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<TITLE>The Answer Guy 48: Clearing Lilo from MBR</TITLE>
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<H4>"The Linux Gazette...<I>making Linux just a little more fun!</I>"</H4>
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<H4>By James T. Dennis,
<a href="mailto:linux-questions-only@ssc.com">linux-questions-only@ssc.com</a><BR>
LinuxCare,
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<H3 align="left"><img src="../../gx/dennis/qbubble.gif"
height="50" width="60" alt="(?) " border="0"
>Clearing Lilo from MBR</H3>
<p><strong>From Norman Elliott on Thu, 23 Sep 1999
</strong></p>
<P><STRONG>
Just read the item on clearing lilo.
</STRONG></P>
<P><STRONG>
All I do is boot from a Dos ( 5 or greater ) boot disc and issue the
command:
</STRONG></P>
<P><STRONG><BlockQuote><Code>
fdisk <TT>/mbr</TT>
</Code></BlockQuote></STRONG></P>
<P><STRONG>
that seems to fix anything including boot sector viruses.
Maybe Linux fdisk would take the same parameter.
I enjoy your column, keep up the good work,
best wishes,
</STRONG></P>
<P><STRONG>
norm
</STRONG></P>
<BLOCKQUOTE><IMG SRC="../../gx/dennis/bbub.gif" ALT="(!)"
HEIGHT="28" WIDTH="50" BORDER="0"
>
The <TT>/MBR</TT> option was undocumented and only introduced in
MS-DOS 5.0. I don't remember the question to which you
were referring. If I didn't mention FDISK <TT>/MBR</TT> it was
probably because I was not assuming that the user was
trying to restore an MS-DOS 5.0 or later boot loader
to their system.
</BLOCKQUOTE>
<BLOCKQUOTE>
Linux fdisk is a different program and doesn't
touch the boot code in the MBR. It only works on the
partition tables (which comprise the last 66 bytes of the
MBR and possibly a set of others for extended partitions).
</BLOCKQUOTE>
<BLOCKQUOTE>
There are several Linux programs which do write boot
records. <TT>/sbin/lilo</TT> is the most commonly used. 'dd'
will do in a pinch (if you have a .bin image to put into
place).
</BLOCKQUOTE>
<BLOCKQUOTE>
BTW: don't count on <TT>/MBR</TT> to fix a virus. Some viruses
encrypt portions of your filesystem, thus causing major
problems if they aren't removed corectly. To prevent
infection by boot sector viruses, disable the "floppy
boot" options in your BIOS. You should only enable those
long enough to perform an OS installation or system recovery
and disable it immediately thereafter. To prevent viral
infect by "multi-partite" and "file infector" viruses,
stop running MS-DOS. To avoid MS Windows macro viruses,
avoid MS Office, MS Exchange and related software (with
virus^H^H^H^H macroing hooks built into them).
</BLOCKQUOTE>
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<H5 align="center"><a href="http://www.linuxgazette.com/copying.html"
>Copyright ©</a> 1999, James T. Dennis
<BR>Published in <I>The Linux Gazette</I> Issue 48 December 1999</H5>
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