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Re: [Gnu-arch-users] Newbie - don't quite understand tagging method

From: Charles Duffy
Subject: Re: [Gnu-arch-users] Newbie - don't quite understand tagging method
Date: Thu, 27 Nov 2003 19:25:27 -0500
User-agent: Internet Messaging Program (IMP) 4.0-cvs

Quoting David Allouche <address@hidden>:

> On Thu, Nov 27, 2003 at 11:46:33AM -0500, Robert Anderson wrote:
> > A pretty good template is:
> >
> > echo "# arch-tag: `uuidgen`" >>
> It is probably okay, but for the paranoids, it is better to use
> something you KNOW is going to be unique. It feels uncomfortable to rely
> on random numbers to be unique...

Let me help you get comfortable. :)

There's a standard algorithm for calculating UUIDs. It includes not only random
bits but also the current system's hardware ethernet address; read ISO-11578
for more details. I can't say with certainty that uuidgen conforms to this
standard -- but it *also* has a time-based mode (default of no sufficiently
strong random-number generator is available) which generates a uuid "based on
the current time and hardware ethernet address".

So, don't trust random numbers for your uuids, despite the fantastically low
probability of a collision and the fact that arch will inform you if one should
somehow occur? Use "uuidgen -t"!

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