Automatically find GLX capable display and run vglrun with it. Useful for multiseat with one powerful GPU. Assumes displays are accessible by all users

vglrun_auto

#!/bin/bash
# This script is intended to be used as a replacement for vglrun -d ? program - the display is auto selected
# it can also be included in a game launcher script to automatically get virtualgl if needed and fix LD_PRELOAD order issues with Steam games

# if you have a preffered GPU put name here as it appears on glxinfo renderer string - a partial string is fine if it matches more than one
# GPU the result will be randomly selected
PREFFERED_CARD="GTX 650 Ti"

# ------------------------------------------------------------------------------------------------------------------------------------
# This portion of the script checks libdlfaker.so and libvglfaker.so are at the END of the LD_PRELOAD string
LD_PRELOAD=$(echo ${LD_PRELOAD//libdlfaker.so/} | awk '{$1=$1};1')":libdlfaker.so"
LD_PRELOAD=$(echo ${LD_PRELOAD//libvglfaker.so/} | awk '{$1=$1};1')":libvglfaker.so"

# ------------------------------------------------------------------------------------------------------------------------------------
# This portion of the script checks if glx is suported on the DISPLAY and if not tries to re-invoke the script with vglrun and 

# an auto-selected GPU (designed for this script to be included in bash script with source ) - if an argument was supplied that is executed

#try glxinfo on current DISPLAY - if it fails begin process of setting up VirtualGL
if [ "$( glxinfo 2>&1 | grep "Error:" )" != "" ] && [ "$VGL_ISACTIVE" != 1 ]; then
	echo "GLX not found on display $DISPLAY - setting up VirtualGL" 1>&2
	
	# Get a list of sessions from loginctl - filtered to ones with a DISPLAY set then filter DISPLAY number
	DISPLAYS=$(loginctl list-sessions | grep -v "SESSION" | grep -v "listed" | tr -s " " | sed '/^$/d' | cut -d " " -f2 | xargs loginctl show-session | grep "Display=" | cut -d "=" -f 2)

	# Iterate found list of DISPLAYS - attempt to determine which are GLX capable, add them to the GLX_DISPLAYS list when found
	GLX_DISPLAYS=""
	FOUND_PREFERRED=""
	for CUR_DISPLAY in $DISPLAYS; do
		if [ "$( DISPLAY=$CUR_DISPLAY glxinfo 2>&1 | grep "Error:" )" = "" ]; then
			GPU_NAME="$(DISPLAY=$CUR_DISPLAY glxinfo -B | grep "OpenGL renderer string" | cut -d ":" -f2 | cut -d " " -f2-10000)"
			if [ "$(echo "$GPU_NAME" | grep "$PREFFERED_CARD")" != "" ]; then
				echo "Found preferred card $GPU_NAME on $CUR_DISPLAY" 1>&2
				GLX_DISPLAYS="$GLX_DISPLAYS$CUR_DISPLAY "
				FOUND_PREFERRED="$FOUND_PREFERRED$CUR_DISPLAY"
			else
				echo "Found $GPU_NAME on $CUR_DISPLAY" 1>&2
			fi
			GLX_DISPLAYS="$GLX_DISPLAYS$CUR_DISPLAY "
		fi
	done

	# if preffered card(s) were found use them instead of full list
	if [ "$FOUND_PREFERRED" != "" ]; then GLX_DISPLAYS="$FOUND_PREFERRED"; fi

	# If nothing found apologise - else get to picking a DISPLAY to use
	if [ "$GLX_DISPLAYS" = "" ]; then
		echo "Error: Did not find a GLX display from loginctl" 1>&2
		GLX_DISPLAY_FOUND=0
	else
		# pick care from resulting list
		GLX_DISPLAY="$(printf "%s\n" $GLX_DISPLAYS  | sort -R | xargs echo | head -n 1)"
		GLX_DISPLAY_FOUND=1
	fi
 

	# Setup VirtualGL
	if [ $GLX_DISPLAY_FOUND -gt 0 ]; then
		GPU_NAME="$(DISPLAY=$GLX_DISPLAY glxinfo -B | grep "OpenGL renderer string" | cut -d ":" -f2 | cut -d " " -f2-10000)"
		echo "Using $GPU_NAME on $GLX_DISPLAY for VirtualGL" 1>&2
		if [ -z "$1" ]; then
			vglrun -d $GLX_DISPLAY $0
		else
			vglrun -d $GLX_DISPLAY $1
		fi
	fi	
fi