How to find out if Advanced Power Management support available or not under Linux

Advanced Power Management (APM) is an API developed by Intel and Microsoft, which allows BIOS to perform power management.

These days it is outdated and replaced by ACPI (The Advanced Configuration and Power Interface).

Under Linux to find out if, Advanced Power Management support available or not you need to type following commands:

$ apm_available
$ echo $?

It returns three values:

You can also try out following command:

$ apm_available && echo "Yes" || echo "No APM support"

You can use following command to test whether ACPI subsystem is available or not:

$ acpi_available && echo "Yes" || echo "No APM support"