create ISO file

Edwin Davidson <[email protected]> Mon, 29 Jun 2015 11:47:02 -0300 (ADT)

Newsgroups	gmane.comp.video.dvdrip.user
Message-ID	<[email protected]>

Hello,

I used dvdrip to extract the 5 parts to the table of contents of a dvd. 
This created 5 directories with various .vob files.  my question today is 
- how can I use dvdrip to create an .iso image file with these .vob files. 
dvdrip did not create an .avi file either.  am using ubuntu 15.04.

Thank you.
Edwin