keystone restart error

opnstack@ubuntu:~/devstack$ keystone restart
usage: keystone [--version] [--debug] [--os-username <auth-user-name>]
                [--os-password <auth-password>]
                [--os-tenant-name <auth-tenant-name>]
                [--os-tenant-id <tenant-id>] [--os-auth-url <auth-url>]
                [--os-region-name <region-name>]
                [--os-identity-api-version <identity-api-version>]
                [--os-token <service-token>]
                [--os-endpoint <service-endpoint>] [--os-cache]
                [--force-new-token] [--stale-duration <seconds>] [--insecure]
                [--os-cacert <ca-certificate>] [--os-cert <certificate>]
                [--os-key <key>] [--timeout <seconds>]
                <subcommand> ...
keystone: error: argument <subcommand>: invalid choice: 'restart' (choose from 'catalog', 'ec2-credentials-create', 'ec2-credentials-delete', 'ec2-credentials-get', 'ec2-credentials-list', 'endpoint-create', 'endpoint-delete', 'endpoint-get', 'endpoint-list', 'password-update', 'role-create', 'role-delete', 'role-get', 'role-list', 'service-create', 'service-delete', 'service-get', 'service-list', 'tenant-create', 'tenant-delete', 'tenant-get', 'tenant-list', 'tenant-update', 'token-get', 'user-create', 'user-delete', 'user-get', 'user-list', 'user-password-update', 'user-role-add', 'user-role-list', 'user-role-remove', 'user-update', 'discover', 'bootstrap', 'bash-completion', 'help', 'bash_completion')
opnstack@ubuntu:~/devstack$