How to use child processes in Node.js
Łukasz Holeczek
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Child processes enable Node.js applications to execute external commands, scripts, and programs in separate processes with proper resource isolation. As the creator of CoreUI, a widely used open-source UI library, I’ve implemented child process management in Node.js applications throughout my 11 years of backend development. The most versatile approach is using the child_process module’s spawn method for streaming output and flexible command execution. This method provides real-time output handling and better memory management for long-running processes.
Use the spawn method from child_process to execute commands with streaming output.
const { spawn } = require('child_process')
const runCommand = (command, args) => {
const child = spawn(command, args)
child.stdout.on('data', (data) => {
console.log(`Output: ${data}`)
})
child.stderr.on('data', (data) => {
console.error(`Error: ${data}`)
})
child.on('close', (code) => {
console.log(`Process exited with code ${code}`)
})
return child
}
runCommand('ls', ['-la'])
Here the spawn method creates a child process executing the specified command with arguments. Output streams (stdout and stderr) are accessible as the process runs, enabling real-time logging. The close event fires when the process exits, providing the exit code. This approach handles large outputs efficiently without buffering everything in memory.
Best Practice Note:
This is the approach we use in CoreUI build automation and deployment scripts for executing external tools. Use spawn for long-running processes with streaming output, exec for simple commands needing buffered output, and always handle stderr and error events to prevent unhandled errors from crashing your application.
