open_basedir

mornin, i´m new to the list and to php, so please don´t jump to hard on me, when you think the question is dump. okay: is there a possibility to make a server only execute the php scripts in the document root it was called from? I saw something about open_basedir, but am not sure if that is the way. I badly need to protect the server from i.e. includes, that read out or manipulated server config files, like passwd. I have systems run under redhat, if that matters. could anyone please just let me know how and where? I´ll definatelly need the correct syntax, since that’s my main-problem with php. thanks a lot - ulrich