Chapter 6. Basics of the Debian package management system

29

Currently all of the control files can be found in directory

/var/lib/dpkg/info

. The files

relevant to package

foo

begin with the name  foo  and have file extensions of  preinst ,

 postinst , etc., as appropriate. The file

foo.list

in that directory lists all of the files that

were installed with the package

foo

. (Note that the location of these files is a dpkg internal;

you should not rely on it.)

6.7 What is an Essential Required, Important, Standard, Optional, or

Extra package?

Each Debian package is assigned a priority by the distribution maintainers, as an aid to the

package management system. The priorities are:

  Required: packages that are necessary for the proper functioning of the system.

This includes all tools that are necessary to repair system defects. You must not remove

these packages or your system may become totally broken and you may probably not

even be able to use dpkg to put things back. Systems with only the Required packages

are probably unusable, but they do have enough functionality to allow the sysadmin to

boot and install more software.

  Important packages should be found on any Unix like system.

Other packages which the system will not run well or be usable without will be here. This

does NOT include Emacs or X11 or TeX or any other large applications. These packages

only constitute the bare infrastructure.

  Standard packages are standard on any Linux system, including a reasonably small but

not too limited character mode system.

This is what will install by default if users do not select anything else. It does not include

many large applications, but it does include some development software like the GNU C

and C++ compilers (

gcc

,

g++

), GNU make, as well as the Python interpreter and some

server software like OpenSSH, the BSD printer daemon (

lpr

) and the RPC portmapper

(

portmap

).

  Optional packages include all those that you might reasonably want to install if you did

not know what it was, or do not have specialized requirements.

This includes X11, a full TeX distribution, and lots of applications.

  Extra: packages that either conflict with others with higher priorities, are only likely to

be useful if you already know what they are, or have specialized requirements that make

them unsuitable for  Optional .

If you do a default Debian installation all the packages of priority Standard or higher will be

installed in your system. If you select pre defined tasks you will get lower priority packages

too.