commands.sh

cd ~/code/rails
railties/bin/rails new ~/code/hello --edge
cd ~/code/hello
echo "gem 'puma'" >> Gemfile
bundle
rails g controller hello index
# fill controller
puma
# separate tab
curl localhost:9292/hello/index
# separate tab
curl localhost:9292/hello/index # waits until first request finishes

hello_controller.rb

class HelloController < ApplicationController
  include ActionController::Live

  def index
    response.headers["Content-Type"] = "text/event-stream"
    10.times do |n|
      response.stream.write "data: #{n}...\n\n"
      sleep 2
    end
  ensure
    response.stream.close
  end
end