Chapter 3. Binary packages

15

Since these packages cannot be easily removed (one has to specify an extra force option to

dpkg

to do so), this flag must not be used unless absolutely necessary. A shared library package

must not be tagged

essential

; dependencies will prevent its premature removal, and we

need to be able to remove it when it has been superseded.

Since dpkg will not prevent upgrading of other packages while an

essential

package is in an

unconfigured state, all

essential

packages must supply all of their core functionality even

when unconfigured. If the package cannot satisfy this requirement it must not be tagged as

essential, and any packages depending on this package must instead have explicit dependency

fields as appropriate.

You must not tag any packages

essential

before this has been discussed on the

debian devel

mailing list and a consensus about doing that has been reached.

3.9 Tasks

The Debian install process allows the user to choose from a number of common tasks which a

Debian system can be used to perform. Selecting a task with

tasksel

causes a set of packages

that are useful in performing that task to be installed.

This set of packages is all available packages which have the name of the selected task in the

Task

field of their control file. The format of this field is a list of tasks, separated by commas.

You should not tag any packages as belonging to a task before this has been discussed on the

debian devel mailing list and a consensus about doing that has been reached.

For third parties (and historical reasons), tasksel also supports constructing tasks based on

task packages. These are packages whose names begin with task . Task packages should not be

included in the Debian archive.

3.10 Maintainer Scripts

The package installation scripts should avoid producing output which is unnecessary for the

user to see and should rely on

dpkg

to stave off boredom on the part of a user installing many

packages. This means, amongst other things, using the

  quiet

option on

install info

.

Errors which occur during the execution of an installation script must be checked and the

installation must not continue after an error.

Note that in general `Scripts' on page

80

applies to package maintainer scripts, too.

You should not use

dpkg divert

on a file belonging to another package without consulting

the maintainer of that package first.

All packages which supply an instance of a common command name (or, in general, file 

name) should generally use

update alternatives

, so that they may be installed together.

If

update alternatives

is not used, then each package must use

Conflicts

to ensure