sample outout will be

0001256457558
001644855855960790
002494850496568568

starting 000,001 and 002 is fixed and rest data is variable and 485585 coming from the input file.

my whole code is below
#!/bin/sh
# write the output file header
function header()
{
rec_typ=000
file_var=00001
fieldid_1=BP
fieldid_2=`date +%y%m%d`
fieldid_3=XXXXXX
flag=P
echo $rec_typ $file_var $fieldid_1$fieldid_2$fieldid_3 $flag > output.txt
}
# append the BPF file with data record and extract the KID information
function transaction1()
{
rec_typ=001
bin_num=$1
account_num=$2
ref_num=
debit_rej_cde=
payment_cde=XXX
adjust_cde=
cre_deb_cde=
pay_curr_cde=
sett_ref_num=
o_sett_ref_num=
o_tran_num=
pay_amount=
card_number=
echo $rec_typ $bin_num $account_num $ref_num $debit_rej_cde $payment_cde $adjust_cde $cre_deb_cde $pay_curr_cde $sett_ref_num $o_sett_ref_num $o_tran_num $pay
_des $pay_amount $card_number >> BPF
}
#append the BPF file with this record
function transaction2()
{
echo="ABC"
}
#append the BPF file with transaction3 record
function transaction3()
{
pay_des=
}
#append the BPF file with trailer record
function trailer ()
{
rec_typ=002
deb_amount=
deb_count=
cre_amount=
cre_count=
}
#if [ -f "OCR.txt"]; then
END=no
while [ $END=no ]
do
exec a1
echo $a1
rectype=`line | cut -c1-2`;
echo "$rectype"
case "$rectype" in
10)
header
echo "inside header"
continue
;;
20)
echo "inside batch header"
continue
;;
30)
BIN=`line | cut -c13-18`;
ACCOUNT=`line | cut -c19-30`;
echo "$ACCOUNT"
transaction1 "$BIN" "$ACCOUNT"
echo "inside transaction1"
continue
;;
31)
transaction2
echo "inside transaction2"
continue
;;
32)
transaction3
echo "inside transaction3"
continue
;;
88)
echo "inside batch trailer"
continue
;;
89)
trailer
echo "inside trailer"
END=yes
exit 0
;;
*)
echo "$rectype"
echo "reeta error in the file"
exit 1 #exit script with error
;;
esac
done < "input.txt"
#read of file
#exit script OK
# fi

may be now you will get better idea what i am trying to do.
code is working file only thing BIN=`line | cut -c13-18`; extracting data from the next line of the input file i want to extarct data from current line of the input file.

thanks in advance.