读取管道输入后接收用户输入 [英] Receiving user input after reading piped input

问题描述

我正在.NET 4中编写一个小型的交互式控制台应用程序。我想扩展它以便能够处理可选的重定向输入，例如：

I am writing a small, interactive console application in .NET 4. I want to extend this to be able to handle optional redirected input as well, like:

echo hello | myapp.exe

麻烦当然是重定向的输入窃取了键盘流，所以任何调用到Console.Read *（）返回null。

Trouble is of course that the redirected input steals the "keyboard stream", so any calls to Console.Read*() returns null.

目前我所拥有的是：

// Read piped input
try
{
    bool keyAvailable = Console.KeyAvailable;
}
catch
{
    string redirected = Console.In.ReadToEnd();
    // Need to do something here to "un-redirect" stdin back to keyboard
}

// Always returns null
String userInput = Console.ReadLine();

在UNIX上我可以打开一个到/ dev / tty的流来获取用户输入，但我怎么能在Windows上使这个工作？

On UNIX I could open a stream to /dev/tty to get user input, but how can I make this work on Windows?

谢谢！

基于Craig答案的工作解决方案：

[System.Runtime.InteropServices.DllImport("kernel32.dll")]
static extern bool AttachConsole(int dwProcessId);
[System.Runtime.InteropServices.DllImport("kernel32.dll")]
static extern bool FreeConsole();

try
{
     bool keyAvailable = Console.KeyAvailable;
}
catch
{
    string redirectedInput = Console.In.ReadToEnd();
    bool freed = FreeConsole();
    bool attached = AttachConsole(-1);
    Console.SetIn(new StreamReader(Console.OpenStandardInput()));
}

我必须首先使用

FreeConsole().

我可以选择使用

AllocConsole()

但这会产生另一个控制台窗口，我真的不想要。相反，我使用

but that would create another console window, which I don't really want. Instead I attach to the parent console (the existing cmd.exe) using

AttachConsole(-1) // -1 = "Parent".

我只能推测.NET类控制台保存对前一个stdin流的引用，但仅限于在调用 Console.SetIn（）后， Console.ReadLine（）回到它的阻塞行为，等待用户输入。

I can only speculate that the .NET class Console holds a reference to the previous stdin stream, but only after the call to Console.SetIn() the Console.ReadLine() is back to it's blocking behavior, waiting for user input.

现在开始调查如果我运行我的应用程序的stdout重定向会发生什么：

Now on to investigate what happens if I run with my application's stdout redirected:

echo hello | myapp.exe | somewhere ...

推荐答案

AttachConsole 功能应该可以完成这项工作，不过我只用它来重新获得输出而不是输入。

The AttachConsole function should do the job, though I've only used it to regain output rather than input.

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