relibc/tests/pipe.c

//http://www2.cs.uregina.ca/~hamilton/courses/330/notes/unix/pipes/pipes.html
#include <unistd.h>

int main()
{

    int pid, pip[2];
    char instring[20];

    pipe(pip); 

    pid = fork();
    if (pid == 0)           /* child : sends message to parent*/
    {
        /* send 7 characters in the string, including end-of-string */
        write(pip[1], "Hi Mom!", 7);  
    }
    else			/* parent : receives message from child */
    {
        /* read from the pipe */
        read(pip[0], instring, 7);
    }
}