Engineering Craft › Version Control (Git)

.gitignore

Files Git should never track, like build output and .env.

Also known as: .gitignore file, gitignore, ignore file

A .gitignore file lists files and folders Git should pretend don’t exist, so they never show up as changes and don’t get committed by accident.

# dependencies and build output
node_modules/
dist/
__pycache__/

# secrets and local config
.env
*.local

# editor and OS noise
.DS_Store
.idea/

Put it in the repository root (commit it, so everyone shares the same rules).

What belongs in it

• Generated files: dependencies, build output, caches, compiled code.
• Secrets: .env files, private keys. Commit a .env.example with fake values so people know what to fill in.
• Machine-specific files: editor settings, OS files, logs.

Not in it: lockfiles like package-lock.json or poetry.lock. Those should be committed.

Patterns

The thing that trips everyone

.gitignore only affects files Git isn’t already tracking. If you committed .env before ignoring it, adding it to .gitignore does nothing. Stop tracking it (keeping your local copy) with:

git rm --cached .env
git commit -m "Stop tracking .env"

If it contained real secrets, they are still in history and must be treated as leaked: rotate them, and see removing secrets from history.

To ignore files across all your repos (like editor files), use a global ignore file, configured with core.excludesFile (see git config).