php session related question

Session Functions:

session_cache_expire -- Return current cache expire

session_cache_limiter -- Get and/or set the current cache limiter

session_commit -- Alias of session_write_close()

session_decode -- Decodes session data from a string

session_destroy -- Destroys all data registered to a session

session_encode -- Encodes the current session data as a string

session_get_cookie_params -- Get the session cookie parameters

session_id -- Get and/or set the current session id

session_is_registered -- Find out whether a global variable is registered in a session

session_module_name -- Get and/or set the current session module

session_name -- Get and/or set the current session name

session_regenerate_id -- Update the current session id with a newly generated one

session_register -- Register one or more global variables with the current session

session_save_path -- Get and/or set the current session save path

session_set_cookie_params -- Set the session cookie parameters

session_set_save_handler -- Sets user-level session storage functions

session_start -- Initialize session data

session_unregister -- Unregister a global variable from the current session

session_unset -- Free all session variables

session_write_close -- Write session data and end session