How can I detect when an external monitor is connected in linux?
I need to run various scripts to set up my workspace.
Is there some clever way to kick off a script when the monitor state has changed?
I'm using the Nvidia display driver.
There are a set of tools called read-edid that can parse extended display identification data (EDID). If your external monitor is actually detected by these tools, you might be able to periodically check for detection and use the output to start scripts, etc.
You didn't mention though whether you need to do this regardless of whether X was running.
You should use udev
events... a possible rule might look like:
KERNEL=="card0", SUBSYSTEM=="drm", ENV{DISPLAY}=":0", ENV{XAUTHORITY}="/home/ninette/.Xauthority", RUN+="/usr/local/bin/0x_hw_hotplug_monitor.sh"
(Source https://bbs.archlinux.org/viewtopic.php?pid=1329375#p1329375)
I was looking for the same answer :/
I'm using disper (http://willem.engen.nl/projects/disper) and gconftool to enable/disable my second monitor together with a second gnome-panel on it.
disper -l lists all connected monitors, so you could poll that as a last resort.
# only primary display
disper -s
gconftool-2 --type int --set /apps/panel/toplevels/panel_1/screen -- -1
# dual display (nvidia twinview)
disper -e
gconftool-2 --type int --set /apps/panel/toplevels/panel_1/screen 0
killall gnome-panel
Given that, as of 270.18, the nVidia binary drivers still don't seem to implement modern XRandR, you may just have to go with new123456's suggestion to poll a tool like xrandr
for changes in screen size.
On my system, I have yet to find a way to make nVidia properly announce to xrandr
that I have two 1280x1024 monitors, rather than a single 2560x1024 one... which, as you can guess, makes fullscreen games center across both monitors when I forbid them from changing the resolution. (It mucks up my desktop stickies)
xrandr
every couple seconds, and runs the script(s) if it notices a difference.