From SME Server

YUM'ing and repositories

Command Explanation
yum install <packagename> installs packagename & any package it may need
yum remove <packagename> removes packagename
yum list updates list updates to any installed package
yum list available list available packages in all repos not already installed
grep <reponame> list available packages -shows only from repo name
yum search <packagename> lists all packages in all repos matching packagename
yum clean all --enablerepo=* Is used to clean up various things which accumulate in the yum cache (includes disabled repos)
yum --enablerepo=<reponame> <command> enables a repo not normally enabled
/sbin/e-smith/audittools/newrpms shows all extra packages installed
/sbin/e-smith/audittools/repositories show all repositories and if they are activated or not
db yum_repositories show <reponame> show properties of the repository <reponame> (you may use TAB to auto-complete your command line)