Where is php installed on linux

Hi there, I want to install Turck MMCasche. The install instructions say that the path to the php install has to be declared. Now I was searching the linux system for the php install but could not find it! It is compiled as a module and there is a file /usr/local/bin/php but no directory. The instructions read: Step 1. Compiling Turck MMCache export PHP_PREFIX="/usr" $PHP_PREFIX/bin/phpize ./configure --enable-mmcache=shared --with-php-config=$PHP_PREFIX/bin/php-config make You must specify the real prefix where PHP is installed in the "export" command. It may be "/usr" "/usr/local", or something else. Can anybody point me into the right [dir]ections? Thank you in advance, Merlin