#!/usr/bin/perl
use strict;

my $file    = shift or die "Need a filename!\n";
my $columns = shift or die "How many columns?\n";
my $newfile = "$file.new";

open(F, "$file")     or die "Could not open $file: $!\n";
open(G, ">$newfile") or die "Could not create $newfile: $!\n";

## Set the first row as column headings:
print G join("\t", (split(/\t/,<F>,$columns+1))[0..$columns-1]), "\n";

## Rewind for the first line's data
seek(F,0,0);

## Now grab only the data from the rest:
print G (split(/\t/,$_,$columns+1))[$columns] while <F>;

close(F); close(G);