how to launch a guest macos app from host macos?

when the guest OS is windows, you can launch an app inside the VM from the host os.
how do you do that when the guest is mac? command line is fine. is there ANY way to do this?

 

Good question. I can think of a couple of good reasons to be able to do this.

 

I discovered a method:
in the guest OS, mount a folder from the host OS
in that folder, attach a "Folder Action" that, when it sees a new file in the folder, launches an app or document (you can get creative here)
now, from the Host OS, drop a file into that folder
bingo: the Guest OS launches whatever you told it to in the folder action!