Just recently I discovered a problem caused by a trial software install. Files in /usr had been changed to be owned by someone other than root. (postgres).

I did try to fix the problem by running chmod root:root /usr -R

But I'm not confident that everything is now correctly owned.

Because it's an RPM packaged system I can use rpm to help with resetting ownership (--setugids) and permissions (--setperms) as follows:

rpm -qa | xargs -IFILE rpm --setugids --setperms FILE

The command basically says query the rpm database (-q) for all installed packages (-a) pipe the list of packages to xargs and run rpm with the --setugids and --setperms flags set on each package to fix up it's perms.

If you run the above you will see alot of "No such file or directory" messages.

Note: Do the above at your own risk.