I'm following this: http://www.ubuntu.com/download/desktop/create-a-usb-stick-on-ubuntu
and I know a lot of boot-disk creation stuff will wipe my USB---it's 30GB which is more than I can comfortably back up to my HD right now, but I would like to install ubuntu on a friend's machine.
These instructions say: "If you’re not yet sure about installing Ubuntu, you can try it out without affecting your current system." So, that suggests there won't be any deleting, but I'm hesitant to push the "Make startup disk" button here:
...when there's a button so nearby called "Erase Disk" so close by---I would never want erasing my disk to be an option if it weren't necessary. Can someone confirm for me for sure whether this operation will delete my USB contents?