phpsession失效

一个基于thinkphp的项目，session设置无效
在a.php页面设置完session之后，可以打印出session的值，但是刷新之后就又没了
在服务器新建一个可以访问的php文件

<?php
error_reporting(E_ALL);
ini_set('display_errors', '1');
session_start();
session_register('A');
$_SESSION['A'] = 10;
echo $_SESSION['A'];
?>

访问，报如下错误，

Warning: session_start(): open(/var/lib/php/session/sess_veiso2o3bco5do2mlkvhi18jq5, O_RDWR) failed: Permission denied (13) in /home/xxx.com/public_html/test1.php on line 4 Deprecated: Function session_register() is deprecated in /home/xxx.com/public_html/test1.php on line 5 10 Warning: Unknown: open(/var/lib/php/session/sess_veiso2o3bco5do2mlkvhi18jq5, O_RDWR) failed: Permission denied (13) in Unknown on line 0 Warning: Unknown: Failed to write session data (files). Please verify that the current setting of session.save_path is correct (/var/lib/php/session) in Unknown on line 0

修改session的目录为程序有权限操作的目录即可
修改thinkphp入口文件,在定义 APP_PATH 的代码下加上

session_save_path(APP_PATH . 'Runtime/session/');