Re: [PATCH 02/11] config-batch: create parse loop and unknown command

> From: Derrick Stolee <stolee@gmail.com>
> 
> As we build new features in the config-batch command, we define the
> plaintext protocol with line-by-line output and responses. To think to the
> future, we make sure that the protocol has a clear way to respond to an
> unknown command or an unknown version of that command.
> 
> As some commands will allow the final argument to contain spaces or even be
> able to parse "\ " as a non-split token, we only provide the remaining line
> as data.
> 
> Signed-off-by: Derrick Stolee <stolee@gmail.com>
> ---
>  Documentation/git-config-batch.adoc |  23 ++++-
>  builtin/config-batch.c              | 133 +++++++++++++++++++++++++++-
>  t/t1312-config-batch.sh             |  19 +++-
>  3 files changed, 170 insertions(+), 5 deletions(-)
> 
> diff --git a/Documentation/git-config-batch.adoc b/Documentation/git-config-batch.adoc
> index dfa0bd83e2..9ca04b0c1e 100644
> --- a/Documentation/git-config-batch.adoc
> +++ b/Documentation/git-config-batch.adoc
> @@ -13,7 +13,28 @@ SYNOPSIS
>  
>  DESCRIPTION
>  -----------
> -TODO
> +Tools frequently need to change their behavior based on values stored in
> +Git's configuration files. These files may have complicated conditions
> +for including extra files, so it is difficult to produce an independent
> +parser. To avoid executing multiple processes to discover or modify
> +multiple configuration values, the `git config-batch` command allows a
> +single process to handle multiple requests using a machine-parseable
> +interface across `stdin` and `stdout`.
> +
> +PROTOCOL
> +--------
> +By default, the protocol uses line feeds (`LF`) to signal the end of a

> +command over `stdin` or a response over `stdout`.
> +
> +The protocol will be extended in the future, and consumers should be
> +resilient to older Git versions not understanding the latest command
> +set. Thus, if the Git version includes the `git config-batch` builtin
> +but doesn't understand an input command, it will return a single line
> +response:
> +
> +```
> +unknown_command LF> +```
>