Are you suggesting that that might be able to detect a filehandle "gone bad"? My problem is not that the open fails, but that the filehandle goes bad (apparently being closed by the child) some time after opening.

I see now what you mean, my assumption from the "Detect whether a writeable filehandle has closed?" was that you're looking at the filehandle on your end, but you're asking about the other end of the pipe. Sorry, fileno doesn't help with that, only if your filehandle closes (i.e. $pipe in your example here).

You might want to look at IPC::Run, it has a pumpable method that seems more like what you're asking for. I've also used its pump_nb method inside an eval to detect when a child process has gone bad.

Minor edits.