Use ajq with other data formats

ajq’s core input modes stay small on purpose: JSON, NDJSON, raw strings, and null input. When the source data is another format, put a format adapter before ajq and let ajq work on the JSON it emits.

This keeps pure jq-compatible ajq pipelines deterministic while still letting you use the existing jq ecosystem around it. Tools such as jc, yq/xq, and fq are commonly used alongside jq for this kind of conversion.

Convert command output with jc

Use jc when a system command prints text that you want to query as JSON:

df -h | jc --df | ajq -c '.[] | {filesystem, size, used_percent}'

Once jc emits JSON, ajq sees ordinary JSON values. Add semantic filters only when you explicitly want model-backed judgement:

ps aux | jc --ps | ajq --backend mock -c '.[] | select(.command =~ "database server")'

Convert YAML, XML, or TOML with yq and xq

Use yq for YAML or TOML files that should flow into an ajq query:

yq -o=json '.services' docker-compose.yml \
  | ajq -c 'to_entries[] | {name: .key, image: .value.image}'

Some yq distributions also provide xq for XML-to-JSON workflows:

xq '.rss.channel.item' feed.xml \
  | ajq -c '.[] | {title, link}'

Check your installed yq/xq command’s flags, because option names vary by implementation. The important contract is that the adapter writes JSON to stdout before ajq starts.

Convert binary-derived data with fq

Use fq when a binary or structured file format can be projected as JSON. For decoded values, use -V or tovalue when you need fq to write the JSON value instead of its display tree.

fq '.frames[0:10] | map(tobytesrange.start)' file.mp3 \
  | ajq -c '{frame_count: length, first_offset: .[0]}'

Keep the format-specific parsing in fq; keep jq and semantic operations in ajq after the JSON boundary.

Choose the ajq input mode after conversion

Most adapters emit a single JSON value, so the default ajq input mode is enough. If an adapter emits one JSON value per line, ajq processes it as NDJSON:

some-adapter --json-lines input.dat \
  | ajq -c 'select(.level == "error")'

If you only have raw text and do not want a JSON adapter, use ajq raw-input mode instead:

some-command | ajq -R -r 'select(test("error"))'

Related

• Process an NDJSON stream - ajq input framing and raw line mode.
• Input and output modes reference - every input and output flag.