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

my @words;
my %list;

unless ($ARGV[1]){
    print "Usage is oneword infile outfile\n";
    exit;
}
open (WORDLIST, "$ARGV[0]")||die "Could not open file $!";
open (OUTFILE, ">$ARGV[1]")||die "Could not open file $!";
while (<WORDLIST>){push (@words => $_)}
foreach (@words){$list{$_}=$list{$_}} #this works because if the hash key
                                      #exists already it is replaced!
foreach (keys %list){print OUTFILE;}