When I connect a printer how can I make it the default printer automatically? -

I have a USB printer. I have to install it for 2 of my USB ports so each time I connect to a different port I have to set it as the default printer. I want it to automatically do that.

The user usually has a gt; default printer if there is no printer name sent along with the lpr command. So where is the problem is there no way to make it default

Disable the others.