# fb-watchman`fb-watchman` is a filesystem watcher that uses the[Watchman](https://facebook.github.io/watchman/) file watching service fromFacebook.Watchman provides file change notification services using veryefficient recursive watches and also allows more advanced change matching andfilesystem tree querying operations using[a powerful expression syntax](https://facebook.github.io/watchman/docs/file-query.html#expressions).## InstallYou should [install Watchman](https://facebook.github.io/watchman/docs/install.html) to make the most of thismodule.Then simply:```$ npm install fb-watchman```## Key Concepts- Watchman recursively watches directories.- Each watched directory is called a `root`.- You must initiate a `watch` on a `root` using the `watch-project` command prior to subscribing to changes- Rather than separately watching many sibling directories, `watch-project` consolidates and re-uses existing watches relative to a project root (the location of your `.watchmanconfig` or source control repository root)- change notifications are relative to the project root## How do I use it?[Read the NodeJS watchman documentation](https://facebook.github.io/watchman/docs/nodejs.html)