doing arithmetics with columns

man bash

--

There're many variant methods to do the required operation. Here under are ideas came to me.

If you have 2 files (file1, file2), each of them has one column and u want to multiply each element here with each element there, just use nested for loop like follows:

 for i in `cat file1`
 do
   for j in `cat file2`
   do
     echo $i "*" $j "=" $(($i*$j))
   done
 done

Of course u can use any operation other than multiplication.

To multiply by constant, just use YoussefAssad code.

But, if each file contain multiple column, use awk (or cut) as follows:

 for i in `cat file1 | awk '{print $1}'`
 do
   for j in `cat file2 | awk '{print $1}'`
   do
     echo $i "*" $j "=" $(($i*$j))
   done
 done

piping to "awk '{print $x}'" extract the column x.

U could also piping to cut -f x -d y which will do the same where x is the column and y is a string (between doublequote) that sets the delimiter.

Otherwise, if file1 and file2 contain one column and u want to multiply each row in file1 to the corresponding column only in file2, use the following code:

 paste file1 file2 | awk '{print $1" * "$2" = "$1*$2}'

Wish this example codes make things more clear to u.