Thanks for the tips. I must admit, I hadn't appreciated the overhead involved with the repeated open/close operations. Turns out seek is my new best friend :-)

The reason the STDIN/STDOUT unix filter paradigm wasn't implemented in this script has more to do with its original development than with with its final functionality. The first script was written on a Mac and I haven't found a good way to deal with STDOUT using MacPerl. Although it did make for some easily-implemented dialogue boxes :-)