Based on the main answer, given that I had to modify some of the instructions there:
The command to enable tap-to-click is therefore of the form:
xinput set-prop "device" "action" 1
To read the "device" you have to do
But it may prove difficult to identify the device in that list. Some tips: it is probably under "Virtual core pointer"; it may contain terms like "Syn", "Synaptics", "Touchpad", "Alps", "Glidepoint". e.g., mine was
AlpsPS/2 ALPS GlidePoint id=16, but I had to guess; as I was not sure I have tested if that was the correct ID number by disabling/enabling the touchpad with
xinput --disable 16 and
xinput --enable 16.
Now, to get rid of all the confusing names, ID-numbers can be used instead of the device and action names.
So, to read the "action":
xinput list-props 16
Which listed among others:
libinput Tapping Enabled (297): 0
So, using ID numbers instead of names, the final command was:
xinput set-prop 16 297 1
Note: for some reason, using the name of the action within the command, as suggested by the main answer, wouldn't work for me (
xinput set-prop ""AlpsPS/2 ALPS GlidePoint" "Tapping Enabled" 1), while using just the name of the device did work (
xinput set-prop "AlpsPS/2 ALPS GlidePoint" 297 1).
This command can be useful in systems where there is no GUI for such setting, like in the LXQT that I was testing at the date of the post.