I'm in the process of setting up a laptop running Debian Jesse with xmonad as the display manager. I use xmobar to display information about the current state of the system, including the battery level. However, I find that I forget to check regularly and I'm always surprised when my computer suddenly shuts off because the battery died --- I miss the pop-up notifications that I used to get with XFCE.

What can I use to get an attention-grabbing warning about my low battery? Most solutions I've found use dzen, or just display a number on the status bar, which I've found to be insufficient.


2 Answers 2


This is no ready solution, but an idea: I would use osd_cat which comes in the package xosd in Fedora Linux together with a cronjob, that checks your battery status.

You can edit your cronjobs with

crontab -e

and you find your battery status in /sys/class/power_supply/, and there it is in my case BAT1/ with some files charge_now and charge_full. With those files, that is with


you could find the percentage remaining in your battery, which could then show you a big message with osd_cat (onscreen display).


Here is a short script I wrote following @erik's suggestion of using osd_cat:

from subprocess import Popen, PIPE

with open("/sys/class/power_supply/BAT0/charge_now") as f:
    charge_now = float(f.read())
with open("/sys/class/power_supply/BAT0/charge_full") as f:
    charge_full = float(f.read())

percent = 100*charge_now/charge_full

if percent < 10:
    p = Popen(['osd_cat','-A','center','-p','middle','-f','-*-*-bold-*-*-*-36-120-*-*-*-*-*-*','-cred','-s','5'],stdin=PIPE)
    p.communicate(input="Battery Low!")

which you can then run via a cron job every minute:


* * * * * python ~/power_warning.py

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