Well, I can’t just leave old MD5 alone can I?
Our most recent use works like this: A script that processes hundreds of files in a loop first does an md5hash on the whole file as a string, and saves the result, and then it does all of it’s processing (which involves a whole lot of regular expression magic) and then at the end, before it writes the string to disk as a file, once again does an md5hash on it again, and if it hasn’t change, it doesn’t bother writing out a new file.
After processing it’s simple to see how effective the script is after each run, and how many files are affected. Amazing, huh?
(This post is brought to you by the letters M and D and the number 5.)
(PS, Perl r001z!)