Re: How to send a break?

Re: How to send a break?

[Haar János]

"H. Peter Anvin" <hpa@zytor.com> az alábbiakat írta a következo üzenetben
news:e5dacu$v33$1@terminus.zytor.com...
> Followup to:  <01b701c6818d$4bcd37b0$1800a8c0@dcccs>
> By author:    =?iso-8859-2?Q?Haar_J=E1nos?= <djani22@netcenter.hu>
> In newsgroup: linux.dev.kernel
> >
> > 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
> >
>
> You can't use it using echo, however, you can do it using Perl:
>
> perl -e 'use POSIX; tcsendbreak(1,0);' > /dev/ttyS0

Ahh, thats what i am waiting for, thanks! :-)

Works fine!

Thanks,
Janos




>
> -hpa
> -
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Re: How to send a break?

[Haar János]

----- 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

Re: How to send a break?

[Valdis.Kletnieks]

[-- Attachment #1: Type: text/plain, Size: 807 bytes --]

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.....

[-- Attachment #2: Type: application/pgp-signature, Size: 226 bytes --]

Re: How to send a break?

[linux-os (Dick Johnson)]

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?

Cheers,
Dick Johnson
Penguin : Linux version 2.6.16.4 on an i686 machine (5592.73 BogoMips).
New book: http://www.AbominableFirebug.com/
_
\x1a\x04

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Re: How to send a break?

[H. Peter Anvin]

Followup to:  <01b701c6818d$4bcd37b0$1800a8c0@dcccs>
By author:    =?iso-8859-2?Q?Haar_J=E1nos?= <djani22@netcenter.hu>
In newsgroup: linux.dev.kernel
>
> 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
> 

You can't use it using echo, however, you can do it using Perl:

perl -e 'use POSIX; tcsendbreak(1,0);' > /dev/ttyS0

	-hpa

Re: How to send a break?

[Jim Crilly]

On 05/27/06 02:58:44PM +0200, 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
> 

Is there a reason you can't use "echo -n m > /proc/sysrq-trigger"?

Jim.

How to send a break?

[Haar János]

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