#!/usr/bin/perl
use warnings;
use strict;
use IO::Select;

my $timeout = 1;

my $s = IO::Select->new();
$s->add( \*STDIN );

while (1) {
    if ( my @ready = $s->can_read($timeout) ) {

        # we got input
        for my $fh (@ready) {
               my $input;
               sysread( $fh, $input, 1024);
            	                          
	       #do some processing, for example
	       syswrite(STDOUT, "processed: $input");
        }
    }
}