Thanks for that. Maybe I misunderstood your response, but $checkme isn't the tempfile, it's the file with the name of the tempfile written in it. That file is going to exist no matter what. (Isn't it?) And since the checker script doesn't know the name or filehandle of the tempfile, it can't go looking for it, so that's why I create a file whose name it does know, wherein it will find the name of the tempfile, whose existence it can then verify. So -e is checking the existence of $line, which in this case is the name of the tempfile as read from $checkme.

However, MAX_INTEGER sounds intriguing. I'm going to have to look that up... : )