On Mon, Nov 9, 2009 at 3:03 PM, John Mendenhall <j...@surfutopia.net> wrote:
>> The mystery to me is why the error message does not appear >> when the pipe is run on a tty. (I can duplicate your error easily). >> >> To me this looks like normal operation. You seem to be getting >> the output you want, right? > > Yup. So, I guess I can just throw away the standard error, to > clean it up a bit. Definitely not a real issue. Just a curiosity > that I like solving. I was just wondering why it runs differently > in different environments. Well, output in sort(3) is through a macro, sort.h: if (!fwrite(ptr, size, n, f)) \ sort.h: err(2, "fwrite"); \ There's no funny business with isatty(). It might have to do with buffering, different buffer size in each case? That's a shot in the dark. Timing? I really don't know. (But I am, like you, curious.) I can't imagine the source for err(3) making a decision, so this must be buried in stdio source for fwrite. Maybe even in the shell that set up the pipe in the first place. Maybe in a system call... Maybe in the lunar phase... Anyway 2>/dev/null can work wonders for this sort of thing. Dave
