How to display config true leaf's is default show

You need to implement something yourself as that feature is not available in a c-style CLI.

For example, if you are ok with using the confd_load command and have the user just provide a keypath, you could put something like this in your clispec

    <cmd name="show-all">
      <info>Show config and oper data</info>
      <help>Run confd_load -o -F c -p /your/path/here.</help>
      <callback>
        <exec>
          <osCommand>confd_load</osCommand>
          <args>-u $(user) -g $(groups) -o -F c</args>
          <options>
            <uid>confd</uid>
          </options>
        </exec>
      </callback>
      <params>
        <param>
          <info>&lt;path&gt;</info>
          <help>/path/to/show.</help>
          <flag>-p</flag>
        </param>
      </params>
    </cmd>