Automatically Switch Monitors with Laptop Dock – How to Guide

Dock/UnDock Scripts

I have finally put together a complete script setup that will detect my dock status and switch the monitors automatically.

The first thing I did was to get rid of my Xorg.conf as it caused more issues that it solved. Since I am using an nvdia card I eventually found that using disper was the best way to go. I had discounted it before as its standard commands could not achieve my dualview setup but then I found I could create a custom metamode to use with disper.

To create the custom metamode I used the values stored in Xorg.conf along with previous testing with nv-control-dpy and xrandr as a guide. This metamode and other twinview values were added to a file that can be passed to disper through stdin.

Due to having different sized monitors with Twinview I need to use XCreateMouseVoid, as described in this question.

Below is a complete breakdown of the scripts and files with their contents.

Scripts

1. Create XCreateMouseVoid script:

   Script Name: ~/.mousevoid

   #!/bin/bash
   echo "Mouse Void"
   /opt/XCreateMouseVoid/XCreateMouseVoid 0 1112 1280 88 &
   /opt/XCreateMouseVoid/XCreateMouseVoid 0 0 1280 88 &
   

   chmod +x ~/.mousevoid

2. Create Disper settings file:

   File Name: ~/.disperDocked

   backend: nvidia
   associated displays: CRT-0, DFP-0, DFP-1
   metamode: CRT-0: 1280x1024_60 @1280x1024 +0+88, DFP-1: 1920x1200 @1920x1200 +1280+0
   scaling: default, default, stretched
   xinerama info order: DFP-1, CRT-0, DFP-0
   

3. Create the export dbus session script:

   Script Name: ~/.export_x_info

   #!/bin/bash
   # Export the dbus session address on startup so it can be used by any other environment
   sleep 5
   touch $HOME/.Xdbus
   chmod 600 $HOME/.Xdbus
   env | grep DBUS_SESSION_BUS_ADDRESS > $HOME/.Xdbus
   echo 'export DBUS_SESSION_BUS_ADDRESS' >> $HOME/.Xdbus
   # Export XAUTHORITY value on startup so it can be used by cron
   env | grep XAUTHORITY >> $HOME/.Xdbus
   echo 'export XAUTHORITY' >> $HOME/.Xdbus
   

   Set to user executable only: chmod 700 ~/.export_x_info

   Then put it in Startup Applications:

   Name: X Environment Variables
   Command: /home/your_user/.export_x_info
   

   Unless you restart you need to run ~/.export_x_info to create the .Xdbus file

4. Create the udev rule that will run with upon a dock event:

   Script Name: /etc/udev/rules.d/81-dell-dock.rules

   KERNEL=="dock.0", ACTION=="change", RUN+="/usr/local/sbin/dell-dock"

   chmod +x /etc/udev/rules.d/81-dell-dock.rules

5. Create the script that is associated with the udev rule:

   Script Name: /usr/local/sbin/dell-dock

   #!/bin/sh
   # wait for the dock state to change
   sleep 0.5
   DOCKED=$(cat /sys/devices/platform/dock.0/docked)
   case "$DOCKED" in
      "0")
          echo "Run UnDocking Script..."
           /usr/local/sbin/undock
           ;;
       "1") 
           echo "Run Docking Script..."
           /usr/local/sbin/dock
           ;;
   esac
   exit 0
   

   chmod +x /usr/local/sbin/dell-dock

6. Create the undock script (change your_user to match your user name):

   Script Name: /usr/local/sbin/undock

   #!/bin/bash
   USER=your_user
   export HOME=/home/$USER
   source $HOME/.Xdbus
   export DISPLAY=:0
   echo "UnDocking Script"
   echo "Switch primary monitor"
   sudo -u $USER disper -s
   echo "Killall XCreateMouseVoid"
   pkill XCreate
   echo "Restart conky"
   pkill conky
   sudo -u $USER conky &
   

   chmod +x /usr/local/sbin/undock

7. Create the dock script (change your_user to match your user name):

   Script Name: /usr/local/sbin/dock

   #!/bin/bash
   USER=your_user
   export HOME=/home/$USER
   source $HOME/.Xdbus
   export DISPLAY=:0
   echo "Docking Script"
   echo "Switch to Dualview"
   sudo -u $USER disper -i < $HOME/.disperDocked
   echo "Start XCreateMouseVoid"
   pkill XCreate
   sudo -u $USER $HOME/.mousevoid
   echo "Restart conky"
   pkill conky
   sudo -u $USER conky &
   

   chmod +x /usr/local/sbin/dock

Debug

To debug the dock scripts you have to enable udev debug logging:

udevadm control --log-priority=debug

Then open syslog in Log File Viewer

Resources

nVidia Readme: Config Twinview, X Config Options
Autorandr
Disper PPA
nv-control-dpy
Ubuntu Forum - Un/Dock Scripts
Thinkwiki
udevadm