timedatectl status
journalctl
journalctl --utc
journalctl -b
journalctl --list-boots
journalctl -b -1
journalctl -u nginx.service --since today
journalctl _PID=8088
if -u www-data
journalctl _UID=33 --since today
journalctl -k => kernel
journalctl -k -b -5 => kenerl five boots ago
journalctl -p err -b => priority
0: emerg 1: alert 2: crit 3: err 4: warning 5: notice 6: info 7: debug
journalctl -b -u nginx -o json
journalctl -b -u nginx -o json-pretty
journalctl -n 20 20 last
journalctl -f => follow
journalctl --disk-usage