As systemd becomes the default method of handling services in all major Linux distributions, below are some quick and easy-to-remember commands that will make you look like a pro.

systemctl

  • check for all running units
    systemctl
    TIP: To show all units, including in-active ones:
    systemctl list-unit-files
  • Check for failed units
    systemctl --failed
  • Start, stop, restart units
    systemctl start postfix.service
    systemctl restart postfix.service
    systemctl stop postfix.service
  • Check status of a specific unit
    systemctl status mysqld.service
    TIP: Use -l for detailed status
  • Enable or disable services
    systemctl enable firewalld.service
    systemctl disable NetworkManager.service
    TIP: If you disable a service, and it still runs,
    systemctl mask NetworkManager.service
    Use ‘unmask’ to restore it
  • See if a specific unit is enabled
    systemctl is-enabled iptables.service
  • Create a snapshot – useful for testing various targets
    systemctl snapshot example.snapshot
    TIP: To activate it:
    systemctl isolate example.snapshot
  • Reboot/poweroff/suspend your machine
    systemctl reboot
    systemctl poweroff
    systemctl suspend
  • Change current target – i.e. runlevel
    systemctl isolate graphical.target
  • To list current target
    systemctl list-units --type=target

systemd

  • See which units take a long time to start during boot up
    systemd-analyze blame
    TIP: You can plot the boot up using:
    systemd-analyze plot
  • See when a unit started and how long it took
    systemd-analyze critical-chain

journalctl

  • Create a running log like ‘tail -f /var/log/messages’
    journalctl -f -o cat --no-pager
  • Running log for a specific unit
    journalctl -f -o cat --no-pager -u httpd.service
  • See boot messages – like ‘dmesg’
    journalctl -b

Manage remote systems:
systemctl status sshd -H root@1.2.3.4

For detailed instructions on these and more commands, man as always is your best friend.