[RodgerTheGreat]

Even if you can be bothered to semi-manually audit the changes a script applies to the VM and can afford the time and space overheads of such a "guess-and-check" approach, a malicious server could send you a different script the second time you requested it, or the script could in turn pull down other payloads differently the second time it executed. If you try to extract a diff of the changes applied to the VM and then reapply it to your host machine to ensure the behavior is the same, why not simply have an installer system which behaves in a more restricted way to begin with? The root of the problem is that shell scripts fetched from remote servers are far too flexible to be 'safe'.