No rule to make target errors seen when installing the RealPort driver in Linux

The following errors are seen when attempting to install the RealPort driver in Linux:

make[2]: Entering directory `/usr/src/dgrp-1.9/dinc'
make[2]: *** No rule to make target `dinc.o', needed by `dinc'.  Stop.

This is typically seen if the user is not logged in with the root environment variables.  If using su to switch user, be sure and add the hyphen (-) for the environment:

$  su -