Universally Unique IDentifier
or UUID
is a random 128-bit value that's generated and can be assigned to partitions or block devices. The partitions or block devices could then be identified using UUID
instead of the normal device name such as /dev/sda1
. This can then be used to mount filesystem via /etc/fstab
by specifying UUID
value in block special device (the first field).
UUID
normally is just a symlink to the actual device name and could be manually found within the /dev
directory. You could also use specific program to get UUID
for partitions or block devices from the terminal in Linux
.
/dev/disk/by-uuid/
via ls
using long listing format.$ ls -l /dev/disk/by-uuid/ total 0 lrwxrwxrwx 1 root root 9 Aug 22 2019 2019-04-16-20-20-34-00 -> ../../sr0 lrwxrwxrwx 1 root root 10 Aug 22 2019 84a42ad4-c261-4ed7-a428-33f648f959df -> ../../sda2
The absolute path for ../../sda2
is /dev/sda2
blkid
command. $ sudo blkid /dev/sr0: UUID="2019-04-16-20-20-34-00" LABEL="Ubuntu-Server 19.04 amd64" TYPE="iso9660" PTUUID="73a9f942" PTTYPE="dos" /dev/sda2: UUID="84a42ad4-c261-4ed7-a428-33f648f959df" TYPE="ext4" PARTUUID="c373394c-81af-4e90-985e-1a51805cdf57"
blkid
is installed by default in most Linux
distributions.
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).
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