Bash, how can I apply one arithmetic expression to every line?

Question

I have two scripts, A and B.

I want to execute them and read respectively two values. V and VALS.

V is just a floating point number, let's say 0.5

VALS has the following format:

1 10
2 20
3 60
4 45

and so on.

What I'm trying to do is to get a new variable where the second column of VALS (10, 20, ...) is divided by V.

As I understand this can be implemented with a mix of xargs and cut but I'm not really familiar with these tools.

#!/bin/bash

V=`./A`
VALS=`./B`
RESULT=#magic happens

The final result with the previous data should be:

1 20
2 40
3 120
4 90

Answer 1

Bash's builtin arithmetic expansion only works for integers. You can use awk for data extraction and floating point numbers.

V=`./A`
# No VALS needed
RESULT=($(./B | awk "{print \$2 / $V"}))

Note the escaped dollar sign in \\$2 .