This is standard behavior with the CGI module. Since you're coding your script with it, I'm assuming you're trying to build a CGI script. For that reason, when you run your script from the command-line, CGI.pm notices this and assumes you are developing/trying to test your CGI script and gives you the means to pass form variables to it. See the CGI documentation. If you'd just like to go ahead and run the script without arguments, send it an EOF (ctrl-D under Unix) to signal the end of your variables.

If you are not trying to write a CGI script, you should remove the 'use CGI' line.