Yq - Command-Line YAML Processor - tools Cheatsheets

Yq is a lightweight and portable command-line YAML processor. It allows you to query, edit, and manipulate YAML files with ease, similar to how `jq` works for JSON. This tool is invaluable for developers and DevOps engineers working with configuration files, especially in environments like Kubernetes.

Core Yq Commands and Usage

Below are common `yq` commands demonstrating its versatility. Note that some commands might be specific to older versions (v3) and newer versions (v4) might have slightly different syntax or commands.

Reading and Querying YAML

# Read spec.template node from example.yml
yq r example.yml spec.template

# Read from stdin
cat sample.yaml | yq r - b.c

# Print the path of matching elements
yq r --printMode p "a.thing*.*"

# Print the path and value of matching elements
yq r --printMode pv "a.thing*.*"

# Get the length of a list
yq r sample.yml --length animals

# Read with conditions (e.g., filter by name)
yq r sample.yml spec.metadata[name==myapp]

# Collect results into an array
yq r sample.yaml --collect a.*.animal

# Read from a specific document in a multi-document YAML file
yq r -d1 sample.yaml b.c

Validating and Comparing YAML

# Validate a YAML document
yq v valid.yaml

# Compare two YAML documents
yq compare data1.yaml data2.yaml

Writing and Modifying YAML

# Write a value to a specific path
yq w sample.yaml b.c cat

# Delete a node in place from a YAML file
yq d -i sample.yaml b.c

# Merge documents
yq merge data1.yaml data2.yaml

Advanced YAML Processing with `yq e` (Expression Mode)

# Select a specific field from a YAML file
yq e '.path.to.field' file.yaml

# Select a specific field and output in JSON format
yq e -o=json '.path.to.field' file.yaml

# Update a field's value in a YAML file (in-place)
yq e '.path.to.field = "new value"' file.yaml -i

# Delete a field from a YAML file (in-place)
yq e 'del(.path.to.field)' file.yaml -i

# Merge two YAML files using expressions
yq eval-all 'select(fileIndex == 0) * select(fileIndex == 1)' file1.yaml file2.yaml

# Convert YAML to JSON
yq e -o=json '.' file.yaml

# Convert JSON to YAML
yq e -o=yaml '.' file.json

# Transpose YAML into environment variables format
yq e -o=props . file.yaml | sed 's/\'/\\\'/' | envsubst

# Display the structure of the YAML file (keys only)
yq e 'keys' file.yaml

# Use multi-document processing to apply a filter to each document separately
yq ea '.[] | .key' file.yaml

# Checking the existence of a key in a YAML file
yq e 'has("key")' file.yaml

Shell Completion

# Generate shell completion scripts
yq shell-completion

Yq - Command-Line YAML Processor