Finally, /sbin/init is run by the Linux kernel, once /linuxrc is complete. /sbin/init scans through the /etc/inittab , performing actions as necessary...

The /etc/init.d/rcS file is run by init, and loads the startup elements for LRP. The rcS file is specified in /etc/inittab in a line like: si::sysinit:/etc/init.d/rcS

The /etc/init.d/rc file is run for the appropriate run level (given as argument 1). The rc file is specified in /etc/inittab in lines like:

l0:0:wait:/etc/init.d/rc 0
l1:1:wait:/etc/init.d/rc 1
l2:2:wait:/etc/init.d/rc 2
l3:3:wait:/etc/init.d/rc 3
l4:4:wait:/etc/init.d/rc 4
l5:5:wait:/etc/init.d/rc 5
l6:6:wait:/etc/init.d/rc 6

/sbin/getty is normally run as part of the processing of init, providing a way to log into the system. getty takes care of both serial consoles and virtual consoles (though these could be two different kinds of gettys). getty is usually specified in lines like:

1:2345:respawn:/sbin/getty 38400 tty1
1:23:respawn:/sbin/getty 38400 tty2
1:23:respawn:/sbin/getty 38400 tty3
1:23:respawn:/sbin/getty 38400 tty4
1:23:respawn:/sbin/getty 38400 tty5