From: William James <w_a_x_man@...>
Date: 2006-08-02T16:15:09+09:00
Subject: Re: super-newbee Ruby regex help?

Aaron Reimann wrote:
> This is pretty complex considering that I am just now reading "Learn to
> Program" by Chris Pine (it is a book teaching you how to program in
> Ruby).  It is very basic.  I am somewhat good with PHP but and wanting
> to move into RoR and want to learn Ruby before I learn Rails.
>
> Anyway, I found a real life situation where I think Ruby could do this
> very quickly (and if I need to do it again, I can just run the script).
>  I need to remove some stuff from a text file.  Simple huh?  Here is
> the site that I need the list from:
>
> http://edge.i-hacked.com/250-working-proxies-for-safe-web-access-from-work-or-school
>
> In that page there is one line of "code" that has all of the
> links...here is part of it:
> <a href="http://www.3proxy.com">3 Proxy</a> || <a
> href="http://www.3proxy.net">3 Proxy</a> || <a
> href="http://www.3proxy.org">3 Proxy</a>
>
> I have taken just that line and saved that as a text file.
>
> I need to strip everything where I wind up with this:
> 3proxy\.com
> 3proxy\.net
> 3proxy\.org
> 4proxy\.com
>
> I will be taking that list (all 300 of them) and adding them to my
> content filtering box.  That way, all of these sites will be blocked.
>
> Do you guys know of any sites that might have a similar situation where
> I can see the code?  or have any of you done something similar?  I can
> probably modify stuff to make it fit my needs, but stuff like
> http://www.regular-expressions.info/ruby.html doesn't give me enough
> info to start.
>
> what i have right now is: file = File.open("list.txt","w")

If the file already exists, you'll destroy it by using the "w" option.
Since some of the anchor tags span more than one line,
let's read the whole file at once:

p IO.read( 'list.txt' ).
scan( %r{<a \s+ href="http://www\.([^"]*)"}x ).flatten