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 | 
Return to parent directory.