mas provides a simple command-line interface for the Mac App Store. This interface is for automation and scripting.
This app works with the same system services that the Mac App Store. These two processes communicate through XPC as distinct processes. This causes mas to experience similar problems to the pasteboard when it runs inside tmux. To fix the pasteboard behavior, a wrapper tool is available that also works for mas.
More information about the installation process.
Version 1.8.3: