Chapter 10. Files

82

The distinction between these two is important; they are not interchangeable concepts. Almost

all

conffile

s are configuration files, but many configuration files are not

conffiles

.

Note that a script that embeds configuration information (such as most of the files in

/etc

/default

and

/etc/cron.{daily,weekly,monthly}

) is de facto a configuration file and

should be treated as such.

10.7.2 Location

Any configuration files created or used by your package must reside in

/etc

. If there are

several, consider creating a subdirectory of

/etc

named after your package.

If your package creates or uses configuration files outside of

/etc

, and it is not feasible to

modify the package to use

/etc

directly, put the files in

/etc

and create symbolic links to

those files from the location that the package requires.

10.7.3 Behavior

Configuration file handling must conform to the following behavior:

  local changes must be preserved during a package upgrade, and

  configuration files must be preserved when the package is removed, and only deleted

when the package is purged.

The easy way to achieve this behavior is to make the configuration file a

conffile

. This

is appropriate only if it is possible to distribute a default version that will work for most in 

stallations, although some system administrators may choose to modify it. This implies that

the default version will be part of the package distribution, and must not be modified by the

maintainer scripts during installation (or at any other time).

In order to ensure that local changes are preserved correctly, no package may contain or make

hard links to conffiles.

6

The other way to do it is via the maintainer scripts. In this case, the configuration file must

not be listed as a

conffile

and must not be part of the package distribution. If the existence

of a file is required for the package to be sensibly configured it is the responsibility of the

package maintainer to provide maintainer scripts which correctly create, update and maintain

the file and remove it on purge. (See `Package maintainer scripts and installation procedure' on

page

39

for more information.) These scripts must be idempotent (i.e., must work correctly if

dpkg

needs to re run them due to errors during installation or removal), must cope with all the

variety of ways

dpkg

can call maintainer scripts, must not overwrite or otherwise mangle the

user's configuration without asking, must not ask unnecessary questions (particularly during

upgrades), and otherwise be good citizens.

6

Rationale: There are two problems with hard links. The first is that some editors break the link while editing

one of the files, so that the two files may unwittingly become unlinked and different. The second is that

dpkg

might

break the hard link while upgrading

conffile

s.