Debian
From Wikipedia, the free encyclopedia.
Debian, fully the Debian Project, is a widely used free operating system developed by a group of volunteers from around the world. Currently, the main, released system, Debian GNU/Linux, uses the Linux kernel with many basic tools of the operating system from the GNU project, hence the name GNU/Linux.
Debian is especially well-known for its package management system, based on .deb packages handled by the dpkg and APT programs, which allows relatively painless upgrades from older versions of Debian, nearly effortless installs of new packages, and clean removal of old ones.
Debian is also known for its adherence to the Unix and Free Software philosophies, and its plethora of choice: currently, the organization releases thousands of software packages for eleven processor architectures.
The Debian Project describes Debian as "The Universal Operating System", because Debian isn't an ordinary Linux distribution: it encompasses portss to other kernels such as the Hurd, FreeBSD, and NetBSD. Those ports still haven't been officially released, so it's still accurate to describe Debian as a "GNU/Linux distribution", without further qualifications at this time.
Debian has eleven released GNU/Linux ports, ranging from the ARM processors commonly found in handheld systems up to the IBM s390 mainframes, but of course also including the more common x86 and PowerPC architectures; see Debian's ports page for a full list.
Debian is supported by donations through Software in the Public Interest (SPI Inc.), a non-profit umbrella organization for free software projects.
History
Debian was founded in 1993 by Ian Murdock, then a university student, who wrote the Debian Manifesto which called for the creation of a Linux distribution to be maintained in an open manner, in the spirit of Linux and GNU.
He chose the name Debian by combining his first name and the first name of his then girlfriend (now wife) Debra[1], i.e. the word is a portmanteau. The word "Debian" is pronounced as the corresponding syllables of these names are in American English: /deb' ē ən/.
The Debian Project slowly grew and released its first 0.9x versions in 1994 and 1995, at which point dpkg came into prominence. The first ports to other architectures started being made in 1995, and the first 1.x release of Debian happened in 1996.
Bruce Perens replaced Ian Murdock as the project leader. He initiated the creation of several important documents (the social contract and the accompanying free software guidelines) and the legal umbrella organization (SPI), as well as led the project through the ELF/libc5 releases (1.1, 1.2, 1.3).
Bruce Perens left in 1998 before the release of the first glibc-based Debian, 2.0. The Project proceeded to elect new leaders and make two more 2.x releases, each including more ports and more packages. APT was deployed during this time and the Debian GNU/Hurd was started as well.
The year 1999 brought the first other Linux distributions based on Debian, Corel Linux and Stormix's Storm Linux, neither of which is developed any more but which started what is now a notable trend of basing distributions on Debian.
In late 2000, the project switched to the use of the package pools and the "testing" distribution, marking a major change in archive and release management. In 2001, the developers began holding an annual conference, Debconf, with talks, workshops, and technical users welcome. The 3.0 release of 2002 included more than double the number of packages of the previous release and supported five new architectures.
Debian celebrated its tenth anniversary on August 16, 2003, with many birthday parties held around the world.
- See A Brief History of Debian for a more comprehensive history.
Debian Releases
The latest released version of Debian is called stable. As of 2003, the stable release has version 3.0. In addition, a stable release gets minor updates (the so-called point releases) marked e.g. 3.0r1.
The code names of Debian releases are the names of characters from the movie Toy Story:
- 3.1* -- sarge, anticipated in 2004
- 3.0 -- woody, July 19th, 2002
- 2.2 -- potato, August 15th, 2000
- 2.1 -- slink, March 9th, 1999
- 2.0 -- hamm, July 24th, 1998
- 1.3 -- bo, June 2nd, 1997
- 1.2 -- rex, 1996
- 1.1 -- buzz, 1996
*tentative designationBecause a CD vendor made an unofficial and broken release labelled "1.0", the Project skipped a "1.0" release in order to avoid confusion.
The release after 3.0 is codenamed sarge. The version number is yet to be determined, but will likely be 3.1. It is currently in a state called "testing", which is a staging area for the next release. The day-to-day development takes place in the "unstable" branch which is permanently codenamed sid[2], after the boy next door who broke toys.
Note that software in the "unstable" branch is not necessarily unstable, only that the packaging and other Debian-specific modifications may be new and untested. Software which is itself unstable is generally placed in "experimental".
Project Organization
The Debian Project is a volunteer organization with three foundational documents:
- The Debian Social Contract which defines a set of basic principles by which the members conduct themselves;
- The Debian Free Software Guidelines, which clarify what is meant by the term "free software", prominently featured in the Social Contract;
- The Debian Constitution, which describes the organizational structure for formal decision-making within the Project, and enumerates the powers and responsibilities of the Debian Project Leader, the Debian Project Secretary, and the Debian Developers generally.
Developers use many mailing lists to discuss topics of interest, resolve issues and form common policies. They also use a public bug tracking system, both for issues with packages and for problems with project infrastructure or policies.
A Project Leader is elected once per year by a vote of the Developers. The Debian Project Leader has several special powers, but this power is far from absolute and is rarely utilized. The leader can be recalled, or a decision reversed, by a vote of the developers under the General Resolution process, but again this is seldom done in practice.
The Leader sometimes delegates authority to other developers in order for them to perform specialized tasks. Generally this means that a leader delegates someone to start a new group for a new task, and gradually a team gets formed that carries on doing the work and regularly expands or reduces their ranks as they think is best and as the circumstances allow.
Perhaps a more important person to Debian than the Leader is the Release Manager, who sets goals for the next "stable" release, supervises the process, and makes the final decision as to when to release.
A list of many important positions in the Debian Project is available at the Debian organization web page.
Developer Recruitment, Motivation, and Resignation
The Debian Project has a steady influx of applicants wishing to become Developers. These applicants must undergo an elaborate vetting process which establishes their identity, motivation, understanding of the Project's goals (embodied in the Social Contract), and technical competence. More information on the "New Maintainer" process is available at the Debian New Maintainer page.
Debian Developers join the Project for any number of reasons; some that have been cited in the past include:
- a desire to contribute back to the Free Software community (practically all applicants are users of Free Software);
- a desire to see some specific software task accomplished (some view the Debian user community as a valuable testing or proving ground for new software);
- a desire to make, or keep, Free Software competitive with proprietary alternatives;
- a desire to work closely with people that share some of their aptitudes, interests, and goals (there is a very strong sense of community within the Debian Project which some applicants do not experience in their paid jobs);
- a simple enjoyment of the iterative process of software development and maintenance (some developers have a nearly obsessive level of dedication to refinement and enhancement of software).
Debian package life cycle
Each Debian package has a maintainer (typically, only one, but occasionally small teams of developers supervise particularly complex pieces of software). It is the maintainer's responsibility to keep pace with the releases of officially-authored versions of the software (called "upstream"), if any exist, to ensure that the package is compliant with Debian Policy thereby making it work on all machine architectures Debian supports (making it portable), easier to use, more configurable, more secure, and so forth, and finally to field any bug reports in the package reported by its users (who may include other Debian developers).
Periodically, a package maintainer makes a release of a package by uploading it to the "incoming" directory of the Debian package archive (or an "upload queue" which periodically batch-transmits packages to the incoming directory). Package uploads are automatically processed to ensure that the upload is well-formed (all the requisite files are in place) and that the package bears the digital signature -- produced with OpenPGP-compatible software -- of a Debian developer. All Debian developers have public keys. Packages are signed to be able to reject uploads from hostile outsiders to the project, and to permit accountability in the event that a package contains a serious bug, a violation of policy, or malicious code.
If the package in incoming is found to be validly signed and well-formed, it is installed into the archive into an area called the "pool" and distributed every day to hundreds of mirrors worldwide. Initially, all package uploads accepted into the archive are only available in the "unstable" suite of packages, which contains the most up-to-date version of each package.
However, new code is also untried code, and those packages are only distributed with clear disclaimers. For packages to become candidates for the next "stable" release of the Debian distribution, they first need to be included in the "testing" suite. The requirements for a package to be included in "testing" is that it:
- must have been in "unstable" for the appropriate length of time (the exact duration depends on the "urgency" of the upload);
- must not have a greater number of "release-critical" bugs filed against it than the current version in testing. Release-critical bugs are those bugs which are considered serious enough that they make the package unsuitable for release.
- must be compiled for all architectures slated to release;
- must be a package for an architecture that is slated to release (in other words, packages for architectures that aren't scheduled to release with all the rest are never considered for "testing")
- must not depend on versions of any packages which do not meet the above conditions
Periodically, the Release Manager publishes guidelines to the developers in order to ready the release, and in accordance with them eventually decides to make a release. This occurs when all important software is reasonably up-to-date in the release-candidate suite for all architectures for which a release is planned, and when any other goals set by the Release Manager have been met. At that time, all packages in the release-candidate suite ("testing") become part of the released suite ("stable").
It is possible for a package -- particularly an old, stable, and seldom-updated one -- to belong to more than one suite at the same time. The suites are simply collections of pointers into the package "pool" mentioned above.
Footnotes
[1] Free software projects are often personally named, such as Linux, after its creator, or biff, after its creator's dog.
[2] Some refer to sid as an acronym for Still In Development, but this is an unofficial back-formation that is not often used.
Distributions based on Debian
Many distributions are based on Debian; examples include:
- Gnoppix -- live CD, GNOME
- Knoppix -- live CD, KDE
- Morphix -- live CD, GNOME or KDE
- Mepis -- live CD, KDE or GNOME
- Sacix -- live CD, Gnome
- Gibraltar -- Router and firewall
- Impi Linux -- GNOME, South Africa
- LinEx -- GNOME, Extremadura (Spain)
- Skolelinux -- a distribution for schools, KDE or GNOME, Norway
- UserLinux -- GNOME or KDE
- Bonzai Linux (formerly known as miniwoody) -- 180 MB distribution, KDE
- Libranet -- commercial, KDE
- Linspire -- commercial, KDE
- Progeny -- commercial, custom solutions
- Xandros -- commercial, KDE
External links
- Debian Wiki
- Debian Project
- Distrowatch Review
- Installation Manual
- Debian Reference
- Debian Planet
- Installing Debian from a USB key
- Debian Newbie documentation and list
- Debian Project History
- Debian Man pages
- Overview of Debian installers
- Planet Debian (collection of Debian developers' blogs)
- Debian Laptop Distribution - Proposal
- Debian for mobile (cellular) phones
- Debian for PDAs