void setup_pipe(int fd[2], int used, int unused);

int main()
{
    while (true)
    {
        std::string com1, com2;
        std::cout << "Enter command 1 (incl. args) or quit: ";
        std::getline(std::cin, com1);
        if(com1 == "quit") return EXIT_SUCCESS;

        std::cout << "Enter command 2 (incl. args) : ";
        std::getline(std::cin, com2);

        int fd[2];
        if(pipe(fd) == -1)
        {
            perror("pipe");
            exit(EXIT_FAILURE);
        }

        pid_t pid;
        if((pid = fork()) == -1)
        {
            perror("fork");
            exit(EXIT_FAILURE);
        }

        if(pid == 0)//child 1
        {
            setup_pipe(fd, 1, 0);
            //std::cout << "child running com1 " << com1 <<std::endl;//DBG
            if(execlp(com1.c_str(), com1.c_str(), nullptr) == -1)
            {
                perror("execlp");
                exit(EXIT_FAILURE);
            }
        }
        else//parent
        {
            setup_pipe(fd, 0, 1);
            if((pid = fork()) == -1)
            {
                perror("fork");
                exit(EXIT_FAILURE);
            }

            if(pid == 0)//child 2
            {
                //setup_pipe(fd, 0, 1);
                //std::cout << "child running com2 " << com2 <<std::endl;//DBG
                if(execlp(com2.c_str(), com2.c_str(), nullptr) == -1)
                {
                    perror("execlp");
                    exit(EXIT_FAILURE);
                }
            }
            else//parent
            {
                wait(NULL);
                wait(NULL);
              //  std::cout << "parent done" <<std::endl;//DBG
            }
        }
        std::cin.ignore (std::numeric_limits<std::streamsize>::max(), '\n');

    }
}

void setup_pipe(int fd[2], int used, int unused)
{
    close(fd[unused]);
    close(used);
    dup(fd[used]);
    close(fd[used]);
}