List all installed packages:

=>
dpkg-query -l
dpkg --get-selections
apt list --installed
<=

List all packages that are available for install from sources in ``/etc/apt/sources.list``

=>
apt-get update
apt-cache dumpavail
<=

To find out what package contains a file:

=>
dpkg-query -S libf2c.so.2.1
<=


List all files owned by a package

=>
dpkg -L package-name
<=

Reinstall a package

=>
sudo apt-get install --reinstall package-name
<=

What does a package depend on?

=>
apt-cache depends package-name
<=

What depends on this package?

=>
apt-cache rdepends package-name
<=