Bash function for a prompt with visible seconds countdown

readcountdown.sh

# See video: https://youtu.be/5z0JImIiQVs

readcountdown1 is a function
readcountdown1 () 
{ 
    local secs="$1";
    local var="$2";
    local msg="$3";
    local uinp;
    for ((i=secs; i>0; i--))
    do
        unset "$var";
        if ! read -r -n 1 -t 1 -p "$msg (${i}s): " uinp; then
            echo -ne '\r';
        else
            if [[ "$uinp" != '' ]]; then
                echo;
            fi;
            eval "export $var='$uinp'";
            return 0;
        fi;
    done;
    if [[ "$i" -lt 1 ]]; then
        echo;
    fi;
    return 1
}