How are you expecting to run this script? Are you expecting to access it on a web server via a browser, or are you running it on the command line?

The problem, I believe, is "install a script on my host's site". As written, this script will work (verified) from the command line (perl scriptname.pl, or perl -T scriptname.pl, or even ./scriptname.pl). If you are trying to run it as a CGI script on a web browser, then you may need to look at using CGI or a similar module to retrieve the parameters, although I do not expect it would work in that mode as you expect.