title: Macports register existing library built from source
body: <p>How can I tell MacPorts that I already have a certain library installed?</p>
  
  <p>For example, I built <code>libcurl</code> from scratch to get http2 protocol with <code>nghttp2</code>, <code>openssl</code> and <code>zlib</code>. I installed them to <code>/opt/local</code> -- same location as all MacPort libs on my system. However, Macports doesn't recognize that they are installed already.</p>
  
  <p>How can I tell MacPorts that these are already installed as well as their versions? Why? Because I'm trying to do:</p>
  
  <p><code>port install py35-pip</code> but it lists that <code>libz</code> and <code>openssl</code> are not installed.</p>