Yum is installed with centos. This is a short summary for yum. 1. Here is a yum command summary: yum list - List all available packages. yum list installed - List installed packages. yum check-update yum list updates - See if there are updated packages available. yum update - Update all installed packages that have a newer version available. yum install - Install specific packages and their dependencies. yum search - Search all known packages entries (descriptions etc) for word. yum info - Show basic information about a package. yum clean packages - Eliminate any cached packages from the system. 1. Adding other repositories Run this command after startup to obtain the GPG key of the centos mirrors: # rpm --import http://mirror.centos.org/centos/RMP-GPG-KEY-centos4