/cc @johnbender @mitchellh (suggests from vagrant perspective?)
This is due to the way that the VirtualBox shared folder system is implemented. It doesn't properly trigger filesystem notification events on the guest if it is touched from the host (and vice versa as well).
I don't think this is a bug with this project or Vagrant. However, listen may be able to watch file system properties (file mtime and such) and see the differences.
Listen has a polling adapter which does not depend on filesystem notifications. Could you try it and see if it helps? (To use it you have to enable the :force_polling option. See the readme for more info)
I just come back from vacation, this is still an issue?
I'm also having this same issue. Polling works fine for me (Lion as the host, Ubuntu 12.04 as vagrant) but I'd rather not eat up my processor time unnecessarily.
To understand this better: is this a problem outside of listen, or is it something which can be fixed in listen? I note elsewhere that Watchr appears to work in this scenario (I've yet to try it myself) and judging by their implementation they keep track of the a/m/ctime: https://github.com/mynyml/watchr/blob/master/lib/watchr/event_handlers/unix.rb
@ideasasylum Watchr use a different (evented) approach than Listen (that have some caveat, like not detecting new files). So if VirtualBox shared folder doesn't trigger filesystem notification events I think polling is the only option here. Sorry.
@thibaudgg ah, thanks for the explanation. If it was something that could be fixed I'd have had a go myself but polling seems like the best approach for the moment