If an URL of the form
is requested, the server will execute the script
If either is missing, it will not be passed. (httpd convention.)
Note that scripts should normally print "Content-type: text/html\n\n" at the beginning (or whatever the type should be, e.g., "image/gif"). In any case, this package will pick up the type and print it in the MIME header, if needed.
Scripts should not normally exit with non-zero status. If they do, a server error will be logged. (This will happen if the script contains errors.)
See the htbin demo for an example.