Troubleshooting Services With 'systemctl'
To view a description of all the active, loaded units, execute the systemctl command without any options or arguments:
systemctl
To see all the loaded, active, and inactive units and their description, run this command:
systemctl --all
To see all the unit files and their current status but no description, run this command:
systemctl list-unit-files
The grep
command filters the services by a search term, a helpful tactic to recall the exact name of a unit file without looking through a long list of names. Example:
systemctl list-unit-files | grep network
org.freedesktop.network1.busname static
dbus-org.freedesktop.network1.service enabled
systemd-networkd-wait-online.service enabled
systemd-networkd.service enabled
systemd-networkd.socket enabled
network-online.target static
network-pre.target static
network.target
For example, to list all the services that you can manage on Photon OS, you run the following command instead of ls /etc/rc.d/init.d/
:
systemctl list-unit-files --type=service
Similarly, to check whether the sshd
service is enabled, on Photon OS you run the following command instead of chkconfig sshd
:
systemctl is-enabled sshd
The chkconfig --list
command that shows which services are enabled for which runlevel on a SysVinit computer becomes substantially different on Photon OS because there are no runlevels, only targets:
ls /etc/systemd/system/*.wants
You can also display similar information with the following command:
systemctl list-unit-files --type=service
The following is list of some of the systemd commands that take the place of SysVinit
commands on Photon OS:
USE THIS SYSTEMD COMMAND INSTEAD OF THIS SYSVINIT COMMAND
systemctl start sshd service sshd start
systemctl stop sshd service sshd stop
systemctl restart sshd service sshd restart
systemctl reload sshd service sshd reload
systemctl condrestart sshd service sshd condrestart
systemctl status sshd service sshd status
systemctl enable sshd chkconfig sshd on
systemctl disable sshd chkconfig sshd off
systemctl daemon-reload chkconfig sshd --add