#include<stdio.h>
#include<unistd.h>
#include<sys/mman.h>
#include<fcntl.h>
#include<ctype.h> 

int main(){
	int fd = open("anewfile", O_RDWR);
	char* our_file = mmap(0, 50, PROT_READ | PROT_WRITE, MAP_SHARED, fd, 0);
	printf("The file starts with %c\n", our_file[0]);
	our_file[0] = 'g';
	for(int i = 0; i < 50; i++)
		our_file[i] = toupper(our_file[i]);
	printf("File contents:  \n%s\n", our_file);

	// This will happen when the process terminates anyway
	munmap(our_file, 50);
	close(fd);
	return 0;	
}