Recovering from Fatal Disasters
*******************************

You can use the MCC boot floppy to recover from fatal disasters.
What kind of disaster requires such measures?  Sometimes people
accidentally do things which make the system unbootable.  For example,
they may edit or delete one of the configuration files in `/etc', or
they may delete a fundamental utility, like `/etc/init' or one of the
shared libraries in `/lib'.

In many of these cases, the system will still boot in single user
mode.  To do this you must have installed LILO as your boot loader, even
if it is installed in a file system partition and is called by another
boot loader, such as the DOS or OS/2 loaders.  When LILO boots, you must
force it to prompt you.  No special action is necessary if you put the
`prompt' command instead of the `delay' command in `/etc/lilo/config';
this forces a prompt in all cases.

To force LILO to prompt, you must perform one of the following
actions:

   - Hold the `SHIFT' key down at boot time.

   - Hold the `CTRL' key down at boot time.

   - Hold the `ALT' key down at boot time.

   - Set the `CAPS LOCK' key on at boot time.

   - Set the `SCROLL LOCK' key on at boot time.

When the prompt `boot:' appears, you must type the name of your
default kernel followed by the word `single'; for example,

     boot: linux single

If you don't remember the name of your kernel, press the `TAB' key.
This causes a list of the available options to be displayed.

In very serious cases, when you cannot boot in single user mode, you
may use the MCC boot floppy to recover.  Simply boot from the floppy in
read-only mode, pressing `<RETURN>' at the LILO prompt.  If the file
`/bin/sh' is intact on your hard disk, you can choose `e' from the
menu, and this will start a shell after mounting the various
partitions.  At this point, most of the editors and other utilities
should work correctly.  The commands `mount' and `umount' do not work
at all.  Repair the damage, then reboot the system.  Do not use `halt',
`reboot', or `shutdown' to reboot; type `CTRL-D' or `exit'.

In the very worst possible case, for example when `/bin/sh' has been
deleted, you can re-install Linux from the boot floppy.  As with all MCC
upgrades, this creates a special directory named `/backupdirs', in
which your existing configuration files are saved; for example,
`/etc/passwd' is moved to `/backupdirs/etc/passwd'.  It is not possible
-- or desirable -- to leave such files if they exist, since the newly
installed system might not boot.  The file `/etc/syslogd' is also moved
to the `/backupdirs' directory when you install the Base package from
the boot floppy.  You will need to run LILO again before rebooting.  Use
the command

     ROOT=/root;/etc/lilo/lilo

If you recompile your kernel, or if you use one of the smaller MCC
kernels, you may wish to customise the MCC boot floppy.  Assuming that
you have your kernel in `/etc/Image' and the matching data file
`/etc/psdatabase', mount a `standard' MCC boot floppy in write mode
from drive 0 on `/mnt'.  Then give these commands:

     cp -p /etc/Image /mnt/etc/Image
     tar cf - /etc/psdatabase|gzip -9 >/mnt/psdata.tgz
     /etc/lilo/lilo -C /mnt/etc/config.lilo
     umount /mnt

This should produce a recovery system that will boot your own kernel
(so that the `ps' commands all work) and reinstall your own kernel if
you install Linux from the floppy.
