Linux, Nginx, MySQL, and PHP (LEMP)

systemctl status nginx mysql php7.2-fpm

systemctl restart nginx mysql php7.2-fpm
(no output)

cat /var/log/mysql/error.log | grep ERROR
cat /var/log/php7.2-fpm.log | egrep "WARNING|NOTICE|ERROR|server reached pm.max_children setting"
journalctl -r | egrep -i "error|critical|Killed process|segfault"

tail -f /var/log/php*-fpm.log 
tail -f /var/log/nginx/error.log
tail -f /var/log/mysql/error.log

See also

• MariaDB logs, /var/log/mysql/error.log
• Nginx logs, /var/log/nginx/error.log
• LAMP, LEMP