UUID
This article is a stub and needs to be finished. Plunge forward and help it grow! This article only describes the use of UUIDs for the identification of filesystems and paritions.
A UUID or universally unique identifier is a label given to objects and used to refer to them to avoid collision with other objects.
Background
To create an extreme amount of entropy, UUIDs have 128 bits of random data. This makes it near impossible to regenerate the same label, even across millions of computers.
UUIDs are represented in 36-character strings. Here is an example of one:
b3c023f9-38d5-495e-a10d-edebc8ab57d9
Block Devices
UUIDs can be used to refer to block devices in Unix-like operating systems, such as in fstab(5) or crypttab(5), as a mismatch could lead to an unbootable system or data loss.
When creating a partition with, for example, fdisk(8), a UUID is generated and saved along with other metadata. Using lsblk(8), you can view the partitions and volumes of your system, along with their UUIDs:
$ lsblk -o NAME,UUID NAME UUID sda sdb ├─sdb1 6b4f9de0-4539-403a-841b-45961960dbb3 └─sdb2 d5616c8d-dfff-4366-8d9a-5e6892252829 └─root fb955ac1-ea72-48e4-b7c0-ec98648a93de sdc ├─sdc1 64A0-1B19 └─sdc2 12974f21-6ab1-4414-bf58-1477df30d725 sr0 ...
Using UUIDs
When specifying a partition using its UUID, you will simply need to prepend "UUID=" before the UUID, in place of a direct path to its block device.
In fstab(5):
/dev/sdc2 / xfs defaults 0 1
↓
UUID=12974f21-6ab1-4414-bf58-1477df30d725 / xfs defaults 0 1
or, the Linux kernel's cmdline, through GRUB's configuration file:
GRUB_CMDLINE_LINUX="root=/dev/sdc2 video=1920x1080@60Mm ..."
↓
GRUB_CMDLINE_LINUX="root=UUID=12974f21-6ab1-4414-bf58-1477df30d725 video=1920x1080@60Mm ..."