Do executable files always open a terminal window on MacOS?

Question

I'm on MacOS X, and I'm pretty new to app-bundle-type things. I am writing a program that opens a window and registers mouse input -- not a command line tool. When I compile my code (written in C, if that is important) into an executable file (a "unix executable file") and then run that file directly (by double clicking it, for example), a terminal window pops up, and then the program's window pops up. Likewise, if I navigate to the directory of the executable and open it from the command line, it pops open /another/ terminal window and then the program's window.

However, if I wrap the executable in a bundle (thus, I suppose, turning it into a proper "app"), then when I run the app, either by double clicking or from the command line, the program's window opens and no new terminal window is created. Is this merely a property of the "app bundle"'s architecture? Or is there a way that I can run the raw executable without incurring another terminal window? I suspect that I'm misunderstanding something fundamental. Thanks in advance!

Answer 1

I believe what you're seeing is correct. In order for a separate window to not pop-up, you'd need to encapsulate it into a bundle.

Launching by double-clicking a bundle, or using the 'open' command from Terminal uses Apple's Launch Services , which maintains a list of known (registered) applications. When an application (bundle) is introduced to the system, it is registered with Launch Services and associated with its URI (eg com.apple.calculator), which is present in the bundle's Info.plist

Other items in the Info.plist tell launch services how to handle the application, such as checking if the minimum or maximum version of the OS has been exceeded, or whether or not to display a dock item.

A lone binary doesn't have an associated Info.plist manifest, so its behaviour can't be varied and a Terminal window is opened.

Answer 2

Bare executable files are essentially treated as documents by Launch Services (the framework that the Finder, Dock, and open command use when you open stuff). The application which handles such documents is Terminal. So, when you open an executable in that fashion, it launches Terminal if it's not already running and tells it to open the document. Terminal does this by opening a new shell window and auto-typing the path to the "document" as a command line.

Launch Services handles bundled apps as, well, apps. If the app is already running, it activates it and possibly has it open a new untitled window. Otherwise, it launches it.

As Rob Napier notes in the comments, if you run an executable directly from the command line (or if some already-running app launches it using NSTask or fork+exec), it will simply run. Launch Services won't be involved, so Terminal will not be asked to open the executable as a document.