Shell Programming and Scripting

# !/usr/bin/ksh
#1

#The above line indicates the run

num=`sed 2q $0 | tail -1 | sed 's/#//'`
cnt=1
counter=0
sum=0

while read line
do
if [ $cnt -eq $num ]
then
  if [ $counter -le 1 ]
  then
     sum=$(($sum + $line))
     counter=$(($counter + 1))
  else
     break
  fi
else
  cnt=$(($cnt + 1))
fi
done < data

echo "sum is $sum"
cnt=$(($cnt + 2))

sed 1q $0 > tmp
echo "#$cnt" >> tmp
awk 'NR>2' $0 >> tmp

mv tmp $0
chmod 744 $0
exit 0

>cat data
2
3
4
5
6
7
8
9

>sum.ksh
sum is 5

>sum.ksh 
sum is 9

>sum.ksh 
sum is 13

#! /bin/ksh

echo "2
 3
 4
 5" | while read line
do
        NUM1=$line
        read line
        NUM2=$line
        SUM=$((NUM1+NUM2))
        echo $SUM
done

#! /bin/ksh

while read line
do
        NUM1=$line
        read line
        NUM2=$line
        SUM=$((NUM1+NUM2))
        echo $SUM
done < input.file