Fix mistakes

Fix the last commit

You committed too early, with the wrong message.

git commit --amend -m "Add contributing guide"

You also forgot a file. Stage it and fold it into the same commit.

git add CODEOWNERS
git commit --amend --no-edit

--amend rewrites the last commit, so only use it before you push. Once a commit is on a shared branch, rewriting it forces everyone else to reconcile their history with yours.

Unstage a file

You staged a file you are not ready to commit.

git restore --staged notes.txt

The edit stays in your working tree. It is only no longer staged.

Throw away changes to a file

You want to discard an edit you have not staged.

git restore notes.txt

The edit is gone. Git does not keep a copy of changes you never staged or committed.

Undo the last commit, keep the work

You committed but want to change what is in the commit.

git reset --soft HEAD~1

--soft moves the branch pointer back one commit and leaves the changes staged, ready to commit again.

Undo a commit that is already pushed

The commit is already on the shared branch, so rewriting it is not an option.

git revert HEAD
git push

git revert adds a new commit that undoes the old one. History stays intact, which is why it is safe on a branch other people have already pulled.

Committed on the wrong branch

You meant to start a branch first, but committed on main instead.

git switch -c release-checklist
git switch main
git reset --hard origin/main
git switch release-checklist

Create the new branch before you reset main: it carries the commit forward, so resetting main afterward only removes the commit from main, not from anywhere.

Get back a lost commit

You reset too far and a commit seems gone.

git reflog

git reflog lists every commit HEAD has pointed to on this machine, including ones no branch points to anymore.

git reset --hard HEAD@{1}

Resolve a merge conflict

A teammate changed the same line of notes.txt you did, on main.

git merge origin/main

Git stops the merge and marks the conflict.

git status

On branch release-checklist
You have unmerged paths.
  (fix conflicts and run "git commit")

Unmerged paths:
  (use "git add <file>..." to mark resolution)
  both modified:   notes.txt

notes.txt now contains both versions, separated by marker lines:

<<<<<<< HEAD
Daily notes
=======
Weekly sync notes
>>>>>>> origin/main

Edit the file to keep what belongs, and delete the marker lines.

git add notes.txt
git commit

Git opens your editor with a prepared merge message; save and close it.

Push after rewriting your own branch

You already pushed release-checklist, then amended the last commit.

git push -u origin release-checklist
git commit --amend -m "Add release checklist with rollback steps"
git push --force-with-lease

--force-with-lease refuses to push if the remote branch moved since you last fetched it, so it only overwrites history you know about. Use it only on a branch nobody else has built on, never on main.

What’s next

What not to commitSecrets, build output, editor files, large binaries, and line endings: keep them out of the repository.

Git basics is licensed under CC BY 4.0: copy it, adapt it, keep the credit.