jekyll/site/_docs/templates.md

---
layout: docs
title: Templates
permalink: /docs/templates/
---

Jekyll uses the [Liquid](https://shopify.github.io/liquid/) templating language to
process templates. All of the standard Liquid [tags](https://shopify.github.io/liquid/tags/) and
[filters](https://shopify.github.io/liquid/filters/) are
supported. Jekyll even adds a few handy filters and tags of its own to make
common tasks easier.

## Filters

<div class="mobile-side-scroller">
<table>
  <thead>
    <tr>
      <th>Description</th>
      <th><span class="filter">Filter</span> and <span class="output">Output</span></th>
    </tr>
  </thead>
  <tbody>
    <tr>
      <td>
        <p class="name"><strong>Date to XML Schema</strong></p>
        <p>Convert a Date into XML Schema (ISO 8601) format.</p>
      </td>
      <td class="align-center">
        <p>
         <code class="filter">{% raw %}{{ site.time | date_to_xmlschema }}{% endraw %}</code>
        </p>
        <p>
          <code class="output">2008-11-07T13:07:54-08:00</code>
        </p>
      </td>
    </tr>
    <tr>
      <td>
        <p class="name"><strong>Date to RFC-822 Format</strong></p>
        <p>Convert a Date into the RFC-822 format used for RSS feeds.</p>
      </td>
      <td class="align-center">
        <p>
         <code class="filter">{% raw %}{{ site.time | date_to_rfc822 }}{% endraw %}</code>
        </p>
        <p>
          <code class="output">Mon, 07 Nov 2008 13:07:54 -0800</code>
        </p>
      </td>
    </tr>
    <tr>
      <td>
        <p class="name"><strong>Date to String</strong></p>
        <p>Convert a date to short format.</p>
      </td>
      <td class="align-center">
        <p>
         <code class="filter">{% raw %}{{ site.time | date_to_string }}{% endraw %}</code>
        </p>
        <p>
          <code class="output">07 Nov 2008</code>
        </p>
      </td>
    </tr>
    <tr>
      <td>
        <p class="name"><strong>Date to Long String</strong></p>
        <p>Format a date to long format.</p>
      </td>
      <td class="align-center">
        <p>
         <code class="filter">{% raw %}{{ site.time | date_to_long_string }}{% endraw %}</code>
        </p>
        <p>
          <code class="output">07 November 2008</code>
        </p>
      </td>
    </tr>
    <tr>
      <td>
        <p class="name"><strong>Where</strong></p>
        <p>Select all the objects in an array where the key has the given value.</p>
      </td>
      <td class="align-center">
        <p>
         <code class="filter">{% raw %}{{ site.members | where:"graduation_year","2014" }}{% endraw %}</code>
        </p>
      </td>
    </tr>
    <tr>
      <td>
        <p class="name"><strong>Where Expression</strong></p>
        <p>Select all the objects in an array where the expression is true. Jekyll v3.2.0 & later.</p>
      </td>
      <td class="align-center">
        <p>
         <code class="filter">{% raw %}{{ site.members | where_exp:"item",
"item.graduation_year == 2014" }}{% endraw %}</code>
         <code class="filter">{% raw %}{{ site.members | where_exp:"item",
"item.graduation_year < 2014" }}{% endraw %}</code>
         <code class="filter">{% raw %}{{ site.members | where_exp:"item",
"item.projects contains 'foo'" }}{% endraw %}</code>
        </p>
      </td>
    </tr>
    <tr>
      <td>
        <p class="name"><strong>Group By</strong></p>
        <p>Group an array's items by a given property.</p>
      </td>
      <td class="align-center">
        <p>
         <code class="filter">{% raw %}{{ site.members | group_by:"graduation_year" }}{% endraw %}</code>
        </p>
        <p>
          <code class="output">[{"name"=>"2013", "items"=>[...]},
{"name"=>"2014", "items"=>[...]}]</code>
        </p>
      </td>
    </tr>
    <tr>
      <td>
        <p class="name"><strong>XML Escape</strong></p>
        <p>Escape some text for use in XML.</p>
      </td>
      <td class="align-center">
        <p>
         <code class="filter">{% raw %}{{ page.content | xml_escape }}{% endraw %}</code>
        </p>
      </td>
    </tr>
    <tr>
      <td>
        <p class="name"><strong>CGI Escape</strong></p>
        <p>
          CGI escape a string for use in a URL. Replaces any special characters
          with appropriate %XX replacements.
        </p>
      </td>
      <td class="align-center">
        <p>
         <code class="filter">{% raw %}{{ "foo,bar;baz?" | cgi_escape }}{% endraw %}</code>
        </p>
        <p>
          <code class="output">foo%2Cbar%3Bbaz%3F</code>
        </p>
      </td>
    </tr>
    <tr>
      <td>
        <p class="name"><strong>URI Escape</strong></p>
        <p>
          URI escape a string.
        </p>
      </td>
      <td class="align-center">
        <p>
         <code class="filter">{% raw %}{{ "foo, bar \baz?" | uri_escape }}{% endraw %}</code>
        </p>
        <p>
          <code class="output">foo,%20bar%20%5Cbaz?</code>
        </p>
      </td>
    </tr>
    <tr>
      <td>
        <p class="name"><strong>Number of Words</strong></p>
        <p>Count the number of words in some text.</p>
      </td>
      <td class="align-center">
        <p>
         <code class="filter">{% raw %}{{ page.content | number_of_words }}{% endraw %}</code>
        </p>
        <p>
          <code class="output">1337</code>
        </p>
      </td>
    </tr>
    <tr>
      <td>
        <p class="name"><strong>Array to Sentence</strong></p>
        <p>Convert an array into a sentence. Useful for listing tags.</p>
      </td>
      <td class="align-center">
        <p>
         <code class="filter">{% raw %}{{ page.tags | array_to_sentence_string }}{% endraw %}</code>
        </p>
        <p>
          <code class="output">foo, bar, and baz</code>
        </p>
      </td>
    </tr>
    <tr>
      <td>
        <p class="name"><strong>Markdownify</strong></p>
        <p>Convert a Markdown-formatted string into HTML.</p>
      </td>
      <td class="align-center">
        <p>
         <code class="filter">{% raw %}{{ page.excerpt | markdownify }}{% endraw %}</code>
        </p>
      </td>
    </tr>
    <tr>
      <td>
        <p class="name"><strong>Smartify</strong></p>
        <p>Convert "quotes" into &ldquo;smart quotes.&rdquo;</p>
      </td>
      <td class="align-center">
        <p>
         <code class="filter">{% raw %}{{ page.title | smartify }}{% endraw %}</code>
        </p>
      </td>
    </tr>
    <tr>
      <td>
        <p class="name"><strong>Converting Sass/SCSS</strong></p>
        <p>Convert a Sass- or SCSS-formatted string into CSS.</p>
      </td>
      <td class="align-center">
        <p>
          <code class="filter">{% raw %}{{ some_scss | scssify }}{% endraw %}</code>
          <code class="filter">{% raw %}{{ some_sass | sassify }}{% endraw %}</code>
        </p>
      </td>
    </tr>
    <tr>
      <td>
        <p class="name"><strong>Slugify</strong></p>
        <p>Convert a string into a lowercase URL "slug". See below for options.</p>
      </td>
      <td class="align-center">
        <p>
         <code class="filter">{% raw %}{{ "The _config.yml file" | slugify }}{% endraw %}</code>
        </p>
        <p>
          <code class="output">the-config-yml-file</code>
        </p>
        <p>
         <code class="filter">{% raw %}{{ "The _config.yml file" | slugify: 'pretty' }}{% endraw %}</code>
        </p>
        <p>
          <code class="output">the-_config.yml-file</code>
        </p>
      </td>
    </tr>
    <tr>
      <td>
        <p class="name"><strong>Data To JSON</strong></p>
        <p>Convert Hash or Array to JSON.</p>
      </td>
      <td class="align-center">
        <p>
         <code class="filter">{% raw %}{{ site.data.projects | jsonify }}{% endraw %}</code>
        </p>
      </td>
    </tr>
    <tr>
      <td>
        <p class="name"><strong>Normalize Whitespace</strong></p>
        <p>Replace any occurance of whitespace with a single space.</p>
      </td>
      <td class="align-center">
        <p>
         <code class="filter">{% raw %}{{ "a \n b" | normalize_whitepace }}{% endraw %}</code>
        </p>
      </td>
    </tr>
    <tr>
      <td>
        <p class="name"><strong>Sort</strong></p>
        <p>Sort an array. Optional arguments for hashes: 1.&nbsp;property name 2.&nbsp;nils order (<em>first</em> or <em>last</em>).</p>
      </td>
      <td class="align-center">
        <p>
         <code class="filter">{% raw %}{{ page.tags | sort }}{% endraw %}</code>
        </p>
        <p>
         <code class="filter">{% raw %}{{ site.posts | sort: 'author' }}{% endraw %}</code>
        </p>
        <p>
         <code class="filter">{% raw %}{{ site.pages | sort: 'title', 'last' }}{% endraw %}</code>
        </p>
      </td>
    </tr>
    <tr>
      <td>
        <p class="name"><strong>Sample</strong></p>
        <p>Pick a random value from an array. Optional: pick multiple values.</p>
      </td>
      <td class="align-center">
        <p>
         <code class="filter">{% raw %}{{ site.pages | sample }}{% endraw %}</code>
        </p>
        <p>
         <code class="filter">{% raw %}{{ site.pages | sample:2 }}{% endraw %}</code>
        </p>
      </td>
    </tr>
    <tr>
      <td>
        <p class="name"><strong>Array Filters</strong></p>
        <p>Push, pop, shift, and unshift elements from an Array.</p>
        <p>These are <strong>NON-DESTRUCTIVE</strong>, i.e. they do not mutate the array, but rather make a copy and mutate that.</p>
      </td>
      <td class="align-center">
        <p>
          <code class="filter">{% raw %}{{ page.tags | push: 'Spokane' }}{% endraw %}</code>
        </p>
        <p>
          <code class="output">['Seattle', 'Tacoma', 'Spokane']</code>
        </p>
        <p>
          <code class="filter">{% raw %}{{ page.tags | pop }}{% endraw %}</code>
        </p>
        <p>
          <code class="output">['Seattle']</code>
        </p>
        <p>
          <code class="filter">{% raw %}{{ page.tags | shift }}{% endraw %}</code>
        </p>
        <p>
          <code class="output">['Tacoma']</code>
        </p>
        <p>
          <code class="filter">{% raw %}{{ page.tags | unshift: "Olympia" }}{% endraw %}</code>
        </p>
        <p>
          <code class="output">['Olympia', 'Seattle', 'Tacoma']</code>
        </p>
      </td>
    </tr>
  </tbody>
</table>
</div>

### Options for the `slugify` filter

The `slugify` filter accepts an option, each specifying what to filter.
The default is `default`. They are as follows (with what they filter):

- `none`: no characters
- `raw`: spaces
- `default`: spaces and non-alphanumeric characters
- `pretty`: spaces and non-alphanumeric characters except for `._~!$&'()+,;=@`

## Tags

### Includes

If you have small page fragments that you wish to include in multiple places on
your site, you can use the `include` tag.

{% highlight liquid %}
{% raw %}{% include footer.html %}{% endraw %}
{% endhighlight %}

Jekyll expects all include files to be placed in an `_includes` directory at the
root of your source directory. This will embed the contents of
`<source>/_includes/footer.html` into the calling file.

<div class="note">
  <h5>ProTip™: Use variables as file name</h5>
  <p>

    The name of the file you wish to embed can be literal (as in the example above),
    or you can use a variable, using liquid-like variable syntax as in
    <code>{% raw %}{% include {{my_variable}} %}{% endraw %}</code>.

  </p>
</div>

You can also pass parameters to an include. Omit the quotation marks to send a variable's value. Liquid curly brackets should not be used here:

{% highlight liquid %}
{% raw %}{% include footer.html param="value" variable-param=page.variable %}{% endraw %}
{% endhighlight %}

These parameters are available via Liquid in the include:

{% highlight liquid %}
{% raw %}{{ include.param }}{% endraw %}
{% endhighlight %}

#### Including files relative to another file

You can also choose to include file fragments relative to the current file:

{% highlight liquid %}
{% raw %}{% include_relative somedir/footer.html %}{% endraw %}
{% endhighlight %}

You won't need to place your included content within the `_includes` directory. Instead,
the inclusion is specifically relative to the file where the tag is being used. For example,
if `_posts/2014-09-03-my-file.markdown` uses the `include_relative` tag, the included file
must be within the `_posts` directory, or one of its subdirectories. You cannot include
files in other locations.

All the other capabilities of the `include` tag are available to the `include_relative` tag,
such as using variables.

### Code snippet highlighting

Jekyll has built in support for syntax highlighting of over 60 languages
thanks to [Rouge](http://rouge.jneen.net). Rouge is the default highlighter
in Jekyll 3 and above. To use it in Jekyll 2, set `highlighter` to `rouge`
and ensure the `rouge` gem is installed properly.

Alternatively, you can use [Pygments](http://pygments.org) to highlight
your code snippets. To use Pygments, you must have Python installed on your
system, have the `pygments.rb` gem installed and set `highlighter` to
`pygments` in your site's configuration file. Pygments supports [over 100
languages](http://pygments.org/languages/)

To render a code block with syntax highlighting, surround your code as follows:

{% highlight liquid %}
{% raw %}
{% highlight ruby %}
def foo
  puts 'foo'
end
{% endhighlight %}
{% endraw %}
{% endhighlight %}

The argument to the `highlight` tag (`ruby` in the example above) is the
language identifier. To find the appropriate identifier to use for the language
you want to highlight, look for the “short name” on the [Rouge
wiki](https://github.com/jayferd/rouge/wiki/List-of-supported-languages-and-lexers)
or the [Pygments' Lexers page](http://pygments.org/docs/lexers/).

#### Line numbers

There is a second argument to `highlight` called `linenos` that is optional.
Including the `linenos` argument will force the highlighted code to include line
numbers. For instance, the following code block would include line numbers next
to each line:

{% highlight liquid %}
{% raw %}
{% highlight ruby linenos %}
def foo
  puts 'foo'
end
{% endhighlight %}
{% endraw %}
{% endhighlight %}

#### Stylesheets for syntax highlighting

In order for the highlighting to show up, you’ll need to include a highlighting
stylesheet. For an example stylesheet you can look at
[syntax.css](https://github.com/mojombo/tpw/tree/master/css/syntax.css). These
are the same styles as used by GitHub and you are free to use them for your own
site. If you use `linenos`, you might want to include an additional CSS class
definition for the `.lineno` class in `syntax.css` to distinguish the line
numbers from the highlighted code.

### Post URL

If you would like to include a link to a post on your site, the `post_url` tag
will generate the correct permalink URL for the post you specify.

{% highlight liquid %}
{% raw %}
{% post_url 2010-07-21-name-of-post %}
{% endraw %}
{% endhighlight %}

If you organize your posts in subdirectories, you need to include subdirectory
path to the post:

{% highlight liquid %}
{% raw %}
{% post_url /subdir/2010-07-21-name-of-post %}
{% endraw %}
{% endhighlight %}

There is no need to include the file extension when using the `post_url` tag.

You can also use this tag to create a link to a post in Markdown as follows:

{% highlight liquid %}
{% raw %}
[Name of Link]({% post_url 2010-07-21-name-of-post %})
{% endraw %}
{% endhighlight %}

### Gist

Use the `gist` tag to easily embed a GitHub Gist onto your site. This works
with public or secret gists:

{% highlight liquid %}
{% raw %}
{% gist parkr/931c1c8d465a04042403 %}
{% endraw %}
{% endhighlight %}

You may also optionally specify the filename in the gist to display:

{% highlight liquid %}
{% raw %}
{% gist parkr/931c1c8d465a04042403 jekyll-private-gist.markdown %}
{% endraw %}
{% endhighlight %}

To use the `gist` tag, you'll need to add the
[jekyll-gist](https://github.com/jekyll/jekyll-gist) gem to your project.