Are apt-file and apt-cache part of apt? [duplicate]
Solution 1:
apt-file is its own separate program that is not part of apt, but has interactions with apt components, more specifically it pulls a list of 'files' known in packages and then searches the data in those lists of files to find certain searched-for terms and parameters. It has apt-like functions but it's its own package in the Universe (non-main, community-contributed and supported) repositories.
apt-cache however is part of the apt packages/suite, and is a 'standard' apt utility/program that is installed with every Ubuntu installation.