This page covers:
     Where is the Config File
     Using the phpinfo() Function

Where is the Config File?

The config file is called php3.ini (in version 4.0, it's simply called php.ini). On the Windows platform, this file should be in the windows directory (usually C://Windows). If you're on a *NIX platform, it'll probably be in /usr/local/lib or /etc/httpd (LINUX). But this can vary depending on your own configuration parameters during installation and whether or not you used the RPM (Redhat Package Manager) or manually config/make/installed PHP. I've found that on my LINUX box, by default, the RPM placed the php3.ini file in /etc/httpd and when installing manually, it was configured to be at /usr/local/lib though it didn't actually put the php3.ini file in the directory.

Using the phpinfo() Function

If you're unsure where you're php3.ini (or php.ini) file is located, you can use the phpinfo() function to see all the settings of your PHP configuration including the config file directory. Create a new file called info.php and add the following code: <? phpinfo(); ?>.