**-^** or just **-**
    Print a short message about the syntax of the command, then exits (**Note**: on Windows just use **-**).
**-+** or just **+**
    Print an extensive usage (help) message, including the explanation of
    any module-specific option (but not the GMT common options), then exits.
**-?** or no arguments
    Print a complete usage (help) message, including the explanation of all options, then exits.
