Replaying a set of changes on a specific branch

git rebase --onto somewhere base extension

Take the extension branch, figure out where it diverged from the base branch, and replay these patches in the extension branch as if it was based off the somewhere branch instead.

With a history like this,

c1 - c2 - c3 (master)
      \
        c4 - c5 - c6 (server)
              \
                c7 - c8 (client)

running

git rebase --onto master server client

would result in:

          (master)
c1 - c2 - c3 - c7' - c8' (client)
      \
        c4 - c5 - c6 (server)

NB: if the rebase of extension on base would not result in any commit (extension and base pointing to the same commit), no commits will be added onto somewhere.

Say a fix has been developed on the branch fix, and that the changes have been incorporated in the master branch in some manner (merge, cherry-pick, etc). Now we want to backport the fix to a previous point in the history, v1.

(v1)           (master)            (v1)           (master)
c1 - c2 - c3 - c4'                 c1 - c2 - c3 - c5
      \                   OR             \      /
        c4 (fix)                           c4 (fix)

In this case, running

git rebase --onto v1 master fix

will only move fix to v1.

(v1, fix)           (master)
c1 - c2 - c3 - c4'

The changes in c4 will not be replayed on top of c1, because replaying fix on master would not include c4, since it's already part of master.

Source:

• Pro Git
• experience
• learning the hard way