Re: behaviour of git diff, GIT_DIR & checked out tree

From: Johannes Schindelin <johannes.schindelin@gmx.de>
Date: Sep 24, 2007, 13:03 UTC
Message-ID: <Pine.LNX.4.64.0709241400410.28395@racer.site>
In-Reply-To: <e1dab3980709240545o32eeefcdkd4bc67abab0e5343@mail.gmail.com>

Hi,

On Mon, 24 Sep 2007, David Tweed wrote:

Show 13 quoted lines

> In a git tracked tree rooted at $HOME/V with
> git-dir of $HOME/V/.git, if I'm in $HOME/V then
> 
> git diff master@{midnight}
> 
> tells me the difference between the current modified files
> in the tree being tracked in V and the specified commit. In
> a different directory, OUTSIDE of $HOME/V, I tried
> 
> env GIT_DIR=$HOME/V/.git git diff master@{midnight}
> 
> to get the same effect but, whilst I do get a diff output, it
> looks like a diff of the commit against an empty tree.

Yes, this is fully expected.

The @{time} notation accesses the _reflogs_, which are purely local beasts. They are not transmitted when cloning.

The rationale: in a distributed environment, you cannot trust others' timestamps. Therefore we don't.

We can only (to a certain extent, at least) trust our _own_ timestamp. That is why we have timestamp access to the reflogs (which are purely local, as I mentioned above), but we have no way to reference commits by timestamp otherwise.

Hth, Dscho