c - 在 SIGINT 之前打印消息

Question

#include <stdio.h>
#include <signal.h>
#include <stdlib.h>
#include <unistd.h>

/* A signal handling function that simply prints
   a message to standard error. */
void handler(int code) {
    fprintf(stderr, "Signal %d caught\n", code);
}

int main() {
    // Declare a struct to be used by the sigaction function:
    struct sigaction newact;

    // Specify that we want the handler function to handle the
    // signal:
    newact.sa_handler = handler;

    // Use default flags:
    newact.sa_flags = 0;

    // Specify that we don't want any signals to be blocked during
    // execution of handler:
    sigemptyset(&newact.sa_mask);

    // Modify the signal table so that handler is called when
    // signal SIGINT is received:
    sigaction(SIGINT, &newact, NULL);

    // Keep the program executing long enough for users to send
    // a signal:
    int i = 0;

    for (;;) {
        if ((i++ % 50000000) == 0) {
            fprintf(stderr, ".");
        }
    }

    return 0;
}

当我按下 ctrl-c 时，我希望我的程序打印 "Signal %d catch\n" 消息，然后正常退出，就像按下 ctrl-c 时一样。

./测试................................^CSignal 2 已捕获......................^CSignal 2 已捕获........................................^Z[2]+ 已停止./test

现在它只是打印消息，但不会立即退出程序。

Answer 1

这是因为ctrl+c的默认行为是退出程序。但是通过使用sigaction()，您可以自己管理行为。因此，如果您希望程序结束，可以添加 exit() 调用。

void handler(int code) {
    fprintf(stderr, "Signal %d caught\n", code);
    exit(code);
}