def print_usage
puts "Usage: #{@app_name} <command> <options> -- <application options>"
puts
puts "* where <command> is one of:"
puts " start start an instance of the application"
puts " stop stop all instances of the application"
puts " restart stop all instances and restart them afterwards"
puts " reload send a SIGHUP to all instances of the application"
puts " run start the application and stay on top"
puts " zap set the application to a stopped state"
puts " status show status (PID) of application instances"
puts
puts "* and where <options> may contain several of the following:"
puts @optparse.usage
end