The high-level interface to package definitions is implemented in the
(guix packages) and
(guix build-system) modules. As an
example, the package definition, or recipe, for the GNU Hello
package looks like this:
(define-module (gnu packages hello) #:use-module (guix packages) #:use-module (guix download) #:use-module (guix build-system gnu) #:use-module (guix licenses) #:use-module (gnu packages gawk)) (define-public hello (package (name "hello") (version "2.10") (source (origin (method url-fetch) (uri (string-append "mirror://gnu/hello/hello-" version ".tar.gz")) (sha256 (base32 "0ssi1wpaf7plaswqqjwigppsg5fyh99vdlb9kzl7c9lng89ndq1i")))) (build-system gnu-build-system) (arguments '(#:configure-flags '("--enable-silent-rules"))) (inputs (list gawk)) (synopsis "Hello, GNU world: An example GNU package") (description "Guess what GNU Hello prints!") (home-page "https://www.gnu.org/software/hello/") (license gpl3+)))
Without being a Scheme expert, the reader may have guessed the meaning
of the various fields here. This expression binds the variable
hello to a
<package> object, which is essentially a record
(see Scheme records in GNU Guile Reference Manual).
This package object can be inspected using procedures found in the
(guix packages) module; for instance,
With luck, you may be able to import part or all of the definition of
the package you are interested in from another repository, using the
guix import command (see Invoking
In the example above,
hello is defined in a module of its own,
(gnu packages hello). Technically, this is not strictly
necessary, but it is convenient to do so: all the packages defined in
(gnu packages …) are automatically known to
the command-line tools (see Package Modules).
There are a few points worth noting in the above package definition:
sourcefield of the package is an
originReference, for the complete reference). Here, the
(guix download)is used, meaning that the source is a file to be downloaded over FTP or HTTP.
mirror://gnu prefix instructs
url-fetch to use one of
the GNU mirrors defined in
sha256 field specifies the expected SHA256 hash of the file
being downloaded. It is mandatory, and allows Guix to check the
integrity of the file. The
(base32 …) form introduces the
base32 representation of the hash. You can obtain this information with
guix download (see Invoking
guix download) and
hash (see Invoking
When needed, the
origin form can also have a
listing patches to be applied, and a
snippet field giving a
Scheme expression to modify the source code.
build-systemfield specifies the procedure to build the package (see Build Systems). Here,
gnu-build-systemrepresents the familiar GNU Build System, where packages may be configured, built, and installed with the usual
./configure && make && make check && make installcommand sequence.
When you start packaging non-trivial software, you may need tools to manipulate those build phases, manipulate files, and so on. See Build Utilities, for more on this.
argumentsfield specifies options for the build system (see Build Systems). Here it is interpreted by
gnu-build-systemas a request run configure with the --enable-silent-rules flag.
What about these quote (
') characters? They are Scheme syntax to
introduce a literal list;
' is synonymous with
Sometimes you’ll also see
` (a backquote, synonymous with
, (a comma, synonymous with
See quoting in GNU Guile Reference Manual,
for details. Here the value of the
arguments field is a list of
arguments passed to the build system down the road, as with
apply in GNU Guile Reference
The hash-colon (
#:) sequence defines a Scheme keyword
(see Keywords in GNU Guile Reference Manual), and
#:configure-flags is a keyword used to pass a keyword argument
to the build system (see Coding With Keywords in GNU Guile
inputsfield specifies inputs to the build process—i.e., build-time or run-time dependencies of the package. Here, we add an input, a reference to the
gawkis itself bound to a
Note that GCC, Coreutils, Bash, and other essential tools do not need to
be specified as inputs here. Instead,
gnu-build-system takes care
of ensuring that they are present (see Build Systems).
However, any other dependencies need to be specified in the
inputs field. Any dependency not specified here will simply be
unavailable to the build process, possibly leading to a build failure.
package Reference, for a full description of possible fields.
Going further: Intimidated by the Scheme language or curious about it? The Cookbook has a short section to get started that recaps some of the things shown above and explains the fundamentals. See A Scheme Crash Course in GNU Guix Cookbook, for more information.
Once a package definition is in place, the
package may actually be built using the
guix build command-line
tool (see Invoking
guix build), troubleshooting any build failures
you encounter (see Debugging Build Failures). You can easily jump back to the
package definition using the
guix edit command
See Packaging Guidelines, for
more information on how to test package definitions, and
guix lint, for information on how to check a definition
for style conformance.
Lastly, see Channels, for information
on how to extend the distribution by adding your own package definitions
in a “channel”.
Finally, updating the package definition to a new upstream version
can be partly automated by the
guix refresh command
Behind the scenes, a derivation corresponding to the
object is first computed by the
That derivation is stored in a .drv file under /gnu/store.
The build actions it prescribes may then be realized by using the
build-derivations procedure (see The Store).
<derivation> object of package for system
package must be a valid
<package> object, and system
must be a string denoting the target system type—e.g.,
"x86_64-linux" for an x86_64 Linux-based GNU system. store
must be a connection to the daemon, which operates on the store
(see The Store).
Similarly, it is possible to compute a derivation that cross-builds a package for some other system:
<derivation> object of package cross-built from
system to target.
target must be a valid GNU triplet denoting the target hardware
and operating system, such as
(see Specifying Target Triplets in Autoconf).
Once you have package definitions, you can easily define variants of those packages. See Defining Package Variants, for more on that.