The module which you should have a look at is Algorithm::Diff originally written by Dominus, now maintained by bikeNomad. Included with this module are the example programs diff.pl and cdiff.pl, the latter of which produces a differential output suitable for use with patch.

Also have a look at the homepage for this module here.

 

perl -e 's&&rob@cowsnet.com.au&&&split/[@.]/&&s&.com.&_&&&print'