On Wednesday, 13 March 2019 13:55:25 GMT Ralph Corderoy wrote:
> I've just read that. If you've TCP/IP to each Pi then I'd ditch the
> idea of a physical screen, no matter how small, and use your laptop's,
> etc.
Yes. That's what we've been doing for the past two years or more, but only
with SSH and
FTP.
> By console, is the kernel's ring buffer of messages good enough?
> Displayed by dmesg(1), you can look at what was placed in it on booting,
> once networking is going and you can log in, with `dmesg -Hx'. That
> will pipe to less and you might need to type `-R' to show the colours,
> depending on your settings.
>
> dmesg also has `-w' to wait for new logging in the ring buffer, so a bit
> like `tail -f' that follows a file.
That's useful to know, but see below.
> You need to set up your installation to log to the serial port and not
> run `getty' on it so no login prompt is displayed. The former is common
> on Pis if they want to use that port to talk to another device.
I've been looking into my use of the serial port and have realised that it
wasn't as bad as I
thought it was. If I can solve one remaining problem, I think it will do what
I want it to.
When I first started playing with this, I wasn't sure what serial comms package
to use to
access the screen messages. After searching through quite a few pages and what
packages were available on this machine, settled on PuTTY. This was the cause
of my
confusion, because all it did was put up loads of unprintable chars before it
stopped. If I
then hit CR a few times, i was able to log in.
Today, I looked into this again and tried a few other packages; CuteCom and
moserial
initially. CuteCom seems to work, but I don't really like the layout. I never
really got
moserial to work so I looked around again and discovered minicom. This gives
me all of
the boot messages and does so in a standard Linux console format, so it is
familiar
territory. The only trouble was that it was not seeing keyboard entry, but
that was fixed by
turning off hardware Flow Control.
So the only thing left is to turn off getty. I had a rummage around on line
and found lots
of old pages that talked about disabling it in initab, which no longer exists
on Raspbian
Stretch. I then found references to issuing:
sudo systemctl disable serial-getty@ttyAMA0.service
but it doesn't seem to work, I still get the login prompt.
Any ideas? If I can stop the login prompt from coming up, it may well do
everything I
need.
--
Terry Coles
--
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