리눅스 파이프 관련

#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <math.h>
#include <fcntl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <unistd.h>
#include <signal.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <pthread.h>
#include <semaphore.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
 
/*
 
 ls -l | od -c | wc > out.txt
 
*/
 
 
 
#define MAX_LINE 100
//#############################################################################
int main(int argc, char **argv)
{
 
    int res, i;
 if (argc != 1)
 {
  printf("USAGE: ] ./ret \n");
  exit(0);
 }
 
    int data_processed;
    int file_pipes[2];
    pid_t fork_result;
 
    if (pipe(file_pipes) == 0) {
        fork_result = fork();
        if (fork_result == (pid_t)-1) {
            fprintf(stderr, "Fork failure");
            exit(EXIT_FAILURE);
        }
 
        if (fork_result == (pid_t)0) {
            close(0);
            dup(file_pipes[0]);
            close(file_pipes[0]);
            close(file_pipes[1]);
 
            execlp("od", "od", "-c", (char *)0);
            exit(EXIT_FAILURE);
        }
        else {
 
            close(1);
 
            dub(file_pipes[1]);
 
 
            close(file_pipes[0]);
            close(file_pipes[1]);
 
execlp("ls","ls","-l",(char *)0);
 
exit(EXIT_FAILURE);
 
         }
    }
    exit(EXIT_SUCCESS);
}
 
 
 
 printf("Execution finished successfully.... \n\n");
 
}