There is absolutely no reason I'm declaring all those variables up front, I guess. Still learning how to be strict. ;) I've always thought the (linux) grep was a bit faster then the builtin one in perl. But with this script it probably doesn't matter much.
And you're right. Your last code does look a lot nicer. I just went for the quick and dirty code. One correction on your last code though:

use constant INFOFIELDS => (LOGIN, MACHINE, MON, DAY, TIME);
[download]

MON should be MONTH. Aside from that it works perfectly.

Teabag.

chmod 666 *.* 'cause everyone should have the right to read and write!