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

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

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


       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.

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

       action describes which action should be taken.

	      specifies the process to be executed.  If the process field starts with a `+' char-
	      acter, 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 runlevels.  For example,
       123  specifies that the process should be started in runlevels 1, 2, and 3.  The runlevels
       for ondemand entries may contain 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:

	      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.

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

       off    This does nothing.

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

	      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.

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

	      The  process  will  be  executed when the power goes down. Init is usually informed
	      about this by a process talking to a UPS connected to the computer.  Init will wait
	      for the process to finish before continuing.

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

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

	      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).

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

	      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 writ-
	      ing). Basically you want to map some keyboard combination to  the  "KeyboardSignal"
	      action.  For example, to map Alt-Uparrow for this purpose use the following in your
	      keymaps file:

	      alt keycode 103 = KeyboardSignal

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

	      # inittab for linux
	      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

	      # System initialization before anything else.

	      # Runlevel 0,6 is halt and reboot, 1 is maintenance mode.

	      # 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


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

       init(8), telinit(8)

					   May 19, 1998 			       INITTAB(5)
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