[GTALUG] Headless laptop - controlling X settings

Giles Orr gilesorr at gmail.com
Mon Jan 25 20:38:00 UTC 2016

I have an old laptop (an Acer Travelmate 270 to be exact) that has no
screen.  The screen busted years ago, and I simply removed it.  This
wasn't a big problem until a couple days ago: I'd hook it up to an
external screen via the VGA out, and everything was fine.  But a
couple days ago, I upgraded from Debian wheezy to Debian jessie, and
after the upgrade the external monitor now claims the provided signal
is "Out of Range."  This doesn't appear to be the same as "No signal"
because after several minutes it switches off (about when the screen
blanking would kick in) and pressing a keyboard button brings back the
"Out of Range" signal.  I can ssh into the machine, so there's an
option to fix it.  I could potentially install Ubuntu or re-install
wheezy, but I'd prefer to fix this if possible.  How do I tell X to
detect and use the monitor over the external VGA connector - and only
that connector, ignoring the now-missing internal screen candidate?
And failing that, how can I force 1024x768 (which is what was working
fine with wheezy) with mirroring across both outputs?


P.S. I was clever enough to try ssh with X-forwarding and then running
arandr and eventually xrandr, but they work with the X server they can
talk to ... which is your local machine, not the remote you've sshed
into.  Even had that worked, I wouldn't know what settings to put into
what file: it was bad enough back in the days of editing
/etc/X11/Xorg.conf by hand, but it's now been replaced by a twisty
maze of start-up scripts that are supposed to detect everything for
you that mostly work but which have remained stubbornly opaque to me
when they fail ...

gilesorr at gmail.com

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