How do I edit a commit with interactive rebase as uncommited?

Question

I would like to use an interactive rebase to edit a previous commit, but when I enter the edit mode for that commit all the files have been committed.

I know I can make changes and amend the commit but I want all the changes uncommitted initially (staged or otherwise) so I can edit it as if it was moments before it was originally committed. Is this possible?

Answer 1

Imagine git rebase --interactive gives you this list:

pick 3d15626 first
pick 7911b8b second
pick 60d94b4 third

and you now want to edit the second commit in its un-committed state. For this change its line like the this:

pick 3d15626 first
exec git cherry-pick --no-commit 7911b8b && false
pick 60d94b4 third

What this line does:

• instead of picking the commit normally git cherry-pick is executed
• git cherry-pick will apply the "second" commit (note the same commit hash used) to the index and the working tree, preload the commit message but not commit (--no-commit)
• && false ensures that the executed command "fails" by returning a failing exit code. This forces git rebase to break after this line to let you "fix" the problem, i.e. you can now edit the commit
• after you are done editing you can git commit it again. The editor will automatically contain the original commit message thanks to git cherry-pick
• after you committed the commit and the index is clean again you can continue with git rebase --continue

Answer 2

You can at least reset to the previous commit, add everything and commit: you will then able to set again the commit message.

 git reset @~
 git add .
 git commit --interactive

Or actually just git commit, since you already added what you wanted.
That would still open an editor for you to enter the commit message again.