FileWatcher

package main

import (
    "bytes"
    "flag"
    "github.com/go-fsnotify/fsnotify"
    "log"
    "os/exec"
    "strings"
)

var watch_path = flag.String("path", "", "监控的目录")
var cmd = flag.String("cmd", "", "要执行的命令")
var suffix = flag.String("suffix", ".mmd", "监控文件后缀")

func main() {
    flag.Parse()
    watcher, err := fsnotify.NewWatcher()
    if err != nil {
        log.Fatal(err)
    }

    defer watcher.Close()

    done := make(chan bool)
    go func() {
        for {
            select {
            case event := <-watcher.Events:
                log.Println(event)
                if event.Op&fsnotify.Write == fsnotify.Write {
                    if strings.HasSuffix(event.Name, *suffix) {
                        log.Println("modified file: ", event.Name)
                        //cmd_to_exec := "/usr/local/bin/mermaid -w 1200 -t" + watch_path + "/mermaid.css -g " + watch_path + "/config.json -o " + watch_path + "/output " + event.Name
                        //cmd_to_exec := fmt.Sprintf(*cmd, event.Name)
                        cmd_to_exec := strings.Replace(*cmd, "[filename]", event.Name, -1)
                        cmd_to_exec = strings.Replace(cmd_to_exec, "[path]", *watch_path, -1)
                        log.Println("cmd to execute: ", cmd_to_exec)

                        cmd := exec.Command("sh", "-c", cmd_to_exec)
                        var out_stdout bytes.Buffer
                        var out_stderr bytes.Buffer
                        cmd.Stderr = &out_stderr
                        cmd.Stdout = &out_stdout
                        err := cmd.Run()
                        if err != nil {
                            log.Println("command execute failed: ", err)
                        }
                        log.Println(out_stdout.String())
                        if out_stderr.Len() > 0 {
                            log.Println("Error: ", out_stderr.String())
                        }
                    }

                }
            case err := <-watcher.Errors:
                log.Println("error:", err)
            }
        }
    }()

    err = watcher.Add(*watch_path)
    if err != nil {
        log.Fatal(err)
    }
    log.Println("watching directory: " + *watch_path)

    <-done
}

https://github.com/mylxsw/FileWatcher/blob/master/watcher.go