#include <iostream>
#include <unistd.h>
#include <sys/wait.h>

using namespace std;

int main(){

    pid_t mypid{getpid()};

    cout << "The parent has pid " << mypid << endl;

    // fork a process and exit.
    // this will be a zombie until the parent calls wait
    pid_t zombie{fork()};
    if (zombie == 0) {
        mypid = getpid();
        cout  << "\tThe child has pid " << mypid << endl;
        usleep(1000);
        cout << "\tThe child will exit " << endl;
        return 0;
    }

    usleep(100000);
    cout << "Parent waking up" << endl;

    cout << "Enter to continue " ;
    cin.ignore(1000,'\n');
 
    string fileName{"/proc/"+to_string(zombie)+"/status"};

    pid_t forked{fork()};
    if (forked == 0) {
        cout << "\tNew Child running head -4 " << fileName << endl; 
        execl("/usr/bin/head", "head", "-4", fileName.c_str(), nullptr);
        perror("\texecl");
        return 1;
    }

    int loc;

    cout << " Parent waiting on " << forked << endl;
    waitpid(forked, &loc, 0);

    cout << " Parent waiting on " << zombie << endl;
    waitpid(zombie, &loc, 0);
    wait(&loc);
    return 0;
}