apt-cache

• Search:
• apt-cache search [package name]
• Show:
• apt-cache show [package name]
• Install Check:
• apt-cache policy [pkg name]
• List Installed:
• apt-cache pkgnames

The apt-cache command can display much of the information stored in APT's internal database. This information is gathered from the different sources listed in the sources.list file during the apt update operation