tips

• exclude everything except directory foo/bar

/*
!/foo
/foo/*
!/foo/bar

• Show ignored files in git cache by .gitignore

git ls-files -i --exclude-from=/.gitignore

• ignore and remove file in git only (use --cached)

echo -e \!file >> /.gitignore
git ls-files -i --exclude-from=/.gitignore | xargs git rm -r --cached