How to find disk partition UUIDs in Linux

A Universally Unique IDentifier (UUID) is a randomly generated 128-bit value assigned to partitions or block devices in Linux systems. UUIDs provide a more stable and reliable method of identifying partitions than traditional device names, such as /dev/sda1. UUIDs can be used for mounting filesystems via /etc/fstab by specifying the UUID value in a special block device (the first field).

UUIDs are typically symbolic links to the actual device names within the /dev directory. To retrieve a partition's UUID, you can browse the /dev/disk/by-uuid/ directory or use various command-line utilities available in Linux.

1. Launch the terminal.
2. List partition UUIDs from the /dev 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 absolute path for ../../sda3 is /dev/sda3

3. Get 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"

   blkid is installed by default in most Linux distributions.

4. Find the UUID for a specific partition.

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

   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).