Quickly Find Undefined or Null YAML Keys with YQ

When doing maintenance for this static generated website I found myself in a situation where I wanted to find a YAML (YAML Ain’t Markup Language) key within the front matter of all published Markdown based posts that is undefined or has a value of null. In my experience I’ve found this easier to achieve using a software program that is designed to process structured data like YAML. Therefore, I decided to use the program called “yq”. Since there will be multiple files the output needs to display the length of the key value but also the associated filename. It took a little effort to figure it out plus the use of “find” and “grep”, but I was able to form a series of commands that would achieve exactly what I was looking for. Come along to learn how to achieve this without the trial and error I went through. Assumptions General understanding of using a GNU/Linux or Unix terminal (command-line interface) Steps prefixed with a “$” (dollar sign) represents the CLI (command-line interface)…