Refine rule primitives

The following primitives are specifically assigned to be used in Refine rules:

• confirm_external—Calls a program to run on the cell and supplies all necessary command-line arguments. If the primitive is successful, the event continues to process; if it fails, the event is dropped. For more information about the confirm_external primitive, see confirm_external/2 - run an external program and wait for its termination to continue to process the current event. 
• get_external—Runs an executable on the same computer on which the cell runs and have the executable pass information back to the cell through an interface. For more information about the get_external primitive, see get_external/4 - run an external program and wait for its termination to continue to process the current event by using data retrieved through an interface object.

In addition to the confirm_external and get_external primitives, Refine rules can utilize any primitive that is not assigned to a particular rule type. See Primitives-and-functions-overview for more information about rules and their assigned primitives.