ctrl-alt-del in serial console

Glen Turner glen.turner at aarnet.edu.au
Tue Jan 14 23:34:01 CST 2003


Darren wrote:
> I have several PE1650s with serial consoles attached.  According to the
> docs, I should be able to send it an <ESC>R<ESC>r<ESC>R over the serial
> line to deliver a ctrl-alt-del.  Has anyone been able to get this to work?
> 
> My escape key seems to do the correct thing in this terminal as <ESC>2
> simulates the <F2> key, but I've not been able to get the c-a-d sequence
> to work once.

I'm guessing here...

I'd say that the "Esc R Esc r Esc R" is caught by the BIOS
(assuming you've got it configured for serial console).  Once
Linux starts it takes full control of the flow of data from
the serial port and the BIOS doesn't get a look in.

As Zeki pointed out the, the "magic SysRq key" for a
serial console is the RS-232 Break key.  You'll need
to have this enabled, this can be done interactively
with
    sysctl -w 'kernel.sysrq=0'

See
    <http://www.tldp.org/HOWTO/Remote-Serial-Console-HOWTO/security-sysrq.html>
for more detail (noting that this section talks about turning
*off* the Magic SysRq key, so you'll need to substitute '1' where
'0' is used).

Once you've got the "magic SysRq key" working see
    /usr/src/linux/Documentation/sysrq.txt
for the useful keystrokes.

You might want to consider the "power switches" made by various
companies.  Some models have inbuilt modems and terminal servers.

Please let me know how you go, and if the Remote Serial Console
HOWTO needs amendment in light of your expereinces.

Regards,
Glen




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