session.save_handler = redis
session.save_path = "tcp://127.0.0.1:6379?auth=youpwd"
session.gc_maxlifetime = 21600

ini_set("session.save_handler", "redis");
ini_set("session.save_path", "tcp://127.0.0.1:6379?auth=youpwd");
ini_set("session.gc_maxlifetime", '21600');

<?php
// 如果未修改php.ini下面两行注释去掉
ini_set('session.save_handler', 'redis');
ini_set('session.save_path', 'tcp://127.0.0.1:6379');
 
session_start();
$_SESSION['sessionid'] = 'this is session content!';
echo $_SESSION['sessionid'];
echo '<br/>';
 
$redis = new redis();
$redis->connect('127.0.0.1', 6379);
 
// redis 用 session_id 作为 key 并且是以 string 的形式存储
echo $redis->get('PHPREDIS_SESSION:' . session_id());