What is $interim_login?

Question

I found an $interim_login variable within the wp-login.php file, and I'm not sure what it does or what it is. The documentation around the interwebs is pretty sparse.

What is $interim_login?

Answer 1

The variable $interim_login is TRUE when the log-in session of a user expires while she is working in the back end, for example during an auto-save action. In this case a message asking to log in again appears at the bottom of the editor:

The same can happen in the theme customizer.

The $_REQUEST variable that switches the log-in form to interim is interim-login. Note how the underscore is replaced with a dash for no obvious reason.

Answer 2

Basically $interim_login tells WordPress that the users session has expired, prompts the user to log back in and takes them back to the page they were on when the session expired.

So for example if the user is sitting in the dashboard all day and then gets back on and tries to edit something but their session expired and they are no longer logged in WordPress will call 'interim-login' and allow the user to log back in and continue editing where they left off.

You can study how interim-login works by checking out.

wp-admin\customize.php line: 158

wp-admin\includes\ajax-actions.php line: 1048

and of course in

wordpress\wp-login.php