Is it possible to create bootable live USB stick with Ubuntu that does not allow writing anything to it, similar to live CD?
By default, while creating live usb if you don't allocate any
It may looks like the above statement is not true if you try to download / install any software or other things. Those are downloaded and also accessible. But that is only for current session. Once you reboot the system all changes will be gone. The live cd/dvd also does the same.