Ed's Software Guide on Linux

Disclaimer: This document is provided "as is" without warranty. Use at your own risk. In no event shall I be liable for any damage resulting from the use of this work.

Does the following scenario sound familiar: after changing the configuration of your Linux system, something breaks and you're not sure what you need to do to fix it?

To recover from such a situation, I recommend that you keep "snapshots", or versions, of your /etc filesystem, and that you take a new snapshot whenever you make a change to the configuration. Remember that you can change configuration by using a config application (e.g. Dialup Configuration), by installing new packages, or of course by editing /etc files manually.

The process is straightforward:

• Create a directory to hold the snapshots. E.g.: mkdir /root/etc-snapshots
• Take an initial snapshot (after finishing the Linux installation) by doing a recursive copy of the /etc filesystem to /root/etc-snapshots. E.g.: cp -R /etc /root/etc-snapshots/1-originalconfig
• After changes are made to /etc file(s), take a new snapshot. E.g.: cp -R /etc /root/etc-snapshots/2-nvidiadriver
• To see changes between different versions of your /etc files, use the recursive functionality of the diff command. E.g., from the /root/etc-snapshots directory: diff -r 1-originalconfig 2-nvidiadriver > diff.log
• If ever you make a config change that screws up your system (e.g. you can't boot), you can restore to a previous snapshot by booting linux in rescue mode and replacing the appropriate files.

Why not use CVS for versioning the /etc files?

Good question! I tried using CVS to maintain the /etc files, but as it turns out, the root account can't use certain CVS commands such as cvs commit. Also, keeping the /etc files in a repository can create a security risk: typically, permissions are relaxed on the directories in the CVS repository, and the last thing you want is for some sensitive /etc files to be visible to CVS users.

I hope you found the content on this page useful (and accurate). Please email me with feedback and corrections.

Copyright © 2002 Ed B. Park