code: func ExecCmdDir(dir, cmdName string, args ...string) (string, string, error) {
  	bufOut, bufErr, err := ExecCmdDirBytes(dir, cmdName, args...)
  	return string(bufOut), string(bufErr), err
  }
docs: // ExecCmdDir executes system command in given directory
  // and return stdout, stderr in string type, along with possible error.