Modern computers support the Advanced Configuration and Power Interface (ACPI) to allow intelligent power management on your system and to query battery and configuration status.

ACPID is a completely flexible, totally extensible daemon for delivering ACPI events. It listens on netlink interface (or on the deprecated file /proc/acpi/event), and when an event occurs, executes programs to handle the event. The programs it executes are configured through a set of configuration files, which can be dropped into place by packages or by the admin.