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From a programming viewpoint, the package definitions of the GNU
distribution are provided by Guile modules in the (gnu packages
…)
name space19
(see Guile modules in GNU Guile Reference Manual). For
instance, the (gnu packages emacs)
module exports a variable named
emacs
, which is bound to a <package>
object (see Definindo pacotes).
The (gnu packages …)
module name space is automatically scanned
for packages by the command-line tools. For instance, when running
guix install emacs
, all the (gnu packages …)
modules are
scanned until one that exports a package object whose name is emacs
is found. This package search facility is implemented in the (gnu
packages)
module.
Users can store package definitions in modules with different names—e.g.,
(my-packages emacs)
20. There are two ways to make these package definitions visible to
the user interfaces:
-L
flag of guix package
and other commands
(see Opções de compilação comum), or by setting the GUIX_PACKAGE_PATH
environment variable described below.
guix pull
so that it
pulls from it. A channel is essentially a Git repository containing package
modules. See Canais, for more information on how to define and use
channels.
GUIX_PACKAGE_PATH
works similarly to other search path variables:
This is a colon-separated list of directories to search for additional package modules. Directories listed in this variable take precedence over the own modules of the distribution.
The distribution is fully bootstrapped and self-contained: each
package is built based solely on other packages in the distribution. The
root of this dependency graph is a small set of bootstrap binaries,
provided by the (gnu packages bootstrap)
module. For more
information on bootstrapping, see Inicializando.
Note that packages under the (gnu
packages …)
module name space are not necessarily “GNU packages”.
This module naming scheme follows the usual Guile module naming convention:
gnu
means that these modules are distributed as part of the GNU
system, and packages
identifies modules that define packages.
Note that the file name and module name
must match. For instance, the (my-packages emacs)
module must be
stored in a my-packages/emacs.scm file relative to the load path
specified with --load-path or GUIX_PACKAGE_PATH
.
See Modules and the File System in GNU Guile Reference Manual, for
details.
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