将输出送到管道

#include <unistd.h>
#include <stdlib.h>
#include <stdio.h>
int main()
{
    FILE *write_fp;
    char buffer[BUFSIZ+1];
    sprintf(buffer,"Once upon a time,there was...\n");
    write_fp=popen("od -c","w");
    if(write_fp=NULL)
    {
        fwrite(buffer,sizeof(char),strlen(buffer),write_fp);
        pclose(write_fp);
        exit(EXIT_SUCCESS);
    }
    exit(EXIT_FAILURE);
}