count down in shell

countdown.sh

function countdown
{
        local SECONDS=$1
        local START=$(date +%s)
        local END=$((START + SECONDS))
        local CUR=$START

        while [[ $CUR -lt $END ]]
        do
                CUR=$(date +%s)
                LEFT=$((END-CUR))

                printf "\r%01d" \
                        $((LEFT%60))

                sleep 1
        done
        echo "        "
}

countdown '5'