Unmounted Disk Labels

You have a server with a dozen or so disks, and you want to know which labeled volumes are sitting idle without mounting each one individually. The command below walks through every symlink in /dev/disk/by-label/, resolves it to the underlying block device, checks /proc/mounts, and prints only the labels that are not currently in use.

The Command

for DISKLABEL in $(find /dev/disk/by-label/ -type l); do
  RES=$(readlink -f "$DISKLABEL")
  grep -q "^$RES" /proc/mounts || echo "$RES (${DISKLABEL#*/})"
done

How It Works

1. Find labeled devices. find /dev/disk/by-label/ -type l returns every symlink in the by-label directory. Each symlink name is the filesystem label you assigned with e2label, xfs_admin -L, or a similar tool.
2. Resolve the real device. readlink -f follows the symlink chain to the actual block device (for example, /dev/sdb1).
3. Check the mount table. grep -q "^$RES" /proc/mounts silently succeeds if the device appears as a mount point. The || ensures the echo only runs when the device is not found.
4. Print the label. ${DISKLABEL#*/} strips the leading /dev/disk/by-label/ path so the output is clean, like /dev/sdb1 (DATA).

Example Output

/dev/sdb1 (DATA)
/dev/sdc1 (BACKUP)

Each line tells you the block device and the human-readable label, making it easy to decide whether to mount, repurpose, or remove the volume.

Tips

• Run the command as a regular user; it only reads /proc/mounts and the /dev/disk symlinks, so no root privileges are needed.
• If you want the opposite list (devices that are mounted), simply remove the || and the grep -q guard, or invert the logic with &&.
• Pair this with lsblk -o NAME,LABEL,MOUNTPOINT for a quick visual cross-check.

• SysAdmin

• Bash
• SysAdmin