how do I get page url in _master.tmpl

[mjangid]

Hello,

I am modifying default template and adding facebook link for each pages. can you please let me know how do achieve this?
code block for my template

    <article class="content wrap" id="_content" data-uid="{{uid}}">
    <div id="fb-root"></div>
    <script async defer crossorigin="anonymous"
      src="https://connect.facebook.net/en_US/sdk.js#xfbml=1&version=v7.0"></script>

        <div class="fb-like" data-href={{_appTitle}}  data-width="" data-layout="standard" data-action="like" data-size="small" data-share="true"></div>
        
        {{!body}}
    </article>