How RH Linux Boots :: rc
/etc/rc.d/rc is a conventional bash script, taking one paramenter:
the runlevel. It runs every time the runlevel changes.
The default RH version is about 100 lines long and containt the following
export runlevel as an environmental variable
save runlevel in /var/run/runlevel.dir
run kill scripts for the new runlevel
run start scripts for the new runlevel