How to do a fast-forward merge without a checkout?

How to do a fast-forward merge without a checkout?

[Patrick Doyle]

Huh?  What does he mean by that?

I have the following in my .git/config file:

[remote "origin"]
	fetch = +refs/heads/*:refs/remotes/origin/*
	url = somehost:path/to/repo
[branch "master"]
	remote = origin
	merge = refs/heads/master
[branch "wpd"]
	remote = origin
	merge = refs/heads/wpd

I have been working on my "wpd" branch on a couple of different
machines and have been happily committing, pushing, and pulling from
my "origin" host.  Recently, however, somebody committed a change on
the "master" branch.  Now, when I do a "git push", I get the following

$ git push
Counting objects: 11, done.
Delta compression using up to 2 threads.
Compressing objects: 100% (6/6), done.
Writing objects: 100% (6/6), 715 bytes, done.
Total 6 (delta 4), reused 0 (delta 0)
To somehost:path/to/repo
   e1004df..bad8767  wpd -> wpd
 ! [rejected]        master -> master (non-fast-forward)
error: failed to push some refs to 'somehost:path/to/repo'
To prevent you from losing history, non-fast-forward updates were rejected
Merge the remote changes (e.g. 'git pull') before pushing again.  See the
'Note about fast-forwards' section of 'git push --help' for details.

The last time I encountered this, I did a "get checkout master; git
merge origin/master; git checkout wpd; git push" and that worked.  I
happen to know that master is a direct descendent of origin/master and
that, if I do this again, I will (once again) do a fast-forward merge
to bring master up to origin/master.

This may have been fixed in a more recent git (I'm using git 1.7.2.5
on a Debian 6 box and 1.7.4.1 on an RHEL 5 box).

There has got to be an easier way to fix this than checking out the
master branch, performing the fast-forward merge, and then switching
back to my working branch.

One way would be if there were some way to do a fast-forward merge on
a branch without actually checking out that branch.  Hence my
question.

Another way would be to remove the "master" branch from my config file.

Or perhaps I set up something wrong.

--wpd

Re: How to do a fast-forward merge without a checkout?

[Johannes Sixt]

Am 7/18/2011 16:18, schrieb Patrick Doyle:
> $ git push
...
> To somehost:path/to/repo
>    e1004df..bad8767  wpd -> wpd
>  ! [rejected]        master -> master (non-fast-forward)

[Context: Patrick works on the topic branch, but can't push it anymore
because the unrelated branch master was moved forward by someone else.]

After the obligatory 'git fetch', there are at least two ways to do this:

(1) The quick and unsafe way:

    $ git branch -f master origin/master

(2) The safer way:

    $ git push . origin/master:master

The second command is safer because it checks that origin/master is indeed
a direct descendent of master.

-- Hannes

Re: How to do a fast-forward merge without a checkout?

[Patrick Doyle]

On Mon, Jul 18, 2011 at 11:08 AM, Johannes Sixt <j.sixt@viscovery.net> wrote:
> Am 7/18/2011 16:18, schrieb Patrick Doyle:
>> $ git push
> ...
>> To somehost:path/to/repo
>>    e1004df..bad8767  wpd -> wpd
>>  ! [rejected]        master -> master (non-fast-forward)
>
> [Context: Patrick works on the topic branch, but can't push it anymore
> because the unrelated branch master was moved forward by someone else.]
>
> After the obligatory 'git fetch', there are at least two ways to do this:
>
> (1) The quick and unsafe way:
>
>    $ git branch -f master origin/master
>
> (2) The safer way:
>
>    $ git push . origin/master:master
>
> The second command is safer because it checks that origin/master is indeed
> a direct descendent of master.

I like it!  (#2) It's obscure as all get-out, as UNIX commands were
intended to be, does the job you need it to do in a manner that is
intuitive, provided you understand what it's doing, and if you miss
the dot (perhaps, hypothetically speaking of course, because you
thought it was a dust spec on your screen when you tried out the
command), you get a very obscure error message (errr, hypothetically
speaking of course).

Seriously... Thanks for the quick answers.  I'll tuck #2 into my bag
o' tricks.  In the mean time, I need to decide whether I really care
about my master branch or not.  I do care about origin/master, but I
do all my work on wpd and merge in changes from origin/master at
random points in time.

Thanks again.

--wpd

Re: How to do a fast-forward merge without a checkout?

[knittl]

On Mon, Jul 18, 2011 at 4:18 PM, Patrick Doyle <wpdster@gmail.com> wrote:
> […]
>
> $ git push
> […]
> To somehost:path/to/repo
>   e1004df..bad8767  wpd -> wpd
>  ! [rejected]        master -> master (non-fast-forward)
> error: failed to push some refs to 'somehost:path/to/repo'
> To prevent you from losing history, non-fast-forward updates were rejected
> Merge the remote changes (e.g. 'git pull') before pushing again.  See the
> 'Note about fast-forwards' section of 'git push --help' for details.
>

another way to avoid pushing the master branch is to explicitely name
the branch to push (wpd):

    $ git push origin wpd

cheers, daniel

-- 
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myFtPhp -- visit http://myftphp.sf.net -- v. 0.4.7 released!

Re: How to do a fast-forward merge without a checkout?

[Patrick Doyle]

On Mon, Jul 18, 2011 at 12:08 PM, knittl <knittl89@googlemail.com> wrote:
> On Mon, Jul 18, 2011 at 4:18 PM, Patrick Doyle <wpdster@gmail.com> wrote:
>> […]
>>
>> $ git push
>> […]
>> To somehost:path/to/repo
>>   e1004df..bad8767  wpd -> wpd
>>  ! [rejected]        master -> master (non-fast-forward)
>> error: failed to push some refs to 'somehost:path/to/repo'
>> To prevent you from losing history, non-fast-forward updates were rejected
>> Merge the remote changes (e.g. 'git pull') before pushing again.  See the
>> 'Note about fast-forwards' section of 'git push --help' for details.
>>
>
> another way to avoid pushing the master branch is to explicitely name
> the branch to push (wpd):
>
>    $ git push origin wpd
>
Thanks... I thought of that, but being basically lazy and not wanting
to have to type all of those extra characters every time I did a "git
push", I wanted to figure out a better way.

Seth Milliken posted a great explanation and alternative solution in a
comment to a blog post I found at
http://ken-blog.krugler.org/2010/02/25/git-failed-to-push-some-refs-the-multiple-branch-variant/.
 He suggested doing:

$ git config remote.origin.push HEAD

So that "git push" would default to only pushing the current branch.
I like that approach to my underlying problem as well.

But I stand in awe of Hanne's solution (#2) for it's brevity, the fact
that it does _exactly_ what I was asking about, and that the
capability is already baked into git.

--wpd

Re: How to do a fast-forward merge without a checkout?

[knittl]

On Mon, Jul 18, 2011 at 6:13 PM, Patrick Doyle <wpdster@gmail.com> wrote:
> On Mon, Jul 18, 2011 at 12:08 PM, knittl <knittl89@googlemail.com> wrote:
>> On Mon, Jul 18, 2011 at 4:18 PM, Patrick Doyle <wpdster@gmail.com> wrote:
>>> […]
>>>
>>> $ git push
>>> […]
>>> To somehost:path/to/repo
>>>   e1004df..bad8767  wpd -> wpd
>>>  ! [rejected]        master -> master (non-fast-forward)
>>> error: failed to push some refs to 'somehost:path/to/repo'
>>> To prevent you from losing history, non-fast-forward updates were rejected
>>> Merge the remote changes (e.g. 'git pull') before pushing again.  See the
>>> 'Note about fast-forwards' section of 'git push --help' for details.
>>>
>>
>> another way to avoid pushing the master branch is to explicitely name
>> the branch to push (wpd):
>>
>>    $ git push origin wpd
>>
> Thanks... I thought of that, but being basically lazy and not wanting
> to have to type all of those extra characters every time I did a "git
> push", I wanted to figure out a better way.

I can understand your laziness ;)

> Seth Milliken posted a great explanation and alternative solution in a
> comment to a blog post I found at
> http://ken-blog.krugler.org/2010/02/25/git-failed-to-push-some-refs-the-multiple-branch-variant/.
>  He suggested doing:
>
> $ git config remote.origin.push HEAD
>
> So that "git push" would default to only pushing the current branch.
> I like that approach to my underlying problem as well.

I prefer to use

    $ git config --global push.default current

which tells git to push the current branch to a branch of the same
name (for every repository). Another possible (and useful) value is
"upstream"/"tracking": push the current branch to it's upstream. Have
a look at the git config manpage for more options.

> But I stand in awe of Hanne's solution (#2) for it's brevity, the fact
> that it does _exactly_ what I was asking about, and that the
> capability is already baked into git.

Yup, pushing into the current repository to fast-forward branches
without checkout is quite neat indeed :)

Daniel

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