Why do processes I fork get systemd as their parent?

Question

I am learning fork() in Linux, and here is my program:

  1 #include 
  2 #include 
  3 #include 
  4 int main(         


        

Answer 1

It is because the parent process terminates first. In Linux there are no ophan processes. They are assigned to the init process.

If you want to control your processes so that child process terminates first, make parent process wait. Using wait() sys_call.

Example:

   #include 
   #include 
   #include 
   int main(void)
   {
        int pid;
        int pid2;
        pid = fork();
        if(pid < 0){
                 exit(1);
        }
        if(pid == 0){ // child process
            pid2 = fork()
            if (pid2 < 0)
                exit(1);
            if (pid2 == 0)
            {
                printf("pid:%dppid:%d\n",getpid(),getppid());
                exit(0);
            }
            wait();
            printf("pid:%d ppid:%d\n",getpid(),getppid());
            exit(0);
        }
        else{         // parent process
           wait();
           printf("parent pid:%d ppid:%d\n",getpid(),getppid());
           exit(0);
        }       
        return 0;            
  }

systemd is an init system used in Linux distributions to bootstrap the user space and manage all processes subsequently