apt-get is the package management utility behind Debian-based Linux systems Ubuntu, Mint and Mepis. A complete list of distributions based on Debian can be found on Distrowatch. Basic Package Management: apt-get update Used to resynchronize the package index files from their sources. The indexes of available packages are fetched from the location(s) specified in /etc/apt/sources.list. For example, when using a Debian archive, this command retrieves and scans the Packages.gz files, so that information about new and updated packages is available.