iMac defaulting to extend display rather than Duplicate

[abcedillo]

I have looked through the policies that are able to be created in JAMF and can't find anything related to what I am trying to do.

We have iMacs in classrooms connected to a projector and the iMac is defaulting to extend and would like for the default to be duplicate. Any suggestions? 

[AJPinto]

For you to be able to do this Apple would need to have a binary (for a script) or Preference Domain (for a Configuration Profile) that could be used to set or manage this, and I don't think that exists. 

You will not be able to do this without some kind of 3rd party tool. You can look into tools like displayplacer and see if that helps.

[wakco]

There is no configuration method for this, the only option is to log into the iMac in question as an administrator, configure it correctly, and then the iMac will default correctly (depending on macOS version, this may or may not include the login window).

The basic problem is these settings are usually "ByHost" settings within each users profile, which mean if the iMac is move to another Projector, or the user profile is moved to another Mac, the settings won't follow, even though the file containing the settings will, due to the file being designed to be unique to a specific hardware configuration.

But just so you are aware, the file you are looking for is 

~/Library/Preferences/ByHost/com.apple.windowserver.displays.12345678-1234-1234-1234-123456789ABC.plist where those numbers & letters between displays and plist is the UID used to identify the hardware configuration.

[abcedillo]

Thank you, for this it gives me somewhere to start and do some testing. The Macs in question are running macOS 15.2.0. I went in with the administrator log in and changed the settings then logged in with my regular log in and the settings reverted back to expand. 

Again thank you! I will do some testing!

[wakco]

Thank you, ours aren't on 15 yet, and normally wouldn't be for another year, however due to some new ones, this year they will be so good to know there might be an issue. I'll keep an eye on this as well.

[wakco · Accepted solution]

Also now that I think about it, while not fully automatic, a cheat might be to do the config manually as an admin, then copy the file (and basic folder structure) into all of the language profiles (.lproj folders) in /Library/User Template/, i.e. from /Users/adminusername/Library/Preferences/ByHost/com.apple.windowserver.displays.12345678-1234-1234-1234-123456789ABC.plist to /Library/User\ Template/English.lproj/Library/Preferences/ByHost/com.apple.windowserver.displays.12345678-1234-1234-1234-123456789ABC.plist making sure to preserve the UID. That may solve the problem, I'll try it myself once I have upgraded ours.

[abcedillo]

I will be working on this and testing this out as well! Will let you know how it goes!