I haven't had need to mess with X for a long time (I'd guess it was still when Xfree86 ruled).A few weeks ago, however, I was trying to get a laptop to use an external display and I managed to cripple the setup (annoying flashing screen).Since the laptop was already due an upgrade (and I had a backup of /home) I just upgraded to F24 and moved on, but it got me thinking that I should probably have a backup of a working configuration.What files should I backup in case I need to mess with X again?Or should I just backup everything in /etc and not worry about specifics?
What to backup before messing with X
fedora;xorg;configuration;backup;etc
Just back up /etc. (And don't put configuration files elsewhere, obviously, e.g. never modify files under /usr.)Rather than rolling your own, install etckeeper, which automatically commits modification in your chosen version control system on package upgrades. When you make changes, commit them (git commit or hg commit or bzr commit or darcs record) with an explicit log message to remember why you did it.