Help request with "any change in directory"

Hi,
I have a simple need: monitor a directory for any changes underneath. As soon as *anything* changes OR *many things* have changed (file rename, addition, deletion, ...) I want to run some bash script (to sync the directory).
Note that I want the bash script to run once, not for each and every change that occurs, i.e. if three file names have changed, I want the script to be run once, *not* have it called three times(!)
Background info:
What I want to achive with this is to keep two directories in sync. For your information: I do use Chronosync, the Chronosync script runs once an hour (it does not support instant-sync, only scheduled sync). In between, when I am working in a directory, I want individual file changes to trigger the sync almost instantly after a change. Note that Hazel's sync is not good, it offers no bi-directional sync. So please, please don't start a discussion on syncing, but keep this topic to the question mentioned above "how to detect change(s) in a directory with hazel". The main problem is that I don't want Chronosync to run 50 times when 50 files change, just once will do the job.
I have a simple need: monitor a directory for any changes underneath. As soon as *anything* changes OR *many things* have changed (file rename, addition, deletion, ...) I want to run some bash script (to sync the directory).
Note that I want the bash script to run once, not for each and every change that occurs, i.e. if three file names have changed, I want the script to be run once, *not* have it called three times(!)
Background info:
What I want to achive with this is to keep two directories in sync. For your information: I do use Chronosync, the Chronosync script runs once an hour (it does not support instant-sync, only scheduled sync). In between, when I am working in a directory, I want individual file changes to trigger the sync almost instantly after a change. Note that Hazel's sync is not good, it offers no bi-directional sync. So please, please don't start a discussion on syncing, but keep this topic to the question mentioned above "how to detect change(s) in a directory with hazel". The main problem is that I don't want Chronosync to run 50 times when 50 files change, just once will do the job.