Q: In your "RPG IV Modules, Procedures & Service Programs" presentation, there is an example showing how to use QCMDEXC in a prototype. If an error occurred while executing this code is there a way to handle it internally?

A: Here's an example of catching an error in this scenario...

D Gocmd           PR                  Extpgm('QCMDEXC')
D                            3000    Const Options(*Varsize)
D                               15  5 Const
D Cmd             S           3000    Varying
 /Free
  Monitor;
    Cmd = 'BAD COMMAND';
    Gocmd(Cmd:%Len(Cmd));
  On-error;
    Dsply %Status;
     // Status = 0202 Command failed
  Endmon;
 /End-free

You could also use the (e) extender on the CALLP to Gocmd, instead of using Monitor.

If you wanted to catch a more specific error, positions 40-46 of the program status data structure holds the error message identifier:

D                SDSD Errmsgid                  40  46

Or, you could to receive a message from the command, maybe using an API in a wrapper procedure.