up

#!/bin/bash

function loop-until-up() {
    until nmap -sn $1 | grep "Host is up" > /dev/null ; do
        sleep 5s
    done
}

function alarm-while-up() {
    while nmap -sn $1 | grep "Host is up" > /dev/null ; do
        printf '\7'
        sleep 2s
    done
}

function main() {
    echo Waiting for $1...
    loop-until-up $1

    echo -n $1 went UP at
    date +" %H:%M, %a, %m/%d/%g"

    alarm-while-up $1

    echo -n $1 went back down at
    date +" %H:%M, %a, %m/%d/%g"
    main $1
}

if [ -z $1 ] ; then
    echo Missing IP address
else
    main $1
fi