NAME

rc0 − run commands performed to stop the operating system

SYNOPSIS

/etc/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 /etc/rc0 procedure is run.  The entry in /etc/inittab might read:

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

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

The recommended sequence for /etc/rc0 is:

Stop System Services and Daemons. 

Various system services (such as 3BNET Local Area Network or 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 /etc/shutdown.d and /etc/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 /etc/rc0 and processes 0 and 1, which are special to the operating 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 /etc/inittab will direct what happens next.  If the /etc/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 /bin/sh of any files in /etc/shutdown.d occurs in ascii sort-sequence order.  See rc2(1M) for more information. 

SEE ALSO

killall(1M), rc2(1M), shutdown(1M). 

September 02, 1992