FreeBSD Lenovo Thinkpad screen brightness adjustments

acpi_brightness

#!/bin/sh
# /usr/local/bin/acpi_brightness
# Credit: https://www.davidschlachter.com/misc/freebsd-acpi_video-thinkpad-display-brightness

CURRENT_LEVEL=`/sbin/sysctl -n hw.acpi.video.lcd0.brightness`
UP=$1

if [ $UP == 1 ]; then
  for i in 1 2 4 6 9 15 24 36 51 69 90 100; do
    if [ "$CURRENT_LEVEL" -lt "$i" ]; then
      /sbin/sysctl hw.acpi.video.lcd0.brightness=$i
      exit
    fi
  done
fi

if [ $UP == 0 ]; then
  for i in 100 90 69 51 36 24 15 9 6 4 2 1; do
    if [ "$CURRENT_LEVEL" -gt "$i" ]; then
      /sbin/sysctl hw.acpi.video.lcd0.brightness=$i
      exit
    fi
  done
fi

acpi_brightness.conf

# /usr/local/etc/devd/acpi_brightness.conf

notify 20 {
 match "system" "ACPI";
 match "subsystem" "IBM";
 match "notify" "0x10";
 action "/usr/local/bin/acpi_brightness 1";
};
notify 20 {
 match "system" "ACPI";
 match "subsystem" "IBM";
 match "notify" "0x11";
 action "/usr/local/bin/acpi_brightness 0";
};