http://www.cs.tu-berlin.de/cgi/myprog/some-string-here.The executed program is still ``myprog'' in the CGI directory; but it now gets passed
"some-string-here"in the Unix environment variable PATH_INFO.
There are lots of other environment variables with information about the host the page is accessed from, the library the browser uses, and ``fields'' (e.g. from a fill-out form) that follow the PATH_INFO part, introduced by a question mark. Like for many other programmers, my first CGI program was one that printed out all the information it could possibly figure out; try invoking it and see what I know about you.