Re: [PATCH v4 3/4] transport.c: introduce core.alternateRefsCommand

> On Mon, Oct 01, 2018 at 07:23:58PM -0700, Taylor Blau wrote:
>
> > +core.alternateRefsCommand::
> > +	When advertising tips of available history from an alternate, use the shell to
> > +	execute the specified command instead of linkgit:git-for-each-ref[1]. The
> > +	first argument is the absolute path of the alternate. Output must contain one
> > +	hex object id per line (i.e., the same as produce by `git for-each-ref
> > +	--format='%(objectname)'`).
> > ++
> > +This is useful when a repository only wishes to advertise some of its
> > +alternate's references as `.have`'s. For example, to only advertise branch
> > +heads, configure `core.alternateRefsCommand` to the path of a script which runs
> > +`git --git-dir="$1" for-each-ref --format='%(objectname)' refs/heads`.
> > ++
> > +Note that the configured value is executed in a shell, and thus
> > +linkgit:git-for-each-ref[1] by itself does not work, as scripts have to handle
> > +the path argument specially.
>
> This last paragraph is trying to fix the wrong-impression that we
> discussed in the last round. But I'm not sure it doesn't make things
> more confusing. ;)

> Specifically, the problem isn't the shell. The issue is that we pass the
> repo path as an argument to the command. So either:
>
>   - it's a real command that we run, in which case git-for-each-ref does
>     not take a repo path argument and so doesn't work; or
>
>   - it's a shell snippet, in which case the argument is appended to the
>     snippet (and here's where you can get into a rabbit hole of
>     explaining how our shell invocation works, and we should avoid that)
>
> Can we just say:
>
>   Note that you cannot generally put `git for-each-ref` directly into
>   the config value, as it does not take a repository path as an argument
>   (but you can wrap the command above in a shell script).
>
> > [...]