% perl5.6.1 -w test.pl
Use of uninitialized value in substr at test.pl line 14.
Attempt to free unreferenced scalar at test.pl line 13.
Use of uninitialized value in substr at test.pl line 14.
Attempt to free unreferenced scalar at test.pl line 13.

# other invocations....
% perl5.00503 -w test.pl
[nothing]

% perl5.00503 test.pl
[nothing]

% perl5.6.1 test.pl
Segmentation fault (core dumped)