How do I generate a GUID in Erlang?

tags:

erlang
uuid

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338

answers:

+3 Q:

How do I generate a GUID in Erlang?

I tried:

os:cmd("uuidgen -t")

: but this is platform dependant and returns a tuple. I just want a binary value which I can use.

I want something based on MAC address, 128bit, and where I can just include a module and use module:uuid() to get a string hex UUID, or module:binary_uuid, something simple like that. So far it doesn't seem to exist in Erlang.

Update:

Noone could give a correct answer so in the end I used:

hex_uuid() -> os:cmd("uuidgen").

It won't work on Windows, but works on Linux and Mac

+3 A:

Take a look here: http://github.com/travis/erlang-uuid

filippo 2010-02-17 13:26:57

Is there a BIF or a standard Erlang library to do this?

Zubair 2010-02-17 13:40:48

Have you used this library as I couldn't get it to work. <pre>uuid:v4().** exception error: no function clause matching random:uniform(281474976710656.0) in function uuid:v4/0</pre>

Zubair 2010-02-17 14:08:50

Hi I've used it in the past. Worked for me with erlang R12B, but on R13B I'm getting the same error. On github there are some forks. This one http://github.com/akreiling/erlang-uuid work on my machine

filippo 2010-02-17 19:23:21

this lib is easily fixed by changing math:pow(..) to erlang:trunc(math:pow(..))random:uniform no longer takes floats (or math:pow now returns floats)

2010-02-18 01:55:19

I think I'll pass on that, I'm looking for something that is battle tested and doesn't need patching. Thanks anyway

Zubair 2010-02-18 12:05:27

+4 A:

You can also check out how CouchDB generates UUIDs. They use 3 different methods of generating it according to taste. random, utc_random and sequential.

http://svn.apache.org/repos/asf/couchdb/trunk/src/couchdb/couch_uuids.erl

Jon Gretar 2010-02-17 13:37:54

I was hoping not to have to look at lots of source code. Its ok, a bit of a -1 for Erlang not including it in their standard libraries though

Zubair 2010-02-17 13:41:59

which one do I use if I want a truly unique UUID.

Zubair 2010-02-17 13:51:52

+1 A:

http://stackoverflow.com/questions/1657204/erlang-uuid-generator

sinnus 2010-02-17 14:13:48

As I said in another answer I already tried the UUID generator they describe in that question, and it doesn't work.

Zubair 2010-02-17 14:16:02

http://svn.apache.org/repos/asf/couchdb/trunk/src/couchdb/couch_uuids.erl works

sinnus 2010-02-17 14:37:22

Do I need to install couchdb to use it as I saw the following in the code?"-include("couch_db.hrl")."

Zubair 2010-02-17 14:48:46

http://svn.apache.org/repos/asf/couchdb/trunk/src/couchdb/couch_db.hrl

sinnus 2010-02-18 10:57:20

How are they generated, MAC and 128 bit?

Zubair 2010-02-18 12:04:46

It depends on crypto module

sinnus 2010-02-18 12:24:36

+1 A:

You'll find some functions in my lib at http://code.google.com/p/tideland-cel/source/browse/trunk/src/celutl.erl. I realized it as version 4.

Mue 2010-02-17 14:17:44

I just looked at the code but some things I wasn't sure about. How many bits is the UUID and how does it generate the uniqueness as I saw no reference to a MAC address.

Zubair 2010-02-17 14:25:25

Sorry for answering so late. There are several versions of UUIDs, see http://en.wikipedia.org/wiki/Universally_Unique_Identifier. I've just choosen v4 where it's based on random. The chance of duplicates is really low, especially in one context (set of systems generating and exchanging UUIDs).

Mue 2010-02-26 08:18:13

+1 A:

hex_uuid() -> os:cmd("uuidgen").

It won't work on Windows, but works on Linux and Mac

Zubair 2010-02-17 15:12:05

ansaurus

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How do I generate a GUID in Erlang?

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