Keep the following in mind when you shut down a system:
Use the init and shutdown commands to shut down a system. Both commands perform a clean system shutdown, which means that all system processes and services are terminated normally.
For x86 based systems that are running at least the Solaris 10 6/06 release, you can initiate a clean system shutdown by pressing and releasing the power button. Shutting down an x86 based system in this manner is equivalent to using the init 5 command to shut down a system. On some x86 based systems, the BIOS configuration might prevent the power button from initiating a system shutdown. To use the power button, reconfigure the BIOS.
Use the shutdown command to shut down a server. Logged-in users and systems that mount resources from the server are notified before the server is shut down. Additional notification of system shutdowns by electronic mail is also recommended so that users can prepare for system downtime.
You need superuser privileges to use the shutdown or init command to shut down a system.
Both shutdown and init commands take a run level as an argument.
The three most common run levels are as follows:
Run level 3 – All system resources are available and users can log in. By default, booting a system brings it to run level 3, which is used for normal day-to-day operations. This run level is also known as multiuser level with NFS resources shared.
Run level 6 – Stops the operating system and reboots to the state that is defined by the initdefault entry in the /etc/inittab file.
Run level 0 – The operating system is shut down, and it is safe to turn off power. You need to bring a system to run level 0 whenever you move a system, or add or remove hardware.
Run levels are fully described in Chapter 16, Managing Services (Overview).