https://github.com/thlorenz/ispawn

Spawn a process to inspect it.
https://github.com/thlorenz/ispawn

Last synced: 2 months ago
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Spawn a process to inspect it.

• Host: GitHub
• URL: https://github.com/thlorenz/ispawn
• Owner: thlorenz
• License: mit
• Created: 2018-07-31T17:32:52.000Z (over 6 years ago)
• Default Branch: master
• Last Pushed: 2018-08-03T17:26:52.000Z (over 6 years ago)
• Last Synced: 2024-10-18T00:31:35.599Z (3 months ago)
• Language: JavaScript
• Homepage: https://thlorenz.github.io/ispawn
• Size: 1.14 MB
• Stars: 5
• Watchers: 2
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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# ispawn [![build status](https://secure.travis-ci.org/thlorenz/ispawn.svg?branch=master)](http://travis-ci.org/thlorenz/ispawn)



Spawn a process to inspect it.

## Installation

    npm install ispawn

## [API](https://thlorenz.github.io/ispawn)

### createSpawn

Configures a process to be spawned but doesn't spawn it yet

**Parameters**

-   `$0` **Objects** options (same as @see `spawn`)

Returns **Spawner** that will spawn the configured process via `spawner.spawn`

### spawn

Spawns a process with the given options allowing to intercept `stdout`

and `stderr` output of the application itself or the underlying process,

i.e. V8 and Node.js messages.

#### onStdout and onStderr interceptors

The functions, `onStdout`, `onStderr` called with each line written to the

respective file descriptor have the following signature:

`onStdout(line:String, fromApp:Boolean)` where `fromApp` is `true` when the

line came from the app itself and `false` when it came from the underlying

runtime, i.e. Node.js or V8 when flags triggered diagnostics output.

To mark a line as _handled_ return `true` from the function and it will not

be printed to the console.

#### Example

```js

 function onStdout(line, fromApp) {

   // Don't intercept app output, just have it printed as usual

   if (fromApp) return false

   // Do something with diagnositics messages here ...

   return true

 }

 const { termination } = spawn({

     execArgv: [ '--trace-turbo-inlining' ]

   , argv: [ require.resolve('./bind.js') ]

   , onStdout

 })

 try {

   const code = await termination

   console.log('The app returned with code', code)

 } catch (err) {

   console.error(err)

 }

```

[full example](https://github.com/thlorenz/ispawn/blob/master/example/map-inlines)

**Parameters**

-   `$0` **[Object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)** options

    -   `$0.execArgv` **[Array](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array)<[String](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String)>?** arguments passed to Node.js/V8 directly (not to your app) (optional, default `[]`)

    -   `$0.argv` **[Array](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array)<[String](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String)>** file to run followed by flags to pass to your app

    -   `$0.node` **[String](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String)?** path to Node.js executable (optional, default `process.execPath`)

    -   `$0.spawnOpts` **[Object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)?** options passed to `child_process.spawn` (optional, default `{}`)

    -   `$0.onStdout` **[Function](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/function)?** function to call with each line written to stdout (optional, default `null`)

    -   `$0.onStderr` **[Function](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Statements/function)?** function to call with each line written to stderr (optional, default `null`)

Returns **[Object](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object)** with the following properties-   termination: {Promise} that resolves when process exits

-   proc: the spawned process

## Kudos

Lots of the ideas and code were extracted from the [0x

tool](https://github.com/davidmarkclements/0x).

## License

MIT