in reply to Rot13 Challenge
As you might expect, this has been golfed a few times before. For example:
The Qwika Perl wikipedia example program (which matches Anony's response above) is:while the shortest Perl solution at shinh's golf site is:perl -pe 'tr/A-Za-z/N-ZA-Mn-za-m/' < input_file > output_file
#!perl -p y/N-ZA-z/A-za-m/
In Section
Seekers of Perl Wisdom