Here's my own implementation of a podcatcher I wrote in perl, based loosely on bashpodder. You can find more info on my blog at http://www.massyn.net/?p=83

#!/usr/bin/perl -w

my $version = "massyn.net philpodder/1.6 (" . $^O . ")";

# ======================================================== #
# This script is FREEWARE.  You are allowed to use this    #
# code in any way, commercial or non-commercial, as long   #
# as credit is given to me.  I still own the copyright.    #
#                                                          #
# Even though every attempt has been made to ensure this   #
# script is bug free, problems sometimes to come up.   I   #
# can not be held responsible for any damage or disruption #
# this script may cause you.  The code is provided open    #
# and free.  It is assumed that you will at least attempt  #
# to test the code first, before running it on any system. #
# Use the code at your own risk.  If you don't agree, then #
# don't use it.  It's as simple as that.                   #
#                                                          #
# Feel free to leave any comments about the script on the  #
# www.massyn.net website.  I trust that you will be able   #
# to use the script to your benefit.                       #
#                                                          #
# Phil Massyn                                              #
# http://www.massyn.net                                    #
# December 31st, 2006                                      #
# Sydney, AUSTRALIA                                        #
#                                                    _     #
#   _ __ ___   __ _ ___ ___ _   _ _ __    _ __   ___| |_   #
#  | '_ ` _ \ / _` / __/ __| | | | '_ \  | '_ \ / _ \ __|  #
#  | | | | | | (_| \__ \__ \ |_| | | | |_| | | |  __/ |_   #
#  |_| |_| |_|\__,_|___/___/\__, |_| |_(_)_| |_|\___|\__|  #
#                           |___/                          #
#                                                          #
# ======================================================== #

# Phil's Podder - a simple perl podcast aggregator 
# 
# This script requires wget.  I find wget is very good at
# getting files downloaded.  If you don't have wget, do 
# a Google search for it, and get it installed.
#
# The script is loosely based on BashPodder.
# http://linc.homeunix.org:8080/scripts/bashpodder/
# I just found that, first of all, BashPodder relied
# heavily on Unix commands.  I've consolidated all of
# that using perl commands.  I also found BashPodder
# to be very cruel when running it the first time.  It
# will download everything.  It also tends to download
# everything again, should it crash half way through a
# download.
#
# The $config parameter points to the text file containing
# the list of feeds to check.  You maintain this file.
#
# The $log parameter points to the log file, that contains
# all URLs already downloaded.
#
# $datadir points to the directory where the podcasts will
# be downloaded to.
#
# Revision update
# ------------------------------------------------------
# 1.1 - 2007/02/24
# A huge thanks to Foonley from the Whirlpool forums for
# some suggestions on how to clean up the code, and to
# fix some issues.  For one, I've added strict.
# 
# 1.2 - 2007/05/18
# Added .busy files (so I don't update it by accident)
# 
# 1.3 - 2007/07/04
# Added ignoring of # in config file
#
# 1.4 - 2007/07/20
# Added reset command line option
#
# 1.5 - 2007/07/28
# Changed .busy to be .$$.busy, to help with duplicate downloads
#
# 1.6 - 2007/08/21
# Removed reset (because that's what nograb does!).
# Added .$$.mp3 if the file already exists
#
# ====================================================== #
use strict;

my $config    = "$0.conf";
my $log         = "$0.logs";

# For Linux, this is the path I use -- adjust it accordingly...
my $datadir = "/home/phil/www/tmp/podcast";

# If you're on a Windows machine, you need to provide that directory
#my $datadir = "c:/temp";

my $podcast;
my $url;
my $line;
my $file;
my $xml;

## Check if the datadir exists...

die "Data directory $datadir does not exist...\n" unless -d $datadir;
die "No config file found ($config)...\n" unless -f $config;

## If we're adding a new podcast, add it to our config file
## if it were read successfully

if(!$ARGV[0])
{
    # read the config file

        open(my $IN, "$config");
        foreach $podcast (<$IN>)
        {
                chomp($podcast);
        if($podcast !~ /^#/)
        {
                    parse_xml($podcast);
        }
        }
        close $IN;
}
elsif($ARGV[0] eq "add")
{
    if(parse_xml($ARGV[1]) == 0)
    {
        add_to_db($config,$ARGV[1]);
    }
}
else
{
    die "Unknown parameter.";
}
exit(0);

# ============================================== #

# This function reads the XML file, and extracts the enclosure tags UR
+L

sub parse_xml
{
    $podcast = $_[0];

    print "$podcast\n";

    # get the XML file...
    undef $xml;
    $xml = `wget --timeout 10 -t 3 -U \"$version\" -q \"$podcast\" -O 
+-`;    
    if($? == 0)
    {
        # go through each line, by splitting in the > character.  Reas
+on : one podcast
        # feed had everything in one line, so this function didn't wor
+k as expected.
        
        foreach $line (split(/\>/,$xml))
        {
            chomp($line);

            $line =~ tr /\r/\n/;
            $line =~ tr /\'/\"/;

            # if the line contains <enclosure and url=", grab the URL 
+in there. podomatic
            # for example puts the length just after enclosure...

            if($line =~ m/\<enclosure/ && $line =~ /url="(.+)"/i)
            {
                handle_url((split/\"/,$1)[0]);
            }
        }
        return 0;
    }
    else
    {
        print "   ERROR reading the XML feed!\n";
        return 1;
    }
}
# ------------------------------------------------ #

# This function attempts to download the URL.  If it already got downl
+oaded,
# it will be skipped.

sub handle_url
{
    $url = $_[0];

    # is the url in the log file?
    if(is_in_db($log,$url) eq "YES")
    {
        #print "   Skipping : $url\n";
        return;
    }

    # get the file name from the URL
    $file = substr($url,rindex($url,"/")+1);

    if(!$ARGV[0])
    {
                print "   Downloading : $url\n";
                `wget -t 10 --timeout 20 -U \"$version\" -c -q -O $dat
+adir/$file.$$.busy "$url"`;
                if($? == 0)
                {
                        add_to_db($log,$url);
            if(!-f "$datadir/$file")
            {
                rename("$datadir/$file.$$.busy","$datadir/$file");
            }
            else
            {
                my $id = $$;
                my $newfile = $file;
                $newfile =~ s/(\.\S+)$/.$id$1/g;
                rename("$datadir/$file.$$.busy","$datadir/$newfile");
            }
                }
                else
                {
                        print "   WARNING : Could not download $url!!\
+n";
                }
    }
    elsif($ARGV[0] eq "nograb" || $ARGV[0] eq "add")
    {
        print "   Ignoring : $url\n";
        add_to_db($log,$url);
    }
    else
    {
        die "Unknown parameter\n";
    }
}
# ----------------------------------------------- #

# These two functions are just a silly way to implement a single field
+, single table
# database.  They are used mainly for the logs.  They ensure that only
+ unique fields 
# are added to the database.

sub add_to_db
{
        if(is_in_db($_[0],$_[1]) eq "NO")
        {
                open(my $ADD_TO_DB,">>$_[0]");
                print $ADD_TO_DB "$_[1]\n";
                close $ADD_TO_DB;
        }
}

sub is_in_db
{
        open(my $IS_IN_DB,"$_[0]");
        foreach (<$IS_IN_DB>)
        {
                chomp;
                if($_ eq $_[1])
                {
                        close $IS_IN_DB;
                        return "YES";
                }
        }
        close $IS_IN_DB;
        return "NO";
}
[download]

Thanks!

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The more I learn the more I realise I don't know.
- Albert Einstein