#!/usr/bin/perl

use strict;
use warnings;
use autodie;

#Get the filename from the first argument.
my ($filename) = @ARGV;

#open it to read it. 
open( my $input_data, "<", $filename );

#set up somewhere to store our count.
my %word_count;

#cycle through one line at a time.
while (<$input_data>) {
    chomp;
 
    #take each line, split it by spaces and 
    #count the number of occurances

    foreach my $word (split) {
        $word_count{$word}++;
    }
}

#print the results. Sort %word_count into count order. 
#(Descending) and print. 
foreach
    my $word ( sort { $word_count{$b} <=> $word_count{$a} } keys %word
+_count )
{
    print "$word = $word_count{$word}\n";
}
[download]