Automating OS installations is going to eventually be about as easy on macOS as it is in iOS (er, if you have MDM that is). But in the meantime, it’s getting a bit more challenging. The obvious way Apple would prefer this to happen these days is via the startosinstall command that first shipped with El Capitan and with brtool getting moved around all the time, and becoming less of a thing, there’s one quick and easy thing you can do:
sudo "/Applications/Install macOS Sierra.app/Contents/Resources/startosinstall" --applicationpath "/Applications/Install macOS Sierra.app" --agreetolicense --nointeraction --volume /Volumes/Macintosh\ HD
In the above command, we’ve dropped “Install macOS Sierra.app” on a machine. While you’d guess that it would find the application path based on its own surname, we went ahead and supplied it as that seems to basically be a thing. Basically, –agreetolicense keeps us from having to run some expect scripts to accept a license agreement, –nointeraction suppresses as many of the screens as possible, and –volume allows us to install to any volume we’d like. This isn’t fully automated, but I have been able to layer in some more logic to quit apps before the script fires and then expect out other items from the script to automate a restart, watching for osinstallersetupd as a key.
This is all a bit bulkier than just using something like createOSXinstallPkg but it’s important to mention that there are a number of system components that are allowed for in SIP that use osinstallersetupd and so this blessed mechanism is likely the future until you can trigger an OS upgrade (and update I suppose) using an MDM command.
