generate_tags.rb

namespace :tags do
  task :generate do
    puts 'Generating tags...'
    require 'rubygems'
    require 'jekyll'
    include Jekyll::Filters

    options = Jekyll.configuration({})
    site = Jekyll::Site.new(options)
    site.read_posts('')

    html =<<-HTML
---
layout: default
title: Tags
---

<h2>Tags</h2>

    HTML

    site.categories.sort.each do |category, posts|
      html << <<-HTML
      <h3 id="#{category}">#{category}</h3>
      HTML

      html << '<ul class="posts">'
      posts.each do |post|
        post_data = post.to_liquid
        html << <<-HTML
          <li>
            <div>#{date_to_string post.date}</div>
            <a href="#{post.url}">#{post_data['title']}</a>
          </li>
        HTML
      end
      html << '</ul>'
    end

    File.open('tags.html', 'w+') do |file|
      file.puts html
    end

    puts 'Done.'
  end
end

A way to do this jekyll only (without ruby), works on github, for example:

---
layout: default
title: Fastr Blog

---
<h2>Categories:</h2>
<ul>
{% for category in site.categories %}
  <li><a href="#{{ category | first }}">{{ category | first }}</a></li>
{% endfor %}
</ul>
<h2>Articles by Category:</h2>
<ul>
{% for category in site.categories %}
  <li><a name="{{ category | first }}">{{ category | first }}</a>
    <ul>
    {% for posts in category %}
      {% for post in posts %}
        <li><a href="{{ post.url }}">{{ post.title }}</a></li>
      {% endfor %}
    {% endfor %}
    </ul>
  </li>
{% endfor %}
</ul>
{% for post in site.categories.quickstart %}
<!-- h2><a href=".{{ post.url }}">{{ post.title }}</a></h2 -->
<!-- {{ post.content }} -->
{% endfor %}
Page generated: {{ site.time | date_to_string }}

I posted to the jekyll mailing list to find out how to get the name of category so that I don't have to hackishly treat it as an array, but no answer yet.

@coolja86 - That's fantastic! I had something similar working before I upgraded to Jekyll 0.6.2, but something in one of the intervening versions messed up the site.tags hash. Your hackish array treatment works almost perfectly.

One question… have you figured out a way to sort the tags? I used to be able to use for tags in site.tags|sort and that was it, but it doesn't work anymore. Have you had any luck?

Thanks!

@andrewheiss

I tried a few things, but I couldn't get it to work. Any progress?

After trying to make some Liquid filters, I finally got it to work using a patch to the Jekyll core. If you add elstudio's patch (http://github.com/mojombo/jekyll/issuesearch?state=open&q=sort+#issue/58), it sorts the tags hash using RBTree (you'll have to install that gem). Your tags should be sorted without any modification to your code.