Ignore generated files with .gitignore

Projects often generate files that should not become source history: build directories, local caches, editor files and environment-specific output.

A .gitignore file contains patterns for paths Git should normally leave untracked. It does not retroactively remove a file that is already tracked.

If a tracked file should remain on disk but leave the repository, remove it from the index with git rm --cached, then commit that change. For project-wide ignore rules, commit the .gitignore file itself.

Run this in a disposable practice repository unless the lesson explicitly says otherwise.

printf "node_modules/\n.env\n*.log\n" > .gitignore
git add .gitignore
git commit -m "Add project ignore rules"

git status

The rules ignore a dependency directory, a local environment file and log files when those paths are untracked. Keep secrets out of Git history entirely; ignoring a file only after a secret was committed does not erase that earlier history.

Your task: Create debug.log before and after adding *.log to .gitignore. Use git status to confirm it stays untracked. Then ask why a previously committed debug.log would behave differently.

Never rely on .gitignore as a secret-management system. If a credential has been committed, rotate/revoke it and follow an appropriate history-removal process if necessary.

Ignore generated files with .gitignore is complete when you can explain the state being changed before you run the command, not merely repeat the syntax.

Read further: official supporting documentation.