#!/bin/sh

IMG=$1

if ! [ $# -eq 1 ]; then
	echo "usage $0 <img_file_name>"
	exit 1
fi


if ! [ -f $IMG ]; then
	echo $IMG does not exist 
	exit 1
fi	
ls -als $IMG
mount -o loop $IMG mnt || exit 1
INSTALLDIR=`pwd`/mnt/
yum clean packages --installroot=$INSTALLDIR 
dd if=/dev/zero of=mnt/fillme bs=1M
sync
rm mnt/fillme
umount mnt
cp --sparse=always $IMG $IMG.new
mv  $IMG.new $IMG
ls -als $IMG

