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convert-file

convert-file

github.com/duckdbData & databases613797 installsUpdated 28w ago
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About convert-file

A skill that guides DuckDB-based conversion of data files between supported formats. It resolves input and output paths, chooses format-specific options, runs the conversion, and reports the result.

Key features

  1. 01Resolve input and output paths
  2. 02Infer format from the output extension
  3. 03Support tabular, JSON, and spatial formats
  4. 04Handle remote inputs and extensions
  5. 05Apply partitioning or compression options

Use cases

  1. 01Convert a CSV file to Parquet
  2. 02Export data as JSONL or TSV
  3. 03Convert spatial files such as GeoJSON
  4. 04Partition or compress a conversion output

Install

Copy the command and run it in a terminal.

$npx skills add https://github.com/duckdb/duckdb-skills --skill convert-file

After installing, type/convert-filein Claude Code to confirm it loaded.

Details

From the project README

You are helping the user convert a data file from one format to another using DuckDB.

Input file: $0 Output file: ${1:-}

Step 1 — Resolve input and output

Input: $0. If it's a bare filename (no /), resolve to a full path with find "$PWD" -name "$0" -not -path '*/.git/*' 2>/dev/null | head -1.

Output: If $1 is provided, use it as the output path. If not, default to the same stem as the input with a .parquet extension (e.g., data.csv → data.parquet).

Infer the output format from the output file extension:

ExtensionFormat clause
.parquet, .pq(default, no clause needed)
.csv(FORMAT csv, HEADER)
.tsv(FORMAT csv, HEADER, DELIMITER '\t')
.json(FORMAT json, ARRAY true)
.jsonl, .ndjson(FORMAT json, ARRAY false)
.xlsx(FORMAT xlsx) — requires INSTALL excel; LOAD excel;
.geojson(FORMAT GDAL, DRIVER 'GeoJSON') — requires LOAD spatial;
.gpkg(FORMAT GDAL, DRIVER 'GPKG') — requires LOAD spatial;
.shp(FORMAT GDAL, DRIVER 'ESRI Shapefile') — requires LOAD spatial;

Step 2 — Convert

Run a single DuckDB command. Prepend extension loads as needed based on both the input and output formats.

duckdb -c "
<EXTENSION_LOADS>
COPY (FROM '<INPUT_PATH>') TO '<OUTPUT_PATH>' <FORMAT_CLAUSE>;
"

For remote inputs (s3://, https://, etc.), prepend the same protocol setup as read-file:

ProtocolPrepend
s3://LOAD httpfs; CREATE SECRET (TYPE S3, PROVIDER credential_chain);
gs:// / gcs://LOAD httpfs; CREATE SECRET (TYPE GCS, PROVIDER credential_chain);
https:// / http://LOAD httpfs;

If the user mentions partitioning (e.g., "partition by year"), add PARTITION_BY (col) to the format clause. This only works with Parquet and CSV output.

If the user mentions compression (e.g., "use zstd"), add CODEC 'zstd' for Parquet output.

Step 3 — Report

On success, report:

  • Input file and detected format
  • Output file, format, and size (ls -lh)
  • Row count if quick to compute

On failure:

  • duckdb: command not found → delegate to /duckdb-skills:install-duckdb
  • Missing extension → install it and retry
  • Input parse error → suggest the user check the input format or try /duckdb-skills:read-file first to inspect it

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