@echo off
:: filename: rot47.btm
:: notes by: Eric Pement
::  updated: 2014-12-06 17:25
:: requires: tr

if "%1" eq "/?" .or. "%1" eq "/h" .or. "%1" eq "-?" .or. "%1" eq "--help" goto syntax
if "%1" eq "" goto filter
if not exist %1 (echo Input file [%1] not found. %+ quit)
:: else, we must have one argument here....

:: GNU 'tr' does not support the System V syntax that uses square brackets
:: to enclose ranges. (see additional notes in GNU info page)
tr "!-~" "P-~!-O" < %1
goto end

:filter
tr "!-~" "P-~!-O"
goto end

:syntax
TEXT
ROT47 - simple Caesar cipher with a larger alphabet than ROT13.
ROT13 affects alphabetic characters only. ROT47 affects all 94
printable characters: !"#$%&'()*+,-./:;<=>?@[\]^_`{|}~ and the
62-character set [0-9A-Za-z]. Literal cmd:  tr '!-~' 'P-~!-O'

Usage: rot47 [file]

Samples:
  {cat|type|echo|etc.} filename | rot47   # use as a filter
  rot47 filename                          # use with one argument
  rot47 /?, /h, -?, --help                # brings up this help message

ENDTEXT
:end