Question

We have an application that we have built as a bundle and we want to launch it from another process.

How should we do it?
From what I understand we can use openUrls(), openFile() or execve()
but I don’t know which one better suits us.

Thanks

Answer 1

Since you’re talking about an application, you don’t want to go through the file association mechanisms. They’re for opening documents, images etc. with an appropriate application. Since you don’t seem to be sure what to ask, I’d say keep it simple:

The exec* family launches an executable directly. But note that it replaces the launching process with the launched application. Your launcher will stop executing at that point. If you want the launcher to continue to run, you want to use something that launches a subprocess. The low-level way is fork/vfork followed by exec, but it’s far simpler to launch your app with system, which takes care of all that behind the scenes. (Assuming there are no security concerns about users on the other side of the world injecting execution paths).

If the launcher does not terminate as soon as it launches your app, you’ll want to think about whether it “blocks” until the launched application terminates, or whether it launches the app asynchronously– so that they then run in parallel. The launcher might also “wait” for the return value of the app, to check whether it succeeded and maybe do something afterwards. There are ways to do all that, but since we don’t know what you need, I won’t go into details.

In short: If the only job of your launcher is to start your app, use execl. If your launcher needs to do more, use system. If neither one quite fits your needs, you’ll need to provide more information– starting with the language your launcher is written in.

PS. Both of these have the advantage of generality and portability. They work for GUI and commandline applications, and they’ll work on any Unix-like system, and to some extent on Windows. There’s no need to lock yourself into Cocoa for something so simple.