+-------------------------------------------------------------------+
|                                                                   |
|        WIKI - [acpid] Handle all events in a single script        |
|                                                                   |
+-------------------------------------------------------------------+

PREREQUISITES

* Make sure that all ACPI-related kernel options are enabled. 
  More info: https://wiki.gentoo.org/wiki/ACPI#Kernel


IDENTIFYING ACPI EVENTS

* Enable acpid.

  $ ln -s /etc/sv/acpid/ /var/service/


* Run acpi_listen. This waits for ACPI events and outputs them.

  # For this example, pressing the volume mute button will print 
    something like:

  $ button/mute MUTE 00000080 00000000 K


NOTE: Some 'Fn + *' keys might not appear as they are hardware-bound 
      (e.g. WLAN toggle). Just test them all and see what works. For 
      most laptops, this will also detect lid events 
      (e.g. opening or closing).


READ ALL EVENTS

* Create a file under /etc/acpi/events/ (just create these 
  directories if they are missing) containing the following:

  # /etc/acpi/events/anything
  event=.*
  action=/etc/acpi/handler.sh %e


* This will match any detected event and run the action 
  file (see below).


THE HANDLER SCRIPT

* During an event, acpid will run a corresponding action which can 
  now be handled by a single script. This is possible as the events 
  are passed literally as multiple parameters into the script. As 
  for our example:

  button/mute MUTE 00000080 00000000 K
  $1=button/mute
  $2=MUTE
  $3=00000080
  $4=00000000
  $5=K

* Here's a very simple script:

  # /etc/acpi/handler.sh

  #!/bin/sh

  case $1 in
      button/mute)
          amixer sset Master toggle
      ;;
  esac

  # Don't forget to make this file executable
  $ chmod +x /etc/acpi/handler.sh


* Restart `acpid`.

  $ sv restart acpid