deploying_from_inside_a_unicorn.rb

    def run!
      pid = fork do
        exec_pid = fork do
          $0 = "heaven[#{Heaven.current_sha}] : executing deployment of #{application_name}"
          out_file = File.new(log, "w")

          STDIN.reopen("/dev/null")
          STDOUT.reopen(out_file)
          STDERR.reopen(out_file)

          execute
        end

        tail_pid = fork do
          $0 = "heaven[#{Heaven.current_sha}] : syslogging #{application_name}'s deploy number(#{number})"
          File::Tail::Logfile.open(log, :backward => 10) do |log|
            log.tail { |line| application.logger.info(line) }
          end
        end

        $0 = "heaven[#{Heaven.current_sha}] : reaper process, waiting for process(#{exec_pid})"

        Process.wait(exec_pid)
        status = $?.exitstatus
        Process.kill("TERM", tail_pid)
        exit(status)
      end
      Process.detach(pid)
    end