如何在 C# 控制台应用程序中捕获 ctrl-c (SIGINT)

Question

我希望能够在 C# 控制台应用程序中捕获 CTRL+C 以便我可以在退出之前进行一些清理。这样做的最佳方法是什么？

Answer 1

Console.CancelKeyPress 事件用于此目的。它是这样使用的：

public static void Main(string[] args)
{
    Console.CancelKeyPress += delegate {
        // call methods to clean up
    };

    while (true) {}
}

当用户按下 Ctrl + C 时，委托中的代码运行并且程序退出。这允许您通过调用必要的方法来执行清理。注意委托执行后没有代码。

在其他情况下这不会削减它。例如，如果程序当前正在执行无法立即停止的重要计算。在这种情况下，正确的策略可能是在计算完成后告诉程序退出。以下代码给出了如何实现的示例：

class MainClass
{
    private static bool keepRunning = true;

    public static void Main(string[] args)
    {
        Console.CancelKeyPress += delegate(object sender, ConsoleCancelEventArgs e) {
            e.Cancel = true;
            MainClass.keepRunning = false;
        };
        
        while (MainClass.keepRunning) {
            // Do your work in here, in small chunks.
            // If you literally just want to wait until ctrl-c,
            // not doing anything, see the answer using set-reset events.
        }
        Console.WriteLine("exited gracefully");
    }
}

这段代码和第一个例子的不同之处在于e.Cancel被设置为true，这意味着在delegate之后继续执行。如果运行，程序会等待用户按 Ctrl + C。当这种情况发生时，keepRunning 变量会更改值，这会导致 while 循环退出。这是一种让程序优雅退出的方法。

Answer 2

参见 MSDN：

Console.CancelKeyPress Event

带有代码示例的文章：

Ctrl-C and the .NET console application

Answer 3

我想添加到Jonas' answer。在bool 上旋转将导致 100% 的 CPU 利用率，并在等待 CTRL+C 时浪费大量精力。

更好的解决方案是使用ManualResetEvent 实际“等待” CTRL+C：

static void Main(string[] args) {
    var exitEvent = new ManualResetEvent(false);

    Console.CancelKeyPress += (sender, eventArgs) => {
                                  eventArgs.Cancel = true;
                                  exitEvent.Set();
                              };

    var server = new MyServer();     // example
    server.Run();

    exitEvent.WaitOne();
    server.Stop();
}

Answer 4

这是一个完整的工作示例。粘贴到空的 C# 控制台项目中：

using System;
using System.Collections.Generic;
using System.Linq;
using System.Runtime.InteropServices;
using System.Text;
using System.Threading;

namespace TestTrapCtrlC {
    public class Program {
        static bool exitSystem = false;

        #region Trap application termination
        [DllImport("Kernel32")]
        private static extern bool SetConsoleCtrlHandler(EventHandler handler, bool add);

        private delegate bool EventHandler(CtrlType sig);
        static EventHandler _handler;

        enum CtrlType {
            CTRL_C_EVENT = 0,
            CTRL_BREAK_EVENT = 1,
            CTRL_CLOSE_EVENT = 2,
            CTRL_LOGOFF_EVENT = 5,
            CTRL_SHUTDOWN_EVENT = 6
        }

        private static bool Handler(CtrlType sig) {
            Console.WriteLine("Exiting system due to external CTRL-C, or process kill, or shutdown");

            //do your cleanup here
            Thread.Sleep(5000); //simulate some cleanup delay

            Console.WriteLine("Cleanup complete");

            //allow main to run off
            exitSystem = true;

            //shutdown right away so there are no lingering threads
            Environment.Exit(-1);

            return true;
        }
        #endregion

        static void Main(string[] args) {
            // Some biolerplate to react to close window event, CTRL-C, kill, etc
            _handler += new EventHandler(Handler);
            SetConsoleCtrlHandler(_handler, true);

            //start your multi threaded program here
            Program p = new Program();
            p.Start();

            //hold the console so it doesn’t run off the end
            while (!exitSystem) {
                Thread.Sleep(500);
            }
        }

        public void Start() {
            // start a thread and start doing some processing
            Console.WriteLine("Thread started, processing..");
        }
    }
}

Answer 5

这个问题非常类似于：

Capture console exit C#

这是我解决这个问题的方法，并处理了用户按 X 和 Ctrl-C 的问题。注意 ManualResetEvents 的使用。这些将导致主线程休眠，从而释放 CPU 以在等待退出或清理时处理其他线程。注意：有必要在 main 结束时设置 TerminationCompletedEvent。如果不这样做，则会由于操作系统在终止应用程序时超时而导致不必要的终止延迟。

namespace CancelSample
{
    using System;
    using System.Threading;
    using System.Runtime.InteropServices;

    internal class Program
    {
        /// <summary>
        /// Adds or removes an application-defined HandlerRoutine function from the list of handler functions for the calling process
        /// </summary>
        /// <param name="handler">A pointer to the application-defined HandlerRoutine function to be added or removed. This parameter can be NULL.</param>
        /// <param name="add">If this parameter is TRUE, the handler is added; if it is FALSE, the handler is removed.</param>
        /// <returns>If the function succeeds, the return value is true.</returns>
        [DllImport("Kernel32")]
        private static extern bool SetConsoleCtrlHandler(ConsoleCloseHandler handler, bool add);

        /// <summary>
        /// The console close handler delegate.
        /// </summary>
        /// <param name="closeReason">
        /// The close reason.
        /// </param>
        /// <returns>
        /// True if cleanup is complete, false to run other registered close handlers.
        /// </returns>
        private delegate bool ConsoleCloseHandler(int closeReason);

        /// <summary>
        ///  Event set when the process is terminated.
        /// </summary>
        private static readonly ManualResetEvent TerminationRequestedEvent;

        /// <summary>
        /// Event set when the process terminates.
        /// </summary>
        private static readonly ManualResetEvent TerminationCompletedEvent;

        /// <summary>
        /// Static constructor
        /// </summary>
        static Program()
        {
            // Do this initialization here to avoid polluting Main() with it
            // also this is a great place to initialize multiple static
            // variables.
            TerminationRequestedEvent = new ManualResetEvent(false);
            TerminationCompletedEvent = new ManualResetEvent(false);
            SetConsoleCtrlHandler(OnConsoleCloseEvent, true);
        }

        /// <summary>
        /// The main console entry point.
        /// </summary>
        /// <param name="args">The commandline arguments.</param>
        private static void Main(string[] args)
        {
            // Wait for the termination event
            while (!TerminationRequestedEvent.WaitOne(0))
            {
                // Something to do while waiting
                Console.WriteLine("Work");
            }

            // Sleep until termination
            TerminationRequestedEvent.WaitOne();

            // Print a message which represents the operation
            Console.WriteLine("Cleanup");

            // Set this to terminate immediately (if not set, the OS will
            // eventually kill the process)
            TerminationCompletedEvent.Set();
        }

        /// <summary>
        /// Method called when the user presses Ctrl-C
        /// </summary>
        /// <param name="reason">The close reason</param>
        private static bool OnConsoleCloseEvent(int reason)
        {
            // Signal termination
            TerminationRequestedEvent.Set();

            // Wait for cleanup
            TerminationCompletedEvent.WaitOne();

            // Don't run other handlers, just exit.
            return true;
        }
    }
}

Answer 6

Console.TreatControlCAsInput = true; 为我工作。

Answer 7

我可以在退出前进行一些清理工作。这样做的最佳方法是什么 这才是真正的目标：陷阱出口，制作自己的东西。上面的答案都没有正确。因为，Ctrl+C 只是退出应用的众多方式之一。

dotnet c# 中需要什么 - 所谓的 取消令牌 传递给 Host.RunAsync(ct)，然后，在退出信号陷阱中，对于 Windows，它将是

    private static readonly CancellationTokenSource cts = new CancellationTokenSource();
    public static int Main(string[] args)
    {
        // For gracefull shutdown, trap unload event
        AppDomain.CurrentDomain.ProcessExit += (sender, e) =>
        {
            cts.Cancel();
            exitEvent.Wait();
        };

        Console.CancelKeyPress += (sender, e) =>
        {
            cts.Cancel();
            exitEvent.Wait();
        };

        host.RunAsync(cts);
        Console.WriteLine("Shutting down");
        exitEvent.Set();
        return 0;
     }

...

Answer 8

检测 SIGTERM 和 ctrl+c:

CancellationTokenSource ctSource = new();
CancellationToken ct = ctSource.Token;

void ExitHandler()
{
    // You can add any arbitrary global clean up
    Console.WriteLine("Exiting...");
    ctSource.Cancel();
}

// Assign exit handler to be called when the process is terminated
// or the user hits CTRL+C
AppDomain.CurrentDomain.ProcessExit += (sender, args) => ExitHandler();
Console.CancelKeyPress += (sender, args) => ExitHandler();

// Then you can use the cancellation token to check for exit:
Console.WriteLine("Ready to gracefully shut down!");
while (!ct.IsCancellationRequested)
{
    Console.WriteLine($"Exit not detected, waiting another 10s.");
    Task.Delay(10000, ct).Wait(ct);
}

Answer 9

在我的例子中，我将一个异步 lambda 传递给 Console.CancelKeyPress，但这是行不通的。