I'm having issues with executing a Shell script via PHP on the server. What it executes is a shell script that runs a java program. The program runs just fine under the user account that PHPsuExec is trying to execute this on . relevant details are : System has 22GB of ram 12GB is free in caches. 15GB is free. LSWS : 4.2.2 PHP : 5.3.x PHP Memory Limit : 999M Application Memory Limit in the lsphp external app : 900mb in soft limit / 2200mb in hard limit I am really not understanding why the shell script is unable to execute and giving errors about not having enough ram.