I'm new to system administration and I'm helping admin a server for a student group. I was wondering, what is the best practice for when you're upgrading packages and a config file has changes. I've been looking at the differences and then usually just leaving the old version unless it looks like there is something important to add, and otherwise merging the config files manually with kdiff3, but is there a better way to do it?
Also, do I have to backup the old file somewhere myself or does dpkg automatically make a backup? I sometimes I noticed .old files in some directories for old versions of config files.
This issue is complicated by the fact that since I'm new to this group, I don't know why some changes are the way they are, but if in doubt I've been deferring to the existing version.
By the way, I'd like some specificity. Eg, when dpkg prompts you with the whole Y/N/I/O/D/etc thing, what do you do? Do you back up the old file, install the new one, and then merge, or is there a better way to merge the files when you're in that ncurses prompt thing?