The solution mentioned in “.gitignore file not ignoring” is a bit extreme, but should work:
# rm all files
git rm -r --cached .
# add all files as per new .gitignore
git add .
# now, commit for new .gitignore to apply
git commit -m ".gitignore is now working"
(make sure to commit first your changes you want to keep, to avoid any incident as jball037 comments below.
The --cached option will keep your files untouched on your disk though.)
You also have other more fine-grained solution in the blog post “Making Git ignore already-tracked files”:
git rm --cached `git ls-files -i --exclude-standard`
Bassim suggests in his edit:
Files with space in their paths
In case you get an error message like
fatal: path spec '...' did not match any files, there might be files with spaces in their path.You can remove all other files with option
--ignore-unmatch:
git rm --cached --ignore-unmatch `git ls-files -i --exclude-standard`
but unmatched files will remain in your repository and will have to be removed explicitly by enclosing their path with double quotes:
git rm --cached "<path.to.remaining.file>"