Quick take: The blkid command prints the UUID, filesystem type, and label of block devices. sudo blkid lists them all, and sudo blkid /dev/sdX1 shows one — exactly the information you need to write stable /etc/fstab entries.
Introduction
The blkid command (block ID) identifies block devices by reporting their UUID, filesystem type, and label. UUIDs are the stable identifiers you should use in /etc/fstab instead of device names like /dev/sdb1, which can change between boots — so blkid is a key tool when configuring permanent mounts.
Syntax
The basic syntax of the blkid command is:
blkid [OPTIONS] [DEVICE]Common Options and Parameters
The most useful options and parameters for the blkid command:
| Option | Description |
|---|---|
| (default) | List all block devices with UUID, type, and label. |
| DEVICE | Show details for a specific device. |
| -s UUID | Show only the UUID tag. |
| -o value -s UUID | Output just the UUID value (scriptable). |
| -L LABEL | Find the device with a given label. |
| -U UUID | Find the device with a given UUID. |
Practical Examples
Real blkid commands you can run today:
# List all devices with UUIDs and types
sudo blkid
# Show one device
sudo blkid /dev/sdb1
# Print just the UUID (for scripts/fstab)
sudo blkid -s UUID -o value /dev/sdb1
# Find the device for a label
sudo blkid -L data
# Find the device for a UUID
sudo blkid -U 1234-ABCDTips and Best Practices
- Use the UUID from blkid in
/etc/fstabrather than the device name, so mounts stay correct even if disk ordering changes. blkid -s UUID -o value /dev/sdX1prints just the bare UUID, perfect for scripts and copy-paste into fstab.lsblk -fshows similar information in a tree; blkid is better for scripting a single value.
Final Thoughts
blkid reports the UUID, type, and label of block devices — the stable identifiers you need for reliable /etc/fstab entries. Use its scriptable -s UUID -o value form to grab a bare UUID, and reach for it whenever you set up a permanent mount. It complements lsblk, which gives the friendlier tree overview.
FAQ: blkid Command in Linux
How do I find a partition's UUID in Linux?+
Run sudo blkid to list every device with its UUID, type, and label, or sudo blkid /dev/sdX1 for one. Use sudo blkid -s UUID -o value /dev/sdX1 to print just the UUID.
Why use UUIDs instead of device names in fstab?+
Device names like /dev/sdb1 can change when disks are added or reordered, breaking mounts. A UUID is tied to the filesystem itself, so fstab entries using UUIDs stay correct across reboots.
What is the difference between blkid and lsblk?+
blkid focuses on identifiers — UUID, type, and label — and is easy to script for a single value. lsblk shows the whole device tree with sizes and mount points. Use blkid for UUIDs and lsblk for an overview.
How do I get just the UUID for a script?+
Use sudo blkid -s UUID -o value /dev/sdX1, which outputs only the bare UUID with no labels, ready to paste into /etc/fstab or use in a script.
How do I find a device by its label?+
Use sudo blkid -L labelname, which returns the device path for the filesystem with that label.
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