How to ignore already added file in git

Gitignore is used to untrack files intentionally. It has specific pattern to describe which files to ignore. Good documentation regarding Gitignore has been given here :

Many time we have case where we mistakenly / intentionally adding files in Git tracking. And later we don't want to track it by any circumstances like database configuration or hiding credentials of production.

I mostly follow below steps to add those important files in gitignore and tell git not to track it anymore :

1) Remove file from git index by git rm --cached [file_name]

2) Commit changes git commit -m "intentionally removed file from git index"

3) Make entry of that file in ~/[project root dir]/.gitignore

4) Now edit the same file

5) Verify same file by git status to check it is not tracked

Hope that helps!!