I can sync folders with `rsync -avz /directory /target`, now I wish to do it if I changed a file in `/directory` so `rsync` should be called automatically.

I am using Virtual Box and the shared folder of Virtual Box is really slow, especially if you have a webpage which is using the shared folder as document root. With `rsync` i would be able to work with my local files on shared folder and sync it automatically with document root.

I hope someone has an idea how to do so,`crontab` would be not good, because it is executed each x minutes, so if i don't do anything, it will still call `rsync` but not if I modified my file.

Best regards