9. Undoing Things

This is where most developers get stuck. Know the right tool for each situation.

Before committing

# Unstage a file (keep working dir changes)
git restore --staged file.txt

# Discard working dir changes (PERMANENT — can't recover)
git restore file.txt
git restore .            # discard ALL working dir changes

# Undo all working dir changes back to last commit
git checkout -- .        # older syntax (same effect)

After committing

# Amend the last commit (local only — don't amend pushed commits)
git commit --amend -m "corrected message"

# Undo last commit, keep changes staged
git reset --soft HEAD~1

# Undo last commit, keep changes unstaged
git reset HEAD~1         # (default: --mixed)

# Undo last N commits, keep working dir intact
git reset HEAD~3

# Nuclear: undo last commit, discard all changes (DESTRUCTIVE)
git reset --hard HEAD~1

# Safe undo for pushed commits: create a reverting commit
git revert HEAD          # reverts last commit, makes new commit
git revert a1b2c3        # revert specific commit
git revert HEAD~3..HEAD  # revert a range

Reset modes at a glance

Mode	Staging	Working Dir	Use when
--soft	keeps staged	untouched	Re-commit with changes
--mixed	unstages	untouched	Rework what to include
--hard	cleared	cleared	Truly discard everything

Restore a deleted file

git checkout HEAD -- deleted-file.txt     # restore from last commit
git show HEAD:path/to/file > recovered.txt  # extract to a new file

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