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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | CONFORMING TO | EXAMPLES | AUTHOR | SEE ALSO | AVAILABILITY | COLOPHON |
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UUIDGEN(1) User Commands UUIDGEN(1)
uuidgen - create a new UUID value
uuidgen [options]
The uuidgen program creates (and prints) a new universally unique
identifier (UUID) using the libuuid(3) library. 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.
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.
-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.
OSF DCE 1.1
uuidgen --sha1 --namespace @dns --name "www.example.com"
uuidgen was written by Andreas Dilger for libuuid.
libuuid(3), RFC 4122
The uuidgen command is part of the util-linux package and is
available from https://www.kernel.org/pub/linux/utils/util-linux/.
This page is part of the util-linux (a random collection of Linux
utilities) project. Information about the project can be found at
⟨https://www.kernel.org/pub/linux/utils/util-linux/⟩. If you have a
bug report for this manual page, send it to
util-linux@vger.kernel.org. This page was obtained from the
project's upstream Git repository
⟨git://git.kernel.org/pub/scm/utils/util-linux/util-linux.git⟩ on
2018-02-02. (At that time, the date of the most recent commit that
was found in the repository was 2018-02-01.) If you discover any
rendering problems in this HTML version of the page, or you believe
there is a better or more up-to-date source for the page, or you have
corrections or improvements to the information in this COLOPHON
(which is not part of the original manual page), send a mail to
man-pages@man7.org
util-linux June 2011 UUIDGEN(1)
Pages that refer to this page: uuidparse(1), uuid_generate(3), swaplabel(8), uuidd(8)
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