Set the output for the service command.

def set_output(self):
        """
        Set the output for the service command.
        """
        if not self.output:
            return open(devnull, 'w')
        
        # Get the output file path
        output_dir = dirname(self.output)
        
        # Make the path exists
        if not isdir(output_dir):
            try:
                makedirs(output_dir)
            except Exception as e:
                self.die('Failed to create output directory "{}": {}'.format(output_dir, str(e)))
        return open(self.output, 'a')