How to redirect the output of a .php to a file on the webserver?

Hi there.. I use PHP to insert the content of a database into a HTML-file. This is done every time a page is requested. Now, what I would like is, to only do this when the content changes. So, when the content changes, I would like to call the .php that uses that content and redirect its output to a file, instead of a browser. something like "mypage.php > mypage.html" would be perfect.. but how? A second option would be something like fwrite(exec(webpagina.php)); but i guess that wouldn't work with a .php as argument. A third (and nasty) solution would be to fwrite() all html content and fwrite() the database stuff in stead of echo-ing it. Anyone? Thanks. - John van Terheijden, the Netherlands