/etc/inittab

inittab entries specify up to four fields separated by colon , the fields are:
identifier:runlevel:action:command
with the following meaning:

inittab Entries
Field	Size and Contents
identifier	14 chars unique object entry id
runlevel	20 chars specifying runlevel ( 0,s,2,3) or runlevel list such as 1234
action	40 chars that specify action on process such as:
	respawn	init process if not started
	wait	start and wait for termination
	bootwait	start and wait only during boot
	initdefault	set initial run level
command	1024 chars shell comand(s) to execute

inittab may contain comments prefixed by # and \ for continuation lines.

Examples:

• is:3:initdefault set network multiuser as default runlevel.
• fs:23:wait:/sbin/bcheckrc < /dev/console > dev/console 2>&1 run file system checks and mount file systems at run level 2
  and 3 getting input from the console and sending output and
  error messages to console.

N.B. the console process must run for all runlevels.