You don't need a hash for that; a simple array will do.

Assume you want to check if column 4 is equal to 4, 5, .. N

• For each line in a file
  • Split up the line into its component fields
  • For each $index in the range 4 through N inclusive
    • Increment $count [$index ]

You can print $count out at the end. If you want to store each line that meets a certain criteria, make a two dimensional array (first dimension would be $index, the second the $count [$index ] value before you increment it).