ACPI hotkeys

Summary

There are many guides on how to configure multimedia hotkeys using program such as xev or keyTouch. However, this guide explains how to use the simple utility of acpi_listen and generate your own script for hotkeys.

Who Should be Using This Guide

This guide assumes that you know your keyboard signals through acpi. If you do not know whether or not this is the case, I suggest looking:

• Using Multimedia Keys in Linux
• Extra Keyboard Keys - keyTouch

Installing Necessary Tools

You should already have these tools installed, but just to make sure you will need

# pacman -S acpid

Refer to this guide on what modules you should load (i.e. through /etc/rc.conf or modprobe)

Using acpi_listen

Under root, or with sufficient access to the input devices, run:

# acpi_listen

If pressing a special key, such as previous or next, receives a response that looks similar to:

hkey VALZ 00000000 00000b31

then all is well and we can continue.

If nothing appears on the screen during execution of the acpi_listen, that means that the pressed keys do not generate an ACPI event. In this case you can't use ACPI for monitoring these keys. See the page Hotkeys for other ways of mapping keys.

Configuring ACPID

The ACPI daemon reacts to ACPI events according to the handler.sh file. This is located in /etc/acpi/handler.sh

You can either directly edit this file, to react to the ACPI events, or you can point it to another shell script (i.e. /etc/acpi/hotkeys.sh)

Under the section

case "$1" in

Add the following lines:

hkey)
	case "$4" in
		00000b31)
		echo "PreviousButton pressed!"
		exailectl p
		;;
	00000b32)
		echo "NextButton pressed!"
		exailectl n
		;;
	00000b33)
		echo "Play/PauseButton pressed!"
		exailectl pp
		echo "executed.."
		;;
	00000b30)
		echo "StopButton pressed!"
		exailectl s
		;;
	*)
		echo "Hotkey Else: $4"
		;;
	esac
	;;

The '00000b31' etc. values are the response received from acpi_listen. In 'hkey VALZ 00000000 00000b31', $4 is the final part, which was what distinguished my keys apart.

Also, the exailectl script is a brief shell script I created for controlling Exaile music player. As the ACPID is run from root, you will need to use

sudo -u (username) exaile

for example, otherwise it will not detect your user-level program and recreate another.

Old: Sample Script

As keyTouch and other keyboard programs did not work for me, or did not work effectively, prior to editing my handler.sh file I created my own script that runs in the background and reacts directly from the output of acpi_listen. However it is a poor method to use, caused my laptop to be constantly active and noisy. I have provided the script here anyway, feel free to use it / modify it to suit your needs and post suggestions on how it can be improved. Currently, it is setup for a Toshiba Satellite A50 laptop to control exaile, but can be modified very easily for Amarok, Xine or other non-music related functions (internet, email).

export STOP_MYHOTKEY=0
i=`acpi_listen -c 1`
case "$i" in
	"hkey VALZ 00000000 00000b31")
		#echo "PREVIOUS"
		exaile -p
		;;
	"hkey VALZ 00000000 00000b32")
		#echo "NEXT"
		exaile -n
		;;
	"hkey VALZ 00000000 00000b33")
		exaile -t
		;;
	"hkey VALZ 00000000 00000b30")
		#echo "STOP"
		exaile -s
		;;
	*)
		#echo "ELSE: $i"
		;;
esac
e=`echo $STOP_MYHOTKEY`
if [ "$e" != "1" ]
then
	./myHotkey.sh &
fi

Note: This does not need to be run as root if you can receive an acpi_listen response from a user account (again, meaning you have access to the input devices).