npm package: @stdlib/string-substring-before-cli
Description: Return the part of a string before a specified substring.
Author: The Stdlib Authors
Latest version: 0.2.3

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    About stdlib...
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# substringBefore

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

> Return the part of a string before a specified substring.

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<section class="intro">

</section>

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<section class="cli">



<section class="installation">

## Installation

To use as a general utility, install the CLI package globally

```bash
npm install -g @stdlib/string-substring-before-cli
```

</section>
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<section class="usage">

## Usage

```text
Usage: substring-before [options] --search=<string> [<string>]

Options:

  -h,    --help                Print this message.
  -V,    --version             Print the package version.
         --search string       Search string.
         --split sep           Delimiter for stdin data. Default: '/\\r?\\n/'.
```

</section>

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<section class="notes">

## Notes

-   If the split separator is a [regular expression][mdn-regexp], ensure that the `split` option is either properly escaped or enclosed in quotes.

    ```bash
    # Not escaped...
    $ echo -n $'foo\nbar\nbaz' | substring-before --search a --split /\r?\n/

    # Escaped...
    $ echo -n $'foo\nbar\nbaz' | substring-before --search a --split /\\r?\\n/
    ```

-   The implementation ignores trailing delimiters.

</section>

<!-- /.notes -->

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<section class="examples">

## Examples

```bash
$ substring-before abcdefg --search d
abc
```

To use as a [standard stream][standard-streams],

```bash
$ echo -n $'beep\nboop' | substring-before --search p
bee
boo
```

By default, when used as a [standard stream][standard-streams], the implementation assumes newline-delimited data. To specify an alternative delimiter, set the `split` option.

```bash
$ echo -n 'beep\tboop' | substring-before --search p --split '\t'
bee
boo
```

</section>

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</section>

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<section class="references">

</section>

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<section class="related">

## See Also

-   <span class="package-name">[`@stdlib/string-substring-before`][@stdlib/string-substring-before]</span><span class="delimiter">: </span><span class="description">return the part of a string before a specified substring.</span>
-   <span class="package-name">[`@stdlib/string-substring-before-cli-last`][@stdlib/string/substring-before-last]</span><span class="delimiter">: </span><span class="description">return the part of a string before the last occurrence of a specified substring.</span>
-   <span class="package-name">[`@stdlib/string-substring-after`][@stdlib/string/substring-after]</span><span class="delimiter">: </span><span class="description">return the part of a string after a specified substring.</span>
-   <span class="package-name">[`@stdlib/string-substring-after-last`][@stdlib/string/substring-after-last]</span><span class="delimiter">: </span><span class="description">return the part of a string after the last occurrence of a specified substring.</span>

</section>

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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>

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[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/string-substring-before/tree/deno
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[umd-url]: https://github.com/stdlib-js/string-substring-before/tree/umd
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[esm-url]: https://github.com/stdlib-js/string-substring-before/tree/esm
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[branches-url]: https://github.com/stdlib-js/string-substring-before/blob/main/branches.md

[stdlib-license]: https://raw.githubusercontent.com/stdlib-js/string-substring-before/main/LICENSE

[standard-streams]: https://en.wikipedia.org/wiki/Standard_streams

[mdn-regexp]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions

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[@stdlib/string/substring-before-last]: https://www.npmjs.com/package/@stdlib/string-substring-before-last

[@stdlib/string/substring-after]: https://www.npmjs.com/package/@stdlib/string-substring-after

[@stdlib/string/substring-after-last]: https://www.npmjs.com/package/@stdlib/string-substring-after-last

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