If you work with Gentoo, you're probably aware of tools like etc-update and dispatch-conf. If you use dispatch-conf, you might know that it supports rcs for version control of the changes it makes. But if you have enabled it, you might be wondering how to actually restore configuration files with it.
Well, dispatch-conf stores its version control information in
/etc/config-archive. To restore a configuration file to a previous
version, first find out what versions there are in the version control
~$ rlog -zLT /etc/config-archive/etc/protocols,v ...
The output of the rlog command should allow you to find the revision you are interested in. The -zLT option displays date/time in the current timezone (instead of UTC). Once you have found the revision you are looking for, restore the file by redirecting the output of the co command:
~$ co -p -r1.1.1 /etc/config-archive/etc/protocols,v > /etc/protocols