I've tried various ways of removing a package, trying all variations of apt-get remove, --purge, -P and so on. Also trying them with dpkg. I always get the same errors:

Removing serna-3.1 ...
Variable INSTALL_PREFIX is not set!
dpkg: error processing serna-3.1 (--remove):
subprocess post-removal script returned error exit status 1
Errors were encountered while processing:
serna-3.1
E: Sub-process /usr/bin/dpkg returned an error code (1)


I'm tearing my hair out - any ideas?

Are you doing this with a Redhat implementation of Apt?

It's apt-get in a Debian distribution (Kanotix live CD originally). Also, it wants to remove the serna package before I install anything:

apt-get install t1utils
Reading package lists... Done
Building dependency tree... Done
The following packages will be REMOVED:
serna-3.1
etc.

so I'm dead in the water ..

Found another command to try:

apt-get remove --force-yes serna-3.1

but it does the same thing (below). BTW, does
anyone know how to remove something from the database by hand?

# apt-get remove --force-yes serna-3.1
Reading package lists... Done
Building dependency tree... Done
The following packages will be REMOVED:
serna-3.1
0 upgraded, 0 newly installed, 1 to remove and 1004 not upgraded.
1 not fully installed or removed.
Need to get 0B of archives.
After unpacking 94.9MB disk space will be freed.
Do you want to continue [Y/n]? Y
(Reading database ... 111457 files and directories currently installed.)
Removing serna-3.1 ...
Variable INSTALL_PREFIX is not set!
dpkg: error processing serna-3.1 (--remove):
subprocess post-removal script returned error exit status 1
Errors were encountered while processing:
serna-3.1
E: Sub-process /usr/bin/dpkg returned an error code (1)

Did you try dpkg --purge -f serna-3.1?

Obviously, that package never came from a Debian repo, so in order to delete it, you're going to have to reverse the command that originally installed it.

What's the output of:

That command actually doesn't seem to work:

dpkg --purge -f serna-3.1
dpkg: conflicting actions --field and --purge

However to reverse the command that originally installed it I would have to convert a Serna .rpm
to the .deb format and try that with dpkg. Thats
what didn't work originally. Separately Serna is
installed (by install.sh (I am out of my depth!))
and working Ok. I guess the problem is
the original dpkg failure.

If I have the manufactured Serna .deb, how would that help dpkg to remove it? Thanks.