Notify on low battery and hibernate before empty

battery-guard

#!/bin/sh
export DISPLAY=":0"

notice_0=50
warning_0=25
critical_0=10

notice_1=50
warning_1=10

tmpDir="/tmp/battery-guard-nagbar"
mkdir -p "$tmpDir"

function nagbar() {
    type="$1"
    number="$2"
    message="$3"
    showOrClear="${4:-0}" # 0: show, else: clear
    state="$tmpDir/${type}_${number}"

    if [ $showOrClear -eq 0 ]; then
        if [ ! -f $state ]; then
            touch $state
            i3-nagbar -m "$message" -t $type -f "pango:DejaVu Sans Mono 10" 2>&1 1> /dev/null &
        fi
    else
        rm -f $state
    fi
}

while true; do acpi -b | awk -F'[,:%]' '{print $2, $3}' | {
    read -r status_0 capacity_0
    read -r status_1 capacity_1

    test "$status_1" = Discharging -a "$capacity_1" -lt $notice_1
    nagbar warning 1 "External battery is now under $notice_1 % ($capacity_1 %)" $?

    test "$status_1" = Discharging -a "$capacity_1" -lt $warning_1
    nagbar warning 1 "External battery getting low ($capacity_1 %)" $?

    test "$status_0" = Discharging -a "$capacity_0" -lt $notice_0
    nagbar warning 0 "External battery is now under $notice_0 % ($capacity_0 %)" $?

    test "$status_0" = Discharging -a "$capacity_0" -lt $warning_0
    nagbar warning 0 "Internal battery getting low ($capacity_0 %)" $?

    if [ "$status_0" = Discharging -a "$capacity_0" -lt $critical_0 ]; then
        logger "Critical battery threshold ($critical_0 %)"
        nagbar error 1 "Internal battery critically low ($capacity_0 %)"
        systemctl hibernate
    else
        nagbar error 1 clear 1
    fi

    let "total = 1 + ($capacity_0 * 2) + ($capacity_1 * 2)"
    sleep $total
}
done