#!/bin/sh
sed -n '/[0-9][0-9]\/[0-9][0-9]\/[0-9][0-9][0-9][0-9]/p' time.txt | sed  -e 's/ /./' -e 's/\//./g' > time_stamps.txt
last_time_stamp=`sed -n '$'p time_stamps.txt`
sed  '$'d time_stamps.txt > temp0.txt
mv temp0.txt time_stamps.txt
last_time_stamp1=`sed -n '$'p time_stamps.txt`
sed -n '/'$last_time_stamp1'/,/'$last_time_stamp'/'p time.txt > last_half_hour.txt
sed  '1'd last_half_hour.txt > temp.txt
sed  '$'d temp.txt > temp1.txt
mv  temp1.txt last_half_hour.txt