[plug] finding out what packages are installed using apt-cache

[David & Lisa Buddrige]

Hi all,

I've just got my first debian system up-and-running, and am coming up to
speed, having mostly used redhat and slackware systems previously.

My hard-drive is fairly chokka at this point, and am subsequently wanting to
see what I can remove to free up some space.  I've already run apt-get clean
to clear out the .deb's that were buffered on the hard-drive, and my next
step was to read the manual page for apt-get and apt-cache.  The apt-cache
command

    apt-cache pkgnames

seemed the most obvious one to list what's on the system, and having run it,
I identified a couple of packages that could probably go.

I then ran

    apt-get remove <packagename>

to remove the package, however apt-cache then informed me that the package
concerned was not installed.  It seems that this is listing *all* packages
(presumablty that were available on the ftp site that I installed from) -
whether they're installed or not.  The only other options that appear in the
manual seem to want you to type in the name of the package that you are
interested in; could someone enlighten me as to how to find out which
packages are *installed*.

thanks heaps in advance guys

David Buddrige