Rewrite history

Goal#

Squash, reword and reorder commits on your own branch, and know when not to.

Rebase in one picture#

git rebase main takes your branch's commits and replays them, one by one, on top of main. The result has the same changes and new hashes. git rebase -i main does the same, but first opens a list where you decide what happens to each commit:

pick 1a2b3c4 Add bowl
pick 2b3c4d5 wip
pick 3c4d5e6 fix typo
pick 4d5e6f7 Add water
pick 5e6f7a8 wip again

Change the word at the start of a line to choose:

You can also move lines to reorder commits. Save and close the editor, and git does the rest. If anything goes wrong, git rebase --abort puts the branch back.

The hashes in the list above are only an example; yours will differ. Make sure git opens an editor you know: git config --global core.editor "code --wait" for VS Code, or nano.

Quest 09#

quest start 9

The kitchen branch has five messy commits. Tidy them into exactly two: one for bowl.txt, one for water.txt, with no "wip" or "fix" in any message. The files must end up exactly as they are now. Then quest check.

The rule from chapter 07, again#

Rewrite only commits you have not shared. Tidying your own branch before a pull request is good manners. Rebasing main after others pulled it is how teams lose an afternoon.

Check it works#

• git log --oneline main..kitchen shows two clean commits.
• quest check passes.

Exercise#

The same tidy-up has a second solution with no editor at all: git reset --soft main, then commit the files again in two steps. Start the quest over and do it that way. Which would you rather explain to a teammate?

More to try

• Make a commit called fixup! Add bowl with git commit --fixup <hash>, then run git rebase -i --autosquash main. Watch git pre-arrange the list for you.
• A rebase can hit conflicts, one commit at a time. Resolve, git add, then git rebase --continue.