Permission denied on codeigniter - php

Question

I'm running an Apache server on my PC with Debian 7 (well, actually Crunchbang, but it's the same thing).
I was playing with the CodeIgniter framework, and it was working all right. I completed the first tutorial, the one in which you create your first static page (this one: http://ellislab.com/codeigniter/user-guide/tutorial/static_pages.html ), and it worked perfectly.
However, as you can see on the very first step, there's a line that goes like this:
[...]
public function view($page = 'home')
[...]
I changed that line to " $page = 'about' ", to try if it could display the other page instead. That's when Hell opened its doors and released the Kraken.
Then it started to show a 404 error, so I changed the settings back again, but the error kept ocurring. I restarted Apache, restarted my PC (I don't know, sometimes it works) and finally, deleted the codeigniter files from my /var/www/ directory, and copied them again.
Now the error is different: It just displays nothing! A blank page, just that. This is what my apache errorlog says:
[Fri Feb 21 23:03:11 2014] [error] [client 127.0.0.1] PHP Warning: require_once(/var/www/system/core/CodeIgniter.php): failed to open stream: Permission denied in /var/www/index.php on line 202
[Fri Feb 21 23:03:11 2014] [error] [client 127.0.0.1] PHP Fatal error: require_once(): Failed opening required '/var/www/system/core/CodeIgniter.php' (include_path='.:/usr/share/php:/usr/share/pear') in /var/www/index.php on line 202

Answer 1

It sounds like the permissions are set incorrectly on your server.
Check what group Apache runs in (I think Debian by default uses www-data), and make sure you set the group owner and read permissions.
# chown www-data:www-data -R /var/www
# chmod g+r -R /var/www
If the above doesn't work, try setting permissions to 777 just to see if the problem lies elsewhere. I couldn't imagine what else could cause that error, though.