get IP numbers of instances behind an AWS ELB

elb-instance-ips.sh

#!/bin/bash
display_usage() { 
  echo -e "\nUsage:\n$0 <load-balancer-name> [<region>] \n" 
  }

if [  $# -lt 1 ] 
then 
    display_usage
    exit 1
fi 

for i in `aws --region ${2-us-west-2} elb describe-instance-health --load-balancer-name $1 | grep -i instanceid  | awk '{ print $2}' | cut -d',' -f1| sed -e 's/"//g'`
do
aws --region ${2-us-west-2} ec2 describe-instances --instance-ids $i | grep -i PrivateIpAddress | awk '{ print $2 }' | head -1 | cut -d"," -f1
done;