Debian

Debian (pronounced /ˈdɛbiən/) is a computer operating system composed of software packages released as free and open source software especially under the GNU General Public License and other free software licenses. The primary form, Debian GNU/Linux, which uses the Linux kernel and GNU OS tools, is a popular and influential GNU/Linux distribution. It is distributed with access to repositories containing thousands of software packages ready for installation and use. Debian is known for strict adherence to the Unix and free software philosophies as well as using collaborative software development and testing processes. Debian can be used as a desktop as well as server operating system.

Organization

The Debian Project is governed by the Debian Constitution and the Social Contract which set out the governance structure of the project as well as explicitly stating that the goal of the project is the development of a free operating system. Debian is developed by over one thousand volunteers from around the world and supported by donations through several non-profit organizations around the world. Most important of these is Software in the Public Interest, the owner of the Debian trademark and umbrella organization for various other community free software projects.

Thus, the Debian Project is an independent decentralized organization; it is not backed by a company like other GNU/Linux distributions such as Ubuntu, openSUSE, Fedora, and Mandriva. The cost of developing all the packages included in Debian 4.0 etch (283 million lines of code), using the COCOMO model, has been estimated to be close to US$13 billion. As of April 2, 2009, Ohloh estimates that the codebase of the Debian GNU/Linux project (45 million lines of code), using the COCOMO model, would cost about US$819 million to develop.

Features

Many distributions are based on Debian, including Ubuntu, MEPIS, Dreamlinux, Damn Small Linux, Xandros, Knoppix, BackTrack, Linspire, sidux, Kanotix, Parsix and LinEx, among others.

Debian is known for an abundance of options. The current stable release includes over twenty five thousand software packages for twelve computer architectures. These architectures range from the Intel/AMD 32-bit/64-bit architectures commonly found in personal computers to the ARM architecture commonly found in embedded systems and the IBM eServer zSeries mainframes. Prominent features of Debian are the APT package management system, repositories with large numbers of packages, strict policies regarding packages, and the high quality of releases. These practices allow easy upgrades between releases as well as automated installation and removal of packages.

The Debian standard install makes use of the GNOME desktop environment. It includes popular programs such as OpenOffice.org, Iceweasel (a rebranding of Firefox), Evolution mail, CD/DVD writing programs, music and video players, image viewers and editors, and PDF viewers. There are pre-built CD images for KDE, Xfce and LXDE as well. The remaining discs, which span five DVDs or over thirty CDs, contain all packages currently available and are not necessary for a standard install. Another install method is via a net install CD which is much smaller than a normal install CD/DVD. It contains only the bare essentials needed to start the installer and downloads the packages selected during installation via APT. These CD/DVD images can be freely obtained by web download, BitTorrent, jigdo or buying them from online retailers.

History

1993–1998

Debian was first announced on 16 August 1993 by Ian Murdock. Murdock initially called the system "the Debian Linux Release". Prior to Debian's release, the Softlanding Linux System (SLS) had been the first GNU/Linux distribution compiled from various software packages, and was a popular basis for other distributions in 1993-1994. The perceived poor maintenance and prevalence of bugs in SLS motivated Murdock to launch a new distribution.

In 1993 Murdock also released the Debian Manifesto, outlining his view for the new operating system. In it he called for the creation of a distribution to be maintained in an open manner, in the spirit of Linux and GNU. He formed the name "Debian" as a combination of the first name of his then girlfriend Debra Lynn and his own first name.

The Debian Project grew slowly at first and released the first 0.9x versions in 1994 and 1995. The first ports to other, non-i386 architectures began in 1995, and the first 1.x version of Debian was released in 1996.

In 1996, Bruce Perens replaced Ian Murdock as the project leader. In the same year, fellow developer Ean Schuessler suggested that Debian should establish a social contract with its users. He distilled the resulting discussion on Debian mailing lists into the Debian Social Contract and the Debian Free Software Guidelines, defining fundamental commitments for the development of the distribution. He also initiated the creation of the legal umbrella organization, Software in the Public Interest.

Perens left the project in 1998 before the release of the first glibc-based Debian, 2.0.

1999–2004

The Project elected new leaders and made two more 2.x releases, each including more ports and packages. The Advanced Packaging Tool was deployed during this time and the first port to a non-Linux kernel, Debian GNU/Hurd, was started. The first Linux distributions based on Debian, namely Libranet, Corel Linux and Stormix's Storm Linux, were started in 1999. The 2.2 release in 2000 was dedicated to Joel Klecker, a developer who died of Duchenne muscular dystrophy.

In late 2000, the project made major changes to archive and release management, reorganizing software archive processes with new "package pools" and creating a testing distribution as an ongoing, relatively stable staging area for the next release. In the same year, developers began holding an annual conference called DebConf with talks and workshops for developers and technical users.

In July 2002, the Project released version 3.0, codenamed woody, (after a character in the movie Toy Story, a trend which continues to the present), a stable release which would see relatively few updates until the following release.

The long release cycle employed by the Debian Project during this time drew considerable criticism from the free software community, and this triggered the creation of Ubuntu in 2004, to date one of the most influential Debian forks.

2005–present

The 3.1 sarge release was made in June 2005. There were many major changes in the sarge release, mostly due to the large time it took to freeze and release the distribution. Not only did this release update over 73% of the software shipped in the previous version, but it also included much more software than previous releases, almost doubling in size with 9,000 new packages. A new installer replaced the aging boot-floppies installer with a modular design. This allowed advanced installations (with RAID, XFS and LVM support) including hardware detection, making installations easier for novice users. The installation system also boasted full internationalization support as the software was translated into almost forty languages. An installation manual and comprehensive release notes were released in ten and fifteen different languages respectively. This release included the efforts of the Debian-Edu/Skolelinux, Debian-Med and Debian-Accessibility sub-projects which boosted the number of educational packages and those with a medical affiliation as well as packages designed especially for people with disabilities.

In 2006, as a result of a much-publicized dispute, Mozilla software was rebranded in Debian, with Firefox becoming Iceweasel, Thunderbird becoming Icedove, along with other Mozilla programs. The Mozilla Corporation stated that Debian may not use the Firefox trademark if it distributes Firefox with modifications which have not been approved by the Mozilla Corporation. Two prominent reasons that Debian modifies the Firefox software are to change the artwork, and to provide security patches. Debian Free Software Guidelines consider Mozilla's artwork non-free. Debian provides long term support for older versions of Firefox in the stable release, where Mozilla prefers that old versions are not supported. The software programs developed largely by the Mozilla Corporation were rebranded but the programs' source codes remained the same only with minor differences.

Debian 4.0 (etch) was released April 8, 2007 for the same number of architectures as in sarge. It included the AMD64 port but dropped support for m68k. The m68k port was, however, still available in the unstable distribution. There were around 18,200 binary packages maintained by more than 1,030 Debian developers.

Debian 5.0 (lenny) was released February 14, 2009 after 22 months of development. It includes over 25,000 software packages. Support was added for Marvell's Orion platform and for netbooks such as the Asus Eee PC. The release was dedicated to Thiemo Seufer, an active developer and member of the community who died in a car accident on December 26, 2008.

Project organization

File:Debian-organigram.png

Diagram of the organizational structure of the project

The Debian Project is a volunteer organization with three foundational documents:

• The Debian Social Contract defines a set of basic principles by which the project and its developers conduct affairs.
• The Debian Free Software Guidelines define the criteria for "free software" and thus what software is permissible in the distribution, as referenced in the Social Contract. These guidelines have also been adopted as the basis of the Open Source Definition. Although it can be considered a separate document for all practical purposes, it formally is part of the Social Contract.
• The Debian Constitution 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.

Currently, the project includes more than a thousand developers. Each of them sustains some niche in the project, be it package maintenance, software documentation, maintaining the project infrastructure, quality assurance, or release coordination. Package maintainers have jurisdiction over their own packages, although packages are increasingly co-maintained. Other tasks are usually handled by the domain of smaller, more collaborative groups of developers.

The project maintains official mailing lists and conferences for communication and coordination between developers. For issues with single packages or domains, a public bug tracking system is used by developers and end-users. Informally, Internet Relay Chat channels (primarily on the OFTC and freenode networks) are used for communication among developers and users as well.

Together, the Developers may make binding general decisions by way of a General Resolution or election. All voting is conducted by Cloneproof Schwartz Sequential Dropping, a Condorcet method of voting. A Project Leader is elected once per year by a vote of the Developers; in April 2008, Steve McIntyre was voted into this position, succeeding Sam Hocevar. The Debian Project Leader has several special powers, but this power is far from absolute and is rarely used. Under a General Resolution, the Developers may, among other things, recall the leader, reverse a decision by him or his delegates, and amend the constitution and other foundational documents.

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.

A role in Debian with a similar importance to the Project Leader's is that of a Release Manager. Release Managers set goals for the next release, supervise the processes, and make the final decision as to when to release.

Project leaders

The project has had the following leaders:

1. Ian Murdock (August 1993 – March 1996), founder of the Debian Project
2. Bruce Perens (April 1996 – December 1997)
3. Ian Jackson (January 1998 – December 1998)
4. Wichert Akkerman (January 1999 – March 2001)
5. Ben Collins (April 2001 – April 2002)
6. Bdale Garbee (April 2002 – April 2003)
7. Martin Michlmayr (March 2003 – March 2005)
8. Branden Robinson (April 2005 – April 2006)
9. Anthony Towns (April 2006 – April 2007)
10. Sam Hocevar (April 2007 – April 2008)
11. Steve McIntyre (April 2008 – Present)

A supplemental position, Debian Second in Charge (2IC), was created by Anthony Towns. Steve McIntyre held the position between April 2006 and April 2007. Since April 2009 this position is held by Luk Claes.

Release managers

• Brian C. White (1997–1999)
• Richard Braakman (1999–2000)
• Anthony Towns (2000–2004)
• Steve Langasek, Andreas Barth and Colin Watson (2004–2007)
• Andreas Barth and Luk Claes (2007–2008)
• Luk Claes and Marc Brockschmidt (2008–2009)
• Luk Claes and Adeodato Simó (2009–present)

Note that this list includes the active release managers; it does not include the release assistants (first introduced in 2003) and the retiring managers ("release wizards").

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.

Debian Developers join the Project for a 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

Debian Developers may resign their positions at any time by orphaning the packages they were responsible for and sending a notice to the developers and the keyring maintainer (so that their upload authorization can be revoked).

Development procedures

Software packages in development are either uploaded to the project distribution named unstable (also known as sid), or to the experimental repository. Software packages uploaded to unstable are normally versions stable enough to be released by the original upstream developer, but with the added Debian-specific packaging and other modifications introduced by Debian developers. These additions may be new and untested. Software not ready yet for the unstable distribution is typically placed in the experimental repository.

After a version of a software package has remained in unstable for a certain length of time (depending on the urgency of the software's changes), that package is automatically migrated to the testing distribution. The package's migration to testing occurs only if no serious (release-critical) bugs in the package are reported and if other software needed for package functionality qualifies for inclusion in testing.

Since updates to Debian software packages between official releases do not contain new features, some choose to use the testing and unstable distributions for their newer packages. However, these distributions are less tested than stable, and unstable does not receive timely security updates. In particular, incautious upgrades to working unstable packages can sometimes seriously break software functionality. Since September 9, 2005 the testing distribution's security updates have been provided by the testing security team.

After the packages in testing have matured and the goals for the next release are met, the testing distribution becomes the next stable release. The timing of the release is decided by the Release Managers, and in the past the exact date was rarely announced earlier than a couple of weeks beforehand; however, this is expected to change in 2010 to a release model where times are known in advance.

Package maintenance

File:Debian-package-cycle.png

Flowchart of the life cycle of a Debian package

Each Debian software package has a maintainer who keeps track of releases by the "upstream" authors of the software and ensures that the package is compliant with Debian Policy, coheres with the rest of the distribution, and meets the standards of quality of Debian. In relations with users and other developers, the maintainer uses the bug tracking system to follow up on bug reports and fix bugs. Typically, there is only one maintainer for a single package, but increasingly small teams of developers "co-maintain" larger and more complex packages and groups of packages.

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 they are well-formed (all the requisite files are in place) and that the package is digitally signed by a Debian developer using OpenPGP-compatible software. 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 release architectures the package claims to support (eg: the i386-specific package gmod can be included in "testing")
• All of its dependencies must either be satisfiable by packages already in testing, or be satisfiable by the group of packages which are going to be installed at the same time.
• The operation of installing the package into testing must not break any packages currently in testing.

Thus, a release-critical bug in a package on which many packages depend, such as a shared library, may prevent many packages from entering the "testing" area, because that library is considered deficient.

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.

Security information and policy

The Debian Project, being free software, handles security policy through public disclosure rather than through security through obscurity. Many advisories are coordinated with other free software vendors and are published the same day a vulnerability is made public. Debian has a security audit team that reviews the archive looking for new or unfixed security bugs. Debian also participates in security standardization efforts: the Debian security advisories are compatible with the Common Vulnerabilities and Exposures (CVE) dictionary, and Debian is represented in the Board of the Open Vulnerability and Assessment Language (OVAL) project.

The Debian Project offers extensive documentation and tools to harden a Debian installation both manually and automatically. SELinux (Security-Enhanced Linux) packages are installed by default though not enabled.

Releases

File:Debian-installer.png Debian Installer

As of 2009, the latest stable release is version 5.0, code name lenny. When a new version is released, the previous stable is labeled oldstable; currently, this is version 4.0, code name etch.

In addition, a stable release gets minor updates (called point releases). The numbering scheme for the point releases up to Debian 4.0 was to include the letter r (for release) after the main version number (e.g. 4.0) and then the number of the point release; for example, the latest point release of version 4.0 (etch) as of 8 April 2009 is 4.0r8. From Debian 5.0 (lenny), the numbering scheme of point releases has been changed and conforms to the GNU version numbering standard; so, for example, the first point release of Debian 5.0 was 5.0.1 (instead of 5.0r1).

The Debian security team releases security updates for the latest stable major release, as well as for the previous stable release for one year. Version 4.0 etch was released on 8 April 2007, and the security team supported version 3.1 Sarge until March 31, 2008. For most uses it is strongly recommended to run a system which receives security updates. The testing distribution also receives security updates, but not in as timely a manner as stable.

Once Debian 6.0 is released, a new policy of time-based development freezes on a two-year cycle will come into force. Time-based freezes will allow the Debian Project to blend the predictability of time based releases with its well established policy of feature based releases. The new freeze policy will provide better predictability of releases for users of the Debian distribution, and also allow Debian developers to do better long-term planning. A two-year release cycle will give more time for disruptive changes, reducing inconveniences caused for users. Having predictable freezes should also reduce overall freeze time.

The code names of Debian releases are names of characters from the film Toy Story. The unstable, development distribution is permanently nicknamed sid, after the emotionally unstable next-door neighbor boy who regularly destroyed toys.

Release history

Debian has made ten major stable releases:

Legend
Old release; not supported
Old release; still supported
Current release
Future release

Version	Code name	Release date	Ports	Packages	Support	Notes
1.1	buzz	17 June 1996	1	474	1996[citation needed]	dpkg, ELF transition, Linux 2.0
1.2	rex	12 December 1996	1	848	1996[citation needed]	-
1.3	bo	5 June 1997	1	974	1997[citation needed]	-
2.0	hamm	24 July 1998	2	≈ 1,500	1998	glibc transition, new architecture: m68k
2.1	slink	9 March 1999	4	≈ 2,250	2000-12	APT, new architectures: alpha, sparc
2.2	potato	15 August 2000	6	≈ 3,900	2003-04	New architectures: arm, powerpc
3.0	woody	19 July 2002	11	≈ 8,500	2006-08	New architectures: hppa, ia64, mips, mipsel, s390
3.1	sarge	6 June 2005	11	≈ 15,400	2008-04	Modular installer, semi-official amd64 support.
4.0	etch	8 April 2007	11	≈ 18,000	2010-02	New architecture: amd64, dropped architecture: m68k. Graphical installer, udev transition, modular X.Org transition. Latest update 4.0r8 was released 2009-04-09
5.0	lenny	14 February 2009	11+1Template:Ref label	≈ 23,000	TBA	New architecture/binary ABI: armel. SPARC 32-bit hardware support dropped. Full Eee PC support. Latest update 5.0.4 was released 2010-01-30.
6.0	squeeze	2010	10+2Template:Ref label	TBA	TBA	New architectures/kernels: kfreebsd-i386, kfreebsd-amd64, dropped architectures: alpha, arm. eglibc in favour of glibc.

Template:Note label 11 architectures + 1 additional ARM binary ABI (armel)

Template:Note label 10 architectures with Linux kernel + 2 architectures with FreeBSD kernel

File:Debian-cd-cover1.png A Debian 4.0 Box Cover

Due to an incident involving a CD vendor who made an unofficial and broken release labeled 1.0, an official 1.0 release was never made.

Distributions

The Debian Project offers 3 distributions to choose from, each with different characteristics. The distributions include packages which comply with the Debian Free Software Guidelines (DFSG), which are included inside the main repositories.

• stable, currently aliased lenny, is the current release that has stable and well tested software. Stable is made by freezing testing for a few months where bugs are fixed to make the distribution as stable as possible; then the resulting system is released as stable. It is updated only if major security or usability fixes are incorporated. After Debian 6.0, new releases will be made every two years. Stable's CDs and DVDs can be found in the Debian web site.

• testing, currently aliased squeeze, is what the next major release will be and is currently being tested. The packages included in this distribution have had some testing in unstable but they may not be completely fit for release yet. It contains more modern packages than stable but older than unstable. This distribution is updated continuously until it enters the "frozen" state. Security updates for testing distribution are provided by Debian testing security team. Testing's CDs and DVDs can be found on the Debian web site.

• unstable, permanently aliased sid, repository contains packages currently under development; it is updated continuously. This repository is designed for Debian developers who participate in a project and need the latest libraries available, therefore it will not be as stable as the other distributions. There are no official CDs/DVDs because it is rapidly changing and the project does not support it, although CD and DVD images of sid are built quarterly by sidux. Additionally, the other two distributions can be upgraded to unstable.

Additional repositories

The Debian Free Software Guidelines (DFSG) adhere to a strict interpretation of free and open source software (FOSS). This is why a relatively small number of packages are excluded from the distributions' main repositories and included inside the non-free and contrib repositories. These two repositories are not officially part of Debian GNU/Linux.

• non-free: repositories include packages which do not comply with the DFSG.

• contrib: repositories include packages which do comply with the DFSG, but may fail other requirements. For instance, they may depend on packages which are in non-free.

These are other repositories available in Debian:

• experimental: is not actually a full (self-contained) development distribution, it is meant to be a temporary staging area for highly experimental software. Dependencies missing are most likely found in unstable. Debian warns that these packages are likely unstable or buggy and are to be used at the user's own risk.

• volatile project: repository contains updates to the stable and oldstable release for programs whose functionality requires frequent updates. Some packages aim at fast moving targets, such as spam filtering and virus scanning, and even when using updated data patterns, they do not really work for the full time of a stable release. The main goal of volatile is allowing system administrators to update their systems in a nice, consistent way, without getting the drawbacks of using unstable, even without getting the drawbacks for the selected packages. So debian-volatile will only contain updates to programs that are necessary to keep them functional.

• oldstable, presently aliased etch, is the previous stable release. It is supported until 1 year after a new stable is released. Debian recommends to update to the new stable once it has been released.

Third-party repositories

These repositories are not part of the Debian Project, they are maintained by third party organizations. They contain packages that are either more modern than the ones found in stable or include packages that are not included in the Debian Project for a variety of reasons such as: e.g. alleged possible patent infringement, binary-only/no sources, or special too restrictive licenses. Their use requires precise configuration of the priority of the repositories to be merged; otherwise these packages may not integrate correctly into the system, and may cause problems upgrading or conflicts between packages from different sources. The Debian Project discourages the use of these repositories as they are not part of the project.

Repository access

Debian provides repositories of more than twenty five thousand installable packages. Any of the repositories can be added or modified by directly editing the files in /etc/apt/sources.list.d/ or modifying the settings in APT front-ends. This is an example of the contents of this file:

deb http://http.us.debian.org/debian lenny main contrib non-free

Installation of software packages

dpkg, installing local .deb packages

dpkg is the base of the Debian package management system. dpkg is a command-line utility to install, remove, and provide information about local .deb packages. Gdebi is a tool that expands the functionality of dpkg by not only installing local .deb packages but also fetching and installing dependencies from online repositories. Gdebi can be used both in a graphical interface and by command-line.

APT, installing packages from online repositories

APT expands the functionality of dpkg by searching, fetching and installing packages from online repositories along with their dependencies, either from binary files or by compiling source code. It can also upgrade packages and upgrade the whole distribution to a new release.

File:Add-remove-applications.png Installing and removing software in Debian.

File:Debian-synaptic.png Synaptic: a GUI for APT.

File:Debian-aptitude.png Package installed with aptitude.

Graphical front-ends

• Add/Remove Applications is a GNOME program to install applications.
• Synaptic is a GTK+ front-end for APT.
• KPackage is KDE's front-end for APT.
• Adept is a discontinued KDE front-end for APT.

Command-line front-ends

• aptitude is the preferred front-end for APT.
• apt-get is another front-end for APT with fewer features and worse dependency management than aptitude.
• dselect is an old front-end for APT, largely superseded by other front-ends.
• wajig is a simplified front end, providing the functionality of APT, dpkg, dpkg-deb, apt-cache, and other tools.

Ports

As of the current stable release, the official ports are:

• i386 – x86 architecture designed for Intel/AMD 32-bit PCs. Also compatible but not recommended on Intel/AMD 64-bit single/multi core PCs
• amd64 – x86-64 architecture designed for Intel/AMD 64-bit single/multi core PCs
• alpha – DEC Alpha architecture
• sparc – Sun SPARC architecture on sun4u/v systems
• arm, armel – ARM architecture on Risc PC and various embedded systems (both little-endian – old ABI and EABI)
• powerpc – PowerPC architecture
• hppa – HP PA-RISC architecture
• ia64 – Intel Itanium (IA-64) architecture
• mips, mipsel – MIPS architecture (big-endian and little-endian)
• s390 – IBM ESA/390 architecture and z/Architecture

In addition, in the official testing/unstable distribution are:

• kfreebsd-i386 – FreeBSD kernel on x86 architecture
• kfreebsd-amd64 – FreeBSD kernel on x86-64 architecture
• hurd-i386 – GNU Hurd kernel on x86 architecture

Unofficial ports are available as part of the unstable distribution at http://www.debian-ports.org:

• sh4 – Hitachi SuperH architecture
• avr32 – Atmel AVR32 architecture
• sparc64 – Sun SPARC architecture with 64-bit userland
• m68k – Motorola 68k architecture on Amiga, Atari, Macintosh, and various embedded VME systems

The m68k port was the second official one in Debian, and has been part of five stable Debian releases. Due to its failure to meet the release criteria, it has been dropped before the release of etch.

Kernels

Linux kernel versions

Debian release	Debian Linux kernel	Latest Linux kernel version just before the Debian release
1.1 buzz on 17 June 1996	2.0	2.0.14 on 6 June 1996
1.2 rex on 12 December 1996	2.0.27	2.0.27 on 1 December 1996
1.3 bo on 5 June 1997	2.0.29 2.0.30 for 1.3.1 also 2.0.33	2.0.30 on 8 April 1997 2.1.42 on 29 May 1997
2.0 hamm on 24 July 1998	2.0.33 2.0.34	2.0.35 on 13 July 1998 2.1.110 on 21 July 1998
2.1 slink on 9 March 1999	2.0.35-3 2.0.36-3 2.1.125-1 2.2.1-1	2.2.3 on 9 March 1999
2.2 potato on 15 August 2000	2.2.16	2.2.16 on 7 June 2000 2.3.99-pre9 on 23 May 2000
3.0 woody on 19 July 2002	2.2.20 2.4.18	2.2.21 on 20 May 2002 2.4.18 on 25 February 2002 2.5.26 on 16 July 2002
3.1 sarge on 6 June 2005	2.4.27 2.6.8	2.4.30 on 4 April 2005 2.6.11.11 on 27 May 2005
4.0 etch on 8 April 2007	2.6.18	2.6.20.6 on 6 April 2007
5.0 lenny on 14 February 2009	2.6.26	2.6.28.5 on 12 February 2009

It has been announced (tentatively) that Debian 6.0 "Squeeze" will use kernel version 2.6.32

Non-Linux kernels

For more details on this topic, see GNU variants.

There have been no official stable releases of the non-Linux ports yet, so currently Debian is exclusively a Linux distribution. However, there has been recent development on using the FreeBSD kernel in Debian/kFreeBSD.

Debian Live

A Debian Live system is a version of Debian that can be booted directly from removable media (CDs, DVDs, USB keys) or via netboot without having to install it on the hard drive. This allows the user to try out Debian before installing it or use it as a boot-disk. There are prebuilt Debian Live CD images for rescue, standard, GNOME, KDE, Xfce and LXDE in both i386 and amd64. A hard disk installation can be achieved using the Debian Installer included in the CD. Customized CD images can be built using live-helper. Live-helper can not only generate CD Images, but also bootable DVDs, images for USB thumb drives, or netboot images. Live-magic is a GUI for live-helper. Ging is a Debian GNU/kFreeBSD Live CD.

Desktop environments

Debian offers stable and testing CD images specifically built for GNOME (the default), KDE, Xfce and LXDE. Less common window managers such as Enlightenment, Fluxbox, GNUstep, IceWM, Window Maker and others can also be installed.

Hardware requirements

Debian has no hardware requirements beyond those of the Linux kernel and the GNU tool-sets (gcc, coreutils, bash, etc.). Therefore, any architecture or platform to which these packages have been ported, and for which a Debian port exists, can run Debian.

Linux, and therefore Debian, supports many processors or "symmetric multiprocessing". This does not inhibit support for single-processor systems.

Debian's recommended system requirements differ depending on the level of installation, which corresponds to increased numbers of installed components:

Install Type	Minimal RAM	Recommended RAM	Hard Drive space used
No Desktop	64 MB	256 MB	1 GB
With Desktop	64 MB	512 MB	5 GB

A 1 GHz processor is the minimum recommended for desktop systems.

The real minimum memory requirements are a lot less than the numbers listed in this table. Depending on the architecture, it is possible to install Debian with as little as 20 MB for s390 or 48 MB for i386 and amd64. The same is applicable for disk space requirements which depend on the packages to be installed.

It is possible to run graphical user interfaces on older or low-end systems, but it is recommended to install window managers instead which are less resource-intensive than desktop environments. The LXDE desktop environment was released with lenny and has much lower processor and memory usages compared with GNOME or KDE.

Depending on the nature of the server, RAM and disk space requirements can vary widely.

The release of lenny (5.0) coincided with the release of Emdebian 1.0, which gives much more control over packing Debian for extremely resource-constrained embedded systems. So far only ARM (EABI) is supported for the smallest Crush flavour.

Response

Debian was ranked second only to Ubuntu (which is itself derived from Debian) for Most Used Linux Distribution for both Personal and Organizational use in a 2007 survey by SurveyMonkey.com. Debian won the 2007 poll on Server Distribution of the Year by LinuxQuestions.org.

Both the Debian distribution and their website have won various awards from different organizations. Debian was awarded the 2004 Readers' Choice Award for Favorite Linux Distribution by the Linux Journal. A total of fifteen other awards have been awarded throughout Debian's lifetime including Best Linux Distribution.

Debian has also received negative assessments. In May 2008, a Debian Developer revealed his discovery that changes made in 2006 to the random number generator in the version of the openssl package distributed with Debian and other Debian-based distributions such as Ubuntu or Knoppix, made a variety of security keys vulnerable to a random number generator attack. The security weakness was caused by changes made to the openssl code by another Debian Developer in response to memory debugger warnings. The security hole was soon patched by Debian and others, but the complete resolution procedure was cumbersome for users because it involved regenerating all affected keys, and it drew criticism to Debian's practice of making Debian-specific changes to software.

Richard Stallman and the FSF have criticized the Debian Project for providing the non-free repository, rather than excluding this type of software entirely, an opinion also echoed by some in Debian including the then-Project Leader Wichert Akkerman. The internal dissent in the Debian Project regarding the non-free section has persisted, but the last time it came to a vote in 2006, a large majority decided to keep it.

During the release cycles of Woody and Sarge, the Debian Project drew considerable criticism from the free software community because of the extended period between stable releases. This triggered the creation of Ubuntu in 2004. Ubuntu has releases every 6 months which are forks of Debian's unstable distribution with bug fixes and other modifications. However, it may be more appropriate to compare Debian releases (which continue to be supported after the release of subsequent versions) to Ubuntu's Long Term Support releases (which are supported for three years for desktops and five years for servers); Ubuntu produces a new LTS release every two years, which is therefore similar to Debian's new two-year release cycle for post-Debian 6.0 releases.

When in need of updated versions of software, it is possible to use Debian testing instead of stable as it usually contains more modern, though slightly less stable packages instead of using Ubuntu's Debian-based unstable distribution.

See also

• Comparison of GNU/Linux distributions
• DCC Alliance
• Debian Live
• List of Debian-based GNU/Linux distributions

Notes

• Krafft, Martin F. (2005). The Debian System. U.S.A.: No Starch Press. pp. 608. ISBN 1-59327-069-0. http://www.debiansystem.info. 
• Mako Hill, Benjamin (2005). Debian GNU/Linux 3.1 Bible. John Wiley & Sons. pp. 672. ISBN 0-7645-7644-5. 
• Jurzik, Heike (2005). Debian GNU / Linux. Galileo Press GmbH. pp. 630. ISBN 3898426270. 
• Schoblick, Robert (2005). Debian / GNU Linux. BHV Verlag. pp. 767. ISBN 3826681517. 
• Bellomo, Michael (2000). Debian GNU/Linux for Dummies. Hungry Minds. pp. 324. ISBN 0764507133. 
• McCarty, Bill (1999). Learning Debian GNU/Linux. O'Reilly. pp. 360. ISBN 1565927052. 
• Goerzen, John (1999). Debian Gnu/Linux: Guide to Installation and Usage. New Riders Pub. pp. 158. ISBN 0735709149. 
• Scheetz, Dale (1998). The Debian Linux User's Guide. Linux Press. pp. 268. ISBN 0965957519. 

External links

• Debian official site
• Debian Live official site
• Template:Distrowatch
• Original comp.os.linux.development announcement from 1993
• Debian Project Leader Election 2008 Results
• Scientific study about Debian Project governance and social organization
• List of packages in Debian
• Screenshots of packages in Debian
• #debian on OFTC

Third party repositories

• debian-multimedia.org
• debian-unofficial.org
• dotdeb.org
• backports.org