title: How does nginx forward a header with a $ sign
body: <p>A Http Request has a header : <strong>$name</strong>,access nginx forward ,the header will lose ,but I need the header:$name,how can I config the nginx?</p>
  <p>example:</p>
  <pre><code>    location /api/ {
          proxy_pass         http://127.0.0.1:8081/;
          proxy_redirect     off;
          proxy_set_header   Host $host;
          proxy_set_header   $name $http_$name;
      }
  </code></pre>