How can I generate ID's so that I can just PHP Include a Facebook App on all pages?

I have this comment system:

<div class="comment">
<fb:comments xid="THISISTHEID" numposts="10" width="734"></fb:comments>
<div id="fb-root"></div>
<script>
window.fbAsyncInit = function() {
FB.init({appId: 'THISISTHEID', status: true, cookie: true,
xfbml: true});
};
(function() {
var e = document.createElement('script'); e.async = true;
e.src = document.location.protocol +
'//connect.facebook.net/en_US/all.js';
document.getElementById('fb-root').appendChild(e);
}());
</script>
</div>

And I'm basically including this on every tutorial page so that people can comment. Obviously, each page is unique and I want a different instance of comments. How can I make the ID's different for each page while using a PHP include? I would rather not go and post this on every page I have as it would take a while, and I'd like to be edit to edit easily in the future

 

set a variable with the id before including the file

$my_id="THIS_IS_YOUR_ID"; 

Code (markup):

then

FB.init({appId: <?php echo $my_id; ?>, status: true, cookie: true,
xfbml: true});

Code (markup):