#!/bin/sh
# Scan all output of all video cards known to Linux Direct Rendering Manager
# and identify connected displays.

set -e
exit_code=0
for a in /sys/class/drm/card*-* ; do
	if [ -f $a/edid ] ; then
		# This is tricky: for disconnected outputs, the edid file exists,
		# but it is empty. Monitors in stand-by mode have the "enabled"
		# attribute set to "disabled", but the edid file is still valid.
		# Since the file is purely virtual, we need to copy it first.
		x=$(mktemp)
		cp $a/edid $x
		if [ -s $x ] ; then
			echo "### $(basename $a) ###"
			echo
			edid <$x || exit_code=1
			echo
		fi
		rm -f $x
	fi
done
exit $exit_code