Undo without losing work · Lesson 12 of 15

Amend and reflog: rescue recent work

Repair the last commit and understand the local safety log of HEAD movements.

10 minutes2 games

Forgot a small file or wrote a poor message? git commit --amend replaces the latest commit with a new one containing the current staging area. Even with similar content its hash changes because it is a new object. Use it before pushing or with team agreement.

A—old B

amend

A—new B′

reflog records the move locally

Git

git init -q -b main
echo "code" > app.txt
git add app.txt
git commit -q -m "Ad app"
echo "docs" > README.md
git add README.md
git commit -q --amend -m "Add app and docs"
git log --format=%s

reflog records local positions visited by HEAD and branches after commits, resets and rebases. If a reset loses a commit name, find its hash in git reflog and create a rescue branch. The simulator explains this command; practise it in a real terminal.

Quick question

Does --amend edit the same commit object?

Exercise

Commit with the wrong subject Ad file, amend it to Add file, then print the subject.

Expected output: Add file

Git

git init -q -b main
echo "x" > file.txt
git add file.txt
git commit -q -m "Ad file"
git log --format=%s

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