FileSystem

A file change watcher wrapper based on fs

System Support

• Mac fsevent
• Linux and FreeBSD inotify
• Windows inotify-win

NOTE: On Linux and FreeBSD you need to install inotify-tools.

Usage

Put file_system in the deps and application part of your mix.exs

defmodule Excellent.Mixfile do
  use Mix.Project

  def project do
  ...
  end

  defp deps do
    [
      { :file_system, "~> 0.1.0", only: :test },
    ]
  end
  ...
end

Subscription API

You can spawn a worker and subscribe to events from it:

{:ok, pid} = FileSystem.start_link(dirs: ["/path/to/some/files"])
FileSystem.subscribe(pid)

The pid you subscribed from will now receive messages like

{:file_event, worker_pid, {file_path, events}}

and

{:file_event, worker_pid, :stop}

Callback API

You can also use FileSystem to define a module with a callback that will be called when filesystem events occur. This requires you to specify directories to watch at compile-time.

write lib/monitor.ex

defmodule Monitor do
  use FileSystem, dirs: ["/tmp/test"]

  def callback(:stop) do
    IO.puts "STOP"
  end

  def callback(file_path, events) do
    IO.inspect {file_path, events}
  end
end

Execute in iex

iex > Monitor.start

Tweaking behaviour via listener extra arguments

For each platform, you can pass extra arguments to the underlying listener process via the listener_extra_args option.

Here is an example to get instant notifications on file changes for Mac OS X:

use FileSystem, dirs: ["/tmp/test"], listener_extra_args: "--latency=0.0"

See the fs source for more details.

List Events from Backend

iex > FileSystem.known_events