npm package: @stdlib/process-read-stdin
Description: Read data from stdin.
Author: The Stdlib Authors
Latest version: 0.2.3

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<details>
  <summary>
    About stdlib...
  </summary>
  <p>We believe in a future in which the web is a preferred environment for numerical computation. To help realize this future, we've built stdlib. stdlib is a standard library, with an emphasis on numerical and scientific computation, written in JavaScript (and C) for execution in browsers and in Node.js.</p>
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</details>

# stdin

[![NPM version][npm-image]][npm-url] [![Build Status][test-image]][test-url] [![Coverage Status][coverage-image]][coverage-url] <!-- [![dependencies][dependencies-image]][dependencies-url] -->

> Read data from [`stdin`][@stdlib/streams/node/stdin].

<section class="installation">

## Installation

```bash
npm install @stdlib/process-read-stdin
```

</section>

<section class="usage">

## Usage

```javascript
var stdin = require( '@stdlib/process-read-stdin' );
```

#### stdin( \[encoding,] clbk )

Reads data from [`stdin`][@stdlib/streams/node/stdin].

<!-- run-disable -->

```javascript
function onRead( error, data ) {
    if ( error ) {
        return console.error( 'Error: %s', error.message );
    }
    console.log( data.toString() );
    // => '...'
}

stdin( onRead );
```

By default, returned `data` is a [`Buffer`][buffer]. To return a `string` of a specified encoding, provide an `encoding` parameter.

<!-- run-disable -->

```javascript
function onRead( error, data ) {
    if ( error ) {
        return console.error( 'Error: %s', error.message );
    }
    console.log( data );
    // => '...'
}

stdin( 'utf8', onRead );
```

When a file's calling Node.js process is running in a [TTY][tty] context (i.e., no [`stdin`][@stdlib/streams/node/stdin]), `data` will either be an empty [`Buffer`][buffer] (no encoding provided) or an empty `string` (encoding provided).

<!-- run-disable -->

```javascript
var stream = require( '@stdlib/streams-node-stdin' );

function onRead( error, data ) {
    if ( error ) {
        return console.error( 'Error: %s', error.message );
    }
    console.log( data );
    // => ''
}

stream.isTTY = true;

stdin( 'utf8', onRead );
```

</section>

<!-- /.usage -->

<section class="examples">

## Examples

<!-- run-disable -->

<!-- eslint no-undef: "error" -->

```javascript
var string2buffer = require( '@stdlib/buffer-from-string' );
var stream = require( '@stdlib/streams-node-stdin' );
var stdin = require( '@stdlib/process-read-stdin' );

function onRead( error, data ) {
    if ( error ) {
        console.error( 'Error: %s', error.message );
    } else {
        console.log( data.toString() );
        // => 'beep boop'
    }
}

// Fake not being in a terminal context:
stream.isTTY = false;

// Provide a callback to consume all data from `stdin`:
stdin( onRead );

// Push some data to `stdin`:
stream.push( string2buffer( 'beep' ) );
stream.push( string2buffer( ' ' ) );
stream.push( string2buffer( 'boop' ) );

// End the stream:
stream.push( null );
```

</section>

<!-- /.examples -->

<!-- Section for related `stdlib` packages. Do not manually edit this section, as it is automatically populated. -->

<section class="related">

</section>

<!-- /.related -->

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<section class="main-repo" >

* * *

## Notice

This package is part of [stdlib][stdlib], a standard library for JavaScript and Node.js, with an emphasis on numerical and scientific computing. The library provides a collection of robust, high performance libraries for mathematics, statistics, streams, utilities, and more.

For more information on the project, filing bug reports and feature requests, and guidance on how to develop [stdlib][stdlib], see the main project [repository][stdlib].

#### Community

[![Chat][chat-image]][chat-url]

---

## License

See [LICENSE][stdlib-license].


## Copyright

Copyright &copy; 2016-2026. The Stdlib [Authors][stdlib-authors].

</section>

<!-- /.stdlib -->

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<section class="links">

[npm-image]: http://img.shields.io/npm/v/@stdlib/process-read-stdin.svg
[npm-url]: https://npmjs.org/package/@stdlib/process-read-stdin

[test-image]: https://github.com/stdlib-js/process-read-stdin/actions/workflows/test.yml/badge.svg?branch=v0.2.3
[test-url]: https://github.com/stdlib-js/process-read-stdin/actions/workflows/test.yml?query=branch:v0.2.3

[coverage-image]: https://img.shields.io/codecov/c/github/stdlib-js/process-read-stdin/main.svg
[coverage-url]: https://codecov.io/github/stdlib-js/process-read-stdin?branch=main

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[stdlib]: https://github.com/stdlib-js/stdlib

[stdlib-authors]: https://github.com/stdlib-js/stdlib/graphs/contributors

[umd]: https://github.com/umdjs/umd
[es-module]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Modules

[deno-url]: https://github.com/stdlib-js/process-read-stdin/tree/deno
[deno-readme]: https://github.com/stdlib-js/process-read-stdin/blob/deno/README.md
[umd-url]: https://github.com/stdlib-js/process-read-stdin/tree/umd
[umd-readme]: https://github.com/stdlib-js/process-read-stdin/blob/umd/README.md
[esm-url]: https://github.com/stdlib-js/process-read-stdin/tree/esm
[esm-readme]: https://github.com/stdlib-js/process-read-stdin/blob/esm/README.md
[branches-url]: https://github.com/stdlib-js/process-read-stdin/blob/main/branches.md

[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/process-read-stdin/main/LICENSE

[buffer]: https://nodejs.org/api/buffer.html

[tty]: https://nodejs.org/api/tty.html#tty_tty

[@stdlib/streams/node/stdin]: https://www.npmjs.com/package/@stdlib/streams-node-stdin

</section>

<!-- /.links -->