Thanks, that's been a useful starting point and it's good to know that you can indeed do it.

However, I found the help pages weren't great for explaining the format of the commands to use.  I tried various formats I came across, like the ones for Windows Command Line (the Run prompt), but those didn't seem to work.  I basically need a command to launch the programme qHull, and a command to enter a line into that programme and run it.

Any further direction as to the command format needed greatly appreciated!  Thanks.

Thanks, that's great!  Works like a charm, at least when I get the file names right...!  In fact, I think I can use some of that coding to ease the human input even further.  Cheers again!