This creates an array using the expression between the square brackets.

Collect empty

Running

yq eval --null-input '[]'

will output

[]

Collect single

Running

yq eval --null-input '["cat"]'

will output

- cat

Collect many

Given a sample.yml file of:

a: cat
b: dog

then

yq eval '[.a, .b]' sample.yml

will output

- cat
- dog