General Information


As with Windows, BeOS, Linux and many other OSes around, you should never turn off the system simply by switching off the power supply, although most newer SGIs will shutdown correctly when the power button is pressed.

But normally, the system administrator, or any other user with root privileges should issue an shutdown command. This command is also responsible for changing runlevels.

What are Runlevels?

In UNIX the term runlevel refers to a well defined configuration of services, daemons, programs etc for booting the operating system. This is useful for administrating the system, as there is a configuration withpout networking etc. The following table lists the available configurations in IRIX 6.5:

Runlevel Configuration
0 Shutdown the machine for power off or go to firmware monitor.
s or S Single user mode, a minimal system environment for system maintenance purposes. If booting, only the / (root) filesystem is mounted.
1 System administration mode. In IRIX, init actually uses the /etc/shutdown script to change the run level to single user mode.
2 Normal multi-user mode. This is the default standard run level for IRIX.
6 Reboot run level, this reboots the system.

Changing the Runlevel

With root-priviliges, you can simply change the active runlevel or shutdown the machine with the command shutdown. As you can see in the table above, this command is not only used for shutting down the machine, but you can also switch from a single user mode into the normal operating mode.

The syntax of shutdown is as follows:

shutdown [ -y ] [ -ggrace_period [ -iinit_state ] [ -p ]

The parameters have the following meaning:

Option Meaning
-y Pre-answers the confirmation question so the command can be run without user intervention. Else the system will wait a default of 60 seconds and ask for confirmation.
-ggrace_period Allows the user to change the number of seconds from the 60-second default.
-iinit_state Specifies the state that the system will boot into. By default, system state "0" is used for stopping the machine.
-p If the new init_state is 0, -p requests that the power be turned off after the system is shut down. Only newer systems support this.


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