#!/usr/bin/ruby -w
# Classical rot13 filter.
#
# File is named "caesar" for Caesar cipher to avoid prefix conflict with
# the rotate scripts.

ARGF.each_char{|c|
   if (c >= "A" && c <= "Z") || (c >= "a" && c <= "z")
      print (((c.ord & 0x1f) - 1 + 13) % 26 +
             (c.ord & ~0x1f) + 1).chr
   else
      print c
   end
}