6.9 What is meant by saying that a package Depends, Recommends, Suggests, Conflicts, Replaces or Provides another package?

The Debian package system has a range of package "dependencies" which are designed to indicate (in a single flag) the level at which Program A can operate independently of the existence of Program B on a given system:

• Package A depends on Package B if B absolutely must be installed in order to run A. In some cases, A depends not only on B, but on a version of B. In this case, the version dependency is usually a lower limit, in the sense that A depends on any version of B more recent than some specified version.

• Package A recommends Package B, if the package maintainer judges that most users would not want A without also having the functionality provided by B.

• Package A suggests Package B if B contains files that are related to (and usually enhance) the functionality of A.

• Package A conflicts with Package B when A will not operate if B is installed on the system. Most often, conflicts are cases where A contains files which are an improvement over those in B. "Conflicts" are often combined with "replaces".

• Package A replaces Package B when files installed by B are removed and (in some cases) over-written by files in A.

• Package A provides Package B when all of the files and functionality of B are incorporated into A. This mechanism provides a way for users with constrained disk space to get only that part of package A which they really need.

More detailed information on the use of each these terms can be found in the Policy manual.