Pre Sierra (or El Capitan? I dont remember..) you used to be able to edit the /Library/CoreServices/DefaultDesktop.jpg image, and it would set the background to whatever had that filename for all the users on the machine, that option now seems disabled with SIP 'operation not permitted' even when tried from terminal as root
So how can I have a Default Background set for every user that logs in to the machine, but with the option of changing it if they so choose?
Solved! Go to Solution.