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\input texinfo
@c -*-texinfo-*-
@c %**start of header
@setfilename guix.info
@documentencoding UTF-8
@c %**end of header
@include version.texi
@c Identifier of the OpenPGP key used to sign tarballs and such.
@set OPENPGP-SIGNING-KEY-ID 3CE464558A84FDC69DB40CFB090B11993D9AEBB5
Copyright @copyright{} 2012, 2013, 2014, 2015, 2016, 2017 Ludovic Courtès@*
Copyright @copyright{} 2013, 2014, 2016 Andreas Enge@*
Taylan Ulrich Bayırlı/Kammer
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Copyright @copyright{} 2013 Nikita Karetnikov@*
Copyright @copyright{} 2014, 2015, 2016 Alex Kost@*
Copyright @copyright{} 2015, 2016 Mathieu Lirzin@*
Copyright @copyright{} 2014 Pierre-Antoine Rault@*
Copyright @copyright{} 2015 Taylan Ulrich Bayırlı/Kammer@*
Copyright @copyright{} 2015, 2016, 2017 Leo Famulari@*
Copyright @copyright{} 2015, 2016, 2017 Ricardo Wurmus@*
Copyright @copyright{} 2016 Ben Woodcroft@*
Copyright @copyright{} 2016 Chris Marusich@*
Copyright @copyright{} 2016, 2017 Efraim Flashner@*
Copyright @copyright{} 2016 John Darrington@*
Copyright @copyright{} 2016, 2017 Jan Nieuwenhuizen@*
Copyright @copyright{} 2016 Julien Lepiller@*
Copyright @copyright{} 2016 Alex ter Weele@*
Copyright @copyright{} 2017 Clément Lassieur@*
Copyright @copyright{} 2017 Mathieu Othacehe@*
Copyright @copyright{} 2017 Federico Beffa@*
Copyright @copyright{} 2017 Carlo Zancanaro@*
Copyright @copyright{} 2017 Thomas Danckaert@*
Copyright @copyright{} 2017 humanitiesNerd@*
Copyright @copyright{} 2017 Christopher Allan Webber@*
Copyright @copyright{} 2017 Marius Bakke@*
Copyright @copyright{} 2017 Hartmut Goebel@*
Copyright @copyright{} 2017 Maxim Cournoyer@*
Copyright @copyright{} 2017 Tobias Geerinckx-Rice
Permission is granted to copy, distribute and/or modify this document
under the terms of the GNU Free Documentation License, Version 1.3 or
any later version published by the Free Software Foundation; with no
Invariant Sections, no Front-Cover Texts, and no Back-Cover Texts. A
copy of the license is included in the section entitled ``GNU Free
Documentation License''.
@end copying
* Guix: (guix). Manage installed software and system configuration.
* guix package: (guix)Invoking guix package. Installing, removing, and upgrading packages.
* guix gc: (guix)Invoking guix gc. Reclaiming unused disk space.
* guix pull: (guix)Invoking guix pull. Update the list of available packages.
* guix system: (guix)Invoking guix system. Manage the operating system configuration.
@dircategory Software development
@direntry
* guix environment: (guix)Invoking guix environment. Building development environments with Guix.
* guix build: (guix)Invoking guix build. Building packages.
* guix pack: (guix)Invoking guix pack. Creating binary bundles.
@title GNU Guix Reference Manual
@subtitle Using the GNU Guix Functional Package Manager
@author The GNU Guix Developers
@page
@vskip 0pt plus 1filll
Edition @value{EDITION} @*
@value{UPDATED} @*
@end titlepage
@contents
@c *********************************************************************
@node Top
This document describes GNU Guix version @value{VERSION}, a functional
package management tool written for the GNU system.
@menu
* Introduction:: What is Guix about?
* Installation:: Installing Guix.
* Package Management:: Package installation, upgrade, etc.
* Programming Interface:: Using Guix in Scheme.
* Utilities:: Package management commands.
* GNU Distribution:: Software for your friendly GNU system.
* Contributing:: Your help needed!
* Acknowledgments:: Thanks!
* GNU Free Documentation License:: The license of this manual.
* Concept Index:: Concepts.
* Programming Index:: Data types, functions, and variables.
@detailmenu
--- The Detailed Node Listing ---
Installation
* Binary Installation:: Getting Guix running in no time!
* Requirements:: Software needed to build and run Guix.
* Running the Test Suite:: Testing Guix.
* Setting Up the Daemon:: Preparing the build daemon's environment.
* Invoking guix-daemon:: Running the build daemon.
* Application Setup:: Application-specific setup.
Setting Up the Daemon
* Build Environment Setup:: Preparing the isolated build environment.
* Daemon Offload Setup:: Offloading builds to remote machines.
Package Management
* Features:: How Guix will make your life brighter.
* Invoking guix package:: Package installation, removal, etc.
* Substitutes:: Downloading pre-built binaries.
* Packages with Multiple Outputs:: Single source package, multiple outputs.
* Invoking guix gc:: Running the garbage collector.
* Invoking guix pull:: Fetching the latest Guix and distribution.
* Invoking guix archive:: Exporting and importing store files.
Programming Interface
* Defining Packages:: Defining new packages.
* Build Systems:: Specifying how packages are built.
* The Store:: Manipulating the package store.
* Derivations:: Low-level interface to package derivations.
* The Store Monad:: Purely functional interface to the store.
* G-Expressions:: Manipulating build expressions.
* package Reference :: The package data type.
* origin Reference:: The origin data type.
Utilities
* Invoking guix build:: Building packages from the command line.
* Invoking guix download:: Downloading a file and printing its hash.
* Invoking guix hash:: Computing the cryptographic hash of a file.
* Invoking guix import:: Importing package definitions.
* Invoking guix refresh:: Updating package definitions.
* Invoking guix lint:: Finding errors in package definitions.
* Invoking guix graph:: Visualizing the graph of packages.
* Invoking guix environment:: Setting up development environments.
* Invoking guix publish:: Sharing substitutes.
* Invoking guix challenge:: Challenging substitute servers.
* Invoking guix copy:: Copying to and from a remote store.
* Invoking guix container:: Process isolation.
* Invoking guix weather:: Assessing substitute availability.
Invoking @command{guix build}
* Common Build Options:: Build options for most commands.
* Package Transformation Options:: Creating variants of packages.
* Additional Build Options:: Options specific to 'guix build'.
* Debugging Build Failures:: Real life packaging experience.
GNU Distribution
* System Installation:: Installing the whole operating system.
* System Configuration:: Configuring the operating system.
* Documentation:: Browsing software user manuals.
* Installing Debugging Files:: Feeding the debugger.
* Security Updates:: Deploying security fixes quickly.
* Package Modules:: Packages from the programmer's viewpoint.
* Packaging Guidelines:: Growing the distribution.
* Bootstrapping:: GNU/Linux built from scratch.
* Porting:: Targeting another platform or kernel.
System Installation
* Limitations:: What you can expect.
* Hardware Considerations:: Supported hardware.
* USB Stick Installation:: Preparing the installation medium.
* Preparing for Installation:: Networking, partitioning, etc.
* Proceeding with the Installation:: The real thing.
* Installing GuixSD in a VM:: GuixSD playground.
* Building the Installation Image:: How this comes to be.
System Configuration
* Using the Configuration System:: Customizing your GNU system.
* operating-system Reference:: Detail of operating-system declarations.
* File Systems:: Configuring file system mounts.
* Mapped Devices:: Block device extra processing.
* User Accounts:: Specifying user accounts.
* Locales:: Language and cultural convention settings.
* Services:: Specifying system services.
* Setuid Programs:: Programs running with root privileges.
* X.509 Certificates:: Authenticating HTTPS servers.
* Name Service Switch:: Configuring libc's name service switch.
* Initial RAM Disk:: Linux-Libre bootstrapping.
* Bootloader Configuration:: Configuring the boot loader.
* Invoking guix system:: Instantiating a system configuration.
* Running GuixSD in a VM:: How to run GuixSD in a virtual machine.
* Defining Services:: Adding new service definitions.
Services
* Base Services:: Essential system services.
* Scheduled Job Execution:: The mcron service.
* Networking Services:: Network setup, SSH daemon, etc.
* X Window:: Graphical display.
* Printing Services:: Local and remote printer support.
* Desktop Services:: D-Bus and desktop services.
* Database Services:: SQL databases, key-value stores, etc.
* Monitoring Services:: Monitoring services.
* Web Services:: Web servers.
* Network File System:: NFS related services.
* Virtualization Services:: Virtualization services.
* Miscellaneous Services:: Other services.
Defining Services
* Service Composition:: The model for composing services.
* Service Types and Services:: Types and services.
* Service Reference:: API reference.
* Shepherd Services:: A particular type of service.
* Software Freedom:: What may go into the distribution.
* Package Naming:: What's in a name?
* Version Numbers:: When the name is not enough.
* Synopses and Descriptions:: Helping users find the right package.
* Python Modules:: A touch of British comedy.
* Perl Modules:: Little pearls.
* Java Packages:: Coffee break.
Contributing
* Building from Git:: The latest and greatest.
* Running Guix Before It Is Installed:: Hacker tricks.
* The Perfect Setup:: The right tools.
* Coding Style:: Hygiene of the contributor.
* Submitting Patches:: Share your work.
Coding Style
* Programming Paradigm:: How to compose your elements.
* Modules:: Where to store your code?
* Data Types and Pattern Matching:: Implementing data structures.
* Formatting Code:: Writing conventions.
@end menu
@c *********************************************************************
@node Introduction
@chapter Introduction
GNU Guix@footnote{``Guix'' is pronounced like ``geeks'', or ``ɡiːks''
using the international phonetic alphabet (IPA).} is a package
management tool for the GNU system. Guix makes it easy for unprivileged
users to install, upgrade, or remove packages, to roll back to a
previous package set, to build packages from source, and generally
assists with the creation and maintenance of software environments.
@cindex user interfaces
Guix provides a command-line package management interface
(@pxref{Invoking guix package}), a set of command-line utilities
(@pxref{Utilities}), as well as Scheme programming interfaces
(@pxref{Programming Interface}).
@cindex build daemon
Its @dfn{build daemon} is responsible for building packages on behalf of
users (@pxref{Setting Up the Daemon}) and for downloading pre-built
binaries from authorized sources (@pxref{Substitutes}).
@cindex extensibility of the distribution
Guix includes package definitions for many GNU and non-GNU packages, all
of which @uref{https://www.gnu.org/philosophy/free-sw.html, respect the
user's computing freedom}. It is @emph{extensible}: users can write
their own package definitions (@pxref{Defining Packages}) and make them
available as independent package modules (@pxref{Package Modules}). It
is also @emph{customizable}: users can @emph{derive} specialized package
definitions from existing ones, including from the command line
(@pxref{Package Transformation Options}).
@cindex Guix System Distribution
@cindex GuixSD
You can install GNU@tie{}Guix on top of an existing GNU/Linux system
where it complements the available tools without interference
(@pxref{Installation}), or you can use it as part of the standalone
@dfn{Guix System Distribution} or GuixSD (@pxref{GNU Distribution}).
With GNU@tie{}GuixSD, you @emph{declare} all aspects of the operating
system configuration and Guix takes care of instantiating the
configuration in a transactional, reproducible, and stateless fashion
(@pxref{System Configuration}).
@cindex functional package management
Under the hood, Guix implements the @dfn{functional package management}
discipline pioneered by Nix (@pxref{Acknowledgments}).
In Guix, the package build and installation process is seen
as a @emph{function}, in the mathematical sense. That function takes inputs,
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such as build scripts, a compiler, and libraries, and
returns an installed package. As a pure function, its result depends
solely on its inputs---for instance, it cannot refer to software or
scripts that were not explicitly passed as inputs. A build function
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always produces the same result when passed a given set of inputs. It
cannot alter the environment of the running system in
any way; for instance, it cannot create, modify, or delete files outside
of its build and installation directories. This is achieved by running
build processes in isolated environments (or @dfn{containers}), where only their
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explicit inputs are visible.
The result of package build functions is @dfn{cached} in the file
system, in a special directory called @dfn{the store} (@pxref{The
Store}). Each package is installed in a directory of its own in the
store---by default under @file{/gnu/store}. The directory name contains
a hash of all the inputs used to build that package; thus, changing an
input yields a different directory name.
This approach is the foundation for the salient features of Guix: support
for transactional package upgrade and rollback, per-user installation, and
garbage collection of packages (@pxref{Features}).
@c *********************************************************************
@node Installation
@chapter Installation
GNU Guix is available for download from its website at
@url{http://www.gnu.org/software/guix/}. This section describes the
software requirements of Guix, as well as how to install it and get
ready to use it.
Note that this section is concerned with the installation of the package
manager, which can be done on top of a running GNU/Linux system. If,
instead, you want to install the complete GNU operating system,
@pxref{System Installation}.
@cindex foreign distro
When installed on a running GNU/Linux system---thereafter called a
@dfn{foreign distro}---GNU@tie{}Guix complements the available tools
without interference. Its data lives exclusively in two directories,
usually @file{/gnu/store} and @file{/var/guix}; other files on your
system, such as @file{/etc}, are left untouched.
Once installed, Guix can be updated by running @command{guix pull}
(@pxref{Invoking guix pull}).
* Binary Installation:: Getting Guix running in no time!
* Requirements:: Software needed to build and run Guix.
* Running the Test Suite:: Testing Guix.
* Setting Up the Daemon:: Preparing the build daemon's environment.
* Invoking guix-daemon:: Running the build daemon.
* Application Setup:: Application-specific setup.
@node Binary Installation
@section Binary Installation
This section describes how to install Guix on an arbitrary system from a
self-contained tarball providing binaries for Guix and for all its
dependencies. This is often quicker than installing from source, which
is described in the next sections. The only requirement is to have
GNU@tie{}tar and Xz.
Installing goes along these lines:
@enumerate
@item
Download the binary tarball from
@indicateurl{ftp://alpha.gnu.org/gnu/guix/guix-binary-@value{VERSION}.@var{system}.tar.xz},
where @var{system} is @code{x86_64-linux} for an @code{x86_64} machine
already running the kernel Linux, and so on.
@c The following is somewhat duplicated in ``System Installation''.
Make sure to download the associated @file{.sig} file and to verify the
authenticity of the tarball against it, along these lines:
@example
$ wget ftp://alpha.gnu.org/gnu/guix/guix-binary-@value{VERSION}.@var{system}.tar.xz.sig
$ gpg --verify guix-binary-@value{VERSION}.@var{system}.tar.xz.sig
@end example
If that command fails because you do not have the required public key,
then run this command to import it:
@example
$ gpg --keyserver pgp.mit.edu --recv-keys @value{OPENPGP-SIGNING-KEY-ID}
@end example
@noindent
and rerun the @code{gpg --verify} command.
@c end authentication part
@item
As @code{root}, run:
@example
# tar --warning=no-timestamp -xf \
guix-binary-@value{VERSION}.@var{system}.tar.xz
# mv var/guix /var/ && mv gnu /
@end example
This creates @file{/gnu/store} (@pxref{The Store}) and @file{/var/guix}.
The latter contains a ready-to-use profile for @code{root} (see next
step.)
Do @emph{not} unpack the tarball on a working Guix system since that
would overwrite its own essential files.
The @code{--warning=no-timestamp} option makes sure GNU@tie{}tar does
not emit warnings about ``implausibly old time stamps'' (such
warnings were triggered by GNU@tie{}tar 1.26 and older; recent
versions are fine.)
They stem from the fact that all the
files in the archive have their modification time set to zero (which
means January 1st, 1970.) This is done on purpose to make sure the
archive content is independent of its creation time, thus making it
reproducible.
@item
Make @code{root}'s profile available under @file{~/.guix-profile}:
@example
# ln -sf /var/guix/profiles/per-user/root/guix-profile \
~root/.guix-profile
@end example
Source @file{etc/profile} to augment @code{PATH} and other relevant
environment variables:
@example
# GUIX_PROFILE=$HOME/.guix-profile \
source $GUIX_PROFILE/etc/profile
@end example
@item
Create the group and user accounts for build users as explained below
(@pxref{Build Environment Setup}).
Run the daemon, and set it to automatically start on boot.
If your host distro uses the systemd init system, this can be achieved
with these commands:
@c Versions of systemd that supported symlinked service files are not
@c yet widely deployed, so we should suggest that users copy the service
@c files into place.
@c
@c See this thread for more information:
@c http://lists.gnu.org/archive/html/guix-devel/2017-01/msg01199.html
# cp ~root/.guix-profile/lib/systemd/system/guix-daemon.service \
/etc/systemd/system/
# systemctl start guix-daemon && systemctl enable guix-daemon
@end example
If your host distro uses the Upstart init system:
# initctl reload-configuration
# cp ~root/.guix-profile/lib/upstart/system/guix-daemon.conf /etc/init/
# start guix-daemon
@end example
Otherwise, you can still start the daemon manually with:
@example
# ~root/.guix-profile/bin/guix-daemon --build-users-group=guixbuild
@end example
@item
Make the @command{guix} command available to other users on the machine,
for instance with:
@example
# mkdir -p /usr/local/bin
# cd /usr/local/bin
# ln -s /var/guix/profiles/per-user/root/guix-profile/bin/guix
It is also a good idea to make the Info version of this manual available
there:
@example
# mkdir -p /usr/local/share/info
# cd /usr/local/share/info
# for i in /var/guix/profiles/per-user/root/guix-profile/share/info/* ;
do ln -s $i ; done
@end example
That way, assuming @file{/usr/local/share/info} is in the search path,
running @command{info guix} will open this manual (@pxref{Other Info
Directories,,, texinfo, GNU Texinfo}, for more details on changing the
Info search path.)
@cindex substitutes, authorization thereof
To use substitutes from @code{hydra.gnu.org} or one of its mirrors
(@pxref{Substitutes}), authorize them:
# guix archive --authorize < ~root/.guix-profile/share/guix/hydra.gnu.org.pub
@item
Each user may need to perform a few additional steps to make their Guix
environment ready for use, @pxref{Application Setup}.
@end enumerate
Voilà, the installation is complete!
You can confirm that Guix is working by installing a sample package into
the root profile:
@end example
The @code{guix} package must remain available in @code{root}'s profile,
or it would become subject to garbage collection---in which case you
would find yourself badly handicapped by the lack of the @command{guix}
command. In other words, do not remove @code{guix} by running
@code{guix package -r guix}.
The binary installation tarball can be (re)produced and verified simply
by running the following command in the Guix source tree:
@example
make guix-binary.@var{system}.tar.xz
@end example
@noindent
... which, in turn, runs:
@example
guix pack -s @var{system} --localstatedir guix
@end example
@xref{Invoking guix pack}, for more info on this handy tool.
@node Requirements
@section Requirements
This section lists requirements when building Guix from source. The
build procedure for Guix is the same as for other GNU software, and is
not covered here. Please see the files @file{README} and @file{INSTALL}
in the Guix source tree for additional details.
GNU Guix depends on the following packages:
@itemize
@item @url{http://gnu.org/software/guile/, GNU Guile}, version 2.0.9 or
@item @url{http://gnupg.org/, GNU libgcrypt};
@item
@uref{http://gnutls.org/, GnuTLS}, specifically its Guile bindings
(@pxref{Guile Preparations, how to install the GnuTLS bindings for
Guile,, gnutls-guile, GnuTLS-Guile});
@item
@c FIXME: Specify a version number once a release has been made.
@uref{https://gitlab.com/guile-git/guile-git, Guile-Git}, from August
2017 or later;
@item @url{http://www.gnu.org/software/make/, GNU Make}.
@end itemize
The following dependencies are optional:
@itemize
@url{http://savannah.nongnu.org/projects/guile-json/, Guile-JSON} will
allow you to use the @command{guix import pypi} command (@pxref{Invoking
guix import}). It is of
interest primarily for developers and not for casual users.
@item
@c Note: We need at least 0.10.2 for 'channel-send-eof'.
Support for build offloading (@pxref{Daemon Offload Setup}) and
@command{guix copy} (@pxref{Invoking guix copy}) depends on
@uref{https://github.com/artyom-poptsov/guile-ssh, Guile-SSH},
version 0.10.2 or later.
@item
When @url{http://zlib.net, zlib} is available, @command{guix publish}
can compress build byproducts (@pxref{Invoking guix publish}).
@end itemize
Unless @code{--disable-daemon} was passed to @command{configure}, the
following packages are also needed:
@itemize
@item @url{http://sqlite.org, SQLite 3};
@item @url{http://www.bzip.org, libbz2};
@item @url{http://gcc.gnu.org, GCC's g++}, with support for the
C++11 standard.
When configuring Guix on a system that already has a Guix installation,
be sure to specify the same state directory as the existing installation
using the @code{--localstatedir} option of the @command{configure}
script (@pxref{Directory Variables, @code{localstatedir},, standards,
GNU Coding Standards}). The @command{configure} script protects against
unintended misconfiguration of @var{localstatedir} so you do not
inadvertently corrupt your store (@pxref{The Store}).
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When a working installation of @url{http://nixos.org/nix/, the Nix package
manager} is available, you
can instead configure Guix with @code{--disable-daemon}. In that case,
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Nix replaces the three dependencies above.
Guix is compatible with Nix, so it is possible to share the same store
between both. To do so, you must pass @command{configure} not only the
same @code{--with-store-dir} value, but also the same
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@code{--localstatedir} value. The latter is essential because it
specifies where the database that stores metadata about the store is
located, among other things. The default values for Nix are
@code{--with-store-dir=/nix/store} and @code{--localstatedir=/nix/var}.
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Note that @code{--disable-daemon} is not required if
your goal is to share the store with Nix.
@node Running the Test Suite
@section Running the Test Suite
After a successful @command{configure} and @code{make} run, it is a good
idea to run the test suite. It can help catch issues with the setup or
environment, or bugs in Guix itself---and really, reporting test
failures is a good way to help improve the software. To run the test
suite, type:
@example
make check
@end example
Test cases can run in parallel: you can use the @code{-j} option of
GNU@tie{}make to speed things up. The first run may take a few minutes
on a recent machine; subsequent runs will be faster because the store
that is created for test purposes will already have various things in
cache.
It is also possible to run a subset of the tests by defining the
@code{TESTS} makefile variable as in this example:
@example
make check TESTS="tests/store.scm tests/cpio.scm"
@end example
By default, tests results are displayed at a file level. In order to
see the details of every individual test cases, it is possible to define
the @code{SCM_LOG_DRIVER_FLAGS} makefile variable as in this example:
@example
make check TESTS="tests/base64.scm" SCM_LOG_DRIVER_FLAGS="--brief=no"
@end example
Upon failure, please email @email{bug-guix@@gnu.org} and attach the
@file{test-suite.log} file. Please specify the Guix version being used
as well as version numbers of the dependencies (@pxref{Requirements}) in
your message.
Guix also comes with a whole-system test suite that tests complete
GuixSD operating system instances. It can only run on systems where
Guix is already installed, using:
@example
make check-system
@end example
@noindent
or, again, by defining @code{TESTS} to select a subset of tests to run:
@example
make check-system TESTS="basic mcron"
@end example
These system tests are defined in the @code{(gnu tests @dots{})}
modules. They work by running the operating systems under test with
lightweight instrumentation in a virtual machine (VM). They can be
computationally intensive or rather cheap, depending on whether
substitutes are available for their dependencies (@pxref{Substitutes}).
Some of them require a lot of storage space to hold VM images.
Again in case of test failures, please send @email{bug-guix@@gnu.org}
all the details.
@node Setting Up the Daemon
@section Setting Up the Daemon
@cindex daemon
Operations such as building a package or running the garbage collector
are all performed by a specialized process, the @dfn{build daemon}, on
behalf of clients. Only the daemon may access the store and its
associated database. Thus, any operation that manipulates the store
goes through the daemon. For instance, command-line tools such as
@command{guix package} and @command{guix build} communicate with the
daemon (@i{via} remote procedure calls) to instruct it what to do.
The following sections explain how to prepare the build daemon's
environment. See also @ref{Substitutes}, for information on how to allow
the daemon to download pre-built binaries.
@menu
* Build Environment Setup:: Preparing the isolated build environment.
* Daemon Offload Setup:: Offloading builds to remote machines.
@end menu
@node Build Environment Setup
@subsection Build Environment Setup
In a standard multi-user setup, Guix and its daemon---the
@command{guix-daemon} program---are installed by the system
administrator; @file{/gnu/store} is owned by @code{root} and
@command{guix-daemon} runs as @code{root}. Unprivileged users may use
Guix tools to build packages or otherwise access the store, and the
daemon will do it on their behalf, ensuring that the store is kept in a
consistent state, and allowing built packages to be shared among users.
@cindex build users
When @command{guix-daemon} runs as @code{root}, you may not want package
build processes themselves to run as @code{root} too, for obvious
security reasons. To avoid that, a special pool of @dfn{build users}
should be created for use by build processes started by the daemon.
These build users need not have a shell and a home directory: they will
just be used when the daemon drops @code{root} privileges in build
processes. Having several such users allows the daemon to launch
distinct build processes under separate UIDs, which guarantees that they
do not interfere with each other---an essential feature since builds are
regarded as pure functions (@pxref{Introduction}).
On a GNU/Linux system, a build user pool may be created like this (using
Bash syntax and the @code{shadow} commands):
@c See http://lists.gnu.org/archive/html/bug-guix/2013-01/msg00239.html
@c for why `-G' is needed.
# groupadd --system guixbuild
# for i in `seq -w 1 10`;
useradd -g guixbuild -G guixbuild \
-d /var/empty -s `which nologin` \
-c "Guix build user $i" --system \
guixbuilder$i;
done
@end example
@noindent
The number of build users determines how many build jobs may run in
parallel, as specified by the @option{--max-jobs} option
(@pxref{Invoking guix-daemon, @option{--max-jobs}}). To use
@command{guix system vm} and related commands, you may need to add the
build users to the @code{kvm} group so they can access @file{/dev/kvm},
using @code{-G guixbuild,kvm} instead of @code{-G guixbuild}
(@pxref{Invoking guix system}).
The @code{guix-daemon} program may then be run as @code{root} with the
following command@footnote{If your machine uses the systemd init system,
dropping the @file{@var{prefix}/lib/systemd/system/guix-daemon.service}
file in @file{/etc/systemd/system} will ensure that
@command{guix-daemon} is automatically started. Similarly, if your
machine uses the Upstart init system, drop the
@file{@var{prefix}/lib/upstart/system/guix-daemon.conf}
file in @file{/etc/init}.}:
# guix-daemon --build-users-group=guixbuild
@cindex chroot
@noindent
This way, the daemon starts build processes in a chroot, under one of
the @code{guixbuilder} users. On GNU/Linux, by default, the chroot
environment contains nothing but:
@c Keep this list in sync with libstore/build.cc! -----------------------
@itemize
@item
a minimal @code{/dev} directory, created mostly independently from the
host @code{/dev}@footnote{``Mostly'', because while the set of files
that appear in the chroot's @code{/dev} is fixed, most of these files
can only be created if the host has them.};
@item
the @code{/proc} directory; it only shows the processes of the container
since a separate PID name space is used;
@item
@file{/etc/passwd} with an entry for the current user and an entry for
user @file{nobody};
@item
@file{/etc/group} with an entry for the user's group;
@item
@file{/etc/hosts} with an entry that maps @code{localhost} to
@code{127.0.0.1};
@item
a writable @file{/tmp} directory.
@end itemize
You can influence the directory where the daemon stores build trees
@i{via} the @code{TMPDIR} environment variable. However, the build tree
within the chroot is always called @file{/tmp/guix-build-@var{name}.drv-0},
where @var{name} is the derivation name---e.g., @code{coreutils-8.24}.
This way, the value of @code{TMPDIR} does not leak inside build
environments, which avoids discrepancies in cases where build processes
capture the name of their build tree.
@vindex http_proxy
The daemon also honors the @code{http_proxy} environment variable for
HTTP downloads it performs, be it for fixed-output derivations
(@pxref{Derivations}) or for substitutes (@pxref{Substitutes}).
If you are installing Guix as an unprivileged user, it is still possible
to run @command{guix-daemon} provided you pass @code{--disable-chroot}.
However, build processes will not be isolated from one another, and not
from the rest of the system. Thus, build processes may interfere with
each other, and may access programs, libraries, and other files
available on the system---making it much harder to view them as
@emph{pure} functions.
@node Daemon Offload Setup
@subsection Using the Offload Facility
@cindex offloading
When desired, the build daemon can @dfn{offload} derivation builds to
other machines running Guix, using the @code{offload} @dfn{build
hook}@footnote{This feature is available only when
@uref{https://github.com/artyom-poptsov/guile-ssh, Guile-SSH} is
present.}. When that
feature is enabled, a list of user-specified build machines is read from
@file{/etc/guix/machines.scm}; every time a build is requested, for
instance via @code{guix build}, the daemon attempts to offload it to one
of the machines that satisfy the constraints of the derivation, in
particular its system type---e.g., @file{x86_64-linux}. Missing
prerequisites for the build are copied over SSH to the target machine,
which then proceeds with the build; upon success the output(s) of the
build are copied back to the initial machine.
The @file{/etc/guix/machines.scm} file typically looks like this:
@example
(list (build-machine
(name "eightysix.example.org")
(system "x86_64-linux")
(host-key "ssh-ed25519 AAAAC3Nza@dots{}")
(speed 2.)) ;incredibly fast!
(build-machine
(name "meeps.example.org")
(system "mips64el-linux")
(host-key "ssh-rsa AAAAB3Nza@dots{}")
(user "alice")
(private-key
(string-append (getenv "HOME")
"/.ssh/identity-for-guix"))))
@end example
@noindent
In the example above we specify a list of two build machines, one for
the @code{x86_64} architecture and one for the @code{mips64el}
architecture.
In fact, this file is---not surprisingly!---a Scheme file that is
evaluated when the @code{offload} hook is started. Its return value
must be a list of @code{build-machine} objects. While this example
shows a fixed list of build machines, one could imagine, say, using
DNS-SD to return a list of potential build machines discovered in the
local network (@pxref{Introduction, Guile-Avahi,, guile-avahi, Using
Avahi in Guile Scheme Programs}). The @code{build-machine} data type is
detailed below.
This data type represents build machines to which the daemon may offload
builds. The important fields are:
@table @code
@item name
The system type of the remote machine---e.g., @code{"x86_64-linux"}.
@item user
The user account to use when connecting to the remote machine over SSH.
Note that the SSH key pair must @emph{not} be passphrase-protected, to
allow non-interactive logins.
@item host-key
This must be the machine's SSH @dfn{public host key} in OpenSSH format.
This is used to authenticate the machine when we connect to it. It is a
long string that looks like this:
@example
ssh-ed25519 AAAAC3NzaC@dots{}mde+UhL hint@@example.org
@end example
If the machine is running the OpenSSH daemon, @command{sshd}, the host
key can be found in a file such as
@file{/etc/ssh/ssh_host_ed25519_key.pub}.
If the machine is running the SSH daemon of GNU@tie{}lsh,
@command{lshd}, the host key is in @file{/etc/lsh/host-key.pub} or a
similar file. It can be converted to the OpenSSH format using
@command{lsh-export-key} (@pxref{Converting keys,,, lsh, LSH Manual}):
@example
$ lsh-export-key --openssh < /etc/lsh/host-key.pub
ssh-rsa AAAAB3NzaC1yc2EAAAAEOp8FoQAAAQEAs1eB46LV@dots{}
@end example
A number of optional fields may be specified:
@item @code{port} (default: @code{22})
Port number of SSH server on the machine.
@item @code{private-key} (default: @file{~root/.ssh/id_rsa})
The SSH private key file to use when connecting to the machine, in
OpenSSH format.
Note that the default value is the private key @emph{of the root
account}. Make sure it exists if you use the default.
@item @code{compression} (default: @code{"zlib@@openssh.com,zlib"})
@itemx @code{compression-level} (default: @code{3})
The SSH-level compression methods and compression level requested.
Note that offloading relies on SSH compression to reduce bandwidth usage
when transferring files to and from build machines.
@item @code{daemon-socket} (default: @code{"/var/guix/daemon-socket/socket"})
File name of the Unix-domain socket @command{guix-daemon} is listening
to on that machine.
@item @code{parallel-builds} (default: @code{1})
The number of builds that may run in parallel on the machine.
@item @code{speed} (default: @code{1.0})
A ``relative speed factor''. The offload scheduler will tend to prefer
machines with a higher speed factor.
@item @code{features} (default: @code{'()})
A list of strings denoting specific features supported by the machine.
An example is @code{"kvm"} for machines that have the KVM Linux modules
and corresponding hardware support. Derivations can request features by
name, and they will be scheduled on matching build machines.
@end table
The @code{guile} command must be in the search path on the build
machines. In addition, the Guix modules must be in
@code{$GUILE_LOAD_PATH} on the build machine---you can check whether
this is the case by running:
@example
ssh build-machine guile -c "'(use-modules (guix config))'"
There is one last thing to do once @file{machines.scm} is in place. As
explained above, when offloading, files are transferred back and forth
between the machine stores. For this to work, you first need to
generate a key pair on each machine to allow the daemon to export signed
archives of files from the store (@pxref{Invoking guix archive}):
@example
# guix archive --generate-key
@end example
@noindent
Each build machine must authorize the key of the master machine so that
it accepts store items it receives from the master:
@example
# guix archive --authorize < master-public-key.txt
@end example
@noindent
Likewise, the master machine must authorize the key of each build machine.
All the fuss with keys is here to express pairwise mutual trust
relations between the master and the build machines. Concretely, when
the master receives files from a build machine (and @i{vice versa}), its
build daemon can make sure they are genuine, have not been tampered
with, and that they are signed by an authorized key.
@cindex offload test
To test whether your setup is operational, run this command on the
master node:
@example
# guix offload test
@end example
This will attempt to connect to each of the build machines specified in
@file{/etc/guix/machines.scm}, make sure Guile and the Guix modules are
available on each machine, attempt to export to the machine and import
from it, and report any error in the process.
If you want to test a different machine file, just specify it on the
command line:
@example
# guix offload test machines-qualif.scm
@end example
Last, you can test the subset of the machines whose name matches a
regular expression like this:
@example
# guix offload test machines.scm '\.gnu\.org$'
@end example
@node Invoking guix-daemon
@section Invoking @command{guix-daemon}
The @command{guix-daemon} program implements all the functionality to
access the store. This includes launching build processes, running the
garbage collector, querying the availability of a build result, etc. It
is normally run as @code{root} like this:
@example
# guix-daemon --build-users-group=guixbuild
@end example
@noindent
For details on how to set it up, @pxref{Setting Up the Daemon}.
@cindex chroot
@cindex container, build environment
@cindex build environment
@cindex reproducible builds
By default, @command{guix-daemon} launches build processes under
different UIDs, taken from the build group specified with
@code{--build-users-group}. In addition, each build process is run in a
chroot environment that only contains the subset of the store that the
build process depends on, as specified by its derivation
(@pxref{Programming Interface, derivation}), plus a set of specific
system directories. By default, the latter contains @file{/dev} and
@file{/dev/pts}. Furthermore, on GNU/Linux, the build environment is a
@dfn{container}: in addition to having its own file system tree, it has
a separate mount name space, its own PID name space, network name space,
etc. This helps achieve reproducible builds (@pxref{Features}).
When the daemon performs a build on behalf of the user, it creates a
build directory under @file{/tmp} or under the directory specified by
its @code{TMPDIR} environment variable; this directory is shared with
the container for the duration of the build. Be aware that using a
directory other than @file{/tmp} can affect build results---for example,
with a longer directory name, a build process that uses Unix-domain
sockets might hit the name length limitation for @code{sun_path}, which
it would otherwise not hit.
The build directory is automatically deleted upon completion, unless the
build failed and the client specified @option{--keep-failed}
(@pxref{Invoking guix build, @option{--keep-failed}}).
The following command-line options are supported:
@table @code
@item --build-users-group=@var{group}
Take users from @var{group} to run build processes (@pxref{Setting Up
the Daemon, build users}).
@cindex substitutes
Do not use substitutes for build products. That is, always build things
locally instead of allowing downloads of pre-built binaries
(@pxref{Substitutes}).
By default substitutes are used, unless the client---such as the
@command{guix package} command---is explicitly invoked with
@code{--no-substitutes}.
When the daemon runs with @code{--no-substitutes}, clients can still
explicitly enable substitution @i{via} the @code{set-build-options}
remote procedure call (@pxref{The Store}).
@item --substitute-urls=@var{urls}
@anchor{daemon-substitute-urls}
Consider @var{urls} the default whitespace-separated list of substitute
source URLs. When this option is omitted,
@indicateurl{https://mirror.hydra.gnu.org https://hydra.gnu.org} is used
(@code{mirror.hydra.gnu.org} is a mirror of @code{hydra.gnu.org}).
This means that substitutes may be downloaded from @var{urls}, as long
as they are signed by a trusted signature (@pxref{Substitutes}).
@cindex build hook
@item --no-build-hook
Do not use the @dfn{build hook}.
The build hook is a helper program that the daemon can start and to
which it submits build requests. This mechanism is used to offload
builds to other machines (@pxref{Daemon Offload Setup}).
@item --cache-failures
Cache build failures. By default, only successful builds are cached.
When this option is used, @command{guix gc --list-failures} can be used
to query the set of store items marked as failed; @command{guix gc
--clear-failures} removes store items from the set of cached failures.
@xref{Invoking guix gc}.
@item --cores=@var{n}
@itemx -c @var{n}
Use @var{n} CPU cores to build each derivation; @code{0} means as many
as available.
The default value is @code{0}, but it may be overridden by clients, such
as the @code{--cores} option of @command{guix build} (@pxref{Invoking
guix build}).
The effect is to define the @code{NIX_BUILD_CORES} environment variable
in the build process, which can then use it to exploit internal
parallelism---for instance, by running @code{make -j$NIX_BUILD_CORES}.
@item --max-jobs=@var{n}
@itemx -M @var{n}
Allow at most @var{n} build jobs in parallel. The default value is
@code{1}. Setting it to @code{0} means that no builds will be performed
locally; instead, the daemon will offload builds (@pxref{Daemon Offload
Setup}), or simply fail.
@item --max-silent-time=@var{seconds}
When the build or substitution process remains silent for more than
@var{seconds}, terminate it and report a build failure.
The default value is @code{0}, which disables the timeout.
The value specified here can be overridden by clients (@pxref{Common
Build Options, @code{--max-silent-time}}).
@item --timeout=@var{seconds}
Likewise, when the build or substitution process lasts for more than
@var{seconds}, terminate it and report a build failure.
The default value is @code{0}, which disables the timeout.
The value specified here can be overridden by clients (@pxref{Common
Build Options, @code{--timeout}}).
@item --rounds=@var{N}
Build each derivation @var{n} times in a row, and raise an error if
consecutive build results are not bit-for-bit identical. Note that this
setting can be overridden by clients such as @command{guix build}
(@pxref{Invoking guix build}).
When used in conjunction with @option{--keep-failed}, the differing
output is kept in the store, under @file{/gnu/store/@dots{}-check}.
This makes it easy to look for differences between the two results.
@item --debug
Produce debugging output.
This is useful to debug daemon start-up issues, but then it may be
overridden by clients, for example the @code{--verbosity} option of
@command{guix build} (@pxref{Invoking guix build}).
@item --chroot-directory=@var{dir}
Add @var{dir} to the build chroot.
Doing this may change the result of build processes---for instance if
they use optional dependencies found in @var{dir} when it is available,
and not otherwise. For that reason, it is not recommended to do so.
Instead, make sure that each derivation declares all the inputs that it
needs.
@item --disable-chroot
Disable chroot builds.
Using this option is not recommended since, again, it would allow build
processes to gain access to undeclared dependencies. It is necessary,
though, when @command{guix-daemon} is running under an unprivileged user
account.
@item --disable-log-compression
Disable compression of the build logs.
Unless @code{--lose-logs} is used, all the build logs are kept in the
@var{localstatedir}. To save space, the daemon automatically compresses
them with bzip2 by default. This option disables that.
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@item --disable-deduplication
@cindex deduplication
Disable automatic file ``deduplication'' in the store.
By default, files added to the store are automatically ``deduplicated'':
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if a newly added file is identical to another one found in the store,
the daemon makes the new file a hard link to the other file. This can
noticeably reduce disk usage, at the expense of slightly increased
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input/output load at the end of a build process. This option disables
this optimization.
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@item --gc-keep-outputs[=yes|no]
Tell whether the garbage collector (GC) must keep outputs of live
derivations.
When set to ``yes'', the GC will keep the outputs of any live derivation
available in the store---the @code{.drv} files. The default is ``no'',
meaning that derivation outputs are kept only if they are GC roots.
@item --gc-keep-derivations[=yes|no]
Tell whether the garbage collector (GC) must keep derivations
corresponding to live outputs.
When set to ``yes'', as is the case by default, the GC keeps
derivations---i.e., @code{.drv} files---as long as at least one of their
outputs is live. This allows users to keep track of the origins of
items in their store. Setting it to ``no'' saves a bit of disk space.
Note that when both @code{--gc-keep-derivations} and
@code{--gc-keep-outputs} are used, the effect is to keep all the build
prerequisites (the sources, compiler, libraries, and other build-time
tools) of live objects in the store, regardless of whether these
prerequisites are live. This is convenient for developers since it
saves rebuilds or downloads.
@item --impersonate-linux-2.6
On Linux-based systems, impersonate Linux 2.6. This means that the
kernel's @code{uname} system call will report 2.6 as the release number.
This might be helpful to build programs that (usually wrongfully) depend
on the kernel version number.
@item --lose-logs
Do not keep build logs. By default they are kept under
@code{@var{localstatedir}/guix/log}.
@item --system=@var{system}
Assume @var{system} as the current system type. By default it is the
architecture/kernel pair found at configure time, such as
@code{x86_64-linux}.
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@item --listen=@var{endpoint}
Listen for connections on @var{endpoint}. @var{endpoint} is interpreted
as the file name of a Unix-domain socket if it starts with
@code{/} (slash sign). Otherwise, @var{endpoint} is interpreted as a
host name or host name and port to listen to. Here are a few examples:
@table @code
@item --listen=/gnu/var/daemon
Listen for connections on the @file{/gnu/var/daemon} Unix-domain socket,
creating it if needed.
@item --listen=localhost
@cindex daemon, remote access
@cindex remote access to the daemon
@cindex daemon, cluster setup
@cindex clusters, daemon setup
Listen for TCP connections on the network interface corresponding to
@code{localhost}, on port 44146.
@item --listen=128.0.0.42:1234
Listen for TCP connections on the network interface corresponding to
@code{128.0.0.42}, on port 1234.
@end table
This option can be repeated multiple times, in which case
@command{guix-daemon} accepts connections on all the specified
endpoints. Users can tell client commands what endpoint to connect to
by setting the @code{GUIX_DAEMON_SOCKET} environment variable
(@pxref{The Store, @code{GUIX_DAEMON_SOCKET}}).
@quotation Note
The daemon protocol is @emph{unauthenticated and unencrypted}. Using
@code{--listen=@var{host}} is suitable on local networks, such as
clusters, where only trusted nodes may connect to the build daemon. In
other cases where remote access to the daemon is needed, we recommend
using Unix-domain sockets along with SSH.
@end quotation
When @code{--listen} is omitted, @command{guix-daemon} listens for
connections on the Unix-domain socket located at
@file{@var{localstatedir}/daemon-socket/socket}.
@node Application Setup
@section Application Setup
@cindex foreign distro
When using Guix on top of GNU/Linux distribution other than GuixSD---a
so-called @dfn{foreign distro}---a few additional steps are needed to
get everything in place. Here are some of them.
@anchor{locales-and-locpath}
@cindex locales, when not on GuixSD
@vindex GUIX_LOCPATH
Packages installed @i{via} Guix will not use the locale data of the
host system. Instead, you must first install one of the locale packages
available with Guix and then define the @code{GUIX_LOCPATH} environment
variable:
@example
$ guix package -i glibc-locales
$ export GUIX_LOCPATH=$HOME/.guix-profile/lib/locale
@end example
Note that the @code{glibc-locales} package contains data for all the
locales supported by the GNU@tie{}libc and weighs in at around
110@tie{}MiB. Alternatively, the @code{glibc-utf8-locales} is smaller but
limited to a few UTF-8 locales.
The @code{GUIX_LOCPATH} variable plays a role similar to @code{LOCPATH}
(@pxref{Locale Names, @code{LOCPATH},, libc, The GNU C Library Reference
Manual}). There are two important differences though:
@enumerate
@item
@code{GUIX_LOCPATH} is honored only by the libc in Guix, and not by the libc
provided by foreign distros. Thus, using @code{GUIX_LOCPATH} allows you
to make sure the programs of the foreign distro will not end up loading
incompatible locale data.
@item
libc suffixes each entry of @code{GUIX_LOCPATH} with @code{/X.Y}, where
@code{X.Y} is the libc version---e.g., @code{2.22}. This means that,
should your Guix profile contain a mixture of programs linked against
different libc version, each libc version will only try to load locale
data in the right format.
@end enumerate
This is important because the locale data format used by different libc
versions may be incompatible.
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@subsection Name Service Switch
@cindex name service switch, glibc
@cindex NSS (name service switch), glibc
@cindex nscd (name service caching daemon)
@cindex name service caching daemon (nscd)
When using Guix on a foreign distro, we @emph{strongly recommend} that
the system run the GNU C library's @dfn{name service cache daemon},
@command{nscd}, which should be listening on the
@file{/var/run/nscd/socket} socket. Failing to do that, applications
installed with Guix may fail to look up host names or user accounts, or
may even crash. The next paragraphs explain why.
@cindex @file{nsswitch.conf}
The GNU C library implements a @dfn{name service switch} (NSS), which is
an extensible mechanism for ``name lookups'' in general: host name
resolution, user accounts, and more (@pxref{Name Service Switch,,, libc,
The GNU C Library Reference Manual}).
@cindex Network information service (NIS)
@cindex NIS (Network information service)
Being extensible, the NSS supports @dfn{plugins}, which provide new name
lookup implementations: for example, the @code{nss-mdns} plugin allow
resolution of @code{.local} host names, the @code{nis} plugin allows
user account lookup using the Network information service (NIS), and so
on. These extra ``lookup services'' are configured system-wide in
@file{/etc/nsswitch.conf}, and all the programs running on the system
honor those settings (@pxref{NSS Configuration File,,, libc, The GNU C
Reference Manual}).
When they perform a name lookup---for instance by calling the
@code{getaddrinfo} function in C---applications first try to connect to
the nscd; on success, nscd performs name lookups on their behalf. If
the nscd is not running, then they perform the name lookup by
themselves, by loading the name lookup services into their own address
space and running it. These name lookup services---the
@file{libnss_*.so} files---are @code{dlopen}'d, but they may come from
the host system's C library, rather than from the C library the
application is linked against (the C library coming from Guix).
And this is where the problem is: if your application is linked against
Guix's C library (say, glibc 2.24) and tries to load NSS plugins from
another C library (say, @code{libnss_mdns.so} for glibc 2.22), it will
likely crash or have its name lookups fail unexpectedly.
Running @command{nscd} on the system, among other advantages, eliminates
this binary incompatibility problem because those @code{libnss_*.so}
files are loaded in the @command{nscd} process, not in applications
themselves.
The majority of graphical applications use Fontconfig to locate and
load fonts and perform X11-client-side rendering. The @code{fontconfig}
package in Guix looks for fonts in @file{$HOME/.guix-profile}
by default. Thus, to allow graphical applications installed with Guix
to display fonts, you have to install fonts with Guix as well.
Essential font packages include @code{gs-fonts}, @code{font-dejavu}, and
To display text written in Chinese languages, Japanese, or Korean in
graphical applications, consider installing
@code{font-adobe-source-han-sans} or @code{font-wqy-zenhei}. The former
has multiple outputs, one per language family (@pxref{Packages with
Multiple Outputs}). For instance, the following command installs fonts
for Chinese languages:
@example
guix package -i font-adobe-source-han-sans:cn
@end example
Older programs such as @command{xterm} do not use Fontconfig and instead
rely on server-side font rendering. Such programs require to specify a
full name of a font using XLFD (X Logical Font Description), like this:
@example
-*-dejavu sans-medium-r-normal-*-*-100-*-*-*-*-*-1
@end example
To be able to use such full names for the TrueType fonts installed in
your Guix profile, you need to extend the font path of the X server:
@example
xset +fp ~/.guix-profile/share/fonts/truetype
@end example
After that, you can run @code{xlsfonts} (from @code{xlsfonts} package)
to make sure your TrueType fonts are listed there.
@cindex @code{fc-cache}
@cindex font cache
After installing fonts you may have to refresh the font cache to use
them in applications. The same applies when applications installed via
Guix do not seem to find fonts. To force rebuilding of the font cache
run @code{fc-cache -f}. The @code{fc-cache} command is provided by the
@code{fontconfig} package.
@subsection X.509 Certificates
The @code{nss-certs} package provides X.509 certificates, which allow
programs to authenticate Web servers accessed over HTTPS.
When using Guix on a foreign distro, you can install this package and
define the relevant environment variables so that packages know where to
look for certificates. @xref{X.509 Certificates}, for detailed
information.
@subsection Emacs Packages
When you install Emacs packages with Guix, the elisp files may be placed
either in @file{$HOME/.guix-profile/share/emacs/site-lisp/} or in
sub-directories of
@file{$HOME/.guix-profile/share/emacs/site-lisp/guix.d/}. The latter
directory exists because potentially there may exist thousands of Emacs
packages and storing all their files in a single directory may be not
reliable (because of name conflicts). So we think using a separate
directory for each package is a good idea. It is very similar to how
the Emacs package system organizes the file structure (@pxref{Package
Files,,, emacs, The GNU Emacs Manual}).
By default, Emacs (installed with Guix) ``knows'' where these packages
are placed, so you do not need to perform any configuration. If, for
some reason, you want to avoid auto-loading Emacs packages installed
with Guix, you can do so by running Emacs with @code{--no-site-file}
option (@pxref{Init File,,, emacs, The GNU Emacs Manual}).
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@subsection The GCC toolchain
@cindex GCC
@cindex ld-wrapper
Guix offers individual compiler packages such as @code{gcc} but if you
are in need of a complete toolchain for compiling and linking source
code what you really want is the @code{gcc-toolchain} package. This
package provides a complete GCC toolchain for C/C++ development,
including GCC itself, the GNU C Library (headers and binaries, plus
debugging symbols in the @code{debug} output), Binutils, and a linker
wrapper.
@cindex attempt to use impure library, error message
The wrapper's purpose is to inspect the @code{-L} and @code{-l} switches
passed to the linker, add corresponding @code{-rpath} arguments, and
invoke the actual linker with this new set of arguments. By default,
the linker wrapper refuses to link to libraries outside the store to
ensure ``purity''. This can be annoying when using the toolchain to
link with local libraries. To allow references to libraries outside the
store you need to define the environment variable
@code{GUIX_LD_WRAPPER_ALLOW_IMPURITIES}.
@c *********************************************************************
@node Package Management
@chapter Package Management
The purpose of GNU Guix is to allow users to easily install, upgrade, and
remove software packages, without having to know about their build
procedures or dependencies. Guix also goes beyond this obvious set of
This chapter describes the main features of Guix, as well as the
package management tools it provides. Along with the command-line
interface described below (@pxref{Invoking guix package, @code{guix
package}}), you may also use Emacs Interface (@pxref{Top,,,
emacs-guix, The Emacs-Guix Reference Manual}), after installing
@code{emacs-guix} package (run @kbd{M-x guix-help} command to start
with it):
@example
guix package -i emacs-guix
@end example
@menu
* Features:: How Guix will make your life brighter.
* Invoking guix package:: Package installation, removal, etc.
* Substitutes:: Downloading pre-built binaries.
* Packages with Multiple Outputs:: Single source package, multiple outputs.
* Invoking guix gc:: Running the garbage collector.
* Invoking guix pull:: Fetching the latest Guix and distribution.
* Invoking guix archive:: Exporting and importing store files.
@end menu
@node Features
@section Features
When using Guix, each package ends up in the @dfn{package store}, in its
own directory---something that resembles
@file{/gnu/store/xxx-package-1.2}, where @code{xxx} is a base32 string.
Instead of referring to these directories, users have their own
@dfn{profile}, which points to the packages that they actually want to
use. These profiles are stored within each user's home directory, at
@code{$HOME/.guix-profile}.
For example, @code{alice} installs GCC 4.7.2. As a result,
@file{/home/alice/.guix-profile/bin/gcc} points to
@file{/gnu/store/@dots{}-gcc-4.7.2/bin/gcc}. Now, on the same machine,
@code{bob} had already installed GCC 4.8.0. The profile of @code{bob}
simply continues to point to
@file{/gnu/store/@dots{}-gcc-4.8.0/bin/gcc}---i.e., both versions of GCC
coexist on the same system without any interference.
The @command{guix package} command is the central tool to manage
packages (@pxref{Invoking guix package}). It operates on the per-user
profiles, and can be used @emph{with normal user privileges}.
The command provides the obvious install, remove, and upgrade
operations. Each invocation is actually a @emph{transaction}: either
the specified operation succeeds, or nothing happens. Thus, if the
@command{guix package} process is terminated during the transaction,
or if a power outage occurs during the transaction, then the user's
profile remains in its previous state, and remains usable.
In addition, any package transaction may be @emph{rolled back}. So, if,
for example, an upgrade installs a new version of a package that turns
out to have a serious bug, users may roll back to the previous instance
of their profile, which was known to work well. Similarly, the global
system configuration on GuixSD is subject to
transactional upgrades and roll-back
(@pxref{Using the Configuration System}).
All packages in the package store may be @emph{garbage-collected}.
Guix can determine which packages are still referenced by user
profiles, and remove those that are provably no longer referenced
(@pxref{Invoking guix gc}). Users may also explicitly remove old
generations of their profile so that the packages they refer to can be
collected.
@cindex reproducibility
@cindex reproducible builds
Finally, Guix takes a @dfn{purely functional} approach to package
management, as described in the introduction (@pxref{Introduction}).
Each @file{/gnu/store} package directory name contains a hash of all the
inputs that were used to build that package---compiler, libraries, build
scripts, etc. This direct correspondence allows users to make sure a
given package installation matches the current state of their
distribution. It also helps maximize @dfn{build reproducibility}:
thanks to the isolated build environments that are used, a given build
is likely to yield bit-identical files when performed on different
machines (@pxref{Invoking guix-daemon, container}).
This foundation allows Guix to support @dfn{transparent binary/source
deployment}. When a pre-built binary for a @file{/gnu/store} item is
available from an external source---a @dfn{substitute}, Guix just
downloads it and unpacks it;
otherwise, it builds the package from source, locally
(@pxref{Substitutes}). Because build results are usually bit-for-bit
reproducible, users do not have to trust servers that provide
substitutes: they can force a local build and @emph{challenge} providers
(@pxref{Invoking guix challenge}).
Control over the build environment is a feature that is also useful for
developers. The @command{guix environment} command allows developers of
a package to quickly set up the right development environment for their
package, without having to manually install the dependencies of the
package into their profile (@pxref{Invoking guix environment}).
@node Invoking guix package
@section Invoking @command{guix package}
@cindex installing packages
@cindex removing packages
@cindex package installation
@cindex package removal
The @command{guix package} command is the tool that allows users to
install, upgrade, and remove packages, as well as rolling back to
previous configurations. It operates only on the user's own profile,
and works with normal user privileges (@pxref{Features}). Its syntax
is:
@example
guix package @var{options}
Primarily, @var{options} specifies the operations to be performed during
the transaction. Upon completion, a new profile is created, but
previous @dfn{generations} of the profile remain available, should the user
want to roll back.
For example, to remove @code{lua} and install @code{guile} and
@code{guile-cairo} in a single transaction:
@example
guix package -r lua -i guile guile-cairo
@end example
@command{guix package} also supports a @dfn{declarative approach}
whereby the user specifies the exact set of packages to be available and
passes it @i{via} the @option{--manifest} option
(@pxref{profile-manifest, @option{--manifest}}).
For each user, a symlink to the user's default profile is automatically
created in @file{$HOME/.guix-profile}. This symlink always points to the
current generation of the user's default profile. Thus, users can add
@file{$HOME/.guix-profile/bin} to their @code{PATH} environment
variable, and so on.
@cindex search paths
If you are not using the Guix System Distribution, consider adding the
following lines to your @file{~/.bash_profile} (@pxref{Bash Startup
Files,,, bash, The GNU Bash Reference Manual}) so that newly-spawned
shells get all the right environment variable definitions:
@example
GUIX_PROFILE="$HOME/.guix-profile" \
source "$HOME/.guix-profile/etc/profile"
@end example
In a multi-user setup, user profiles are stored in a place registered as
a @dfn{garbage-collector root}, which @file{$HOME/.guix-profile} points
to (@pxref{Invoking guix gc}). That directory is normally
@code{@var{localstatedir}/profiles/per-user/@var{user}}, where
@var{localstatedir} is the value passed to @code{configure} as
@code{--localstatedir}, and @var{user} is the user name. The
@file{per-user} directory is created when @command{guix-daemon} is
started, and the @var{user} sub-directory is created by @command{guix
package}.
The @var{options} can be among the following:
@item --install=@var{package} @dots{}
@itemx -i @var{package} @dots{}
Install the specified @var{package}s.
Each @var{package} may specify either a simple package name, such as
@code{guile}, or a package name followed by an at-sign and version number,
such as @code{guile@@1.8.8} or simply @code{guile@@1.8} (in the latter
case, the newest version prefixed by @code{1.8} is selected.)
If no version number is specified, the
newest available version will be selected. In addition, @var{package}
may contain a colon, followed by the name of one of the outputs of the
package, as in @code{gcc:doc} or @code{binutils@@2.22:lib}
(@pxref{Packages with Multiple Outputs}). Packages with a corresponding
name (and optionally version) are searched for among the GNU
distribution modules (@pxref{Package Modules}).
@cindex propagated inputs
Sometimes packages have @dfn{propagated inputs}: these are dependencies
that automatically get installed along with the required package
(@pxref{package-propagated-inputs, @code{propagated-inputs} in
@code{package} objects}, for information about propagated inputs in
package definitions).
An example is the GNU MPC library: its C header files refer to those of
the GNU MPFR library, which in turn refer to those of the GMP library.
Thus, when installing MPC, the MPFR and GMP libraries also get installed
in the profile; removing MPC also removes MPFR and GMP---unless they had
Besides, packages sometimes rely on the definition of environment
variables for their search paths (see explanation of
@code{--search-paths} below). Any missing or possibly incorrect
environment variable definitions are reported here.
@item --install-from-expression=@var{exp}
@itemx -e @var{exp}
Install the package @var{exp} evaluates to.
@var{exp} must be a Scheme expression that evaluates to a
@code{<package>} object. This option is notably useful to disambiguate
between same-named variants of a package, with expressions such as
@code{(@@ (gnu packages base) guile-final)}.
Note that this option installs the first output of the specified
package, which may be insufficient when needing a specific output of a
multiple-output package.
@item --install-from-file=@var{file}
@itemx -f @var{file}
Install the package that the code within @var{file} evaluates to.
As an example, @var{file} might contain a definition like this
(@pxref{Defining Packages}):
@example
@verbatiminclude package-hello.scm
@end example
Developers may find it useful to include such a @file{guix.scm} file
in the root of their project source tree that can be used to test
development snapshots and create reproducible development environments
(@pxref{Invoking guix environment}).
@item --remove=@var{package} @dots{}
@itemx -r @var{package} @dots{}
Remove the specified @var{package}s.
As for @code{--install}, each @var{package} may specify a version number
and/or output name in addition to the package name. For instance,
@code{-r glibc:debug} would remove the @code{debug} output of
@code{glibc}.
@item --upgrade[=@var{regexp} @dots{}]
@itemx -u [@var{regexp} @dots{}]
Upgrade all the installed packages. If one or more @var{regexp}s are
specified, upgrade only installed packages whose name matches a
@var{regexp}. Also see the @code{--do-not-upgrade} option below.
Note that this upgrades package to the latest version of packages found
in the distribution currently installed. To update your distribution,
you should regularly run @command{guix pull} (@pxref{Invoking guix
pull}).
@item --do-not-upgrade[=@var{regexp} @dots{}]
When used together with the @code{--upgrade} option, do @emph{not}
upgrade any packages whose name matches a @var{regexp}. For example, to
upgrade all packages in the current profile except those containing the
substring ``emacs'':
@example
$ guix package --upgrade . --do-not-upgrade emacs
@end example
@item @anchor{profile-manifest}--manifest=@var{file}
@cindex profile declaration
@cindex profile manifest
Create a new generation of the profile from the manifest object
returned by the Scheme code in @var{file}.
This allows you to @emph{declare} the profile's contents rather than
constructing it through a sequence of @code{--install} and similar
commands. The advantage is that @var{file} can be put under version
control, copied to different machines to reproduce the same profile, and
so on.
@c FIXME: Add reference to (guix profile) documentation when available.
@var{file} must return a @dfn{manifest} object, which is roughly a list
of packages:
(use-package-modules guile emacs)
@findex specifications->manifest
In this example we have to know which modules define the @code{emacs}
and @code{guile-2.0} variables to provide the right
@code{use-package-modules} line, which can be cumbersome. We can
instead provide regular package specifications and let
@code{specifications->manifest} look up the corresponding package
objects, like this:
@example
(specifications->manifest
'("emacs" "guile@@2.2" "guile@@2.2:debug"))
@end example
@cindex rolling back
@cindex undoing transactions
@cindex transactions, undoing
Roll back to the previous @dfn{generation} of the profile---i.e., undo
the last transaction.
When combined with options such as @code{--install}, roll back occurs
before any other actions.
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When rolling back from the first generation that actually contains
installed packages, the profile is made to point to the @dfn{zeroth
generation}, which contains no files apart from its own metadata.
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After having rolled back, installing, removing, or upgrading packages
overwrites previous future generations. Thus, the history of the
generations in a profile is always linear.
@item --switch-generation=@var{pattern}
@itemx -S @var{pattern}
Switch to a particular generation defined by @var{pattern}.
@var{pattern} may be either a generation number or a number prefixed
with ``+'' or ``-''. The latter means: move forward/backward by a
specified number of generations. For example, if you want to return to
the latest generation after @code{--roll-back}, use
@code{--switch-generation=+1}.
The difference between @code{--roll-back} and
@code{--switch-generation=-1} is that @code{--switch-generation} will
not make a zeroth generation, so if a specified generation does not
exist, the current generation will not be changed.
@item --search-paths[=@var{kind}]
@cindex search paths
Report environment variable definitions, in Bash syntax, that may be
needed in order to use the set of installed packages. These environment
variables are used to specify @dfn{search paths} for files used by some
of the installed packages.
For example, GCC needs the @code{CPATH} and @code{LIBRARY_PATH}
environment variables to be defined so it can look for headers and
libraries in the user's profile (@pxref{Environment Variables,,, gcc,
Using the GNU Compiler Collection (GCC)}). If GCC and, say, the C
library are installed in the profile, then @code{--search-paths} will
suggest setting these variables to @code{@var{profile}/include} and
@code{@var{profile}/lib}, respectively.
The typical use case is to define these environment variables in the
shell:
@example
$ eval `guix package --search-paths`
@end example
@var{kind} may be one of @code{exact}, @code{prefix}, or @code{suffix},
meaning that the returned environment variable definitions will either
be exact settings, or prefixes or suffixes of the current value of these
variables. When omitted, @var{kind} defaults to @code{exact}.
This option can also be used to compute the @emph{combined} search paths
of several profiles. Consider this example:
@example
$ guix package -p foo -i guile
$ guix package -p bar -i guile-json
$ guix package -p foo -p bar --search-paths
@end example
The last command above reports about the @code{GUILE_LOAD_PATH}
variable, even though, taken individually, neither @file{foo} nor
@file{bar} would lead to that recommendation.
@item --profile=@var{profile}
@itemx -p @var{profile}
Use @var{profile} instead of the user's default profile.
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@item --verbose
Produce verbose output. In particular, emit the build log of the
environment on the standard error port.
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@item --bootstrap
Use the bootstrap Guile to build the profile. This option is only
useful to distribution developers.
@end table
In addition to these actions, @command{guix package} supports the
following options to query the current state of a profile, or the
availability of packages:
@item --search=@var{regexp}
@itemx -s @var{regexp}
@cindex searching for packages
List the available packages whose name, synopsis, or description matches
@var{regexp}, sorted by relevance. Print all the metadata of matching packages in
@code{recutils} format (@pxref{Top, GNU recutils databases,, recutils,
GNU recutils manual}).
This allows specific fields to be extracted using the @command{recsel}
command, for instance:
@example
$ guix package -s malloc | recsel -p name,version,relevance
name: jemalloc
version: 4.5.0
relevance: 6
name: glibc
version: 2.25
relevance: 1
name: libgc
version: 7.6.0
relevance: 1
@end example
Similarly, to show the name of all the packages available under the
terms of the GNU@tie{}LGPL version 3:
@example
$ guix package -s "" | recsel -p name -e 'license ~ "LGPL 3"'
name: elfutils
name: gmp
@dots{}
@end example
It is also possible to refine search results using several @code{-s}
flags. For example, the following command returns a list of board
games:
@example
$ guix package -s '\<board\>' -s game | recsel -p name
name: gnubg
@dots{}
@end example
If we were to omit @code{-s game}, we would also get software packages
that deal with printed circuit boards; removing the angle brackets
around @code{board} would further add packages that have to do with
keyboards.
And now for a more elaborate example. The following command searches
for cryptographic libraries, filters out Haskell, Perl, Python, and Ruby
libraries, and prints the name and synopsis of the matching packages:
@example
$ guix package -s crypto -s library | \
recsel -e '! (name ~ "^(ghc|perl|python|ruby)")' -p name,synopsis
@end example
@noindent
@xref{Selection Expressions,,, recutils, GNU recutils manual}, for more
information on @dfn{selection expressions} for @code{recsel -e}.
@item --show=@var{package}
Show details about @var{package}, taken from the list of available packages, in
@code{recutils} format (@pxref{Top, GNU recutils databases,, recutils, GNU
recutils manual}).
@example
$ guix package --show=python | recsel -p name,version
name: python
version: 2.7.6
name: python
version: 3.3.5
@end example
You may also specify the full name of a package to only get details about a
specific version of it:
@example
$ guix package --show=python@@3.4 | recsel -p name,version
@item --list-installed[=@var{regexp}]
@itemx -I [@var{regexp}]
List the currently installed packages in the specified profile, with the
most recently installed packages shown last. When @var{regexp} is
specified, list only installed packages whose name matches @var{regexp}.
For each installed package, print the following items, separated by
tabs: the package name, its version string, the part of the package that
is installed (for instance, @code{out} for the default output,
@code{include} for its headers, etc.), and the path of this package in
the store.
@item --list-available[=@var{regexp}]
@itemx -A [@var{regexp}]
List packages currently available in the distribution for this system
(@pxref{GNU Distribution}). When @var{regexp} is specified, list only
installed packages whose name matches @var{regexp}.
For each package, print the following items separated by tabs: its name,
its version string, the parts of the package (@pxref{Packages with
Multiple Outputs}), and the source location of its definition.
@item --list-generations[=@var{pattern}]
@itemx -l [@var{pattern}]
Return a list of generations along with their creation dates; for each
generation, show the installed packages, with the most recently
installed packages shown last. Note that the zeroth generation is never
shown.
For each installed package, print the following items, separated by
tabs: the name of a package, its version string, the part of the package
that is installed (@pxref{Packages with Multiple Outputs}), and the
location of this package in the store.
When @var{pattern} is used, the command returns only matching
generations. Valid patterns include:
@itemize
@item @emph{Integers and comma-separated integers}. Both patterns denote
generation numbers. For instance, @code{--list-generations=1} returns
the first one.
And @code{--list-generations=1,8,2} outputs three generations in the
specified order. Neither spaces nor trailing commas are allowed.
@item @emph{Ranges}. @code{--list-generations=2..9} prints the
specified generations and everything in between. Note that the start of
It is also possible to omit the endpoint. For example,
@code{--list-generations=2..}, returns all generations starting from the
second one.
@item @emph{Durations}. You can also get the last @emph{N}@tie{}days, weeks,
or months by passing an integer along with the first letter of the
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duration. For example, @code{--list-generations=20d} lists generations
that are up to 20 days old.
@end itemize
@item --delete-generations[=@var{pattern}]
@itemx -d [@var{pattern}]
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When @var{pattern} is omitted, delete all generations except the current
one.
This command accepts the same patterns as @option{--list-generations}.
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When @var{pattern} is specified, delete the matching generations. When
@var{pattern} specifies a duration, generations @emph{older} than the
specified duration match. For instance, @code{--delete-generations=1m}
deletes generations that are more than one month old.
If the current generation matches, it is @emph{not} deleted. Also, the
zeroth generation is never deleted.
Note that deleting generations prevents rolling back to them.
Consequently, this command must be used with care.
Finally, since @command{guix package} may actually start build
processes, it supports all the common build options (@pxref{Common Build
Options}). It also supports package transformation options, such as
@option{--with-source} (@pxref{Package Transformation Options}).
However, note that package transformations are lost when upgrading; to
preserve transformations across upgrades, you should define your own
package variant in a Guile module and add it to @code{GUIX_PACKAGE_PATH}
(@pxref{Defining Packages}).
@node Substitutes
@section Substitutes
@cindex substitutes
@cindex pre-built binaries
Guix supports transparent source/binary deployment, which means that it
can either build things locally, or download pre-built items from a
server. We call these pre-built items @dfn{substitutes}---they are
substitutes for local build results. In many cases, downloading a
substitute is much faster than building things locally.
Substitutes can be anything resulting from a derivation build
(@pxref{Derivations}). Of course, in the common case, they are
pre-built package binaries, but source tarballs, for instance, which
also result from derivation builds, can be available as substitutes.
The @code{hydra.gnu.org} server is a front-end to a build farm that
builds packages from the GNU distribution continuously for some
architectures, and makes them available as substitutes. This is the
default source of substitutes; it can be overridden by passing the
@option{--substitute-urls} option either to @command{guix-daemon}
(@pxref{daemon-substitute-urls,, @code{guix-daemon --substitute-urls}})
or to client tools such as @command{guix package}
(@pxref{client-substitute-urls,, client @option{--substitute-urls}
option}).
Substitute URLs can be either HTTP or HTTPS.
HTTPS is recommended because communications are encrypted; conversely,
using HTTP makes all communications visible to an eavesdropper, who
could use the information gathered to determine, for instance, whether
your system has unpatched security vulnerabilities.
@cindex security
@cindex digital signatures
@cindex substitutes, authorization thereof
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@cindex access control list (ACL), for substitutes
@cindex ACL (access control list), for substitutes
To allow Guix to download substitutes from @code{hydra.gnu.org} or a
mirror thereof, you
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must add its public key to the access control list (ACL) of archive
imports, using the @command{guix archive} command (@pxref{Invoking guix
archive}). Doing so implies that you trust @code{hydra.gnu.org} to not
be compromised and to serve genuine substitutes.
This public key is installed along with Guix, in
@code{@var{prefix}/share/guix/hydra.gnu.org.pub}, where @var{prefix} is
the installation prefix of Guix. If you installed Guix from source,
make sure you checked the GPG signature of
@file{guix-@value{VERSION}.tar.gz}, which contains this public key file.
Then, you can run something like this:
@example
# guix archive --authorize < hydra.gnu.org.pub
@end example
Once this is in place, the output of a command like @code{guix build}
should change from something like:
@example
$ guix build emacs --dry-run
The following derivations would be built:
/gnu/store/yr7bnx8xwcayd6j95r2clmkdl1qh688w-emacs-24.3.drv
/gnu/store/x8qsh1hlhgjx6cwsjyvybnfv2i37z23w-dbus-1.6.4.tar.gz.drv
/gnu/store/1ixwp12fl950d15h2cj11c73733jay0z-alsa-lib-1.0.27.1.tar.bz2.drv
/gnu/store/nlma1pw0p603fpfiqy7kn4zm105r5dmw-util-linux-2.21.drv
@dots{}
@end example
@noindent
to something like:
@example
$ guix build emacs --dry-run
The following files would be downloaded:
/gnu/store/pk3n22lbq6ydamyymqkkz7i69wiwjiwi-emacs-24.3
/gnu/store/2ygn4ncnhrpr61rssa6z0d9x22si0va3-libjpeg-8d
/gnu/store/71yz6lgx4dazma9dwn2mcjxaah9w77jq-cairo-1.12.16
/gnu/store/7zdhgp0n1518lvfn8mb96sxqfmvqrl7v-libxrender-0.9.7
@dots{}
@end example
@noindent
This indicates that substitutes from @code{hydra.gnu.org} are usable and
will be downloaded, when possible, for future builds.
Ludovic Courtès
committed
Guix detects and raises an error when attempting to use a substitute
that has been tampered with. Likewise, it ignores substitutes that are
not signed, or that are not signed by one of the keys listed in the ACL.
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