headers

Extracts field names from data files (CSV, JSON Lines, BSON, XML, Excel, and other iterabledata sources).

Default scan --limit is 10000. --format-out json (or --output ending in .json) writes JSON instead of text.

undatum headers data.jsonl
undatum headers data.csv --limit 50000
undatum headers data.csv --format-out json --output fields.json
undatum headers workbook.xlsx --table Sheet2

Key options: --limit (default 10000), --format-out, --output, --zipfile, --table / --sheet. See shared options.