A little programming exercise to keep the coder alive ... Problem: DJ Marky's podcast gone in iTunes. Suggested fix: batch-download podcast feed. Requirement: 140 characters ("golf") solution to tweet it around ... no seriously: I wanted to see how to solve this in a nice one-liner (so no fancy input options for this script ... google on: 'script download podcast feed <your preferred coding tool>' for more advanced stuff already out there).

This is what I have come up with so far:

wget $(wget -q -O - feed_url | sed -n 's/.*enclosure.*url="\([^"]*\)" .*//p')

Read this from the inside-out: get the feed and dump to standard output (-O) and without other noise (-q), filter the enclosure tags and get the URL out of it (the enclosure tag is what the feeds have in common. See the RSS spec). This is wrapped in a subprocess ( $(...) ) and provides a list of mp3 files which is fed to the outer wget which starts to download them one by one.

Although I tend to use perl -pe in one-liners for its powerful regex engine, I learned the useful -n / p combo of sed to combine grep and replacing strings in one go (suggestions in perl are welcome in the comments ...)

Extending it to a small script to receive a feed as input as first command line argument ($1):
podcast_feed.sh

#!/bin/bash
wget $(wget -q -O - $1 | sed -n 's/.*enclosure.*url="\([^"]*\)" .*//p')

Testing a 'dry run' (don't download / print-only) version with various feeds (just take the outer wget off)

podcast_feed_print.sh

#!/bin/bash
wget -q -O - $1 | sed -n 's/.*enclosure.*url="\([^"]*\)" .*/# /p'

Test it with 5 feeds:

$ for pc in $(cat podcast_feed_test.txt);
> do echo "testing "$pc && ./podcast_feed_print.sh $pc | head -2 && echo
> done

testing http://djmarky.com.br/podcast/podcast.xml
# http://p.audio.uol.com.br/djmarky/podcast/markys_podcast_august_2013.mp3
# http://p.audio.uol.com.br/djmarky/podcast/marky_july_2013.mp3

testing http://feeds.feedburner.com/spipodcast
# http://traffic.libsyn.com/patflynn/SPI092-Psychology_of_Selling_How_to_Price.mp3
# http://traffic.libsyn.com/patflynn/SPI091-Mixing_Online_Business_with_Offline_Marketing_Strategies.mp3

testing http://www.fatburningman.com/feed/podcast/
# http://traffic.libsyn.com/fatburningman/99DrDavidPerlmutter.mp3
# http://traffic.libsyn.com/fatburningman/98ChrisKresser.mp3

testing http://lewishowes.com/feed/podcast/
# http://media.blubrry.com/the_school_of_greatness/www.podtrac.com/pts/redirect.mp3/feeds.soundcloud.com/stream/126379015-lewishowes-sean-stephenson-how-to-leave.mp3
# http://media.blubrry.com/the_school_of_greatness/www.podtrac.com/pts/redirect.mp3/feeds.soundcloud.com/stream/124890483-lewishowes-daniel-negreanu.mp3

testing http://feeds.feedburner.com/se-radio
# http://feedproxy.google.com/~r/se-radio/~5/mqwgeoTD1sc/SE-RadioEpisode199-MichaelStonebraker.mp3
# http://feedproxy.google.com/~r/se-radio/~5/rcNWFPGdwrk/SE-RadioEpisode198-WilVanDerAalst.mp3

Works, and with 86 characters quite small!

Downloading podcasts now  ...

$ podcast_feed.sh http://djmarky.com.br/podcast/podcast.xml

--2013-12-27 00:46:35--  http://p.audio.uol.com.br/djmarky/podcast/markys_podcast_august_2013.mp3

Resolving p.audio.uol.com.br... 200.147.98.177, 200.147.1.156, 200.147.1.157, ...

Connecting to p.audio.uol.com.br|200.147.98.177|:80... connected.

HTTP request sent, awaiting response... 200 OK

Length: 89803694 (86M) [audio/mpeg]

Saving to: ‘markys_podcast_august_2013.mp3’
..
..

The code used in this post can be found here.


Bob Belderbos

I build useful apps and share my learning About me