execute_shell_command_from_cocoa_app.swift

    private func executeShellCommand(_ command: String) {
        let task = Process()
        let pipe = Pipe()

        task.standardOutput = pipe
        task.arguments = ["-c", command]
        task.launchPath = "/bin/bash"
//        task.launch()

        let outputHandle = pipe.fileHandleForReading
        outputHandle.waitForDataInBackgroundAndNotify()

        // When new data is available
        var dataAvailable : NSObjectProtocol!
        dataAvailable = NotificationCenter.default.addObserver(forName: NSNotification.Name.NSFileHandleDataAvailable, object: outputHandle, queue: nil) {  notification -> Void in
                let data = pipe.fileHandleForReading.availableData
                if data.count > 0 {
                    if let str = NSString(data: data, encoding: String.Encoding.utf8.rawValue) {
                        print("Task sent some data: \(str)")
                    }
                    outputHandle.waitForDataInBackgroundAndNotify()
                } else {
                    NotificationCenter.default.removeObserver(dataAvailable)
                }
        }

        // When task has finished
        var dataReady : NSObjectProtocol!
        dataReady = NotificationCenter.default.addObserver(forName: Process.didTerminateNotification, object: pipe.fileHandleForReading, queue: nil) { notification -> Void in
                print("Task terminated!")
                NotificationCenter.default.removeObserver(dataReady)
        }

        // Launch the task
        task.launch()
    }