Folks I performed an install of "java-devel". Several packages got installed. So far so good. Yet, when I performed yum list installed | grep java-devel and also yum rpm -qa | grep java-devel it did not show up as already installed. This behavior appears both on Centos7 and Centos6. This bothers me because as a time-saving effort, I maintain the last output of "yum list installed" and quickly determine whether it's worth running yum. True, yum would "do nothing", but that takes several seconds. Is there some simple explanation? It works for all the other packages I've installed. David