UUIDGEN(1)                       User Commands                      UUIDGEN(1)

NAME
       uuidgen - create a new UUID value

SYNOPSIS
       uuidgen [options]

DESCRIPTION
       The uuidgen program creates (and prints) a new universally unique
       identifier (UUID) using the libuuid(3) library. The new UUID can
       reasonably be considered unique among all UUIDs created on the local
       system, and among UUIDs created on other systems in the past and in the
       future.

       There are three types of UUIDs which uuidgen can generate: time-based
       UUIDs, random-based UUIDs, and hash-based UUIDs. By default uuidgen
       will generate a random-based UUID if a high-quality random number
       generator is present. Otherwise, it will choose a time-based UUID. It
       is possible to force the generation of one of these first two UUID
       types by using the --random or --time options.

       The third type of UUID is generated with the --md5 or --sha1 options,
       followed by --namespace namespace and --name name. The namespace may
       either be a well-known UUID, or else an alias to one of the well-known
       UUIDs defined in RFC 4122, that is @dns, @url, @oid, or @x500. The name
       is an arbitrary string value. The generated UUID is the digest of the
       concatenation of the namespace UUID and the name value, hashed with the
       MD5 or SHA1 algorithms. It is, therefore, a predictable value which may
       be useful when UUIDs are being used as handles or nonces for more
       complex values or values which shouldn't be disclosed directly. See the
       RFC for more information.

OPTIONS
       -r, --random
           Generate a random-based UUID. This method creates a UUID consisting
           mostly of random bits. It requires that the operating system has a
           high quality random number generator, such as /dev/random.

       -t, --time
           Generate a time-based UUID. This method creates a UUID based on the
           system clock plus the system's ethernet hardware address, if
           present.

       -h, --help
           Display help text and exit.

       -V, --version
           Print version and exit.

       -m, --md5
           Use MD5 as the hash algorithm.

       -s, --sha1
           Use SHA1 as the hash algorithm.

       -n, --namespace namespace
           Generate the hash with the namespace prefix. The namespace is UUID,
           or '@ns' where "ns" is well-known predefined UUID addressed by
           namespace name (see above).

       -N, --name name
           Generate the hash of the name.

       -C, --count num
           Generate multiple UUIDs using the enhanced capability of the
           libuuid to cache time-based UUIDs, thus resulting in improved
           performance. However, this holds no significance for other UUID
           types.

       -x, --hex
           Interpret name name as a hexadecimal string.

CONFORMING TO
       OSF DCE 1.1

EXAMPLES
       uuidgen --sha1 --namespace @dns --name "www.example.com"

AUTHORS
       uuidgen was written by Andreas Dilger for libuuid(3).

SEE ALSO
       uuidparse(1), libuuid(3), RFC 4122
       <https://tools.ietf.org/html/rfc4122>

REPORTING BUGS
       For bug reports, use the issue tracker at
       <https://github.com/util-linux/util-linux/issues>.

AVAILABILITY
       The uuidgen command is part of the util-linux package which can be
       downloaded from Linux Kernel Archive
       <https://www.kernel.org/pub/linux/utils/util-linux/>.

util-linux 2.40                   2024-04-06                        UUIDGEN(1)