fsnotify

README

File system notifications for Go

GoDoc

Cross platform, works on:

• Windows
• Linux
• BSD
• OSX

Example:

package main

import (
	"log"

	"github.com/howeyc/fsnotify"
)

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

	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 {
		log.Fatal(err)
	}

	<-done

	/* ... do stuff ... */
	watcher.Close()
}

For each event:

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

Notes:

• When a file is renamed 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.
• 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.
• 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.

Documentation

Overview

Package fsnotify implements filesystem notification.

Index

• Constants
• func FD_ISSET(p *syscall.FdSet, i int) bool
• func FD_SET(p *syscall.FdSet, i int)
• func FD_ZERO(p *syscall.FdSet)
• type FileEvent
  • func (e *FileEvent) IsCreate() bool
  • func (e *FileEvent) IsDelete() bool
  • func (e *FileEvent) IsModify() bool
  • func (e *FileEvent) IsRename() bool
  • func (e *FileEvent) String() string
• type Watcher
  • func NewWatcher() (*Watcher, error)
  • func (w *Watcher) Close() error
  • func (w *Watcher) RemoveWatch(path string) error
  • func (w *Watcher) Watch(path string) error
  • func (w *Watcher) WatchFlags(path string, flags uint32) error

Examples

• NewWatcher

Constants

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

	FSN_ALL = FSN_MODIFY | FSN_DELETE | FSN_RENAME | FSN_CREATE
)

Functions

func FD_ISSET

func FD_ISSET(p *syscall.FdSet, i int) bool

func FD_SET

func FD_SET(p *syscall.FdSet, i int)

func FD_ZERO

func FD_ZERO(p *syscall.FdSet)

Types

type FileEvent

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

func (*FileEvent) IsCreate

func (e *FileEvent) IsCreate() bool

IsCreate reports whether the FileEvent was triggerd by a creation

func (*FileEvent) IsDelete

func (e *FileEvent) IsDelete() bool

IsDelete reports whether the FileEvent was triggerd by a delete

func (*FileEvent) IsModify

func (e *FileEvent) IsModify() bool

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

func (*FileEvent) IsRename

func (e *FileEvent) IsRename() bool

IsRename reports whether the FileEvent was triggerd 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)

Example

package main

import (
	"log"

	"github.com/howeyc/fsnotify"
)

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

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

	err = watcher.Watch("/tmp/foo")
	if err != nil {
		log.Fatal(err)
	}
}

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.)