How to spawn child processes in Node.js

Short answer

Use child_process.spawn() for long-running processes with streaming output, and child_process.exec() for short commands that return small output buffers.

Steps

1. Import the module: const { spawn, exec } = require('child_process');.
2. Spawn a process: const ls = spawn('ls', ['-la']);.
3. Listen to stdout: ls.stdout.on('data', data => console.log(data.toString()));.
4. Use exec for simple commands: exec('node -v', (err, stdout) => { ... });.
5. Always handle the error and close events.

Tips

• spawn is more efficient for large outputs because it streams data. exec buffers the entire output and has a default max buffer limit.
• Use execFile when you do not need a shell and want slightly better performance.

Common issues

• Command injection is possible if you pass unsanitized user input to exec or spawn with shell: true.
• The working directory of the child process defaults to the parent process; set cwd explicitly if needed.