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1# cross-spawn
2
3[![NPM version][npm-image]][npm-url] [![Downloads][downloads-image]][npm-url] [![Build Status][travis-image]][travis-url] [![Build status][appveyor-image]][appveyor-url] [![Coverage Status][codecov-image]][codecov-url] [![Dependency status][david-dm-image]][david-dm-url] [![Dev Dependency status][david-dm-dev-image]][david-dm-dev-url]
4
5[npm-url]:https://npmjs.org/package/cross-spawn
6[downloads-image]:https://img.shields.io/npm/dm/cross-spawn.svg
7[npm-image]:https://img.shields.io/npm/v/cross-spawn.svg
8[travis-url]:https://travis-ci.org/moxystudio/node-cross-spawn
9[travis-image]:https://img.shields.io/travis/moxystudio/node-cross-spawn/master.svg
10[appveyor-url]:https://ci.appveyor.com/project/satazor/node-cross-spawn
11[appveyor-image]:https://img.shields.io/appveyor/ci/satazor/node-cross-spawn/master.svg
12[codecov-url]:https://codecov.io/gh/moxystudio/node-cross-spawn
13[codecov-image]:https://img.shields.io/codecov/c/github/moxystudio/node-cross-spawn/master.svg
14[david-dm-url]:https://david-dm.org/moxystudio/node-cross-spawn
15[david-dm-image]:https://img.shields.io/david/moxystudio/node-cross-spawn.svg
16[david-dm-dev-url]:https://david-dm.org/moxystudio/node-cross-spawn?type=dev
17[david-dm-dev-image]:https://img.shields.io/david/dev/moxystudio/node-cross-spawn.svg
18
19A cross platform solution to node's spawn and spawnSync.
20
21
22## Installation
23
24Node.js version 8 and up:
25`$ npm install cross-spawn`
26
27Node.js version 7 and under:
28`$ npm install cross-spawn@6`
29
30## Why
31
32Node has issues when using spawn on Windows:
33
34- It ignores [PATHEXT](https://github.com/joyent/node/issues/2318)
35- It does not support [shebangs](https://en.wikipedia.org/wiki/Shebang_(Unix))
36- Has problems running commands with [spaces](https://github.com/nodejs/node/issues/7367)
37- Has problems running commands with posix relative paths (e.g.: `./my-folder/my-executable`)
38- Has an [issue](https://github.com/moxystudio/node-cross-spawn/issues/82) with command shims (files in `node_modules/.bin/`), where arguments with quotes and parenthesis would result in [invalid syntax error](https://github.com/moxystudio/node-cross-spawn/blob/e77b8f22a416db46b6196767bcd35601d7e11d54/test/index.test.js#L149)
39- No `options.shell` support on node `<v4.8`
40
41All these issues are handled correctly by `cross-spawn`.
42There are some known modules, such as [win-spawn](https://github.com/ForbesLindesay/win-spawn), that try to solve this but they are either broken or provide faulty escaping of shell arguments.
43
44
45## Usage
46
47Exactly the same way as node's [`spawn`](https://nodejs.org/api/child_process.html#child_process_child_process_spawn_command_args_options) or [`spawnSync`](https://nodejs.org/api/child_process.html#child_process_child_process_spawnsync_command_args_options), so it's a drop in replacement.
48
49
50```js
51const spawn = require('cross-spawn');
52
53// Spawn NPM asynchronously
54const child = spawn('npm', ['list', '-g', '-depth', '0'], { stdio: 'inherit' });
55
56// Spawn NPM synchronously
57const result = spawn.sync('npm', ['list', '-g', '-depth', '0'], { stdio: 'inherit' });
58```
59
60
61## Caveats
62
63### Using `options.shell` as an alternative to `cross-spawn`
64
65Starting from node `v4.8`, `spawn` has a `shell` option that allows you run commands from within a shell. This new option solves
66the [PATHEXT](https://github.com/joyent/node/issues/2318) issue but:
67
68- It's not supported in node `<v4.8`
69- You must manually escape the command and arguments which is very error prone, specially when passing user input
70- There are a lot of other unresolved issues from the [Why](#why) section that you must take into account
71
72If you are using the `shell` option to spawn a command in a cross platform way, consider using `cross-spawn` instead. You have been warned.
73
74### `options.shell` support
75
76While `cross-spawn` adds support for `options.shell` in node `<v4.8`, all of its enhancements are disabled.
77
78This mimics the Node.js behavior. More specifically, the command and its arguments will not be automatically escaped nor shebang support will be offered. This is by design because if you are using `options.shell` you are probably targeting a specific platform anyway and you don't want things to get into your way.
79
80### Shebangs support
81
82While `cross-spawn` handles shebangs on Windows, its support is limited. More specifically, it just supports `#!/usr/bin/env <program>` where `<program>` must not contain any arguments.
83If you would like to have the shebang support improved, feel free to contribute via a pull-request.
84
85Remember to always test your code on Windows!
86
87
88## Tests
89
90`$ npm test`
91`$ npm test -- --watch` during development
92
93
94## License
95
96Released under the [MIT License](https://www.opensource.org/licenses/mit-license.php).