Flier

Linux file-system helpers for Elixir, implemented as Rust NIFs:

• Flier.Inotify — watch a directory for events (create, modify, delete, move, open, close, access, attribute changes) via inotify, as messages or as a Stream.
• Flier.Entries — lazily stream the entries of a directory, flat or recursively, with their file type.

Flier is Linux-only. Precompiled NIFs are provided for x86_64, aarch64, 32-bit ARM (gnueabihf) and riscv64 glibc targets, so no Rust toolchain is needed.

Installation

def deps do
  [
    {:flier, "~> 0.6.0"}
  ]
end

To build the NIFs from source instead (for example on musl), see "Building from source" in the Flier module docs.

Watching a directory

Messages are tagged with the watcher's ref, so several watchers can share a process:

{:ok, %Flier.Inotify.Watcher{ref: ref} = watcher} =
  Flier.Inotify.start_watcher("/tmp", [:create, :delete])

receive do
  {:inotify_event, ^ref, %Flier.Inotify.Event{name: name, masks: masks}} ->
    IO.puts("#{name}: #{inspect(masks)}")
end

:stopped = Flier.Inotify.stop_watcher(watcher)

Or as a stream, which starts and stops the watcher for you:

"/tmp"
|> Flier.Inotify.stream([:close_write])
|> Enum.each(fn event -> IO.puts("#{event.name}: #{inspect(event.masks)}") end)

The :moved_from and :moved_to events of a rename carry the same :cookie, so the two halves can be paired up.

Errors are POSIX error atoms, as with File:

{:error, :enoent} = Flier.Inotify.start_watcher("/does/not/exist", :all)

Listing a directory

"/tmp"
|> Flier.Entries.stream()
|> Enum.each(fn entry -> IO.puts("#{entry.name} is a #{entry.type}") end)

Recursively, with an optional depth limit and symlink following:

root = "/home/user/projects"

root
|> Flier.Entries.stream(recursive: true, max_depth: 3)
|> Stream.filter(&(&1.type == :file))
|> Enum.map(&Path.join([root, &1.path, &1.name]))

If the root directory cannot be read, enumerating the stream raises a File.Error. Unreadable subdirectories are skipped, unless on_error: :raise is given.

Documentation

Full documentation is at https://hexdocs.pm/flier.