yq/mkdocs/write.md

yq w <yaml_file> <path_expression> <new value>

Updates all the matching nodes of path expression to the supplied value.

See docs for path expression for more details.

Basic

Given a sample.yaml file of:

b:
  c: 2

then

yq w sample.yaml b.c cat

will output:

b:
  c: cat

Updating files in-place

yq w -i sample.yaml b.c cat

will update the sample.yaml file so that the value of 'c' is cat.

From STDIN

cat sample.yaml | yq w - b.c blah

Adding new fields

Any missing fields in the path will be created on the fly.

Given a sample.yaml file of:

b:
  c: 2

then

yq w sample.yaml b.d[+] "new thing"

will output:

b:
  c: cat
  d:
    - new thing

Appending value to an array field

Given a sample.yaml file of:

b:
  c: 2
  d:
    - new thing
    - foo thing

then

yq w sample.yaml "b.d[+]" "bar thing"

will output:

b:
  c: cat
  d:
    - new thing
    - foo thing
    - bar thing

Note that the path is in quotes to avoid the square brackets being interpreted by your shell.

Multiple Documents

Update a single document

Given a sample.yaml file of:

something: else
---
b:
  c: 2

then

yq w -d1 sample.yaml b.c 5

will output:

something: else
---
b:
  c: 5

Update all documents

Given a sample.yaml file of:

something: else
---
b:
  c: 2

then

yq w -d'*' sample.yaml b.c 5

will output:

something: else
b:
  c: 5
---
b:
  c: 5

UPDATE THIS UPDATE THIS INCLUDE DELETE EXAMPLE

Updating multiple values with a script

Given a sample.yaml file of:

b:
  c: 2
  e:
    - name: Billy Bob

and a script update_instructions.yaml of:

b.c: 3
b.e[+].name: Howdy Partner

then

yq w -s update_instructions.yaml sample.yaml

will output:

b:
  c: 3
  e:
    - name: Howdy Partner

And, of course, you can pipe the instructions in using '-':

cat update_instructions.yaml | yq w -s - sample.yaml