yum

Error: pkgKey  doesn't exist in repo base (centos5.x)


 yum clean all ; yum clean metadata ; yum -y update

###

The program package-cleanup is found in the yum-utils package.


yum install yum-utils
yum-complete-transaction --cleanup-only
package-cleanup --dupes ; package-cleanup --problems


###Proxy

vi  /etc/yum.conf 
proxy=http://proxy_ip:port

http://wiki.debian.org.hk/w/Manage_software_with_YUM