stdin and UNIX pipes

[Paul Falstad]

bliss at sp64.csrd.uiuc.edu (Brian Bliss) wrote:
>saying
>
>  fopen ("/dev/tty", "r");
>
>always opens the screen for input, regardless of the state of stdin.
>obvoulsy, somewhere (in libc.a?) there is code to check for the
>string "/dev/tty", and open /dev/tty/tty?? instead of trying
>to open the directory /dev/tty.

Not quite.

1. it opens the _tty_ for input, _if_ your process has a controlling
terminal.
2. there's no such directory /dev/tty.  At least not on my system.
It might have been a good idea, but a tad unportable since /dev/tty
already exists.
3. the /dev/tty -> /dev/tty?? is done in the kernel by checking
minor device numbers, not strings.  It is not in libc; typing
open("/dev/tty",2) opens a tty without touching any libraries
(except for the actual trap code, of course).

I'd redirect followups to a more appropriate group, like
comp.unix.programmer, but I don't want them there either.  :-)

--
  Paul Falstad, pfalstad at phoenix.princeton.edu PLink:HYPNOS GEnie:P.FALSTAD
  I think there should be more race prejudice.  <slap> LESS race prejudice.
     Princeton University apologizes for the content of this article.