part 2 for https://mause.me/blog/2012/11/04/linux-security-and-permissions.html

permissions.c

int main() {
    system("chown www-data:www-data /var/www/docs;");
    system("chmod go+rx -R /var/www/docs");
    system("chmod go+rw -R /var/www/builds");
    return 0;
}