Re: How to send a break?

["Haar János" <djani22@netcenter.hu>]

----- Original Message ----- 
From: <Valdis.Kletnieks@vt.edu>
To: "linux-os (Dick Johnson)" <linux-os@analogic.com>
Cc: "Haar János" <djani22@netcenter.hu>; <linux-kernel@vger.kernel.org>
Sent: Monday, May 29, 2006 5:35 PM
Subject: Re: How to send a break?

On Mon, 29 May 2006 11:08:15 EDT, "linux-os (Dick Johnson)" said:
>
> On Sat, 27 May 2006, [iso-8859-2] Haar János wrote:
>
> > Hello, list,
> >
> > I wish to know, how to send a "BREAK" to trigger the sysreq functions on
the
> > serial line, using echo.
> >
> > I mean like this:
> >
> > #!/bin/bash
> > echo "?BREAK?" >/dev/ttyS0
> > sleep 2
> > echo "m" >/dev/ttyS0
> >
> > Thanks,
> > Janos
> >
>
> Can't you use /proc/sysrq-trigger?

> That can be tricky if the other end of /dev/ttyS0 is plugged into a
debugging
> serial port on an embedded system where you don't have easy access to a
shell.

> Or for that matter, if you're trying to talk to the serial port on a
non-embedded
> system, which is too far into OOM thrashing for you to be able to get a
> usable shell prompt.....

This is for debugging an frozen X86_64 system! :-)

Thanks,
Janos