#!/bin/bash
# backlight.sh
# reldate 02dec2011

#  A bug in Fedora Core 16/17 messes up the keyboard backlight controls.
#  This script is a quick-n-dirty workaround, essentially a shell wrapper
#+ for xrandr. It gives more control than on-screen sliders and widgets.

OUTPUT=$(xrandr | grep LV | awk '{print $1}')   # Get display name!
INCR=.05      # For finer-grained control, set INCR to .03 or .02.

old_brightness=$(xrandr --verbose | grep rightness | awk '{ print $2 }')


if [ -z "$1" ]
then
  bright=1    # If no command-line arg, set brightness to 1.0 (default).

  else
    if [ "$1" = "+" ]
    then
      bright=$(echo "scale=2; $old_brightness + $INCR" | bc)   # +.05

  else
    if [ "$1" = "-" ]
    then
      bright=$(echo "scale=2; $old_brightness - $INCR" | bc)   # -.05

  else
    if [ "$1" = "#" ]   # Echoes current brightness; does not change it.
    then
      bright=$old_brightness

  else
    if [[ "$1" = "h" || "$1" = "H" ]]
    then
      echo
      echo "Usage:"
      echo "$0 [No args]    Sets/resets brightness to default (1.0)."
      echo "$0 +            Increments brightness by 0.5."
      echo "$0 -            Decrements brightness by 0.5."
      echo "$0 #            Echoes current brightness without changing it."
      echo "$0 N (number)   Sets brightness to N (useful range .7 - 1.2)."
      echo "$0 h [H]        Echoes this help message."
      echo "$0 any-other    Gives xrandr usage message."

      bright=$old_brightness

  else
    bright="$1"

      fi
     fi
    fi
  fi
fi


xrandr --output "$OUTPUT" --brightness "$bright"   # See xrandr manpage.
                                                   # As root!
E_CHANGE0=$?
echo "Current brightness = $bright"

exit $E_CHANGE0


# =========== Or, alternately . . . ==================== #

#!/bin/bash
# backlight2.sh
# reldate 20jun2012

#  A bug in Fedora Core 16/17 messes up the keyboard backlight controls.
#  This is a quick-n-dirty workaround, an alternate to backlight.sh.

target_dir=\
/sys/devices/pci0000:00/0000:00:01.0/0000:01:00.0/backlight/acpi_video0
# Hardware directory.

actual_brightness=$(cat $target_dir/actual_brightness)
max_brightness=$(cat $target_dir/max_brightness)
Brightness=$target_dir/brightness

let "req_brightness = actual_brightness"   # Requested brightness.

if [ "$1" = "-" ]
then     # Decrement brightness 1 notch.
  let "req_brightness = $actual_brightness - 1"
else
  if [ "$1" = "+" ]
  then   # Increment brightness 1 notch.
    let "req_brightness = $actual_brightness + 1"
   fi
fi

if [ $req_brightness -gt $max_brightness ]
then
  req_brightness=$max_brightness
fi   # Do not exceed max. hardware design brightness.

echo

echo "Old brightness = $actual_brightness"
echo "Max brightness = $max_brightness"
echo "Requested brightness = $req_brightness"
echo

# =====================================
echo $req_brightness > $Brightness
# Must be root for this to take effect.
E_CHANGE1=$?   # Successful?
# =====================================

if [ "$?" -eq 0 ]
then
  echo "Changed brightness!"
else
  echo "Failed to change brightness!"
fi

act_brightness=$(cat $Brightness)
echo "Actual brightness = $act_brightness"

scale0=2
sf=100 # Scale factor.
pct=$(echo "scale=$scale0; $act_brightness / $max_brightness * $sf" | bc)
echo "Percentage brightness = $pct%"

exit $E_CHANGE1