记录指定状态码的 nginx log

在 server 里配置，记录 403 的日志

server {
    server_name example.com;
    access_log /var/log/nginx_access_403.log combined;
    include block_inject.conf;
    location / {
        if ($status != "403") {
            access_log off;
        }
        #......
    }
}