Which is more portable: stty < or stty >

[Guy Harris]

>The former is the 7th Ed. UNIX and 4BSD behavior.
>System V assumes you may want to redirect the output somewhere other
>than the terminal being probed.

You can do that with the V7 and BSD one, it's just more painful - you
have to redirect the standard error.

The S5 behavior is a bit more natural, in that its output goes to, well,
the standard output; the only reason I can see for the V7 behavior is
that it makes it possible to set the modes on a tty other than one on
which you're logged in without being super-user, since traditionally
ttys have been publicly writable but not publicly readable.

While in some environments this would be considered a feature ("Hey,
Jane, I screwed up my tty settings; could you fix them for me? I'm on
'/dev/tty73'."), it would be considered a problem in others
("stty erase 's' kill 't' intr 'y' >/dev/tty73").

Given that in 4.3BSD and now S5R4 ttys are *not* publicly writeable, but
writeable only by a special group, to which programs like "write" are
set-GID (so that you can't send things like the "transmit screen to
host" escape sequence to somebody else's terminal), the V7 behavior
doesn't buy you anything any more.