System Administration Guide: Basic Administration

System Shutdown Commands

The use of the init and shutdown commands are the primary ways to shut down a system. Both commands perform a clean shutdown of the system. As such, all file system changes are written to the disk, and all system services, processes, and the operating system are terminated normally.

The use of a system's Stop key sequence or turning a system off and then on are not clean shutdowns because system services are terminated abruptly. However, sometimes these actions are needed in emergency situations. For instructions on system recovery techniques, see Chapter 12, Booting a Solaris System (Tasks) andChapter 14, Managing the Solaris Boot Archives (Tasks).

Note –

On x86 systems that are running at least the Solaris 10 6/06 release, pressing and releasing the power button initiates a clean system shutdown. This method is equivalent to using the init 5 command.

The following table describes the various shutdown commands and provides recommendations for using them.

Table 10–1 Shutdown Commands



When To Use 


An executable shell script that calls the init program to shut down the system. The system is brought to run level S by default.

Recommended for servers operating at run level 3 because users are notified of the impending shutdown. Also notified are the systems that are mounting resources from the server that is being shut down.  


An executable that kills all active processes and synchronizes the disks before changing run levels.

Recommended for stand-alone systems when other users will not be affected. Provides a faster system shutdown because users are not notified of the impending shutdown. 


An executable that synchronizes the disks and passes boot instructions to the uadmin system call. In turn, this system call stops the processor.

The init command is the preferred method.

halt, poweroff

An executable that synchronizes the disks and stops the processor.

Not recommended because it doesn't shutdown all processes, and unmount any remaining file systems. Stopping the services, without doing a clean shutdown, should only be done in an emergency or if most of the services are already stopped.