1 2 :mod:`uuid` --- UUID objects according to RFC 4122 3 ================================================== 4 5 .. module:: uuid 6 :synopsis: UUID objects (universally unique identifiers) according to RFC 4122 7 .. moduleauthor:: Ka-Ping Yee <ping (a] zesty.ca> 8 .. sectionauthor:: George Yoshida <quiver (a] users.sourceforge.net> 9 10 11 .. versionadded:: 2.5 12 13 This module provides immutable :class:`UUID` objects (the :class:`UUID` class) 14 and the functions :func:`uuid1`, :func:`uuid3`, :func:`uuid4`, :func:`uuid5` for 15 generating version 1, 3, 4, and 5 UUIDs as specified in :rfc:`4122`. 16 17 If all you want is a unique ID, you should probably call :func:`uuid1` or 18 :func:`uuid4`. Note that :func:`uuid1` may compromise privacy since it creates 19 a UUID containing the computer's network address. :func:`uuid4` creates a 20 random UUID. 21 22 23 .. class:: UUID([hex[, bytes[, bytes_le[, fields[, int[, version]]]]]]) 24 25 Create a UUID from either a string of 32 hexadecimal digits, a string of 16 26 bytes as the *bytes* argument, a string of 16 bytes in little-endian order as 27 the *bytes_le* argument, a tuple of six integers (32-bit *time_low*, 16-bit 28 *time_mid*, 16-bit *time_hi_version*, 8-bit *clock_seq_hi_variant*, 8-bit 29 *clock_seq_low*, 48-bit *node*) as the *fields* argument, or a single 128-bit 30 integer as the *int* argument. When a string of hex digits is given, curly 31 braces, hyphens, and a URN prefix are all optional. For example, these 32 expressions all yield the same UUID:: 33 34 UUID('{12345678-1234-5678-1234-567812345678}') 35 UUID('12345678123456781234567812345678') 36 UUID('urn:uuid:12345678-1234-5678-1234-567812345678') 37 UUID(bytes='\x12\x34\x56\x78'*4) 38 UUID(bytes_le='\x78\x56\x34\x12\x34\x12\x78\x56' + 39 '\x12\x34\x56\x78\x12\x34\x56\x78') 40 UUID(fields=(0x12345678, 0x1234, 0x5678, 0x12, 0x34, 0x567812345678)) 41 UUID(int=0x12345678123456781234567812345678) 42 43 Exactly one of *hex*, *bytes*, *bytes_le*, *fields*, or *int* must be given. 44 The *version* argument is optional; if given, the resulting UUID will have its 45 variant and version number set according to RFC 4122, overriding bits in the 46 given *hex*, *bytes*, *bytes_le*, *fields*, or *int*. 47 48 :class:`UUID` instances have these read-only attributes: 49 50 51 .. attribute:: UUID.bytes 52 53 The UUID as a 16-byte string (containing the six integer fields in big-endian 54 byte order). 55 56 57 .. attribute:: UUID.bytes_le 58 59 The UUID as a 16-byte string (with *time_low*, *time_mid*, and *time_hi_version* 60 in little-endian byte order). 61 62 63 .. attribute:: UUID.fields 64 65 A tuple of the six integer fields of the UUID, which are also available as six 66 individual attributes and two derived attributes: 67 68 +------------------------------+-------------------------------+ 69 | Field | Meaning | 70 +==============================+===============================+ 71 | :attr:`time_low` | the first 32 bits of the UUID | 72 +------------------------------+-------------------------------+ 73 | :attr:`time_mid` | the next 16 bits of the UUID | 74 +------------------------------+-------------------------------+ 75 | :attr:`time_hi_version` | the next 16 bits of the UUID | 76 +------------------------------+-------------------------------+ 77 | :attr:`clock_seq_hi_variant` | the next 8 bits of the UUID | 78 +------------------------------+-------------------------------+ 79 | :attr:`clock_seq_low` | the next 8 bits of the UUID | 80 +------------------------------+-------------------------------+ 81 | :attr:`node` | the last 48 bits of the UUID | 82 +------------------------------+-------------------------------+ 83 | :attr:`time` | the 60-bit timestamp | 84 +------------------------------+-------------------------------+ 85 | :attr:`clock_seq` | the 14-bit sequence number | 86 +------------------------------+-------------------------------+ 87 88 89 .. attribute:: UUID.hex 90 91 The UUID as a 32-character hexadecimal string. 92 93 94 .. attribute:: UUID.int 95 96 The UUID as a 128-bit integer. 97 98 99 .. attribute:: UUID.urn 100 101 The UUID as a URN as specified in RFC 4122. 102 103 104 .. attribute:: UUID.variant 105 106 The UUID variant, which determines the internal layout of the UUID. This will be 107 one of the integer constants :const:`RESERVED_NCS`, :const:`RFC_4122`, 108 :const:`RESERVED_MICROSOFT`, or :const:`RESERVED_FUTURE`. 109 110 111 .. attribute:: UUID.version 112 113 The UUID version number (1 through 5, meaningful only when the variant is 114 :const:`RFC_4122`). 115 116 The :mod:`uuid` module defines the following functions: 117 118 119 .. function:: getnode() 120 121 Get the hardware address as a 48-bit positive integer. The first time this 122 runs, it may launch a separate program, which could be quite slow. If all 123 attempts to obtain the hardware address fail, we choose a random 48-bit number 124 with its eighth bit set to 1 as recommended in RFC 4122. "Hardware address" 125 means the MAC address of a network interface, and on a machine with multiple 126 network interfaces the MAC address of any one of them may be returned. 127 128 .. index:: single: getnode 129 130 131 .. function:: uuid1([node[, clock_seq]]) 132 133 Generate a UUID from a host ID, sequence number, and the current time. If *node* 134 is not given, :func:`getnode` is used to obtain the hardware address. If 135 *clock_seq* is given, it is used as the sequence number; otherwise a random 136 14-bit sequence number is chosen. 137 138 .. index:: single: uuid1 139 140 141 .. function:: uuid3(namespace, name) 142 143 Generate a UUID based on the MD5 hash of a namespace identifier (which is a 144 UUID) and a name (which is a string). 145 146 .. index:: single: uuid3 147 148 149 .. function:: uuid4() 150 151 Generate a random UUID. 152 153 .. index:: single: uuid4 154 155 156 .. function:: uuid5(namespace, name) 157 158 Generate a UUID based on the SHA-1 hash of a namespace identifier (which is a 159 UUID) and a name (which is a string). 160 161 .. index:: single: uuid5 162 163 The :mod:`uuid` module defines the following namespace identifiers for use with 164 :func:`uuid3` or :func:`uuid5`. 165 166 167 .. data:: NAMESPACE_DNS 168 169 When this namespace is specified, the *name* string is a fully-qualified domain 170 name. 171 172 173 .. data:: NAMESPACE_URL 174 175 When this namespace is specified, the *name* string is a URL. 176 177 178 .. data:: NAMESPACE_OID 179 180 When this namespace is specified, the *name* string is an ISO OID. 181 182 183 .. data:: NAMESPACE_X500 184 185 When this namespace is specified, the *name* string is an X.500 DN in DER or a 186 text output format. 187 188 The :mod:`uuid` module defines the following constants for the possible values 189 of the :attr:`variant` attribute: 190 191 192 .. data:: RESERVED_NCS 193 194 Reserved for NCS compatibility. 195 196 197 .. data:: RFC_4122 198 199 Specifies the UUID layout given in :rfc:`4122`. 200 201 202 .. data:: RESERVED_MICROSOFT 203 204 Reserved for Microsoft compatibility. 205 206 207 .. data:: RESERVED_FUTURE 208 209 Reserved for future definition. 210 211 212 .. seealso:: 213 214 :rfc:`4122` - A Universally Unique IDentifier (UUID) URN Namespace 215 This specification defines a Uniform Resource Name namespace for UUIDs, the 216 internal format of UUIDs, and methods of generating UUIDs. 217 218 219 .. _uuid-example: 220 221 Example 222 ------- 223 224 Here are some examples of typical usage of the :mod:`uuid` module:: 225 226 >>> import uuid 227 228 >>> # make a UUID based on the host ID and current time 229 >>> uuid.uuid1() 230 UUID('a8098c1a-f86e-11da-bd1a-00112444be1e') 231 232 >>> # make a UUID using an MD5 hash of a namespace UUID and a name 233 >>> uuid.uuid3(uuid.NAMESPACE_DNS, 'python.org') 234 UUID('6fa459ea-ee8a-3ca4-894e-db77e160355e') 235 236 >>> # make a random UUID 237 >>> uuid.uuid4() 238 UUID('16fd2706-8baf-433b-82eb-8c7fada847da') 239 240 >>> # make a UUID using a SHA-1 hash of a namespace UUID and a name 241 >>> uuid.uuid5(uuid.NAMESPACE_DNS, 'python.org') 242 UUID('886313e1-3b8a-5372-9b90-0c9aee199e5d') 243 244 >>> # make a UUID from a string of hex digits (braces and hyphens ignored) 245 >>> x = uuid.UUID('{00010203-0405-0607-0809-0a0b0c0d0e0f}') 246 247 >>> # convert a UUID to a string of hex digits in standard form 248 >>> str(x) 249 '00010203-0405-0607-0809-0a0b0c0d0e0f' 250 251 >>> # get the raw 16 bytes of the UUID 252 >>> x.bytes 253 '\x00\x01\x02\x03\x04\x05\x06\x07\x08\t\n\x0b\x0c\r\x0e\x0f' 254 255 >>> # make a UUID from a 16-byte string 256 >>> uuid.UUID(bytes=x.bytes) 257 UUID('00010203-0405-0607-0809-0a0b0c0d0e0f') 258 259
