web/_posts/2019-08-08-write-a-new-post.md

---
title: Writing a New Post
author: Cotes Chung
date: 2019-08-08 14:10:00 +0800
categories: [Blogging, Tutorial]
tags: [writing]
---

## Naming and Path

Create a new file named `YYYY-MM-DD-TITLE.EXTENSION` and put it in the `_post/` of the root directory. Please note that the `EXTENSION` must be one of `md` and `markdown`. From `v2.4.1`, you can create sub-directories under `_posts/` to categorize posts.

## Front Matter

Basically, you need to fill the [Front Matter](https://jekyllrb.com/docs/front-matter/) as below at the top of the post:

```yaml
---
title: TITLE
date: YYYY-MM-DD HH:MM:SS +/-TTTT
categories: [TOP_CATEGORIE, SUB_CATEGORIE]
tags: [TAG]     # TAG names should always be lowercase
---
```

> **Note**: The posts' ***layout*** has been set to `post` by default, so there is no need to add the variable ***layout*** in Front Matter block.

### Timezone of date

In order to accurately record the release date of a post, you should not only setup the `timezone` of `_config.yml` but also provide the the post's timezone in field `date` of its Front Matter block. Format: `+/-TTTT`, e.g. `+0800`.

### Categories and Tags

The `categories` of each post is designed to contain up to two elements, and the number of elements in `tags` can be zero to infinity.

The list of posts belonging to the same *category*/*tag* is recorded on a separate page. At the same time, the number of these *category*/*tag* type pages is equal to the number of `categories` / `tags` elements for all posts, which means that the two number must be exactly the same.

For instance, let's say there is a post with front matter:

```yaml
categories: [Animal, Insect]
tags: bee
```

Then we should have two *category* type pages placed in folder `categories` of root and one *tag* type page placed in folder `tags`  of root:

```sh
.
├── categories
│   ├── animal.html         # a category type page
│   └── insect.html
├── tags
│   └── bee.html            # a tag type page
...
```
    
and the content of a *category* type page is

```yaml
---
layout: category
title: CATEGORY_NAME        # e.g. Insect
category: CATEGORY_NAME     # e.g. Insect
---
```

the content of a *tag* type page is

```yaml
---
layout: tag
title: TAG_NAME             # e.g. bee
tag: TAG_NAME               # e.g. bee
---
```

With the increasing number of posts, the number of categories and tags will increase several times!  If we still manually create these *category*/*tag* type files, it will obviously be a super time-consuming job, and it is very likely to miss some of them, i.e., when you click on the missing `category` or `tag` link from a post or somewhere, the browser will complain to you "404 Not Found". The good news is we got a lovely script tool `_scripts/sh/create_pages.sh` to finish the boring tasks. Basically we will use it through `run.sh`, `build.sh` or `deploy.sh` that placed in `tools/` instead of running it separately. Check out its use case [here]({{ "/posts/getting-started/#deployment" | relative_url }}).

## Last modified date

The last modified date of a post is obtained according to the post's latest git commit date, and the modified date of all posts are designed to be stored in the file `_data/updates.yml`. Then contents of that file may be as follows:

```yaml
-
  filename: getting-started             # the post filename without date and extension
  lastmod: 2020-04-13 00:38:56 +0800    # the post last modified date
-
  ... 
```

You can choose to create this file manually, But the better approach is to let it be automatically generated by a script tool, and `_scripts/sh/dump_lastmod.sh` was born for this! Similar to the other script (`create_pages.sh`) mentioned above, it is also be called from the other superior tools, so it doesn't have to be used separately.

When some posts have been modified since their published date and also the file `_data/updates.yml` was created correctly, a list with the label **Recent Updates** will be displayed in the right panel of the desktop view, which records the five most recently modified posts.

## Table of Contents

By default, the **T**able **o**f **C**ontents (TOC) is displayed on the right panel of the post. If you want to turn it off globally, go to `_config.yml` and set the value of variable `toc` to `false`. If you want to turn off TOC for specific post, add the following to post's [Front Matter](https://jekyllrb.com/docs/front-matter/):

```yaml
---
toc: false
---
```


## Comments

Similar to TOC, the [Disqus](https://disqus.com/) comments is loaded by default in each post, and the global switch is defined by variable `comments` in file `_config.yml` . If you want to close the comment for specific post, add the following to the **Front Matter** of the post:

```yaml
---
comments: false
---
```


## Mathematics

For website performance reasons, the mathematical feature won't be loaded by default. But it can be enabled by:

```yaml
---
math: true
---
```

## Preview Image

If you want to add an image to the top of the post contents, specify the url for the image by:

```yaml
---
image: /path/to/image-file
---
```

## Pinned Posts

You can pin one or more posts to the top of the home page, and the fixed posts are sorted in reverse order according to their release date. Enable by:

```yaml
---
pin: true
---
```

## Code Block

Markdown symbols <code class="highlighter-rouge">```</code> can easily create a code block as following examples.

```
This is a common code snippet, without syntax highlight and line number.
```

## Specific Language

Using <code class="highlighter-rouge">```language</code> you will get code snippets with line numbers and syntax highlight.

> **Note**: The Jekyll style `{% raw %}{%{% endraw %} highlight LANGUAGE {% raw %}%}{% endraw %}` or `{% raw %}{%{% endraw %} highlight LANGUAGE linenos {% raw %}%}{% endraw %}` are not allowed to be used in this theme !

```yaml
# Yaml code snippet
items:
    - part_no:   A4786
      descrip:   Water Bucket (Filled)
      price:     1.47
      quantity:  4
```

#### Liquid Codes

If you want to display the **Liquid** snippet, surround the liquid code with `{% raw %}{%{% endraw %} raw {%raw%}%}{%endraw%}` and `{% raw %}{%{% endraw %} endraw {%raw%}%}{%endraw%}` .

{% raw %}
```liquid
{% if product.title contains 'Pack' %}
  This product's title contains the word Pack.
{% endif %}
```
{% endraw %}


## Learn More

For more knowledge about Jekyll posts, visit the [Jekyll Docs: Posts](https://jekyllrb.com/docs/posts/).