1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
|
:mod:`uuid` --- UUID objects according to :rfc:`4122`
=====================================================
.. module:: uuid
:synopsis: UUID objects (universally unique identifiers) according to RFC 4122
.. moduleauthor:: Ka-Ping Yee <ping@zesty.ca>
.. sectionauthor:: George Yoshida <quiver@users.sourceforge.net>
**Source code:** :source:`Lib/uuid.py`
--------------
This module provides immutable :class:`UUID` objects (the :class:`UUID` class)
and the functions :func:`uuid1`, :func:`uuid3`, :func:`uuid4`, :func:`uuid5` for
generating version 1, 3, 4, and 5 UUIDs as specified in :rfc:`4122`.
If all you want is a unique ID, you should probably call :func:`uuid1` or
:func:`uuid4`. Note that :func:`uuid1` may compromise privacy since it creates
a UUID containing the computer's network address. :func:`uuid4` creates a
random UUID.
Depending on support from the underlying platform, :func:`uuid1` may or may
not return a "safe" UUID. A safe UUID is one which is generated using
synchronization methods that ensure no two processes can obtain the same
UUID. All instances of :class:`UUID` have an :attr:`~UUID.is_safe` attribute
which relays any information about the UUID's safety, using this enumeration:
.. class:: SafeUUID
.. versionadded:: 3.7
.. attribute:: SafeUUID.safe
The UUID was generated by the platform in a multiprocessing-safe way.
.. attribute:: SafeUUID.unsafe
The UUID was not generated in a multiprocessing-safe way.
.. attribute:: SafeUUID.unknown
The platform does not provide information on whether the UUID was
generated safely or not.
.. class:: UUID(hex=None, bytes=None, bytes_le=None, fields=None, int=None, version=None, *, is_safe=SafeUUID.unknown)
Create a UUID from either a string of 32 hexadecimal digits, a string of 16
bytes in big-endian order as the *bytes* argument, a string of 16 bytes in
little-endian order as the *bytes_le* argument, a tuple of six integers
(32-bit *time_low*, 16-bit *time_mid*, 16-bit *time_hi_version*,
8-bit *clock_seq_hi_variant*, 8-bit *clock_seq_low*, 48-bit *node*) as the
*fields* argument, or a single 128-bit integer as the *int* argument.
When a string of hex digits is given, curly braces, hyphens,
and a URN prefix are all optional. For example, these
expressions all yield the same UUID::
UUID('{12345678-1234-5678-1234-567812345678}')
UUID('12345678123456781234567812345678')
UUID('urn:uuid:12345678-1234-5678-1234-567812345678')
UUID(bytes=b'\x12\x34\x56\x78'*4)
UUID(bytes_le=b'\x78\x56\x34\x12\x34\x12\x78\x56' +
b'\x12\x34\x56\x78\x12\x34\x56\x78')
UUID(fields=(0x12345678, 0x1234, 0x5678, 0x12, 0x34, 0x567812345678))
UUID(int=0x12345678123456781234567812345678)
Exactly one of *hex*, *bytes*, *bytes_le*, *fields*, or *int* must be given.
The *version* argument is optional; if given, the resulting UUID will have its
variant and version number set according to :rfc:`4122`, overriding bits in the
given *hex*, *bytes*, *bytes_le*, *fields*, or *int*.
Comparison of UUID objects are made by way of comparing their
:attr:`UUID.int` attributes. Comparison with a non-UUID object
raises a :exc:`TypeError`.
``str(uuid)`` returns a string in the form
``12345678-1234-5678-1234-567812345678`` where the 32 hexadecimal digits
represent the UUID.
:class:`UUID` instances have these read-only attributes:
.. attribute:: UUID.bytes
The UUID as a 16-byte string (containing the six integer fields in big-endian
byte order).
.. attribute:: UUID.bytes_le
The UUID as a 16-byte string (with *time_low*, *time_mid*, and *time_hi_version*
in little-endian byte order).
.. attribute:: UUID.fields
A tuple of the six integer fields of the UUID, which are also available as six
individual attributes and two derived attributes:
.. list-table::
* - Field
- Meaning
* - .. attribute:: UUID.time_low
- The first 32 bits of the UUID.
* - .. attribute:: UUID.time_mid
- The next 16 bits of the UUID.
* - .. attribute:: UUID.time_hi_version
- The next 16 bits of the UUID.
* - .. attribute:: UUID.clock_seq_hi_variant
- The next 8 bits of the UUID.
* - .. attribute:: UUID.clock_seq_low
- The next 8 bits of the UUID.
* - .. attribute:: UUID.node
- The last 48 bits of the UUID.
* - .. attribute:: UUID.time
- The 60-bit timestamp.
* - .. attribute:: UUID.clock_seq
- The 14-bit sequence number.
.. attribute:: UUID.hex
The UUID as a 32-character lowercase hexadecimal string.
.. attribute:: UUID.int
The UUID as a 128-bit integer.
.. attribute:: UUID.urn
The UUID as a URN as specified in :rfc:`4122`.
.. attribute:: UUID.variant
The UUID variant, which determines the internal layout of the UUID. This will be
one of the constants :const:`RESERVED_NCS`, :const:`RFC_4122`,
:const:`RESERVED_MICROSOFT`, or :const:`RESERVED_FUTURE`.
.. attribute:: UUID.version
The UUID version number (1 through 5, meaningful only when the variant is
:const:`RFC_4122`).
.. attribute:: UUID.is_safe
An enumeration of :class:`SafeUUID` which indicates whether the platform
generated the UUID in a multiprocessing-safe way.
.. versionadded:: 3.7
The :mod:`uuid` module defines the following functions:
.. function:: getnode()
Get the hardware address as a 48-bit positive integer. The first time this
runs, it may launch a separate program, which could be quite slow. If all
attempts to obtain the hardware address fail, we choose a random 48-bit
number with the multicast bit (least significant bit of the first octet)
set to 1 as recommended in :rfc:`4122`. "Hardware address" means the MAC
address of a network interface. On a machine with multiple network
interfaces, universally administered MAC addresses (i.e. where the second
least significant bit of the first octet is *unset*) will be preferred over
locally administered MAC addresses, but with no other ordering guarantees.
.. versionchanged:: 3.7
Universally administered MAC addresses are preferred over locally
administered MAC addresses, since the former are guaranteed to be
globally unique, while the latter are not.
.. index:: single: getnode
.. function:: uuid1(node=None, clock_seq=None)
Generate a UUID from a host ID, sequence number, and the current time. If *node*
is not given, :func:`getnode` is used to obtain the hardware address. If
*clock_seq* is given, it is used as the sequence number; otherwise a random
14-bit sequence number is chosen.
.. index:: single: uuid1
.. function:: uuid3(namespace, name)
Generate a UUID based on the MD5 hash of a namespace identifier (which is a
UUID) and a name (which is a :class:`bytes` object or a string
that will be encoded using UTF-8).
.. index:: single: uuid3
.. function:: uuid4()
Generate a random UUID.
.. index:: single: uuid4
.. function:: uuid5(namespace, name)
Generate a UUID based on the SHA-1 hash of a namespace identifier (which is a
UUID) and a name (which is a :class:`bytes` object or a string
that will be encoded using UTF-8).
.. index:: single: uuid5
The :mod:`uuid` module defines the following namespace identifiers for use with
:func:`uuid3` or :func:`uuid5`.
.. data:: NAMESPACE_DNS
When this namespace is specified, the *name* string is a fully qualified domain
name.
.. data:: NAMESPACE_URL
When this namespace is specified, the *name* string is a URL.
.. data:: NAMESPACE_OID
When this namespace is specified, the *name* string is an ISO OID.
.. data:: NAMESPACE_X500
When this namespace is specified, the *name* string is an X.500 DN in DER or a
text output format.
The :mod:`uuid` module defines the following constants for the possible values
of the :attr:`~UUID.variant` attribute:
.. data:: RESERVED_NCS
Reserved for NCS compatibility.
.. data:: RFC_4122
Specifies the UUID layout given in :rfc:`4122`.
.. data:: RESERVED_MICROSOFT
Reserved for Microsoft compatibility.
.. data:: RESERVED_FUTURE
Reserved for future definition.
.. seealso::
:rfc:`4122` - A Universally Unique IDentifier (UUID) URN Namespace
This specification defines a Uniform Resource Name namespace for UUIDs, the
internal format of UUIDs, and methods of generating UUIDs.
.. _uuid-cli:
Command-Line Usage
------------------
.. versionadded:: 3.12
The :mod:`uuid` module can be executed as a script from the command line.
.. code-block:: sh
python -m uuid [-h] [-u {uuid1,uuid3,uuid4,uuid5}] [-n NAMESPACE] [-N NAME]
The following options are accepted:
.. program:: uuid
.. option:: -h, --help
Show the help message and exit.
.. option:: -u <uuid>
--uuid <uuid>
Specify the function name to use to generate the uuid. By default :func:`uuid4`
is used.
.. option:: -n <namespace>
--namespace <namespace>
The namespace is a ``UUID``, or ``@ns`` where ``ns`` is a well-known predefined UUID
addressed by namespace name. Such as ``@dns``, ``@url``, ``@oid``, and ``@x500``.
Only required for :func:`uuid3` / :func:`uuid5` functions.
.. option:: -N <name>
--name <name>
The name used as part of generating the uuid. Only required for
:func:`uuid3` / :func:`uuid5` functions.
.. _uuid-example:
Example
-------
Here are some examples of typical usage of the :mod:`uuid` module::
>>> import uuid
>>> # make a UUID based on the host ID and current time
>>> uuid.uuid1()
UUID('a8098c1a-f86e-11da-bd1a-00112444be1e')
>>> # make a UUID using an MD5 hash of a namespace UUID and a name
>>> uuid.uuid3(uuid.NAMESPACE_DNS, 'python.org')
UUID('6fa459ea-ee8a-3ca4-894e-db77e160355e')
>>> # make a random UUID
>>> uuid.uuid4()
UUID('16fd2706-8baf-433b-82eb-8c7fada847da')
>>> # make a UUID using a SHA-1 hash of a namespace UUID and a name
>>> uuid.uuid5(uuid.NAMESPACE_DNS, 'python.org')
UUID('886313e1-3b8a-5372-9b90-0c9aee199e5d')
>>> # make a UUID from a string of hex digits (braces and hyphens ignored)
>>> x = uuid.UUID('{00010203-0405-0607-0809-0a0b0c0d0e0f}')
>>> # convert a UUID to a string of hex digits in standard form
>>> str(x)
'00010203-0405-0607-0809-0a0b0c0d0e0f'
>>> # get the raw 16 bytes of the UUID
>>> x.bytes
b'\x00\x01\x02\x03\x04\x05\x06\x07\x08\t\n\x0b\x0c\r\x0e\x0f'
>>> # make a UUID from a 16-byte string
>>> uuid.UUID(bytes=x.bytes)
UUID('00010203-0405-0607-0809-0a0b0c0d0e0f')
.. _uuid-cli-example:
Command-Line Example
--------------------
Here are some examples of typical usage of the :mod:`uuid` command line interface:
.. code-block:: shell
# generate a random uuid - by default uuid4() is used
$ python -m uuid
# generate a uuid using uuid1()
$ python -m uuid -u uuid1
# generate a uuid using uuid5
$ python -m uuid -u uuid5 -n @url -N example.com
|