shell command callback question

[Josh Mellicker]

When you execute a shell command in Terminal in OS X, (in appropriate  
cases) you get text back as the command executes. For example, when  
searching a hard drive, even though the entire process takes a while,  
at each moment it finds a matching file, it echoes it to the terminal,  
so you get a little feedback while you're waiting.

However, in Revolution, when I execute a shell command, nothing is  
returned until the entire command is finishing executing, at which  
point I get all the echoed text at once.

I am brand new at this and probably missing something obvious... how  
do you set up a callback so you get the echoed text in "real time"?