LinuxCommandLibrary

yq

Lightweight YAML and JSON processor

TLDR

Read a value from a YAML file
$ yq '.[key]' [file.yaml]
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Read a nested value
$ yq '.[parent].[child]' [file.yaml]
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Convert YAML to JSON
$ yq -o=json [file.yaml]
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Convert JSON to YAML
$ yq -p=json [file.json]
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Edit a file in place
$ yq -i '.[key] = "value"' [file.yaml]
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Merge multiple YAML files
$ yq eval-all 'select(fileIndex == 0) * select(fileIndex == 1)' [file1.yaml] [file2.yaml]
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Select items from an array
$ yq '.items[] | select(.name == "foo")' [file.yaml]
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Count array elements
$ yq '.items | length' [file.yaml]
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SYNOPSIS

yq [options] expression [file ...]

DESCRIPTION

yq is a lightweight command-line YAML, JSON, XML, CSV, TOML, and properties processor. It uses jq-like syntax for querying and manipulating structured data, making it easy to extract values, modify documents, and convert between formats.
The tool supports reading from files or stdin, and can output to stdout or edit files in place. Expressions follow a path-based syntax similar to jq, allowing complex queries and transformations.
Two implementations exist: mikefarah/yq (Go-based, standalone binary) and kislyuk/yq (Python wrapper around jq). The Go version is more commonly installed via package managers.

PARAMETERS

-i, --inplace

Edit files in place.
-p, --input-format format
Input format: yaml, json, xml, props, csv, tsv, toml.
-o, --output-format format
Output format: yaml, json, xml, props, csv, tsv.
-I, --indent n
Set indentation level (default 2).
-C, --colors
Force colored output.
-M, --no-colors
Disable colored output.
-N, --no-doc
Don't print document separators.
-e, --exit-status
Set exit status based on expression result.
--from-file file
Load expression from a file.
-n, --null-input
Don't read input; useful for creating new documents.
-s, --split-exp expression
Split output into multiple files.
-v, --verbose
Enable verbose output.
-h, --help
Display help message.
-V, --version
Display version information.

CAVEATS

The two yq implementations have different syntax and capabilities. The Go version (mikefarah/yq) uses its own expression language, while the Python version (kislyuk/yq) uses jq syntax directly. Check which version is installed with yq --version.

HISTORY

The Python yq wrapper was created by Andrey Kislyuk and released in 2017 as a thin jq wrapper for YAML. The Go-based yq was created by Mike Farah around the same time as a standalone tool. The Go version has become more popular due to being a single binary with no dependencies and supporting multiple formats beyond YAML.

SEE ALSO

jq(1), xmlstarlet(1), dasel(1), fx(1)

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