~^/A/shopby/(?<brand>[a-zA-Z]+) ~^/category/by-brand/$brand;

map $request_uri $new_uri {
  include /etc/nginx/urls.map;
}

server {
  rewrite_log on;
  error_log /var/log/nginx/error.log notice;

  if ($new_uri) {
     # return 200 $new_uri; for debugging
     rewrite $request_uri $new_uri permanent;
  }

 location / {
   root /a_root;
   index  index.html;
   try_files $uri $uri/ /index.html;
 }
}