How to track the appearance of a file in a directory?

Question

linux

The essence is this:
There is Cloud MailRu (free)
There is a server. It has a directory ( empty )

. subdirectory. But at the same time, it did not end, because if another file comes, do the same

Answer 1

1. look at the modification date of a directory
2. test "`echo dir/*`" != 'dir/*'
3. shopt -s nullglob ; files=*