Nginx inclusive locations processing

https://habr.com/ru/company/oleg-bunin/blog/313666/

Short explanation afterwards

https://www.zagirov.name/post/nginx-config/

manual - http://nginx.org/ru/docs/http/ngx_http_core_module.html#location

Example: how to open phpinfo.php only for 1.2.3.4 address

        location ~ \.php$ {
                include snippets/fastcgi-php.conf;
                fastcgi_pass unix:/dev/shm/php-user72.sock;                
                deny all;
        }

        location ^~ /phpinfo {
                include snippets/fastcgi-php.conf;
                fastcgi_pass unix:/dev/shm/php-user72.sock;

                allow 1.2.3.4;
                deny all;
        }

Prefix location with ^~ disables first regexp location.