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)