Objective: Make the screen stay on forever for a raspberry pi
$ sudo cp /etc/lightdm/lightdm.conf /etc/lightdm/lightdm.conf.bkp
$ sudo vim /etc/lightdm/lightdm.conf
Then Add a line under this section:
[SeatDefaults]
xserver-command=X -s 0 -dpms
Source: https://www.raspberrypi.org/forums/viewtopic.php?t=138353#p918297