<span style="color:#323232;">DESCRIPTION
</span><span style="color:#323232;"> systemd is a system and service manager for Linux operating systems. When run as first process on boot
</span><span style="color:#323232;"> (as PID 1), it acts as init system that brings up and maintains userspace services. Separate instances
</span><span style="color:#323232;"> are started for logged-in users to start their services.
</span><span style="color:#323232;">
</span><span style="color:#323232;"> systemd is usually not invoked directly by the user, but is installed as the /sbin/init symlink and
</span><span style="color:#323232;"> started during early boot. The user manager instances are started automatically through the
</span><span style="color:#323232;"> [email protected](5) service.
</span><span style="color:#323232;">
</span><span style="color:#323232;"> For compatibility with SysV, if the binary is called as init and is not the first process on the
</span><span style="color:#323232;"> machine (PID is not 1), it will execute telinit and pass all command line arguments unmodified. That
</span><span style="color:#323232;"> means init and telinit are mostly equivalent when invoked from normal login sessions. See telinit(8)
</span><span style="color:#323232;"> for more information.
</span><span style="color:#323232;">
</span><span style="color:#323232;"> When run as a system instance, systemd interprets the configuration file system.conf and the files in
</span><span style="color:#323232;"> system.conf.d directories; when run as a user instance, systemd interprets the configuration file
</span><span style="color:#323232;"> user.conf and the files in user.conf.d directories. See systemd-system.conf(5) for more information.
</span>