$ cd yaml-frontmatter

# The YAML frontmatter is available in the `metadata` Handlebars variable.
$ zk list -q --format "\{{path}}: \{{json metadata}}"
>keywords.md: {"keywords":["writing","essay","practice"]}
>empty.md: {}
>full.md: {"aliases":["Structure of essay","Rewrite"],"colors":{"sky":"blue","sun":"yellow"},"date":"2011-05-16 09:58:57","tags":["writing","essay","practice"],"title":"Improve the structure of essays by rewriting"}
>minimal.md: {"title":"Only one metadata"}
>tag-list.md: {"tags":["writing","essay, practice"],"title":"Tags using a full YAML list"}
>case.md: {"colors":{"sky":"blue","sun":"yellow"},"date":"2011-05-16 09:58:57","tags":["writing","essay","practice"],"title":"Test that keys are normalized to lowercase."}

# Title extracted from the frontmatter.
$ zk list -q --format "\{{path}}: \{{title}}"
>keywords.md: Alias of tags
>empty.md: Empty frontmatter
>full.md: Improve the structure of essays by rewriting
>minimal.md: Only one metadata
>tag-list.md: Tags using a full YAML list
>case.md: Test that keys are normalized to lowercase.

# Tags extracted from the frontmatter.
$ zk list -q --format "\{{path}}: \{{json tags}}"
>keywords.md: ["writing","essay","practice"]
>empty.md: []
>full.md: ["writing","essay","practice"]
>minimal.md: []
>tag-list.md: ["writing","essay, practice"]
>case.md: ["writing","essay","practice"]

# Creation date extracted from the frontmatter.
$ zk list -q --format "\{{path}}: \{{format-date created 'full'}}"
>keywords.md: {{match '.*'}}
>empty.md: {{match '.*'}}
>full.md: Monday, May 16, 2011
>minimal.md: {{match '.*'}}
>tag-list.md: {{match '.*'}}
>case.md: Monday, May 16, 2011

# `--mention` uses the aliases from the frontmatter.
$ zk list -q --format "\{{path}}: \{{json snippets}}" --mention full.md
>minimal.md: ["Here's a mention of rewriting."]
>empty.md: ["This is a mention of structure of essay."]

$ zk list -q --format "\{{path}}: \{{json snippets}}" --mentioned-by minimal.md
>full.md: ["Here's a mention of rewriting."]

$ zk list -q --format "\{{path}}: \{{json snippets}}" --mentioned-by empty.md
>full.md: ["This is a mention of structure of essay."]