Enabling related post on octopress and Mac OS X

Octopress is a powerful framework built over Jekyll to create static websites. I used Octopress too for armoredcode.com. All posts are written with vim using markdown with some javascript to integrate with disqus for comments, github or twitter.

No database, just a webserver and a bunch of html files you’re reading right now.

Yesterday I turned on option to show related posts. Let’s see how.

Yesterday while I was editing octopress wiki page to add highlight plugin I wrote in the list I found something I was looking for from months: a plugin for related posts.

Showing related posts is one of the key features I was missing more after I switched from wordpress to statically generated websites.

Looking at the plugin’s README I was surprised in finding that related posts is a builtin feature wordpress already have. To enable post classification you have just to turn the lsi parameter on in your _config.yml.

lsi: true

However internal engine to classify posts is very slow and octopress itself suggests you to install Ruby/GSL bindings to speed up the process.

Installing GNU Scientific Library

Before installing the ruby binding you have to install the GNU Scientific Library that it will be used to classify posts.

If you’re using brew as package manager, and you really should do, installing the library it’s just a command away:

$ brew install gsl

On my Mac OS X 10.6, brew complains that some directory wasn’t writable so you’ve to manually chmod them giving your user a temporary writing access. Make sure to revert the permission schema in order not to make your directory permissions too loose.

If you’re not using brew you can follow the Unix way to install GSL: download the tarball from the website, unpack it, launch configure then make then make install as root.

For other Mac OS X package managers I don’t know if they can install GSL, maybe you can try on your own.

Installing the Ruby/GSL binging

To let this step to pass, make sure the gsl-config executable is in your $PATH. Important note: highlight if you’re using rvm make sure to switch to the ruby version and eventually to the gemset you’re using with octopress or it won’t find GSL when running the classifier.

Before installing Ruby/GSL, if you’re under Mac OS X you have to apply this patch to the source code. Just download and use the venerable patch command:

$ patch -p1 < ~/Downloads/gist1217974-b9f7ea8c9372d321c81fb8c12a272d76ecd9f1ef/rb-gsl.patch

Patch applies smoothly and you can proceed configuring the package:

$ ruby setup.rb config

Setting it up and compiling with:

$ ruby setup.rb setup 

My system has this gcc version, it produces some warning while compiling that you can safetly ignore:

$ gcc -version                                                                             
i686-apple-darwin11-llvm-gcc-4.2: no input files

Last step is to install Ruby/GSL binding, you must to be root for this:

$ sudo ruby setup.rb install

Now everything should work and every time you run a generate command from your octopress root, Ruby/GSL should be used as classifier engine and posts correlation should be very fast.

Now it’s time to show your related posts.

Since this plugin makes me to discover the related post feature in octopress I really encourage you to use it.

For my own taste, I don’t like to show related post in an aside element, rather I want to show right before your post footer.

The file you need to modify, if you follow me is source/_layouts/post.html. Please bear in mind that if you upgrade octopress from github automatically you may overwrite this file, so it’s better for you to save your theme in the .themes directory, hacking there and then apply the theme in order to store your changes somewhere.

``` html source/_layouts/post.html

{ % include article.html % } ... ``` Enjoy it!

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