#!/usr/bin/perl
use Term::ReadKey;
#passing ReadKey() an argument of -1 to indicate not to block: 
ReadMode('cbreak');

while(1){
my $char;
if (defined ($char = ReadKey(0)) ) {
        print "$char->", ord($char),"\n";    # input was waiting and it was $char 
} else {
          # no input was waiting 
        }
}

ReadMode('normal');   # restore normal tty settings