Re: What's the ".git/gitdir" file?

[Stefan Beller <sbeller@google.com>]

On Tue, Oct 27, 2015 at 3:04 PM, Kyle Meyer <kyle@kyleam.com> wrote:
> Hello,
>
> When a ".git" file points to another repo, a ".git/gitdir" file is
> created in that repo.
>
> For example, running
>
>     $ mkdir repo-a repo-b
>     $ cd repo-a
>     $ git init
>     $ cd ../repo-b
>     $ echo "gitdir: ../repo-a/.git" > .git
>     $ git status
>
> results in a file "repo-a/.git/gitdir" that contains
>
>     $ cat repo-a/.git/gitdir
>     .git
>
> I don't see this file mentioned in the gitrepository-layout manpage,
> and my searches haven't turned up any information on it.  What's the
> purpose of ".git/gitdir"?  Are there cases where it will contain
> something other than ".git"?
>
> Thanks.

It's designed for submodules to work IIUC.

Back in the day each git submodule had its own .git directory
keeping its local objects.

Nowadays the repository of submodule <name> is kept in the superprojects
.git/modules/<name> directory.

If you are in the submodule however you need to know where the repository is,
so we have a file pointing at ../<up until superprojects root
dir>/.git/modules/<name> directory.

If not using submodules, I'd expect that file to not be there.
If you have a file .git/gitdir which points to plain .git, this is
technically correct,
indicating where to find the repository (containing objects etc).

>
> --
> Kyle
> git version 2.6.1
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