RFC: /var/cache/<pkg> should be deleted upon package removal

[Ralf Corsepius]

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

[Ville Skyttä]

On Tuesday 09 February 2010, Ralf Corsepius wrote:
> 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.

vdr-osdteletext does, but that's a drop in the ocean.
> This leads to /var/cache/ gradually filling up with
> orphaned/unused files, e.g. when temporarily installing mock or abrt.
>
> Thoughts?

FWIW, no objections to mandating removal of that stuff here.