bash script to warn you when your battery is low and play sounds when the charging connector is pluggin in/out

batwarn.sh

#!/bin/bash

get_current() {
    bat0=$(cat /sys/class/power_supply/BAT0/capacity)
    bat1=$(cat /sys/class/power_supply/BAT1/capacity)

    echo $bat0 + $bat1 - 5 | bc # -5 because that's what the driver will say when the battery is unusably low
}

warn() {
    charging_status=$(cat /sys/class/power_supply/AC/online)
    last_charging_status=$charging_status

    current=$(get_current)
    last=$(echo $current + 1 | bc)

    while :; do
        # if charging
        if [ $charging_status == "0" ]; then
            if [ $current -lt 15 ]; then
                mplayer ~/.local/share/batwarn/ping.webm
                notify-send batwarn "only $current% left"
                google_speech "only $current% battery charge left"
                sleep 60
            fi
        fi
            

        # do this.
        last=$current
        current=$(get_current)

        last_charging_status=$charging_status
        charging_status=$(cat /sys/class/power_supply/AC/online)

        sleep .1
    done
}

charging() {
    c_charging_status=$(cat /sys/class/power_supply/AC/online)
    c_last_charging_status=$c_charging_status

    while :; do
        # if charging
        if [ "$c_charging_status" != "$c_last_charging_status" ]; then
            if [ "$c_charging_status" == "1" ]; then
                echo connected
                notify-send batwarn "connecting connector connected"
                mpv ~/.local/share/batwarn/charging.ogg >/dev/null &
            elif [ "$c_charging_status" == "0" ]; then
                echo disconnected
                notify-send batwarn "connecting connector disconnected"
                mpv ~/.local/share/batwarn/plugged_out.ogg >/dev/null &
            fi

        fi

        c_last_charging_status="$c_charging_status"
        c_charging_status=$(cat /sys/class/power_supply/AC/online)

        sleep .1
    done
}

charging  &
warn