File system notifications for Go
Cross platform: Windows, Linux, BSD and OS X.
Moving Notice
There is a fork being actively developed with a new API in preparation for the Go Standard Library: github.com/go-fsnotify/fsnotify
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)
}
// Hang so program doesn't exit
<-done
/* ... do stuff ... */
watcher.Close()
}
For each event:
- Name
- IsCreate()
- IsDelete()
- IsModify()
- IsRename()
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 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.