php file not included despite setting include_path - php

Question

I have an apache2 server running on my Linux machine. I edited the file /etc/php5/apache2/php.ini by setting include_path to
include_path = ".:/usr/share/php:/var/www/subdir"
To make sure I did not change the wrong file, I also edited all other php.ini files (there was one more) I found on my computer and checked the output of phpinfo() which printed the correct include_path from above. (I also restarted apache2.)
However, when I use lines like
use some\name\space;
require_once('./subsubdir/file.php');
in a file start.php (which lies in another directory /var/www/subdir/anothersubdir/), the require_once command does not work, as I get the following error in the apache log file
[error] [client 127.0.0.1] PHP Fatal error: require_once(): Failed opening required './subsubdir/file.php' (include_path='.:/usr/share/php:/var/www/subdir') in /var/www/subdir/anothersubdir/start.php on line x
I also tried
require_once('/subsubdir/file.php');
but it did not work. How do I have to inlcude file.php when I have set the include_path as shown above ?
Thanks a lot in advance !

Answer 1

The first questions I would be asking myself are:
is the webserver running in a chroot environment?
what are the permissions on the target file?
And a simple way to answer both of these would be:
print getcwd() . "<hr />\n";
$t='/var/www/subdir/anothersubdir/subsubdir/file.php';
function show_permissions($path)
{
if (strlen($path)>1) {
show_permissions(dirname($path));
}
if (is_readable($path)) {
print "Permissions for $path: " . var_export(stat($path)) . "<br />";
} else {
print "can't read $path <br /> \n";
}
}
(my money would be on a permissions problem - not a path issue)

Answer 2

Try rebooting Apache, to clear the internal cache.