The or and and operators take two parameters and return a boolean result. not flips a boolean from true to false, or vice versa. These are most commonly used with the select operator to filter particular nodes.

OR example

Running

yq eval --null-input 'true or false'

will output

true

AND example

Running

yq eval --null-input 'true and false'

will output

false

Matching nodes with select, equals and or

Given a sample.yml file of:

- a: bird
  b: dog
- a: frog
  b: bird
- a: cat
  b: fly

then

yq eval '[.[] | select(.a == "cat" or .b == "dog")]' sample.yml

will output

- a: bird
  b: dog
- a: cat
  b: fly

Not true is false

Running

yq eval --null-input 'true | not'

will output

false

Not false is true

Running

yq eval --null-input 'false | not'

will output

true

String values considered to be true

Running

yq eval --null-input '"cat" | not'

will output

false

Empty string value considered to be true

Running

yq eval --null-input '"" | not'

will output

false

Numbers are considered to be true

Running

yq eval --null-input '1 | not'

will output

false

Zero is considered to be true

Running

yq eval --null-input '0 | not'

will output

false

Null is considered to be false

Running

yq eval --null-input '~ | not'

will output

true