Linux Server Hacks, Volume Two

Hack #31. Edit Your GRUB Configuration with grubby

Save tons of typing (and typos), by using a ready-made tool for editing grub. conf.

A machine that doesn't boot doesn't work. And there are many environments in which the grub.conf file supplied with the distribution just doesn't cut it. Whether you're using kickstart to install a server farm, or just hacking around with new kernel builds on your web server, you can leave your scripting skills on the back burner by making use of grubby, a simple command-line tool that will edit your kernel definitions for you.

Here's an example of a very simple kernel definition from a grub.conf file on a Red Hat Enterprise Linux server:

	title Red Hat Enterprise Linux AS (2.4.21-32.0.1.EL)
			root (hd0,0)
			kernel /vmlinuz-2.4.21-32.0.1.EL ro root=LABEL=/
			initrd /nitrd-2.4.21-32.0.1.EL.img

This is a fairly standard stanza referred to in the GRUB documentation as an "OS definition" (owing to GRUB's ability to boot seemingly any operating system in existence). Occasionally, it becomes necessary to alter the grub.conf file to pass arguments to the kernel at boot time. For example, if you kickstart a server farm and later add serial console connections to the servers, the kernels will not automatically detect the console, and GRUB will not automagically add the arguments necessary to redirect output to the serial terminal device. How to do this is covered in "Use a Serial Console for Centralized Access to Your Systems" [Hack #76] .

This would normally mean ...