refs:
* red hat yum index:
1. check & update
1.1 check
yum check-update
1.2 update
update one
yum update package_name
update all
yum update
* to update packages automatically: use yum-cron
install: yum install yum-crom
enable auto update: chkconfig yum-cron on; service yum-cron start
status: service yum-cron status
todo
* yum local repo config
* clone a public repo
