The Debian GNU/Linux FAQ
Chapter 6 - Basics of the Debian package management system
6.1 What is a Debian package?
Packages generally contain all of the files necessary to implement a set of
related commands or features. There are two types of Debian packages:
Binary packages, which contain executables, configuration files,
man/info pages, copyright information, and other documentation. These packages
are distributed in a Debian-specific archive format (see What is the format of a Debian binary package?, Section
6.2); they are usually distinguished by having a '.deb' file extension.
Binary packages can be unpacked using the Debian utility dpkg;
details are given in its manual page.
Source packages, which consist of a .dsc file describing
the source package (including the names of the following files), a
.orig.tar.gz file that contains the original unmodified source in
gzip-compressed tar format and usually a .diff.gz file that
contains the Debian-specific changes to the original source. The utility
dpkg-source packs and unpacks Debian source archives; details are
provided in its manual page.
Installation of software by the package system uses "dependencies"
which are carefully designed by the package maintainers. These dependencies
are documented in the control file associated with each package.
For example, the package containing the GNU C compiler (
"depends" on the package
binutils which includes the
linker and assembler. If a user attempts to install
having first installed
binutils, the package management system
(dpkg) will send an error message that it also needs
gcc. (However, this facility can be overridden by
the insistent user, see
dpkg(8).) See more in What is meant by saying that a package Depends,
Recommends, Suggests, Conflicts, Replaces
or Provides another package?, Section 6.9 below.
Debian's packaging tools can be used to:
manipulate and manage packages or parts of packages,
aid the user in the break-up of packages that must be transmitted through a
limited-size medium such as floppy disks,
aid developers in the construction of package archives, and
aid users in the installation of packages which reside on a remote FTP site.