Is there a way to find out which package was responsible for a DependecyPackageInstallation?

Question

Is there a way to find out from which package installation a certain package was installed as dependency?

Answer 1

In a Terminal, try aptitude why $package.

Answer 2

You could check /var/log/apt/history.log for a log entry.

Also, there are several ways to check for reverse dependencies:

apt-cache rdepends packagename

Will show you all packages that depend on packagename. Also those that are not installed, though. Better would be:

aptitude why packagename

This might require you to install aptitude

if everything else fails, try to remove the package in question and look at which other packages would be removed because of your decision. Remember to answer "n" to the "are you sure?" question.