Serving Drupal 7 with built-in PHP 5.4 server
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I am looking to develop a Drupal 7 site using PHP's built-in server. I have successfully run Drupal without clean urls (e.g. *index.php?q=/about/*) but clean urls (e.g. */about/*) normally rely on mod_rewrite or its equivalent. In the docs I see you can run the PHP server with a router file like so:

    php -S localhost:8000 routing.php

What should I put in the routing.php to simulate mod_rewrite?