#!/usr/bin/perl -w
use strict;

my $datafile = shift;
my $want_col = shift;

open my $fh, '<', $datafile or die "$datafile: $!";

my $headings = <$fh>;
chomp $headings;
my @columns = split /\t/, $headings;

my %column;
@column{ @columns } = 0 .. $#columns;

die "Column '$want_col' not in $datafile" unless exists $column{ $want_col };

while ( <$fh> ) {
    chomp;
    print join "\t", (split /\t/)[ $column{ $want_col } ], "\n";
}