On ten skript zase tak tezky nebyl, jeste ho mam schovany:

#!/bin/bash
offbeg=0
while true
do
offend=`expr $offbeg + 511`
nc backup.podrate.cz 9876 > out << NN
GET /backup.tar HTTP/1.1^M
Host: backup.podrate.cz:9876^M
Range: bytes=$offbeg-$offend^M
^M
NN

cat out | sed -e '1,9d' > out.tar
echo -n "BEG=$offbeg END=$offend "
X=`tar tvf out.tar 2>/dev/null | tail -1 `
echo $X
len=`echo $X | awk ' { print $3 } '`
if [ $len -eq 0 ]
then
offbeg=`expr 512 + $offbeg`
else
offbeg=`expr '(' $len - 1 ')' / 512 '*' 512 + 1024 + $offbeg`
fi
done