Terminal commands for package management can be an essential thing if you come across an unexpected error or are just interested in how things work. Here are a few of the more important ones:
apt-cache search --names-only --installed
Followed by a pattern, the above command searches every package in its cache for it (you can leave or add the given options starting with --).
Followed by a package name, this command gives you basic information about it, e.g version number, dependencies...
This command gives basic statistics about your package cache.
Followed by a package name, this command gives you all of the package's dependencies.
This command gives you a list of unmet dependencies.
Gives you a list of your repositories. The file can also be opened with a text editor to be edited.
Shows the contents of the given directory, where your installed ppa are stored in.