hardSystem Design

When would you use `child_process` module in Node.js?

Q: When would you use `child_process` module in Node.js?

**TL;DR.** Use child_process to **run external programs or separate processes** from Node — shelling out to CLI tools (git, ffmpeg, imagemagick), parallelizing CPU-heavy work across processes, or isolating untrusted/crash-prone code. Each child has its **own memory and event loop**, so a crash or heavy CPU there won't freeze the parent. Node parent ffmpeg

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This question delves into understanding how Node.js can interact with the operating system and execute external programs.

child_processsystem callsconcurrencyperformance

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Shell out to ffmpeg safely (no shell)

import { execFile } from 'node:child_process';

// execFile avoids a shell → no injection from the filename arg
execFile('ffmpeg', ['-i', input, '-vf', 'scale=640:-1', output],
  (err, stdout, stderr) => {
    if (err) return console.error('transcode failed', stderr);
    console.log('done');
  });

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