batnotifsd — Battery notifications daemon

What

This is a Python script that sends notifications about the battery's status (charger plugged in/unplugged, low/critical battery levels).

It's useful for window managers where you don't get this functionality out of the box like in a desktop environment.

Why

I wrote this because I simply could not find anything else that did the job 100% right. The internet is full of shell scripts that just tap into /sys/class/power_supply and take info from that in a while true loop with a sleep, most don't even autodetect the laptop's battery and they make you set a variable for the right battery for you, or, even worse, manually edit the shell script to put it in.

How

This Python script uses the pydbus library to get information directly from UPower through DBus, and then send it back through DBus using the org.freedesktop.Notifications bus, all in a GLib loop.

Also, it automatically detects the first battery that classifies as a laptop battery¹.

Usage

To start the daemon, simply use:

$ batnotifsd

You probably want to add it to the autostart of your window manager, check with your WM's documentation for that.

Packages

NixOS

A derivation for this package is available inside my Nix package collection. Just follow my-nixpkgs/Usage to add the flake to your config and to add the program to your environment.systemPackages.

Right now I'm the only person actually using this program, so it's only available in the repo with my personal Nix derivations. If there's going to be any interest in it, I'll upstream a derivation into Nixpkgs.

Feel free to just take out the derivation from the pkgs/ folder and stick it in your configuration, if you know what you're doing.

PyPi

This script is available in PyPi here. To install it using pip, run:

$ pip install batnotifsd

About the flake

The Nix flake present in this repo is just the development shell I use to test this script.

More info

• pydbus documentation
• pydbus tutorial (teaches how to actually take values out of DBus)
• pydbus notification example (teaches how to send notifications using DBus)
• org.freedesktop.UPower.device specification in the UPower Manual (teaches what UPower properties are there and what they mean)

1. If the value is set to "Battery", you will need to verify that the property power-supply has the value "true" before considering it as a laptop battery. Otherwise it will likely be the battery for a device of an unknown type. — org.freedesktop.UPower.device specification in the UPower Manual ↩