Debian testing is the current development cycle of Debian.

A package is installed into the testing dist from DebianUnstable automatically when a list of requirements is fulfilled:

These requirements should assure that testing is in a pretty workable state but still developing. Especially when packages get restructured, packages that are not quite releasable get into testing, so not all the fun of using a developmental version is removed.

An example of testing's unstableness is 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. Setting the environment variable ["PERL5LIB"] to /usr/lib/perl/5.6.0 solved the problem.

It changes more often than DebianStable (DebianEtch), but not as crazily as DebianUnstable (["DebianSid"]). See also DebianStability.

Testing has the worst security update speed compared to stable and unstable. Don't prefer testing if security is a concern. (is this still valid after 2005-06-06?)

DebianLenny is the current testing distro. If you were tracking DebianTesting but really meant to be tracking DebianEtch, update your /etc/apt/sources.list replacing 'testing' with 'etch'. The 'etch' alias would have tracked 'etch' through it's transition into 'stable'. You can do the same for DebianLenny.

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

 ftp://ftp.us.debian.org/debian/dists/testing/Release

If you wonder why a package (or a particular version thereof) is not yet in testing, see http://bjorn.haxx.se/debian.

See also: