From: Andrew Porter <aporter@...>
Date: 2008-05-29T12:48:47+09:00
Subject: Re: Find/Replace In Files Using Lookup Table

Thanks, Eric. These are excellent tips.


On May 28, 2008, at 5:05 PM, Eric I. wrote:

> On May 28, 6:18 pm, Andrew Porter <apor...@eyequeue.net> wrote:
>> I have a directory full of HTML files. Some have anchor tags (<a
>> href="directory/filename.html">), some do not. I also have a tab-
>> delimited text file with—among other things—an ID, title, and  
>> filename.
>>
>> What I need to do is create a script that will:
>>
>> 1. Search all of the HTML files in a directory for anchor tags
>> 2. Strip out the file name from the href attribute
>> 3. Use the file name to look up the correlating ID in the lookup file
>> 4. Replace the contents of the href attribute with the ID
>>
>> Being new to Ruby and command-line scripting, I'm not sure where to
>> begin looking for examples of how to do this. Any help is  
>> appreciated.
>
> Obviously your goal is to this processing.  But are you hoping to use
> this to learn Ruby?  If so, this is a nice-sized project that will
> help you to learn the language.  Here are some pointers to help you
> figure out where to look or start with certain aspects of the project
> (the numbers match up with your numbers above):
>
> 1. To get a list of all of the HTML files in a given directory, you
> can use Dir.glob.
>
> 2. To parse an HTML file you can use the hpricot gem.  Alternatively,
> you could open the file and use regular expressions.
>
> 3. To have read your tab-delimited file at the start of the program,
> you can use the CSV class in the standard library or the fastercsv
> gem.  You can put the data into a hash where the file name is the key
> and the ID is the value.  Lookup becomes trivial then.
>
> 4. Depending on whether you're using hpricot or regular expressions
> will determine how you do this.  If you're using regular expressions,
> you might want to do a gsub! call with a block that would allow you to
> do your lookup and replacement.
>
> Some relevant information sources:
>
> You should have one of the Ruby books to help you with basic syntax
> and all that.  They will also help you with regular expressions,
> hashes, and file I/O.
>
> Documentation on File (and IO), Dir, CSV, Regexp, and Hash, you can
> use:
>
>    http://ruby-doc.org/core/
>
> For hpricot:
>
>    http://code.whytheluckystiff.net/hpricot/
>
> For fastercsv:
>
>    http://fastercsv.rubyforge.org/
>
> I hope that's helpful,
>
> Eric
>
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