where is my php installation path

I would recommend creating a new test.php files and inserting this code:

<?php
phpinfo();
?>

Then browse to test.php in a browser. This should give you a lot of information on php.

If you installed via an rpm also try

 rpm -ql php

or

 find / -name php.ini

I'm not sure what you mean by install path, if you're talking about the binary 'which php' will probably work.

If you're referring to something else like the extension install dir and assuming your php was installed with RPMs, do a 'yum install php-devel' to get the php-config command. You can run it with no options to get a listing of everything it knows or you can request only certain info from it, here's some useful ones for your situation:

php-config --php-binary
php-config --extension-dir
php-config --include-dir

Also try running 'php -i' on the command line to get the output of phpinfo.