When you install software on Xubuntu, the package manager automatically downloads the required software packages from a software repository, a location on the Internet that stores collections of packages ready to be downloaded.
There are thousands of programs available to install on Xubuntu. These programs are stored in software repositories and are made freely available for all Xubuntu users. This makes it very easy to install new programs, and it is also very secure because each program you install is built specially for Xubuntu and checked before it is allowed into the repositories.
To organise the software, Xubuntu repositories are categorised into four groups: “Main”, “Restricted”, “Universe”, and “Multiverse”. The rationale used to determine which software goes into which category is based on the level of support that software development teams provide for a program and the level of compliance the program has to the Free Software Philosophy.
The standard Xubuntu Install CD contains some software from the “Main” and “Restricted” categories.
If your system is connected to the Internet, many more software programs are available for installation. For example, the “Universe” and “Multiverse” repositories are only available over the Internet.
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The “Multiverse” repository contains software that has been classified as non-free. This software may not be permitted in some jurisdictions. When installing each package from this repository, you should verify that the laws of your country permit you to use it. Also, this software may not include security updates. |
You can find more information about the Repositories available on the Ubuntu website.
It is possible to add extra repositories, such as those provided by third parties or those for older version of Xubuntu.
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Be careful when installing software from third-party repositories. It may not have been tested with Xubuntu and could cause your system to break. |
Access Software Sources by pressing → → → then press Other Software.
Press
to add a new repository.Enter the APT line for the extra repository. This should be available from the website of the repository or similar, and should look similar to the following:
deb http://ftp.debian.org etch main
Press
and then click to save your changes.You will be notified that the information about available software is out-of-date. Press
.Most software repositories use a GPG key to digitally sign the files they provide, which makes it easy to check that the files have not been tampered with since their creation. In order for apt to be able to check this, you need the public key that corresponds to the signatures. The key should be available for download on the repository's website.
Once you have downloaded the GPG key, import the key by selecting the Authentication tab, clicking on
, and then selecting the GPG key to be imported.Update Manager automatically finds software updates for your computer when they are available. It regularly gathers information on potential updates from a number of online update sources.
Open Software Sources ( → → → ), then click on the Updates tab, you will notice that four update sources are available. An explanation for each of these is provided below:
Important security updates: Updates that fix critical security flaws are made available through this source. It is recommended that all users leave this source enabled (it should be enabled by default).
Recommended updates: Updates that fix serious software problems (which are not security flaws) are made available through this source. Most users will want to leave this source enabled as common and annoying problems are often fixed with these updates.
Pre-released updates: Updates that are currently being tested before being released to everyone are provided through this update source. If you would like to help test new updates (and get fixes for problems more quickly), enable this source. Be aware that these updates may not yet be well tested; it is not recommended that you enable this source unless you are prepared to experience occasional problems.
Unsupported updates: When new versions of popular software are released they are sometimes “back-ported” to an older version of Xubuntu so that users can benefit from new features and fixes for problems. These backports are unsupported, may cause problems when installed and should only be used by people who are in desperate need of a new version of a software package that they know has been backported.