I also want to make sure, I don't do anything wrong accidently.

• If you really are doing a system wide change, you will save yourself a lot of pain by doing a backup of your system before you try such a global change. That way if you clobber a really important file, you can get the original, pre-change, version back.
• Better yet, if all the files that you want to change are under version control, then do the changes in a working copy: check out a clean up-to-date working copy, make the changes, inspect the result, and if you are happy with it, commit the changes.

Best, beth