yq/pkg/yqlib/doc/Add.md

Add behaves differently according to the type of the LHS:

• arrays: concatenate
• number scalars: arithmetic addition (soon)
• string scalars: concatenate (soon)

Use += as append assign for things like increment. .a += .x is equivalent to running .a |= . + .x.

Concatenate and assign arrays

Given a sample.yml file of:

a: {val: thing, b: [cat, dog]}
'': null

then

yq eval '.a.b += ["cow"]' sample.yml

will output

a: {val: thing, b: [cat, dog, cow]}
'': null

Concatenate arrays

Given a sample.yml file of:

a: [1, 2]
b: [3, 4]
'': null

then

yq eval '.a + .b' sample.yml

will output

[1, 2, 3, 4]

Concatenate null to array

Given a sample.yml file of:

a: [1, 2]
'': null

then

yq eval '.a + null' sample.yml

will output

[1, 2]

Add object to array

Given a sample.yml file of:

a: [1, 2]
c: {cat: meow}
'': null

then

yq eval '.a + .c' sample.yml

will output

[1, 2, {cat: meow}]

Add string to array

Given a sample.yml file of:

a: [1, 2]
'': null

then

yq eval '.a + "hello"' sample.yml

will output

[1, 2, hello]

Update array (append)

Given a sample.yml file of:

a: [1, 2]
b: [3, 4]
'': null

then

yq eval '.a = .a + .b' sample.yml

will output

a: [1, 2, 3, 4]
b: [3, 4]
'': null