exec() and redirect output of program

I found this on PHP.net: http://us.php.net/manual/en/function.exec.php Note: If you start a program using this function and want to leave it running in the background, you have to make sure that the output of that program is redirected to a file or some other output stream or else PHP will hang until the execution of the program ends. This is what I want... I want to execute another PHP script from the CLI, pass it a parameter and let it go to town after the HTTP request closes. Can someone please illustrate how I can make this work? Thx, Brad