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!!!INITTAB

----
!!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, gettys...). 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 the ''old'' libc5 (
''


Note: traditionally, for getty and other login processes,
the value of the ''id'' field is kept the same as the
suffix of the corresponding tty, e.g. __1__ for
__tty1__. Some ancient login accounting programs might
expect this, though I can't think of any.


''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 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:


__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
executed 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
connected to the computer. __Init__ will wait for the
process to finish 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 signal. 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


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:
# Boot-time system configuration/initialization script.
si::sysinit:/etc/init.d/rcS
# What to do in single-user mode.
~:S:wait:/sbin/sulogin
# /etc/init.d executes the S and K scripts upon change
# of runlevel.
#
# Runlevel 0 is halt.
# Runlevel 1 is single-user.
# Runlevels 2-5 are multi-user.
# Runlevel 6 is reboot.
l0:0:wait:/etc/init.d/rc 0
l1:1:wait:/etc/init.d/rc 1
l2:2:wait:/etc/init.d/rc 2
l3:3:wait:/etc/init.d/rc 3
l4:4:wait:/etc/init.d/rc 4
l5:5:wait:/etc/init.d/rc 5
l6:6:wait:/etc/init.d/rc 6
# What to do at the
!!FILES


/etc/inittab
!!AUTHOR


__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).
!!SEE ALSO


init(8), telinit(8)
----
13 pages link to inittab(5):
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Last edited on Friday, October 3, 2003 4:54:31 pm by JohnMcPherson
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