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Painless

Member

Registered: 2006-02-06

Posts: 234

battery check script

Hi all!  I'm sure this one has been done to death, but with.  It's a script to monitor a laptop battery and react accordingly.  I wrote this for use with FVWM, to send out warning notices using libnotify when the battery gets too low.  Since my laptop is quite old, the battery runs out quite quickly after getting to 25% capacity.  The script backgrounds itself on being run.  It starts when I begin an FVWM session, and I have FVWM kill the script when I logout.

Being a script it's easy to tweak to your particular requirements.  The example below just warns, but it would be easy to have the script suspend or hibernate the system, or change the percentage charge at which the script performs different actions.  I hope it's useful.

#!/bin/bash
#
# battery check script
# ====================
# Designed to be run continuously while WM is running
# Requires libnotify to be installed
#

ICONPATH=/home/rob/.fvwm/icons/24x18
BATDIR=/sys/class/power_supply/BAT0
NOTIFYSEND=/usr/bin/notify-send

if [ ! -x $NOTIFYSEND ]
then
   exit 0
fi

# check every $CHECK seconds
CHECK=60

( while true
do
   BATSTATE=`cat ${BATDIR}/status`
   # Note valid BATSTATE values are: Charged, Charging, and Discharging
   if [ "$BATSTATE" = "Discharging" ]
   then
      REM_CAP=`cat ${BATDIR}/charge_now`
      FULL_CAP=`cat ${BATDIR}/charge_full`
      CHARGE=`echo $(( $REM_CAP * 100 / $FULL_CAP ))`
      if [ "$CHARGE" -lt "25" ]
      then
	 $NOTIFYSEND -i $ICONPATH/battery_critical.png -u critical -t 30000 "battery critical" "Shutdown or connect power now"
	 sleep $CHECK
	 continue
      fi
      if [ "$CHARGE" -lt "30" ]
      then
	 $NOTIFYSEND -i $ICONPATH/battery_low.png -u normal -t 20000 "battery low" "Connect power soon"
      fi
      sleep $CHECK
   elif [ "$BATSTATE" = "Charged" ]
   then
      $NOTIFYSEND -i $ICONPATH/battery_full.png -u normal -t 20000 "battery fully charged" "Disconnect from power"
      sleep $CHECK
   else
      sleep $CHECK
   fi
done
) &

# end of file

Edited 21/10/2011 to use /sys/class/power_supply/BAT0 instead of /proc/acpi/battery/BAT0

Last edited by Painless (2011-10-21 12:48:05)