The only safe way that I could imagine doing this would be to have a chroot jail in which to execute the script, as well as having the process launched by another process that would monitor if it did anything suspect, such as not exiting within a certain amount of time, using an obscene amount of memory, etc. This might be doable, but probably not worth the trouble. Defining the parameters of sanity would be very difficult, and would probably result in breaking lots of benign scripts. It's a nice idea, but not terribly practical. We'll just have to rely on people being decent because they want to be, not because we have a shotgun in our living room, or bars on our windows. ;-)