How can I logout users after a certain period of inactivity (say 20 minutes)?
You are looking for Automated Logout module.
This module provides a site administrator the ability to log users out after a specified time of inactivity. It is highly customizable and includes "site policies" by role to enforce logout.
- Different timeouts based on role
- Disabling of timeouts based on role
- Permission for users to set their own timeout
- Includes some JS mechanisms to keep uses logged in even if multiple tabs are open or if the user is working on a form for a long period of time.
- Includes developer hooks to allow users to remain logged in depending on your own project specific requirements
(or) take a look at Session Limit
A Drupal module to immediately log out (eject) a user whose session has ended
You can change the
session.cookie_lifetime time (in seconds) from the session is created to the cookie expires (when the browser is expected to discard the cookie).
There is a module Session expire which enhances that functionality.