From Fedora Project Wiki

Revision as of 23:56, 30 August 2016 by Markuss (talk | contribs) (2 typos)

systemd is a system and service manager for Linux, compatible with SysV and LSB init scripts. systemd provides aggressive parallelization capabilities, uses socket and D-Bus activation for starting services, offers on-demand starting of daemons, keeps track of processes using Linux cgroups, supports snapshotting and restoring of the system state, maintains mount and automount points and implements an elaborate transactional dependency-based service control logic. It can work as a drop-in replacement for sysvinit. For more information, watch the video at

For system administrators
System administrators can visit this page, to understand how to use the native systemctl calls that replace their old workflow in SysVinit. Note that the service and chkconfig commands will continue to work as expected in the systemd world.

Why systemd?

systemd documentation

systemd has very comprehensive documentation. Refer to

Boot Kernel Command Line

On boot systemd activates (by default), the target unit whose job is to activate services and other units by pulling them in via dependencies.

To override the unit to activate, systemd parses its own kernel command line arguments via the systemd.unit= command line option. This may be used to temporarily boot into a different boot unit. The classical run-levels are replaced as following: is a special target unit for setting up the base system and a rescue shell (similar to run level 1);, is very similar to passing init=/bin/sh but with the option to boot the full system from there; for setting up a non-graphical multi-user system; for setting up a graphical login screen.

For details about these special systemd boot units, view the man systemd.special page. it scripts

What is the tool to manage services with systemd?

systemctl is the primary tool to use. It combines the functionality of both service and chkconfig into a single tool that you can use for instance to enable/disable services permanently or only for the current session.

list all running services etc:


Refer to man systemctl for more details. systemd-cgls lists the running process in a tree format. It can recursively show the content of any given control group. Refer to man systemd-cgls for more details.

How do I start/stop or enable/disable services?

Activates a service immediately:

  systemctl start foo 

Deactivates a service immediately:

  systemctl stop foo 

Restarts a service:

 systemctl restart foo 

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

 systemctl status foo 

Enables a service to be started on bootup:

 systemctl enable foo 

Disables a service to not start during bootup:

 systemctl disable foo 

Prevent a service from starting dynamically or even manually unless unmasked:

 systemctl mask foo 

Check whether a service is already enabled or not:

 systemctl is-enabled foo

Refer to man systemctl for more details.

How do I change the target (runlevel)?

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

Run level 3 is emulated by Run level 5 is emulated by is a symbolic link to and is a symbolic link to

You can switch to 'runlevel 3' by running

 systemctl isolate 

You can switch to 'runlevel 5' by running

 systemctl isolate 

How do I change the default target?

 systemctl set-default <name of target>.target is the default. You might want for the equivalent of non graphical (runlevel 3) from sysv init. The full list of targets can be accessed via systemctl list-units --type=target

systemd does not use /etc/inittab file.

How do I know the current target?

 systemctl get-default 

How to power off the machine?

You can use


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.

Does service command work with systemd?

Yes. It has been modified to call systemctl automatically when dealing with systemd service files. So either of the following commands does the same thing

 systemctl stop NetworkManager 


 service NetworkManager stop 

Does chkconfig command work with systemd?

Yes, for turning on/off services, compatibility has been provided both ways. chkconfig has been modified to call systemctl when dealing with systemd service files. Also systemctl automatically calls chkconfig when dealing with a traditional sysv init file.

So either of the following commands does the same thing

 systemctl disable NetworkManager 


 chkconfig NetworkManager off 

chkconfig --list doesn't list systemd services, only Sys V services. The output of chkconfig takes note of this, along with supplying additional information.

Does system-config-services work with systemd?

Yes. It does.

How do I change the number of gettys running by default?

The simplest way is to edit /etc/systemd/logind.conf (man page):


This setting will take effect after reboot.

Alternatively, which open the login prompt can be enabled and started individually.

To add another getty:

systemctl enable getty@tty8
systemctl start getty@tty8

To remove a getty:

systemctl disable getty@tty8
systemctl stop getty@tty8

systemd does not use /etc/inittab file.

How do I set automatic login on a virtual console terminal?

First create a new service similar to getty@.service:

# cp /lib/systemd/system/getty@.service \
# ln -s /etc/systemd/system/autologin@.service \

then edit ExecStart, Restart and Alias values, like this:

ExecStart=-/sbin/mingetty --autologin USERNAME %I

and finally reload daemon and start the service:

systemctl daemon-reload
systemctl start getty@tty8.service

Note that if you exit tty8 session, you wont be able to use it until next reboot or manual start by systemctl, except if you leave Restart as ‘always’, but I highly recommend to avoid this according to security reasons.

How do I customize a unit file/ add a custom unit file?

The best way to customize unit files is to add /etc/systemd/system/foobar.service.d/*.conf where foobar.service is the name of the service you want to customize. If a directory doesn't already exist, create one and drop a conf file with the settings you want to override. For example,



Refer to man systemd.unit page for more details.

Don't forget to reload systemd daemon using systemctl daemon-reload and systemctl restart foobar after editing a unit file where foobar is the name of the unit. Also note that you can systemd-delta to list the unit files which have been customized and also the precise differences

Special care must be taken when overriding options which can be set muliple times (ExecStart, ExecStartPre, ExecStartPost are a common example). Assigning some value to the option appends to the existing list, while assiging the empty value resets the list.

For example, let's say we have a service file like this:

ExecStart=/bin/echo execstart1
ExecStart=/bin/echo execstart2
ExecStartPost=/bin/echo post1
ExecStartPost=/bin/echo post2

When started, this service will print


The same rules apply to snippets in .d directories. This means that snippets which override ExecStart and similar settings, often should start with the empty assignment ExecStart=, followed by the new setting.

How do I debug systemd issues?

Refer to How_to_debug_Systemd_problems

Man pages

systemd comes with extensive documentation including several man pages.

On the web: list of all systemd man pages, index of all settings.