Wordpress Nginx config PHP code question

If you set up a wordpress blog on a LEMP, you have the following snippet in the configuration for the virtual host:

    location / {
        try_files $uri $uri/ /index.php?$args;
    }

I believe I understand how it works. When you surf to http://www.mywordpressblog.com/cat/this-is-a-post.

It first tries to find cat/this-is-a-post in the documentroot. If not found, it tries cat/this-is-a-post/

If this doesn't work it passes some arguments $args to the index.php file.

Question: How do I access the value(s) in $args from within the php code in index.php?

The thing is I want to get hold of the "/cat/this-is-a-post" string, which I can via $SERVER["REQUESTURI"], but I want to know what is in $args as well.

pannix