pipe1.c

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

int main() {
  pid_t pid;
  int fd[2];

  // initialize pipe that will be used
  // to send data from the child process
  // to the parent process
  pipe(fd);

  switch ((pid = fork())) {
    case -1:
      // error occurred
      printf("Error using fork()");
      break;
    case 0:
      // close reading side of pipe in child process
      close(fd[0]);

      // write message to pipe
      char message[] = "Hello there!";
      write(fd[1], message, strlen(message));
      break;
    default:
      // close writing side of pipe in parent process
      close(fd[1]);

      // read message to buffer
      char buffer[100];
      read(fd[0], buffer, PIPE_BUF);

      // print out message
      printf("Got message: %s\n", buffer);
  }

  return EXIT_SUCCESS;
}