jq Cheat Sheet

jq cheat sheet with real commands and snippets for setup, core workflows, debugging, and production-safe automation patterns. If you are working across tools, pair this with the curl Cheat Sheet and JSON Cheat Sheet.

Setup and Installation

Goal: Verify installation and CLI metadata

# Resolve command path from current shell
command -v jq

# Print installed version to confirm runtime
jq --version

# Read top-level help before using subcommands
jq --help

Goal: Install or upgrade the tool on a workstation

# Install package with Homebrew on macOS
brew install jq

# Upgrade to the latest available package
brew upgrade jq

# Re-check version after upgrade
jq --version

Goal: Run day-to-day commands

# Pretty-print JSON response
cat data.json | jq '.'

# Extract nested field values
cat data.json | jq -r '.items[].name'

# Filter array elements by condition
cat data.json | jq '.items[] | select(.enabled == true)'

# Construct new JSON object
cat data.json | jq '{count: (.items|length), names: [.items[].name]}'

Core Workflows

Goal: Capture command help for quick offline lookup

# Create docs folder for generated command references
mkdir -p docs/cli

# Write help output to a timestamped file
jq --help > docs/cli/jq-help.txt

# Search help output for a keyword
rg "config|auth|deploy" docs/cli/jq-help.txt

Goal: Wrap repetitive commands in a script

# Create scripts directory for local automation
mkdir -p scripts

# Write repeatable health-check script
cat > scripts/check-jq.sh <<'SH'
#!/usr/bin/env bash
set -euo pipefail
jq --version
jq --help >/dev/null
SH

# Make script executable and run it
chmod +x scripts/check-jq.sh && ./scripts/check-jq.sh

Configuration and Environment

Goal: Pin environment variables for predictable runs

# Define environment profile for local commands
export JQ_PROFILE=dev

# Persist profile in local shell configuration
echo 'export JQ_PROFILE=dev' >> ~/.zshrc

# Reload shell profile changes
source ~/.zshrc

Automation and CI

Goal: Add tool checks to CI pipeline

# Run lint/test/build in strict mode
set -euo pipefail

# Verify CLI exists before invoking workflow
command -v jq

# Exit quickly if command is unavailable
jq --version

Debugging and Troubleshooting

Goal: Collect diagnostics when commands fail

# Capture command output and exit code
jq --help > /tmp/jq-debug.log 2>&1; echo $?

# Inspect captured diagnostics
tail -n 80 /tmp/jq-debug.log

# Check current shell PATH entries
echo $PATH | tr ':' '\n'

Common Gotchas

• Pin jq versions in CI so local and pipeline behavior match.
• Check tool authentication context before running write or deploy commands.
• Prefer non-interactive flags in scripts to avoid stalled jobs.
• Capture stderr logs in CI artifacts for faster incident triage.
• Keep secrets in environment variables, not committed scripts.

Related Sheets

• curl Cheat Sheet — daily curl commands and production-ready examples.
• JSON Cheat Sheet — daily JSON commands and production-ready examples.
• Nix Cheat Sheet — daily Nix commands and production-ready examples.