To update the local cache from apt repositories
apt-get update
To download and install a package (including dependencies):
apt-get install package-name
To install a single .deb package:
dpkg --install package.deb
To remove a package:
apt-get remove package-name
To find all available packages that match a pattern:apt-cache searches the package names and descriptions.
apt-cache search pattern
To display package information:
apt-cache show package-name
To show all installed packages:
dpkg --list
To show all files that belong to a package:
dpkg --listfile package-name