use IO::Select;
use IO::Socket;
use POSIX;

##### setup the file....
# open it
open my $tail, $FILE or die $!;

# set to non-blocking
fcntl( $tail, F_SETFL(), O_NONBLOCK() );

# [ fill up the file info buffer ]

###### setup the socket....                                                                                     
$main_sock;
$readable_handles;
$main_sock = new IO::Socket::INET(
	LocalHost => 'localhost',
	LocalPort => $PORT,
	Listen    => 8,
	Proto     => 'tcp',
	ReuseAddr => 1,
);
$readable_handles = new IO::Select();
$readable_handles->add($main_sock);

while (1) {

	######### do file tail stuff here...                                                                         
	# unset the EOF (as seen in Perl Cookbook)
	$tail->clearerr();

	# read any new lines
	if ( @lines = (<$tail>) ) {

		# [ add @lines to buffer ]
		# [ discard old lines from buffer ]
		# [ other processing of data... ]
	}

	######### do TCP socket stuff....                                                                       
	($new_readable) = IO::Select->select( $readable_handles, undef, undef, $TIMEOUT );
	foreach my $sock (@$new_readable) {
		if ( $sock == $main_sock ) {
			$new_sock = $sock->accept();
			$new_sock->autoflush(1);
			$readable_handles->add($new_sock);
		} else {
			if ( $ret = sysread $sock, $buf, 4 ) {
				# [ process the received info, generate $reply ]
				# reply to the client                                                               
				print $sock $reply;
			}
			# close the client                                                                      
			$readable_handles->remove($sock);
			close $sock;
		}
	}
}