id
- If id is specified, it will replace the current session id. session_id() needs to be called before session_start() for that purpose. Depending on the session handler, not all characters are allowed within the session id. For example, the file session handler only allows characters in the range a-z, A-Z and 0-9!
Замечание: When using session cookies, specifying an id for session_id() will always send a new cookie when session_start() is called, regardless if the current session id is identical to the one being set.