When package managers like APT and RPM install or update a package, they often edit configuration files in /etc and other places. How can I tell which files I can edit and which should be left to the package manager?

For instance, on Debian, I can edit my X config file, but I have to be careful not to run dpkg-configure or all my changes are lost. So what happens if a new version of X.org comes out, which needs to alter the format of xorg.conf?

And I have a SuSE setup on which I have been editing the SSH configuration freely - might I lose my changes if SSH is upgraded to a new version?

Are there any general principles, or is each package different?

Thanks,

Peter.

For RPM packages config files should have "%config(noreplace)" set in the .spec file which means they will save the config as "config.rpmnew" or alike. Unfortunately there is no easy way to check for this when upgrading a package. I keep aproximately ninety percent of configs in a versioning system so it's easy to revert back in case of unwanted changes. A way could be to list the contents of the rpm and backup the config files. You probably don't even need to do that, because you make backups, do you?.. Next to that a lot of packages (lynx, pine, fetchmail etc, etc) first search in the users home for configs before looking in the systemwide config dirs. This way you can easily override systemwide settings. RPM packages don't touch user configs.

I always keep backups of everything I edit. So if the file does get replaced, or I want to revert back to a previous version, it's a simple thing to do. It's just me as root on this system, and no concurrent editing of config files with other users, so I use the simpler RCS rather than CVS.

e.g.,

p.s., the above "mkdir RCS" and "ci -i -u <filename>" are only required for your initial editing. Once you've put the thing under RCS control subsequent edits are simply:

Thanks for the replies! Tracking diffs with source control is a cunning plan - I'll try it.