I was only provided a snippet of the real input file; I don't know if I have the actual first two bytes of the file. I'll ask my friend about that.

What *should* happen to the output file is that another perl script is used to sort the lines by date/time for a different view of the data. My friend has looked at it with Notepad, Notepad2 and a hex editor, and he says it comes out of the undupe script padded with \x00 bytes.

My OSX passes the braindead test, so does my WinXP which is supposedly now set up the way his is. I'll send him that test, thanks!

3 copies - because I'm an idiot, and have RAM to burn. :-) That is a very nice way you did it. That should scale up nicely.