Jekyll display posts by category

Got it! Needed an intermediate posts loop before listing out individual posts

<ul>
{% for category in site.categories %}
  <li><a name="{{ category | first }}">{{ category | first }}</a>
    <ul>
    {% for post in category.last %}
      <li><a href="{{ post.url }}">{{ post.title }}</a></li>
    {% endfor %}
    </ul>
  </li>
{% endfor %}
</ul>

fyi, if anyone wants to just list the posts in one category, this works (differs from above example as the category returns a list of posts...

<p>Posts in category "basic" are:</p>

<ul>
  {% for post in site.categories.basic %}
    {% if post.url %}
        <li><a href="{{ post.url }}">{{ post.title }}</a></li>
    {% endif %}
  {% endfor %}
</ul>

Now there is an official plugin available for this. jekyll-archives.

In order to make use of it,

Add jekyll-archives to your Gemfile and _config.yml file.

add a configuration something similar to the below as per your need.

jekyll-archives:
  enabled: all
  layouts:
    year: archive/year
    month: archive/month
    day: archive/day
    tag: archive/tag
    category: archive/category
  permalinks:
    year: '/:year/'
    month: '/:year/:month/'
    day: '/:year/:month/:day/'
    tag: '/tags/:name/'
    category: '/category/:name/'

The layouts can make use of the following page attributes depending on the archive type.

• page.type - (Any one fo the following. year, month, day, tag, category)
• page.title - (Only available for the type tag and category. Nil otherwise.)
• page.date - (Depending on page.type you should parse out the date and month field )
• page.posts - (List of posts for this archive)

Here is a sample layout for archive based on years

<h1>Archive of posts from {{ page.date | date: "%Y" }}</h1>
<ul class="posts">
{% for post in page.posts %}
  <li>
    <span class="post-date">{{ post.date | date: "%b %-d, %Y" }}</span>
    <a class="post-link" href="{{ post.url | prepend: site.baseurl }}">{{ post.title }}</a>
  </li>
{% endfor %}
</ul>