3.8 How to keep a mixed system

People are sometimes interested in using one of the Debian versions as its main system distribution and one or more packages from another branch.

To set up what is your main version of Debian you should edit the /etc/apt/apt.conf (it does not usually exist, create it if you don't have one) to contain the following line:

     APT::Default-Release "version";

Where version is the version of Debian you want to use as the main distribution. The versions you can use are stable, testing and unstable. To install packages from another version, then, you must use APT in the following way:

     # apt-get -t distribution install package

For that to work, though, you need at least one APT source line in your /etc/apt/sources.list for the distribution you want the package from, and the package must exist on that source.

You can also request a specific version of a package using the following sintax:

     # apt-get install package=version

For example, the line below will install version 2.2.4-1 of the nautilus package.:

     # apt-get install nautilus=2.2.4-1

IMPORTANT: the `unstable' version of Debian is the version to which the newest versions of Debian packages are uploaded first. This distribution sees all of the changes that packages go through, both small ones and more drastic ones which affect many packages or the whole system. For this reason, this version of the distribution should not be used by inexperienced users or by those who need proven stability.

The `testing' distribution is not necessarily better than `unstable', because it does not receive security updates quickly. For servers and other production systems stable should always be used.