session_create_id is used to create new session id for the current session. It returns collision free session id.
If session is not active, collision check is omitted.
Session ID is created according to php.ini settings.
It is important to use the same user ID of your web server for GC task script. Otherwise, you may have permission problems especially with files save handler.
If prefix is specified, new session id is prefixed by prefix. Not all characters are allowed within the session id. Characters in the range a-z A-Z 0-9 , (comma) and - (minus) are allowed.
session_create_id returns new collision free session id for the current session. If it is used without active session, it omits collision check. On failure, false is returned.