Red Hat Enterprise Linux 5 Administration Unleashed

82CHAPTER 3Operating System UpdatesClick the create new user link in the upper-right corner of the page to create new users.After a user has been created, click on the username from the list of active users to assignroles and grant users access to systems and system groups.Subscribing to RHN ChannelsWhen a system is registered with RHN, software and hardware information is gathered sothat relevant errata updates can be determined for it. The software information includesthe Red Hat Enterprise Linux release and the system architecture. From this data, thesystem is associated with a base channel such as Red Hat Enterprise Linux (v. 5 for 32-bitx86). Each base channel contains all the latest software, including software updates, forthe release version and architecture. A base channel can have child channels associatedwith it. A child channel contains software that can be installed on any system with the OSrelease and architecture from the base channel.A system can only be associated with one base channel, but it can be subscribed to one ormore child channels. By using the RHN website or YUM, systems can only receive updatesor package installations from channels to which they are subscribed. For example, asystem subscribed to the Red Hat Enterprise Linux (v. 5 for 32-bit x86) base channel canalso be subscribed to the RHEL Virtualization (v. 5 for 32-bit x86) child channel.Channel subscriptions for systems are managed through the RHN website. To subscribe asystem to one or more child channels or change the parent channel, log in to the RHNwebsite at rhn.redhat.com, and select Systems from the horizontal menu. Click on the nameof the system to show a more detailed view of it. Under the Subscribed Channels header,click Alter Channel Subscriptions. All child channels available for subscription are shown.Select which ones to subscribe to, and click Change Subscriptions. To change the parentchannel, select a new channel from the pull-down menu, and click Modify Base Channel.Performing Actions on Individual Systems from theRHN WebsiteTo perform an action on an individual system using the RHN website, log in, and clickSystem on the horizontal menu. From the individual system view, many actions can beperformed including the following:. Update software. Install software. Modify channel subscription. Edit system properties such as entitlement and description. View pending actions for the systemFor example, using the RHN website, an administrator can quickly view a list of updatesfor a specific system registered with RHN and apply one or more of these updates to anindividual system. After selecting Systems from the horizontal menu, another horizontal