systemd v/s init – Comparison

If you’re new to systemd, make sure that you first look here and then come back, so that you have an understanding about what I talked in this page. Below shows a quick comparison between systemd and init.


Category systemd init
System startup First process (PID:1) is system, thereby initializing the system and launching all the service.Also stores initial log messages. Init becomes parent or grandparent of all system processes after init is started. Doesn’t store initial log messages.
System Services Management Systemctl command replacing traditional service and chkconfig. Service and chkconfig commands for service start/stop and to identify run levels respectively.
Run level change Introducing concept of targets, representing a group of services that are started or stopped. A target inside another target is also possible. Runlevels to identify set of services that would start/stop when that runlevel was requested.
Default runlevel Default runlevel replaced by default targets, which is linked to multi-user target by default. Location is /etc/system/system/ Default runlevel set in /etc/inittab file.
Service location Services in the name <service>.service and stored in /lib/systemd/system and /etc/systemd/system Services stored as scripts in the location /etc/init.d and then linked to runlevel directories.
Config files Still files in /etc/sysconfig, but services can be modified by adding files to /etc/systemd directory. /etc/inittab file was used by the init process. Changes to the services were done in files in /etc/sysconfig directory.



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