Latitude X300 & trackpad

16 Mar 2005

As I’ve mentioned before, I am running Linux on my Dell Latitude X300.

Like most laptops these days, it has a trackpad. While annoying, trackpads are far less annoying than the alternative – those little button knobs in the middle of the keyboard.

One annoyance though is accidentally clicking the trackpad (which takes as little as a light brush with your thumb), which while typing can have all sorts of unfortunate side-effects .. minimizing the window, closing it, losing focus, etc.

Fortunately, using a combination of hacks, I have tamed the touchpad. (Yes, I am using “touchpad” and “trackpad” alternately. At first, I did it by accident, but now I am doing it on purpose since people will probably search for both, and I want to be Google Friendly!) Specifically, what I was interested in was:

Disabling the trackpad entirely while I have a USB mouse plugged in.
Disabling the trackpad temporarily while typing.
Having a transition between the two states be quick and convenient.

Here’s How I Did It:

First, you’ll need to get and install the Synaptics touchpad driver for XFree86/Xorg (outside the scope of this document).
The driver comes with two utilities:
- synclient – this program allows you to change various settings for the touchpad, including disabling it entirely.
- syndaemon – this handy program runs as a daemon and will detect typing and disable the touchpad until the keyboard is idle for a customizable amount of time.
Customize the following script to your needs. Several things may differ for your specific environment: <pre>#!/bin/bash PATH=$PATH:/usr/sbin:/sbin PIDDIR=/home/cwage/var/run/ SYNDAEMON=/usr/local/bin/syndaemon SYNCLIENT=/usr/local/bin/synclient

while true do

There is probably a better way to look for a running Xserver, but this will

do for now. This exits the script immediately if the X server dies. Prevents

80 million copies of the script hanging around if you restart X.

if [ ! -S /tmp/.X11-unix/X0 ]; then exit fi

This next test is how I test for the presence of a USB mouse on my

system. You could also do “grep -i Mouse /proc/bus/usb/devices” but I

had a bizarre problem with my laptop wherein the mouse actually

disappeared from /proc/bus/usb/devices while I moved the mouse (?!)

Sometimes it’s easier to just pretend some things never happened and

move on.

        if [ -d /sys/class/input/mouse1 ]; then if $SYNCLIENT -l | grep 'TouchpadOff          = 0' > /dev/null; # If we've detected a mouse and the touchpad is on, turn it off # and start syndaemon then start-stop-daemon --stop --pid  \ $PIDDIR/syndaemon.pid --exec $SYNDAEMON
            $SYNCLIENT TouchpadOff=1 fi
        else if $SYNCLIENT -l | grep 'TouchpadOff          = 1' > /dev/null; then if ! ps auxw | grep syndaemon | grep -v grep > /dev/null; then
            $SYNCLIENT TouchpadOff=0 start-stop-daemon --background -m --start --pid \ $PIDDIR/syndaemon.pid --exec $SYNDAEMON -- -i 0.2 fi else start-stop-daemon --background -m --start --pid \ $PIDDIR/syndaemon.pid --exec $SYNDAEMON -- -i 0.2 fi
        fi
sleep 3 done

</pre>

Put this script in your .xsession or something that gets executed when you first log into X. It will run and constantly monitor for a USB mouse, or a lack thereof, and do the right thing. Voila!

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