Undoing in public

Amend and reset rewrite history: they take commits off your branch. That's fine for commits only you have. But once you've shared a commit, by pushing it or by letting a teammate pull it, other people's work is built on it. Take it off your branch and your history no longer matches theirs.

git revert undoes a commit without rewriting anything. It makes a new commit that does the opposite of the one you name. Lines the old commit added are removed, lines it removed come back, and files it created are deleted.

git revert HEAD

git writes the new commit's message for you: Revert "Add the banner", a blank line, and a line saying which commit it undoes. Like git commit --amend without -m, git revert opens that message in the edit pane first. Save it as it is, or change it, and git makes the commit.

To keep git's message without opening the edit pane, add --no-edit:

git revert --no-edit HEAD

Either way, git log --oneline then shows the bad commit and the commit that cancels it:

99af3e7 (HEAD -> main) Revert "Add the banner"
0067ace Add the banner
984ebf9 Style the heading
a0ec373 Add the home page

No commit left main. Your branch only moved forward, so everyone who pulls gets the revert as an ordinary new commit, and nothing breaks for them.

Revert any commit

Revert isn't limited to the last commit. Name any commit, and git undoes just that one. The commits after it stay as they are:

git revert HEAD~2

HEAD~2 is two commits before the one you're on. git log --oneline lists the commits newest first, which helps you count.

Every revert is a new commit, so the counting changes after each one. After git revert HEAD, the commit that was HEAD~1 is now HEAD~2. Check git log --oneline before each revert.

Undoing several commits

To undo several commits, revert them one at a time, newest first.

The order matters when a later commit changed the same lines as an earlier one. Revert the earlier one first, and git can't put its lines back, because they've changed since. It stops with a conflict.

If that happens, git revert --abort gives the revert up: your branch, the index and your files go back to how they were before git revert. git's message suggests it too, and git status says a revert is in progress until you abort it.

Reset or revert?

Compared	git reset	git revert
What it does	moves your branch back, so commits leave it	adds a new commit that undoes one
History	rewritten	kept, and only grows
Use it for	commits only you have	commits others may already have

A simple rule: if you've pushed it, revert it.

One thing you may see elsewhere: reverting a merge commit needs an extra option, -m, to say which side of the merge to keep. This course doesn't cover it.