bash arithmetic expressions with variables

Question

I am having troubles with the arithmetic expressions in a bash file (a unix file .sh).

I have the variable \"total\", which consists of a few numbers separated by sp

Answer 1

There are a number of ways to perform arithmetic in Bash. Some of them are:

dollar=$(expr $dollar + $a)
let "dollar += $a"
dollar=$((dollar + a))
((dollar += a))

You may see more on the wiki. If you need to handle non-integer values, use a external tool such as bc.

Answer 2

Wrap arithmetic operations within ((...)):

dollar=0
for a in $total; do
  ((dollar += a))
done