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

I know this thread is WAY old at this point, but I wanted to share a function I wrote that could help with this:

abs() { 
    [[ $[ $@ ] -lt 0 ]] && echo "$[ ($@) * -1 ]" || echo "$[ $@ ]"
}

This will take any mathematical/numeric expression as an argument and return the absolute value. For instance: abs -4 => 4 or abs 5-8 => 3