Command execution with realtime feedback

executor.rb

        exit_code = Open3.popen3(env, cmd, opts) do |stdin, stdout, stderr, thread|
          stdin.close
          # Create a thread to read from each stream
          threads = [[:stdout, stdout], [:stderr, stderr]].collect do |method, stream|
            Thread.new do
              until (line = stream.gets).nil?
                callback.send(method, line)
              end
            end
          end
          
          pid = thread.pid
          yield(callback, pid) if block_given?
          
          # Don't exit until the external process is done
          threads.collect(&:join)
          thread.value
        end.exitstatus