What is the default shell for accessing clustered ONTAP?

SPshell is the shell of the Service Processor, used for out-of-band hardware management, not the default CLI for ONTAP cluster administration.

Nodeshell provides access to node-scoped, 7-Mode style commands and must be entered explicitly with the 'system node run' command from within Clustershell.

Clustershell is the default interactive shell presented when an administrator logs into a clustered ONTAP system via SSH or the console. It provides cluster-wide commands and is the primary management interface. The other shells must be explicitly entered from within Clustershell.

Systemshell is a low-level diagnostic UNIX shell used only for advanced troubleshooting and requires special activation, making it not the default login shell.