misc/scripts/redshift-i2c

#!/bin/sh

# Set brightness for DDC/CI enabled monitors

export PATH="/var/setuid-wrappers:$PATH"

# monitor i2c device
device=dev:/dev/i2c-0

# brightness values
night=35
transition=45
daytime=60


deref() {
  eval "echo \$$1"
}

set_brightness() {
  sudo ddccontrol $device -r 0x10 -w > /dev/null "$1" 2>&1
}

fade_to() {
  current=$(sudo ddccontrol $device -r 0x10 2> /dev/null | grep -oP '\+/\K[0-9]+')
  [ "$current" -gt "$1" ] && step=-1 || step=1
  for i in $(seq "$current" "$step" "$1"); do
    set_brightness "$i"
    sleep 1
  done
}


if [ "$1" = "period-changed" ]; then
  if ! (lsmod | grep -q "^i2c_dev"); then
    sudo modprobe i2c-dev
  fi
  fade_to "$(deref "$3")"
fi