To submit a dynamic dns update request from shell. https://www.noip.com/ (To update IP of HOSTNAME, update will happen instantly)

nouip.sh

# {NO,Updatemy}IP
# https://www.noip.com/integrate/request

nouip ()
{
    USER=""
    PASSWORD=""
    HOSTNAME=""
    IP=""

    for i in "$@"
    do
        case $i in
            -u=*|--user=*)
            USER="${i#*=}"
            ;;
            -p=*|--password=*)
            PASSWORD="${i#*=}"
            ;;
            -pf=*|--passwdfile=*)
            PASSWORD="$(cat ${i#*=})"
            ;;
            -h=*|--hostname=*)
            HOSTNAME="${i#*=}"
            ;;
            -i=*|--ip=*)
            IP="${i#*=}"
            ;;
            *)
            ;;
        esac
    done

    if [ -z "$USER" ]
    then
        read -p 'Username : ' USER
    fi
    if [ -z "$PASSWORD" ]
    then
        read -sp 'Password : ' PASSWORD
        echo
    fi
    if [ -z "$HOSTNAME" ]
    then
        read -p 'Hostname : ' HOSTNAME
    fi
    if [ -z "$IP" ]
    then
        read -p 'IP : ' IP
    fi

    USERAGENT="--user-agent=\"nouip-shell-script-curl/1.0 nkpro2000sr@gist.github.com\""

    NOIPURL="https://$USER:$PASSWORD@dynupdate.no-ip.com/nic/update?hostname=$HOSTNAME&myip=$IP"

    RESULT=$(curl --user-agent $NOIPUSERAGENT --silent $NOIPURL)
    echo $? $RESULT
}

OR DuckDNS https://www.duckdns.org/spec.jsp

➕ Don't need to confirm your host-names every month as you have to with no-ip.
➕ Free 5 host-names instead of only 3 in no-ip.
➖ ???