So many formats, So few packages

[Jeff Johnson]

On Apr 11, 2011, at 5:52 PM, Jordan K. Hubbard wrote:

> 
> On Apr 11, 2011, at 6:18 AM, Jeff Johnson wrote:
> 
>> You seem to be asking where you can read about how Mac OS X uses UUID's, and
>> you'll have to ask Jordan about that. I can describe how UUID's are being generated
>> in RPM metadata if you wish. How the UUID is generated by RPM isn't as important that
>> UUID's can be generated by others in the same fashion, or by using the same tool.
> 
> I covered some of the "how they're used" questions in my previous email, but I realize that I didn't touch on how they're generated.  On Mac OS X, this is very simple:
> 
> jkh at hosebox-> uuidgen 
> 251F37CA-F68D-4083-815D-C36973E34A0D
> 
> A timestamp is one of the datum which goes into this value, helping to assure that it's always unique.
> 

Um, no.

$ uuid -d 251F37CA-F68D-4083-815D-C36973E34A0D
encode: STR:     251f37ca-f68d-4083-815d-c36973e34a0d
        SIV:     49343528659577571291111566205861972493
decode: variant: DCE 1.1, ISO/IEC 11578:1996
        version: 4 (random data based)
        content: 25:1F:37:CA:F6:8D:00:83:01:5D:C3:69:73:E3:4A:0D
                 (no semantics: random data only)

A UUIDv4 is just random bit soup. "works" as an identifier only.

Anyone is free to generate a UUIDv4 anytime they choose.

73 de Jeff
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