<?php 
/* our simple php ping function */ 
function ping() { 
exec(sprintf('ping -c 1 -W 5 %s', escapeshellarg()), , ); 
return  === 0; 
} 
/* check if the host is up  can also be an ip address */ 
 = 'www.example.com'; 
 = ping(); 
/* optionally display either a red or green image to signify the server status */ 
echo '<img src="'.( ? 'on' : 'off').'.jpg" alt="'.( ? 'up' : 'down').'" />'; 
?>