Problem

-- In 7.3.1, you see this when running managedomain -

Running in command interpreter mode. Enter 'quit' or 'q' to exit.
Enter 'help' to view help topics. Enter 'help topic' to view help for a topic.
Press TAB to view and complete commands.

Resolution

* This is the new command interpreter mode which was added because the list of available options is constantly growing.  As the prompt above says, you can type 'help' to see a list of available commands and it will give you this output -

> help

Main Commands
=============
add                       delete_host       initialize        sign_csr
add_service_only          delete_instance   list_deployments  submit_cert
add_tag                   delete_tag        print_topology    topology_check
change_domain_passphrase  deploy            q                 topology_compare
change_passphrase         download_archive  quit              topology_merge
create_archive            edit_group        regen_certs       topology_synch
create_instance           edit_host         remove_service
delete_group              edit_instance     reset

Help Topics
===========
menu  ssl

Other Commands
==============
help

Further help for is available by typing help <command> at the prompt, e.g. help add.  The old menu-style managedomain is still available in 7.3.1 if you run managedomain --menu