Useful SystemD commands

List all running services

# systemctl

Start/stop or enable/disable services

Activates a service immediately:

# systemctl start foo.service

Deactivates a service immediately:

# systemctl stop foo.service

Restarts a service:

# systemctl restart foo.service

Shows status of a service including whether it is running or not:

# systemctl status foo.service

Enables a service to be started on bootup:

# systemctl enable foo.service

Disables a service to not start during bootup:

# systemctl disable foo.service

Check whether a service is already enabled or not:

# systemctl is-enabled foo.service; echo $?

0 indicates that it is enabled. 1 indicates that it is disabled

How do I change the runlevel?

systemd has the concept of targets which is a more flexible replacement for runlevels in sysvinit.

Run level 3 is emulated by multi-user.target. Run level 5 is emulated by graphical.target. runlevel3.target is a symbolic link to multi-user.target and runlevel5.target is a symbolic link to graphical.target.

You can switch to ‘runlevel 3′ by running

# systemctl isolate multi-user.target (or) systemctl isolate runlevel3.target

You can switch to ‘runlevel 5′ by running

# systemctl isolate graphical.target (or) systemctl isolate runlevel5.target

How do I change the default runlevel?

systemd uses symlinks to point to the default runlevel. You have to delete the existing symlink first before creating a new one

# rm /etc/systemd/system/default.target

Switch to runlevel 3 by default

# ln -sf /lib/systemd/system/multi-user.target /etc/systemd/system/default.target

Switch to runlevel 5 by default

# ln -sf /lib/systemd/system/graphical.target /etc/systemd/system/default.target

systemd does not use /etc/inittab file.

List the current run level

runlevel command still works with systemd. You can continue using that however runlevels is a legacy concept in systemd and is emulated via ‘targets’ and multiple targets can be active at the same time. So the equivalent in systemd terms is

# systemctl list-units --type=target

Powering off the machine

You can use

# poweroff

Some more possibilities are: halt -p, init 0, shutdown -P now

Note that halt used to work the same as poweroff in previous Fedora releases, but systemd distinguishes between the two, so halt without parameters now does exactly what it says – it merely stops the system without turning it off.

 

Service vs. systemd

# service NetworkManager stop

(or)

# systemctl stop NetworkManager.service

Chkconfig vs. systemd

# chkconfig NetworkManager off

(or)

# systemctl disable NetworkManager.service

Readahead

systemd has a built-in readahead implementation is not enabled on upgrades. It should improve bootup speed but your mileage may vary depending on your hardware. To enable it:

# systemctl enable systemd-readahead-collect.service
# systemctl enable systemd-readahead-replay.service

SystemD cheatsheet

service foobar start systemctl start foobar.service Used to start a service (not reboot persistent)
service foobar stop systemctl stop foobar.service Used to stop a service (not reboot persistent)
service foobar restart systemctl restart foobar.service Used to stop and then start a service
service foobar reload systemctl reload foobar.service When supported, reloads the config file without interrupting pending operations.
service foobar condrestart systemctl condrestart foobar.service Restarts if the service is already running.
service foobar status systemctl status foobar.service Tells whether a service is currently running.
ls /etc/rc.d/init.d/ ls /lib/systemd/system/*.service /etc/systemd/system/*.service Used to list the services that can be started or stopped
chkconfig foobar on systemctl enable foobar.service Turn the service on, for start at next boot, or other trigger.
chkconfig foobar off systemctl disable foobar.service Turn the service off for the next reboot, or any other trigger.
chkconfig foobar systemctl is-enabled foobar.service Used to check whether a service is configured to start or not in the current environment.
chkconfig foobar –list ls /etc/systemd/system/*.wants/foobar.service Used to list what levels this service is configured on or off
chkconfig foobar –add Not needed, no equivalent.

References

fedoraproject.org/wiki/Systemd
fedoraproject.org/wiki/SysVinit_to_Systemd_Cheatsheet

Distribution Documentation

Gentoo
Arch
Ubuntu
Debian

// CrashMAG

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