c# - Windows 服务更改批处理文件中回显/流重定向的行为

Question

创建 Windows 批处理文件 c:\test\first.bat:

@echo off
echo A
call second.bat < empty.txt
echo B
echo C

和两个空文件 c:\test\second.bat 和 c:\test\empty.txt(如果它们不为空，也会发生同样的情况。)

先运行.bat。正如预期的那样，输出是

A
B
C

现在，不直接运行批处理文件，而是创建一个 C# 命令行应用程序:

using System.Collections.Concurrent;
using System.Diagnostics;
using System.IO;

namespace ConsoleApplication1
{
    class Program
    {
        static void Main(string[] args)
        {
            var processInfo = new ProcessStartInfo("cmd.exe", @"/c c:\test\first.bat");
            processInfo.CreateNoWindow = true;
            processInfo.UseShellExecute = false;
            processInfo.RedirectStandardError = true;
            processInfo.RedirectStandardOutput = true;
            var process = new Process();
            process.EnableRaisingEvents = true;
            var log = new BlockingCollection<string>();
            process.OutputDataReceived += (sender, e) => log.Add(e.Data);
            process.Exited += (sender, e) =>
            {
                process.Dispose();
                File.WriteAllText(@"c:\test\log.txt", string.Join("\n", log));
            };
            process.StartInfo = processInfo;
            process.Start();
            process.BeginOutputReadLine();
            process.BeginErrorReadLine();

            process.WaitForExit();
        }
    }
}

同样，正如预期的那样，文件 c:\test\log.txt 被创建并包含

A
B
C

现在，创建 Windows 服务而不是命令行应用程序:

using System.Collections.Concurrent;
using System.Diagnostics;
using System.IO;
using System.ServiceProcess;

namespace WindowsService1
{
    public partial class Service1 : ServiceBase
    {
        public Service1()
        {
            InitializeComponent();
            this.CanStop = true;
        }

        protected override void OnStart(string[] args)
        {
            var processInfo = new ProcessStartInfo("cmd.exe", @"/c c:\test\first.bat");
            processInfo.CreateNoWindow = true;
            processInfo.UseShellExecute = false;
            processInfo.RedirectStandardError = true;
            processInfo.RedirectStandardOutput = true;
            var process = new Process();
            process.EnableRaisingEvents = true;
            var log = new BlockingCollection<string>();
            process.OutputDataReceived += (sender, e) => log.Add(e.Data);
            process.Exited += (sender, e) =>
            {
                process.Dispose();
                File.WriteAllText(@"c:\test\slog.txt", string.Join("\n", log));
            };
            process.StartInfo = processInfo;
            process.Start();
            process.BeginOutputReadLine();
            process.BeginErrorReadLine();
        }

        protected override void OnStop()
        {
        }
    }
}

安装并启动服务(允许对所有相关文件授予所需的权限)。(使用哪个帐户(User、Local Service、Local System ...)似乎并不重要。)

再次创建文件 c:\test\slog.txt，但现在它包含:

A
echo B
B
echo C
C

为什么？

---

(可能相关:如果first.bat中“echo C”后没有换行符，则slog.txt包含:

A
echo B
B
more?

为什么？)

Answer 1

(评论中提供的解决方案。转换为社区维基答案。参见 Question with no answers, but issue solved in the comments (or extended in chat))

@Gennadiy 写道:

Try to add processInfo.RedirectStandardInput = true;

OP 写道:

Yes, that makes the service behave more like I expected. Any idea why? Are there any downsides to using this?

@Harry Johnston 写道:

Looks like the batch processor runs into trouble when it doesn't have a valid standard input stream. I imagine the underlying problem occurs when it tries to set the standard input handle back to the original (invalid) value once the redirection to empty.txt is complete.