So I want to check how many wal file got created in x minutes and how many .ready files got created in those x minutes.
It's not clear why you would want to track .ready files, they should be quite transient, and not a concern unless you are rolling your own archiving system (which you should not be). But Ron's suggestion of inotifywait is a good one for this. Probably listed as inotify or inotify-tools in your packaging system. Basic usage would be something like this, from the data directory:
