#include <unistd.h>
#include <fcntl.h>
#include <stdint.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/wait.h>
#include <inttypes.h>
#include <sched.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdbool.h>

int main(int argc, char* argv[]) {
    int cmd_num = 1;
    int in_pair[2];
    int out_pair[2];
    pipe(in_pair);
    pipe(out_pair);
    while (cmd_num != argc) {
        pid_t pid = fork();
        if (pid == 0) {
            if (cmd_num != 1) {
                dup2(in_pair[0], 0);
                close(in_pair[0]);
                close(in_pair[1]);
            }
            if (cmd_num != argc - 1) {
                dup2(out_pair[1], 1);
                close(out_pair[1]);
            }
            execlp(argv[cmd_num], argv[cmd_num], NULL);
            perror("failed to execlp");
            exit(1);
        } else {
            close(in_pair[0]);
            close(in_pair[1]);
            int child_state;
            waitpid(pid, &child_state, 0);

            if (cmd_num == argc - 1) {
                return 0;
            }
            in_pair[0] = out_pair[0];
            in_pair[1] = out_pair[1];
            pipe(out_pair);
            ++cmd_num;
        }
    }
    return 0;
}