Index for Section 4

Alphabetical listing for I

Bottom of page

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
		      continues 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
		      program starts the process and does not wait for its
		      termination.   When the process stops, init does not
		      restart 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
		      termination and, when it dies, does not restart the
		      process.

	    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
		      continuing 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
		      originally.  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)

Index for Section 4

Alphabetical listing for I

Top of page