sniff

Reports file properties: detected or assumed encoding, field types, record count, and the CSV delimiter currently in use.

sniff does not auto-detect the CSV delimiter. The CLI default is --delimiter ,. A semicolon-separated file is reported as a single column unless you pass --delimiter ";". Use analyze when you need delimiter auto-detection.

Encoding is often unknown when sniff cannot determine it; pass --encoding to override.

# Report file properties (text output)
undatum sniff data.csv

# Semicolon CSV: pass the delimiter
undatum sniff data.csv --delimiter ";"

# Output as JSON (also --format-out json, or --output ending in .json)
undatum sniff data.jsonl --format json

# Output as YAML
undatum sniff data.csv --format yaml --output sniff.yaml
undatum sniff nested.jsonl --flatten-nested --format json

Key options: --delimiter, --encoding, --format / --format-out (text, json, yaml), --output, --flatten-nested, --table / --sheet. See shared options.