dpkg

Introduction

The dpkg program is the workhorse of the Debian packaging system. When

run with root privilege, it installs and removes groups of software files called

packages. For developers, it builds packages. For normal users, dpkg supplies

information on specific packages, the contents of any particular package, or a

list of the installed packages on the system. It does all of these package man 

agement tasks and more. It is used by dselect, another application discussed

in this chapter, to perform the actual installation of packages. Many Perl pro 

grams and scripts make calls to dpkg as part of their operation. A familiarity

with dpkg provides solutions to many general packaging problems. When all

other installation methods fail, dpkg is often capable of resolving the problem.

Dealing with the interdependence of packages is one of the major tasks of

the Debian Package Management System. The dependency checking features

of dpkg are well advanced when compared to other solutions available in the

Linux community. What does this mean? It means that, if you use dpkg

to attempt the installation of a package, and that package depends for its

proper operation on another package that has not yet been installed, dpkg will

complain and fail to install the new package. While this may, at first, seem

to be a problem, it is actually the solution to the problem. It is far more

unsatisfactory to be able to install a package that will not work after it has

been installed. This dependency mechanism protects the system from such

installations. As dpkg provides information on the package dependency that

has not been satisfied, it is a straightforward task to install the dependent

packages. Once the dependencies have been satisfied the package will install

without problems, and run as expected afterwards. On some systems, one

or more of these  dependent  packages might only be supplied by a  local 

version of the software, unknown to the packaging system. There are ways to

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