Why this article?

There may be many good articles about Git rebase, but I failed to find one that covers everything I want it to. Plus I need a draft for the Japanese version of this article, so here it is.

Forenote

I am not 100% sure that all information is accurate. This article is mostly based on how I commonly use this feature of Git, and I try to ensure that the information is accurate, but there are no guarantees.

Features branches

This introduction assumes the use of feature braanches, where force-push is acceptable.

To update a local feature branch that has been affected by force-push, try

$ git pull --rebase origin $BRANCH

If it is alright to discard local changes on the branch, try

$ git reset --hard origin/$BRANCH

What is Git rebase?

when we run git rebase main on branch develop, we get

What is Git interactive rebase?

When we run git rebase -i main instead, we get git like below:

pick 0000003 Commit message for commit 3
pick 0000004 Commit message for commit 4
pick 0000005 Commit message for commit 5

We can edit this file, save and quit the editor. Then the rebase will begin.

Basic commands: continue and abort

git rebase --continue allows one to continue a rebase, and git rebase --abort allows one to abort one.

Squash

If we edit the rebase todo to as follows,

pick 0000003 Commit message for commit 3
squash 0000004 Commit message for commit 4
pick 0000005 Commit message for commit 5

Then we will get two commits: one commit consisting of changes from 0000003 and 0000004, and another commit consisting of changes from 0000005. You will also be prompted to edit the commit message for the commit consisting of both changes from 0000003 and 0000004.

Edit

If we edit the rebase todo to as follows,

pick 0000003 Commit message for commit 3
edit 0000004 Commit message for commit 4
pick 0000005 Commit message for commit 5

Then the rebase will pause after the commit 0000003 and 0000004. The state will be as shown below (assuming that no conflicts occur during the rebase of 0000003 and 0000004):

Git commands can then be issued, including git commit --amend after editing some files. Run git rebase --continue to continue the rebase.

Drop

If we edit the rebase todo to as follows,

pick 0000003 Commit message for commit 3
drop 0000004 Commit message for commit 4
pick 0000005 Commit message for commit 5

then when the reabse completes the history will be as follows (notice that the commit 0000004 is gone):

Rearranging commits

If we edit the rebase todo to as follows,

pick 0000005 Commit message for commit 5
pick 0000004 Commit message for commit 4
pick 0000003 Commit message for commit 3

then when the reabse completes the history will be as follows (notice the order of the commits):

Common patterns

Catching up with the main branch

git checkout feature followed by git rebase main should do most of the time.

Catching up with the main branch (with stacked PRs)

The following instructions should update all branch

$ git checkout main
$ git checkout develop-1
$ git rebase -
$ git checkout develop-2
$ git rebase -

The final result will be as follows:

Updating stacked PRs with changed commits

Here commit 1000004 is the changed version of commit 0000004. 0000005-1 and 0000005-2 are the same commits.

Run the commands as follows:

$ git checkout main
$ git checkout develop-1
$ git rebase main
$ git checkout develop-2
$ git rebase -i develop-1

drop 0000004 Commit 4, revision 1
drop 0000005-2 Commit 5
pick 0000006 Commit 6
pick 0000007 Commit 7

The result will be as follows: