RHEL Yum

Yum Repo Management

By default, Redhat repo does not contain php-mbstring in Amazon AWS. php-mbstring is required for phpMyAdmin, wordpress, etc.
To Install php-mbstring

yum repolist all
# found rhui-REGION-rhel-server-optional in the list
yum-config-manager --enable rhui-REGION-rhel-server-extras rhui-REGION-rhel-server-optional
yum search php-
yum install php-mbstring

Yum Add or Disable Repo

Add Repo

yum-config-manager --add-repo repository_url

Disable Repo

rpm -qa |grep -i rpmfusion
$rpmfusion-nonfree-release-13-2.noarch
$rpmfusion-free-release-13-2.noarch
#Then do
rpm -e <reponame>
#example
rpm -e rpmfusion-free-release-13-2.noarch

see also http://www.if-not-true-then-false.com/2010/yum-remove-repo-repository-yum-disable-repo-repository/

Check RHEL version

$ cat /etc/redhat-release 
CentOS release 5.4 (Final)