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缘由：

之前在Linux下使用过inotify-tools来获知文件的变化情况，在博客里也记录了几篇文章，现在在学习Go 语言，也想了解一下在Go 语言中如何实现类似的功能。

正文：

参考解答：

一个跨平台的简单版实现，来自 this.lau_：

package main

import (
    "fmt"
    "os"
    "time"
)

func watchFile(filePath string) error {
    initialStat, err := os.Stat(filePath)
    if err != nil {
        return err
    }

    for {
        stat, err := os.Stat(filePath)
        if err != nil {
            return err
        }

        if stat.Size() != initialStat.Size() || stat.ModTime() != initialStat.ModTime() {
            break
        }

        time.Sleep(1 * time.Second)
    }

    return nil
}

func main() {
    doneChan := make(chan bool)

    go func(doneChan chan bool) {
        defer func() {
            doneChan <- true
        }()

        err := watchFile("/private/tmp/test")
        if err != nil {
            fmt.Println(err)
        }

        fmt.Println("File has been changed")
    }(doneChan)

    <-doneChan
}

---

使用 fsnotify 包的官方用例：

package main

import (
    "github.com/fsnotify/fsnotify"
    "log"
)

func ExampleNewWatcher() {
    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("/private/tmp/foo")
    if err != nil {
        log.Fatal(err)
    }
    <-done
}

func main() {
    ExampleNewWatcher()
}

 

参考链接：

• Go language how detect file changing?
• Cross-platform file system notifications for Go.
  https://github.com/fsnotify/fsnotify/blob/master/example_test.go
• https://golang.org/pkg/os/#FileInfo
• https://golang.org/pkg/os/#File.Seek

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