How to detach a branch and reattach it to some different branch in Git

Question

I have a master and topic branch forked from it as shown below:

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

I want to detach this topic branch and attach it to my feature branch like shown below:

G---H---I---J feature
             \
              E---F topic

Here master and feature branches are present on both remote and local while the topic is only at my local. I want to push topic after reattaching it to feature.

Thanks

Answer 1

If feature contains B, then it's as simple as git rebase feature from the topic branch. If this is not the case, you'll need:

git rebase --onto feature B

The difference is because if B is not contained in feature, the rebase command won't know how far to wind back before replaying.

In general, git rebase --onto X Y means "replay all commits after Y on top of X". git rebase X is shorthand that first finds the common ancestor of HEAD and X (Z = git merge-base HEAD X), then replay all commits after Z on top of X.

Docs: https://git-scm.com/docs/git-rebase