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uuidgen(1) [opensolaris man page]

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)

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UUID_GENERATE(3)						    Libuuid API 						  UUID_GENERATE(3)

NAME
uuid_generate, uuid_generate_random, uuid_generate_time - create a new unique UUID value SYNOPSIS
#include <uuid/uuid.h> void uuid_generate(uuid_t out); void uuid_generate_random(uuid_t out); void uuid_generate_time(uuid_t out); DESCRIPTION
The uuid_generate function creates a new universally unique identifier (UUID). The uuid will be generated based on high-quality randomness from /dev/urandom, if available. If it is not available, then uuid_generate will use an alternative algorithm which uses the current time, the local ethernet MAC address (if available), and random data generated using a pseudo-random generator. The uuid_generate_random function forces the use of the all-random UUID format, even if a high-quality random number generator (i.e., /dev/urandom) is not available, in which case a pseudo-random generator will be substituted. Note that the use of a pseudo-random genera- tor may compromise the uniqueness of UUIDs generated in this fashion. The uuid_generate_time function forces the use of the alternative algorithm which uses the current time and the local ethernet MAC address (if available). This algorithm used to be the default one used to generate UUID, but because of the use of the ethernet MAC address, it can leak information about when and where the UUID was generated. This can cause privacy problems in some applications, so the uuid_gener- ate function only uses this algorithm if a high-quality source of randomness is not available. The UUID is 16 bytes (128 bits) long, which gives approximately 3.4x10^38 unique values (there are approximately 10^80 elementary particles in the universe according to Carl Sagan's Cosmos). 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. RETURN VALUE
The newly created UUID is returned in the memory location pointed to by out. CONFORMING TO
OSF DCE 1.1 AUTHOR
Theodore Y. Ts'o AVAILABILITY
libuuid is part of the util-linux package since version 2.15.1 and is available from ftp://ftp.kernel.org/pub/linux/utils/util-linux/. SEE ALSO
uuid(3), uuidgen(1), uuid_clear(3), uuid_compare(3), uuid_copy(3), uuid_is_null(3), uuid_parse(3), uuid_time(3), uuid_unparse(3) util-linux May 2009 UUID_GENERATE(3)

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