,monitor-setup

#!/bin/bash

# I run 3 displays across 2 video adapters. Getting them all to work as I want (one of them is generally powered down, but not disconnected) was a struggle, but now works flawlessly and I tend to forget about the work involved.
# 
# The key things I needed to find out:
# 
#    1. figuring out how to run a script when a display was connected or disconnected. This needed to be in a udev .rules file somewhere
# 
#        ACTION=="change", SUBSYSTEM=="drm", ENV{HOTPLUG}=="1", RUN+="/usr/local/bin/monitor-hotplug.sh"
# 
#   2. how to enumerate all possible video display names:
# 
#         DEVICES=$(find /sys/class/drm/*/status)
# 
#   3. Writing the rest of the script.
# 
# The last step is mostly left as an exercise for the reader. There are some good examples online; I'll put my current version here https://pastebin.com/V5yGgCbh for a couple of weeks.
 
#Adapt this script to your needs.
 
#
# HINT: use xrandr -q to discover xrandr's device names, which do not map trivially to the device names in /sys/class/drm/*
#
 
DEVICES=$(find /sys/class/drm/*/status)
 
#inspired by /etc/acpd/lid.sh and the function it sources
 
displaynum=`ls /tmp/.X11-unix/* | sed s#/tmp/.X11-unix/X##`
display=":$displaynum.0"
export DISPLAY=":$displaynum.0"
 
# from https://wiki.archlinux.org/index.php/Acpid#Laptop_Monitor_Power_Off
export XAUTHORITY=$(ps -C Xorg -f --no-header | sed -n 's/.*-auth //; s/ -[^ ].*//; p')
 
 
#this while loop declare the $HDMI1 $DVID2 $HDMI2 and others if they are plugged in
while read l
do
  dir=$(dirname $l);
  status=$(cat $l);
  dev=$(echo $dir | cut -d\- -f 2-);
 
  echo "Device: $dev"
  
  if [ $(expr match  $dev "HDMI") != "0" ]
  then
      # REMOVE THE -X- part from HDMI-X-n
      dev=HDMI${dev#HDMI-?-}
  elif [ $(expr match  $dev "DVI") != "0" ]
  then
       # REMOVE THE -X- part from HDMI-X-n
       dev=DVI${dev#DVI-?-}
  else
      dev=$(echo $dev | tr -d '-')
  fi
 
  if [ "connected" == "$status" ]
  then
    echo $dev "connected"
    declare $dev="yes";
 
  fi
done <<< "$DEVICES"
 
logmsg() {
    logger --rfc5424=notq,notime,nohost --msgid MHOT "$*"
}
 
# There are 3 possible monitors:
#
#  HDMI-1 -> right hand 
#  DVI-D-2 -> left hand ASUS monitor
#  HDMI-1-0 -> TV
#
 
if [ -z "$DVI2" -a  -z "$HDMI2" ] ;  then
    #
    # wierd scenario ... ASUS monitors not connected
    #
 
    if [ ! -z "$HDMI1" ] ;  then
    #
    # TV is connected
    #
    logmsg tv no asus
    else
    logmsg no tv no asus
    fi
 
elif [ -z "$DVI2" -a  ! -z "$HDMI2" ] ; then
     # left ASUS connected
     
     if [ ! -z "$HDMI1" ] ; then
     logmsg left and tv
 
     xrandr --setprovideroutputsource 1 0
     xrandr --output HDMI-1 --auto --primary --output HDMI-1-0 --auto --right-of HDMI-2
     logmsg left right with tv
 
     else
     logmsg left
     fi
 
elif [ ! -z "$DVI2" -a  -z "$HDMI2" ] ; then
     # right ASUS connected
 
     if [ ! -z "$HDMI1" ] ; then
     logmsg right
     else
     logmsg right and tv
     fi
 
     
elif [ ! -z "$DVI2" -a  ! -z "$HDMI2" ] ; then
     # both left and right ASUS connected
 
     if [ -z "$HDMI1" ] ; then
     xrandr --output HDMI-1-0 --auto --primary --output DVI-1 --auto --right-of HDMI-1
     logmsg left right no tv
     else
 
     xrandr --setprovideroutputsource 1 0
 
     #xrandr --newmode "1920x1200_60.00"  154.00  1920 1968 2000 2080  1200 1203 1209 1235 +hsync -vsync 
     #xrandr --output DVI-D-2 --mode "1920x1200_60.00"
 
     xrandr --output HDMI-1-0 --auto --output DVI-1 --auto --left-of HDMI-1-0 --output HDMI-1 --primary --auto --left-of DVI-1
     logmsg left right with tv
     fi
 
fi