PHP session not being saved between pages

I've just bought some new server space and am migrating a very simple PHP app to it that works fine on my other server.

For some reason the session data is not being stored in the $_SESSION variable between pages on the new server. I have looked at this similar SO article and many others to try and fix the issue.

I can confirm that:

1. The session stuff is working fine on my other site. I have looked into the directory defined by session.save_path and there are loads of session files in there (on the OLD server).
2. I have echoed the contents of the $_SESSION variable at the end of a page, and it is holding the correct data, it's just not being saved.
3. I have echo'd session_id() for every page and get the same output.
4. I have had a look in the folder specified by the NEW server's session.save_path folder (/usr/lib/php/session) and there aren't any files in there. I have checked the permissions and it's set at drwxrwx---, which should mean that the php program can write to it, right?
5. I have no .htaccess file.
6. I am running CentOS 5.5

This is from the relevant part of开发者_开发问答 the phpinfo() output:

Session Support     enabled
Registered save handlers    files user
Registered serializer handlers  php php_binary wddx

Directive   Local Value Master Value
session.auto_start  Off Off
session.bug_compat_42   Off Off
session.bug_compat_warn On  On
session.cache_expire    180 180
session.cache_limiter   nocache nocache
session.cookie_domain   no value    no value
session.cookie_lifetime 0   0
session.cookie_path /   /
session.cookie_secure   Off Off
session.entropy_file    no value    no value
session.entropy_length  0   0
session.gc_divisor  1000    1000
session.gc_maxlifetime  1440    1440
session.gc_probability  1   1
session.hash_bits_per_character 5   5
session.hash_function   0   0
session.name    PHPSESSID   PHPSESSID
session.referer_check   no value    no value
session.save_handler    files   files
session.save_path   /var/lib/php/session    /var/lib/php/session
session.serialize_handler   php php
session.use_cookies On  On
session.use_only_cookies    Off Off
session.use_trans_sid   0   0

I've contacted the hosting company and they won't look into it because they say it's a software issue and it's not a managed account. Grrrrr...

Just so you can see some code that isn't working, I have stolen code from the article I have linked to:

// info.php
<?
session_start();

$_SESSION['ID'] = "112233";
$_SESSION['token'] = "mytoken";

print $_SESSION['ID'];
print $_SESSION['token'];
?>
<a href="info2.php">info 2</a>

and one called info2 with this code:

// info2.php
<?
session_start();

print $_SESSION['ID'];
print $_SESSION['token'];
?>
<a href="info.php">info</a>

result is printing the array data in info.php, but no output in info2.php (apart from the link of course).

Many thanks in advance for any help.

Try explicitly closing the session before the script ends; maybe you see some error message then.

<?php
error_reporting(E_ALL); ini_set('display_errors', true);
session_start();
echo '<a href="?', time(), '">refresh</a>', "\n";

echo '<pre>';
echo 'session id: ', session_id(), "\n";

$sessionfile = ini_get('session.save_path') . '/' . 'sess_'.session_id();
echo 'session file: ', $sessionfile, ' ';
if ( file_exists($sessionfile) ) {
    echo 'size: ', filesize($sessionfile), "\n";
    echo '# ', file_get_contents($sessionfile), ' #';
}
else {
    echo ' does not exist';
}

var_dump($_SESSION);
echo "</pre>\n";

$_SESSION['ID'] = "112233";
$_SESSION['token'] = "mytoken";

session_write_close();
echo 'done.';

If your session file has zero size, make sure there is still disk space available on your server. That was the problem I had.

Check disk space with df -h on a linux server.