An external disk carries a filesystem whose label is `backup`. Which command mounts it on /mnt/backup by that label, without naming any /dev node?
LPIC-1 Exam 101-500, objective 104. Devices, Linux filesystems, filesystem hierarchy standard easy
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The options
Correct mount -L backup /mnt/backup
Correct. -L (--label) mounts the filesystem carrying that label. The equivalent form in /etc/fstab is LABEL=backup in the first field.
Not correct mount -U backup /mnt/backup
Wrong option letter. -U selects a filesystem by UUID, so it would look for a filesystem whose UUID is the literal string backup and find nothing.
Not correct mount -t backup /mnt/backup
Wrong. -t states the filesystem type, such as ext4, xfs or vfat. There is no type called backup, and the command names no source anyway.
Not correct blkid -L backup /mnt/backup
Wrong tool. `blkid -L backup` prints the device node that carries that label, which is useful for finding it, but blkid never mounts anything.
Why
Labels and UUIDs both identify a filesystem by something stored inside it rather than by the kernel's enumeration order, which is why they survive a new disk controller or a reshuffled cable. On the command line they are -L and -U; in /etc/fstab they are written LABEL= and UUID= in the device field. Labels are set at creation time or afterwards with e2label and tune2fs -L on ext, or xfs_admin -L on XFS, and are readable with blkid or lsblk -f.
Where this comes from
- Cited
- manual page mount(8)
Practise this
Reading one question is not practice. The trainer will draw a short set from objective 104 and space the ones you get wrong.
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