World 2: Undo Magic

Undo safely with revert

You will learn: how to undo a shared commit without rewriting history.

The problem

Two commits ago, you made the heading blink. Everyone hates it. Your team already has that commit.

Watch

adds a new commit that does the opposite. The bad commit stays in history. Nothing is erased.

Try it

Tap the commit that made the heading blink.

Tap the bad commit.

Predict

You revert “Make heading blink”. Is your day 2 entry still there?

Try it

Now revert the blink commit in the terminal.

Hint

HEAD~1 is the commit just before the newest one.

Check

Your bad commit is already on GitHub. Which undo do you pick?

You did it!

You can now undo a shared commit without breaking anyone’s history.

Go deeper (optional)

In real Git, git revert opens your editor with a ready message. Save and close it. --no-edit skips the editor. Did later commits change the same lines? Then you get a conflict. Conflicts come in World 3.

~/diary $ git revert --no-edit HEAD~1[main bd92bf2] Revert "Make heading blink" 1 file changed, 1 deletion(-)~/diary $ git log --onelinebd92bf2 (HEAD -> main) Revert "Make heading blink"839ee20 Add day 2 entryac9bec3 Make heading blink270a76e Add stylea8feb63 Add day 1 page6d3a9b1 Add README