NIS configuration

[mod+linux-fai at std.com]

Yah, it's too bad the NIS gets defined if YPDOMAIN is defined.

I had to create a /fai/class/S25nis.source that says:

 #
 # Fix situation where a machine is being setup in an environment
 # that has NIS but where we don't want it defined.
 #
 ifclass NONIS &&  {
     ifclass NIS &&  {
         echo "Both NONIS and NIS are set, so unsetting NIS" >/dev/console
         undefclass NIS
     }
     ifclass YPDOMAIN &&  {
         echo "Both NONIS and YPDOMAIN are set, so unsetting YPDOMAIN" >/dev/console
         undefclass YPDOMAIN
     }
 }


...which employs that undefclass() function mentioned
in my earlier diffs.  This is not necessarily the
right way to do this, but works for me.