I have installed apache and php. I know php works as I have tested a simple php file on apache server. I'm writing a simple webserver which should be able to process php files. So what I want to do is once I get a request for a php file, something like 'exec php test.php' and get the output and pass it to the client. As I'm not much into Ubuntu, I don't know where is the php executable (should be in \bin right?) to do it. But there is no php file inside \bin or \usr\bin. When I run 'which php' it shows nothing. How do I do this?