If I call shell commands in a GUI-wrapped Mac app, will it be rejected from the Mac App Store?
For example, I want to call osascript and change the audio output volume.
Thanks for any pointers.
Generally, they will not be rejected, if they meet the requirements of the Mac App Store Review Guidelines.
Reading this document there are no concerns with shell-script execution. Just look at point 2.26 to not run your code without asking the user for.
Remember that your app has to be sandboxed and should not interact with other applications, by directly calling or manipulating them. Shell scripts however play a different role. Your script has to be included in the applications bundle, to meet guideline requirements.
Do some great stuff with it!