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INITTAB(5)	      Linux System Administrator's Manual	    INITTAB(5)

NAME
       inittab	-  format of the inittab file used by the sysv-compatible init
       process

DESCRIPTION
       The inittab file	describes which	processes are started  at  bootup  and
       during  normal  operation  (e.g.	/etc/init.d/boot, /etc/init.d/rc, get-
       tys...).	 Init(8) distinguishes multiple	runlevels, each	of  which  can
       have  its  own  set of processes	that are started.  Valid runlevels are
       0-6 plus	A, B, and C for	ondemand entries.  An  entry  in  the  inittab
       file has	the following format:

	      id:runlevels:action:process

       Lines beginning with `#'	are ignored.

       id     is a unique sequence of 1-4 characters which identifies an entry
	      in inittab (for versions of sysvinit compiled with  libraries  <
	      5.2.18 or	a.out libraries	the limit is 2 characters).

	      Note:  For  gettys or other login	processes, the id field	should
	      be the tty suffix	of the corresponding tty,  e.g.	 1  for	 tty1.
	      Otherwise, the login accounting might not	work correctly.

       runlevels
	      lists  the  runlevels  for  which	the specified action should be
	      taken.

       action describes	which action should be taken.

       process
	      specifies	the process to be  executed.   If  the	process	 field
	      starts  with  a  `+'  character,	init will not do utmp and wtmp
	      accounting for that process.  This is  needed  for  gettys  that
	      insist  on doing their own utmp/wtmp housekeeping.  This is also
	      a	historic bug.

       The runlevels field may contain multiple	characters for different  run-
       levels.	 For example, 123 specifies that the process should be started
       in runlevels 1, 2, and 3.  The runlevels	for ondemand entries may  con-
       tain an A, B, or	C.  The	runlevels field	of sysinit, boot, and bootwait
       entries are ignored.

       When the	system runlevel	is changed, any	running	processes that are not
       specified  for  the  new	 runlevel are killed, first with SIGTERM, then
       with SIGKILL.

       Valid actions for the action field are:

       respawn
	      The process will	be  restarted  whenever	 it  terminates	 (e.g.
	      getty).

       wait   The  process will	be started once	when the specified runlevel is
	      entered and init will wait for its termination.

       once   The process will be executed once	when the specified runlevel is
	      entered.

       boot   The  process will	be executed during system boot.	 The runlevels
	      field is ignored.

       bootwait
	      The process will be executed  during  system  boot,  while  init
	      waits  for  its termination (e.g.	/etc/rc).  The runlevels field
	      is ignored.

       off    This does	nothing.

       ondemand
	      A	process	marked with an	ondemand  runlevel  will  be  executed
	      whenever the specified ondemand runlevel is called.  However, no
	      runlevel change will occur (ondemand runlevels are `a', `b', and
	      `c').

       initdefault
	      An  initdefault  entry  specifies	 the  runlevel which should be
	      entered after system boot.  If none exists, init will ask	for  a
	      runlevel on the console. The process field is ignored.

       sysinit
	      The process will be executed during system boot. It will be exe-
	      cuted before any boot or	bootwait entries.  The runlevels field
	      is ignored.

       powerwait
	      The  process  will be executed when the power goes down. Init is
	      usually informed about this by a process talking to a  UPS  con-
	      nected  to the computer.	Init will wait for the process to fin-
	      ish before continuing.

       powerfail
	      As for powerwait,	 except	 that  init  does  not	wait  for  the
	      process's	completion.

       powerokwait
	      This  process  will  be  executed	as soon	as init	is informormed
	      that the power has been restored.

       powerfailnow
	      This process will	be executed when init is told that the battery
	      of  the  external	 UPS  is almost	empty and the power is failing
	      (provided	that the external UPS and the monitoring  process  are
	      able to detect this condition).

       ctrlaltdel
	      The  process will	be executed when init receives the SIGINT sig-
	      nal.  This means that someone on the system console has  pressed
	      the CTRL-ALT-DEL key combination.	Typically one wants to execute
	      some sort	of shutdown either to get into single-user level or to
	      reboot the machine.

       kbrequest
	      The  process  will  be executed when init	receives a signal from
	      the keyboard handler that	a special key combination was  pressed
	      on the console keyboard.

	      The  documentation  for  this function is	not complete yet; more
	      documentation can	be found in the	kbd-x.xx packages (most	recent
	      was kbd-0.94 at the time of this writing). Basically you want to
	      map some keyboard	combination to	the  "KeyboardSignal"  action.
	      For example, to map Alt-Uparrow for this purpose use the follow-
	      ing in your keymaps file:

	      alt keycode 103 =	KeyboardSignal

EXAMPLES
       This is an example of a inittab which resembles the old Linux inittab:

	      #	inittab	for linux
	      id:1:initdefault:
	      rc::bootwait:/etc/rc
	      1:1:respawn:/etc/getty 9600 tty1
	      2:1:respawn:/etc/getty 9600 tty2
	      3:1:respawn:/etc/getty 9600 tty3
	      4:1:respawn:/etc/getty 9600 tty4

       This inittab file executes /etc/rc during boot  and  starts  gettys  on
       tty1-tty4.

       A  more	elaborate  inittab  with different runlevels (see the comments
       inside):

	      #	Level to run in
	      id:2:initdefault:

	      #	System initialization before anything else.
	      si::sysinit:/etc/rc.d/bcheckrc

	      #	Runlevel 0,6 is	halt and reboot, 1 is maintenance mode.
	      l0:0:wait:/etc/rc.d/rc.halt
	      l1:1:wait:/etc/rc.d/rc.single
	      l2:2345:wait:/etc/rc.d/rc.multi
	      l6:6:wait:/etc/rc.d/rc.reboot

	      #	What to	do at the "3 finger salute".
	      ca::ctrlaltdel:/sbin/shutdown -t5	-rf now

	      #	Runlevel 2&3: getty on console,	level 3	also getty on modem port.
	      1:23:respawn:/sbin/getty tty1 VC linux
	      2:23:respawn:/sbin/getty tty2 VC linux
	      3:23:respawn:/sbin/getty tty3 VC linux
	      4:23:respawn:/sbin/getty tty4 VC linux
	      S2:3:respawn:/sbin/uugetty ttyS2 M19200

FILES
       /etc/inittab

AUTHOR
       Init was	written	by Miquel van Smoorenburg (miquels@cistron.nl).	  This
       manual  page  was written by Sebastian Lederer (lederer@francium.infor-
       matik.uni-bonn.de) and modified by Michael Haardt  (u31b3hs@pool.infor-
       matik.rwth-aachen.de).

SEE ALSO
       init(8),	telinit(8)

				 May 19, 1998			    INITTAB(5)

NAME | DESCRIPTION | EXAMPLES | FILES | AUTHOR | SEE ALSO

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