World 2: Undo Magic

Detached HEAD

You will learn: how to visit an old commit and get back safely.

The problem

You want to see your diary as it was on day 1. Just look, not change. How?

Watch

git switch --detach HEAD~2 visits an old commit. HEAD now points at a commit, not a branch. This is a .

Try it

Visit the commit “Add day 1 page”.

Hint

Type git switch --detach HEAD~2, then press Enter.

Watch

~/diary $ git checkout HEAD~2Note: switching to 'HEAD~2'.You are in 'detached HEAD' state. You can look around, make experimentalchanges and commit them, and you can discard any commits you make in thisstate without impacting any branches by switching back to a branch.If you want to create a new branch to retain commits you create, you maydo so (now or later) by using -c with the switch command. Example:  git switch -c <new-branch-name>Or undo this operation with:  git switch -Turn off this advice by setting config variable advice.detachedHead to falseHEAD is now at a8feb63 Add day 1 page

Old guides use git checkout with a commit. Same result, plus a long note. Don’t panic: it’s only advice.

Predict

You are on a detached HEAD. You commit, then switch to main. What happens to that commit?

Try it

You are visiting day 1. Get back to your branch.

Hint

Type git switch main, then press Enter.

You did it!

You can now visit old commits and come back safely.

Go deeper (optional)

git switch - jumps back to where you were before. Made commits while detached? Give them a branch before you leave, or they get left behind. Making branches comes in World 3. git checkout still works in Git 3.0, next to git switch.

~/diary $ git switch --detach HEAD~2HEAD is now at a8feb63 Add day 1 page~/diary $ git switch -Previous HEAD position was a8feb63 Add day 1 pageSwitched to branch 'main'