UUIDGEN(1)                      User Commands                     UUIDGEN(1)

NAME         top

       uuidgen - create a new UUID value

SYNOPSIS         top

       uuidgen [options]

DESCRIPTION         top

       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 -r or -t options.

       The third type of UUID is generated with the -m or -s options (MD5 or
       SHA1, respectively), followed by -n namespace and -N 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 concatentation 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

OPTIONS         top

       -r, --random
              Generate a random-based UUID.  This method creates a UUID
              consisting mostly of random bits.  It requires that the
              operating system have 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
              Display version information and exit.

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

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

       -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.

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

CONFORMING TO         top

       OSF DCE 1.1

AUTHOR         top

       uuidgen was written by Andreas Dilger for libuuid.

SEE ALSO         top

       libuuid(3), RFC 4122

AVAILABILITY         top

       The uuidgen command is part of the util-linux package and is
       available from

COLOPHON         top

       This page is part of the util-linux (a random collection of Linux
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util-linux                        June 2011                       UUIDGEN(1)

Pages that refer to this page: uuidparse(1)uuid_generate(3)swaplabel(8)uuidd(8)