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Extreme Multihead

Configuring Multiple Monitors

  • Experiment to find best setup (xrandr)
  • Make the setup default (xorg.conf.d)

Accessing Remote Systems from a Single Desktops

  • Simple remote access (rdc)
  • Complex remote access (Xdmc)
  • Keyboard & Mouse Sharing (Synergy)
  • Complete Integration (Xdmx)

Several monitors can be attached to a single computer system. Many years ago this was only possible by installing two or more video cards in a computer. Then some high-end video cards began appearing with outputs for two monitors. Nowadays, most laptops come with a main display and a socket for an external monitor while the integrated video cards on desktop systems provide VGA + DVI + HDMI outputs as standard. If you plug in multiple monitors to whatever video sockets you have available, they will more often than not "just work" - offering two or more versions of the same display. In some cases this is exactly what is required; allowing the same desktop to be viewed from different directions.

It is also possible to have these multiple monitors work together as an extended single desktop. It is even possible to join the displays from several computers - each with single or multiple monitors - into one very large extended desktop.

This document describes how to go configure such a system.

Experimenting with Multiple Monitors

The easiest way to begin experimenting with multiple monitors is start with a system which has a working X setup supporting a single monitor. If you already have the additional equipment installed

  • a video card with multiple video outputs or multiple vide cards
  • monitors plugged into each of the video outputs

When everything is on you should see the same output on each monitor. The desktop is "cloned" on to the secondary monitors. If all the monitors are not exactly the same shape or support different resolutions you may only see portions of the main desktop display.

The best tool to experiment with configuring your monitors to display as you want is xrandr. This may already installed as part of your Xorg installation from either the xorg or xorg-apps packages.

Use xrandr to experiment with different configurations until you arrive at settings you want to make permanent. The dualhead and xrandr pages, the man page and various locations on the web provide more information on using the tool.

For example, the following command configures my dual monitor setup:

{{|xrandr --output VGA-0 --rotate left --output VGA-0 --pos 0x0 --output DVI-0 --rotate left  --output DVI-0 --pos 1080x0}}

If you have not done so already, create a simple batch script containing your desired xrandr command. Save it somewhere useful; /usr/local/bin perhaps. Your system can then be configured to call this script as you login to your account as your window manager starts. There are different locations for saving initialisation commands and indeed some Settings tools can add these commands in place for you.






If none of the above options are available to you or you need a generic solution that will apply across all window managers and/or users; add the command to either to individual or system xinitrc scripts: - system-wide initialisation file is /etc/X11/xinit/xinitrc; add a line after the window manager has been started but before any applications are called