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

From: Thomas Rast <tr@thomasrast.ch>
Date: Nov 27, 2013, 19:06 UTC
Message-ID: <878uw9hdf0.fsf@thomasrast.ch>
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) ?

Possibly, but most of the use-cases for merge --dry-run are better answered by the XY Problem question:

Can you step back and explain what the *underlying* goal is?

The above sounds a lot like a deployment script, and such scripts are almost always better served by using an actual deployment tool, or failing that, by using some form of checkout -f instead, to ensure that they get whatever they are supposed to deploy.

(Using a merge to update is really terrible in the face of non-fast-forward updates, especially when caused by rewriting history to not include some commits.)

-- 
Thomas Rast
tr@thomasrast.ch