Systemd

systemctl

Reference:
systemctl
$ systemctl status Show system status
$ systemctl list-units List running units
$ systemctl List running units
$ systemctl –failed List failed units
$ systemctl –all List running and inactive units
$ systemctl list-unit-files State of all installed units
$ systemctl status unit unit status
# systemctl start unit start
# systemctl stop unit stop
# systemctl restart unit restart the unit
# systemctl reload unit reload configuration
$ systemctl is-enabled unit enabled or disabled?
# systemctl enable unit enable to be started on boot
# systemctl disable unit disable not to be started on boot
# systemctl mask unit forbid starting the unit
# systemctl unmask unit unmask
# systemctl help unit help for the unit
# systemctl daemon-reload reload systemd
$ systemctl reboot reboot system
$ systemctl poweroff power-off
$ systemctl suspend suspend to memory
$ systemctl hibernate hibernate on disk
$ systemctl hybrid-sleep hibernate then sleep

journalctl

Reference:
journalctl
$ journalctl system log
$ journalctl -b journal since boot
$ journalctl -b 1 journal of previous boot
$ journalctl –since “2016-04-07 12:00:00” journal since some date
$ journalctl –since “2h ago” journal since some time
$ journalctl -u httpd –since=00:00 –until=9:30  
$ journalctl -u ntp journal for unit ntp
$ journalctl -f follow new messages
$ journalctl -e jump at end of journal
$ journalctl -n 1000 show at most 1000 entries
# usermod -a -G adm lennart allow user lennart to see logs