systemctl command is the central management tool for controlling the init system. It is widely used and has become the new standard for Linux distributions. Before you see some systemctl command examples, you can read more about systemd service and Units here
Let’s start with learning some systemctl commands examples.
To reboot the server
$ systemctl reboot
To shut down your computer
$ systemctl poweroff
To switch to rescue mode
$ systemctl rescue
List all the services on the server.
Many times you wish to see all the information about a service running on your server, then you can use the command below.
$ systemctl list-units --type=service
Output
Below is the expected output you should receive.
UNIT LOAD ACTIVE SUB DESCRIPTION auditd.service loaded active running Security Auditing Service chronyd.service loaded active running NTP client/server crond.service loaded active running Command Scheduler dbus.service loaded active running D-Bus System Message Bus firewalld.service loaded active running firewalld - dynamic firewall daemon [email protected] loaded active running Getty on tty1 ● kdump.service loaded failed failed Crash recovery kernel arming kmod-static-nodes.service loaded active exited Create list of required static device nodes for the current kernel lvm2-monitor.service loaded active exited Monitoring of LVM2 mirrors, snapshots etc. using dmeventd or progress polling network.service loaded active exited LSB: Bring up/down networking NetworkManager-wait-online.service loaded active exited Network Manager Wait Online
See active service
If you want to see only active service then you use the command below.
$ systemctl list-units --type=service --state=active
You can use running, stopped, enabled, disabled and failed for the service. Another example is to list the units.
$ systemctl list-units --type=service --state=failed UNIT LOAD ACTIVE SUB DESCRIPTION ● kdump.service loaded failed failed Crash recovery kernel arming
You can also list all the services, using the command below
$ systemctl list-units
See failed service
You can also list all failed units by the command.
$ systemctl list-units --failed
Starting a service
To start a service, you can use the command.
$ systemctl start {servicename}
Stopping a service
Similarly to stop the service you can use
$ systemctl stop {servicename}
Restarting a service
To restart the service you can use.
$ systemctl restart {servicename}
Enabling and disabling service
All the above commands, related to starting and stopping services were for the current runtime. However, in many situations, you don’t want to start the service automatically when the system boots. In that case, you will need to disable the service at the system boot.
To disable the service when the server boots
$ systemctl disable {servicename}
To make sure that the service starts every time when the server boots, you need to use the below command.
$ systemctl enable {serivcename}
To check the current status of the service you can use the command below.
$ systemctl is-enabled network.service
You should get a similar output as below.
network.service is not a native service, redirecting to /sbin/chkconfig. Executing /sbin/chkconfig network --level=5 disabled
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