libuuid(3) [redhat man page]

LIBUUID(3)						     Library Functions Manual							LIBUUID(3)

NAME

       libuuid - DCE compatible Universally Unique Identifier library

SYNOPSIS

       #include <uuid/uuid.h>

       cc file.c -luuid

DESCRIPTION

       The libuuid library is used to generate unique identifiers for objects that may be accessible beyond the local system.  The Linux implemen-
       tation was created to uniquely identify ext2 filesystems created by a machine.  This library generates UUIDs compatible with those  created
       by the Open Software Foundation (OSF) Distributed Computing Environment (DCE) utility uuidgen.

       The  UUIDs generated by this library can be reasonably expected to be unique within a system, and unique across all systems.  They could be
       used, for instance, to generate unique HTTP cookies across multiple web servers without communication between the servers, and without fear
       of a name clash.

CONFORMING TO

       OSF DCE 1.1

AUTHOR

       libuuid was written by Theodore Y. Ts'o for the ext2 filesystem utilties.

AVAILABILITY

       libuuid is part of the e2fsprogs package and is available from http://e2fsprogs.sourceforge.net/ <http://e2fsprogs.sourceforge.net/>

COPYING

       libuuid is available under the terms of the GNU Library General Public License (LGPL), version 2 (or at your discretion any later version).
       A copy of the LGPL should be included with this library in the file COPYING.  If not, write to
	      Free Software Foundation, Inc.
	      59 Temple Place
	      Suite 330
	      Boston, MA  02111-1307  USA

       or visit http://www.gnu.org/licenses/licenses.html#LGPL <http://www.gnu.org/licenses/licenses.html#LGPL>

SEE ALSO

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

E2fsprogs version 1.32						   November 2002							LIBUUID(3)

UUID_GENERATE(3)					     Library Functions Manual						  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

       http://e2fsprogs.sourceforge.net/ <http://e2fsprogs.sourceforge.net/>

SEE ALSO

       uuid(3), uuidgen(1), uuid_clear(3), uuid_compare(3), uuid_copy(3), uuid_is_null(3), uuid_parse(3), uuid_unparse(3)

1.36								    April 2004							  UUID_GENERATE(3)