zpoweralertd

zpoweralertd gives you power notifications as you need them. Paul Allen has mistaken it for poweralertd, which seems logical, because zpoweralertd also depends on UPower and a notification daemon such as mako, and in fact does the same exact thing poweralertd does, and it also has a penchant for D-Bus integration and lightweight code. poweralertd and zpoweralertd even support the same command-line arguments, although zpoweralertd is slightly more modern.

If you couldn't tell by now, zpoweralertd is a Zig rewrite and drop-in replacement of poweralertd.

How to build

zig build

(requires Zig 0.15.1+)

Usage

Simply run zpoweralertd to start receiving desktop notifications about power events like battery state changes, warning levels, and power supply connect/disconnect:

zpoweralertd

In Sway and similar desktop environments, you can copy-paste the following to the end of the configuration file (e.g. ~/.config/sway/config) to automatically launch zpoweralertd in the background:

# zpoweralertd
# https://codeberg.org/mrus/zpoweralertd
exec zpoweralertd

Options

The following flags are available:

Flag	Description
-h	Show help message
-i <device_type>	Ignore a device type (can be specified multiple times)
-s	Ignore events at startup
-S	Only monitor power supplies
-v	Show version number
-V	Verbose output
--when <status> <pct> <command>	Execute a shell command at a specific battery percentage

Almost all flags are the exact same ones supported by poweralertd. However, zpoweralertd also implements flags that poweralertd does not support:

--when

The --when flag allows executing arbitrary shell commands when the battery reaches a specific percentage, either by charging or discharging. This is a feature unique to zpoweralertd and poweralertd does not support it.

The flag takes three arguments:

1. status: Either charged (aliases: charge, charging) or discharged (aliases: discharge, discharging)
2. percentage: The battery level (number from 0 to 100)
3. command: The shell command to execute

For discharged, the command fires when the battery percentage drops to or below the given value. For charged, it fires when the percentage reaches or exceeds it. The command fires once when the condition is met and will only fire again after the condition has cleared and been met again.

The flag can be specified multiple times to define different rules:

zpoweralertd \
  --when discharged 5 "doas halt" \
  --when discharged 15 "notify-send 'Battery critical!'" \
  --when charged 99 "notify-send 'Almost full!'"

This makes it possible to build a complete power management policy directly through command-line arguments, from low-battery warnings to automatic shutdown, without any external scripts or configuration files. The benefit this has over, let's say, udev rules, is that script execution as the current user is significantly easier, less hacky and poses fewer overall security risks, as zpoweralertd does not need to (read: should not) be run in privileged mode.

Footnotes

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