Systemctl

systemctl command is used to control the systemd system and service manager.

Services configuration directory:

/etc/systemd/system/
   :sshd.service

Basic Usage

• systemctl status or systemctl status SERVICE_NAME
• systemctl stop SERVICE_NAME
• systemctl start SERVICE_NAME
• systemctl restart SERVICE_NAME
• systemctl reload SERVICE_NAME
• systemctl cat SERVICE_NAME or systemctl cat SERVICE_NAME.service
• systemctl list-timers
• systemctl list-units
  • systemctl list-units --all
  • systemctl list-units --failed
  • systemctl list-units --type=service
• List services:
  • systemctl list-unit-files
  • systemctl list-unit-files --state=enabled
• List services enabled: systemctl list-unit-files --state=enabled
• Show properties: systemctl show sshd.service
• View dependencies: systemctl list-dependencies sshd.service
• Creating new services in: /etc/systemd/system/ https://access.redhat.com/documentation/en-us/red_hat_enterprise_linux/7/html/system_administrators_guide/sect-managing_services_with_systemd-unit_files
• systemctl -t mount
• systemctl list-units -t mount
• systemctl enable FS_UNIT_NAME.mount
• sudo systemctl enable --now snapd.socket
• systemctl disable SERVICE_NAME
• systemctl --type swap
• systemctl daemon-reload

Activities

Basic

• Read systemd Cheat-sheet: https://www.linuxtrainingacademy.com/systemd-cheat-sheet/
• Enable or disable Automatic updates in your Ubuntu machine

Advanced

• Read Why are reboot, shutdown and poweroff symlinks to systemctl?: https://unix.stackexchange.com/questions/77029/why-are-reboot-shutdown-and-poweroff-symlinks-to-systemctl/77030#77030
• Create a service that restart on-failure. https://superuser.com/questions/507576/how-to-automatically-restart-a-linux-background-process-if-it-fails

See also

• Systemd: systemctl, systemd-journald, journalctl systemd-cat, systemd-logind, systemd-networkd:networkctl, systemd-timesyncd, systemd-resolved, systemd-udevd , Systemd-logind: loginctl, hostnamectl, udevadm, systemd-run, portablectl, systemd-nspawn, systemd resource management, Timer (systemd), systemd logs, /etc/systemd/, systemd services, systemd-mount, /run/systemd/, .service, /usr/lib/systemd/, /usr/lib/systemd/system/, /usr/lib/systemd/system/systemd-resolved.service, /lib/systemd/, machinectl, systemd-oomd, systemd-analyze
• Systemd services: systemctl [status | is-active | start | daemon-reload | stop | mask | reload | restart | reboot | enable | disable | cat], systemctl list-units, systemctl list-timers, systemctl --failed, systemctl get-default, systemctl --help, .service, .timer, .socket, systemctl restart elasticsearch.service, systemctl status apt-daily, systemctl status oscapd
• KVM services

https://www.freedesktop.org/software/systemd/man/systemctl.html

https://www.linuxtrainingacademy.com/systemd-cheat-sheet/

https://wiki.ubuntu.com/DebuggingSystemd