| 1 | # fb-watchman
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| 2 |
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| 3 | `fb-watchman` is a filesystem watcher that uses the
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| 4 | [Watchman](https://facebook.github.io/watchman/) file watching service from
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| 5 | Facebook.
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| 6 |
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| 7 | Watchman provides file change notification services using very
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| 8 | efficient recursive watches and also allows more advanced change matching and
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| 9 | filesystem tree querying operations using
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| 10 | [a powerful expression syntax](https://facebook.github.io/watchman/docs/file-query.html#expressions).
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| 11 |
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| 12 | ## Install
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| 13 |
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| 14 | You should [install Watchman](
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| 15 | https://facebook.github.io/watchman/docs/install.html) to make the most of this
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| 16 | module.
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| 17 |
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| 18 | Then simply:
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| 19 |
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| 20 | ```
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| 21 | $ npm install fb-watchman
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| 22 | ```
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| 23 |
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| 24 | ## Key Concepts
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| 25 |
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| 26 | - Watchman recursively watches directories.
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| 27 | - Each watched directory is called a `root`.
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| 28 | - You must initiate a `watch` on a `root` using the `watch-project` command prior to subscribing to changes
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| 29 | - 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)
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| 30 | - change notifications are relative to the project root
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| 31 |
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| 32 | ## How do I use it?
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| 33 |
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| 34 | [Read the NodeJS watchman documentation](https://facebook.github.io/watchman/docs/nodejs.html)
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