On Fri, Aug 30, 2019, 05:02 Hongyi Zhao <hongyi.zhao at gmail.com wrote: > On Fri, 30 Aug 2019 17:53:02 +1000, Chris Angelico wrote: > > (Also, why the sleep? Seems unnecessary.) > > Because without using sleep, the stuff on screen will display very > shortly and then disappear. Is this not your testing result? No it is not. What kind of terminal are you using?