#!/bin/sh
# rot13 - trivial cipher rotating by 13 places, see https://en.wikipedia.org/wiki/ROT13
# Copyright (c) 1996-2022 by Ian Kluft
# Redistribution permitted by the author under the conditions of the
# GNU General Public License Version 3.
#    https://opensource.org/licenses/GPL-3.0
#
# ROT13 is symmetrically both encryption and decryption since 13 places is half of the 26-letter the Latin alphabet.
# This program can also be symlinked by the names rotmp and unrotmp for an alternative which is asymmetric.

case $(basename $0) in
    rot13|ROT13) tr '[a-zA-Z]' '[n-za-mN-ZA-M]' ;;
    unrotmp) tr '[f-za-eF-ZA-E]' '[a-zA-Z]' ;;
    rotmp) tr '[a-zA-Z]' '[f-za-eF-ZA-E]' ;;
    *) echo "$0: unrecognized name"; exit 1 ;;
esac