ratpoison low battery alert

.bashrc

function ratbatalert ()
{
    # low battery alert for ratpoison
    while true;
    do
        batt=$(upower -e|grep BAT0)
        string_percent=$(upower -i $batt|grep  'percent')
        percent=$(sed "s,percentage: ,," <<< $string_percent)
        number=${percent::-1}
        state=$(upower -i $batt|grep 'state')
        sta=$(sed "s,state: ,," <<< $state)
        state=`tr '[:lower:]' '[:upper:]' <<< ${sta::3}`

        if (($number < $1 )); then
            ratpoison -c "echo $state:BatLow:$number ";
        fi  
        sleep 1
    done

}