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Appendix E

Configuration file handling (from old

Packaging Manual)

dpkg

can do a certain amount of automatic handling of package configuration files.

Whether this mechanism is appropriate depends on a number of factors, but basically there

are two approaches to any particular configuration file.

The easy method is to ship a best effort configuration in the package, and use

dpkg

's conffile

mechanism to handle updates. If the user is unlikely to want to edit the file, but you need them

to be able to without losing their changes, and a new package with a changed version of the

file is only released infrequently, this is a good approach.

The hard method is to build the configuration file from scratch in the

postinst

script, and

to take the responsibility for fixing any mistakes made in earlier versions of the package auto 

matically. This will be appropriate if the file is likely to need to be different on each system.

E.1 Automatic handling of configuration files by

dpkg

A package may contain a control area file called

conffiles

. This file should be a list of

filenames of configuration files needing automatic handling, separated by newlines. The file 

names should be absolute pathnames, and the files referred to should actually exist in the

package.

When a package is upgraded

dpkg

will process the configuration files during the configuration

stage, shortly before it runs the package's

postinst

script,

For each file it checks to see whether the version of the file included in the package is the same

as the one that was included in the last version of the package (the one that is being upgraded

from); it also compares the version currently installed on the system with the one shipped with

the last version.

If neither the user nor the package maintainer has changed the file, it is left alone. If one or the

other has changed their version, then the changed version is preferred   i.e., if the user edits