Re: Version numbers for VCS snapshots

[Alex Kost]

Leo Famulari (2016-02-21 07:35 +0300) wrote:

> On Thu, Jan 21, 2016 at 10:05:36PM +0100, Ludovic Courtès wrote:
[...]
>> I prefer 7!  This is how Git usually truncates SHA1s, so it can’t be wrong.
>
> I stumbled across this email earlier, which reminded me of this
> discussion about hash lengths:
> https://lkml.org/lkml/2010/10/28/287
>
> There are currently 13 7-character hash collisions in Guix's git repo:
>
> $ git rev-list --objects --all | cut -c1-7 | sort | uniq -dc
>       2 0d2b24c
>       2 11e0632
>       2 1f3ab8d
>       2 229bd6c
>       2 7c4a7b7
>       2 9ff8b63
>       2 aa27b56
>       2 c10c562
>       2 d96cdce
>       2 dab4329
>       2 dc27d1c
>       2 ea119a2
>       2 f56cc27

Hm, when I tried "git rev-list --objects --all" I got some ridiculous
number of lines (I pressed C-c C-c after about 78000 lines).  Does this
command really do what you wanted?  (I'm sorry I didn't RTFM well enough
to understand what it does).

I'm not sure if the following command is correct to find such
collisions, but it gives nothing (i.e., no collisions):

  git log --oneline | cut -c1-7 | sort | uniq -dc

-- 
Alex