brew install yoheimuta/protolint/protolint
Or brew tap yoheimuta/protolint
and then brew install protolint
.
Or install via URL (which will not receive updates):
brew install https://raw.githubusercontent.com/yoheimuta/homebrew-protolint/master/Formula/protolint.rb
brew help
, man brew
or check Homebrew's documentation.