If you're open to using modules from CPAN, you can check out Control::CLI. For serial port connections, it will use "Win32::SerialPort or Device::SerialPort for Serial port access respectively on Windows and Unix systems". That let's you write one code that can be used on either platform. And the module's author does include license and copyright information in the documentation.

And there's a chance that you might get better support (like bug fixes) by using the CPAN module than using bikeNomad's code posted on this site.

Just tossing out an alternative for you to consider.