As you have seen my script, the output I am getting is in the while loop and that too in the variable called $peak. Now, I should match which key contains the $peak value. For example, I have got the output from $peak as 41.876000 45.063000 48.922000 44.042000 46.863000 44.727000 45.491000 46.154000 I should search all the keys which hold these values and print both key and value like 78.3 =====> 41.876000. In this the 78.3 is the "key" and 41.876000 is the "value" (output from $peak in the while loop).