I'd like to deactivate the touchpad permanently. (BTW: This should be included in the ubuntu-settings.)
2 Answers
Try downloading "pointing devices".
sudo apt-get install "gpointing-device-settings"
There is an option in there to disable the touchpad, and other cool things as well.
There is an option in System Settings > Mouse and Touchpad to turn touchpad off. However in 14.04 it's bugged & the touchpad gets turned back on when you restart or fresh boot. https://bugs.launchpad.net/ubuntu/+source/unity-settings-daemon/+bug/1283863
If you really wanted it gone then remove xserver-xorg-input-synaptics
package, however if you had an issue with your mouse you may regret that removal.
Here I've little use for the touchpad, (wireless mouse) so to workaround the bug I just use a autostart .desktop to disable on login. (placed in ~/.config/autostart as touchpad.desktop
Ex. below
[Desktop Entry]
Type=Application
Exec=gsettings set org.gnome.settings-daemon.peripherals.touchpad touchpad-enabled false
Hidden=false
NoDisplay=false
X-GNOME-Autostart-enabled=true
X-GNOME-Autostart-Delay=3
Name=no touchpad
Comment=disables touchpad