How to debug CGI scripts with simulated variables from server?

[Sean Berry]

I want to debug a script that has a line like the following:
if len(os.environ["QUERY_STRING"]) > 0:

How do I debug this from the command line.  I tried
QUERY_STRING='sized=72&shaped=3' ./aqua_getShapes

But that returns:
QUERY_STRING=sized=72&shaped=3: Command not found.

Please help.  Thanks