How do I use 'git rebase -i' to rebase all changes in a branch?

Here's an example:

>git status
# On branch master
nothing to commit (working directory clean)
>git checkout -b test-branch
>vi test.c
>git add test.c
>git commit -m "modified test.c"
>vi README
>git add README
>git commit -m "modified README"

Now I want to do a 'git rebase -i' that will let me rebase all commits for this branch. Is there something like 'git rebase -i HEAD~MASTER' or similar. I figure I could do 'git rebase -i HEAD~2', but I really don't want to have to count how many commits have been made. I could also do 'git rebase -i sha1' but I don't want to comb through git log to find the first commit sha1. Any ideas?

Solution 1:

Ok, I'm asuming the branch is called "feature" and it was branched from "master".

There's this little git command called merge-base. It takes two commits and gives you the first common ancestor of both of those. So...

git merge-base feature master

...will give you the first common ancestor of those two commits. Guess what happens when you pass that commit to git rebase -i, like...

git rebase -i `git merge-base feature master`

Interactive rebase from the first common ancestor of both master and feature branch. Profit! ;)

Solution 2:

The issue with all provided solutions is, they do not allow you to rebase from the very first commit. If the first commit hash is XYZ and you do:

git rebase -i XYZ

You only rebase starting from the 2nd commit.

If you want to rebase from the first commit you do:

git rebase -i --root