inside the while (<FILE>){} loop, you would use the normal loop controlling events, namely next and last. In this case you probably want last, you would just use last if $_ = marker or whatever.
Comment on Re: Jumping out of a partially read file
BUU you nailed it! Thanks also to particle for the tip on warning instead of dying on the file open. All the other suggestions were great too! Oh, thelenm, when it jumps out, it jumps to a close(FILE), but thanks for confirming it before I had to ask about it =]. Thanks again everyone for the very helpful responses!