Package management system

A Package Management System is a collection of tools to automate the process of installing, upgrading, configuring, and removing software from a computer. The term is most commonly used with regards to UNIX-like systems, particularly Linux, as these systems rely far more heavily on it with thousands of discrete packages on a typical installation not uncommon.

In such a system, software is distributed in packages, usually encapsulated into a single file. The file, as well as the software itself, contains information that describes (in machine-readable format) the package's details, including its name, checksums, and the details of any other packages that it either requires the installation of to work, or cannot work with. It may also include information on how to configure the package for use, and how to remove the package cleanly when it is no longer required.

The package manager then uses this information to install, configure, and remove packages as requested by the user.

Some well-known examples of package management systems include:

• RPM, Redhat's package manager, used not only by Redhat by by several other Linux distributions.
• dpkg/apt (used by Debian GNU/Linux).
• The "ports tree" system used by FreeBSD, NetBSD, OpenBSD and the like.
• Portage, used by Gentoo Linux and inspired by the BSD ports system.

Recent versions of Microsoft Windows contain similar facilities.