title: Linux utility for changing text in file
body: <p>I'm on linux Fedora having <code>a.dat</code> text file, which is a table of numbers. I have at columns 1 and 2 very big numbers, greater than <code>2000000</code>, all the other numbers are smaller than <code>1000</code>. I want to use linux utility which can open a file, search it for containing large numbers (condition is <code>&gt;2000000</code>) and substitute each found number by the value of a counter which is incremented each time the number is substituted.</p>
  
  <p>Is it possible todo in a terminal using maybe <code>grep</code> and how it can be done?</p>