131 lines
5.5 KiB
Markdown
131 lines
5.5 KiB
Markdown
# File system notifications for Go
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[](https://godoc.org/github.com/fsnotify/fsnotify) [](https://goreportcard.com/report/github.com/fsnotify/fsnotify)
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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:
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```console
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go get -u golang.org/x/sys/...
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```
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Cross platform: Windows, Linux, BSD and macOS.
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| Adapter | OS | Status |
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| --------------------- | -------------------------------- | ------------------------------------------------------------------------------------------------------------------------------- |
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| inotify | Linux 2.6.27 or later, Android\* | Supported |
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| kqueue | BSD, macOS, iOS\* | Supported |
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| ReadDirectoryChangesW | Windows | Supported |
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| FSEvents | macOS | [Planned](https://github.com/fsnotify/fsnotify/issues/11) |
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| FEN | Solaris 11 | [In Progress](https://github.com/fsnotify/fsnotify/issues/12) |
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| fanotify | Linux 2.6.37+ | [Planned](https://github.com/fsnotify/fsnotify/issues/114) |
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| USN Journals | Windows | [Maybe](https://github.com/fsnotify/fsnotify/issues/53) |
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| Polling | *All* | [Maybe](https://github.com/fsnotify/fsnotify/issues/9) |
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\* Android and iOS are untested.
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Please see [the documentation](https://godoc.org/github.com/fsnotify/fsnotify) and consult the [FAQ](#faq) for usage information.
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## API stability
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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).
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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.
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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`.
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## Usage
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```go
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package main
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import (
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"log"
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"github.com/fsnotify/fsnotify"
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)
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func main() {
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watcher, err := fsnotify.NewWatcher()
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if err != nil {
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log.Fatal(err)
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}
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defer watcher.Close()
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done := make(chan bool)
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go func() {
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for {
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select {
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case event, ok := <-watcher.Events:
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if !ok {
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return
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}
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log.Println("event:", event)
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if event.Op&fsnotify.Write == fsnotify.Write {
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log.Println("modified file:", event.Name)
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}
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case err, ok := <-watcher.Errors:
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if !ok {
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return
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}
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log.Println("error:", err)
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}
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}
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}()
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err = watcher.Add("/tmp/foo")
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if err != nil {
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log.Fatal(err)
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}
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<-done
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}
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```
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## Contributing
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Please refer to [CONTRIBUTING][] before opening an issue or pull request.
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## Example
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See [example_test.go](https://github.com/fsnotify/fsnotify/blob/master/example_test.go).
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## FAQ
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**When a file is moved to another directory is it still being watched?**
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No (it shouldn't be, unless you are watching where it was moved to).
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**When I watch a directory, are all subdirectories watched as well?**
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No, you must add watches for any directory you want to watch (a recursive watcher is on the roadmap [#18][]).
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**Do I have to watch the Error and Event channels in a separate goroutine?**
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As of now, yes. Looking into making this single-thread friendly (see [howeyc #7][#7])
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**Why am I receiving multiple events for the same file on OS X?**
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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][]).
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**How many files can be watched at once?**
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There are OS-specific limits as to how many watches can be created:
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* Linux: /proc/sys/fs/inotify/max_user_watches contains the limit, reaching this limit results in a "no space left on device" error.
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* BSD / OSX: sysctl variables "kern.maxfiles" and "kern.maxfilesperproc", reaching these limits results in a "too many open files" error.
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**Why don't notifications work with NFS filesystems or filesystem in userspace (FUSE)?**
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fsnotify requires support from underlying OS to work. The current NFS protocol does not provide network level support for file notifications.
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[#62]: https://github.com/howeyc/fsnotify/issues/62
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[#18]: https://github.com/fsnotify/fsnotify/issues/18
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[#11]: https://github.com/fsnotify/fsnotify/issues/11
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[#7]: https://github.com/howeyc/fsnotify/issues/7
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[contributing]: https://github.com/fsnotify/fsnotify/blob/master/CONTRIBUTING.md
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## Related Projects
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* [notify](https://github.com/rjeczalik/notify)
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* [fsevents](https://github.com/fsnotify/fsevents)
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