System Shutdown Commands
The shutdown and init commands are the primary commands that are used to shut down a system. Both commands perform a clean shutdown of the system. As such, all file system changes are written to disk, and all system services, processes, and the operating system are terminated normally. System services managed by SMF are shutdown in reverse dependency order.
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.
The following table describes the various shutdown commands and provides recommendations for using them.
Table 4 Shutdown Commands
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shutdown
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An executable that calls the init program to shut down the system. The system is brought to run level S by default. |
Use this command to shut down systems that are operating at run level 3.
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init
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An executable that terminates all active processes and synchronizes the disks before changing run levels. |
Because this command provides a faster system shutdown, the command is preferred for shutting down stand-alone systems when other users will not be affected. There is no notification sent for an impending shutdown.
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reboot
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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.
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halt, poweroff
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An executable that synchronizes the disks and stops the processor.
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Not recommended because it does not shut down all processes or 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.
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