Monks:

I need to download some data files from a website, and would welcome any suggestions.

The website has three pull-down menus: firm name, date, and file format. I want to download data for every firm and date. In other words, firm1-June2001, firm1-July2001, …, firm1-December2011, firm2-June2001, firm2-July2001, …, firm2-December2011. I would also like to choose “dat” from the format pull-down menu, and need to press the download button to download the file to my machine.

I also would like to slow the download speed down so I don’t overload the website’s server, and have a file that indicates which firm-date files are downloaded and whether errors occurred. For instance, I want to distinguish between a missing file and a download error.

I am running this program on a Windows machine with Chrome.

I found the following code at http://www.perlmonks.org/?node_id=617277 and am looking for any suggestions on how to adapt it. The notations are my additions. 
#!/usr/bin/perl -w
use strict;
use LWP::UserAgent;

#$ is a scalar variable, key-->value, LWP is a virutal browser;
my $ua = LWP::UserAgent->new;

my $user = 'username';
my $pass = 'password';

my $URL = 'https://www.tta.thomson.com/msi/public1_5clients.html';
#Creating a file name from the URL;
my $filename = substr( $URL, rindex( $URL, "/" ) + 1 );
#Prints and /n adds new line;
print "$filename\n";
#Output filename into IN;
open( IN, ">$filename" ) or die $!;

print "Fetching $URL\n";

my $expected_length;
my $bytes_received = 0;

#Fetches a file from a website;
my $req = HTTP::Request->new(GET => $URL);
$req->authorization_basic($user, $pass);

my $res = $ua->request($req,
    sub {
        #@_ is plural of $_ 9 (default variable);
        my ( $chunk, $res ) = @_;
        # = assigns a variable, length is a length function, bytes;
        #_received number;
        $bytes_received += length($chunk);
        #printf is a special print function, SD Error stream, decimal;
        #number with percent;
        #symbol;
        unless ( defined $expected_length ) {
            $expected_length = $res->content_length || 0;
        }
        if ($expected_length) {
            printf STDERR "%d%% - ", 100 * $bytes_received / $expected
+_length;
        }
        print STDERR "$bytes_received bytes received\n";

        # XXX Should really do something with the chunk itself
        print IN $chunk;
    }
);

print $res->status_line, "\n";
#I think IN holds the file;
close IN;
exit;

[download]

In reply to How To Download DAT Files From Unsecured Website by Marjan

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