Git · Lesson 6 of 6

Undoing changes & .gitignore

restore, revert, reset, amend and keeping files out of Git.

Different mistakes need different tools:

git restore file — throw away uncommitted edits to a file.
git restore --staged file — unstage, keeping your edits.
git commit --amend — fix the last commit's message or add a forgotten file (only before pushing).
git revert <commit> — make a new commit that undoes an old one. Safe for shared branches.
git reset --soft HEAD~1 — undo the last commit but keep its changes staged (local only).

Avoid git reset --hard and force-pushing on shared branches — they rewrite history others depend on.

.gitignore

A .gitignore file lists things Git should never track: node_modules/, .venv/, build output, logs and especially secrets such as .env files.

Example in the terminal

Run these on your own computer

$ git status
modified:   app.js

$ git restore app.js          # discard the edit

$ git log --oneline
a91e0c2 Remove salary filter by mistake
8b41d07 Add salary range filter

$ git revert a91e0c2
[main 5d7f310] Revert "Remove salary filter by mistake"

$ cat .gitignore
node_modules/
.venv/
.env
*.log

Lines starting with $ are commands you type; the rest is what Git prints. Names and URLs are examples.

Key points

restore = discard local edits.
revert = safe undo on shared history.
.gitignore keeps secrets and junk out of the repo.

Quick check

Which command safely undoes a commit that's already pushed to a shared branch?

git reset --hard git revert git commit --amend git push --force

Practice task

Add a .gitignore that ignores *.log and .env, create both files and confirm git status doesn't list them.

Interview corner

git reset vs git revert?

reset moves the branch pointer back (rewriting history) — fine for local work. revert creates a new commit that undoes changes — safe for shared branches.

You committed a password. What do you do?

Rotate the secret immediately (assume it's leaked), remove it from the code, add the file to .gitignore, and if needed purge it from history with a history-rewriting tool — then coordinate with the team.