Activate tap to click on touchpad?

Debian Jessie

To enable the touchpad tapping permanently , copy the 50-synaptics.conf file to /etc/X11/xorg.conf.d then edit it by adding Option "TapButton1" "1" .

As root:

mkdir /etc/X11/xorg.conf.d
cp /usr/share/X11/xorg.conf.d/50-synaptics.conf /etc/X11/xorg.conf.d/50-synaptics.conf

The /etc/X11/xorg.conf.d/50-synaptics.conf should be:

Section "InputClass"
        Identifier "touchpad catchall"
        Driver "synaptics"
        MatchIsTouchpad "on"
        Option "TapButton1" "1"
        Option "TapButton2" "3"

Reboot your system

Debian Stretch and Buster (updated)

Remove the xserver-xorg-input-synaptics package. (important)

# apt remove xserver-xorg-input-synaptics

Install xserver-xorg-input-libinput:

# apt install xserver-xorg-input-libinput

In most cases, make sure you have the xserver-xorg-input-libinput package installed, and not the xserver-xorg-input-synaptics package.

As root:

create /etc/X11/xorg.conf.d/

mkdir /etc/X11/xorg.conf.d

Create the 40-libinput.conf file:

echo 'Section "InputClass"
        Identifier "libinput touchpad catchall"
        MatchIsTouchpad "on"
        MatchDevicePath "/dev/input/event*"
        Driver "libinput"
        Option "Tapping" "on"
EndSection' > /etc/X11/xorg.conf.d/40-libinput.conf

restart your DM; e,g:

# systemctl restart lightdm

or

# systemctl restart gdm3

Debian wiki : Enable tapping on touchpad

In recent systems (2017) as many distros are moving to Wayland, synaptics driver is no longer used. Instead, libinput is used.

To enable tap to click on touchpad using libinput create a file in Xorg config:

$ touch /etc/X11/xorg.conf.d/99-synaptics-overrides.conf

And add the following configuration:

Section  "InputClass"
    Identifier  "touchpad overrides"
    Driver "libinput"
    MatchIsTouchpad "on"
    Option "Tapping" "on"
    Option "TappingButtonMap" "lmr"
EndSection

This does the trick for me in similar situation under Debian 8.6 and LXDE:

synclient TapButton1=1

Above works if synaptics touchpad work with Synaptics Driver xserver-xorg-input-synaptics.

If you are working with libinput driver (default driver in many live images):

xinput set-prop 'SynPS/2 Synaptics TouchPad' 'libinput Tapping Enabled' 1

You can use xinput list-props 'SynPS/2 Synaptics TouchPad' to see all available properties that can be adjusted for your TouchPad.

If your system uses libinput you can use xinput to find out the name of your touchpad device if the above command doesn't work (they aren't all Synaptics). For example:

Output for xinput:

⎡ Virtual core pointer                          id=2    [master pointer  (3)]
⎜   ↳ Virtual core XTEST pointer                id=4    [slave  pointer  (2)]
⎜   ↳ AlpsPS/2 ALPS GlidePoint                  id=11   [slave  pointer  (2)]
⎣ Virtual core keyboard                         id=3    [master keyboard (2)]
↳ Virtual core XTEST keyboard               id=5    [slave  keyboard (3)]
↳ Video Bus                                 id=6    [slave  keyboard (3)]
↳ Power Button                              id=7    [slave  keyboard (3)]
↳ Sleep Button                              id=8    [slave  keyboard (3)]
↳ Dell WMI hotkeys                          id=9    [slave  keyboard (3)]
↳ AT Translated Set 2 keyboard              id=10   [slave  keyboard (3)]

Command to enable clicking:

xinput set-prop 'AlpsPS/2 ALPS GlidePoint' 'libinput Tapping Enabled' 1