Absolute value of a number

Question

I want to take the absolute of a number by the following code in bash:

#!/bin/bash
echo \"Enter the first file name: \"
read first

echo \"Enter the second f         


        

Answer 1

You might just take ${var#-}.

${var#Pattern} Remove from $var the shortest part of $Pattern that matches the front end of $var. tdlp

---

Example:

s2=5; s1=4
s3=$((s1-s2))

echo $s3
-1

echo ${s3#-}
1