delete boot code from MBR

delete-mbr-bootcode.sh

#!/bin/sh

if [ -z "$1" ] || [ ! -e $1 ] ; then
    echo " !! Device '$1' not found" >&2
    exit 1
fi

TMPFILE=`mktemp /tmp/mbr.XXXXXXXX`

if [ ! -e $TMPFILE ] ; then
    echo " !! Unable to create temp file" >&2
    exit 1
fi

sysctl kern.geom.debugflags=0x10

dd if=$1 of=$TMPFILE bs=512 count=1 > /dev/null 2>&1
echo -n "current MBR checksum is " && md5 -q -- $TMPFILE

dd if=/dev/zero of=$TMPFILE bs=1 count=446 conv=notrunc > /dev/null 2>&1
echo -n "new MBR checksum is " && md5 -q -- $TMPFILE

dd if=$TMPFILE of=/dev/ad0 > /dev/null 2>&1
echo "new MBR written"

rm $TMPFILE