Ubuntu Feisty 7.04 manual page repository

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Provided by: sysvinit_2.86.ds1-14.1ubuntu18_i386

 

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‐
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
               (< 5.2.18) or a.out libraries the limit is 2 characters).
 
               Note:  traditionally,  for  getty and other login processes, the
               value of the id field is kept the same as the suffix of the cor‐
               responding  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 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 pro‐
               cess’s completion.
 
        powerokwait
               This process will be executed as soon as init is  informed  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:
 
               # 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 "3 finger salute".
               ca::ctrlaltdel:/sbin/shutdown -t1 -h now
 
               # Runlevel 2,3: getty on virtual consoles
               # Runlevel   3: getty on terminal (ttyS0) and modem (ttyS1)
               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
               S0:3:respawn:/sbin/getty -L 9600 ttyS0 vt320
               S1:3:respawn:/sbin/mgetty -x0 -D ttyS1
 

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).
telinit(8)
 
INITTAB(5)
 

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