• Red Hat unit files: /usr/lib/systemd/system
  • Customizations: /etc/systemd/system == runlevel 3 == runlevel 5


  • Prints the time spent in the kernel before userspace has been reached, the time spent in the initial RAM disk (initrd) before normal system userspace has been reached and the time normal system userspace took to initialize: systemd-analyze
  • Prints a list of all running units, ordered by the time they took to initialize: systemd-analyze blame
  • List known units: systemctl list-units
  • List all units installed on the system: systemctl list-unit-files
  • List all active services: systemctl list-units --type=service or systemctl -t service
  • View all of the services available (everything installed, running or not, similar with chkconfig): systemctl list-unit-files -t service
  • List all services: systemctl list-units --type service --all
  • Display the default target to boot into: systemctl get-default
  • Change default target: systemctl set-default and systemctl start if you do not want to reboot the workstation
  • Checks whether the specified unit files are enabled or not: systemctl is-enabled sshd
  • Enable the service at boot: systemctl enable httpd
  • Disable the service at boot: systemctl disable httpd
  • Check the service through SSH: systemctl status httpd -H root@<hostname>
  • Create a drop-in configuration file to extend the default httpd.service unit:
mkdir /etc/systemd/system/httpd.service.d
cd /etc/systemd/system/httpd.service.d
vim 50-httpd.conf
systemctl daemon-reload
systemctl status httpd


  • Display the configuration file: cat /etc/systemd/journald.conf
  • Show messages from system services and the kernel (default option): journalctl --system
  • Check logs specific to a particular service or executable: journalctl /usr/sbin/httpd or journalctl --unit httpd.service
  • Show only the most recent journal entries and continuously print new entries: journalctl -f
  • Filter output by message priorities or priority ranges: journalctl -p 3 or journalctl -p err
  • Start showing entries on or newer than the specified date: journalctl --since="2018-03-01 14:00:00" --until="2018-03-01 15:00:00"
  • Start showing entries on or newer than the specified date and a specific priority: journalctl -p err --since="2018-03-01 14:00:00" --until="2018-03-01 14:25:00"
debug (7)
info (6)
notice (5)
warning (4)
err (3)
crit (2)
alert (1)
emerg (0)