Checking if session cookies have been created

Session name is the name of the cookie used to store sessions. You can use this to detect if cookies for a session have been created for the user:

if(isset($_COOKIE[session_name()])) {
    session_start();
}

Note that this method is generally not useful unless you really don’t want to create cookies unnecessarily.

Changing session name

You can update the session name by calling session_name().

//Set the session name
session_name('newname');
//Start the session
session_start();

If no argument is provided into session_name() then the current session name is returned.

It should contain only alphanumeric characters; it should be short and descriptive (i.e. for users with enabled cookie warnings). The session name can’t consist of digits only, at least one letter must be present. Otherwise a new session id is generated every time.