Re: safe to purge older versions of installed software?

[Jörg-Volker Peetz <jvpeetz@web.de>]

Robert P. J. Day wrote:
>   this should be an easy one:  on my current (etch) system, there are
> a number of packages that have more than one version installed.  for
> example (and from memory), there are at least three versions of gcc
> installed.  am i safe to remove/purge the older ones?
> 
>   perhaps a better question is, what is the command to list the
> packages that depend on a certain package?  in fedora, i'm used to
> running:
> 
>   $ rpm -q --whatrequires <package>
> 

aptitude comes in handy here:

aptitude search '~i~D^<package>$'

Since aptitude uses regular expressions search <package> is enclosed by ^ and $
to distinguish, e.g., between gcc-4.3 and gcc-4.3-doc.

Also interesting may be

aptitude search '~i!~M(~R~i|~Rrecommends:~i)'

It will show any installed packages that aren't auto which are
dependencies or recommendations of other packages. In short, packages
that aren't marked auto but could (should?) be. Be aware though
that circular depends/recommends prevents all packages in that list to
be marked auto.
-- 
Regards,
Jörg-Volker.