split files with dd

split.sh

#!/bin/sh

if [ $# -ne 2 ]
then
	echo "./split.sh <number of files> <filename>"
	exit 
fi

size=`du $2 | awk '{ print $1 }'`
parts=`expr $size \/ $1`
parts=$[$parts+1] # "truncate" 
echo $parts
echo $size
n="0"
i="1"

# split 
while [ `expr $n + $parts` -lt $size ] 
do
	dd if=$2 of=pt-$i skip=$n bs=1K count=$parts
	n=`expr $n + $parts`
	i=$[$i+1] 
done
dd if=$2 of=pt-$i skip=$n bs=1K

# merge

cp pt-1 out

n="0"
i=$[$i-1] 
for ii in `seq 2 $i`
do
	n=`expr $n + $parts`
	dd if=pt-$ii of=out bs=1K seek=$n count=$parts
done
n=`expr $n + $parts`
i=$[$i+1] 
dd if=pt-$i of=out bs=1K seek=$n

# verify the integrity

md5sum $2 out