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6.6 Package Modules

From a programming viewpoint, the package definitions of the GNU distribution are provided by Guile modules in the (gnu packages …) name space27 (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 Defining Packages).

The (gnu packages …) module name space is automatically scanned for packages by the command-line tools. For instance, when running guix package -i 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)28. These package definitions will not be visible by default. Users can invoke commands such as guix package and guix build with the -e option so that they know where to find the package. Better yet, they can use the -L option of these commands to make those modules visible (see --load-path), or define the GUIX_PACKAGE_PATH environment variable. This environment variable makes it easy to extend or customize the distribution and is honored by all the user interfaces.

Environment Variable: GUIX_PACKAGE_PATH

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 Bootstrapping.



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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