The problem with doing this is you end up with a bunch of tools which may or may not have unexpected behavior depending on how you ran them. It's better to have

The problem with doing this is you end up with a bunch of tools which may or may not have unexpected behavior depending on how you ran them. It's better to have a simple design that just works one way, and you're forced to use it in the one right way. When users invariably use it the wrong way, the reasoning about the failures is simpler, and there are no extra bugs from the extra lines of guard-rail code. If you really wanted to add this 'protection code', you could make a bash wrapper around every Unix command that has its input or output connected to a tty. Not perfect, but it would eliminate a whole lot of extra tty-checking code from every app, providing a single reliable interface. I imagine you'd turn it off after a while, though.