[CentOS] Centos Gotcha: YUM Groupinstall

Folks

I have encountered a situation with YUM that isn't what I expected.

Let's suppose I want to install a group, call it G.  My first 
question would be -- is the group already installed.  Realize all of 
this is scripted.

So, I use
   yum groupinfo
and I see the list of installed groups, and those not yet installed.

If group G is in the list of installed groups, one would think that 
there's no point in issuing a "groupinstall".

But, to my surprise, a group can be listed as "installed", only to 
find that a groupinstall will actually do a lot of installs.

So, I had to adapt my script to perform a "groupinfo G", parse the 
modules, and individually test them to see if they need installation.

I do not understand this behavior -- group G is shown as "installed", 
but it really isn't.

David Kurn