Get OS X Bluetooth device's battery from the command line

battery.rb

#!/usr/bin/env ruby
require 'plist'

def visit(thing, want, &block)
  case thing
  when Hash
    thing.keys.each do |key|
      if want.include?(key)
        yield key, thing[key]
      else
        visit thing[key], want, &block
      end
    end
  when Array
    thing.each do |value|
      visit value, want, &block
    end
  end
end

plist = Plist::parse_xml(`ioreg -c #{ARGV[0]} -a`)

props = {}
visit plist, ["BatteryPercent", "Product"] do |key, value|
  props[key] ||= value
end

p props

gistfile1.txt

➜  ~  ./battery.rb AppleBluetoothHIDKeyboard
{"BatteryPercent"=>49, "Product"=>"Tatsuhiko Miyagawa’s Keyboard"}
➜  ~  ./battery.rb BNBTrackpadDevice
{"BatteryPercent"=>39, "Product"=>"Tatsuhiko Miyagawa’s Trackpad"}

neat!

I looked man ioreg and found out the way to filter subtrees with "BatteryPercent" keyword.

    $ ioreg -r -d 1 -k BatteryPercent | egrep '("BatteryPercent"|"Product") '
          "Product" = "Masayoshi Sekimura�s Trackpad"
          "BatteryPercent" = 42

Cool, I incorporated that into https://github.com/miyagawa/btbattery

The plist thing is a bit weird since it's an ordered key-value so you have to track state...

👍 https://github.com/miyagawa/btbattery