Script to control keyboard backlight brightness on a Chromebook Pixel running Ubuntu. Includes extra bits like restore old session value on boot, dim keyboard on screen lock, restoring value when resuming from suspend, and so on. Relies on kernel module acpi_call (instructions below).

install-kbd-backlight.sh

#!/bin/sh
# This script will install the files below.
# Please look through them first so you know what will happen.

# Install by running this command:
# curl -fL https://gist.githubusercontent.com/stefansundin/7003429/raw/install-kbd-backlight.sh | sh

# Uninstall with:
# sudo rm /opt/kbd-{backlight,lock}.sh /etc/pm/sleep.d/70-kbd-backlight
# rm ~/.config/autostart/kbd-{backlight,lock}.sh.desktop

echo
echo "Installing /opt/kbd-backlight.sh"
echo "           /opt/kbd-lock.sh"
echo "           /etc/pm/sleep.d/70-kbd-backlight"
echo "           $HOME/.config/autostart/kbd-backlight.sh.desktop"
echo "       and $HOME/.config/autostart/kbd-lock.sh.desktop"
echo
echo Please provide your sudo password if prompted.
echo

sudo curl -fL -o /opt/kbd-backlight.sh https://gist.githubusercontent.com/stefansundin/7003429/raw/kbd-backlight.sh
echo
sudo curl -fL -o /opt/kbd-lock.sh https://gist.githubusercontent.com/stefansundin/7003429/raw/kbd-lock.sh
echo
sudo curl -fL -o /etc/pm/sleep.d/70-kbd-backlight https://gist.githubusercontent.com/stefansundin/7003429/raw/z-70-kbd-backlight
echo
sudo chmod 755 /opt/kbd-backlight.sh /opt/kbd-lock.sh /etc/pm/sleep.d/70-kbd-backlight

sudo sed -i "s/USER=username/USER=$USER/g" /etc/pm/sleep.d/70-kbd-backlight

cat > $HOME/.config/autostart/kbd-backlight.sh.desktop << EOF
[Desktop Entry]
Type=Application
Exec=/opt/kbd-backlight.sh boot
Hidden=false
NoDisplay=false
X-GNOME-Autostart-enabled=true
Name=Keyboard backlight (restore on login)
Comment=https://gist.github.com/stefansundin/7003429/
EOF

cat > $HOME/.config/autostart/kbd-lock.sh.desktop << EOF
[Desktop Entry]
Type=Application
Exec=/opt/kbd-lock.sh
Hidden=false
NoDisplay=false
X-GNOME-Autostart-enabled=true
Name=Keyboard backlight (dim on lock)
Comment=https://gist.github.com/stefansundin/7003429/
EOF

cat << EOF
Done.

Instructions for installing acpi_call:

sudo apt-get install git build-essential
git clone https://github.com/mkottman/acpi_call.git
cd acpi_call
make
sudo make install
sudo depmod
sudo modprobe acpi_call
sudo vim /etc/modules
acpi_call

You may then remove the acpi_call directory.
Note that you may have to recompile acpi_call when you update your kernel,
but probably not for minor updates.

Make acpi_call usable without sudo:

sudo chmod 666 /proc/acpi/call
sudo vim /etc/rc.local
chmod 666 /proc/acpi/call


You may then try changing the keyboard backlight value with:

You can now adjust the brightness with this command:
echo "\_SB.KBLT.KBCM 0" > /proc/acpi/call
or: /opt/kbd-backlight.sh 0
Use 100 to turn it fully on again. Use a value in between to adjust the brightness.

I recommend that you set your keyboard shortcuts in CCSM instead of the normal
keyboard shortcut manager, because many shortcuts set there will just stop
working after reboot. Be *very* careful with this tool!!!

sudo apt-get install compizconfig-settings-manager
ccsm

Enable the 'Commands' plugin and set these commands:
/opt/kbd-backlight.sh up
/opt/kbd-backlight.sh down
/opt/kbd-backlight.sh 100
/opt/kbd-backlight.sh 0

And then the key bindings:
<Alt>F7
<Alt>F6
<Shift><Alt>F7
<Shift><Alt>F6


Uninstall with:
sudo rm /opt/kbd-{backlight,lock}.sh /etc/pm/sleep.d/70-kbd-backlight
rm ~/.config/autostart/kbd-{backlight,lock}.sh.desktop
You may also want to remove your keyboard shortcuts in CCSM.

I recommend Chromebook users to also look at my other gist for mapping the
function keys with Xmodmap: https://gist.github.com/stefansundin/6987698

Donations are welcome at http://stefansundin.com/donate (PayPal)

(scroll up and read all output)

EOF

kbd-backlight.sh

#!/bin/bash
# Script to control keyboard backlight brightness on a Chromebook Pixel running Ubuntu.
# The current brightness value is stored in ~/.kbd-backlight-value.
# sudo curl -fL -o /opt/kbd-backlight.sh https://gist.githubusercontent.com/stefansundin/7003429/raw/kbd-backlight.sh

if [ ! -f ~/.kbd-backlight-value ]; then
	echo "First run: creating $HOME/.kbd-backlight-value"
	echo 100 > ~/.kbd-backlight-value
fi

read val < ~/.kbd-backlight-value
echo Current value: $val

if [[ -z $val || $val == *[!0-9]* ]]; then
	echo "Value is not a number, assuming 100"
	val=100
fi

if [ -z "$1" ]; then
	echo No argument, restoring stored value
elif [ "$1" == "fade" ]; then
	for i in $(seq 0 $val); do
		echo "\_SB.KBLT.KBCM $i" > /proc/acpi/call
		sleep 0.1
	done
elif [ "$1" == "up" ]; then
	val=$(($val+10))
elif [ "$1" == "down" ]; then
	val=$(($val-10))
elif [ "$1" == "dim" ]; then
	for i in $(seq $val -1 20); do
		echo "\_SB.KBLT.KBCM $i" > /proc/acpi/call
		sleep 0.05
	done
	exit 0
elif [ "$1" == "boot" ]; then
	for i in $(seq 100 -1 $val); do
		echo "\_SB.KBLT.KBCM $i" > /proc/acpi/call
		sleep 0.05
	done
	exit 0
else
	val=$1
fi

if [ "$val" -gt "100" ]; then
	val=100
elif [ "$val" -lt "0" ]; then
	val=0
fi

echo New value: $val
echo "\_SB.KBLT.KBCM $val" > /proc/acpi/call
echo $val > ~/.kbd-backlight-value

kbd-lock.sh

#!/bin/bash
# Script to monitor when the computer is locked and dim the keyboard backlight.
# sudo curl -fL -o /opt/kbd-lock.sh https://gist.githubusercontent.com/stefansundin/7003429/raw/kbd-lock.sh

dbus-monitor --session "type='signal',interface='org.gnome.ScreenSaver',member='ActiveChanged'" | (
while true; do
	read x
	if [ "$x" == "boolean true" ]; then
		/opt/kbd-backlight.sh dim
	elif [ "$x" == "boolean false" ]; then
		/opt/kbd-backlight.sh
	fi
	sleep 1
done )

z-70-kbd-backlight

#!/bin/sh
# Restore keyboard backlight brightness on resume from suspend.
# The only reason this file has a "z-" prefix on Github is to make it appear below kbd-backlight.sh.
# sudo curl -fL -o /etc/pm/sleep.d/70-kbd-backlight https://gist.githubusercontent.com/stefansundin/7003429/raw/z-70-kbd-backlight

USER=username #EDIT THIS
case "$1" in
	resume|thaw)
		su $USER -c "/opt/kbd-backlight.sh fade"&
		;;
esac