Passing userid from Moodle to an external URL

I am looking to include URLs in each Moodle course that points to an external site. I'd like to pass the userid and course ID as GET parameters in the URL to the other site. Are there macros or variables in moodle that will be replace with userid or courseid ? An example - I want to include a URL like http://www.example.com/cgi-bin/index.cgi?userid=<user>&courseid=<course> I am hoping that there is a way to have courseid and user in the URL above be automatically populated by moodle correctly.