filePath:="./show.txt"
    copyFilepath:="./copy.txt"
    file,_:=os.Open(filePath)
    defer  file.Close()
    buf:=make([]byte,1024)
    for {
        _,err:=file.Read(buf)
        if err == io.EOF {
            break;
        }
        copyfile,_:= os.OpenFile(copyFilepath,os.O_APPEND|os.O_CREATE,666)//复制文件给另一个
        copyfile.Write(buf)
    }

    //读取文件第二种办法 bufio
    filePath:="./show.txt"
    file,_:=os.OpenFile(filePath,os.O_CREATE|os.O_APPEND,666)
    buf:=make([]byte,1024)
    newReader:=bufio.NewReader(file)
    n,_:=newReader.Read(buf)
    fmt.Println(string(buf[:n]))

    //读取文件第三中办法
    filePath:="./show.txt"
    buf,err:=ioutil.ReadFile(filePath)
    if err != nil {
        fmt.Println("read file is error")
    }
    fmt.Println(string(buf))