title: Yum and RPM show that the number of installed packages is different
body: <pre><code>[root@study ~]# rpm -qa | wc -l
  777
  
  [root@study ~]# yum list installed | wc -l
  1054
  </code></pre>
  
  <p>i want to know why different,shoud i get correct number of installed packages?</p>