# How do I undo a fast-forward merge safely?

3 messages from 2009-02-22 to 2009-02-24. Participants: Brent Goodrick, Jakub Narebski.
Thread: https://gitlist.dev/t/17958

## Brent Goodrick, 2009-02-22 19:15

Subject: How do I undo a fast-forward merge safely?
Message-ID: <e38bce640902221115o2dd1c63dv6f7acc374b48d418@mail.gmail.com>
URL: https://gitlist.dev/e/e38bce640902221115o2dd1c63dv6f7acc374b48d418%40mail.gmail.com

```
I had done a git merge --no-commit <source_branch> operation, but that
bit me because I mistakingly concluded that --no-commit would prevent
any type of automatic operation, but apparently a fast-forward
occurred.  I should have used the --no-ff option? How do I get my
target branch back to where it was before the bad merge?

I did make a backup of the entire repo before I started, so I do have
the plan-B option of replay my changes onto a copy of the backup repo.
  But, maintaining backup copies just so as to avoid getting bit each
time I forget to use the --no-ff option will be a non-starter, so I
would hope there are some safe commands I can use to go back to the
original.

git log -1 does not show the commit, but gitk does show a vertical red
line that I can only presume indicates the fast-forward.  How does
gitk determine that red line, while git-log does not?  Note that I
have not pulled into any other repo's yet, and won't until I can
rectify this issue.

Here was my bad git merge command line:

$ git merge --no-commit source_branch
Updating 7eb9a02..0c66ca1
Fast forward
<eliding list of files I want mixed in with lots of files I don't want>

So, what operations, rebase, reset, etc, do I need to do to get this
repo back to where it was right before the fast-forward?

Thanks,
Brent

```

## Jakub Narebski, 2009-02-22 19:54

Subject: Re: How do I undo a fast-forward merge safely?
Message-ID: <m3fxi6s0vu.fsf@localhost.localdomain>
URL: https://gitlist.dev/e/m3fxi6s0vu.fsf%40localhost.localdomain
In-Reply-To: <e38bce640902221115o2dd1c63dv6f7acc374b48d418@mail.gmail.com>

```
Brent Goodrick <bgoodr@gmail.com> writes:

> I had done a git merge --no-commit <source_branch> operation, but that
> bit me because I mistakingly concluded that --no-commit would prevent
> any type of automatic operation, but apparently a fast-forward
> occurred.  I should have used the --no-ff option? How do I get my
> target branch back to where it was before the bad merge?

[...]
> So, what operations, rebase, reset, etc, do I need to do to get this
> repo back to where it was right before the fast-forward?

Each 'large' operation sets ORIG_HEAD

  $ git reset --hard ORIG_HEAD

If you want to be more careful, examine reflog for HEAD, using either
"git reflog" or "git log -g", and you can reset to previous version of
HEAD (i.e. where current branch pointed to before 'git fetch') with

  $ git reset --hard HEAD@{1}

-- 
Jakub Narebski
Poland
ShadeHawk on #git

```

## Brent Goodrick, 2009-02-24 05:37

Subject: Re: How do I undo a fast-forward merge safely?
Message-ID: <e38bce640902232137s622410cv4506b8e0083bb468@mail.gmail.com>
URL: https://gitlist.dev/e/e38bce640902232137s622410cv4506b8e0083bb468%40mail.gmail.com
In-Reply-To: <m3fxi6s0vu.fsf@localhost.localdomain>

```
On Sun, Feb 22, 2009 at 11:54 AM, Jakub Narebski <jnareb@gmail.com> wrote:
> > So, what operations, rebase, reset, etc, do I need to do to get this
> > repo back to where it was right before the fast-forward?
>
> Each 'large' operation sets ORIG_HEAD
>
>  $ git reset --hard ORIG_HEAD
>

Thanks Jakub. "git reset --hard ORIG_HEAD" was what I went with and it
worked like a charm!

bg

```