How to redirect error message to a file

How to redirect error message to a file

Answer:

Assume you have some program/script that print to the standard error stream (i.e. stderr)

E.g. error.pl

print STDERR 'error';

You cannot redirect the error message just by basic file redirection, e.g.

perl error.pl > error.txt

Instead, you need to use 2>

perl error.pl 2> error.txt