2.2. Package control information files

The control information portion of a binary package is a collection of files with names known to dpkg. It will treat the contents of these files specially - some of them contain information used by dpkg when installing or removing the package; others are scripts which the package maintainer wants dpkg to run.

It is possible to put other files in the package control information file area, but this is not generally a good idea (though they will largely be ignored).

Here is a brief list of the control information files supported by dpkg and a summary of what they’re used for.

control

This is the key description file used by dpkg. It specifies the package’s name and version, gives its description for the user, states its relationships with other packages, and so forth. See Source package control files – debian/control and Binary package control files – DEBIAN/control.

It is usually generated automatically from information in the source package by the dpkg-gencontrol program, and with assistance from dpkg-shlibdeps. See Source packages (from old Packaging Manual).

postinst, preinst, postrm, prerm

These are executable files (usually scripts) which dpkg runs during installation, upgrade and removal of packages. They allow the package to deal with matters which are particular to that package or require more complicated processing than that provided by dpkg. Details of when and how they are called are in Package maintainer scripts and installation procedure.

It is very important to make these scripts idempotent. See Maintainer scripts idempotency.

The maintainer scripts are not guaranteed to run with a controlling terminal and may not be able to interact with the user. See Controlling terminal for maintainer scripts.

conffiles This file contains a list of configuration files which

are to be handled automatically by dpkg (see Configuration file handling (from old Packaging Manual)). Note that not necessarily every configuration file should be listed here.

shlibs

This file contains a list of the shared libraries supplied by the package, with dependency details for each. This is used by dpkg-shlibdeps when it determines what dependencies are required in a package control file. The shlibs file format is described on The shlibs File Format.