I recently added a line for a USB memory stick to
/etc/fstab, to be able to mount it automatically, using UUID to identify the device.
Before I already have several external ext4 drives that have their UUIDs written in lowercase hexadecimal chars
[0-9a-f] like this:
UUID=3eeaaa43-dead-beef-cafe-243bcaaad475 /media/external_2TB ext4 rw,user,noexec,nosuid,nodev,noatime 0 2
I checked the UUID of my USB stick with
blkid, got an uppercase hexadecimal UUID and entered it in
/etc/fstab in the same way as the ext4 lines, in lowercase hexadecimal, like this:
UUID=125c-a3eb /media/usb_8GB vfat defaults,users,umask=0 0 0 mount: special device UUID=125c-a3eb does not exist
Then I got an idea to try it in uppercase (gU3w in Vim) and it worked without problems. To confirm this, I unmounted, and changed the UUID back to lowercase, mount failed, and back to uppercase, and mounted successfully.
As far as I have understood, UUID is a hexadecimal number, not a string, so the case of letters should be irrelevant. But clearly it's not. RFC4122 defines UUID as "case insensitive on input". Is there something I have missed or is this
umount behavior a bug?
I'm using Debian GNU/Linux 7.0 Wheezy with a custom kernel version 3.6.8, if that matters.