How do you update Server.app from Terminal?

Good question. But alas, no. Remember Apple is a consumer company. App Store is consumer friendly, enterprise averse.

Depending on your licensing model, the best way to handle this is to have a master machine that has access to all your enterprise purchased app store apps. When there is an update, use this master machine to get the updates. Once you have them, use ARD, JAMF, or other tools to push these new Apps out to the fleet.

This method works well for simple bundle based apps with no additional payload. If you are supporting developers and need to push Xcode, recall that there are first run scripts and additional updates such as device simulation and command line tools that must be run post.

Hope this helps. Good luck.

Unfortunately an increasing number of Apple products get their updates from the App Store and even if the original item was free e.g. Xcode, you need to enter the App Store username and password to authorise getting the update.

The update is then directly installed on to the computer and is not in a form you can distribute via ARD.

(As it happens if you have a Developer account you can get Xcode via that.)

This is really Enterprise unfriendly 😟