opendarwin man page for 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 identifier (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 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 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 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
       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)