如何创建golang热文件夹只修改一次文件

Question

我有一个程序正在输出文件的情况。为了修复文件，我必须更改一行文本。我不拥有该程序的源代码，因此我必须更改该程序吐出的每个文件，以便其他程序可以正确使用它。由于该过程的性质，我无法重命名文件或移动它们。因此，我希望看到任何放入的新文件（通过循环和睡眠很容易）并更改文件，但只执行一次，因为其他进程需要出现并使用此文件。我在 Go 中编写了许多类似的应用程序，但总是被允许移动文件。

Answer 1

下面是我想出的代码： 接受有关如何使用 Seeker 执行此操作的建议，因为我只删除文件中的一行文本。

package main

import (

    "time"

    "fmt"       

    "io/ioutil"

    "os"

    "bytes"

    "strings"

)

const dir = "dir00003"

func main() {

fmt.Println("Running...")

//Go into a loop forever

for {

    //Wait 60 seconds before taking any action. 

    time.Sleep(60 * time.Second)

    //Read all of the file data for all files in the directory: 

    files, err := ioutil.ReadDir(dir)

    if err != nil {fmt.Println("Failed to read transfer folder. There must be a folder named `dir00003`!"); continue}

    for _, v := range files {

        //if this is an index file, skip over it as we don't care: 

        if strings.Contains(v.Name(), "pmi") {continue}

        //if the file was created within the last 2 minutes, we should check if we need to modify it

        if time.Now().Sub(v.ModTime()) < (time.Minute * 2) {

            //open the file 

            f, err := os.Open(fmt.Sprintf("%s/%s", dir, v.Name()))

            if err != nil {fmt.Printf("\tCouldn't open file: %s\n", v.Name()); continue}

            defer f.Close()

            //read all of the bytes of the file

            bs, err := ioutil.ReadAll(f)

            if err != nil {fmt.Printf("\tCouldn't read bytes from %s\n", v.Name()); continue}

            //see if the <program_parameters/> tag is in the file

            b := bytes.Contains(bs, []byte("<program_parameters/>"))

            //if the tag is in the file, we should replace it, otherwise we move on to the next file

            if b {

                //replace the tag with nothing. Only look for the first instance and then abort the process of replacing.

                rbs := bytes.Replace(bs, []byte("<program_parameters/>"), []byte(""), 1)

                //close the file so we can delete it. 

                f.Close()

                //delete the exisint file. 

                os.Remove(fmt.Sprintf("%s/%s", dir, v.Name()))

                //create a new file with the same original name:

                nf, err := os.Create(fmt.Sprintf("%s/%s", dir, v.Name()))

                if err != nil {fmt.Printf("\tFailed to create new file for %s\n", v.Name()); continue}

                //write all of the bytes that we have in memory to our new file. 

                _, err = nf.Write(rbs)

                if err != nil {fmt.Println("Failed to write to new file %s\n", v.Name()); continue}

                //close our new file

                nf.Close()

                fmt.Printf("Modified new file: %s", v.Name())

            } else {

                continue

            }

        }

    

    }

    fmt.Printf("\nDone with round\n")

}

fmt.Println("PROGRAM STOPPED RUNNING!!")

return 

}