Execute batch script from .NET (unexpected output)

Question

I'm trying to execute a simple batch script from a C# program.

Here's a minimal example:

Batch file

TIMEOUT /T 30 >nul
EXIT /B 1

C# program

    static void Main(string[] args)
    {
        Process process = new Process();
        process.StartInfo.UseShellExecute = false;
        process.StartInfo.RedirectStandardOutput = true;
        process.StartInfo.CreateNoWindow = false;
        process.StartInfo.FileName = "D:\\xxx.bat";
        process.Start();
        string output = process.StandardOutput.ReadToEnd();
        bool exit = process.WaitForExit(120000);
        Console.WriteLine(output);
    }

Output

"\r\nC:\\Users\\xxx\\bin\\Debug>TIMEOUT /T 30 \r\n\r\nWaiting for 30 seconds, press a key to continue ...\r\n\r\nC:\\Users\\xxx\\bin\\Debug>EXIT /B 1 \r\n"

I'd expect the batch script to produce no output (due to nul redirection of the timeout command) but it still does. The output contains the program path and the command text. Why is that? (Is it outputting the script trace eg. like bash -x? Google doesn't tell me how/if it could be disabled)

Community · Accepted Answer · 2020-06-20 09:12:55Z

1

Redirecting output to nul should only have hidden the output of the redirected command.

Instead, you can add @echo off at the start of your bat file.

This will:

_{From "Echo", Technet}

prevent all commands in a batch file (including the echo off command) from displaying on the screen.

edited Jun 20, 2020 at 9:12

CommunityBot

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answered Sep 29, 2015 at 6:53

Helix Quar

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