Convert CSV to JSON Lines using Miller

Transforms tabular CSV data into newline-delimited JSON (JSONL) for easy ingestion into document databases or log analyzers.

$ mlr --icsv --ojsonl cat data.csv

1. [01] mlrmlr
   Invokes Miller, a command-line tool for processing structured data formats.
2. [02] mlr--icsv
   Sets the input format to CSV, assuming the first row contains column headers.
3. [03] mlr--ojsonl
   Sets the output format to JSON Lines (NDJSON), where each record is a separate JSON object on a new line.
4. [04] mlrcat
   The Miller verb that passes input records directly to the output without modification.
5. [05] mlrdata.csv
   The target input file to be processed.

{"id": 1, "name": "Alice", "role": "Admin"}
{"id": 2, "name": "Bob", "role": "User"}
{"id": 3, "name": "Charlie", "role": "User"}
{"id": 4, "name": "Diana", "role": "Guest"}

• Footgun: If your CSV lacks a header row, Miller will treat the first data row as headers unless you pass the --implicit-csv-header flag.
• Cost/Permission: Runs entirely locally, requiring read permissions on the input file. Processing extremely large files is memory-efficient as Miller streams the data.