This it the toplevel configuration file for (System V style) init. It describes how the init process should set up the system in a certain run-level.
Each meaningful line (that is not commented or empty) consists of for fields that are separated by a colon (:).
id. Each id must be unique.
runlevel (which can be empty or be a concatenated list of multiple runlevels)
action
process
Possible actions
Possible actions are:
respawn
wait
once
boot
bootwait
powerfail
powerfailnow
powerwait
powerokwait
ctrlaltdel
off
ondemand
initdefault
sysinit
kbrequest
#
# The initdefault action determines the initial
# runlevel of the system.
#
id:3:initdefault:
si::sysinit:/etc/rc.d/init.d/rc S
…
1:2345:respawn:/sbin/agetty --noclear tty1 9600
…
See init.c, function read_inittab for more details.