''. The synopsis should say what the package
11510 is---e.g., ``Core GNU utilities (file, text, shell)''---or what it is
11511 used for---e.g., the synopsis for GNU@tie{}grep is ``Print lines
11512 matching a pattern''.
11514 Keep in mind that the synopsis must be meaningful for a very wide
11515 audience. For example, ``Manipulate alignments in the SAM format''
11516 might make sense for a seasoned bioinformatics researcher, but might be
11517 fairly unhelpful or even misleading to a non-specialized audience. It
11518 is a good idea to come up with a synopsis that gives an idea of the
11519 application domain of the package. In this example, this might give
11520 something like ``Manipulate nucleotide sequence alignments'', which
11521 hopefully gives the user a better idea of whether this is what they are
11524 Descriptions should take between five and ten lines. Use full
11525 sentences, and avoid using acronyms without first introducing them.
11526 Please avoid marketing phrases such as ``world-leading'',
11527 ``industrial-strength'', and ``next-generation'', and avoid superlatives
11528 like ``the most advanced''---they are not helpful to users looking for a
11529 package and may even sound suspicious. Instead, try to be factual,
11530 mentioning use cases and features.
11532 @cindex Texinfo markup, in package descriptions
11533 Descriptions can include Texinfo markup, which is useful to introduce
11534 ornaments such as @code{@@code} or @code{@@dfn}, bullet lists, or
11535 hyperlinks (@pxref{Overview,,, texinfo, GNU Texinfo}). However you
11536 should be careful when using some characters for example @samp{@@} and
11537 curly braces which are the basic special characters in Texinfo
11538 (@pxref{Special Characters,,, texinfo, GNU Texinfo}). User interfaces
11539 such as @command{guix package --show} take care of rendering it
11542 Synopses and descriptions are translated by volunteers
11543 @uref{http://translationproject.org/domain/guix-packages.html, at the
11544 Translation Project} so that as many users as possible can read them in
11545 their native language. User interfaces search them and display them in
11546 the language specified by the current locale.
11548 Translation is a lot of work so, as a packager, please pay even more
11549 attention to your synopses and descriptions as every change may entail
11550 additional work for translators. In order to help them, it is possible
11551 to make recommendations or instructions visible to them by inserting
11552 special comments like this (@pxref{xgettext Invocation,,, gettext, GNU
11556 ;; TRANSLATORS: "X11 resize-and-rotate" should not be translated.
11557 (description "ARandR is designed to provide a simple visual front end
11558 for the X11 resize-and-rotate (RandR) extension. @dots{}")
11562 @node Python Modules
11563 @subsection Python Modules
11565 We currently package Python 2 and Python 3, under the Scheme variable names
11566 @code{python-2} and @code{python} as explained in @ref{Version Numbers}.
11567 To avoid confusion and naming clashes with other programming languages, it
11568 seems desirable that the name of a package for a Python module contains
11569 the word @code{python}.
11571 Some modules are compatible with only one version of Python, others with both.
11572 If the package Foo compiles only with Python 3, we name it
11573 @code{python-foo}; if it compiles only with Python 2, we name it
11574 @code{python2-foo}. If it is compatible with both versions, we create two
11575 packages with the corresponding names.
11577 If a project already contains the word @code{python}, we drop this;
11578 for instance, the module python-dateutil is packaged under the names
11579 @code{python-dateutil} and @code{python2-dateutil}. If the project name
11580 starts with @code{py} (e.g. @code{pytz}), we keep it and prefix it as
11585 @subsection Perl Modules
11587 Perl programs standing for themselves are named as any other package,
11588 using the lowercase upstream name.
11589 For Perl packages containing a single class, we use the lowercase class name,
11590 replace all occurrences of @code{::} by dashes and prepend the prefix
11592 So the class @code{XML::Parser} becomes @code{perl-xml-parser}.
11593 Modules containing several classes keep their lowercase upstream name and
11594 are also prepended by @code{perl-}. Such modules tend to have the word
11595 @code{perl} somewhere in their name, which gets dropped in favor of the
11596 prefix. For instance, @code{libwww-perl} becomes @code{perl-libwww}.
11599 @node Java Packages
11600 @subsection Java Packages
11602 Java programs standing for themselves are named as any other package,
11603 using the lowercase upstream name.
11605 To avoid confusion and naming clashes with other programming languages,
11606 it is desirable that the name of a package for a Java package is
11607 prefixed with @code{java-}. If a project already contains the word
11608 @code{java}, we drop this; for instance, the package @code{ngsjava} is
11609 packaged under the name @code{java-ngs}.
11611 For Java packages containing a single class or a small class hierarchy,
11612 we use the lowercase class name, replace all occurrences of @code{.} by
11613 dashes and prepend the prefix @code{java-}. So the class
11614 @code{apache.commons.cli} becomes package
11615 @code{java-apache-commons-cli}.
11621 For fonts that are in general not installed by a user for typesetting
11622 purposes, or that are distributed as part of a larger software package,
11623 we rely on the general packaging rules for software; for instance, this
11624 applies to the fonts delivered as part of the X.Org system or fonts that
11625 are part of TeX Live.
11627 To make it easier for a user to search for fonts, names for other packages
11628 containing only fonts are constructed as follows, independently of the
11629 upstream package name.
11631 The name of a package containing only one font family starts with
11632 @code{font-}; it is followed by the foundry name and a dash @code{-}
11633 if the foundry is known, and the font family name, in which spaces are
11634 replaced by dashes (and as usual, all upper case letters are transformed
11636 For example, the Gentium font family by SIL is packaged under the name
11637 @code{font-sil-gentium}.
11639 For a package containing several font families, the name of the collection
11640 is used in the place of the font family name.
11641 For instance, the Liberation fonts consist of three families,
11642 Liberation Sans, Liberation Serif and Liberation Mono.
11643 These could be packaged separately under the names
11644 @code{font-liberation-sans} and so on; but as they are distributed together
11645 under a common name, we prefer to package them together as
11646 @code{font-liberation}.
11648 In the case where several formats of the same font family or font collection
11649 are packaged separately, a short form of the format, prepended by a dash,
11650 is added to the package name. We use @code{-ttf} for TrueType fonts,
11651 @code{-otf} for OpenType fonts and @code{-type1} for PostScript Type 1
11656 @node Bootstrapping
11657 @section Bootstrapping
11659 @c Adapted from the ELS 2013 paper.
11661 @cindex bootstrapping
11663 Bootstrapping in our context refers to how the distribution gets built
11664 ``from nothing''. Remember that the build environment of a derivation
11665 contains nothing but its declared inputs (@pxref{Introduction}). So
11666 there's an obvious chicken-and-egg problem: how does the first package
11667 get built? How does the first compiler get compiled? Note that this is
11668 a question of interest only to the curious hacker, not to the regular
11669 user, so you can shamelessly skip this section if you consider yourself
11670 a ``regular user''.
11672 @cindex bootstrap binaries
11673 The GNU system is primarily made of C code, with libc at its core. The
11674 GNU build system itself assumes the availability of a Bourne shell and
11675 command-line tools provided by GNU Coreutils, Awk, Findutils, `sed', and
11676 `grep'. Furthermore, build programs---programs that run
11677 @code{./configure}, @code{make}, etc.---are written in Guile Scheme
11678 (@pxref{Derivations}). Consequently, to be able to build anything at
11679 all, from scratch, Guix relies on pre-built binaries of Guile, GCC,
11680 Binutils, libc, and the other packages mentioned above---the
11681 @dfn{bootstrap binaries}.
11683 These bootstrap binaries are ``taken for granted'', though we can also
11684 re-create them if needed (more on that later).
11686 @unnumberedsubsec Preparing to Use the Bootstrap Binaries
11688 @c As of Emacs 24.3, Info-mode displays the image, but since it's a
11689 @c large image, it's hard to scroll. Oh well.
11690 @image{images/bootstrap-graph,6in,,Dependency graph of the early bootstrap derivations}
11692 The figure above shows the very beginning of the dependency graph of the
11693 distribution, corresponding to the package definitions of the @code{(gnu
11694 packages bootstrap)} module. A similar figure can be generated with
11695 @command{guix graph} (@pxref{Invoking guix graph}), along the lines of:
11698 guix graph -t derivation \
11699 -e '(@@@@ (gnu packages bootstrap) %bootstrap-gcc)' \
11703 At this level of detail, things are
11704 slightly complex. First, Guile itself consists of an ELF executable,
11705 along with many source and compiled Scheme files that are dynamically
11706 loaded when it runs. This gets stored in the @file{guile-2.0.7.tar.xz}
11707 tarball shown in this graph. This tarball is part of Guix's ``source''
11708 distribution, and gets inserted into the store with @code{add-to-store}
11709 (@pxref{The Store}).
11711 But how do we write a derivation that unpacks this tarball and adds it
11712 to the store? To solve this problem, the @code{guile-bootstrap-2.0.drv}
11713 derivation---the first one that gets built---uses @code{bash} as its
11714 builder, which runs @code{build-bootstrap-guile.sh}, which in turn calls
11715 @code{tar} to unpack the tarball. Thus, @file{bash}, @file{tar},
11716 @file{xz}, and @file{mkdir} are statically-linked binaries, also part of
11717 the Guix source distribution, whose sole purpose is to allow the Guile
11718 tarball to be unpacked.
11720 Once @code{guile-bootstrap-2.0.drv} is built, we have a functioning
11721 Guile that can be used to run subsequent build programs. Its first task
11722 is to download tarballs containing the other pre-built binaries---this
11723 is what the @code{.tar.xz.drv} derivations do. Guix modules such as
11724 @code{ftp-client.scm} are used for this purpose. The
11725 @code{module-import.drv} derivations import those modules in a directory
11726 in the store, using the original layout. The
11727 @code{module-import-compiled.drv} derivations compile those modules, and
11728 write them in an output directory with the right layout. This
11729 corresponds to the @code{#:modules} argument of
11730 @code{build-expression->derivation} (@pxref{Derivations}).
11732 Finally, the various tarballs are unpacked by the
11733 derivations @code{gcc-bootstrap-0.drv}, @code{glibc-bootstrap-0.drv},
11734 etc., at which point we have a working C tool chain.
11737 @unnumberedsubsec Building the Build Tools
11739 Bootstrapping is complete when we have a full tool chain that does not
11740 depend on the pre-built bootstrap tools discussed above. This
11741 no-dependency requirement is verified by checking whether the files of
11742 the final tool chain contain references to the @file{/gnu/store}
11743 directories of the bootstrap inputs. The process that leads to this
11744 ``final'' tool chain is described by the package definitions found in
11745 the @code{(gnu packages commencement)} module.
11747 The @command{guix graph} command allows us to ``zoom out'' compared to
11748 the graph above, by looking at the level of package objects instead of
11749 individual derivations---remember that a package may translate to
11750 several derivations, typically one derivation to download its source,
11751 one to build the Guile modules it needs, and one to actually build the
11752 package from source. The command:
11755 guix graph -t bag \
11756 -e '(@@@@ (gnu packages commencement)
11757 glibc-final-with-bootstrap-bash)' | dot -Tps > t.ps
11761 produces the dependency graph leading to the ``final'' C
11762 library@footnote{You may notice the @code{glibc-intermediate} label,
11763 suggesting that it is not @emph{quite} final, but as a good
11764 approximation, we will consider it final.}, depicted below.
11766 @image{images/bootstrap-packages,6in,,Dependency graph of the early packages}
11768 @c See <http://lists.gnu.org/archive/html/gnu-system-discuss/2012-10/msg00000.html>.
11769 The first tool that gets built with the bootstrap binaries is
11770 GNU@tie{}Make---noted @code{make-boot0} above---which is a prerequisite
11771 for all the following packages. From there Findutils and Diffutils get
11774 Then come the first-stage Binutils and GCC, built as pseudo cross
11775 tools---i.e., with @code{--target} equal to @code{--host}. They are
11776 used to build libc. Thanks to this cross-build trick, this libc is
11777 guaranteed not to hold any reference to the initial tool chain.
11779 From there the final Binutils and GCC (not shown above) are built.
11781 from the final Binutils, and links programs against the just-built libc.
11782 This tool chain is used to build the other packages used by Guix and by
11783 the GNU Build System: Guile, Bash, Coreutils, etc.
11785 And voilà! At this point we have the complete set of build tools that
11786 the GNU Build System expects. These are in the @code{%final-inputs}
11787 variable of the @code{(gnu packages commencement)} module, and are
11788 implicitly used by any package that uses @code{gnu-build-system}
11789 (@pxref{Build Systems, @code{gnu-build-system}}).
11792 @unnumberedsubsec Building the Bootstrap Binaries
11794 Because the final tool chain does not depend on the bootstrap binaries,
11795 those rarely need to be updated. Nevertheless, it is useful to have an
11796 automated way to produce them, should an update occur, and this is what
11797 the @code{(gnu packages make-bootstrap)} module provides.
11799 The following command builds the tarballs containing the bootstrap
11800 binaries (Guile, Binutils, GCC, libc, and a tarball containing a mixture
11801 of Coreutils and other basic command-line tools):
11804 guix build bootstrap-tarballs
11807 The generated tarballs are those that should be referred to in the
11808 @code{(gnu packages bootstrap)} module mentioned at the beginning of
11811 Still here? Then perhaps by now you've started to wonder: when do we
11812 reach a fixed point? That is an interesting question! The answer is
11813 unknown, but if you would like to investigate further (and have
11814 significant computational and storage resources to do so), then let us
11818 @section Porting to a New Platform
11820 As discussed above, the GNU distribution is self-contained, and
11821 self-containment is achieved by relying on pre-built ``bootstrap
11822 binaries'' (@pxref{Bootstrapping}). These binaries are specific to an
11823 operating system kernel, CPU architecture, and application binary
11824 interface (ABI). Thus, to port the distribution to a platform that is
11825 not yet supported, one must build those bootstrap binaries, and update
11826 the @code{(gnu packages bootstrap)} module to use them on that platform.
11828 Fortunately, Guix can @emph{cross compile} those bootstrap binaries.
11829 When everything goes well, and assuming the GNU tool chain supports the
11830 target platform, this can be as simple as running a command like this
11834 guix build --target=armv5tel-linux-gnueabi bootstrap-tarballs
11837 For this to work, the @code{glibc-dynamic-linker} procedure in
11838 @code{(gnu packages bootstrap)} must be augmented to return the right
11839 file name for libc's dynamic linker on that platform; likewise,
11840 @code{system->linux-architecture} in @code{(gnu packages linux)} must be
11841 taught about the new platform.
11843 Once these are built, the @code{(gnu packages bootstrap)} module needs
11844 to be updated to refer to these binaries on the target platform. That
11845 is, the hashes and URLs of the bootstrap tarballs for the new platform
11846 must be added alongside those of the currently supported platforms. The
11847 bootstrap Guile tarball is treated specially: it is expected to be
11848 available locally, and @file{gnu/local.mk} has rules do download it for
11849 the supported architectures; a rule for the new platform must be added
11852 In practice, there may be some complications. First, it may be that the
11853 extended GNU triplet that specifies an ABI (like the @code{eabi} suffix
11854 above) is not recognized by all the GNU tools. Typically, glibc
11855 recognizes some of these, whereas GCC uses an extra @code{--with-abi}
11856 configure flag (see @code{gcc.scm} for examples of how to handle this).
11857 Second, some of the required packages could fail to build for that
11858 platform. Lastly, the generated binaries could be broken for some
11861 @c *********************************************************************
11862 @include contributing.texi
11864 @c *********************************************************************
11865 @node Acknowledgments
11866 @chapter Acknowledgments
11868 Guix is based on the @uref{http://nixos.org/nix/, Nix package manager},
11869 which was designed and
11870 implemented by Eelco Dolstra, with contributions from other people (see
11871 the @file{nix/AUTHORS} file in Guix.) Nix pioneered functional package
11872 management, and promoted unprecedented features, such as transactional
11873 package upgrades and rollbacks, per-user profiles, and referentially
11874 transparent build processes. Without this work, Guix would not exist.
11876 The Nix-based software distributions, Nixpkgs and NixOS, have also been
11877 an inspiration for Guix.
11879 GNU@tie{}Guix itself is a collective work with contributions from a
11880 number of people. See the @file{AUTHORS} file in Guix for more
11881 information on these fine people. The @file{THANKS} file lists people
11882 who have helped by reporting bugs, taking care of the infrastructure,
11883 providing artwork and themes, making suggestions, and more---thank you!
11886 @c *********************************************************************
11887 @node GNU Free Documentation License
11888 @appendix GNU Free Documentation License
11890 @include fdl-1.3.texi
11892 @c *********************************************************************
11893 @node Concept Index
11894 @unnumbered Concept Index
11897 @node Programming Index
11898 @unnumbered Programming Index
11899 @syncodeindex tp fn
11900 @syncodeindex vr fn
11905 @c Local Variables:
11906 @c ispell-local-dictionary: "american";