Installation guide

62 Chapter 3. Rescue Mode

5. Back at the GRUB screen, type b to boot into single user mode.

If you are using LILO, specify one of these options at the LILO boot prompt (if you are using

the graphical LILO, you must press [Ctrl]-[x] to exit the graphical screen and go to the boot:

prompt):

boot: linux single

boot: linux emergency

In single-user mode, you computer boots to runlevel 1. Your local ﬁlesystems will

be mounted, but your network will not be activated. You will have a usable system

maintenance shell.

In emergency mode, you are booted into the most minimal environment possible. The root

ﬁlesystem will be mounted read-only and almost nothing will be set up. The main advan-

tage of emergency mode over linux single is that your init ﬁles are not loaded. If init is

corrupted or not working, you can still mount ﬁlesystems to recover data that could be lost

during a re-installation.

Have you ever rebuilt a kernel and, eager to try out your new handiwork, rebooted before

running /sbin/lilo? If you did not have an entry for an older kernel in lilo.conf, you

had a problem. If you would like to know a solution to this problem, read this section.

In many cases, you can boot your Red Hat Linux system from the Red Hat Linux boot disk

with your root ﬁlesystem mounted and ready to go. Here is how to do it:

Enter the following command at the boot disk’s boot: prompt:

linux single root=/dev/hdXX initrd=

Replace the XX in /dev/hdXX with the appropriate letter and number for your root partition.

What does this command do? First, it starts the boot process in single-user mode, with

the root partition set to your root partition. The empty initrd speciﬁcation bypasses the

installation-related image on the boot disk, which will cause you to enter single-user mode

immediately.

Is there a negative side to using this technique? Unfortunately, yes. Because the kernel on

the Red Hat Linux boot disk only has support for IDE built-in, if your system is SCSI-based,

you will not be able to do this. In that case, you will have to access rescue mode using the

linux rescue command mentioned above.

1. To create an installation boot diskette, insert a blank ﬂoppy disk and use the images/boot.img ﬁle

on the Red Hat Linux CD-ROM #1 with the command dd if=boot.img of=/dev/fd0.