Shell Programming and Scripting

#!/bin/bash
SysMth=`date +%m`
prior6month=`echo -e "07\n08\n09\n10\n11\n12\n01\n02\n03\n04\n05\n06\n07\n08\n09\n10\n11\n12\n" | head -$SysMth | tail -6 | head -1`
totrec=`wc -l records.txt | awk '{print $1;exit}'`
i=1
rm old_records.txt
rm records_new.txt
cp records.txt records_copy.txt
touch old_records.txt
while [ $i -le $totrec ];do
curyear=`date +%Y`
rec=`head -n$i records_copy.txt | tail -1`
recdate=`head -n$i records_copy.txt | tail -1 |  awk '{print $2;exit}'`
recyear=`echo $recdate | awk '{print substr($0,7,4);exit}'`
recmonth=`echo $recdate | awk '{print substr($0,1,2);exit}'`
recday=`echo $recdate | awk '{print substr($0,4,2);exit}'`
if [ $SysMth -gt 06 ]; then
 if [ $prior6month -lt $recmonth ]; then
 echo $rec >> old_records.txt
 echo "Record older than 6 months"
 else
 echo "Record not older than 6 months"
 fi
else 
 if [ $prior6month -gt $recmonth ]; then
  if [ $recyear -lt $curyear ]; then
   echo `head -n$i records_copy.txt | tail -1` >> old_records.txt
   echo "Record older than 6 months"
  else   
   echo "Record not older than 6 months"
  fi 
 else
 echo `head -n$i records_copy.txt | tail -1` >> old_records.txt
 echo "Record older than 6 months"
 fi
fi
i=$(($i+1)) 
done
comm -3 records_copy.txt old_records.txt > records_new.txt
cat old_records.txt
echo
echo
cat records_new.txt