-host command-line option

Specifies a host to connect to. The host must be defined in the current profile. This overrides any auto-connect host specified in the profile.

Note that this is different from specifying a host name or IP address on the command line. The parameter to -host is a name that is looked up in the set of host connections defined in the profile, and the necessary information to make the connection (name or address, port, LU names, host-specific options, etc.) comes from there.

Examples
Connect to the host mainhost. -host mainhost