pipedemo.c

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

int main() 
{
    int len, i, apipe[2];
    char buf[BUFSIZ];

    if( pipe(apipe) == -1 ) {
        perror("could not make pipe");
        exit(1);
    }

    printf("Got a pipe! It is file description : {%d %d}\n", apipe[0], apipe[1]);

    while(fgets(buf, BUFSIZ, stdin)) {
        len = strlen(buf);

        if(write(apipe[1], buf, len) != len) {
            perror("writing to pipe");
            break;
        }

        for(i = 0; i < len; i++) {
            buf[i] = 'X';
        }

        len = read(apipe[0], buf, BUFSIZ);
        if(len == -1) {
            perror("reading from pipe");
            break;
        }
        if(write(1, buf, len) != len) {
            perror("writing to stdout");
            break;
        }
    }
}