Let’s consider a relatable (albeit slightly exaggerated) scenario.
It’s been a long, chaotic day—packed with code reviews, endless brainstorming sessions, and a CI pipeline that seems determined to sabotage your simple one-line bug fix for an entire week. If only this were fiction.

Amidst the madness, you finally get a notification—someone reviewed your PR. But to your dismay, it’s just one comment. And not even a meaningful one. It’s about a rogue change in a shared config file—env, config.js, playwright.config.js, or the dreaded package.json—one of those files that sneaked into your commit unnoticed.

🥁 Enters update-index

The git update-index command updates the index - staging area - entries for one or more files. In simpler terms, it helps you git ignore files valid only to your local index - unlike .gitignore, which ignores files for every user commiting to that repo.

🧠 What this does:

• 🛑 Git stops tracking changes to package.json (locally).
• ⏳ You can still pull updates from the repo without needing to stash your changes.
• 🙌 Your local changes won’t show up in git status, and you won’t accidentally commit them.
• 🛟 Persists across branch changes on your local.

There’s an alternative flag called --assume-unchanged which achieves a similar function, they defer slightly in how they work in git internals.

While in 90% of your use cases, you’ll make do with skip-worktree, here’s a general brief of they differ:

📝 Note. If the file shouldn’t be tracked at all (for everyone), use .gitignore instead.