So he saves his Perl script and stops working on it for now. If he writes it in short bursts, opening it once or twice a day to type in a few lines and then closing it, it’s unlikely that the surveillors will be able to follow what he is up to, even if they happen to be hackers. Just to be an asshole, he modifies his X Windows options in such a way that none of the windows on the screen will have a title bar at the top. That way the surveillance people won’t be able to tell what file he is working on at any given moment, which will make it a lot harder for them to string a long series of observations together into a coherent picture of what’s in his Perl script.