List<HostNamePair> hostNamePairs = getHostNamesPairsFromFile(hostNamesFile);
for(HostNamePair hostNamePair: hostNamePairs)
hostNames.add(hostNamePair.getExternalHostName());
ec2Connection.deleteInstancesByHostName(hostNames);
}
if(instancesFile != null) {
List<String> instanceIds = FileUtils.readLines(instancesFile);
ec2Connection.deleteInstancesByInstanceId(instanceIds);