Question

Say I have two files where there is one number per line

File 1      file 2
0.12        0.11     
0.121       0.454 
....        .... 

I want to create file or output difference between each number on to the screen, so that result looks like

 0.0099
-0.333
 ......

You can use bash/awk/sed

Answer 1

awk

awk '{getline t<"file1"; print $0-t}' file2  #file2-file1

Explanation: getline t <"file1" gets a line from file1 and puts its value to variable t. $0 is the current record of file2 that awk is processing. the rest is just subtraction and printing the result out.

Bash

exec 4<"file1"
while read -r line
do
    read -r s <&4
    echo "${line}-${s}" | bc
done <"file2"
exec >&4-