How do I tell the difference between errors from the shell and perl?
(answer contributed by brian d foy) When you run a Perl script, something else is running the script for you, and that something else may output error messages. The script might emit its own warnings and error messages. Most of the time you cannot tell who said what. You probably cannot fix the thing that runs perl, but you can change how perl outputs its warnings by defining a custom warning and die functions. Consider this script, which has an error you may not notice immediately.