I was preparing a USB thumb drive for installing Debian 8.3. Per the installation instructions, it suggests:cp debian.iso /dev/sdX     # e.g. /dev/sdb, no /dev/sdb1syncSo I gave this a try. I noticed after doing this that if I try to mount /dev/sdb1, it does mount, however it always mounts as read-only, regardless of whatever options I pass. I tried with a few USB drives, with the same result.Why will the drive only mount as read-only after doing the above? Is there a way to still mount it as rw?
Why does a USB drive only mount as read-only after copying a disk image to it?
mount
You'll likely notice that the filesystem as shown in mount is not EXT3 or FAT, it's ISO 9660.  The process of making the filesystem for the disc is write-once, so when the disc image or disc is mastered, it can't be changed after that point.  The only thing you can do is copy the data to another filesystem type that is read-write (e.g. EXT3).  Given most people just use the ISO to install the OS and then ditch it after that, you might want to submit a separate question for why you want to modify the disc image.