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Portage (software)
Encyclopedia
Portage is a package management system
used by Gentoo Linux
, based on the concept of ports collection
s. Gentoo is sometimes referred to as a meta-distribution due to the extreme flexibility of Portage, which makes it operating-system
-independent. The Gentoo/Alt
project is concerned with using Portage to manage other operating systems, such as BSDs, Mac OS X
and Solaris. The most notable of these implementations is the Gentoo/FreeBSD
project.
There is an ongoing effort called the Package Manager Specification project (PMS) to standardise and document the behaviour of Portage, allowing the ebuild tree and Gentoo system packages to be used with alternate package managers such as Paludis and pkgcore. Its goal is to specify the exact set of features and behaviour of package managers and ebuilds, serving as an authoritative reference for Portage.
Portage is similar to the BSD
-style package management
known as ports
, and was originally designed with FreeBSD
's ports in mind. Portage is written in the Python programming language
, and is the main utility that defines Gentoo. Although the system itself is known as Portage, it consists of two main parts, the ebuild
system and emerge. The ebuild system takes care of the actual work of building and installing packages, while emerge provides an interface to ebuild: managing an ebuild repository, resolving dependencies and similar issues. (These two therefore have roughly the same relation as rpm
has with yum
, or dpkg
has with APT
.)
Two GTK+
-based GUIs, Porthole and Portato, are available for working with Portage.
There is also the Himerge GUI, which stands for "Haskell Interface for eMerge".
from source code
the packages the user wishes to install. In doing so it allows customization of compiler and target-application options to fit the system's specifications and the user's own wishes. Functionalities related to system management include: allowing parallel package-version installation, tracking cross-package dependencies
, managing a database of installed packages, providing a local ebuild repository, and synchronizing of the local Portage tree with remote repositories. Functionalities related to individual package installation include: specifying compilation settings for the target machine and choosing package components.
Portage distinguishes between three levels of stability in ebuilds: stable (e.g., the software works as intended with no known security issues at time of release), keyword masked (mainly for packages that have not been sufficiently tested
on the target system architecture to be considered stable) and hard masked (broken or very insecure) packages.
The program calculates and manages dependencies, executes ebuilds and maintains the local Portage tree
and database of installed packages. The compilation settings used by ebuilds can be changed through the CFLAGS
environment variable
, based on the specifications of the individual computer and on the user's desire for optimization. The emerge utility executes ebuilds in a sandbox environment. This way the system is protected from software executed by the ebuild and resulting binaries are only merged after a successful build and sandboxed install.
What emerge installs as dependencies is affected by the USE flag-settings. They decide which optional features will be included when installing or upgrading an application. The emerge command can also be used to download and install precompiled binary files.
support, where available, in packages compiled with the flag enabled. The USE flags affect which dependencies
are required, generally affecting which optional features will be built into a given program when it is compiled. For example, in packages which use a configure script, the USE flag
The specification of USE flags is the usual way to configure programs on Gentoo. USE flags may be set manually, or via user-friendly tools such as 'ufed' (USE flag editor), which lists flags along with their description. A list of available USE flags is available in the "Gentoo Linux Use Variable Descriptions" page of the Gentoo website.
s do (like RPM
), employing instead a format known as the ebuild. Whereas RPMs are precompiled binaries, ebuilds are shell script
s with variables and functions which contain a description of the software, and instructions on how to obtain, configure, compile
, and install it, more closely akin to (but more powerful than) the .spec files distributed in SRPMs. There are over 27,000 ebuilds available, the majority of which are distributed by the Gentoo mirrors
. New and updated ebuilds can be obtained by synchronizing the local ebuild repository with the mirrors. This is done by executing the command emerge —-sync. Historically, Gentoo has provided pre-compiled binary packages for many common programs, especially those which are lengthy to compile, such as Mozilla Firefox
and OpenOffice.org
. These are still installed with emerge, just by appending a "-bin" to the package name to instead install the binary version.
with bzip2
compression) with additional metadata
. This feature enables the building of binary packages on one system (using Portage's buildpkg or quickpkg) followed by quick installation on other, identical systems (with Portage's getbinpkg or emerge -K). See Portage Features in the Gentoo Linux Handbook for more information.
Packages that generally just require some testing but will often work fine are said to be keyword masked (i.e. they are available for systems with an ACCEPT_KEYWORDS make.conf entry starting with the character ~, such as ~x86, ~amd64, ~ppc). The standard way to unmask an individual keyword masked package is by adding a file with the full package name and keyword to /etc/portage/package.keywords/. Users can make subdirectories here as well, allowing for custom organization. For example, if a masked package had multiple masked dependencies, the user could make a directory with the name of the original masked package, and put all the mask files for the package and its dependencies in that directory. This scheme replaces the older scheme of having /etc/portage/package.keywords as a text file list.
Packages with known problems or not considered mature enough to be candidates for stable are hard masked by one of the various package.mask files in /usr/portage/profiles, and such entries are generally accompanied by a comment from developers explaining the reason for the mask.
Unofficial documentation
Similar software
Package management system
In software, a package management system, also called package manager, is a collection of software tools to automate the process of installing, upgrading, configuring, and removing software packages for a computer's operating system in a consistent manner...
used by Gentoo Linux
Gentoo Linux
Gentoo Linux is a computer operating system built on top of the Linux kernel and based on the Portage package management system. It is distributed as free and open source software. Unlike a conventional software distribution, the user compiles the source code locally according to their chosen...
, based on the concept of ports collection
Ports collection
Ports collections are the sets of makefiles and patches provided by the BSD-based operating systems, FreeBSD, NetBSD, and OpenBSD, as a simple method of installing software or creating binary packages...
s. Gentoo is sometimes referred to as a meta-distribution due to the extreme flexibility of Portage, which makes it operating-system
Operating system
An operating system is a set of programs that manage computer hardware resources and provide common services for application software. The operating system is the most important type of system software in a computer system...
-independent. The Gentoo/Alt
Gentoo/Alt
Gentoo/Alt is a Gentoo Linux project created to manage porting the Portage framework and other features to other operating systems, such as Mac OS X and the free BSDs...
project is concerned with using Portage to manage other operating systems, such as BSDs, Mac OS X
Mac OS X
Mac OS X is a series of Unix-based operating systems and graphical user interfaces developed, marketed, and sold by Apple Inc. Since 2002, has been included with all new Macintosh computer systems...
and Solaris. The most notable of these implementations is the Gentoo/FreeBSD
Gentoo/FreeBSD
Gentoo/FreeBSD is a Unix-like operating system developed by Gentoo Linux developers in order to bring Gentoo Linux design, structure, and tools such as Portage and the Gentoo Linux baselayout to the FreeBSD operating system...
project.
There is an ongoing effort called the Package Manager Specification project (PMS) to standardise and document the behaviour of Portage, allowing the ebuild tree and Gentoo system packages to be used with alternate package managers such as Paludis and pkgcore. Its goal is to specify the exact set of features and behaviour of package managers and ebuilds, serving as an authoritative reference for Portage.
Accessing Portage
Berkeley Software Distribution
Berkeley Software Distribution is a Unix operating system derivative developed and distributed by the Computer Systems Research Group of the University of California, Berkeley, from 1977 to 1995...
-style package management
Package management system
In software, a package management system, also called package manager, is a collection of software tools to automate the process of installing, upgrading, configuring, and removing software packages for a computer's operating system in a consistent manner...
known as ports
Ports collection
Ports collections are the sets of makefiles and patches provided by the BSD-based operating systems, FreeBSD, NetBSD, and OpenBSD, as a simple method of installing software or creating binary packages...
, and was originally designed with FreeBSD
FreeBSD
FreeBSD is a free Unix-like operating system descended from AT&T UNIX via BSD UNIX. Although for legal reasons FreeBSD cannot be called “UNIX”, as the direct descendant of BSD UNIX , FreeBSD’s internals and system APIs are UNIX-compliant...
's ports in mind. Portage is written in the Python programming language
Python (programming language)
Python is a general-purpose, high-level programming language whose design philosophy emphasizes code readability. Python claims to "[combine] remarkable power with very clear syntax", and its standard library is large and comprehensive...
, and is the main utility that defines Gentoo. Although the system itself is known as Portage, it consists of two main parts, the ebuild
Ebuild
An ebuild is a specialized bash script format created by the Gentoo Linux project for use in its Portage software management system, which automates compilation and installation procedures for software packages....
system and emerge. The ebuild system takes care of the actual work of building and installing packages, while emerge provides an interface to ebuild: managing an ebuild repository, resolving dependencies and similar issues. (These two therefore have roughly the same relation as rpm
RPM Package Manager
RPM Package Manager is a package management system. The name RPM variously refers to the .rpm file format, files in this format, software packaged in such files, and the package manager itself...
has with yum
Yellow dog Updater, Modified
The Yellowdog Updater, Modified is an open-source command-line package-management utility for RPM-compatible Linux operating systems and has been released under the GNU General Public License. It was developed by Seth Vidal and a group of volunteer programmers...
, or dpkg
Dpkg
dpkg is the software at the base of the Debian package management system. dpkg is used to install, remove, and provide information about .deb packages....
has with APT
Advanced Packaging Tool
The Advanced Packaging Tool, or APT, is a free user interface that works with core libraries to handle the installation and removal of software on the Debian GNU/Linux distribution and its variants...
.)
Two GTK+
GTK+
GTK+ is a cross-platform widget toolkit for creating graphical user interfaces. It is licensed under the terms of the GNU LGPL, allowing both free and proprietary software to use it. It is one of the most popular toolkits for the X Window System, along with Qt.The name GTK+ originates from GTK;...
-based GUIs, Porthole and Portato, are available for working with Portage.
There is also the Himerge GUI, which stands for "Haskell Interface for eMerge".
Functions provided
Portage is characterized by its main function: compilingCompiler
A compiler is a computer program that transforms source code written in a programming language into another computer language...
from source code
Source code
In computer science, source code is text written using the format and syntax of the programming language that it is being written in. Such a language is specially designed to facilitate the work of computer programmers, who specify the actions to be performed by a computer mostly by writing source...
the packages the user wishes to install. In doing so it allows customization of compiler and target-application options to fit the system's specifications and the user's own wishes. Functionalities related to system management include: allowing parallel package-version installation, tracking cross-package dependencies
Coupling (computer science)
In computer science, coupling or dependency is the degree to which each program module relies on each one of the other modules.Coupling is usually contrasted with cohesion. Low coupling often correlates with high cohesion, and vice versa...
, managing a database of installed packages, providing a local ebuild repository, and synchronizing of the local Portage tree with remote repositories. Functionalities related to individual package installation include: specifying compilation settings for the target machine and choosing package components.
Portage distinguishes between three levels of stability in ebuilds: stable (e.g., the software works as intended with no known security issues at time of release), keyword masked (mainly for packages that have not been sufficiently tested
Software testing
Software testing is an investigation conducted to provide stakeholders with information about the quality of the product or service under test. Software testing can also provide an objective, independent view of the software to allow the business to appreciate and understand the risks of software...
on the target system architecture to be considered stable) and hard masked (broken or very insecure) packages.
Emerge
The emerge command-line tool is the heart of Portage. The command is customizable with many options and modifiers. The emerge tool is the most important utility for accessing the features of Portage from the command line.The program calculates and manages dependencies, executes ebuilds and maintains the local Portage tree
Tree structure
A tree structure is a way of representing the hierarchical nature of a structure in a graphical form. It is named a "tree structure" because the classic representation resembles a tree, even though the chart is generally upside down compared to an actual tree, with the "root" at the top and the...
and database of installed packages. The compilation settings used by ebuilds can be changed through the CFLAGS
CFLAGS
CFLAGS and CXXFLAGS are either the name of environment variables or of Makefile variables that can be set to specify additional switches to be passed to a compiler in the process of building computer software....
environment variable
Environment variable
Environment variables are a set of dynamic named values that can affect the way running processes will behave on a computer.They can be said in some sense to create the operating environment in which a process runs...
, based on the specifications of the individual computer and on the user's desire for optimization. The emerge utility executes ebuilds in a sandbox environment. This way the system is protected from software executed by the ebuild and resulting binaries are only merged after a successful build and sandboxed install.
What emerge installs as dependencies is affected by the USE flag-settings. They decide which optional features will be included when installing or upgrading an application. The emerge command can also be used to download and install precompiled binary files.
USE flags
The Portage system offers the use of "USE flags", which allows users to indicate which software features they would like to include (and exclude) while building packages. For example, there is a USE flag to include DVDDVD
A DVD is an optical disc storage media format, invented and developed by Philips, Sony, Toshiba, and Panasonic in 1995. DVDs offer higher storage capacity than Compact Discs while having the same dimensions....
support, where available, in packages compiled with the flag enabled. The USE flags affect which dependencies
Coupling (computer science)
In computer science, coupling or dependency is the degree to which each program module relies on each one of the other modules.Coupling is usually contrasted with cohesion. Low coupling often correlates with high cohesion, and vice versa...
are required, generally affecting which optional features will be built into a given program when it is compiled. For example, in packages which use a configure script, the USE flag
feature would translate to ./configure --with-feature.The specification of USE flags is the usual way to configure programs on Gentoo. USE flags may be set manually, or via user-friendly tools such as 'ufed' (USE flag editor), which lists flags along with their description. A list of available USE flags is available in the "Gentoo Linux Use Variable Descriptions" page of the Gentoo website.
ebuild
Gentoo does not, by default, use binary packages as other package management systemPackage management system
In software, a package management system, also called package manager, is a collection of software tools to automate the process of installing, upgrading, configuring, and removing software packages for a computer's operating system in a consistent manner...
s do (like RPM
RPM Package Manager
RPM Package Manager is a package management system. The name RPM variously refers to the .rpm file format, files in this format, software packaged in such files, and the package manager itself...
), employing instead a format known as the ebuild. Whereas RPMs are precompiled binaries, ebuilds are shell script
Shell script
A shell script is a script written for the shell, or command line interpreter, of an operating system. It is often considered a simple domain-specific programming language...
s with variables and functions which contain a description of the software, and instructions on how to obtain, configure, compile
Compile
Compile may refer to:* Compile , a Japanese video game company founded in 1983 that specialized in shoot 'em up and computer puzzle game genres...
, and install it, more closely akin to (but more powerful than) the .spec files distributed in SRPMs. There are over 27,000 ebuilds available, the majority of which are distributed by the Gentoo mirrors
Mirror (computing)
In computing, a mirror is an exact copy of a data set. On the Internet, a mirror site is an exact copy of another Internet site.Mirror sites are most commonly used to provide multiple sources of the same information, and are of particular value as a way of providing reliable access to large downloads...
. New and updated ebuilds can be obtained by synchronizing the local ebuild repository with the mirrors. This is done by executing the command emerge —-sync. Historically, Gentoo has provided pre-compiled binary packages for many common programs, especially those which are lengthy to compile, such as Mozilla Firefox
Mozilla Firefox
Mozilla Firefox is a free and open source web browser descended from the Mozilla Application Suite and managed by Mozilla Corporation. , Firefox is the second most widely used browser, with approximately 25% of worldwide usage share of web browsers...
and OpenOffice.org
OpenOffice.org
OpenOffice.org, commonly known as OOo or OpenOffice, is an open-source application suite whose main components are for word processing, spreadsheets, presentations, graphics, and databases. OpenOffice is available for a number of different computer operating systems, is distributed as free software...
. These are still installed with emerge, just by appending a "-bin" to the package name to instead install the binary version.
Binary packages
Gentoo does have a binary packaging format, which is a .tbz2 file (tarTar (file format)
In computing, tar is both a file format and the name of a program used to handle such files...
with bzip2
Bzip2
bzip2 is a free and open source implementation of the Burrows–Wheeler algorithm. It is developed and maintained by Julian Seward. Seward made the first public release of bzip2, version 0.15, in July 1996.-Compression efficiency:...
compression) with additional metadata
Metadata
The term metadata is an ambiguous term which is used for two fundamentally different concepts . Although the expression "data about data" is often used, it does not apply to both in the same way. Structural metadata, the design and specification of data structures, cannot be about data, because at...
. This feature enables the building of binary packages on one system (using Portage's buildpkg or quickpkg) followed by quick installation on other, identical systems (with Portage's getbinpkg or emerge -K). See Portage Features in the Gentoo Linux Handbook for more information.
Masking
Masking is how Gentoo determines which packages are suitable for a system. Ebuilds designed for different architectures or experimental software are usually masked in a manner which prevents a stable system from installing them without user intervention.Packages that generally just require some testing but will often work fine are said to be keyword masked (i.e. they are available for systems with an ACCEPT_KEYWORDS make.conf entry starting with the character ~, such as ~x86, ~amd64, ~ppc). The standard way to unmask an individual keyword masked package is by adding a file with the full package name and keyword to /etc/portage/package.keywords/. Users can make subdirectories here as well, allowing for custom organization. For example, if a masked package had multiple masked dependencies, the user could make a directory with the name of the original masked package, and put all the mask files for the package and its dependencies in that directory. This scheme replaces the older scheme of having /etc/portage/package.keywords as a text file list.
Packages with known problems or not considered mature enough to be candidates for stable are hard masked by one of the various package.mask files in /usr/portage/profiles, and such entries are generally accompanied by a comment from developers explaining the reason for the mask.
External links
Official documentation- Gentoo Portage Features
- Gentoo Portage Introduction
- Working with Portage
- Gentoo Packages, information about currently available ebuilds
Unofficial documentation
- Gentoo-Portage, alternate presentation of current ebuild information
- Using Portage
- Installing portage on other Linux distros
Similar software
- Emerde, portage-like project for Slackware
- Pkgcore, bsd re-implementation of portage
- Paludis, another package manager that uses ebuilds
- Arch Build System a ports-like system for Arch Linux