Get packaging error you have run into

dpkg -i --force-overwrite /var/cache/apt/archives/<mypackage>.deb  


Reconfigure

dpkg --configure -a


Purge a package

apt-get remove <mypackage> -f --purge
 

which package supplies the file?

dpkg --search /path/to/file/myfile
grep myfile /var/lib/dpkg/info/*.list


extract a .deb:

dpkg-deb -x  <pkg.deb>   <extractInNewDir>


list files installed by .deb:

dpkg-deb -c <pkg.deb>


list files in .deb archive format:

ar tv <pkg.deb>


extract archive from .deb:

ar x <pkg.deb>


Show package info:

dpkg-deb -I <pkg.deb>


Package can't install because of overwrite file from other package:

cd /var/cache/apt/archives
dpkg --force-overwrite -i koffice-data-kde4_1%3a1.9.98.2-0ubuntu3~intrepid2_all.deb
apt-get install -f


Show versions available:

apt-cache policy <packageName>


Install specific version:

apt-get install <packageName> <packageNumber>