How do I find the UUID of a filesystem

Question

I'm running Ubuntu, and want to find out the UUID of a particular filesystem (not partition). I know I can use e2label /dev/sda1 to find out the filesystem label, but there doesn't seem to be a similar way to find the UUID.

Answer 1

Another command that might be available and also works quite well for this is 'blkid'. It's part of the e2fsprogs package. Examples of it's usage:

Look up data on /dev/sda1:

topher@crucible:~$ sudo blkid /dev/sda1
/dev/sda1: UUID="727cac18-044b-4504-87f1-a5aefa774bda" TYPE="ext3"

Show UUID data for all partitions:

topher@crucible:~$ sudo blkid
/dev/sda1: UUID="727cac18-044b-4504-87f1-a5aefa774bda" TYPE="ext3"
/dev/sdb: UUID="467c4aa9-963d-4467-8cd0-d58caaacaff4" TYPE="ext3"

Show UUID data for all partitions in easier to read format: (Note: in newer releases, blkid -L has a different meaning, and blkid -o list should be used instead)

topher@crucible:~$ sudo blkid -L
device     fs_type label    mount point    UUID
-------------------------------------------------------------------------------
/dev/sda1 ext3             /              727cac18-044b-4504-87f1-a5aefa774bda
/dev/sdc  ext3             /home          467c4aa9-963d-4467-8cd0-d58caaacaff4

Show just the UUID for /dev/sda1 and nothing else:

topher@crucible:~$ sudo blkid -s UUID -o value /dev/sda1
727cac18-044b-4504-87f1-a5aefa774bda

Answer 2

For GPT Partitioned Disks Only

On a GPT formatted disk each partition is assigned a GUID, which is a form of UUID, though probably not what the original poster was referring to. Therefore this answer is probably less helpful to the original questioner. Nevertheless I believe there's an important distinction to be noticed.

To get the GUID of partition 1 on GPT formatted disk /dev/sda, as well as its partition label and so on:

sudo sgdisk -i 1 /dev/sda

or all with:

ls -l /dev/disk/by-partuuid

To boot with the root of the file system being on a certain partition you would use the linux kernel parameter syntax of:

root=PARTUUID=87654321-4321-4321-abcd-123456789012

In this case you can specify just the beginning of the UUID--enough to be unique. This parameter is more primitive and can be understood by the kernel earlier in its boot process.

---

There's a difference in semantics between these:

A disk holds partitions, a partition holds a file system, a file system holds directories and files. For some set-ups and operating systems there are more layers.

The GUID UUID and associated label refer to a partition, but not the partition's contents. A new partition on the same disk, or a partition on a new disk will have a new GUID UUID. The same partition could hold one file system one day and another on a different day. It only exists for GPT formatted disks, but not for legacy partitioned disks. There's usually no more utility here than specifying root=/dev/sda1 or root=8:1.

The other current answers refer to the UUID of a file system in some containing partition. If the file system is copied, as a whole, to another partition or hard disk that value remains the same. This UUID is useful in finding a moved file system. Therefore this is probably more pertinent to most people. Linux kernel parameter root=UUID=87654321-4321-4321-a567-123456789012 refers to this.

I believe root=LABEL= and root=UUID= are implemented by early userspace, the init code I saw the other day on my system translated these parameters to /dev/disk/by-uuid and /dev/disk/by-label (links I believe are created by udev in userspace on my system).

[1] http://git.kernel.org/cgit/linux/kernel/git/torvalds/linux.git/tree/init/do_mounts.c#n183

Answer 3

The script-clean way to do this which works on any type of filesystem is:

lsblk -no UUID <device-containing-FS>

Or, given the mountpoint (or any file within it):

lsblk -no UUID $(df -P <file> | awk 'END{print $1}')

The output is the UUID, the whole UUID, and nothing but the UUID.

Answer 4

The easiest way to do this for ext2/ext3/ext4 is:

/sbin/tune2fs -l /dev/sda1

Answer 5

The recommended way to do this is to do

sudo vol_id -u /dev/sda2

For more on using UUIDs, see this article (from ubuntu help, but should work for any linux distro using UUIDs).

As noted in comments to this question, vol_id may not be in your path. On ubuntu it is in /sbin so the above will work. For fedora it appears to need

sudo /lib/udev/vol_id -u /dev/sda2

If other distributions have vol_id in other places then post a comment and I'll add it to this answer.

Answer 6

This seems to work for me:

sudo dumpe2fs /dev/sda1 | grep UUID

Answer 7

Assuming you want the UUID for sda1, you could try something like this:

for v in /dev/disk/by-uuid/* ; do echo "`readlink $v`: $v" | grep ../sda1 | cut -d\: -f2 | cut -d/ -f5 ; done

Adjust sda1 accordingly. To get the UUIDs for all partitions, drop the greps and cuts, a la:

for v in /dev/disk/by-uuid/* ; do echo "`readlink $v`: $v" ; done

Sample output for sda1 on my desktop:

[mihailim@home ~]$ for v in /dev/disk/by-uuid/* ; do echo "`readlink $v`: $v" | grep ../sdb3 | cut -d\: -f2 | cut -d/ -f5 ; done
dc8c49f1-e2dc-46bc-ba02-013f26c85f70

Edit: Please note that this solution, while more contrived than the udev->vol_id one, does not require root privileges, will work on any post-2005 or so kernel, and relies on tools present in any Linux distribution which are by default in the path for any user.

Answer 8

The simplest and best way to find the UUID of a filesystem

[root@server ~]# blkid /dev/sda1

Answer 9

You can use the following to get the UUID for a particular drive,

sudo vol_id -u /dev/sda1

Answer 10

You can also use this to print all the UUIDs:

for disk in /dev/disk/by-uuid/*; do 
    basename "$(readlink "$disk")"
    basename "$disk"
    echo
done

or this arguably simpler command, replacing sda1 with the device you'd like to search for:

disk=sda1
find /dev/disk/by-uuid -type l -exec sh -c "readlink {} | grep -o $disk && basename {}" \;

an adaptation of the second method to print all UUIDs:

find /dev/disk/by-uuid -type l -exec sh -c 'basename $(readlink {}); basename {}; echo' \;

Answer 11

ls -l /dev/disk/by-uuid | grep `lsblk | grep "/" | awk '{print $1}'` | awk '{print $9}'

The above seems to work on most (all I have found) Linux systems over many years. It may have flaws, I don't know. I would prefer to get the serial number but ... this is the UUID of the root filesystem.

If anyone has a way to get the serial number without needing to be root (as mine is) and not installing "unusual" packages that are different in different versions of Unix I would appreciate it - always can learn something. And I am aware I am mixing things - the is the root file system UUID, not a disk.

The purpose, BTW, is to generate a unique number per machine that cannot be modified (like a disk serial number and like MAC addresses once were long ago).

It is used for encoding of software to a single machine. MAC address was fine until they allowed them to be virtual ... some sleazy customers have simply set their MAC address to a constant (on different networks of course) and avoided paying me.

In AIX there is a single call to get one number that identifies the machine. It does not care if the hardware changes or software updates occur so I have no idea how they do it ... If the motherboard changes, then the number changes, so I think they hide it there. And that is beyond rare.

Answer 12

You can use the following to get the UUID for a particular drive,

sudo vol_id -u /dev/sda1

or you can use this to list all UUIDs for the attached media,

ls /dev/disk/by-uuid