Fedora And Red Hat System Administration/Working with repositories
Repositories of extra software
Fedora Core only includes a core set of packages. For downloading and installing programs or codecs not distributed with Core, there are several repositories available. Packages are generally compatible between third-party repositories, though this has not always been the case. There are also occasional overlaps or packaging errors that cause one package to negatively affect packages distributed from different repositories.
Fedora Core, Fedora Extras and Fedora Legacy are official repositories in this project. Fedora Core is maintained by Red Hat. Fedora Extras is maintained by a group of volunteers and affiliated with the official Fedora Project. Fedora Extras is currently included in the base distribution as a default repository and no extra configuration is required to enable it. Fedora Legacy repository is also included in Fedora Core 5 and above versions but it is not enabled by default.
These repositories are designed to be compatible with Fedora Core although they may not be compatible with each other. Some of the repositories have discontinued active support for earlier versions of Fedora Core but keep the repositories around for the convenience of users with previous versions.
- Livna, a third-party repository maintained by a group of packagers, supporting Fedora Core 5 through 14 (as of June 2010). Since it merged in 2008 with two other package repositories into RPM Fusion, it contains just the libdvdcss-1.2.10-1 package.
- RPMforge, containing the packages of Matthias Saou, Dag Wieers and Dries that were previously available in three different repositories, supporting Fedora Core 1 through 5. RPMforge is compatible with Fedora Extras, similar to Livna.
- FreshRPMS, maintained by Matthias Saou, supporting Fedora Core 1 through 6
- Dag, maintained by Dag Wieers, supporting Fedora Core 1 through 3
- Dries, maintained by Dries Verachtert, supporting Fedora Core 1 through 6
- PlanetCCRMA, maintained by Fernando Lopez-Lezcano, supporting Fedora Core 1 through 5
- kde-redhat, Excellent source for KDE support in Fedora Core maintained by a group of packagers that support Fedora Core. Has updated KDE desktop RPMS, general KDE applications such as Bluetooth support.
- The Grey Sector, containing mostly MPlayer related packages and binary packaged codecs (which have some legal issues). The repository is maintained by the MPlayer developer.
- fedora-xgl, containing packages required to enable Xgl on Fedora.
- dribble, containing packages with a focus on fun software (multimedia, games, emulators). It is recommended that this repository be used with Livna.
- ATrpms, maintained by Axel Thimm and supporting Fedora Core 1 through 6.
- Updates base packages ahead of Core. Some administrators consider it a bad idea to update base packages outside of their official channel.
- ATrpms is also used extensively by Fedora Myth(TV)ology - a popular how-to resource for installing MythTV on Fedora Core, maintained by Jarod Wilson.
Fedora Core, Fedora Extras and Fedora Legacy projects follow the same packaging guidelines in the Fedora project, and they all only maintain packages that are Free, open source software and legally distributable anywhere in the world. Other repositories may have different policies. For example, the Livna project maintains packages that may have legal issues within the United States or can be downloaded only by the end user.
Some repositories also maintain "source-only" packages that require the user to download pre-built binaries that may not be available to the public. The package script then unpacks and repacks the binaries in a format more suitable for deployment on RPM-based systems.
Software update utilities
The main tool to install software from repositories is the command yum. A graphical tool called pirut (available in the upper menu bar with the name "Package Manager") is, together with the update program pup ("Package Update"), part of the standard installation since Fedora Core 5. Since FC6, a new mechanism for updates was added, based on a daemon called yum-updatesd that scans the repositories, and a notification applet called puplet that notifies the user about the new updates.
In addition to these standard tools, two graphical alternatives - Yumex  and Synaptic - are also available, in Extras. There is also Kyum, which provides a graphical frontend for KDE users.
By default, Fedora Core downloads software (including updates) from a randomly-selected mirror. It is possible to install directly from the Fedora Core CDs or DVD, but this requires changes to yum's configuration files (See off-line repositories below). Altering the configuration in this way is also useful when setting up a local mirror (for example on a company intranet), so that downloads can be obtained from there without having to access a mirror on the Internet.
Up until Fedora Core 4, maintainers of some of the extra repositories advocated the use of apt-rpm for update management - being written in C, it uses fewer CPU cycles and is therefore suitable for older computers with slower processors. For Fedora Core 5, a new version of apt is included in Extras which is capable of using native yum metadata and is multi-lib capable. 
Another useful tool to work with repositories is Fedora Helper . It installs and configures the "missing codecs" - MP3 support, for example. It uses the rpm.livna.org repository. Another tool that helps when using different repositories together is Fedora Frog.
If a machine needs to be updated that is not connected to the network, a repository can be created and updated from there. To create such a portable repository do :
- make the directories ./yum, ./yum/base and ./yum/updates. (if you want your local apache to serve as repository of your intranet, do it inside /var/www/html)
- copy all RPMs of your distribution inside ./base
- create the headers of the packets with the command createrepo ./base (use /var/www/html/yum/base if you did set it for Apache)
- download the updates. To do that, look for a real mirror (there is a list of them here ) and rsync with it to pick up changes (they will be stored in the ./updates repository). To rsync use the command rsync -avrt rsync://repository --exclude=debug/ /your-path/yum/updates
To use the off-line repository from a computer you only have to include in the /etc/yum/repos.d directory an entry (a *.repo file like the others already in /etc/yum/repos.d) specifying the path to the repository. You can use ftp, http or a mounted filesystem. In the latter case the repository path should start with "file://".
- FreshRPMs mailing list: (non-)compatibility of repositories
- Livna's maintainers have a policy to not work together with other 3rd party repositories or at least they had this policy when Fedora Extras was Fedora.us
- Matthias Saou explains the compatibility issues between FreshRPMs and Livna
- FreshRPMS, PlanetCCRMA, Dries and DAG (RPMforge.net) build their packages together from the same sources. This ensures much greater cooperation and compatibility and will eventually lead to a merger.
- "RPMforge: Frequently Asked Questions". http://rpmforge.net/user/faq/#compatibility-and-mixing. Retrieved 2006-07-28.