How to add values in a variable in Unix shell scripting?

Question

I have two variables called count1 and count7

count7=0
count7=$(($count7 + $count1))

This shows an error \"expression is not complete; more tok

Answer 1

the above script may not run in ksh. you have to use the 'let' opparand to assing the value and then echo it.

val1=4

val2=3

let val3=$val1+$val2

echo $val3 

Answer 2

 echo "$x"
    x=10
    echo "$y"`enter code here`
    y=10
    echo $[$x+$y]

Answer: 20

Answer 3

var=$((count7 + count1))

Arithmetic in bash uses $((...)) syntax.

You do not need to $ symbol within the $(( ))