#!/usr/bin/perl use strict; while () { chomp; if ( length() == 9 and not ( /[^0-8]/ or /(.).*\1/ )) { print "$_\n"; } else { warn "rejected input: $_\n"; } } __DATA__ 01234 123456780 1234567890 223456781 345678012 234567890 a12345678 012345678 456782011 456782013