Working with externals question

[Bojsza]

I have been working on an external for the Linux platform. A very basic 
one works (includes a function and a command).
But I am having problems with the external which I have taken from some 
open source code. The code normally runs from the command line with 
several switch options such as

trigger -F test.cfg -r data.04

This should return several lines of data. Currently I get a script 
error usually referring to the switches (not trigger itself -- so I 
think that part of the external is working)

Should I be setting this as a command or a function in the external?
Is there a particular format I should use for passing the parameters?
Is the a way to tell if the external knows the existence of the 
function or command?

The external that I have working is the basic one that I can ask the 
user to input a number and the external adds 1 to it and returns the 
result. Similarly another example is where a user is asked for two 
numbers and the product is returned.

Any guidance is appreciated.

regards,

Glen