#!/usr/bin/perl
use warnings;
use strict;

open my $HUBFILE, '<', '1048_undefined.tsv' or die $!;
open my $OUT, '>', 'hubs.txt' or die $!;
while (my $line = <$HUBFILE>) {
    my $gene = $1 if $line =~ /\d \t (\w+) \t/x;
    print $OUT, $gene, "\n";
}
close $_ for ($HUBFILE, $OUT);