一个小的Linux程序，一运行电脑就自动关机。（要求两个进程轮流打印1.2.3.4....）

Question

#include
#include
#include
#include
#include

void f_sigact(int num)
{
static int f = 2;
// sleep(1);
printf("I am father.This is %d\n",f);
f += 2;
}

void c_sigact(int num)
{
int static c = 1;
// sleep(1);
printf("I am child.This is %d\n",c);
c+=2;
}

int main()
{
pid_t fpid,cpid;
struct sigaction fact,cact;
fact.sa_handler = f_sigact;
cact.sa_handler = c_sigact;
// sigemptyset(&fact.sa_mask);
// sigaddset(&fact.sa_mask,SIGUSR2);
fact.sa_flags = 0;
// sigaction(SIGUSR1,&fact,NULL);
// sigemptyset(&cact.sa_mask);
sigaddset(&cact.sa_mask,SIGUSR1);

cact.sa_flags = 0;
sigaction(SIGUSR2,&cact,NULL);

fpid = fork();
if(fpid < 0){
    perror("fork");
    exit(1);
}
int m = 5;
while(1){
    if(fpid > 0){
        kill(fpid,SIGUSR2);
//      sleep(1);
        }
    else{
        cpid = getppid();
        kill(cpid,SIGUSR1);
//      sleep(1);
    }
    sleep(3);
}

return 0;

}

Answer 1

#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <signal.h>
void f_sigact(int num)
{
        static int f = 2;
        // sleep(1);
        printf("I am father.This is %d\n",f);
        f += 2;
}
void c_sigact(int num)
{
        int static c = 1;
        // sleep(1);
        printf("I am child .This is %d\n",c);
        c+=2;
}
int main()
{
        pid_t fpid,cpid;
        struct sigaction fact,cact;
        struct sigaction ofact,ocact;
        fact.sa_handler = f_sigact;
        cact.sa_handler = c_sigact;
        // sigemptyset(&fact.sa_mask);
        // sigaddset(&fact.sa_mask,SIGUSR2);
        fact.sa_flags = 0;
        cact.sa_flags = 0;
        // sigaction(SIGUSR1,&fact,NULL);
        // sigemptyset(&cact.sa_mask);
        sigaddset(&cact.sa_mask,SIGUSR1);
        sigaddset(&fact.sa_mask,SIGUSR2);
        //sigaction(SIGUSR2,&cact,NULL);
        cpid = fork();
        if(cpid < 0){
                perror("fork");
                        exit(1);
        }
        else if (cpid==0){
                //it's a child
                sigaction(SIGUSR1,&cact,&ocact);
        }
        else{
                //it;s the parent
                sigaction(SIGUSR2,&fact,&ofact);
        }

        int m = 5;
        sleep(1);
        while(1){
                if (cpid>0)
                {
                        fpid = getpid();
                        kill(cpid,SIGUSR1);
                        sleep(1);
                        kill(fpid,SIGUSR2);
                        sleep(1);
                }
                        sleep(3);
        }

        return 0;
}