Red Hat ENTERPRISE LINUX 5 - VIRTUAL SERVER ADMINISTRATION, Installation Manual

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Chapter 27. Basic System Recovery
280
•
rpm
for installing or upgrading software
•
joe
for editing configuration files
Note
If you try to start other popular editors such as
emacs
,
pico
, or
vi
, the
joe
editor is
started.
27.2.1. Reinstalling the Boot Loader
In many cases, the GRUB boot loader can mistakenly be deleted, corrupted, or replaced by other
operating systems.
The following steps detail the process on how GRUB is reinstalled on the master boot record:
• Boot the system from an installation boot medium.
• Type
linux rescue
at the installation boot prompt to enter the rescue environment.
• Type
chroot /mnt/sysimage
to mount the root partition.
• Type
/sbin/grub-install bootpart
to reinstall the GRUB boot loader, where
bootpart
is
the boot partition (typically, /dev/sda).
• Review the
/boot/grub/grub.conf
file, as additional entries may be needed for GRUB to
control additional operating systems.
• Reboot the system.
27.3. Booting into Single-User Mode
One of the advantages of single-user mode is that you do not need a boot CD-ROM; however, it does
not give you the option to mount the file systems as read-only or not mount them at all.
If your system boots, but does not allow you to log in when it has completed booting, try single-user
mode.
In single-user mode, your computer boots to runlevel 1. Your local file systems are mounted, but
your network is not activated. You have a usable system maintenance shell. Unlike rescue mode,
single-user mode automatically tries to mount your file system.
Do not use single-user mode if your
file system cannot be mounted successfully.
You cannot use single-user mode if the runlevel 1
configuration on your system is corrupted.
On an x86 system using GRUB, use the following steps to boot into single-user mode:
1. At the GRUB splash screen at boot time, press any key to enter the GRUB interactive menu.
2. Select
Red Hat Enterprise Linux
with the version of the kernel that you wish to boot and type
a
to
append the line.
3. Go to the end of the line and type
single
as a separate word (press the
Spacebar
and then
type
single
). Press
Enter
to exit edit mode.