A google search for "perl signal handler exit" gave this SOPM node, and the first answer also says use END{}.

Of course, going to the next level, you can't switch "exit" handlers midstream, and you can't unregister END{} blocks, AFAIK. I suppose there would have to be only one END{} block, with a dynamic call table for subs, and the call table gets changed as needed during the program execution. (Maybe this is proper class material, with methods to mangle the call table.)

http://www.perlmonks.org/?node_id=849549