Looping over pairs of values in bash

Question

I have 10 text files and I want to paste each file with its pair, such that I have 5 total files.

I tried the following:

for i in 4_1 5_         


        

Answer 1

If you want to use one variable and perform and action with it, you just need to use one loop:

for file in 4 5 6 7 8
do
   paste "${file}_1" "${file}_2"
done

This will do

paste 4_1 4_2
paste 5_1 5_2
...