Railscast has a podcast on iTunes which lets you download all past episodes and thus this post is moot. But, I thought, what if it wasn’t? What if I found a cool site with a bunch of media files I want to download? I knew wget can do this but it’s been a while. So here’s what I did.

First I downloaded the archive page. It’s full of links to other pages which have the .mov media files on it. But I really needed a list of those pages within the archive page. Ok, I wget’d the archive html source page in a file named archive.txt: curl -o archive.txt http://railscasts.com/episodes/archive

However this page is full of html source and all I need is the list of episodes. So a simple: grep href urls.txt|grep episodes > urls_href.txt gets me that. But it’s really full of text that looks like this: [My Favorite Web Apps in 2009](/episodes/195-my-favorite-web-apps-in-2009)

Ok now I just need to trim all this crap out. First, there’s a bunch of whitespace out front in the links. Let’s use sed inline. This works on OSX and Linux but won’t work on Solaris (inline boo). sed -ie 's/^[ ]*//' urls_href.txt. Now we’re missing a those spaces out front.

Ok, now we need to trim down to the relative link to the episode. We want a URL that looks like: http://railscasts.com/episodes/30-pretty-page-title

So at this point sed was failing me because the regex syntax is different than I’m used to. So let’s switch to perl. cat urls_href.txt | perl -e 'while(<>) { s/\<a\s*(.*)\>(.*)\<\/a\>/$1/; print}' > urls_href_clean.txt

We’re almost there. We have URLs that look like this:


We need a prefix of the domain and to get rid of those quotes: ` cat urls_href_clean.txt | perl -e ‘while(<>) { s/href=/http:\/\/railscasts.com/; s/"//; s/"//; print}’ > urls_href_super_clean.txt `

Despite our horribly unmaintainable “super” naming convention, we now have a text file full of URLs that looks like this:



Fire wget using our text file as input (-i). Recurse (-r), go only two levels deep (-l), don’t download the file if we have one that’s newer and use timestamps to make this possible (-Nc), span hosts (-H), no directories (-nd), disrespect the robots.txt file (-erobots=off) and look for only .mov files (-A). wget -r -erobots=off -l2 -H -Nc -nd -A.mov -i urls_href_super_clean.txt

You might want to create a working directory for this before you run it. And probably run it under “screen” if you have that command. After you do, you’ll eventually you’ll have a directory full of railscasts. Or, you could just subscribe to their feed on iTunes. Getting it through iTunes is a lot easier but that wasn’t the point.