File system notifications for Go

Build Status GoDoc

Cross platform, works on:

  • Windows
  • Linux
  • BSD
  • OSX
Moving Notice

We plan to include os/fsnotify in the Go standard library with a new API.

  • Import (GoDoc) for the latest API under development.
  • Continue importing (GoDoc) for the stable API.
  • Report Issues to go.exp/fsnotify after testing against
  • Join golang-dev to discuss fsnotify.
  • See the Contribution Guidelines for Go and sign the CLA.
package main

import (


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

	done := make(chan bool)

	// Process events
	go func() {
		for {
			select {
			case ev := <-watcher.Event:
				log.Println("event:", ev)
			case err := <-watcher.Error:
				log.Println("error:", err)

	err = watcher.Watch("testDir")
	if err != nil {


	/* ... do stuff ... */

For each event:

  • Name
  • IsCreate()
  • IsDelete()
  • IsModify()
  • IsRename()

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 in the works #56).

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 #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 #62). A temporary workaround is to add your folder(s) to the Spotlight Privacy settings until we have a native FSEvents implementation (see #54).

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.
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    Package fsnotify implements file system notification.




    View Source
    const (
    	FSN_CREATE = 1
    	FSN_MODIFY = 2
    	FSN_DELETE = 4
    	FSN_RENAME = 8


    This section is empty.


    This section is empty.


    type FileEvent

    type FileEvent struct {
    	Name string // File name (optional)
    	// contains filtered or unexported fields

    func (*FileEvent) IsAttrib

    func (e *FileEvent) IsAttrib() bool

      IsAttrib reports whether the FileEvent was triggered by a change in the file metadata.

      func (*FileEvent) IsCreate

      func (e *FileEvent) IsCreate() bool

        IsCreate reports whether the FileEvent was triggered by a creation

        func (*FileEvent) IsDelete

        func (e *FileEvent) IsDelete() bool

          IsDelete reports whether the FileEvent was triggered by a delete

          func (*FileEvent) IsModify

          func (e *FileEvent) IsModify() bool

            IsModify reports whether the FileEvent was triggered by a file modification or attribute change

            func (*FileEvent) IsRename

            func (e *FileEvent) IsRename() bool

              IsRename reports whether the FileEvent was triggered by a change name

              func (*FileEvent) String

              func (e *FileEvent) String() string

                String formats the event e in the form "filename: DELETE|MODIFY|..."

                type Watcher

                type Watcher struct {
                	Error chan error // Errors are sent on this channel
                	Event chan *FileEvent // Events are returned on this channel
                	// contains filtered or unexported fields

                func NewWatcher

                func NewWatcher() (*Watcher, error)

                  NewWatcher creates and returns a new inotify instance using inotify_init(2)


                  func (*Watcher) Close

                  func (w *Watcher) Close() error

                    Close closes an inotify watcher instance It sends a message to the reader goroutine to quit and removes all watches associated with the inotify instance

                    func (*Watcher) RemoveWatch

                    func (w *Watcher) RemoveWatch(path string) error

                      Remove a watch on a file

                      func (*Watcher) Watch

                      func (w *Watcher) Watch(path string) error

                        Watch a given file path

                        func (*Watcher) WatchFlags

                        func (w *Watcher) WatchFlags(path string, flags uint32) error

                          Watch a given file path for a particular set of notifications (FSN_MODIFY etc.)