#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>

int main()
{
    int data_processed;
    int file_pipes[2];
    const char some_data[] = "123";
    int fork_result;

    if (pipe(file_pipes) == 0) {

        fork_result = fork();
        if (fork_result == -1) {
            fprintf(stderr, "Fork failure");
            exit(EXIT_FAILURE);
        }

        if (fork_result == 0) {
                /* This is the child process */
            close(0);
            dup(file_pipes[0]);
            close(file_pipes[0]);
            close(file_pipes[1]);            
                  
            execlp("od", "od", "-c", (char *)0);
            exit(EXIT_FAILURE);
        } else {
                /* This is the parent process */
            close(file_pipes[0]);            
            data_processed = write(file_pipes[1], some_data,
                                   strlen(some_data));
            close(file_pipes[1]);
            printf("%d - wrote %d bytes\n", getpid(), data_processed);
        }
    }
    exit(EXIT_SUCCESS);
}