Tinkering with YQ, it's like JQ but for YAML rather than JSON

 A colleague was tinkering with Mike Farah's excellent yq tool, and had asked about updating it on his Mac.

I've got yq installed via Homebrew: -

brew update

which threw up: -

Error: 

  homebrew-core is a shallow clone.

To `brew update`, first run:

  git -C /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core fetch --unshallow

so I did this: -

git -C /usr/local/Homebrew/Library/Taps/homebrew/homebrew-core fetch --unshallow

and then: -

brew upgrade yq

which resulted in the latest version: -

yq --version

yq version 4.5.1

Subsequently, my friend was then looking to use the evaluate feature of yq to run queries against YAML documents, with the query string being defined in an environment variable.

Therefore, I had to try this ...

Firstly, I created sample.yaml 

name:

 - Ben

 - Dave

 - Tom

 - Jerry

which yq correctly evaluates: -

yq eval sample.yaml

name:

  - Ben

  - Dave

  - Tom

  - Jerry

and: -

yq eval .name sample.yaml

- Ben

- Dave

- Tom

- Jerry

I then set the environment variable to define my search query: -

export FRIEND="Ben"

and updated my yq query: -

yq eval ".name = \"$FRIEND\"" sample.yaml

name: Ben

and then changed my variable: -

export FRIEND="Tom"

and re-ran my query: -

yq eval ".name = \"$FRIEND\"" sample.yaml

name: Tom

Thanks to this: -

how to pass environment variable as value #468

yq: evaluate

https://mikefarah.gitbook.io/yq/commands/evaluate