Inotify

A Swift wrapper around the Linux inotify API, built on modern Swift concurrency. It lets you watch individual files or directories for filesystem events, recursively monitor entire subtrees, and optionally have newly created subdirectories watched automatically.

Events are delivered as an AsyncSequence, so you can consume them with a simple for await loop.

Adding Inotify to Your Project

Add the package dependency in your Package.swift:

dependencies: [
    .package(url: "https://github.com/astzweig/swift-inotify.git", from: "1.0.0")
]

Then add Inotify to your target's dependencies:

.target(
    ...
    dependencies: [
        .product(name: "Inotify", package: "swift-inotify")
    ]
    ...
)

Quick Start

import Inotify

let inotify = try Inotify()

// Watch a single file for modifications
try inotify.addWatch(path: "/tmp/some-existing-file.txt", mask: [.modify])

// Watch a single directory for file creations and modifications
try inotify.addWatch(path: "/tmp/watched", mask: [.create, .modify])

// Consume events as they arrive
for await event in await inotify.events {
    print("Event at \(event.path): \(event.mask)")
}

Watching Subtrees

Inotify operates on individual watch descriptors, so monitoring a directory does not automatically cover its children. This library provides two convenience methods that handle the recursion for you.

Recursive Watch

addRecursiveWatch walks the directory tree at setup time and installs a watch on every existing subdirectory:

try await inotify.addRecursiveWatch(
    forDirectory: "/home/user/project",
    mask: [.create, .modify, .delete]
)

Subdirectories created after the call are not watched.

Automatic Subtree Watching

addWatchWithAutomaticSubtreeWatching does everything addRecursiveWatch does, and additionally listens for CREATE events with the isDir flag. Whenever a new subdirectory appears, a watch is installed on it automatically:

try await inotify.addWatchWithAutomaticSubtreeWatching(
    forDirectory: "/home/user/project",
    mask: [.create, .modify, .delete]
)

This is the most convenient option when you need full coverage of a growing directory tree.

Excluding Items

You can tell the Inotify actor to ignore certain file or directory names. Excluded names are skipped during recursive directory resolution (so no watch is installed on them) and silently dropped from the event stream:

let inotify = try Inotify()

// Ignore version-control and build directories
await inotify.exclude(names: ".git", "node_modules", ".build")

try await inotify.addWatchWithAutomaticSubtreeWatching(
    forDirectory: "/home/user/project",
    mask: [.create, .modify, .delete]
)

Use isExcluded(_:) to check whether a name is currently on the exclusion list.

Event Masks

InotifyEventMask is an OptionSet that mirrors the native inotify flags. You can combine them freely.

Mask	Description
.access	File was read
.attrib	Metadata changed (permissions, timestamps, ...)
.closeWrite	File opened for writing was closed
.closeNoWrite	File not opened for writing was closed
.create	File or directory created in watched directory
.delete	File or directory deleted in watched directory
.deleteSelf	Watched item itself was deleted
.modify	File was written to
.moveSelf	Watched item itself was moved
.movedFrom	File moved out of watched directory
.movedTo	File moved into watched directory
.open	File was opened

Convenience combinations: .move (.movedFrom + .movedTo), .close (.closeWrite + .closeNoWrite), .allEvents.

Watch flags: .dontFollow, .onlyDir, .oneShot.

Kernel-only flags returned in events: .isDir, .ignored, .queueOverflow, .unmount.

Removing a Watch

Every addWatch variant returns one or more watch descriptors that you can use to remove the watch later:

let wd = try inotify.addWatch(path: "/tmp/watched", mask: .create)

// ... later
try inotify.removeWatch(wd)

Build Tool

The package ships with a task executable (the TaskCLI target) that serves as the project's build tool. It automates running tests and generating documentation inside Linux Docker containers, so you can validate everything on the correct platform even when developing on macOS. Because of a Swift Package Manager Bug in the package dependency resolution, the executable needs to be run using the task.sh shell script.

Tests

./task.sh test

Use -v, -vv, or -vvv to increase log verbosity. The command runs two passes: first all tests except InotifyLimitTests, then only InotifyLimitTests (which manipulate system-level inotify limits and need to run in isolation).

Docker must be installed and running on your machine.

Documentation

Full API documentation is available as DocC catalogs bundled with the package. Generate them locally with:

./task.sh generate-docs

Then open the files in the newly created public folder. Or preview in Xcode by selecting Product > Build Documentation.

Requirements

• Swift 6.0+
• Linux (inotify is a Linux-only API)
• Docker (for running the test suite via swift run task test)

License

See LICENSE for details.