Why does .gitignore not work on a file I already committed?

.gitignore only affects untracked files. If a file was committed before you added it to .gitignore, Git keeps tracking it because it is already in the index. Run git rm --cached <file> to remove it from tracking, then commit — the ignore rule only takes effect after that.

What is the difference between .gitignore and git rm --cached?

.gitignore prevents untracked files from being added to Git in the future. git rm --cached removes a file Git is already tracking from the index without deleting it from disk — the step needed before .gitignore can take effect on that file.

How do I ignore .DS_Store and editor files in every project, not just one?

Create a global ignore file at ~/.gitignore_global, add patterns like .DS_Store and .vscode/, then run git config --global core.excludesfile ~/.gitignore_global so Git applies it across every repository on your machine.

Can .gitignore keep secrets like API keys out of my repository?

.gitignore prevents a secret file such as .env from being committed in the first place, but it cannot remove a secret that was already committed. If a key has already been pushed, rotate the credential and rewrite Git history — deleting the file in a new commit still leaves it recoverable from prior commits.

We’ve all seen it. You clone a repository, and there it is: a .DS_Store file, a __pycache__ folder, or worse—a file containing local API keys.

Committing these files is messy, unprofessional, and sometimes dangerous. The solution is simple but often misunderstood: the .gitignore file.

What Is .gitignore and Why It Matters

A .gitignore file is a plain-text configuration file that tells Git which files and directories to exclude from version control. It’s not just about keeping your repo tidy; it’s about security and collaboration. You don’t want to force your local editor settings or operating system junk on your teammates.

How to Create a .gitignore File in Git

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Global .gitignore: Excluding OS and Editor Files Across Every Repository

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Fixing “.gitignore Not Working”: Untracking Already-Committed Files with git rm –cached

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.gitignore Key Takeaways for Clean Git Repositories

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Stop Committing Garbage: A Masterclass in .gitignore

📚 This post is part of the "Git Survival Guide" series

What Is .gitignore and Why It Matters

How to Create a .gitignore File in Git

Global .gitignore: Excluding OS and Editor Files Across Every Repository

Fixing “.gitignore Not Working”: Untracking Already-Committed Files with git rm –cached

.gitignore Key Takeaways for Clean Git Repositories

References

Citation

Stop Committing Garbage: A Masterclass in .gitignore

📚 This post is part of the "Git Survival Guide" series

What Is .gitignore and Why It Matters

How to Create a .gitignore File in Git

Global .gitignore: Excluding OS and Editor Files Across Every Repository

Fixing “.gitignore Not Working”: Untracking Already-Committed Files with git rm –cached

.gitignore Key Takeaways for Clean Git Repositories

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References

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