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DebianReleases > Debian Testing

How Debian Testing Works

Packages from Debian Unstable enter the next-stable testing distribution automatically, when a list of requirements is fulfilled:

For more in depth information see the official Debian Testing web page:

These requirements should assure that the next-stable packages in testing are both reasonably current and in a pretty workable state. Still, sometimes, especially when packages are being restructured, packages that are not quite releasable may get into the next-stable distribution. So, there may remain some of the fun of using a constantly evolving development distribution.

How to use Debian (next-stable) Testing

First thing is to assess the current state of testing. Have a look at the recent topics in the debian-testing mailing list archive and the Status/Testing Wiki-Page. Besides using these specific resources you can also use the general debian-user and debian-devel mailing lists, IRC channels #debian or #debian-next, and of course the debian bug tracker. You may also have a look at the DebianDesktopHowTo.

The reliable way to install testing from scratch is to do a minimal installation with the stable installer, then upgrade from stable to testing.

Alternatively, you could use the testing image of the debian-installer, but note that the testing installer is more for testing the installer than for installing testing. Bugs in the testing installer should be filed against the debian-installer pseudopackage.

To upgrade to testing, if you have already installed the stable release, edit your /etc/apt/sources.list substituting 'stable' (or the current codename for stable) in the apt lines to 'testing' (or the current code name for the next stable release). Additional changes in that file might be required. You may also do this with synaptic.

The code name for the next stable release, e.g. "trixie", will track "trixie" through its transition into "stable" and later old-stable, while "testing" will keep rolling on after a new stable release. If you would rather track the jessie release as it becomes stable, update your /etc/apt/sources.list replacing "stable" or "testing" with "trixie".


If you are tracking testing or the next-stable code name, you should always have a corresponding deb <"testing" or codename>/updates main line in your /etc/apt/sources.list . See this FAQ-Item.

After installing or adjusting the software sources, run apt-get update && apt-get upgrade regularly to get new versions and security updates. If you notice that some packages are not upgraded you should also try apt-get dist-upgrade, but beware that this command will also install or remove packages, so do check carefully all proposed actions before proceeding.


An example of the kinds of temporary breakage that may happen in next-stable testing was the upgrade from perl-5.6.0 to perl-5.6.1 which made perl unable to find its modules if they were from a package built with perl-5.6.0. However, by setting the environment variable PERL5LIB to /usr/lib/perl/5.6.0 manually one could solve the problem even before the fixed package entered testing.

Testing changes more often than stable, but not as crazily as unstable, so expect that new stable versions of the programs you use will be installed as soon as they are ready for next-stable testing, except when testing gets "frozen" to prepare for an imminent stable release. See also DebianStability.

Compared to stable and unstable, next-stable testing has the worst security update speed. Don't prefer testing if security is a concern.

You can see what distribution an alias is tracking by looking at the Release file; e.g.:

If you wonder why a package (or a particular version thereof) is not yet in testing, see

How does ''Testing'' become the new ''Stable'' release ?

see DebianReleaseFAQ.

See also