UUID(3pm) User Contributed Perl Documentation UUID(3pm)
NAME
UUID - DCE compatible Universally Unique Identifier library for Perl
SYNOPSIS
use UUID 'uuid';
$string = uuid(); # generate stringified UUID
UUID::generate($uuid); # new binary UUID; prefer random
UUID::generate_random($uuid); # new binary UUID; use random
UUID::generate_time($uuid); # new binary UUID; use time
UUID::unparse($uuid, $string); # stringify $uuid; system casing
UUID::unparse_lower($uuid, $string); # force lowercase stringify
UUID::unparse_upper($uuid, $string); # force uppercase stringify
$rc = UUID::parse($string, $uuid); # map string to UUID; -1 on error
UUID::copy($dst, $src); # copy binary UUID from $src to $dst
UUID::compare($uuid1, $uuid2); # compare binary UUIDs
UUID::clear( $uuid ); # set binary UUID to NULL
UUID::is_null( $uuid ); # compare binary UUID to NULL
DESCRIPTION
The UUID library is used to generate unique identifiers for objects
that may be accessible beyond the local system. For instance, they
could be used to generate unique HTTP cookies across multiple web
servers without communication between the servers, and without fear of
a name clash.
The generated UUIDs can be reasonably expected to be unique within a
system, and unique across all systems, and are compatible with those
created by the Open Software Foundation (OSF) Distributed Computing
Environment (DCE) utility uuidgen.
FUNCTIONS
Most of the UUID functions expose the underlying libuuid C interface
rather directly. That is, many return their values in their parameters
and nothing else.
Not very Perlish, is it? It's been like that for a long time though, so
not very likely to change any time soon.
All take or return UUIDs in either binary or string format. The string
format resembles the following:
1b4e28ba-2fa1-11d2-883f-0016d3cca427
Or, in terms of printf(3) format:
"%08x-%04x-%04x-%04x-%012x"
The binary format is simply a packed 16 byte binary value.
generate( $uuid )
Generates a new binary UUID based on high quality randomness from
/dev/urandom, if available.
Alternately, the current time, the local ethernet MAC address (if
available), and random data generated using a pseudo-random generator
are used.
The previous content of $uuid, if any, is lost.
generate_random( $uuid )
Generates a new binary UUID but forces the use of the all-random
algorithm, even if a high-quality random number generator (i.e.,
/dev/urandom) is not available, in which case a pseudo-random generator
is used.
Note that the use of a pseudo-random generator may compromise the
uniqueness of UUIDs generated in this fashion.
generate_time( $uuid )
Generates a new binary UUID but 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 UUIDs, 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 generate()
function only uses this algorithm if a high-quality source of
randomness is not available.
unparse( $uuid, $string )
Converts the binary UUID in $uuid to string format and returns in
$string. The previous content of $string, if any, is lost.
The case of the hex digits returned may be upper or lower case, and is
dependent on the system-dependent local default.
unparse_lower( $uuid, $string )
Same as unparse() but $string is forced to lower case.
unparse_upper( $uuid, $string )
Same as unparse() but $string is forced to upper case.
$rc = parse( $string, $uuid )
Converts the string format UUID in $string to binary and returns in
$uuid. The previous content of $uuid, if any, is lost.
Returns 0 on success and -1 on failure. Additionally on failure, the
content of $uuid is unchanged.
clear( $uuid )
Sets $uuid equal to the value of the NULL UUID.
is_null( $uuid )
Compares the value of $uuid to the NULL UUID.
Returns 1 if NULL, and 0 otherwise.
copy( $dst, $src )
Copies the binary $src UUID to $dst.
If $src isn't a UUID, $dst is set to the NULL UUID.
compare( $uuid1, $uuid2 )
Compares two binary UUIDs.
Returns an integer less than, equal to, or greater than zero if $uuid1
is less than, equal to, or greater than $uuid2.
However, if either operand is not a UUID, falls back to a simple string
comparison returning similar values.
$string = uuid()
Creates a new string format UUID and returns it in a more Perlish way.
Functionally the equivalent of calling generate() and then unparse(),
but throwing away the intermediate binary UUID.
UUID LIBRARY
On some systems external packages will need to be installed first.
Notably, uuid-dev, libuuid-devel, or uuid-devel, depending on your
platform.
Some may also have more than one package available. It should be safe
to install all variations. The UUID installer will then opt towards the
older, faster library.
EXPORTS
None by default. All functions may be imported in the usual manner,
either individually or all at once using the ":all" tag.
TODO
Need more tests and sanity checks.
COPYRIGHT AND LICENSE
This software is Copyright (c) 2014-2016 by Rick Myers.
This is free software, licensed under:
The Artistic License 2.0 (GPL Compatible)
Details of this license can be found within the 'License' text file.
AUTHOR
Current maintainer:
Rick Myers <jrm@cpan.org>.
Authors and/or previous maintainers:
Lukas Zapletal <lzap@cpan.org>
Joseph N. Hall <joseph.nathan.hall@gmail.com>
Colin Faber <cfaber@clusterfs.com>
Peter J. Braam <braam@mountainviewdata.com>
CONTRIBUTORS
David E. Wheeler
William Faulk
gregor herrmann
Slaven Rezic
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),
perl(1).
perl v5.36.0 2022-10-19 UUID(3pm)
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