uuidgen(1)

1UUIDGEN(1)                       User Commands                      UUIDGEN(1)
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NAME

6       uuidgen - create a new UUID value
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SYNOPSIS

9       uuidgen [options]
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DESCRIPTION

12       The uuidgen program creates (and prints) a new universally unique iden‐
13       tifier (UUID) using the libuuid(3) library.  The new UUID  can  reason‐
14       ably  be considered unique among all UUIDs created on the local system,
15       and among UUIDs created on other systems in the past and in the future.
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17       There are three types of UUIDs which uuidgen can  generate:  time-based
18       UUIDs,  random-based  UUIDs,  and hash-based UUIDs.  By default uuidgen
19       will generate a random-based UUID if a high-quality random number  gen‐
20       erator is present.  Otherwise, it will choose a time-based UUID.  It is
21       possible to force the generation of one of these first two  UUID  types
22       by using the --random or --time options.
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24       The  third  type of UUID is generated with the --md5 or --sha1 options,
25       followed by --namespace namespace and --name name.  The  namespace  may
26       either  be a well-known UUID, or else an alias to one of the well-known
27       UUIDs defined in RFC 4122, that is @dns, @url,  @oid,  or  @x500.   The
28       name is an arbitrary string value.  The generated UUID is the digest of
29       the concatenation of the namespace UUID and the name value, hashed with
30       the  MD5  or  SHA1  algorithms.   It is, therefore, a predictable value
31       which may be useful when UUIDs are being used as handles or nonces  for
32       more  complex  values  or values which shouldn't be disclosed directly.
33       See the RFC for more information.
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OPTIONS

36       -r, --random
37              Generate a random-based UUID.  This method creates a  UUID  con‐
38              sisting  mostly  of random bits.  It requires that the operating
39              system have a high quality  random  number  generator,  such  as
40              /dev/random.
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42       -t, --time
43              Generate a time-based UUID.  This method creates a UUID based on
44              the system clock plus the system's ethernet hardware address, if
45              present.
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47       -h, --help
48              Display help text and exit.
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50       -V, --version
51              Display version information and exit.
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53       -m, --md5
54              Use MD5 as the hash algorithm.
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56       -s, --sha1
57              Use SHA1 as the hash algorithm.
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59       -n, --namespace namespace
60              Generate  the  hash  with the namespace prefix. The namespace is
61              UUID,  or  '@ns'  where  "ns"  is  well-known  predefined   UUID
62              addressed by namespace name (see above).
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64       -N, --name name
65              Generate the hash of the name.
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67       -x, --hex
68              Interpret name name as a hexadecimal string.
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CONFORMING TO

71       OSF DCE 1.1
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EXAMPLES

74       uuidgen --sha1 --namespace @dns --name "www.example.com"
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AUTHOR

77       uuidgen was written by Andreas Dilger for libuuid.
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AVAILABILITY

83       The  uuidgen command is part of the util-linux package and is available
84       from https://www.kernel.org/pub/linux/utils/util-linux/.
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88util-linux                         June 2011                        UUIDGEN(1)