Recently I ran into major problems using GNU diff. It would crash with "diff: memory exhausted" after only a few minutes trying to process the differences between a couple 4.5GB files. Even a beefy box with 9GB of RAM would run out of it in minutes.
There is a different solution, however, that is not dependent on file sizes. Enter rdiff – rsync's backbone. You can read about it here: http://en.wikipedia.org/wiki/Rsync (search for rdiff).
The upsides of rdiff are:
- with the same 4.5GB files, rdiff only ate about 66MB of RAM and scaled very well. It never crashed to date.
- it is also MUCH faster than diff.
- rdiff itself combines both diff and patch capabilities, so you can create deltas and apply them using the same