my $readsocks  = IO::Select->new($new_client);
my $writesocks = IO::Select->new();

while (($readers, $writers) = IO::Select->select($readsocks,$writesocks)) {
   foreach my $sock (@$readers) {
      # Read from a socket...
      # Perhaps add this socket to $writesocks.
   }
   foreach my $sock (@$writers) {
      # Write to a socket.
   }
}

##</code><code>##


#!/usr/bin/perl -w
use strict;

use IO::Socket;
# include the select package
use IO::Select;

# they're counting the number of connections $nconnections_old = 0;
my $port = 1234;
my $max_clients = 0;
my ($nconnections_new, $nconnections_old) = (0,0);

my $new_client = IO::Socket::INET->new(Proto=>"tcp", LocalPort=>$port, Listen=>$max_clients, Reuse=>1);

# create a new selection and add our basic socket for incoming connections
my $readlist  = IO::Select->new($new_client);
my $writelist = IO::Select->new();

while (my ($readers, $writers) = IO::Select->select($readlist,$writelist)) {

        # for every readable socket
        foreach my $client (@$readers) {

                # check if it is the basic socket
                if ($client == $new_client) {

                        # if it is establish new connection
                        my $add = $client->accept;

                        # add new socket to the selection
                        $readlist->add($add);
                        $writelist->add($add);

                        # increase number of connections
                        $nconnections_new++;

                } else {
                        # Else it's an established connection trying
                        # to talk to us, OR a socket shutting down.

                }
        }

        foreach my $client (@$writers) {
                # Print our message to clients we can write to,
                # if we haven't already done so.

                my $hey="Hey, I am the server, how are you?\n";
                syswrite($client, $hey);

                # Remove that client from the list of clients we
                # want to write to, otherwise we spam them with
                # greetings continuously.

                $writelist->remove($client);
        }

        # if number of connections has changed, print it
        if ($nconnections_old != $nconnections_new) {
                print "Already $nconnections_new connection(s)\n";
                $nconnections_old++;
        }
}