RedHat RHEL/CentOS 7 Service Start Up Changes
RHEL/CentOS 7 Has A New Initialisation Daemon
The init daemon is the initialisation daemon first implemented in System V UNIX systems and has been around for over 40 years!
RedHat’s RHEL 7 and CentOS 7 introduces a replacement for init called systemd.
Startup & Run Levels
RHEL 6 (and CentOS 6) supported SysV init and Upstart with start and kill scripts created as links to scripts in /etc/rc.d/init.d scripts in the appropriate run level directory e.g. /etc/rc2.d.