Simple Bash script that reads macOS accessory battery levels via pmset and publishes them to Home Assistant using MQTT discovery

ha_devices_battery.sh

#!/usr/bin/env bash
set -euo pipefail

broker_host="${BROKER_HOST:-192.168.0.123}"; broker_port="${BROKER_PORT:-1883}"
mqtt_user="${MQTT_USER:-mqtt-user}"; mqtt_pass="${MQTT_PASS:-$(cat "$HOME/.mqtt_pass")}"
discovery_prefix="${DISC_PREFIX:-homeassistant}"; state_base="${STATE_BASE:-macos/accps}"

publish_args=(-h "$broker_host" -p "$broker_port"); [[ -n "$mqtt_user" ]] && publish_args+=(-u "$mqtt_user" -P "$mqtt_pass")
slug(){ echo "$1" | tr '[:upper:]' '[:lower:]' | sed -E 's/[^a-z0-9]+/_/g;s/_+/_/g;s/^_//;s/_$//'; }

pmset -g accps 2>/dev/null | sed -nE 's/^[[:space:]]*-//p' | while IFS= read -r line; do
  device_name="$(echo "$line" | sed -E 's/[[:space:]]*\(id=.*$//')"
  # Only used to provide a unique device identifier in Home Assistant.
  device_id="uniqueid1234"
  battery_percent="$(echo "$line" | sed -nE 's/.*[^0-9]([0-9]{1,3})%.*/\1/p')"
  [[ -z "${device_id:-}" || -z "${battery_percent:-}" ]] && continue
  device_key="$(slug "${device_name}_${device_id}")"
  config_topic="$discovery_prefix/sensor/$device_key/battery/config"
  state_topic="$state_base/$device_key/battery"
  payload="{\"name\":\"Battery\",\"state_topic\":\"$state_topic\",\"unit_of_measurement\":\"%\",\"device_class\":\"battery\",\"unique_id\":\"${device_key}_battery\",\"device\":{\"identifiers\":[\"$device_key\"],\"name\":\"$device_name\"}}"
  /opt/homebrew/bin/mosquitto_pub "${publish_args[@]}" -t "$config_topic" -r -m "$payload"
  /opt/homebrew/bin/mosquitto_pub "${publish_args[@]}" -t "$state_topic" -r -m "$battery_percent"
done