Its weird to see the time unit as below.
> repeat {
+ startTime <- now('Asia/Tokyo')
+ cat('Now is', as.character(now('Asia/Tokyo')), '(Asia/Tokyo).\n')
+ sleepTime <- startTime + 5*60 - now('Asia/Tokyo')
+ if (sleepTime > 0)
+ Sys.sleep(sleepTime)
+ }
Now is 2018-06-20 15:02:48 (Asia/Tokyo).
Now is 2018-06-20 15:02:53 (Asia/Tokyo).
Now is 2018-06-20 15:02:58 (Asia/Tokyo).
Now is 2018-06-20 15:03:03 (Asia/Tokyo).
> repeat {
+ startTime <- now('Asia/Tokyo')
+ cat('Now is', as.character(now('Asia/Tokyo')), '(Asia/Tokyo).\n')
+ sleepTime <- startTime + 120*60 - now('Asia/Tokyo')
+ if (sleepTime > 0)
+ Sys.sleep(sleepTime)
+ }
Now is 2018-06-20 15:03:21 (Asia/Tokyo).
Now is 2018-06-20 15:03:23 (Asia/Tokyo).
Now is 2018-06-20 15:03:25 (Asia/Tokyo).
Now is 2018-06-20 15:03:27 (Asia/Tokyo).
Now is 2018-06-20 15:03:29 (Asia/Tokyo).
Now is 2018-06-20 15:03:31 (Asia/Tokyo).
Now is 2018-06-20 15:03:33 (Asia/Tokyo).