#!/bin/sh -e
# Automatically set screen brightness based on time of day.
# OLD: value=$(expr 100 - $(expr 13 - $(date +%H) | tr -d -) \* 5)
# S Function: echo "(c($(date +%H) / 4 - 3) + 1) * 50" | bc -l
value=$(echo "l=(100 - 1.5 * ( 11 - $(date +%H) ) ^ 2); if(l > 0) l else 3" | bc -l)
light -S $value
{ date && echo $value; } >>/var/log/autolight