Re: In some rebases, `exec git -C ...` has wrong working directory

From: William Chargin <wchargin@gmail.com>
Date: Apr 27, 2018, 17:14 UTC
Message-ID: <CAFW+GMC5ST5tuSJAShDGkPeZ2ifLV1M9R3j_L+usPn+=+tAYaw@mail.gmail.com>
In-Reply-To: <nycvar.QRO.7.76.6.1804270939400.72@tvgsbejvaqbjf.bet>

Hi Johannes,

Thanks for your reply.

Part of my confusion was regarding the interaction between `-C` and `--git-dir`. For instance, we have

    $ git --git-dir target -C /tmp/tmp.Cl4aXMSVis init
    Initialized empty Git repository in /tmp/tmp.Cl4aXMSVis/target/

which makes sense and is what I expected: the `-C` and `--git-dir` values are joined, as suggested by the docs for `-C` in git(1). But with

    $ git --git-dir /tmp/tmp.Cl4aXMSVis/repo -C /tmp/tmp.Cl4aXMSVis init
    Initialized empty Git repository in /tmp/tmp.Cl4aXMSVis/repo/

it appears that the `-C` argument is ignored entirely. Is this because running `git -C foo ...` is equivalent to running `cd foo; git ...` in a shell, so when the `--git-dir` is an absolute path the value of `-C` has no effect? (Assuming that `GIT_WORK_TREE` is unset.)

In your example:

>        exec git -C /somewhere/else show HEAD:some-file >some-other-file

isn't the behavior to copy the version of `some-file` in the repository being rebased to `some-other-file` in the current working directory, such that the `-C` has no effect, because the shell redirect is not affected by the `-C`? (This is what happens for me.) If so, why include the `-C` in the command?

Show 5 quoted lines

> I do not think that we can sensibly *remove* GIT_DIR from the environment
> variables passed to the exec'ed command, as we have been doing that for
> ages, and some scripts (as demonstrated above) started relying on that
> behavior. So if we changed it, we would break backwards-compatibility,
> which is something we try to avoid very much in Git.

This makes sense; understood and agreed.

Do you know why `rebase --root` does not set `GIT_DIR`?

> Maybe you could a contribute a patch to the documentation?

Sure; I'd be happy to do that once I understand this a bit better. :-)

Best, WC