code: def readCmd(cls, cmd):
          
          args = shlex.split(cmd)
          proc = subprocess.Popen(args, stdout=subprocess.PIPE)
          (proc_stdout, proc_stderr) = proc.communicate(input=None)  # proc_stdin
          return proc_stdout.decode()
docs: run command and return the str format stdout
  
          Args:
              cmd: string
          Returns:
              str: what the command's echo