/tmp is
typically but not
always a tmpfs mount. Presumptions about where files are or aren't actually written to disk given modern virtual memory is ... somewhat fraught.
It also happens that my /tmp is physically allocated.
And named pipes really and truly work differently (though there can still be buffering).
That said, no joy (though I tracked down the issue above -- configfile setting conflicting with commandline parameters, somewhat annoyingly).
