I want to put a bootable image of Ubuntu on my USB device. I'm following the directions on ubuntu.com. My USB device has 500Gb or something. Does it have to use all of the space? Or is there a way to only use 2 or 3Gb?
NO, it uses as much as it has to in order to make the device bootable but you can tell it to use more space so that you can store files on the desktop of the live session.