Linux Battery Watcher

#!/bin/bash

DIR="/sys/class/power_supply/BAT0"

for PREFIX in "charge" "energy"
do
  if [ -f "$DIR/${PREFIX}_now" ] && [ -f "$DIR/${PREFIX}_full" ]
  then
      echo "$DIR/${PREFIX}_now"
      echo "$DIR/${PREFIX}_full_design"
      for i in 0 2 3 4 5 6 7 8 9
      do
       for j in 0 1 2 3
       do
	REMAIN=$(cat "$DIR/${PREFIX}_now")
	FULL=$(cat "$DIR/${PREFIX}_full_design")
	PRCT=$((100 * $REMAIN / $FULL))
	STATUS=$(cat "$DIR/status")

	echo $REMAIN
	echo $FULL
	echo $STATUS
	echo $PRCT
	if [[ $PRCT -lt 15  &&  "$STATUS" == "Discharging" ]] || [[ $PRCT -gt 80 && "$STATUS" != "Discharging" ]]
	then
	    /usr/bin/mplayer --quiet -ao pulse -loop 2 /home/work/Downloads/alert.mp3
            sleep 5
	fi
       done
      done
  fi
done