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

#define BUFSZ PIPE_BUF

void err_quit(char *msg);

int main (void){

FILE *fp;
char *cmdstring = "cat pipopn.c";
char buf[BUFSZ];

if((fp = popen(cmdstring, "r"))==NULL){
    err_quit("popen");
}
while((fgets(buf,BUFSZ,fp))!=NULL)
    printf("$s",buf);

pclose(fp);
exit(EXIT_SUCCESS);
}

void err_quit(char *msg){
    perror(msg);
    exit(EXIT_FAILURE);
}