Wait till online

#!/bin/bash

HOST=$1 # Resolvable host name or IP address of remote host.
TIMEOUT=$2

wait_for_host() {
    cnt=0
    host=$1
    status=up
    timeout=$2

    ping -c 1 -n -w 1 $host | grep "1 received" > /dev/null
    result=$?
    [ $result != 0 ] && status=down

    echo
    echo -n "Waiting for host \"$host\" to come back online: "

    while true; do
        ping -c 1 -n -w 1 $host | grep "0 received" > /dev/null
        result=$?

        echo -n "."
        [ $result == 1 ] && { sleep 1; cnt=$((cnt+1)); }


        if [ $result == 1 ] && [ status == "up" ]; then
            continue
        elif [ $result == 0 ]; then
            status=down
        fi

        [ $result == 1 ] && [ $status == "down" ] && {
            sleep 1
            echo -e "\nHost \"$host\" is back online."
            break
        }

        if [ $cnt -ge $timeout ]; then
            echo -e "\nRemote host \"$host\" did not reboot.\n"
            break
        fi
    done
}

echo
ssh root@$HOST reboot

wait_for_host $HOST $TIMEOUT