On Thu, Dec 07, 2006 at 11:13:59AM +1300, Steve Holdoway wrote: > Ah, so you're testing md5sum against itself? Pretty pointless. Silly me > thought you were testing against a delivered md5sum.
No, Volker has already explained the problem case, it sounds like he is providing something like a "verify your copy of this DVD" script. In which case, the originator of the data creates and publishes the md5, and the consumer checks the validity of their copy by grabbing the published checksum, and comparing it to a live calculation from their data. When you're creating the script to do that, you would not expect the data to change between creation and verification; but that's not true for the final case.
