Battery overcharge notification script for my ThinkPad X220 under Arch Linux

charge_notify.sh

#!/bin/sh -eu
# Battery overcharge notification script for my ThinkPad X220 under Arch Linux
# most ideas and codes are from
# https://linoxide.com/linux-how-to/remind-unplug-charging-laptop-arch-linux/
# thanx

MAX_BAT=70
MIN_BAT=40

BAT_DEV="/org/freedesktop/UPower/devices/battery_BAT0"
SHOW_POWER_INFO_CMD="upower --show-info ${BAT_DEV}"

GET_PERCENTAGE='s/^ *percentage: *\([0-9]*\)%/\1/p'
GET_CHARGE_OR_DISCHARGE='s/^ *state: *\([^ ]*charging\)/\1/p'

LAST_STATE=""
INITIAL_PERCENTAGE=""
LAST_PERCENTAGE=""
PROGRESS_BAR=""

while true; do

    BAT_PERCENTAGE=`${SHOW_POWER_INFO_CMD}|sed -n "${GET_PERCENTAGE}"`
    if [ "$LAST_PERCENTAGE" = "$BAT_PERCENTAGE" ]; then
        PROGRESS_BAR=${PROGRESS_BAR}"#"
    else
        echo -ne "\n"
        LAST_PERCENTAGE=$BAT_PERCENTAGE
        PROGRESS_BAR=""
    fi

    BAT_STATE=`${SHOW_POWER_INFO_CMD}|sed -n "${GET_CHARGE_OR_DISCHARGE}"`
    if [ "$LAST_STATE" != "$BAT_STATE" ]; then
        echo -ne "\n"
        LAST_STATE=$BAT_STATE
        INITIAL_PERCENTAGE=$BAT_PERCENTAGE
        LAST_PERCENTAGE=$BAT_PERCENTAGE
        PROGRESS_BAR=""
    fi

    if [ "$BAT_STATE" = "discharging" ]; then
        echo -ne "\rBattery discharging: "

        if [ $BAT_PERCENTAGE -le $MIN_BAT ]; then
            notify-send "Battery under $MIN_BAT. Plaese plug in the adapter"
        fi
    else
        echo -ne "\rBattery charging: "

        if [ $BAT_PERCENTAGE -ge $MAX_BAT ]; then
            notify-send "Battery above $MAX_BAT. Please remove the adapter"
        fi
    fi

    echo -n "${INITIAL_PERCENTAGE}% -> ${BAT_PERCENTAGE}% ${PROGRESS_BAR}"

    LAST_PERCENTAGE=$BAT_PERCENTAGE

    sleep 10 #Repeat every 10 seconds

done