code: def _start_slave(src_id, cmdline, router):
      
      LOG.debug('_start_slave(%r, %r)', router, cmdline)
  
      proc = subprocess.Popen(
          cmdline,
          # SSH server always uses user's shell.
          shell=True,
          # SSH server always executes new commands in the user's HOME.
          cwd=os.path.expanduser('~'),
  
          stdin=subprocess.PIPE,
          stdout=subprocess.PIPE,
      )
  
      process = Process(
          router,
          proc.stdin.fileno(),
          proc.stdout.fileno(),
          proc,
      )
  
      return process.control_handle, process.stdin_handle
docs: This runs in the target context, it is invoked by _fakessh_main running in
      the fakessh context immediately after startup. It starts the slave process
      (the the point where it has a stdin_handle to target but not stdout_chan to
      write to), and waits for main to.