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NAME | SYNOPSIS | DESCRIPTION | OPTIONS | CONFORMING TO | EXAMPLES | AUTHORS | 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 concatenation 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 has 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 algorithm.
-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 hexadecimal 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
2020-12-18. (At that time, the date of the most recent commit
that was found in the repository was 2020-12-17.) 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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