Dynamically link /sites/default/css/css_***.css file for WordPress template header
To answer your direct question, drupal's CSS and JS aggregation contains a random MD5 hash to guarantee uniqueness, and also to guarantee that there is no programmatic way to work this out.

In order to include CSS and JS from an aggregated site into another CMS there are a couple of options:


Use un-aggregated CSS and JS and link to the files direct (bad)
Compress the files yourself and host them in a known location - e.g. /css/main-compressed.css
Or another option is what we have used in the past where you basically make a really simple page.tpl.php which includes basically no content, and is for all intensive purposes a blank wrapper for your site. You have your other CMS drag this template down after every deployment, and then used it for it's page wrapper. This way you do not need to worry about the CSS and JS changing as you always have the most up to date versions in the &lt;head&gt; section.


Hope this helps