Simple critical battery level warning script

Question

This is a little script I wrote for use on my laptop.  I wanted to have some kind of visual cue to let me know when the battery charge gets below a certain level and this is what I came up with:
#!/bin/bash
# Configuration
interval=120 #in seconds
critical_level=10 #percent
icon="/usr/share/icons/Tango/48x48/devices/battery.png" #notification icon
battery_id="BAT1" #ACPI battery identifier
ac_adapter_id="ADP1" #ACPI power adapter identifier
while true
do
if [ "$(cat /proc/acpi/ac_adapter/$ac_adapter_id/state | grep -o off)" == "off" ]; then
battery_max=`cat /proc/acpi/battery/$battery_id/info | head -3 | tail -1 | awk '{print $4}'`
battery_current=`cat /proc/acpi/battery/$battery_id/state | head -5 | tail -1 | awk '{print $3}'`
battery_level=$((100*$battery_current/$battery_max))
[ $battery_level -le $critical_level ] && \
notify-send -u critical -i "$icon" -t 15000 \
"Battery level is low!" "Only $battery_level% of the charge remains."
fi
sleep $interval
done
This script uses notification-daemon (or notification-daemon-xfce) package.  It can be configured by editing values in the "Configuration" section.  I just autostart it with my openbox session.  It all should be pretty self-explanatory otherwise. 
I hope someone finds it useful.
EDIT: Some improvements to the script.
Last edited by fwojciec (2008-07-09 13:11:14)

Answer 1

robmaloy wrote:
thx, really cool i always forget to look after my battery percentage
maybe you can replace "BAT1" and "ADP1" with variables, so configuration would be easier
Thanks   I made changes according to your suggestion.
moljac024 wrote:laptop-mode tools has an option of running commands when battery charge reaches a certain level. You could just run notify-send from there.
You mean in the auto-hibernate section?  I use it as it was supposed to be used -- for hibernating -- and I think you can only set one command that's executed according to a specified battery level in laptop-mode-tools.  Plus it would be sort of complicated, since displaying the notification depends on two conditions in this script -- specified battery level and power cord being disconnected.