Automatically Rebase and Squash Git History From a Commit ID to HEAD from Branch to Master

Question

Is it possible to use git rebase to remove all of the history from a specific commit to the HEAD revision?

With git -i rebase, you have to count all of the commits in the git log and manually get squash of all of them except one commit before pushing the changes.

Is there a one-liner to do the following:

1. git rebase -i HEAD~4 for 4 commits
2. Within the text editor, squash everything and keep one pick (I think you have to pick at least one commit)
3. git fetch origin to update the references
4. git rebase origin/master to rebase the branch onto the master
5. git checkout master to switch to the master branch
6. git merge branch_name to merge the branch onto the master

Is it possible to do this with less steps or other flags?

Answer 1

Instead of git rebase -i you can run git rebase --soft <commit-id> to move HEAD to <commit-id> without changing the index or the working tree then git commit to create a new commit that contains all the changes since <commit-id>.

Answer 2

I believe what you're after is git commit --fixup. Thoughtbot's writeup on automating this might interest you.