How to get disk and partition UUIDs in Linux

A UUID (Universally Unique Identifier) is a 128-bit value assigned to partitions or block devices in Linux systems. It ensures a stable method of identifying partitions, which remains consistent even if the system's hardware configuration changes. This is more reliable than traditional device names like /dev/sda1, which may vary depending on device order or boot sequences.

UUIDs are symbolic links that point to actual block devices within the /dev directory. These links are stored in the /dev/disk/by-uuid directory and can be accessed using various Linux commands. Administrators rely on UUIDs for tasks like mounting file systems via the /etc/fstab file, where they can specify the UUID instead of device names.

To find the UUID of a disk or partition, Linux offers several built-in utilities. These commands allow users to list all available UUIDs and retrieve details about specific devices. This process is crucial for managing storage devices effectively and ensuring that systems mount file systems correctly.

1. Open the terminal.
2. List the available UUIDs by accessing the /dev/disk/by-uuid directory.

   $ ls -l /dev/disk/by-uuid/
   total 0
   lrwxrwxrwx 1 root root  9 Feb  27 06:29 2020-10-22-14-30-30-00 -> ../../sr0
   lrwxrwxrwx 1 root root 10 Feb  27 06:23 9B8B-2022 -> ../../sda2
   lrwxrwxrwx 1 root root 10 Feb  27 06:23 a7d71686-0a65-4402-b6e6-b58430ef8351 -> ../../sda3

   The output will show symbolic links pointing to device files such as /dev/sda3.

3. Get the UUID for all available devices using the blkid command.

   $ blkid
   /dev/sda3: UUID="a7d71686-0a65-4402-b6e6-b58430ef8351" BLOCK_SIZE="4096" TYPE="ext4" PARTUUID="0ea90c96-1b56-4c51-b07a-02e09285f291"
   /dev/sr0: BLOCK_SIZE="2048" UUID="2020-10-22-14-30-30-00" LABEL="Ubuntu 20.10 amd64" TYPE="iso9660" PTTYPE="PMBR"

   This command provides the UUID, file system type, and other information about the devices.

   blkid is installed by default in most Linux distributions.

4. Retrieve the UUID of a specific partition by specifying the partition device file.

   $ blkid /dev/sda3
   /dev/sda3: UUID="a7d71686-0a65-4402-b6e6-b58430ef8351" BLOCK_SIZE="4096" TYPE="ext4" PARTUUID="0ea90c96-1b56-4c51-b07a-02e09285f291"

   Replace /dev/sda3 with the correct device name. The output will include the UUID and other partition details.

   More options for blkid:

   $ blkid --help
   
   Usage:
    blkid --label <label> | --uuid <uuid>
   
    blkid [--cache-file <file>] [-ghlLv] [--output <format>] [--match-tag <tag>]
          [--match-token <token>] [<dev> ...]
   
    blkid -p [--match-tag <tag>] [--offset <offset>] [--size <size>]
          [--output <format>] <dev> ...
   
    blkid -i [--match-tag <tag>] [--output <format>] <dev> ...
   
   Options:
    -c, --cache-file <file>    read from <file> instead of reading from the default
                                 cache file (-c /dev/null means no cache)
    -d, --no-encoding          don't encode non-printing characters
    -g, --garbage-collect      garbage collect the blkid cache
    -o, --output <format>      output format; can be one of:
                                 value, device, export or full; (default: full)
    -k, --list-filesystems     list all known filesystems/RAIDs and exit
    -s, --match-tag <tag>      show specified tag(s) (default show all tags)
    -t, --match-token <token>  find device with a specific token (NAME=value pair)
    -l, --list-one             look up only first device with token specified by -t
    -L, --label <label>        convert LABEL to device name
    -U, --uuid <uuid>          convert UUID to device name
    <dev>                      specify device(s) to probe (default: all devices)
   
   Low-level probing options:
    -p, --probe                low-level superblocks probing (bypass cache)
    -i, --info                 gather information about I/O limits
    -S, --size <size>          overwrite device size
    -O, --offset <offset>      probe at the given offset
    -u, --usages <list>        filter by "usage" (e.g. -u filesystem,raid)
    -n, --match-types <list>   filter by filesystem type (e.g. -n vfat,ext3)
   
    -h, --help                 display this help
    -V, --version              display version
   
   For more details see blkid(8).