Possible Duplicate:
How do I expire a PHP session after 30 minutes?
I am destroying all session var in logout.php and calling it when user click on logout, what is user does not click on logout.php but directly close the browser. how can i delete session then???
You can't detect when a user closes the browser or types in a new address. You basically need to have a "timeout" facility like the rest of the websites have.
You could set a cron job on the server to check for stale sessions But this is not a great solution since you have to deploy another solution (cron job) with your project. The way I would do it is have a check_credentials.php file included in your project that runs right after your DB connection, you will then add two fields in your users table for your projects users called: session_id AND last_checkin. The process will work like so:
Login:
Then you can have all the users do stale session checks at every page request:
Page Query:
You can modify another users session (see below), although personally, I would recommend against it. As I imagine it can open up a whole world of session hijacking and other vulnerabilities.
With your example use case
A common user is logged, while in the same time an administrator uses the Admin functions and change some value for this user. If the value is not something obtained from the database every time, the session variable for that current logged in user need to have its value changed.
You would be better of updating the value in the database and then just checking to see if it's changed before you process the next page. If you don't want to be checking multiple user fields before each page load then when you update the user in the admin panel, you can build a hash of the values and add it to a new column called session_hash. Then just compare this field on page load
But if you still want to modify another user's session, you can set your current session_id to the targets.
// End my current session and save its id
session_start();
$my_session_id = session_id();
session_write_close();
// Modify our target session
session_id($target_id);
session_start();
$_SESSION['is_logged_in'] = false;
session_write_close();
// Start our old session again
session_id($my_session_id);
session_start();
EDIT
Example: https://www.samdjames.uk/session_example/index.php
Example Src: https://gist.github.com/SamJUK/c220e3742487567c6262238edf85695e
Instead of setting the time in ini to a fixed length, remind that session timeout is reset on reload. So create some ajax code that does a request every 5 minutes or so to a file (image or smth). This way the timer is reset every 5 minutes and users can spend a day filling out your forms.
You can set an expiration time for the session data, test it with each
session_startcall and destroy the session if it’s expired: