systemd reads its configuration from files in the /etc/systemd directory. For example, the /etc/systemd/system.conf file controls how systemd handles system initialization.

The systemd daemon starts services during the boot process by reading the symbolic link /etc/systemd/system/default.target. The following example shows the value of /etc/systemd/system/default.target on a system configured to boot to a multiuser mode without a graphical user interface, a target called multi-user.target:

sudo ls -l /etc/systemd/system/default.target

 /etc/systemd/system/default.target -> /usr/lib/systemd/system/multi-user.target