in reply to Perl's Warn and Die Signals

I'd just like to note that although $SIG{__DIE__} may be given a standard perl function (be it in the form of an anonymous sub or reference to a named sub), it performs 'magic' on it's provided arguments e.g
$SIG{__DIE__} = sub { print "$0: $_\n" for @_ }; die("a", "bunch", "of", "arguments"); __END__ output - -: abunchofarguments at - line 2. abunchofarguments at - line 2.
So even though you are given greater control over the exit of your program, it's still not a good time to be performing complex operations with your die() handler.
For further info about the munging of $SIG{__DIE__}'s arguments see this node or check out pp_sys.c in the perl source.