gistfile1.sh

#!/bin/bash

NODE1="ec2-blah1.compute-1.amazonaws.com"
NODE2="ec2-blah2.compute-1.amazonaws.com"
NODE3="ec2-blah3.compute-1.amazonaws.com"
NODE4="ec2-blah4.compute-1.amazonaws.com"

    while [ $# -gt 0 ]; do
        case "$1" in
            "1")
              NODE=$NODE1
              ;;
            "2")
              NODE=$NODE2
              ;;
            "3")
              NODE=$NODE3
              ;;
            "4")
              NODE=$NODE4
              ;;
            *)
              echo "Unknown option: $1" >&2;
              exit
              ;;
        esac
    done

echo $NODE

CMD = 'ssh -i ~/.ec2/keypair.pem user@$NODE'
echo $CMD