The init(1M) command replaces the SunOS release 4.x fasthalt command in the SunOS release 5.6 software. Use it to shut down a single-user system. You can use init to place the system in a power-down state (init 0) or into single-user state (init 1).
Note the following changes to the init command:
SunOS release 5.6 system software has eight initialization states (init states or run levels). The default init state is defined in the /etc/inittab file.
The SunOS release 5.6 init command uses a different script for each run level instead of grouping all the run levels together in the /etc/rc, /etc/rc.boot, and /etc/rc.local files. The files, named by run level, are located in the /sbin directory.
System Administration Guide describes this command in detail.
The SunOS release 5.6 init command enables you to control the run level (initialization state) of your system and move easily between various modes of operation. The SunOS release 5.6 /sbin/rc scripts control each individual run level instead of putting all system states into one file. This enables you to make changes in a unique file if you create new scripts or modify existing ones. SunOS release 4.x systems controlled run levels using /etc/rc, /etc/rc.boot, and /etc/rc.local files.
The SunOS release 4.x software had three run levels: prom monitor, single user, and multiuser. These correspond to run levels 0, 1, and 3 in the SunOS release 5.6 software.
Table 8-3 gives an overview of what each run level's /sbin/rc script does.
Table 8-3 SunOS release 5.6 System Initialization Run Levels