uuidgen

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 iden-
       tifier (UUID) using the libuuid(3) library.  The new UUID  can  reason-
       ably  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  gen-
       erator 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 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 information.

OPTIONS
       -r, --random
              Generate a random-based UUID.  This method creates a  UUID  con-
              sisting  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
       OSF DCE 1.1

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

AUTHOR
       uuidgen was written by Andreas Dilger for libuuid.

SEE ALSO
       libuuid(3), RFC 4122

AVAILABILITY
       The  uuidgen command is part of the util-linux package and is available
       from https://www.kernel.org/pub/linux/utils/util-linux/.

util-linux                         June 2011                        UUIDGEN(1)
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