#include <unistd.h>
#include <stdio.h>
#include <stdlib.h>
#include <fcntl.h>
#include <sys/wait.h>

int main()
{
    const char *cmd = "./my_prog.pl";
    const int RESPONSE_FD = 63;
    int pfd[2], status;
    char buffer[100];
    int rv;

    status = pipe(pfd);
    if(status == -1)
    {
        printf("Could not open pipe\n");
        exit(1);
    }
    else
    {
        printf("The filedescriptors are: %d %d\n", pfd[0], pfd[1]);
    }

    status = fork();
    if(status == 0)
    {
        printf("This is the child\n");
        /* dup output/writing side of pipe */
        status = dup2(pfd[1], RESPONSE_FD);
        /* close unused input side */
        close(pfd[0]);
        if(status == -1)
        {
            printf("dup2 failed\n");
            exit(1);
        }
        execl(cmd, cmd, (char *)0);
    }
    else
    {
        printf("This is the parent\n");
        /* close unused output side of pipe */
        close(pfd[1]);
        /* read from input side */
        while(read(pfd[0], buffer, sizeof(buffer))>0)
        {
            printf("%s", buffer);
        }
        wait(&rv);
        fprintf(stderr,"%s exited with value %d\n", cmd, rv);
    }
    return 0;
}

##</code><code>##

The filedescriptors are: 4 6
This is the child
This is the parent
this is a message
./my_prog.pl exited with value 0