Substitutions

Substitutions can be defined in two places:

1. In the frontmatter YAML within a file.
2. Globally for all files in docset.yml

In both cases the yaml to define them is as followed:

subs:
  key: value
  another-var: Another Value

If a substitution is defined globally it may not be redefined (shaded) in a files frontmatter. Doing so will result in a build error.

To use the variables in your files, surround them in curly brackets ({{variable}}).

Here are some variable substitutions:

Substitutions are supported in code blocks but are disabled by default. Enable substitutions by adding subs=true to the code block.

```bash subs=true
# Your code with variables
```

wget https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-7.17.0-linux-x86_64.tar.gz
wget https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-7.17.0-linux-x86_64.tar.gz.sha512
shasum -a 512 -c elasticsearch-7.17.0-linux-x86_64.tar.gz.sha512
tar -xzf elasticsearch-7.17.0-linux-x86_64.tar.gz
cd elasticsearch-7.17.0/

```{code} sh subs=true
wget https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-{{version}}-linux-x86_64.tar.gz
wget https://artifacts.elastic.co/downloads/elasticsearch/elasticsearch-{{version}}-linux-x86_64.tar.gz.sha512
shasum -a 512 -c elasticsearch-{{version}}-linux-x86_64.tar.gz.sha512
tar -xzf elasticsearch-{{version}}-linux-x86_64.tar.gz
cd elasticsearch-{{version}}/
```

echo "This was defined in docset.yml"

```bash subs=true
echo "{{a-global-variable}}"
```

echo "{{a-global-variable}}"

```bash
echo "{{a-global-variable}}"
```