#include <stdio.h>
#include <unistd.h>
#include <sys/types.h>

void main(){
    int fd[2];
    pid_t childpid;
    char    string[] = "Hello, world!\n";
        char    readbuffer[80];

    pipe(fd);
    if((childpid = fork()) == -1)
        {
                perror("fork");
                exit(1);
        }
        if(childpid == 0)
        {
                /* Child process closes up input side of pipe *
                close(fd[0]);

                /* Send "string" through the output side of pipe */
                write(fd[1], string, (strlen(string)+1));
                exit(0);
        }
        else
        {
                /* Parent process closes up output side of pipe */
                close(fd[1]);

                /* Read in a string from the pipe */
                nbytes = read(fd[0], readbuffer, sizeof(readbuffer));
                printf("Received string: %s", readbuffer);
        }
        return(0);

}

fd[0] = Input Seite der Pipe
fd[1] = Output Seite der Pipe