Is there a way to output debug messages in Perl that are not piped?

Question

Is there a way to output debug messages in Perl that are not piped? I have a Perl script that I use in a pipe but I really want to print some diagnostic information to the screen instead of to the pipe.

Answer 1

Are you piping both stdout and stderr? If not, write to the one you're not piping :)

e.g.

print STDERR "This goes to standard error";
print STDOUT "This goes to standard output";

(If you don't provide a handle, STDOUT is the default of course - unless you've asked Perl to use a different default handle...)

Answer 2

Unless you have said something like 2>&1 on the commandline, STDERR should show up on the screen. You can write to STDERR like Jon Skeet suggests or you can use the warn function.