child-process-promise

What is child-process-promise?

The 'child-process-promise' npm package is a utility that provides a promise-based interface for Node.js's child_process module. It allows you to execute shell commands and spawn new processes with the added benefit of using promises for better asynchronous control.

What are child-process-promise's main functionalities?

exec

The 'exec' function allows you to run a shell command and returns a promise that resolves with the command's output. This is useful for running simple shell commands and capturing their output.

const { exec } = require('child-process-promise');

exec('ls -la')
  .then(result => {
    console.log('stdout:', result.stdout);
    console.log('stderr:', result.stderr);
  })
  .catch(err => {
    console.error('ERROR:', err);
  });

spawn

The 'spawn' function allows you to start a new process using a given command and arguments. It returns a promise that resolves when the process completes. This is useful for more complex scenarios where you need to interact with the process's input/output streams.

const { spawn } = require('child-process-promise');

const child = spawn('ls', ['-la']);

child.childProcess.stdout.on('data', data => {
  console.log('stdout:', data.toString());
});

child.childProcess.stderr.on('data', data => {
  console.error('stderr:', data.toString());
});

child.then(() => {
  console.log('Process completed');
}).catch(err => {
  console.error('ERROR:', err);
});

Other packages similar to child-process-promise

execa

Execa is a modern alternative to child_process that provides a promise-based interface for executing shell commands. It offers more features and better defaults compared to child-process-promise, such as improved error handling and support for streaming output.

promisify-child-process

Promisify-child-process is another package that wraps Node.js's child_process module with promises. It provides a similar interface to child-process-promise but focuses on being a lightweight and minimalistic solution.

node-cmd

Node-cmd is a simple package for executing shell commands in Node.js. It provides a callback-based interface but can be easily used with promises using utilities like util.promisify. It is less feature-rich compared to child-process-promise but can be a good choice for simpler use cases.

README

child-process-promise

Simple wrapper around the child_process module that makes use of promises

Installation

npm install child-process-promise --save

Usage

exec

var exec = require('child-process-promise').exec;

exec('echo hello')
    .then(function (result) {
        var stdout = result.stdout;
        var stderr = result.stderr;
        console.log('stdout: ', stdout);
        console.log('stderr: ', stderr);
    })
    .fail(function (err) {
        console.error('ERROR: ', err);
    })
    .progress(function (childProcess) {
        console.log('childProcess.pid: ', childProcess.pid);
    });

spawn

var spawn = require('child-process-promise').spawn;

spawn('echo', ['hello'])
    .progress(function (childProcess) {
        console.log('[spawn] childProcess.pid: ', childProcess.pid);
        childProcess.stdout.on('data', function (data) {
            console.log('[spawn] stdout: ', data.toString());
        });
        childProcess.stderr.on('data', function (data) {
            console.log('[spawn] stderr: ', data.toString());
        });
    })
    .then(function () {
        console.log('[spawn] done!');
    })
    .fail(function (err) {
        console.error('[spawn] ERROR: ', err);
    });

Options

capture

Type: Array
Default: []

Pass an additional capture option to buffer the result of stdout and/or stderr

var spawn = require('child-process-promise').spawn;

spawn('echo', ['hello'], { capture: [ 'stdout', 'stderr' ]})
    .then(function (result) {
        console.log('[spawn] stdout: ', result.stdout.toString());
    })
    .fail(function (err) {
        console.error('[spawn] stderr: ', err.stderr);
    });