I have wrote an Ubuntu ISO image to an USB pen-drive.
I think Ubuntu is loaded in RAM, and nothing is wrote on my USB. I need to be 100% sure that nothing is wrote onto the USB pen-drive. I am asking you, is it?
If some files are wrote onto the USB pendrive and then deleted from the OS it would be a problem for me.
Best Answer
Nothing will be stored persistently on the drive.
Any modification to any file / folder performed during the usage of the system will be stored in the filesystem loaded into the memory, and not in the filesystem stored into the drive.
If you want proofs, here's a comparison of the MD5 sums of the Ubuntu Desktop 15.04 64 bit ISO and of the USB drive to which I wrote it and from which I've been regularily booting for weeks: