Ubuntu supports input-hotplug. With this functionality, it's likely that you won't need to do any configuration at all to make your devices work, assuming they're recognized and set up by the kernel. However, if you do need to do adjust things, read on.

Dynamic Input Configuration with xinput

The xinput command line tool can be used for some on-the-fly configuration adjustments.

To view a listing of the input devices X sees, run:

$ xinput list
⎡ Virtual core pointer                          id=2    [master pointer  (3)]
⎜   ↳ Virtual core XTEST pointer                id=4    [slave  pointer  (2)]
⎜   ↳ SynPS/2 Synaptics TouchPad                id=8    [slave  pointer  (2)]
⎜   ↳ Logitech USB Receiver                     id=9    [slave  pointer  (2)]
⎣ Virtual core keyboard                         id=3    [master keyboard (2)]
    ↳ Virtual core XTEST keyboard               id=5    [slave  keyboard (3)]
    ↳ Power Button                              id=6    [slave  keyboard (3)]
    ↳ Lite-On Technology Corp. ThinkPad USB Keyboard with TrackPoint    id=7    [slave  keyboard (3)]

Individual devices can be queried for more details by using the numerical id or the name:

$ xinput query-state 9
2 classes :
ValuatorClass Mode=Relative Proximity=In

xinput can also be used to alter the button mappings on mice and adjust the acceleration and feedback settings.

Different input drivers may also expose arbitrary properties for applications to set. Synaptics touchpads are particularly configurable like this, but other devices have some more general properties.

$ xinput list-props 8
Device 'SynPS/2 Synaptics TouchPad':
        Device Enabled:         1
        Synaptics Edges:                1632, 5312, 1575, 4281
        Synaptics Finger:               25, 30, 256
        Synaptics Tap Time:             180
        Synaptics Tap Move:             220
        Synaptics Tap Durations:                180, 180, 100
        Synaptics Tap FastTap:          0

$ xinput set-int-prop 8 "Device Enabled" 8 0
$ xinput list-props 8
Device 'SynPS/2 Synaptics TouchPad':
        Device Enabled:         0
        Synaptics Edges:                1632, 5312, 1575, 4281
        Synaptics Finger:               25, 30, 256
        Synaptics Tap Time:             180
        Synaptics Tap Move:             220
        Synaptics Tap Durations:                180, 180, 100
        Synaptics Tap FastTap:          0

Input Configuration with InputClass sections

To set e.g. the Coordinate Transformation Matrix in an xorg.conf type file (e.g., /etc/X11/xorg.conf.d/90-rotate-screen.conf), set the "TransformationMatrix" option (NOT "CoordinateTransformationMatrix" or "Coordinate Transformation Matrix"!!!!) in an InputDevice or InputClass section; for example:

Section "InputClass"
    Identifier    "RotateTouchCW"
    MatchProduct    "N-Trig MultiTouch"
    Option    "TransformationMatrix" "0 1 0 -1 0 1 0 0 1"

Example: Disabling middle-mouse button paste on a scrollwheel mouse

Scrollwheel mice support a middle-button click event when pressing the scrollwheel. This is a great feature, but you may find it irritating. Fortunately it can be disabled.

First, you need to know the id of the mouse, like this:

$ xinput list | grep 'id='

"Virtual core pointer"  id=0    [XPointer]
"Virtual core keyboard" id=1    [XKeyboard]
"AT Translated Set 2 keyboard"  id=2    [XExtensionKeyboard]
"Macintosh mouse button emulation"      id=3    [XExtensionPointer]
"Logitech USB-PS/2 Optical Mouse"       id=4    [XExtensionPointer]

My mouse has the Logitech logo printed on it, so I gather I need the last entry.

I can view the current button mapping thusly:

$ xinput get-button-map 4

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 10

Really, only the first three numbers have meaning for me. They represent the left, middle, and right mouse buttons.

$ xinput get-button-map 4

I can turn the middle mouse button off by setting it to 0:

$ xinput set-button-map 4 1 0 3

Or I can turn the middle-mouse button into a left-mouse button by setting it to 1:

$ xinput set-button-map 4 1 1 3

To make this set on a per-user basis, I can plug that line into my ~/.xstartup or other init file. It can also be done via configuring a matching InputClass section on xorg.conf.

Contributed Documentation

The following documentation was provided by various people in the past. Generally, much of it was written for pre-InputHotplug X, so may or may not still work in Intrepid.

Keyboard Config

Mouse Config

Tablet Config

Touchpad Config

Game Controller Config

Don't Zap


  • Get to the System->Preferences->Keyboard menu.

  • Select the "Layouts" tab and click on the "Options" button.
  • Then select "Key sequence to kill the X server" and enable "Control + Alt + Backspace".

If this doesn't work (e.g. the option is unchecked but the key sequence still works), you can edit your /etc/X11/xorg.conf as explained below

Using KDE

  • Open System Settings and go to Input Devices.

  • In the Keyboard section open the Advanced tab.

  • Check the Configure keyboard options box if it's not already enabled.

  • Expand the Key sequence to kill the X server option and check the box labelled Control + Alt + Backspace.

  • Make sure to click the Apply button to apply the changes.

Using the command line

You can type the following command to enable Zapping immediately.

      setxkbmap -option terminate:ctrl_alt_bksp

If you're happy with the new behaviour you can add that command to your ~/.xinitrc in order to make the change permanent.

Sticky Keys

It may be worth mentioning that the Accessibility shortcuts (for both KDE and Gnome) are enabled by holding the shift-key for 8 seconds. (This is easy to do if, say, selecting multiple items with the mouse). As a result, it's easy to inadvertently enable "Sticky Keys". Now, if you press Ctrl and then release it, and a bit later, you press Alt-Bksp (the shortcut to delete a whole word), then Boom! Bye-bye X-session Sad Sad :-(

Also, unlike Ctrl-Alt-Del, the Ctrl-Alt-Bksp shortcut is not trapped. It's instant death (without confirmation) for the X-server, and too bad about your unsaved files. That's why DontZap is a good default.

For anyone missing the ability to kill the X-server in emergency, may I point out Alt-SysRq-R, followed by Ctrl-Alt-F1 (the first puts the keyboard back into Raw mode, i.e. outside the control of the X-server; the latter switches Virtual Terminal.) Or you can use Alt-SysRq-K to kill the current session.

X/Config/Input (last edited 2012-12-21 12:38:00 by 027edfa5)