#!/bin/perl -w
use strict;
#for a csv file you can try something like this,
#but there are dozens of ways to do this.
#you should read a book called "Sam's learn perl in
#24 hours" (or similar title).

#variables you can change to suit your needs
my $column_separator = ",";
my $column_number = "3";
$column_number--;
my $file="filename.ext";
open(FILE,"<","$file");
my @lines=<FILE>;
close FILE;

foreach my $line (@lines){
 my @columns = split(/$column_separator/,"$line");
 print $columns[$column_number],"\n";
}