Adding `cols` library as a dependency

Run this command in a terminal, in your project's directory:

cargo add cols

To add it manually, edit your project's Cargo.toml file and add to the [dependencies] section:

cols = "0.3.2"

The cols library will be automatically available globally.

Back to the crate overview.

Readme

cols

Smart adaptive formatting of columnar data for Rust.

cols is designed for CLI tools that need terminal-aware table output with tree rendering, multiple output formats, and built-in filtering. Think lsblk, lsmem, or pstree.

Documentation | API Reference | Crates.io

Quick start

[dependencies]
cols = "0.2"

use cols::{Table, Column, print_table_to_string};

let mut table = Table::new();
table.add_column(Column::new("NAME").width_fixed(10));
table.add_column(Column::new("SIZE").width_fixed(6).right(true));

let l1 = table.new_line(None);
table.line_mut(l1).data_set(0, "sda").data_set(1, "100G");

let l2 = table.new_line(None);
table.line_mut(l2).data_set(0, "sdb").data_set(1, "50G");

let output = print_table_to_string(&table).unwrap();

NAME         SIZE
sda          100G
sdb           50G

Tree rendering

use cols::{Table, Column, print_table_to_string};

let mut table = Table::new();
table.add_column(Column::new("NAME").tree(true));
table.add_column(Column::new("SIZE").right(true));

let root = table.new_line(None);
table.line_mut(root).data_set(0, "root").data_set(1, "100");

let c1 = table.new_line(Some(root));
table.line_mut(c1).data_set(0, "child1").data_set(1, "50");

let gc = table.new_line(Some(c1));
table.line_mut(gc).data_set(0, "grandchild").data_set(1, "20");

let c2 = table.new_line(Some(root));
table.line_mut(c2).data_set(0, "child2").data_set(1, "30");

NAME           SIZE
root            100
├─child1         50
│ └─grandchild   20
└─child2         30

Multiple output modes

The same table can be rendered in seven formats without rebuilding it:

use cols::OutputMode;

table.output_mode_set(OutputMode::Json);

Normal — human-readable with column alignment and padding. Raw — compact, separator-delimited. Export — NAME="value" pairs. ShellVar — like Export with shell-safe column names. JSON — typed JSON array of objects. CSV — RFC 4180 with automatic quoting. Markdown — pipe-delimited with alignment support.

Features

Adaptive column widths with fixed, fractional, or content-sized hints
Tree rendering with Unicode or ASCII connectors
7 output modes: Normal, Raw, Export, JSON, ShellVar, CSV, Markdown
Group brackets for M:N member/child relationships
Filter expressions with boolean logic, comparisons, regex, and integer suffixes (K/M/G/T)
Sorting with custom comparators
Column alignment: left, center, right (column default with per-cell override)
Streaming mode: output rows incrementally without buffering the whole table
Builder API: Column::new("NAME").width_fixed(10).right(true).truncate(true)

Examples

The examples/ directory contains runnable demos:

cargo run --example ls       # simple file listing
cargo run --example tree     # directory tree
cargo run --example json     # all output modes
cargo run --example filter   # filter expressions
cargo run --example groups   # group bracket rendering
cargo run --example sort     # alphabetic vs numeric sorting
cargo run --example wrap     # column wrapping

License

Licensed under either of Apache License, Version 2.0 or MIT License at your option.

Adding cols library as a dependency

Adding `cols` library as a dependency