def stop_bg(pid)
      file = pidfile(pid)
      if File.exist? file
        pid = File.read file
        File.delete file
        run "kill -s TERM #{pid}"
      else
        say "!txtred!PID file not found." unless Runfile.quiet
      end
    end
def stop_bg(pid)
      file = pidfile(pid)
      if File.exist? file
        pid = File.read file
        File.delete file
        run "kill -s TERM #{pid}"
      else
        say "!txtred!PID file not found." unless Runfile.quiet
      end
    end
Stop a command started with 'run_bg'. Provide the name of he pid file you
 used in 'run_bg'