yq¶

--- Reading ---

To read a specific key from a YAML file:

yq '.<key>' <file>.yaml

To read a nested key

yq '.parent.child' <file>.yaml

To read an array element by index

yq '.list[0]' <file>.yaml

To read all array elements

yq '.list[]' <file>.yaml

To read multiple keys

yq '.foo, .bar' <file>.yaml

--- Writing ---

To set a key value in-place:

yq -i '.<key> = "<value>"' <file>.yaml

To set a nested key in-place

yq -i '.parent.child = "<value>"' <file>.yaml

To append to an array in-place

yq -i '.list += ["<value>"]' <file>.yaml

To delete a key in-place

yq -i 'del(.<key>)' <file>.yaml

--- Filtering ---

To filter out null or empty values:

yq '.foo | select(length > 0)' <file>.yaml

To select array items matching a condition

yq '.list[] | select(.name == "<value>")' <file>.yaml

To sort all keys alphabetically

yq -i 'sort_keys(.)' <file>.yaml

--- Format Conversion ---

To convert YAML to JSON:

yq -o=json <file>.yaml

To convert JSON to YAML

yq -p=json -o=yaml <file>.json

To convert YAML to TOML

yq -o=toml <file>.yaml

--- Merging ---

To merge two YAML files (second overrides first):

yq '. * load("<other>.yaml")' <file>.yaml

--- Markdown Front Matter ---

To read a front matter key from a Markdown file:

yq --front-matter="extract" '.<key>' <file>.md

To set a front matter key in a Markdown file

yq --front-matter="process" -i '.<key> = "<value>"' <file>.md