inittab (5)


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


       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-
       tys...).  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:


       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

       action describes which action should be taken.

              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:

              The process will  be  restarted  whenever  it  terminates  (e.g.

       wait   The  process will be started once when the specified runlevel is
              entered and init will wait for its termination.
              waits  for  its termination (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 runlevels are `a', `b', and

              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 exe-
              cuted 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  con-
              nected  to the computer.  Init will wait for the process to fin-
              ish before continuing.

              As for powerwait, except that init does not wait  for  the  pro-
              cess'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 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.

              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.
              # 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

       A  more  elaborate  inittab  with different runlevels (see the comments

              # 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 (   This
       manual  page  was written by Sebastian Lederer (lederer@francium.infor- and modified by Michael Haardt  (u31b3hs@pool.infor-


       init(8), telinit(8)

                                 May 19, 1998                       inittab(5)