c 信号处理

1. 使用signal(int signal, function)向内核注册信号处理函数

2. 使用raise()向本进程发送信号，通过kill()向其他进程发送信号

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

void signal_handle(int signal);

int main(int argc, char **argv) {
    signal(SIGUSR1, signal_handle);

    int cpid, ppid;
    if ((cpid = fork()) == 0) {
        ppid = getppid();
        cpid = getpid();
        printf("cid:%d, ppid:%d\n", cpid, ppid);
        kill(ppid, SIGUSR1);
        printf("send signal to parent\n");
    } else {
        int pid = wait(NULL);
        printf("pid after wait:%d\n", pid);
    }
}

void signal_handle(int signal) {
    printf("receive signal:%d\n", signal);
}