uuid — UUID objects according toRFC 4122¶

Source code:Lib/uuid.py

This module provides immutableUUID objects (theUUID class)and the functionsuuid1(),uuid3(),uuid4(),uuid5() forgenerating version 1, 3, 4, and 5 UUIDs as specified inRFC 4122.

If all you want is a unique ID, you should probably calluuid1() oruuid4(). Note thatuuid1() may compromise privacy since it createsa UUID containing the computer’s network address.uuid4() creates arandom UUID.

Depending on support from the underlying platform,uuid1() may or maynot return a “safe” UUID. A safe UUID is one which is generated usingsynchronization methods that ensure no two processes can obtain the sameUUID. All instances ofUUID have anis_safe attributewhich relays any information about the UUID’s safety, using this enumeration:

classuuid.SafeUUID¶

New in version 3.7.

safe¶

The UUID was generated by the platform in a multiprocessing-safe way.

unsafe¶

The UUID was not generated in a multiprocessing-safe way.

unknown¶

The platform does not provide information on whether the UUID wasgenerated safely or not.

classuuid.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 16bytes in big-endian order as thebytes argument, a string of 16 bytes inlittle-endian order as thebytes_le argument, a tuple of six integers(32-bittime_low, 16-bittime_mid, 16-bittime_hi_version,8-bitclock_seq_hi_variant, 8-bitclock_seq_low, 48-bitnode) as thefields argument, or a single 128-bit integer as theint argument.When a string of hex digits is given, curly braces, hyphens,and a URN prefix are all optional. For example, theseexpressions 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 ofhex,bytes,bytes_le,fields, orint must be given.Theversion argument is optional; if given, the resulting UUID will have itsvariant and version number set according toRFC 4122, overriding bits in thegivenhex,bytes,bytes_le,fields, orint.

Comparison of UUID objects are made by way of comparing theirUUID.int attributes. Comparison with a non-UUID objectraises aTypeError.

str(uuid) returns a string in the form12345678-1234-5678-1234-567812345678 where the 32 hexadecimal digitsrepresent 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-endianbyte order).

UUID.bytes_le¶

The UUID as a 16-byte string (withtime_low,time_mid, andtime_hi_versionin little-endian byte order).

UUID.fields¶

A tuple of the six integer fields of the UUID, which are also available as sixindividual attributes and two derived attributes:

UUID.hex¶

The UUID as a 32-character lowercase hexadecimal string.

UUID.int¶

The UUID as a 128-bit integer.

UUID.urn¶

The UUID as a URN as specified inRFC 4122.

UUID.variant¶

The UUID variant, which determines the internal layout of the UUID. This will beone of the constantsRESERVED_NCS,RFC_4122,RESERVED_MICROSOFT, orRESERVED_FUTURE.

UUID.version¶

The UUID version number (1 through 5, meaningful only when the variant isRFC_4122).

UUID.is_safe¶

An enumeration ofSafeUUID which indicates whether the platformgenerated the UUID in a multiprocessing-safe way.

New in version 3.7.

Theuuid module defines the following functions:

uuid.getnode()¶

Get the hardware address as a 48-bit positive integer. The first time thisruns, it may launch a separate program, which could be quite slow. If allattempts to obtain the hardware address fail, we choose a random 48-bitnumber with the multicast bit (least significant bit of the first octet)set to 1 as recommended inRFC 4122. “Hardware address” means the MACaddress of a network interface. On a machine with multiple networkinterfaces, universally administered MAC addresses (i.e. where the secondleast significant bit of the first octet isunset) will be preferred overlocally administered MAC addresses, but with no other ordering guarantees.

Changed in version 3.7:Universally administered MAC addresses are preferred over locallyadministered MAC addresses, since the former are guaranteed to beglobally unique, while the latter are not.

uuid.uuid1(node=None,clock_seq=None)¶

Generate a UUID from a host ID, sequence number, and the current time. Ifnodeis not given,getnode() is used to obtain the hardware address. Ifclock_seq is given, it is used as the sequence number; otherwise a random14-bit sequence number is chosen.

uuid.uuid3(namespace,name)¶

Generate a UUID based on the MD5 hash of a namespace identifier (which is aUUID) 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 aUUID) and a name (which is a string).

Theuuid module defines the following namespace identifiers for use withuuid3() oruuid5().

uuid.NAMESPACE_DNS¶

When this namespace is specified, thename string is a fully qualified domainname.

uuid.NAMESPACE_URL¶

When this namespace is specified, thename string is a URL.

uuid.NAMESPACE_OID¶

When this namespace is specified, thename string is an ISO OID.

uuid.NAMESPACE_X500¶

When this namespace is specified, thename string is an X.500 DN in DER or atext output format.

Theuuid module defines the following constants for the possible valuesof thevariant attribute:

uuid.RESERVED_NCS¶

Reserved for NCS compatibility.

uuid.RFC_4122¶

Specifies the UUID layout given inRFC 4122.

uuid.RESERVED_MICROSOFT¶

Reserved for Microsoft compatibility.

uuid.RESERVED_FUTURE¶

Reserved for future definition.

>>>importuuid>>># 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.bytesb'\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')