On Tue, May 01, 2001 at 05:06:47PM +0000,
Bart Schaefer <schaefer@candle.brasslantern.com> wrote:
> 
> On May 1, 11:48am, Thomas wrote:
> } Subject: zsh on serial line?
> }
> } I have a digital VT510 which I connected to my PC's second serial port,
> } /dev/ttyS1, and on the linux box, I started "mgetty -r /dev/ttyS1".
> }[...]
> } [snipped lots of syscalls]
> } readlink("/proc/self/fd/0", "/dev/ttyS1", 4095) = 10
> } open("/dev/ttyS1", O_RDWR|O_NOCTTY|0x8000
> } 
> } Uhm. It stops when trying to open /dev/ttyS1 - what is it waiting for?
> 
> It must be this code in init.c:
> 
>     /* Make sure the tty is opened read/write. */
>     if (isatty(0)) {
>         zsfree(ttystrname);
>         if ((ttystrname = ztrdup(ttyname(0)))) {
>             SHTTY = movefd(open(ttystrname, O_RDWR | O_NOCTTY));
> 
> The kernel probably thinks that ttyS1 is a modem line and is imposing the
> "two-device / kernel-locking scheme" mentioned under the -b option in the
> mgetty manual page.

Good point.

> } How can I change that?
> 
> Try using "setserial ^session_lockout ^pgrp_lockout" on the line, but I've
> never actually done that so I don't know if it will make any difference.

Well, setserial doesn't like "^pgrp_lockout", but "^session_lockout"
seems to help in that I can interrupt the zsh using ^C - but that ends
the zsh session which is not exactly what I want :)

Uhm... the trick is not even that complicated: Just use /sbin/getty
instead of /sbin/mgetty - voila, all works like a charm :-)

Now guess why it's called m(odem)getty and not vtgetty :)

Thanks,
Thomas

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