Here's a command I wrote for DS lib, it goes in as /secure/cmds/admins/diffit.c and responds to the "diffit" and "help diffit" commands.

Steps to use:

1. When an upgrade is available, do a `liveupgrade all`
2. Once it has finished downloading, do a `diffit`. You will be prompted for each file that is being upgraded to [K]eep the current version, or [R]eplace it with the new version.
3. Once finished, see /log/diff.log for errors, and /log/diffkeep.log for files you chose to [K]eep (You will need to upgrade these files manually).

Future features:

• "More" for long diffs