cross-spawn vs execa vs spawn-sync
Process Management in Node.js Comparison
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What's Process Management in Node.js?

Process management libraries in Node.js provide tools for spawning and managing child processes from within a Node.js application. These libraries allow developers to execute external commands, scripts, or binaries, handle their input/output streams, and manage their execution in a non-blocking or synchronous manner. This is particularly useful for tasks like running shell commands, automating scripts, or integrating with other system-level processes. Each library offers different features and APIs to cater to various use cases, such as handling complex command execution, managing process lifecycles, and providing better error handling and performance.

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cross-spawn97,455,7021,14416.1 kB266 months agoMIT
execa93,277,4537,149324 kB143 days agoMIT
spawn-sync1,076,42236-07 years agoMIT
Feature Comparison: cross-spawn vs execa vs spawn-sync

Cross-Platform Compatibility

  • cross-spawn:

    cross-spawn is designed to handle cross-platform compatibility issues when spawning child processes. It correctly handles the execution of commands on Windows, macOS, and Linux, ensuring that arguments are passed correctly regardless of the operating system.

  • execa:

    execa also provides good cross-platform compatibility, but it is built on top of the native child_process module, which means it inherits some of its quirks. However, execa offers a more modern API and better handles edge cases, making it a reliable choice for cross-platform applications.

  • spawn-sync:

    spawn-sync is a synchronous wrapper around the native child_process module. While it is cross-platform in nature, it does not provide any additional features or handling for cross-platform issues. It is best used in scenarios where platform-specific behavior is not a concern.

API Design

  • cross-spawn:

    cross-spawn provides a simple and straightforward API for spawning child processes. It focuses on simplicity and ease of use, making it easy to integrate into existing projects without a steep learning curve.

  • execa:

    execa offers a more modern and feature-rich API compared to the built-in child_process module. It supports promises and async/await, making it more suitable for modern JavaScript applications. The API is designed to be intuitive and easy to use, with additional features like execa.sync for synchronous execution.

  • spawn-sync:

    spawn-sync provides a minimalistic API for synchronously spawning child processes. It is straightforward and easy to use, but it lacks the advanced features and flexibility offered by the other libraries.

Error Handling

  • cross-spawn:

    cross-spawn provides basic error handling for child processes. It emits errors when the process fails to spawn or exits with a non-zero status code. However, it does not provide detailed error information or support for promise-based error handling.

  • execa:

    execa offers much better error handling compared to the other libraries. It throws an ExecaError for failed processes, which includes detailed information about the error, such as the exit code, stdout, and stderr. This makes it easier to handle errors and debug issues when working with child processes.

  • spawn-sync:

    spawn-sync provides basic error handling for synchronous process spawning. It throws an error if the process fails to spawn or exits with a non-zero status code, but it does not provide any additional error information or context.

Synchronous vs Asynchronous Execution

  • cross-spawn:

    cross-spawn is primarily designed for asynchronous process spawning. It uses callbacks to handle process output and errors, allowing the main thread to continue executing while the child process runs in the background.

  • execa:

    execa supports both asynchronous and synchronous execution of child processes. It provides a promise-based API for async execution and also offers a synchronous method (execa.sync) for cases where blocking the main thread is acceptable.

  • spawn-sync:

    spawn-sync is focused solely on synchronous execution. It blocks the main thread until the child process completes, making it suitable for scripts or applications where synchronous behavior is required.

Ease of Use: Code Examples

  • cross-spawn:

    Simple cross-platform process spawning with cross-spawn

    const spawn = require('cross-spawn');
    const child = spawn('echo', ['Hello, World!']);
    
    child.stdout.on('data', (data) => {
      console.log(`Output: ${data}`);
    });
    
    child.stderr.on('data', (data) => {
      console.error(`Error: ${data}`);
    });
    
    child.on('close', (code) => {
      console.log(`Child process exited with code ${code}`);
    });
    
  • execa:

    Asynchronous process execution with execa

    const { execa } = require('execa');
    
    (async () => {
      try {
        const { stdout } = await execa('echo', ['Hello from Execa!']);
        console.log(stdout);
      } catch (error) {
        console.error(`Error: ${error.message}`);
      }
    })();
    
  • spawn-sync:

    Synchronous process execution with spawn-sync

    const spawnSync = require('spawn-sync');
    const result = spawnSync('echo', ['Hello from Spawn-Sync!']);
    
    console.log(result.stdout.toString());
    if (result.error) {
      console.error(`Error: ${result.error.message}`);
    }
    
How to Choose: cross-spawn vs execa vs spawn-sync
  • cross-spawn:

    Choose cross-spawn if you need a simple and reliable way to spawn child processes across different platforms, especially when dealing with cross-platform compatibility issues. It handles arguments and environment variables correctly, making it a good choice for most use cases.

  • execa:

    Choose execa if you need a feature-rich and modern alternative to the built-in child_process module. It offers a promise-based API, better error handling, and additional features like streaming, timeout support, and improved handling of subprocesses, making it ideal for more complex scenarios.

  • spawn-sync:

    Choose spawn-sync if you require a synchronous method for spawning child processes. This is useful for scripts or applications where blocking the main thread is acceptable, and you need to ensure that the child process completes before continuing execution.

README for cross-spawn

cross-spawn

NPM version Downloads Build Status Build status

A cross platform solution to node's spawn and spawnSync.

Installation

Node.js version 8 and up: $ npm install cross-spawn

Node.js version 7 and under: $ npm install cross-spawn@6

Why

Node has issues when using spawn on Windows:

  • It ignores PATHEXT
  • It does not support shebangs
  • Has problems running commands with spaces
  • Has problems running commands with posix relative paths (e.g.: ./my-folder/my-executable)
  • Has an issue with command shims (files in node_modules/.bin/), where arguments with quotes and parenthesis would result in invalid syntax error
  • No options.shell support on node <v4.8

All these issues are handled correctly by cross-spawn. There are some known modules, such as win-spawn, that try to solve this but they are either broken or provide faulty escaping of shell arguments.

Usage

Exactly the same way as node's spawn or spawnSync, so it's a drop in replacement.

const spawn = require('cross-spawn');

// Spawn NPM asynchronously
const child = spawn('npm', ['list', '-g', '-depth', '0'], { stdio: 'inherit' });

// Spawn NPM synchronously
const result = spawn.sync('npm', ['list', '-g', '-depth', '0'], { stdio: 'inherit' });

Caveats

Using options.shell as an alternative to cross-spawn

Starting from node v4.8, spawn has a shell option that allows you run commands from within a shell. This new option solves the PATHEXT issue but:

  • It's not supported in node <v4.8
  • You must manually escape the command and arguments which is very error prone, specially when passing user input
  • There are a lot of other unresolved issues from the Why section that you must take into account

If you are using the shell option to spawn a command in a cross platform way, consider using cross-spawn instead. You have been warned.

options.shell support

While cross-spawn adds support for options.shell in node <v4.8, all of its enhancements are disabled.

This 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.

Shebangs support

While 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.
If you would like to have the shebang support improved, feel free to contribute via a pull-request.

Remember to always test your code on Windows!

Tests

$ npm test
$ npm test -- --watch during development

License

Released under the MIT License.