apt-cache
Debian and Ubuntu package query tool. tldr-pages
On Linux
Linux
Search for a package in your current sources
apt-cache search queryIdentifyShow information about a package
apt-cache show packageIdentifyShow whether a package is installed and up to date
apt-cache policy packageIdentifyShow dependencies for a package
apt-cache depends packageIdentifyShow packages that depend on a particular package
apt-cache rdepends packageIdentify