Luna/apps/app.c

#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <sys/stat.h>
#include <time.h>
#include <unistd.h>

void bye()
{
    printf("byeee!\n");
}

int main()
{
    atexit(bye);
    printf("Welcome to %s from userspace (pid %d)!\n", "Luna", getpid());

    mkdir("/home", 0);
    mkdir("/home/user", 0);

    int fd = open("/home/user/notes.txt", O_RDWR | O_CREAT);
    if (fd < 0)
    {
        perror("open");
        return 1;
    }

    char buffer[512];
    ssize_t nread = read(fd, buffer, sizeof(buffer));
    buffer[nread] = 0;

    printf("/home/user/notes.txt says: %s", buffer);

    close(fd);

    time_t now = time(NULL);
    printf("date: %s", ctime(&now));
}