Debian package management tools

Tool	Description	Notes
apt	From the man page: apt provides a high-level commandline interface for the package management system. It is intended as an end user interface and enables some options better suited for interactive usage by default compared to more specialized APT tools like apt-get(8) and apt-cache(8)
apt-get	From the man page: apt-get is the command-line tool for handling packages, and may be considered the user's "back-end" to other tools using the APT library	Invoked via cfengine promises to install new packages
apt-cache	From the man page: apt-cache performs a variety of operations on APT's package cache. apt-cache does not manipulate the state of the system but does provide operations to search and generate interesting output from the package metadata
apt-file	From the man page: apt-file is a command line tool for searching [for] files in packages for the APT package management system
dpkg	From the man page: dpkg is a tool to install, build, remove and manage Debian packages