//
// Written for Computer Networks and Systems lab classes
// AUTHOR : Sergiusz Warga

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


int main() {
	int pipefd[2];
	if (pipe(pipefd) < 0) {
		fprintf(stderr, "Something went wrong!\n");
		return -1;
	}

	pid_t pid;
	pid = fork();

	if (pid == -1) {		// If something went wrong.
		perror("Fork: ");
		exit(EXIT_FAILURE);
	}

	if (pid == 0) {			// If this is a child process.
		dup2(pipefd[1], STDOUT_FILENO);
		execl("/usr/bin/cal", "cal", NULL);
		close(pipefd[1]);
		exit(EXIT_SUCCESS);
	}

	char buff[200] = {};

	while (read(pipefd[0], &buff, sizeof(buff)) > 0) {
		printf("%s", buff);
	}

	int status;
	wait(&status);

	return 0;
}