File system notifications for Go

GoDoc Go Report Card

fsnotify utilizes rather than syscall from the standard library. Ensure you have the latest version installed by running:

go get -u

Cross platform: Windows, Linux, BSD and macOS.

Adapter OS Status
inotify Linux 2.6.27 or later, Android* Supported Build Status
kqueue BSD, macOS, iOS* Supported Build Status
ReadDirectoryChangesW Windows Supported Build Status
FSEvents macOS Planned
FEN Solaris 11 In Progress
fanotify Linux 2.6.37+ Planned
USN Journals Windows Maybe
Polling All Maybe

* Android and iOS are untested.

Please see the documentation and consult the FAQ for usage information.

API stability

fsnotify is a fork of howeyc/fsnotify with a new API as of v1.0. The API is based on this design document.

All releases are tagged based on Semantic Versioning. Further API changes are planned, and will be tagged with a new major revision number.

Go 1.6 supports dependencies located in the vendor/ folder. Unless you are creating a library, it is recommended that you copy fsnotify into vendor/ within your project, and likewise for


package main

import (


func main() {
	watcher, err := fsnotify.NewWatcher()
	if err != nil {
	defer watcher.Close()

	done := make(chan bool)
	go func() {
		for {
			select {
			case event, ok := <-watcher.Events:
				if !ok {
				log.Println("event:", event)
				if event.Op&fsnotify.Write == fsnotify.Write {
					log.Println("modified file:", event.Name)
			case err, ok := <-watcher.Errors:
				if !ok {
				log.Println("error:", err)

	err = watcher.Add("/tmp/foo")
	if err != nil {


Please refer to CONTRIBUTING before opening an issue or pull request.


See example_test.go.


When a file is moved to another directory is it still being watched?

No (it shouldn't be, unless you are watching where it was moved to).

When I watch a directory, are all subdirectories watched as well?

No, you must add watches for any directory you want to watch (a recursive watcher is on the roadmap #18).

Do I have to watch the Error and Event channels in a separate goroutine?

As of now, yes. Looking into making this single-thread friendly (see howeyc #7)

Why am I receiving multiple events for the same file on OS X?

Spotlight indexing on OS X can result in multiple events (see howeyc #62). A temporary workaround is to add your folder(s) to the Spotlight Privacy settings until we have a native FSEvents implementation (see #11).

How many files can be watched at once?

There are OS-specific limits as to how many watches can be created:

  • Linux: /proc/sys/fs/inotify/max_user_watches contains the limit, reaching this limit results in a "no space left on device" error.
  • BSD / OSX: sysctl variables "kern.maxfiles" and "kern.maxfilesperproc", reaching these limits results in a "too many open files" error.

Why don't notifications work with NFS filesystems or filesystem in userspace (FUSE)?

fsnotify requires support from underlying OS to work. The current NFS protocol does not provide network level support for file notifications.



    Package fsnotify provides a platform-independent interface for file system notifications.



    This section is empty.


    View Source
    var (
    	ErrEventOverflow = errors.New("fsnotify queue overflow")

      Common errors that can be reported by a watcher


      This section is empty.


      type Event

      type Event struct {
      	Name string // Relative path to the file or directory.
      	Op   Op     // File operation that triggered the event.

        Event represents a single file system notification.

        func (Event) String

        func (e Event) String() string

          String returns a string representation of the event in the form "file: REMOVE|WRITE|..."

          type Op

          type Op uint32

            Op describes a set of file operations.

            const (
            	Create Op = 1 << iota

              These are the generalized file operations that can trigger a notification.

              func (Op) String

              func (op Op) String() string

              type Watcher

              type Watcher struct {
              	Events chan Event
              	Errors chan error
              	// contains filtered or unexported fields

                Watcher watches a set of files, delivering events to a channel.

                func NewWatcher

                func NewWatcher() (*Watcher, error)

                  NewWatcher establishes a new watcher with the underlying OS and begins waiting for events.

                  func (*Watcher) Add

                  func (w *Watcher) Add(name string) error

                    Add starts watching the named file or directory (non-recursively).

                    func (*Watcher) Close

                    func (w *Watcher) Close() error

                      Close removes all watches and closes the events channel.

                      func (*Watcher) Remove

                      func (w *Watcher) Remove(name string) error

                        Remove stops watching the named file or directory (non-recursively).