Translation(s): English - Italiano - 简体中文
This page provides a brief introduction to the the software available for the stable version of the Debian operating system. More detail is available at the links given below.
The Software Available for Debian's Stable Release
The default Debian install makes a vast amount of software available, all of it easily installable from within Debian itself using the package management tools.1 Historically Debian has had more software2 in its repositories than any other Linux Distribution.
Never the less, for various reasons, Debian's stable version does not include all the software that people find important and many have come to expect. To remedy this there is quite a bit of additional software available for Debian stable, from both official and unofficial sources. This page provides an overview of the most commonly used sources and/or those sources with substantial breadth or depth. The software sources on this page are all either produced by Debian itself or by members of the Debian community for Debian3 so, crucially, all of the software described here is supported by the Debian community at large. More narrowly focused or obscure sources of Debian software, and sources from outside the Debian community, may be found on the page of UnofficialRepositories.
- The Software Available for Debian's Stable Release
Notes Regarding Security
The Debian project provides the highest level of security support to the free software included in the Debian stable release. The official, semi-official, and non-official software sources listed herein may or may not receive this level of security support.
Security Updates of Existing Software
It is worth mentioning that Debian provides timely security updates but that the default install does not ensure that these updates are automatically installed as they become available. An essential part of administering a Debian system is ensuring that security updates happen.
A Debian system is pre-configured to receive security updates when manually requested to do so. The default desktop (gnome) provides a button in the menu bar which installs security updates. Others may need to run (as root)
on a regular basis. Packages are available which install security updates automatically.
Software That Addresses Installation Problems
Because Debian's stable release changes minimally after release the stock version may not install on the newest hardware. For that situation see http://kmuto.jp/debian/d-i/ for installers with up-to-date kernels.4
Note also that some hardware requires non-free firmware to work; firmware that is not included as part of the stock Debian installer.5 See the details in the installation instructions, particularly the official installation guide, and obtain help via IRC or other support channels.
Newer Software For Debian Stable
Because Debian's stable release changes minimally after release, and has few changes in months prior to release, the software included is not always the latest and greatest. Those who need newer software but still want the reliability and security of Debian stable can often satisfy their wants with software from backports, http://backports.debian.org.
Backports provide not only newer applications but also newer kernels. Installing a newer kernel is often the best way to solve problematic hardware issues because the newer kernel contains many newer drivers and bug fixes.
If you need something that is not in backports, or something even newer that what's in backports, a good option is to backport the newer package yourself from the Debian sid/unstable release. If the instructions for backporting from sid/unstable are not clear or you need further help the IRC channel can be a good support option. You may also ask there should you need software even newer than that available in sid/unstable.
Backporting (recompiling and repackaging) is the only safe way to install packages from Debian Sid or Debian Testing on a Debian stable system. Do not install such packages without backporting. Attempting to "mix" releases, especially by updating your sources.list file, is a sure way to break your system. Recovery in these cases usually involves restore from backup.
Note that installing the latest software may not be the best way to meet your real needs. IRC, and other support options, may be able to suggest other alternatives that help you accomplish your real goal.
Those using backports, or backporting packages themselves, should be remember that security updates are no longer automatic!6
Updates to Software for Debian Stable
Some software, such as spam scanners, must be very up-to-date to work. To enable7 updates to the very latest versions of such software, or backports of the important parts, be sure that the releasename-updates ?suite is enabled in /etc/apt/sources.list, by adding releasename-updates to the end of the line. Lines should look something like:8
deb http://http.us.debian.org/debian/ squeeze main squeeze-updates
Prior to the squeeze release such updates were available from Volatile, http://volatile.debian.org/.
Audio and Video Software
Some software is not included in Debian because it is illegal in some parts of the world. Audio and video software can be especially problematic in this regard and the United States is among the more restrictive governments. Mere possession may be a criminal offense and may lead to time in jail. Ignorance of the law is no excuse. This web page should not be considered a substitute for qualified legal advice; legal advice can only be obtained by consulting a lawyer.
Much software related to multi-media, particularly software allowing the playback and manipulation of music, video, and the like, cannot be included in Debian itself for legal reasons. http://debian-multimedia.org/ contains unofficial Debian stable packages of such software.
An alternate approach, one which takes more work but guarantees compatibility with Debian proper9, is to recompile the Debian source package of interest to enable codecs or other features excluded for legal reasons. This is done by downloading the source .deb package with apt-get source packagename, changing the compilation options found in debian/rules, using dpkg --build sourcedirectory to rebuild a binary .deb file, and gdebi packagename to install it. It is a good idea to append +custom.X, where custom is your custom name and X is your private revision number, to the version number defined in the source package's .dsc file to distinguish your re-packaging from stock Debian, and to put the resulting package on hold after installation with aptitude hold packagename so that it is not automatically replaced during system upgrade.
Non-Free Software (e.g. Adobe's Flash)
In accordance with Debian's core principals, those codified in The Debian Social Contract, the default Debian install is configured to install only Free Software. Non-free software is made available to those who wish to risk its ills. Before blindly installing non-free software it may be prudent to ask if there is a Free replacement.10
Access to non-free software distributed by the Debian project is done by modifying the /etc/apt/sources.list file.11 The sources.list man page contains explanations and examples. The basic idea is have the text contrib and non-free appear as components, along with the main component, at the end of each line so that the non-free and contributed software ?suites can also be downloaded from each software archive.
Software for Embedded Devices
A version of Debian, Emdebian, is available for embedded devices, devices with ultra-low capabilities.
Running Debian Without Installing
A computer can run Debian without installing it onto a hard drive; running instead from, say, a CD or a USB stick. The Debian-Live project provides this capability. A "live" version of Debian is no different from an installed version. Software is installed and removed as usual, although whether or not these changes are preserved across reboots depends upon whether the underlying media is writable.
New Debian users should obtain all their software from the Debian repositories. The Debian maintainers have gone to a lot of work to ensure that the software in the Debian repositories works well together and is secure. Getting software from non-Debian sources voids the (non-existent) warranty! The combination of package management systems and the advent Linux distributions which supply vast amounts of software fundamentally changes appropriate system administration practice, especially for the typical user. Do not obtain software from anywhere other than Debian, not even from the software's author, unless you have the skills and the time to solve the resultant problems! Linux newbies are often used to obtaining their software directly from the software's author, as well as from other random places on the Net. This practice contributes to the instability, inflexibility, and insecurity of non-Linux systems. You may think that because you are used to obtaining software from various sources and integrating it into your system that this practice is manageable. Experience suggests otherwise. You are advised to wait until you have navigated several major system upgrades and consider yourself something of a Linux expert before venturing away from the supported Debian software repositories. (1)
In those cases where the software or its configuration has been modified to introduce Debian specific peculiarities these are noted in a README.Debian document found in the package's /usr/share/doc/packagename/ directory. This is usually of interest only to server administrators. (2)
Even the unofficial sources are "officially unofficial" and would be part of Debian itself if the means were available to make it so. These software sources strive to meet Debian's high standards and are engineered to integrate seamlessly into Debian. They are well established and have proven themselves over time. (3)
The kernel, the core of the system, mediates between the rest of the system and most of the hardware. Consequently a newer kernel often is all that's required to support newer hardware. (4)
Unoffical installers exist which contain non-free firmware but there is not a lot of advantage in using them over following the instructions found in the installation guide. See: http://cdimage.debian.org/cdimage/unofficial/non-free/cd-including-firmware/current/ (5)
At the time of this writing the Debian Security Team does not provide support for the software in backports.debian.org, although some software may get security updates from the backport maintainers. (6)
The Debian installer does ask if the releasename-updates suite is to be enabled so it may or may not already be enabled. (7)
Of course there are GUI tools that will make such changes for those afraid of editing text. (8)
Some are less than happy with the quality of debian-multimedia.org. The original quote has been lost but the feeling is captured in this reconstruction of one expert's comment on Debian's IRC support channel: "I would rather gouge my eyes out with blunt toothpicks than let that shit anywhere near my systems." (9)
Regardless, it is much better to obtain non-free software from the official Debian repositories than it is to obtain it from elsewhere on the Internet, even from the software's original source. The software in the Debian repositories has been proven to integrate with Debian and is updated when necessary to maintain security -- in so far as such is possible with non-free software. (10)
Those afraid of typing text into a document can instead use checkboxes found in the graphical interface of the Synaptic package manager. (11)