Hi there @uyoobong,

This is not really DigitalOcean specific, you probably have the shell_exec, exec and etc. functions disabled in your php.ini file.

What you could do is create a PHP info file and check if this is the case:

<?php

phpinfo();

?>

Then visit the file via your browser and look for disable_functions. If this is the case edit your php.ini file and remove the shell_exec functions from the disabled_functions list and then restart your Apache service.

Hope that this helps!
Regards,
Bobby