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mlr — Miller is like `awk`, `sed`, `cut`, `join`, and `sort` for name-indexed data such as CSV, TSV, and t

Submitted by: @import:tldr-pages·Mar 2, 2026·

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Problem

How to use the mlr command: Miller is like awk, sed, cut, join, and sort for name-indexed data such as CSV, TSV, and tabular JSON. More information: <https://miller.readthedocs.io/en/latest/manpage/>.

Solution

mlr — Miller is like awk, sed, cut, join, and sort for name-indexed data such as CSV, TSV, and tabular JSON. More information: <https://miller.readthedocs.io/en/latest/manpage/>.

Pretty-print a CSV file in a tabular format:

mlr --icsv --opprint cat {{example.csv}}

Receive JSON data and pretty print the output:

{{echo '{"key":"value"}'}} | mlr --ijson --opprint cat

Sort alphabetically on a field:

mlr --icsv --opprint sort -f {{field}} {{example.csv}}

Sort in descending numerical order on a field:

mlr --icsv --opprint sort -nr {{field}} {{example.csv}}

Convert CSV to JSON, performing calculations, and display those calculations:

mlr --icsv --ojson put '${{newField1}} = ${{oldFieldA}}/${{oldFieldB}}' {{example.csv}}

Receive JSON and format the output as vertical JSON:

{{echo '{"key1":"value1", "key2":"value2"}'}} | mlr --ijson --ojson --jvstack cat

Filter lines of a compressed CSV file treating numbers as [S]trings:

mlr --prepipe 'gunzip' {{[-c|--csv]}} filter {{[-S|--infer-none]}} '${{fieldName}} =~ "{{regex}}"' {{example.csv.gz}}

Code Snippets

Pretty-print a CSV file in a tabular format

mlr --icsv --opprint cat {{example.csv}}

Receive JSON data and pretty print the output

{{echo '{"key":"value"}'}} | mlr --ijson --opprint cat

Sort alphabetically on a field

mlr --icsv --opprint sort -f {{field}} {{example.csv}}

Sort in descending numerical order on a field

mlr --icsv --opprint sort -nr {{field}} {{example.csv}}

Convert CSV to JSON, performing calculations, and display those calculations

mlr --icsv --ojson put '${{newField1}} = ${{oldFieldA}}/${{oldFieldB}}' {{example.csv}}

Context

tldr-pages: common/mlr

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