rot13

#!/bin/sh
#
# NAME
#
#   rot13 - rot13 cipher
#
# SYNOPSIS
#
#   rot13 [<file>...]
#
# DESCRIPTION
#
#   This script exists mainly because tr(1) doesn't
#   accept files as arguments.
#
# EXAMPLE
#
#   $ rot13 /usr/share/dict/words | rot13
#

if [ "$*" ]
then
    # Not a useless use of cat!
    cat "$@" | tr "A-Za-z" "N-ZA-Mn-za-m"
else
    tr "A-Za-z" "N-ZA-Mn-za-m"
fi