Touchpad Control

[Forester]

There are two drawbacks to using a laptop: the touchpad and the touchpad.

First, you are typing something and the touchpad decides you've tapped in the secret code for "destroy, destroy, frustration is irrelevant" and whatever it was you were doing is gone.

Second, this still happens even though you've plugged in an external mouse and aren't using the touchpad at all.

The route to solving the first problem is through syndaemon and the route to solving the second is through synclient. Both are command line apps already installed in Knoppix (6.4.4. at least).

To get the right settings automatically when Knoppix start-ups you need an additional script in /etc/X11/Xsession.d and to get the settings to change automagically when you plug-in or unplug a USB mouse, you need to add an extra pair of rules to /etc/udev/rules.d.

There are examples of how to do this out there but they usually start with someone complaining what used to work has stopped and could they crib a new solution from someone who has already done all the hard work.

Seems Knoppix is no exception and none of the solutions out there work. Seems xhost + is missing somewhere for sentimental reasons or perhaps Knoppix is just using a very new X server with new and improved security (the kind that got Windows Vista such a bad name).

Here's my take on this:

# /etc/udev/rules.d/75-touchpad.rules
# Disable touchpad when USB mouse is plugged in and reenable when USB mouse is removed

ACTION=="add",    SUBSYSTEM=="input", ENV{ID_INPUT_MOUSE}=="1", RUN+="/etc/X11/Xsession.d/50touchpad 1"
ACTION=="remove", SUBSYSTEM=="input", ENV{ID_INPUT_MOUSE}=="1", RUN+="/etc/X11/Xsession.d/50touchpad 0"

# EOF

and

#!/bin/sh
# /etc/X11/Xsession.d/50touchpad

if pidof X >/dev/null; then

  # Turn touchpad off when a USB mouse is present

  pidfile=/var/run/syndaemon.pid;

  if [ -n "${XAUTHORITY}" ]; then
    # Xsession initialisation

    if lsusb -v 2>/dev/null | grep -qF Mouse; then
      synclient TouchpadOff=1;
    else
      syndaemon -d -t -k -p $pidfile;
    fi
  else
    # udev hotplug event

    DISPLAY=":0";
    USER=$(who | awk "/ $DISPLAY /"'{print $1}');
    XAUTHORITY=/home/$USER/.Xauthority;
    export DISPLAY XAUTHORITY;

    synclient TouchpadOff=$1;

    if [ "$1" -eq 1 ]; then
      [ -f $pidfile ] && kill $(cat $pidfile);
      [ -f $pidfile ] && sync;
    else
      [ ! -f $pidfile ] && syndaemon -d -t -k -p $pidfile;
      [ ! -f $pidfile ] && sync;
    fi
  fi

fi

# EOF

The second must be executable as it is called by the rules in the first.

Enjoy.