Shell Programming and Scripting

#!/bin/bash
join -a1 -1 1 -2 1 -o "0 1.2 2.2" -e " " Prac1 Prac2 | sed '/^#/d' > temp
#use temp file.
#join -a1 -a2 -1 1 -2 1 -o "0 1.2 1.3 2.2" -e " " temp Prac3 | sed '/^#/d' > Marks
#sort -n Marks > Marks

a=8
b=16
c=8
ans=0
ans1=0
ans2=0
ans3=0
while read -n 8 file
do
if [ $a = $c ]; then
	echo "$file":
	c=`expr $c + 16`
fi
if [ $a = $b ]; then
	#echo this is 16
	ans=`echo "$file"`
	#echo $ans
	ans1=${ans:0:1}
	ans2=${ans:2:1}
	ans3=${ans:4:1}
	expr $ans1 + $ans2 + $ans3
	b=`expr $b + 16`
fi
#echo $a
#echo $b
a=`expr $a + 8`

done < Marks > Marks2