donglu7816 2019-08-21 16:18
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如何隐藏终端命令的输出

I have a complex ffmpeg command to execute and I need to execute using Go. The command is working, the problem is coming when I try to hide the output of command using > /dev/null 2>&1

This is my code:

cmd := exec.Command(
    "ffmpeg",
    "-y",
    "-loglevel", "warning",
    "-i", ConvertImage,
    "-i", videoInput,
    "-c:v", cv,
    "-c:a", audioCodec,
    "-crf", fmt.Sprintf("%d", crf),
    "-map", "[v]",
    "-map", "1:a?",
    "-r", fmt.Sprintf("%d", Res.FrameRate),
    "-strict",
    "-2",
    outputFile,
    "> /dev/null 2>&1",
)

Without last field "> /dev/null 2>&1", code is working ok when I try to hide the output of command, command skip without the run.

What did I do wrong? How can I fix it?

  • 写回答

1条回答 默认 最新

  • douding7189 2019-08-21 17:39
    关注

    You can simply put the output to a bytes.Buffer variable like following:

    cmd := exec.Command(
        "ffmpeg",
        "-y",
        "-loglevel", "warning",
        "-i", ConvertImage,
        "-i", videoInput,
        "-c:v", cv,
        "-c:a", audioCodec,
        "-crf", fmt.Sprintf("%d", crf),
        "-map", "[v]",
        "-map", "1:a?",
        "-r", fmt.Sprintf("%d", Res.FrameRate),
        "-strict",
        "-2",
        outputFile,
    )
    
    var execOut bytes.Buffer
    var execErr bytes.Buffer
    cmd.Stdout = &execOut
    cmd.Stderr = &execErr
    

    By doing this, both the output and the error are in the corresponding buffer.

    Now, if you want to print them, then you can use the following code snippet along with the above code:

    err := cmd.Run()
    if err != nil {
        fmt.Println("Cannot Execute cmd: ", err.Error())
    }
    outStr := execOut.String()
    errStr := execErr.String()
    if len(outStr) > 0 {
        fmt.Print(outStr)
    }
    if len(errStr) > 0 {
        fmt.Print(errStr)
    }
    

    Update: Or, if you do not need the stdout and stderr totally, then you can set the cmd.Stdout and cmd.Stderr to nil just like following:

    cmd.Stdout = nil
    cmd.Stderr = nil
    
    err := cmd.Run()
    if err != nil {
        fmt.Println("Cannot Execute cmd: ", err.Error())
    }
    
    本回答被题主选为最佳回答 , 对您是否有帮助呢?
    评论

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