How to Add Calculations to a Bash Script

let "m = 4 * 1024"; echo $m

let "m = a % 100"

let "m += 15"

let "m++"

let "m--"

let "k = (m < 9) ? 0 : 1"

Floating Point Arithmetic in Bash

The let operator only works for integer arithmetic. For floating point arithmetic you can use for example the GNU bc calculator:

echo "32.0 + 1.4" | bc 

Backticks (back single quotes) can be used to evaluate an arithmetic expression as in this example:

echo `expr $m + 18`

m=`expr $m + 18`

Another way to evaluate arithmetic expressions is to use double parenthesis:

(( m *= 4 ))

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