7. Undoing Things — Git's Safety Net

❌ Undo an Uncommitted Change

Discard changes in a file (revert to last committed version). WARNING: This permanently deletes uncommitted changes.

Discard ALL uncommitted changes in the working directory:

Remove a file from staging (unstage it, keep the changes):

🔧 Amend the Last Commit

Fix a typo in the last commit message:

Add a forgotten file to the last commit. The --no-edit flag keeps the original commit message:

IMPORTANT: Only amend commits that haven't been pushed yet! Amending a pushed commit rewrites history and causes problems for teammates.

⏪ git revert — The Safe Undo for Shared History

git revert creates a NEW commit that undoes a previous one. This is the safe way to undo on branches that have been pushed. First find the commit hash to undo:

Revert (undo) a specific commit. Git creates a new commit (e.g., "Revert 'Add broken feature'"). The history is preserved — the undo is itself a commit. Now push the revert to update the remote:

⚠️ git reset — The Powerful (Dangerous) Undo

git reset moves the branch pointer backward in history. Use ONLY on local branches that have NOT been pushed.

--soft: undo the commit, keep changes staged:

--mixed (default): undo the commit, keep changes unstaged:

--hard: undo the commit AND delete all changes. WARNING: --hard permanently deletes uncommitted work.

HEAD~1 means "one commit before HEAD". HEAD~3 means "three commits before HEAD".

GOLDEN RULE: Never reset commits that have been pushed to a shared branch. It rewrites history and will conflict with your teammates' local copies.

🔎 git reflog — Your Last Resort

git reflog records EVERY move of HEAD — even reset and deleted branches. It is the recovery tool for "I've done something terrible".

Recover a commit you accidentally reset, or restore your branch to that point: