By default, WP-CLI executes every command as a logged-out, unauthenticated user.
$ wp eval 'echo get_current_user_id();' 0
To execute a command as an existing WordPress user, you can use the
--user=<user> global parameter, which accepts a user id, login, or email address:
$ wp eval 'echo get_current_user_id();' --user=runcommand 1
It’s worth noting WP-CLI’s user handling is relatively special; even though commands are executed as a logged-out user by default, you can perform many operations that typically require authentication and authorization in the WordPress dashboard.