Re: How to pre-empt git pull merge error?

From: Junio C Hamano <gitster@pobox.com>
Date: Nov 27, 2013, 20:09 UTC
Message-ID: <xmqqvbzdsj2s.fsf@gitster.dls.corp.google.com>
In-Reply-To: <CALWbr2wNODeLSmQ5ztQmKVxBSguNJ1bbSbvY66sdsP09dSUUgA@mail.gmail.com>

Antoine Pelisse <apelisse@gmail.com> writes:

Show 20 quoted lines

>>> On Wed, 27 Nov 2013 15:17:27 +0000
>>> Pete Forman <petef4+usenet@gmail.com> wrote:
>>>
>>>> I am looking for a way of detecting up front whether a git pull or git
>>>> merge would fail. The sort of script I want to perform is to update a
>>>> server.
>>>>
>>>>     git fetch
>>>>     git okay
>>>>     stop server
>>>>     backup data
>>>>     git merge
>>>>     start server
>>>>
>> I don't know a simple way to do the pre-merge check without actually
>> doing the merge (other than patching git merge to add a --dry-run
>> option)
>
> Wouldn't that be a nice use-case for git-recursive-merge --index-only
> ($gmane/236753) ?

As the original mentions "error: Your local changes to ...", I do not think it would be a good fit.

I have to say that the safest and sanest way may be to:

 (1) Commit any such local change(s);

     server$ git commit -a

 (2) Pull that down to a pre-deploy repository from the "server";

     prepare$ git pull ...to grab the "local changes" above...

 (3) Merge in whatever the update you want to have on the "server";

     prepare$ git merge ...whatever...

 (4) and then stop the server, fast-forward to the result of (3),
     and then restart.

     server$ stop server
     server$ git pull --ff-only ...the prepared result of (3)...
     server$ start server