how to make sure a PHP script is loaded one time
<p>I have a cronjob system with PHP. I have a file named cron.php and wanna to check if it is not loaded, load it. it is very important to me that this file run only one time and I need the way how define it is already running. I can't use any system functions like exec,system,... do you have any solutions?</p>

<p><strong>NOTE:</strong> I run my script trough CURL and include_one and require_once don't work for this case.</p>
