virtual server with fcgi and php using shell_exec with max_execution_time

Hello,

i have create a virtual server with the use of fcgi-php5 which works fine. i have a script that runs admin tasks and i call it through a web interface. the issue at start was that after 30 seconds it just stop, after updating the php.ini to that virtual server that did'nt help at last i found the max execution time in the Website Options. that works if a script runs within its own enviroment for how long that i want. the issue start when i use the PHP shell_exec() command , it just doesnt work and close the script and returning 500 internal error.

i search the forums and various places and i found out that i might need to update pgp5.fcgi file config to have PHP_FCGI_CHILDREN larger then 2 so the script i am runnig from a web could go to shell and run another script. i change that with that post that says how to make the file mutable (chatter linux cmd) i changed it to equal 5 - PHP_FCGI_CHILDREN=5 , but it didn't work.

any ideas on this? also because of this i get from apache this error: "End of script output before headers: script.php" i guess its because when it gets to shell_exec() command it just force it to be finished with no warning causing 500 internal server error.

Thank you. P.S using ubunto 12 on digital ocean