Login into you server with the root login details and run following command
[root@server]# /usr/local/cpanel/bin/rebuild_phpconf –current
If server is Suexec then result would look like
DEFAULT PHP: 5
PHP4 SAPI: suphp
PHP5 SAPI: suphp
If you are not sure about Shell then you can also check the SuExec is enabled or not from your WHM. Login into your WHM and in the menu find Configure PHP and SuExec
Check the drop down box for “PHP 4/5 Handler” – and if beside that it says “suPHP” – then the sever is SuExec enabled.
If you dont have server root login details or WHM access, then you can create a php file under your account from cPanel >> File Manager and change the permissions on that file to 777 and open it in a browser. If it gives 500 Internal Server Error, then most probably running suPHP.
As well as you can also create the phpinfo page under your account from your cPanel >> File manager For ex. phpinfo.php with the following code
After creating phpinfo.php page browse it http://yourdomainname.com/phpinfo.php and if it shows Server API = Apache then server is not running PHP in Suexec mode and if Server API = CGI the server is running PHP in Suexec mode.