Hibernate on Low Battery, when acpi does not report proper battery status

hibernate-on-low-battery.sh

#!/bin/sh

# Battery threshold below which, script will hibernate if discharging
batt_threshold=20
# temporary file to store the previous battery charge value, to determine if battery is being discharged
batt_charge_file="/tmp/batt_charge"

# read in batt charge from acpi
echo "`acpi -b`, `cat /tmp/batt_charge`%" | awk -F'[:,%]' '{print $2, $3, $5, ($5 - $3), ($3-$5)<0?"discharging":"powered"}' | {
    read -r acpi_status capacity old_capacity capacity_diff status

    logger "$0: ($acpi_status) $status $capacity <= $old_capacity"

    # if ( (capacity - old_capacity) < 0 && capacity < 15 )
    if [ "$status" = discharging ]; then

        #notification 1% before laptop is going to be hibernated
        if [ "$capacity" -lt "$(($batt_threshold + 2))" ]; then
            notify-send "Battery Low" "System will be hibernated soon..." -u CRITICAL
        fi

        if [ "$capacity" -lt "$batt_threshold" ]; then
            logger "$0: Critical battery threshold"
            systemctl hibernate
        fi
    fi

    echo $capacity > $batt_charge_file
}

add to (f)crontab to run every minute or couple of minutes

*/1   *   *   *   *   /opt/scripts/hibernate-on-low-battery.sh 

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