``` map $time_iso8601 $logdate { '~^(?<ymd>\d{4}-\d{2}-\d{2})' $ymd; default 'date-not-found'; } map $time_iso8601 $logtime { '~^(?<ymd>\d{4}-\d{2}-\d{2})T(?<his>\d{2}:\d{2}:\d{2})' '$ymd $his'; default $time_iso8601; } log_format main '[$logtime] [$remote_addr] [$remote_user] [$request] ' '[$status] [$body_bytes_sent] [$http_referer] ' '[$http_user_agent] [$http_x_forwarded_for]'; access_log /var/log/nginx/access-${logdate}.log main; ```