Example of setting a watch on modifications of a given file

file_update.go

package main

import (
	"log"
	"os"
	"time"
)

func getLastModTime(filename string) time.Time {
	fileInfo, err := os.Stat(filename)
	if err != nil {
		log.Fatal(err)
	}
	return fileInfo.ModTime()
}

func NewFileWatcher(filename string, frequency time.Duration) chan time.Time {
	c := make(chan time.Time)
	go func() {
		var lastMod time.Time = time.Now()
		tick := time.Tick(frequency)
		for _ = range tick {
			currentMod := getLastModTime(filename)
			if currentMod.After(lastMod) {
				c <- currentMod
				lastMod = currentMod
			}
		}
	}()
	return c
}

func main() {
	watcher := NewFileWatcher("file_update.go", time.Second*5)
	for t := range watcher {
		log.Println("File updated! ", t)
	}
}