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 inittab(4)							  inittab(4)




 NAME
      inittab - script for the boot init process

 DESCRIPTION
      The /etc/inittab file supplies the script to the boot init daemon in
      its role as a general process dispatcher (see init(1M)).	The process
      that constitutes the majority of boot init's process dispatching
      activities is the line process /usr/sbin/getty that initiates
      individual terminal lines.  Other processes typically dispatched by
      boot init are daemons and shells.

      The inittab file is composed of entries that are position-dependent
      and have the following format:

	   id:rstate:action:process

      Each entry is delimited by a newline; however, a backslash (\)
      preceding a newline indicates a continuation of the entry.  Up to 1024
      characters per entry are permitted.  Comments can be inserted in the
      process field by starting a "word" with a # (see sh(1)).	Comments for
      lines that spawn gettys are displayed by the who command (see who(1)).
      It is expected that they will contain some information about the line
      such as the location.  There are no limits (other than maximum entry
      size) imposed on the number of entries within the inittab file.

      The entry fields are:

	   id	     A one- to four-character value used to uniquely
		     identify an entry.	 Duplicate entries cause an error
		     message to be issued, but are otherwise ignored.  The
		     use of a four-character value to identify an entry is
		     strongly recommended (see WARNINGS below).

	   rstate    Defines the run level in which this entry is to be
		     processed.	 Run levels correspond to a configuration of
		     processes in the system where each process spawned by
		     boot init is assigned one or more run levels in which
		     it is allowed to exist.  Run levels are represented by
		     a number in the range 0 through 6.	 For example, if the
		     system is in run level 1, only those entries having a 1
		     in their rstate field are processed.

		     When boot init is requested to change run levels, all
		     processes that do not have an entry in the rstate field
		     for the target run level are sent the warning signal
		     (SIGTERM) and allowed a 20-second grace period before
		     being forcibly terminated by a kill signal (SIGKILL).
		     You can specify multiple run levels for a process by
		     entering more than one run level value in any
		     combination.  If no run level is specified, the process
		     is assumed to be valid for all run levels, 0 through 6.



 Hewlett-Packard Company	    - 1 -   HP-UX Release 11i: November 2000






 inittab(4)							  inittab(4)




		     Three other values, a, b and c, can also appear in the
		     rstate field, even though they are not true run levels.
		     Entries having these characters in the rstate field are
		     processed only when a user init process requests them
		     to be run (regardless of the current system run level).
		     They differ from run levels in that boot init can never
		     enter "run level" a, b, or c.  Also, a request for the
		     execution of any of these processes does not change the
		     current numeric run level.

		     Furthermore, a process started by an a, b, or c option
		     is not killed when boot init changes levels.  A process
		     is killed only if its line in inittab is marked off in
		     the action field, its line is deleted entirely from
		     inittab, or boot init goes into the single-user state.

	   action    A keyword in this field tells boot init how to treat
		     the process specified in the process field.  The
		     following actions can be specified:

		     boot	       Process the entry only at boot init's
				       boot-time read of the inittab file.
				       Boot init starts the process, does
				       not wait for its termination, and
				       when it dies, does not restart the
				       process.	 In order for this
				       instruction to be meaningful, the
				       rstate should be the default or it
				       must match boot init's run level at
				       boot time.  This action is useful for
				       an initialization function following
				       a hardware boot of the system.

		     bootwait	       Process the entry only at boot init's
				       boot-time read of the inittab file.
				       Boot init starts the process, waits
				       for its termination, and, when it
				       dies, does not restart the process.

		     initdefault       An entry with this action is only
				       scanned when boot init is initially
				       invoked.	 Boot init uses this entry,
				       if it exists, to determine which run
				       level to enter initially.  It does
				       this by taking the highest run level
				       specified in the rstate field and
				       using that as its initial state.	 If
				       the rstate field is empty, boot init
				       enters run level 6.





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 inittab(4)							  inittab(4)




				       The initdefault entry cannot specify
				       that boot init start in the single-
				       user state.  Additionally, if boot
				       init does not find an initdefault
				       entry in inittab, it requests an
				       initial run level from the user at
				       boot time.

		     off	       If the process associated with this
				       entry is currently running, send the
				       warning signal (SIGTERM) and wait 20
				       seconds before forcibly terminating
				       the process via the kill signal
				       (SIGKILL).  If the process is
				       nonexistent, ignore the entry.

		     once	       When boot init enters a run level
				       that matches the entry's rstate,
				       start the process and do not wait for
				       its termination.	 When it dies, do
				       not restart the process.	 If boot
				       init enters a new run level but the
				       process is still running from a
				       previous run level change, the
				       process is not restarted.

		     ondemand	       This instruction is really a synonym
				       for the respawn action.	It is
				       functionally identical to respawn but
				       is given a different keyword in order
				       to divorce its association with run
				       levels.	This is used only with the
				       a, b, or c values described in the
				       rstate field.

		     powerfail	       Execute the process associated with
				       this entry only when boot init
				       receives a power-fail signal (SIGPWR
				       see signal(5)).

		     powerwait	       Execute the process associated with
				       this entry only when boot init
				       receives a power-fail signal (SIGPWR)
				       and wait until it terminates before
				       continuing any processing of inittab.

		     respawn	       If the process does not exist, start
				       the process; do not wait for its
				       termination (continue scanning the
				       inittab file).  When it dies, restart
				       the process.  If the process



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 inittab(4)							  inittab(4)




				       currently exists, do nothing and
				       continue scanning the inittab file.

		     sysinit	       Entries of this type are executed
				       before boot init tries to access the
				       console.	 It is expected that this
				       entry will be only used to initialize
				       devices on which boot init might
				       attempt to obtain run level
				       information.  These entries are
				       executed and waited for before
				       continuing.

		     wait	       When boot init enters the run level
				       that matches the entry's rstate,
				       start the process and wait for its
				       termination.  Any subsequent reads of
				       the inittab file while boot init is
				       in the same run level cause boot init
				       to ignore this entry.

	   process   This is a sh command to be executed.  The entire
		     process field is prefixed with exec and passed to a
		     forked sh as "sh -c 'exec command'".  For this reason,
		     any sh syntax that can legally follow exec can appear
		     in the process field.  Comments can be inserted by
		     using the ; #comment syntax.

 WARNINGS
      The use of a four-character id is strongly recommended.  Many pty
      servers use the last two characters of the pty name as an id.  If an
      id chosen by a pty server collides with one used in the inittab file,
      the /etc/utmp file can become corrupted.	A corrupt /etc/utmp file can
      cause commands such as who to report inaccurate information.

 FILES
      /etc/inittab	  File of processes dispatched by boot init.

 SEE ALSO
      sh(1), getty(1M), exec(2), open(2), signal(5).














 Hewlett-Packard Company	    - 4 -   HP-UX Release 11i: November 2000