Hi,
The FHS describes the purpose of /var/cache as follows [1]:
<cite>
/var/cache : Application cache data
Purpose
/var/cache is intended for cached data from applications. Such data is
locally generated as a result of time-consuming I/O or calculation. The
application must be able to regenerate or restore the data. Unlike
/var/spool, the cached files can be deleted without data loss. The data
must remain valid between invocations of the application and rebooting
the system.
Files located under /var/cache may be expired in an application specific
manner, by the system administrator, or both. The application must
always be able to recover from manual deletion of these files (generally
because of a disk space shortage). No other requirements are made on the
data format of the cache directories.
</cite>
From this, I conclude that it should be "safe by definition" to remove
/var/cache/<dir> directories and/or files below such directories upon
final package removal.
ATM, none of the packages in Fedora using /var/cache/<dir> (e.g. yum,
mock, abrt) does so. This leads to /var/cache/ gradually filling up with
orphaned/unused files, e.g. when temporarily installing mock or abrt.
Thoughts?
Ralf
[1]
http://www.pathname.com/fhs/pub/fhs-2.3.html#VARCACHEAPPLICATIONCACHEDATA