uuid — UUID objects according to RFC 4122¶Source code: Lib/uuid.py
This module provides immutable UUID objects (the UUID class)
and the functions uuid1(), uuid3(), uuid4(), 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 uuid1() or
uuid4(). Note that uuid1() may compromise privacy since it creates
a UUID containing the computer’s network address. uuid4() creates a
random UUID.
uuid.UUID(hex=None, bytes=None, bytes_le=None, fields=None, int=None, version=None)¶Create a UUID from either a string of 32 hexadecimal digits, a string of 16 bytes 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
UUID.int attributes. Comparison with a non-UUID object
raises a TypeError.
str(uuid) returns a string in the form
12345678-1234-5678-1234-567812345678 where the 32 hexadecimal digits
represent the UUID.
UUID instances have these read-only attributes:
UUID.bytes¶The UUID as a 16-byte string (containing the six integer fields in big-endian byte order).
UUID.bytes_le¶The UUID as a 16-byte string (with time_low, time_mid, and time_hi_version in little-endian byte order).
UUID.fields¶A tuple of the six integer fields of the UUID, which are also available as six individual attributes and two derived attributes:
| Field | Meaning |
|---|---|
time_low |
the first 32 bits of the UUID |
time_mid |
the next 16 bits of the UUID |
time_hi_version |
the next 16 bits of the UUID |
clock_seq_hi_variant |
the next 8 bits of the UUID |
clock_seq_low |
the next 8 bits of the UUID |
node |
the last 48 bits of the UUID |
time |
the 60-bit timestamp |
clock_seq |
the 14-bit sequence number |
UUID.hex¶The UUID as a 32-character hexadecimal string.
UUID.int¶The UUID as a 128-bit integer.
UUID.urn¶The UUID as a URN as specified in RFC 4122.
UUID.variant¶The UUID variant, which determines the internal layout of the UUID. This will be
one of the constants RESERVED_NCS, RFC_4122,
RESERVED_MICROSOFT, or RESERVED_FUTURE.
The uuid module defines the following functions:
uuid.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 its eighth bit set to 1 as recommended in RFC 4122. “Hardware address” means the MAC address of a network interface, and on a machine with multiple network interfaces the MAC address of any one of them may be returned.
uuid.uuid1(node=None, clock_seq=None)¶Generate a UUID from a host ID, sequence number, and the current time. If node
is not given, 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.
uuid.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 string).
uuid.uuid4()¶Generate a random UUID.
uuid.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 string).
The uuid module defines the following namespace identifiers for use with
uuid3() or uuid5().
uuid.NAMESPACE_DNS¶When this namespace is specified, the name string is a fully-qualified domain name.
uuid.NAMESPACE_URL¶When this namespace is specified, the name string is a URL.
uuid.NAMESPACE_OID¶When this namespace is specified, the name string is an ISO OID.
uuid.NAMESPACE_X500¶When this namespace is specified, the name string is an X.500 DN in DER or a text output format.
The uuid module defines the following constants for the possible values
of the variant attribute:
uuid.RESERVED_NCS¶Reserved for NCS compatibility.
uuid.RESERVED_MICROSOFT¶Reserved for Microsoft compatibility.
uuid.RESERVED_FUTURE¶Reserved for future definition.
See also
Here are some examples of typical usage of the 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')