Below are the exact steps to enable a particular PHP function:
1. Remove all functions from disable_functions in php.ini
2. Add functions in php.ini suhosin.executor.func.blacklist = “” those you want to disable globally.
After that in the virtual host section of a domain you can add below code to enable a function only for one domain:
php_admin_value suhosin.executor.func.blacklist = “shell_exec”
In this example shell_exec has been enabled for the VirtualHost.