The syntax is: motionbuilder.exe [flags] [Python script | filename].

Startup flags

-console

Opens an output window for the stdout/err stream. Must be used with -verbosePython.

-g [width] [height]

Sets the MotionBuilder window size to the specified values. The default state is maximized.

-S

Starts MotionBuilder in full screen mode. To exit full screen mode, press Alt+Enter.

-suspendMessages

Disables all the warnings and dialogs. This flag is useful for automation purposes when you do not want a script to be interrupted by dialogs. By default, warnings and dialogs are shown.