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inittab(4)							   inittab(4)



NAME

  inittab - Controls the initialization	process

SYNOPSIS

  /etc/inittab

DESCRIPTION

  The inittab file provides the	init program with instructions for creating
  and running initialization processes.	 The init program reads	the inittab
  file each time init is invoked.  The file typically contains instructions
  for the default initialization, the creation and control of processes	at
  each run level, and the getty	command, which controls	the activation of
  terminal lines.

  Each line in the inittab file	contains an entry that has four	fields;	each
  field	is separated by	a colon.  There	is no limit to the number of entries
  in the inittab file. The entry syntax	is as follows:

       Identifier:Runlevel:Action:Command

  Indentifier
	    Specifies a	fourteen character field used to uniquely identify an
	    object.

  Runlevel  Specifies a	twenty character field that defines the	run levels in
	    which the object is	to be processed. Runlevel corresponds to a
	    configuration of processes in a system. Each process spawned by
	    the	init command is	assigned one or	more run levels	in which it
	    is allowed to exist.  The run levels are as	follows:

	    0	      Specifies	the halt state.

	    2	      Specifies	multiuser state	without	network	services.

	    3	      Specifies	multiuser state	with network services.

	    S or s    Specifies	single-user state.
  You can define multiple run levels for a process by specifying more than
  one run level	character in any combination.

  Action    Specifies a	twenty character field that tells init how to treat
	    the	specified process.  init recognizes the	following Action
	    values:

	    respawn   Specifies	that if	the process does not exist or if it
		      dies, init starts	it.  If	the process exists, init con-
		      tinues to	process	the inittab file.

	    wait      Specifies	that if	init enters a run level	that matches
		      the run level specified in the inittab file entry, it
		      starts the process and waits for its termination.	 As
		      long as init continues in	this run level,	it does	not
		      act on subsequent	reads of the entry in the inittab
		      file.

	    once      Specifies	that if	init enters a run level	that matches
		      the run level specified in the inittab file, it starts
		      the process and does not wait for	its termination.
		      When the process stops, init does	not restart it.	 If
		      init enters a new	run level where	the process is still
		      running from a previous runlevel change, init does not
		      restart the process.

	    boot      Specifies	that when init first executes and reads	the
		      inittab file, it processes this entry.  The init pro-
		      gram starts the process and does not wait	for its	ter-
		      mination.	  When the process stops, init does not	res-
		      tart it.	The run	level specified	in this	inittab	file
		      entry should be the default run level, or	it must	match
		      the run level in which init operates at boot time.

	    bootwait  Specifies	that when init first executes and reads	the
		      inittab file, it processes this inittab file entry.
		      The init program starts the process, waits for its ter-
		      mination and, when it dies, does not restart the pro-
		      cess.

	    powerfail (This value exists only for SVID3/SVR4 compatibility.)
		      Specifies	that if	init receives the SIGPWR power fail
		      signal, it executes the process associated with this
		      line.

	    powerwait (This value exists only for SVID3/SVR4 compatibility.)
		      Specifies	that if	init receives the SIGPWR power fail
		      signal, it executes the process associated with this
		      line and waits until the process terminates before con-
		      tinuing processing the inittab file.

	    off	      Specifies	that if	the process associated with this line
		      is currently running, init sends the warning signal
		      SIGTERM and waits	20 seconds before sending the kill
		      signal SIGKILL.  If the process does not existent, init
		      ignores the inittab entry.

	    initdefault
		      Specifies	that a line with this action is	processed
		      when init	is originally invoked.	The init program uses
		      this line	to determine the run level to enter origi-
		      nally.  It determines this by taking the highest run
		      level specified in the run level field and using that
		      as its initial state. If the run level field is empty,
		      this is interpreted as 0s23, causing init	to enter run
		      level 3.	If init	does not find an initdefault entry in
		      the inittab file,	it requests an initial run level from
		      the operator.

	    sysinit   Specifies	that entries of	this type are executed before
		      init tries to access the console.	 This inittab file
		      entry should be used only	to initialize devices on
		      which init could attempt to request a run	level.

  Command   Specifies a	1024 character field that contains the sh command to
	    be executed.  The command is prefixed with exec.  Any legitimate
	    sh syntax can appear in the	command	field. Comments	can be
	    inserted be	specifying a number sign (#). The line continuation
	    character \	can be placed at the end of a line.

EXAMPLES

  The following	is an example of an inittab file entry for a terminal line:


       tty01:23:respawn:/usr/sbin/getty	/dev/tty08 9600	vt100

FILES

  /usr/sbin/getty
	    Specifies the command that initializes and controls	terminal
	    lines.

RELATED	INFORMATION

  Commands: init(8), getty(8)

  Functions:  kill(2)