#!/bin/sh
+
# A very primitive backlight setter with a hardcoded backlight path, to replace
# xbacklight which currently does not work on my system.
-if ! echo "${1}" | egrep -q '^[0-9]+$'; then
- echo 'Argument must be a number.'
+
+if ! echo "${1}" | egrep -q '^[0-9]+$' && ! [ "${1}" = "+" -o "${1}" = "-" ]; then
+ echo 'Argument must be a number, or "+", or "-".'
exit 1
fi
-percentage=${1}
backlight_dir=/sys/class/backlight/intel_backlight
max_brightness=$(cat "${backlight_dir}"/max_brightness)
+target="${backlight_dir}"/brightness
+fract=$(expr "${max_brightness}" / 100)
+if [ "${1}" = "+" -o "${1}" = "-" ]; then
+ cur_brightness=$(cat "${backlight_dir}"/brightness)
+ brightness=$(expr "${cur_brightness}" "${1}" "${fract}")
+ if [ "${brightness}" -gt "${max_brightness}" ]; then
+ brightness="${max_brightness}"
+ elif [ "${brightness}" -lt "0" ]; then
+ brightness=0
+ fi
+ sudo sh -c 'echo '"${brightness}"' > '"${target}"
+ exit 0
+fi
+percentage=${1}
if [ "${percentage}" = '100' ]; then
- sudo sh -c 'echo '"${max_brightness}"' > '"${backlight_dir}"'/brightness'
+ sudo sh -c 'echo '"${max_brightness}"' > '"${target}"
else
- fract=$(expr "${max_brightness}" / 100)
brightness=$(expr "${percentage}" \* "${fract}")
- sudo sh -c 'echo '"${brightness}"' > '"${backlight_dir}"'/brightness'
+ sudo sh -c 'echo '"${brightness}"' > '"${target}"
fi