Re: Modem /dev/cua vs /dev/ttyS (The Long, True answer to this reappearing question)

[Carey Evans <c.evans@clear.net.nz>]

Steve Hsieh <steveh@eecs.umich.edu> writes:

> No difference.  Does it work on your modem port?
> 
> raindrop:~> stty 115200 echoe -echo -clocal raw < /dev/ttyS0
> raindrop:~> stty 115200 echoe -echo -clocal raw < /dev/ttyS0

It won't ever work because the shell tries to open /dev/ttyS0 without
O_NONBLOCK being one of the flags, and in this case it will wait for
carrier detect before the open() returns.

A small program to open the device with O_NONBLOCK and set CLOCAL
before passing control to the original command could be useful.  I'll
see if I have some spare time to work on it.

You could also open the file with NONBLOCK set in expect (see "man
3tcl open"):

    set tty [open /dev/ttyS0 {RDONLY NONBLOCK}]
    exec stty 115200 -echoe -echo raw <@ $tty
    close $tty

-- 
	 Carey Evans  http://home.clear.net.nz/pages/c.evans/

	  GNU GPL: "The Source will be with you... always."


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