Bell & ssh

[James Wilkinson]

Bill Gradwohl wrote:
> I want the remote box to beep. I want to understand where the difference 
> is since the echo command executes on the remote machine regardless. How 
> does ssh turn the bell off?

It doesn't. It doesn't turn it *on*.

There are a couple of issues to think about.

One is that normally a shell script will send a beep to the controlling
terminal. Normally, if you have a remote terminal, be it SSH or telnet
or a serial connection, the beep signal will be sent as ASCII 7 to the
terminal in question, since the beep is designed to attract the user's
attention.

Think about a single Unix box in a server room somewhere, with hundreds
of logged-on user sessions over several warehouses, possibly in multiple
countries. A beep would be generated by a process connected to *one*
session, and you'd want that user to hear the beep.

(I've actually just described my workplace, incidentally).

So a beep will be sent as ASCII to the controlling terminal. If you're
logged on locally, then there will be support for the speaker as part of
the terminal emulation.

The other is who owns /dev/console? Under Fedora, this will change
depending on who is logged in there. So if you give permission for a
different user to sound a beep, then Fedora is likely to change those
permissions under you.

Take a look at /etc/security/console.perms to see what you might want to
change. And look at
http://www.redhat.com/docs/manuals/linux/RHL-9-Manual/custom-guide/s1-access-console-files.html

As for getting the right beeper to beep ... I'm not sure. If necessary,
you could try playing around with
http://www.geocities.com/stssppnn/pcsp.html or another PC Speaker
driver...

(I must admit, I can't help you much more, as this box has the beep
firmly turned OFF, and I haven't compiled the driver for this kernel...)

James.

-- 
E-mail address: james | In poker you have to show your hand eventually if
@westexe.demon.co.uk  | called. So far SCO have with great reluctance shown
                      | only one card, which turned out to be "Mr Bun, The
                      | Baker".  -- Electric Dragon on groklaw.net