Special configuration in /etc/inittab

The /etc/inittab  has some special features that allow init  to react to special circumstances. These special features are marked by special keywords in the third field. Some examples:

powerwait

Allows init  to shut the system down, when the power fails. This assumes the use of a UPS, and software that watches the UPS and informs init  that the power is off.

ctrlaltdel

Allows init  to reboot the system, when the user presses control-alt-del on the console keyboard. Note that the system administrator can configure the reaction to C-A-D to be something else instead, e.g., to be ignored, if the system is in a public location.

sysinit

Command to be run when the system is booted. This command usually cleans up /tmp , for example.

The list above is not exhaustive. See your inittab (5) manual page for all possibilities, and for details on how to use the above ones.