title: subtract columns from different files with awk
body: <p>I have two folders A1 and A2. The names and the number of files are same in these two folders. Each file has 15 columns. Column 6 of each file in folder 'A1' needs to substrate from the column 6 of each file in folder 'A2'. I would like to print column 2 and 6(after subtraction) from each file to a folder A3 with the same filenames. How can I do this with awk?</p>
  
  <pre><code>f1.txt file in folder A1
  
  RAM     AA   159.03  113.3  122.9  34.78    116.3 
  RAM     BB   151.24   70    122.9  142.78   66.4
  RAM     CC   156.70   80    86.2   70.1     54.8
  
  
    f1.txt file in folder A2    
  
  RAM     AA   110.05  113    122.9    34.78    116.3
  RAM     BB   150.15  70     122.9    140.60   69.4 
  RAM     CC   154.70  89.2   86.2     72.1     55.8
  
  
  desired output
  
  AA   0
  BB  2.18
  CC  -2
  </code></pre>