Red Hat ENTERPRISE LINUX 3 Reference Manual

Also see for ENTERPRISE LINUX 3 - SECURITY GUIDE: Tuning guide Installation guide Installation guide Installation guide Manual

Contents

Chapter 2. Boot Loaders 15The following shows the chainloader command with a similar blocklist designation at the GRUBcommand line after setting the correct device and partition as root:chainloader +12.4.3. The Root File System and GRUBThe use of the term root file system has a different meaning in regard to GRUB. It is important toremember that GRUB’s root file system has nothing to do with the Linux root file system.The GRUB root file system is the top level of the specified device. For example, the image file(hd0,0)/grub/splash.xpm.gz is located within the /grub/ directory at the top-level (or root)of the (hd0,0) partition (which is actually the /boot/ partition for the system).Once GRUB has loaded its root partition (which equates to the /boot partition and contains the Linuxkernel), the kernel command can be executed with the location of the kernel file as an option. Oncethe Linux kernel boots, it sets up the root file system that Linux users are familiar with. The originalGRUB root file system and its mounts are forgotten; they only existed to boot the kernel file.Refer to the root and kernel commands in Section 2.6 GRUB Commands for more information.2.5. GRUB InterfacesGRUB features three interfaces which provide different levels of functionality. Each of these interfacesallows users to boot the Linux kernel or another operating system.The interfaces are as follows:Menu InterfaceThis is the default interface shown when GRUB is configured by the installation program, thisis the interface shown by default. A menu of operating systems or kernels preconfigured aredisplayed as a list, ordered by name. Use the arrow keys to select an option other than the defaultselection and press the [Enter] key to boot it. Alternatively, a timeout period is set, after whichGRUB loads the default option.Press the [e] key to enter the entry editor interface or the [c] key to load a command line interface.Refer to Section 2.7 GRUB Menu Configuration File for more information on configuring thisinterface.Menu Entry Editor InterfaceTo access the menu entry editor, press the [e] key from the boot loader menu. The GRUB com-mands for that entry are displayed here, and users may alter these command lines before bootingthe operating system by adding a command line ([o] inserts a new line after the current line and[O] inserts a new line before it), editing one ([e]), or deleting one ([d]).After all changes are made, the [b] key executes the commands and boots the operating system.The [Esc] key discards any changes and reloads the standard menu interface. The [c] key loadsthe command line interface.TipFor information about changing runlevels with GRUB using the menu entry editor, refer to Sec-tion 2.10 Changing Runlevels at Boot Time.