Running shell scripts on iPad/iPhone

What would be the reason to run shell scripts?

Objective-C can print "Hello World" just fine.

Don't do it.

Use the approved APIs.

You'll risk almost certain rejection if you don't.

You can do this, but you have to jump through some hoops. The App Store guidelines explicity say that apps that install or launch other executable code will be rejected. Your app can include an embedded interpreter that executes scripts included as resources in your app. You cannot download new scripts because that is explicitly forbidden too. But if you include the scripts in the app, and include an embedded interpreter in the app, you should be fine.

That's a fairly advanced topic. I don't know if you will find many tutorials. I've heard that Lua is relatively easy to embed and use and other people have used it for iOS. See http://www.luanova.org/ioswithlua