child and parent process id

c, fork, pid

Solution

That's because the father can / will exit before the son. If a father exists without having requested the return value of it's child, the child will get owned by the process with pid=1. What is on classic UNIX or GNU systems SystemV init.

The solution is to use `waitpid()` in father:

int main(int argc, char *argv[])
{
    pid_t pid;
    pid=fork();
    if(pid==-1){
        perror("fork failure");
        exit(EXIT_FAILURE);
    }
    else if(pid==0){
        printf("pid in child=%d and parent=%d\n",getpid(),getppid()); 
    }
    else{
        printf("pid in parent=%d and childid=%d\n",getpid(),pid);
    }

    int status = -1;
    waitpid(pid, &status, WEXITED);

    printf("The child exited with return code %d\n", status);
    exit(EXIT_SUCCESS);
}

Problem

Just got confused with parent pid value in child process block. My program is given below: ``` int main(int argc, char *argv[]) { pid_t pid; pid=fork(); if(pid==-1){ perror("fork failure"); exit(EXIT_FAILURE); } else if(pid==0){ printf("pid in child=%d and parent=%d\n",getpid(),getppid()); } else{ printf("pid in parent=%d and childid=%d\n",getpid(),pid); } exit(EXIT_SUCCESS); } ``` Output: pid in parent=2642 and childid=2643 pid in child=2643 and parent=1 In "Advanced Unix programming" it says that child process can get parent process id using getppid() function. But here I am getting "1" which is "init" process id. How can I get the parent pid value in the child process block.. Please help me in getting output. I executed in "Linux Mint OS" but in "WindRiver" OS I am not getting this problem. Does this program change behaviour according to OS?

Original source

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