rc0(1M)                                                             rc0(1M)


   NAME
         rc0 - run commands performed to stop the operating system

   SYNOPSIS
         /sbin/rc0

   DESCRIPTION
         This file is executed at each system state change that needs to have
         the system in an inactive state.  It is responsible for those actions
         that bring the system to a quiescent state, traditionally called
         ``shutdown''.

         There are three system states that require this procedure.  They are
         state 0 (the system halt state), state 5 (the firmware state), and
         state 6 (the reboot state).  Whenever a change to one of these states
         occurs, the rc0 procedure is run.  The entry in /sbin/inittab might
         read:

               s0:056:wait:/sbin/rc0 >/dev/console 2>&1 </dev/console

         Some of the actions performed by rc0 are carried out by files in the
         directory /usr/sbin/shutdown.d.  and files beginning with K in
         /sbin/rc0.d.  These files are executed in ASCII order (see FILES
         below for more information), terminating some system service.  The
         combination of commands in rc0 and files in /usr/sbin/shutdown.d and
         /sbin/rc0.d determines how the system is shut down.

         The recommended sequence for rc0 is:

         Stop System Services and Daemons.

               Various system services (such as LP Spooler) are gracefully
               terminated.

               When new services are added that should be terminated when the
               system is shut down, the appropriate files are installed in
               /usr/sbin/shutdown.d and /sbin/rc0.d.

         Terminate Processes

               SIGTERM signals are sent to all running processes by
               killall(1M).  Processes stop themselves cleanly if sent
               SIGTERM.

         Kill Processes

               SIGKILL signals are sent to all remaining processes; no process
               can resist SIGKILL.

               At this point the only processes left are those associated with
               rc0 and processes 0 and 1, which are special to the operating


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   rc0(1M)                                                             rc0(1M)


               system.

         Unmount All File Systems

               Only the root file system (/) remains mounted.

         Depending on which system state the systems end up in (0, 5, or 6),
         the entries in /sbin/inittab will direct what happens next.  If the
         /sbin/inittab has not defined any other actions to be performed as in
         the case of system state 0, then the operating system will have
         nothing to do.  It should not be possible to get the system's
         attention.  The only thing that can be done is to turn off the power
         or possibly get the attention of a firmware monitor.  The command can
         be used only by the super-user.

   FILES
         The execution by /usr/bin/sh of any files in /usr/sbin/shutdown.d
         occurs in ASCII sort-sequence order.  See rc2(1M) for more
         information.

   SEE ALSO
         killall(1M), rc2(1M), shutdown(1M).































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