Git: How to rebase to a specific commit?

Question

I'd like to rebase to a specific commit, not to a HEAD of the other branch:

A --- B --- C          master
 \
  \-- D                topic

to

A --- B --- C          master
       \
        \-- D          topic

instead of

A --- B --- C          master
             \
              \-- D    topic

How can I achieve that?

Answer 1

I've used a mixture of solutions described above:

$ git branch temp <specific sha1>
$ git rebase --onto temp master topic
$ git branch -d temp

I found it much easier to read and understand. The accepted solution lead me to a merge conflict (too lazy to fix by hand):

$ git rebase temp
First, rewinding head to replay your work on top of it...
Applying: <git comment>
Using index info to reconstruct a base tree...
M       pom.xml
.git/rebase-apply/patch:10: trailing whitespace.
    <some code>
.git/rebase-apply/patch:17: trailing whitespace.
        <some other code>
warning: 2 lines add whitespace errors.
Falling back to patching base and 3-way merge...
Auto-merging pom.xml
CONFLICT (content): Merge conflict in pom.xml
error: Failed to merge in the changes.
Patch failed at 0001 <git comment>
The copy of the patch that failed is found in: .git/rebase-apply/patch

When you have resolved this problem, run "git rebase --continue".
If you prefer to skip this patch, run "git rebase --skip" instead.
To check out the original branch and stop rebasing, run "git rebase --abort".

Answer 2

A simpler solution is git rebase <SHA1 of B> topic. This works irrespective of where your HEAD is.

We can confirm this behaviour from git rebase doc

<upstream> Upstream branch to compare against. May be any valid commit, not just an existing branch name. Defaults to the configured upstream for the current branch.

---

You might be thinking what will happen if I mention SHA1 of topic too in the above command ?

git rebase <SHA1 of B> <SHA1 of topic>

My little experiment shows that the command will execute but instead it will rebase a copy of topic branch there instead of rebasing topic branch. In short it does not work as we were expecting it to work. Hence don't use like this.

Answer 3

You can even take a direct approach:

git checkout topic
git rebase <commitB>

Answer 4

The comment by jsz above saved me tons of pain, so here's a step-by-step recipie based on it that I've been using to rebase/move any commit on top of any other commit:

1. Find a previous branching point of the branch to be rebased (moved) - call it old parent. In the example above that's A
2. Find commit on top of which you want to move the branch to - call it new parent. In the exampe that's B
3. You need to be on your branch (the one you move):
4. Apply your rebase: git rebase --onto <new parent> <old parent>

In the example above that's as simple as:

   git checkout topic
   git rebase --onto B A

Answer 5

There is another way of doing it or if you wish to move back to more than just one commit.

Here is a an example to move back to n number of commits:

git branch topic master~n

For the sake of this question, this can also be done:

git branch topic master~1

The command works perfectly on git version 2.7.4. Haven't tested it on any other version.

Answer 6

You can avoid using the --onto parameter by making a temp branch on the commit you like and then use rebase in it's simple form:

git branch temp master^
git checkout topic
git rebase temp
git branch -d temp