Just log into your server via SSH and run:
php -i |grep php.ini
Alternatively you can create a new php file and use the following:
<? phpinfo();?>
Open this file in your browser and you will be able to find your php.ini
file.
With WHM / cPanel based servers your php.ini
file will be at /usr/local/lib/php.ini
. Your edits to this file will not be overwritten.