The static blog generator, Octopress, does not generate per category RSS feeds by default. I thought I would need a plugin to do this but it is quite easy and a plugin is overkill. All that you need to do is create a feed file with the appropriate filtering to limit the category.

To create a per category feed, copy the default feed source/atom.xml file to say source/emacs.xml. I updated the <title> value and the for post loop to only use the emacs categories. Here is my file:

<?xml version="1.0" encoding="utf-8"?>
<feed xmlns="">

  <title>{{ site.title | xml_escape }} - Emacs</title>
  <link href="{{ site.url }}/atom.xml" rel="self"/>
  <link href="{{ site.url }}/"/>
  <updated>{{ site.time | date_to_xmlschema }}</updated>
  <id>{{ site.url }}/</id>
    <name>{{ | xml_escape }}</name>
    {% if %}
      <email>{{ | xml_escape }}</email>
    {% endif %}
  <generator uri="">Octopress</generator>

  {% for post in site.categories.emacs limit: 20 %}
    <title>{{ post.title | xml_escape }}</title>
    <link href="{{ site.url }}{{ post.url }}"/>
    <updated>{{ | date_to_xmlschema }}</updated>
    <id>{{ site.url }}{{ }}</id>
    <content type="html">{{ post.content | expand_urls: site.url | xml_escape }}</content>
  {% endfor %}