After X server update 1.18.4 `su — pi -c “startx” &` not working anymore
Jessie updated xserver-xorg-core to 1.18.4 from 1.17.2, to fix the problem
sudo dpkg-reconfigure x11-common
update-rc.d: warning: start and stop actions are no longer supported; falling back to defaults
sudo apt-get install xserver-xorg-legacy -y
sudo nano /etc/X11/Xwrapper.config
#Change console to anybody
allowed_users=anybody