I've enabled tap-to-click in Gnome but it doesn't work on GDM.I tried running dconf-editor as root to modify the setting but to no avail.I also tried running sudo -u gdm gsettings set org.gnome.desktop.peripherals.touchpad tap-to-click true but I get the following error(process:16560): dconf-WARNING **: failed to commit changes to dconf: Error spawning command line 'dbus-launch --autolaunch=long-number-here --binary-syntax --close-stderr': Child process exited with code 1How do I enable tap-to-click on GDM?
GDM - how to enable touchpad tap-to-click
arch linux;gdm3
You have to export $(dbus-launch) and set the gsettings backend (tested  on archlinux with gdm 3.18.2):switch to a VT (e.g. Ctrl+Alt+F3), login as root and run:su - gdm -s /bin/shto switch user to gdm.then run:export $(dbus-launch)and:GSETTINGS_BACKEND=dconf gsettings set org.gnome.desktop.peripherals.touchpad tap-to-click truerun exit or hit Ctrl+D to return to root account.restart the display manager:systemctl restart gdmReverting is pretty much the same, just change true to false @ step 2.