X screen dimmer toggler - Uses xrandr to toggle between dimming/brightening connected displays

toggle-screen-dimmer.sh

#!/usr/bin/env bash
#####################
# toggle-screen-dimmer.sh - X screen dimmer toggler
# Uses xrandr to toggle between dimming/brightening connected displays
# See --help for usage
# Recommended: create a launcher for this script on the task bar!
#####################

list_displays() {
  xrandr --verbose --current | awk '/ connected/ {print $1}'
}

if [ "$1" == "--list" ]; then
  echo "Available displays:"
  list_displays | sed 's/^/ - /g'
  exit 0
elif [ "$1" == "--help" ]; then
  echo "X screen dimmer toggler"
  echo
  echo "Usage: $0 [--help|--list] [displayname [dim_level]]"
  echo
  echo "Examples:"
  echo
  echo "  List available displays:"
  echo "  $0 --list"
  echo
  echo "  Toggle for all connected displays:"
  echo "  $0"
  echo
  echo "  Toggle for a single display:"
  echo "  $0 eDP-1"
  echo
  echo "  Toggle for a single display with a specific dim level:"
  echo "  $0 eDP-1 0.30"
  exit 1
fi

val_dim="0.30"
if [ -n "$2" ]; then
  if ! echo "$2" | grep -qE '^0(\.[0-9]{2})?$'; then
    echo "Invalid dim level: '$2'. Try: 0.30" >&2
    exit 1
  fi
  val_dim="$2"
fi

val_normal=1

if [ -n "$1" ]; then
  displays="$1"
else
  displays="$(list_displays)"
fi

for display in $displays; do
  curdim="$(xrandr --verbose --current | grep "^$display" -A5 |  awk '/Bright/ {print $2}')"
  
  newval="$val_dim"
  if [ "$curdim" == "$val_dim" ]; then
    newval=$val_normal
  fi
  
  set -x
  xrandr --output "$display" --brightness "$newval"
  { set +x; } 2>/dev/null
done