Shell Scripting: Expert Recipes for Linux, Bash, and More

Recipe 15-3: Postinstall Scripts

Automated installation using Kickstart is a useful way to programmatically install many similar machines. One thing that is different for every machine is the IP addresses used; Kickstart can configure an IP address during the installation, but cannot configure additional networks or network bonding. This recipe can be fitted into the %post section of a Kickstart file to configure the network to start up with the new values on the next boot.

Technologies Used

• Kickstart
• Configuration of networking under Red Hat Enterprise Linux
• Network bonding
• Functions
• Here documents
• ping

Concepts

Networking is a critical part of computer configuration. If the system is not visible on the network, it does not matter how good everything else on the system is — it is not making its services available. Network bonding is a way to prevent certain common failures from taking the system entirely offline. Using two network adapters for the traffic means that if one fails anywhere along the route, the other can be used instead. It is best to use two different types of network adapter, so that they have different implementations and different kernel drivers. Of course, two different cables are required, and these should go to two separate network switches so that a failure in any of these devices can be tolerated by the system.

Linux has seven different bonding modes, each with its own properties. The mode is specified when the bonding module is loaded into the kernel. ...