#!/bin/bash

if [ $# -ne 2 ]
then
	echo "$0 [filename] [size in kb]"
	exit 1
fi

filename=$1
size=$2
i=0

while [ $i -lt $size ]
do
	i=`expr $i + 7`
	echo -n "$i" | dd of=$1 bs=1024 seek=$i
done