title: log_format in nginx.conf being ignored
body: <p>Total NGINX beginner here.</p>
  
  <p>My logs currently look like:</p>
  
  <blockquote>
    <p>92.21.236.47 - - [08/Jan/2017:00:48:10 +0000] "GET / HTTP/1.1" 200 148 "-" "Mozilla/5.0 (Windows NT 10.0; WOW64; rv:50.0) Gecko/20100101 Firefox/50.0"</p>
  </blockquote>
  
  <p>When I add the following line in the default /etc/nginx/nginx.conf</p>
  
  <pre><code>log_format main '$remote_addr - $remote_user xxx[$time_local]xxx '
                  '"$request" $status $body_bytes_sent '
                  '"$http_referer" "$http_user_agent"';
  
  access_log /var/log/nginx/access.log; 
  error_log /var/log/nginx/error.log;
  </code></pre>
  
  <p>(the access_log and error_log lines already exist in the default config, I have put these here solely for context).</p>
  
  <p>I then restart NGINX with:</p>
  
  <pre><code>systemctl restart nginx
  </code></pre>
  
  <p>I now expect my logs to change and in particular to show the xxx literal values used .. xxx[$time_local]xxx .. but my change makes no difference.</p>
  
  <p>If I change <strong>log_format main</strong> to <strong>log_format combined</strong> then the server won't restart.</p>