# File system notifications for Go
[](https://godoc.org/github.com/fsnotify/fsnotify) [](https://goreportcard.com/report/github.com/fsnotify/fsnotify)
fsnotify utilizes [golang.org/x/sys](https://godoc.org/golang.org/x/sys) rather than `syscall` from the standard library. Ensure you have the latest version installed by running:
```console
go get -u golang.org/x/sys/...
```
Cross platform: Windows, Linux, BSD and macOS.
| Adapter | OS | Status |
| --------------------- | -------------------------------- | ------------------------------------------------------------------------------------------------------------------------------- |
| inotify | Linux 2.6.27 or later, Android\* | Supported [](https://travis-ci.org/fsnotify/fsnotify) |
| kqueue | BSD, macOS, iOS\* | Supported [](https://travis-ci.org/fsnotify/fsnotify) |
| ReadDirectoryChangesW | Windows | Supported [](https://travis-ci.org/fsnotify/fsnotify) |
| FSEvents | macOS | [Planned](https://github.com/fsnotify/fsnotify/issues/11) |
| FEN | Solaris 11 | [In Progress](https://github.com/fsnotify/fsnotify/issues/12) |
| fanotify | Linux 2.6.37+ | [Planned](https://github.com/fsnotify/fsnotify/issues/114) |
| USN Journals | Windows | [Maybe](https://github.com/fsnotify/fsnotify/issues/53) |
| Polling | *All* | [Maybe](https://github.com/fsnotify/fsnotify/issues/9) |
\* Android and iOS are untested.
Please see [the documentation](https://godoc.org/github.com/fsnotify/fsnotify) and consult the [FAQ](#faq) for usage information.
## API stability
fsnotify is a fork of [howeyc/fsnotify](https://godoc.org/github.com/howeyc/fsnotify) with a new API as of v1.0. The API is based on [this design document](http://goo.gl/MrYxyA).
All [releases](https://github.com/fsnotify/fsnotify/releases) are tagged based on [Semantic Versioning](http://semver.org/). Further API changes are [planned](https://github.com/fsnotify/fsnotify/milestones), 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/github.com/fsnotify/fsnotify` within your project, and likewise for `golang.org/x/sys`.
## Usage
```go
package main
import (
"log"
"github.com/fsnotify/fsnotify"
)
func main() {
watcher, err := fsnotify.NewWatcher()
if err != nil {
log.Fatal(err)
}
defer watcher.Close()
done := make(chan bool)
go func() {
for {
select {
case event, ok := <-watcher.Events:
if !ok {
return
}
log.Println("event:", event)
if event.Op&fsnotify.Write == fsnotify.Write {
log.Println("modified file:", event.Name)
}
case err, ok := <-watcher.Errors:
if !ok {
return
}
log.Println("error:", err)
}
}
}()
err = watcher.Add("/tmp/foo")
if err != nil {
log.Fatal(err)
}
<-done
}
```
## Contributing
Please refer to [CONTRIBUTING][] before opening an issue or pull request.
## Example
See [example_test.go](https://github.com/fsnotify/fsnotify/blob/master/example_test.go).
## FAQ
**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][#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][#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.
[#62]: https://github.com/howeyc/fsnotify/issues/62
[#18]: https://github.com/fsnotify/fsnotify/issues/18
[#11]: https://github.com/fsnotify/fsnotify/issues/11
[#7]: https://github.com/howeyc/fsnotify/issues/7
[contributing]: https://github.com/fsnotify/fsnotify/blob/master/CONTRIBUTING.md
## Related Projects
* [notify](https://github.com/rjeczalik/notify)
* [fsevents](https://github.com/fsnotify/fsevents)