In Linux systems, UUIDs (Universally Unique Identifiers) provide a more reliable way to identify storage devices than traditional device names like /dev/sda1. Unlike labels which can be changed and device names which may shift during boot, UUIDs remain constant throughout the filesystem's lifetime.

The most straightforward command to display UUIDs is:

blkid

This will output all block devices with their filesystem types, UUIDs, and other attributes. For example:

/dev/sda1: UUID="5e3a1a7b-01" TYPE="ext4"
/dev/sdb2: UUID="a1b2c3d4-5678" TYPE="xfs"

To get the UUID of a particular mounted filesystem:

lsblk -f /dev/sdXn

Or more specifically:

sudo blkid /dev/sdXn

Replace sdXn with your actual device (e.g., sda1).

For systems using systemd, you can use:

systemd-mount --list

Or examine /etc/fstab entries:

grep UUID /etc/fstab

When writing scripts, you might want to extract just the UUID value:

sudo blkid -s UUID -o value /dev/sdXn

Or for all devices:

lsblk -o NAME,UUID

If you're not seeing expected UUIDs:

• Ensure the device isn't currently mounted read-only
• Check for filesystem corruption with fsck
• Verify the device exists with lsblk

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In Linux systems like Ubuntu, every filesystem is assigned a Universally Unique Identifier (UUID). Unlike partition labels which can be changed, UUIDs are persistent identifiers that remain constant even if the device name changes (e.g., from /dev/sda1 to /dev/sdb1 after hardware changes). This makes UUIDs particularly useful for:

• Stable mounting in /etc/fstab
• Systemd mount units
• Disk management scripts

The most reliable method is using the blkid command, which shows UUIDs for all block devices:

sudo blkid

Sample output:

/dev/sda1: UUID="5e3a1a7b-1a2b-4c3d-8e9f-0a1b2c3d4e5f" TYPE="ext4"
/dev/sdb2: UUID="a1b2-c3d4" TYPE="vfat"

To find just the UUID of a specific partition:

sudo blkid -s UUID -o value /dev/sda1

This returns only the UUID string, perfect for scripting:

5e3a1a7b-1a2b-4c3d-8e9f-0a1b2c3d4e5f

For systems without blkid, try these approaches:

# Using lsblk
lsblk -o NAME,UUID

# From /dev/disk/by-uuid
ls -l /dev/disk/by-uuid/

# Using udevadm (for advanced users)
udevadm info -q all -n /dev/sda1 | grep ID_FS_UUID

Here's how to properly use UUIDs in your /etc/fstab:

# Get UUID
UUID=$(sudo blkid -s UUID -o value /dev/sda1)

# Create backup
sudo cp /etc/fstab /etc/fstab.bak

# Append new entry
echo "UUID=${UUID} /mnt/data ext4 defaults 0 2" | sudo tee -a /etc/fstab

If you encounter problems:

• Verify UUIDs match between blkid and /etc/fstab
• Check for hidden characters when copying UUIDs
• Remember that some filesystems (like FAT) use shorter UUID formats

To change a filesystem UUID (use with caution!):

# For ext2/3/4
sudo tune2fs -U random /dev/sda1

# For XFS
sudo xfs_admin -U generate /dev/sda1

# For FAT/VFAT
sudo fatlabel -i /dev/sda1