Watch file changes inside a directory

watcher.go

package main

import (
	"fmt"
	"io/fs"
	"log"
	"os"
	"path/filepath"
	"github.com/fsnotify/fsnotify"
)

func main() {
	fileUpdated := make(chan string)

	go WatchEvents(fileUpdated)

	for f := range fileUpdated {
		fmt.Println("File updated:", f)
	}
}

//Create watcher event function that receives a channel to receive the current file changed
func WatchEvents(updateF chan<- string) {
	//Create a watcher to listen system events
	watcher, err := fsnotify.NewWatcher()
	if err != nil {
		log.Fatal(err)
	}

	//Mount directory path to watch, you can edit it
	path, _ := os.Getwd()
	directories := fmt.Sprintf("%s/root", path)

	//Use filepath to iterate in every file inside a directory
	err = filepath.WalkDir(directories, func(pathDir string, d fs.DirEntry, err error) error {
		if err != nil {
			log.Fatal(err)
			return err
		}
		if d.IsDir() {
			//Add file to watcher list
			err = watcher.Add(pathDir)

			if err != nil {
				log.Fatal(err)
			}
		}
		return nil
	})

	if err != nil {
		log.Fatal("Error in file path:", err.Error())
	}
	
	//Iterate over the Events channel to validate when a Write event occours
	for event := range watcher.Events {
		if event.Has(fsnotify.Write) {
			//insert the filename in the channel received when we create this function
			updateF <- event.Name
		}
	}
}