Dtcat

dtcat — Tabular Data File Viewer

View and analyze tabular data files at the command line. Supports CSV, TSV, Parquet, Arrow/Feather, JSON, NDJSON, and Excel. Outputs structured, LLM-friendly markdown.

Quick Reference

# Auto-detect format and show overview
dtcat data.csv
dtcat data.parquet
dtcat data.arrow
dtcat data.json
dtcat report.xlsx

# Column names and types only
dtcat data.parquet --schema

# Summary statistics per column
dtcat data.csv --describe

# File metadata (size, format, shape, sheets)
dtcat report.xlsx --info

# View a specific sheet (Excel only)
dtcat report.xlsx --sheet Revenue

# First/last N rows
dtcat data.csv --head 10
dtcat data.csv --tail 10

# Show all rows (override adaptive limit)
dtcat data.csv --all

# Random sample of rows
dtcat huge.parquet --sample 20
dtcat huge.parquet --sample 50 --csv

# Raw CSV output for piping
dtcat data.parquet --csv

# Convert between formats
dtcat data.csv --convert parquet -o data.parquet
dtcat report.xlsx --sheet Revenue --convert csv -o revenue.csv
dtcat data.parquet --convert ndjson              # text formats go to stdout

# Override format detection
dtcat data.txt --format csv

# Skip metadata rows above header
dtcat data.csv --skip 2

Supported Formats

| Format | Extensions | Auto-detected | |--------|-----------|---------------| | CSV | .csv | Yes (magic + extension) | | TSV | .tsv, .tab | Yes | | Parquet | .parquet, .pq | Yes (PAR1 magic) | | Arrow/Feather | .arrow, .feather, .ipc | Yes (ARROW1 magic) | | JSON | .json | Yes ([ prefix) | | NDJSON | .ndjson, .jsonl | Yes ({ prefix) | | Excel | .xlsx, .xls, .xlsb, .ods | Yes (PK/OLE magic) |

Detection priority: --format flag > magic bytes > file extension.

Default Behavior

• 50 rows: shows first 25 + last 25 rows
• Excel, multiple sheets: lists all sheets with schemas (use --sheet to pick one)

Flags

| Flag | Purpose | |------|---------| | --format | Override format detection (csv, tsv, parquet, arrow, json, ndjson, excel) | | --sheet | Select sheet by name or 0-based index (Excel only) | | --skip | Skip first N rows before header | | --schema | Column names and types only | | --describe | Summary statistics (count, mean, std, min, max, median, unique) | | --head | First N rows | | --tail | Last N rows | | --all | Show all rows (override adaptive limit) | | --sample | Randomly sample N rows | | --csv | Output as CSV instead of markdown | | --info | File metadata (size, format, shape, sheets) | | --convert | Convert to format (csv, tsv, parquet, arrow, json, ndjson) | | -o | Output file path (required for binary formats with --convert) |

Exit Codes

| Code | Meaning | |------|---------| | 0 | Success | | 1 | Runtime error (file not found, corrupt) | | 2 | Invalid arguments |

Workflow

1. Run dtcat to see the overview (schema + sample data)
2. For Excel multi-sheet files, pick a sheet with --sheet
3. Use --describe for statistical analysis
4. Use --head/--tail to zoom into specific regions, --sample for random rows
5. Use --csv when you need to pipe data to other tools
6. Use --convert to transform between formats (e.g., CSV to Parquet)

Mutual Exclusivity

• --schema, --describe, --info, --csv, --convert are mutually exclusive with each other
• --sample is mutually exclusive with --head, --tail, --all
• --convert is mutually exclusive with all display flags

Source & license

This open-source skill is cataloged on AgentStack and links to its original source — we do not rehost the code.

• Author: LouLouLibs
• Source: LouLouLibs/claude-skills
• License: MIT

Install and usage instructions live in the source repository linked above.