ebuild

An ebuild is a script used by Gentoo Linux's Portage package management system to automate the building and installation of software. Written as a shell script, an ebuild describes how to fetch, verify, patch, configure, compile, test, and install a specific version of a software package. Ebuilds are designed to be portable and repeatable, enabling consistent builds across systems.

Each ebuild is named after the package and version and resides in a category directory within a repository, such as /usr/portage or a user overlay. It defines metadata variables including DESCRIPTION, HOMEPAGE, SRC_URI, LICENSE, SLOT, IUSE, DEPEND, and RDEPEND. Ebuilds can inherit one or more eclasses using the inherit statement to reuse common functionality. The file also contains functions that implement the build lifecycle, such as src_configure, src_compile, and src_install, with optional hooks like src_prepare, src_test, and pkg_postinst.

The build and installation flow is coordinated by Portage during operations such as emerge. Portage consults the Manifest to verify source digests, fetches sources from SRC_URI, applies patches if needed, and then executes the defined lifecycle functions. The installed files are placed into a temporary image during the build, after which Portage records the package in the local database and optionally creates a binary package. USE flags, SLOT management, and dependencies influence the configuration, compilation, and installation steps.

Ebuilds are maintained in the Gentoo project’s main repository and in community overlays. They are versioned by filename and can be masked or unmasked to control where and how packages are built. Proper maintenance includes updating metadata, regenerating the Manifest, and ensuring compatibility with the installed Portage version and system profiles.