How to get the $_SESSION info with a specific session_id() in PHP?

So far I can only get session info of the current one out of $_SESSION,

how can I investigate开发者_开发百科 the session info of arbitary session_id() ?

session_id() is the answer.

session_id(whateverhereidyouneedhere);
session_start();

If id is specified, it will replace the current session id. session_id() needs to be called before session_start() for that purpose.