jfm

jfm is a tool for interacting with Jekyll frontmatter from the command line.

In Jekyll, all posts have “frontmatter” at the start of them, that define certain things about the post:

---
layout: post
title: A lovely post
---

Here’s a lovely post

The frontmatter is the bit between the --- and the ---.

This tool allows you to search for posts based on their frontmatter, and then manipulate that frontmatter in certain ways. Basically, it makes doing find-and-replace on Jekyll frontmatter a lot easier.

$ gem install jfm

jfm offers two commands: find and edit.

find finds posts that match the given queries. For example, given a site with only the example post given above, you could find that post in the following ways:

$ jfm find "layout"
_posts/2020-12-02-lovely-post.markdown

$ jfm find "layout: post"
_posts/2020-12-02-lovely-post.markdown

$ jfm find "layout: ~page"
_posts/2020-12-02-lovely-post.markdown

$ jfm find "title: A lovely post"
_posts/2020-12-02-lovely-post.markdown

$ jfm find "title: A lovely post" "layout: post"
_posts/2020-12-02-lovely-post.markdown

In short:

• a query of foo will match posts that have a variable called foo regardless of its value
• a query of foo: bar will match posts that have a variable called foo set to the value bar
• a query of foo: ~bar will match posts that have a variable called foo that is set to any value other than bar
• you can pass multiple queries; find will return posts that match them all

edit edits the frontmatter to set a given value. For example, to set the layout of every single post to “page”, you could:

$ ls _posts/* | jfm edit "layout: page"

This pairs well with the find command to only edit certain posts:

$ jfm find "layout: post" | jfm edit "layout: page"

If a variable with that name already exists, it will be replaced; if it doesn’t exist, it will be created.

After checking out the repo, run bin/setup to install dependencies. Then, run rake spec to run the tests. You can also run bin/console for an interactive prompt that will allow you to experiment.

To install this gem onto your local machine, run bundle exec rake install. To release a new version, update the version number in version.rb, and then run bundle exec rake release, which will create a git tag for the version, push git commits and tags, and push the .gem file to rubygems.org.

Bug reports and pull requests are welcome on GitHub at https://github.com/[USERNAME]/jfm. This project is intended to be a safe, welcoming space for collaboration, and contributors are expected to adhere to the code of conduct.

The gem is available as open source under the terms of the MIT License.

Everyone interacting in the Jfm project's codebases, issue trackers, chat rooms and mailing lists is expected to follow the code of conduct.