uuid_time(3) [centos man page]

UUID_TIME(3)							    Libuuid API 						      UUID_TIME(3)

NAME

       uuid_time - extract the time at which the UUID was created

SYNOPSIS

       #include <uuid.h>

       time_t uuid_time(uuid_t uu, struct timeval *ret_tv)

DESCRIPTION

       The  uuid_time  function  extracts the time at which the supplied time-based UUID uu was created.  Note that the UUID creation time is only
       encoded within certain types of UUIDs.  This function can only reasonably expect to extract the creation time for UUIDs	created  with  the
       uuid_generate_time(3) and uuid_generate_time_safe(3) functions.	It may or may not work with UUIDs created by other mechanisms.

RETURN VALUES

       The time at which the UUID was created, in seconds since January 1, 1970 GMT (the epoch), is returned (see time(2)).  The time at which the
       UUID was created, in seconds and microseconds since the epoch, is also stored in the location pointed to by ret_tv (see gettimeofday(2)).

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), uuid_clear(3), uuid_compare(3), uuid_copy(3), uuid_generate(3), uuid_is_null(3), uuid_parse(3), uuid_unparse(3)

util-linux							     May 2009							      UUID_TIME(3)

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 subsituted.  Note that the use of a pseudo-random generator
       may compromise the uniqueness of UUID's 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 elemntary  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-ng package since version 2.15.1 and is  available  from  ftp://ftp.kernel.org/pub/linux/utils/util-linux-
       ng/.

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-ng							     May 2009							  UUID_GENERATE(3)