spawn for streaming processes in Node.js - Mini Project: Build & Apply

Using spawn for Streaming Processes in Node.js

📖 Scenario: You want to run a system command from your Node.js program and handle its output as it happens, like watching a live feed.

🎯 Goal: Build a Node.js script that uses spawn from the child_process module to run the ping command and stream its output live to the console.

📋 What You'll Learn

Import the spawn function from the child_process module

Create a child process that runs the ping command with -c 4 to send 4 pings

Listen to the child process's stdout stream and print each chunk of data as it arrives

Listen to the child process's stderr stream and print errors if any

Listen for the child process to exit and print the exit code

💡 Why This Matters

🌍 Real World

Running system commands from Node.js is common for automation, monitoring, or integrating other tools. Streaming output lets you handle data as it arrives, useful for live logs or progress.

💼 Career

Understanding how to spawn child processes and stream their output is important for backend developers, DevOps engineers, and anyone working with Node.js automation or system integration.

1

Import spawn from child_process

Write a line to import spawn from the child_process module using destructuring assignment.

Node.js

# Import spawn from child_process
# Your code here

Need a hint?

Use const { spawn } = require('child_process'); to import spawn.

2

Create a child process to run ping

Create a constant called pingProcess that runs the ping command with arguments -c and 4 using spawn.

Node.js

const { spawn } = require('child_process');

# Create pingProcess to run 'ping -c 4'
# Your code here

Need a hint?

Use spawn('ping', ['-c', '4']) to run ping 4 times.

3

Stream stdout and stderr data

Add event listeners to pingProcess.stdout and pingProcess.stderr to listen for data events. For each event, print the chunk as a string to the console using console.log.

Node.js

const { spawn } = require('child_process');

const pingProcess = spawn('ping', ['-c', '4']);

# Listen to stdout and stderr data events
# Your code here

Need a hint?

Use pingProcess.stdout.on('data', (data) => { console.log(`stdout: ${data}`); }) and similarly for stderr.

4

Handle process exit event

Add an event listener to pingProcess for the close event. When the process closes, print Process exited with code: followed by the exit code.

Node.js

const { spawn } = require('child_process');

const pingProcess = spawn('ping', ['-c', '4']);

pingProcess.stdout.on('data', (data) => {
  console.log(`stdout: ${data}`);
});

pingProcess.stderr.on('data', (data) => {
  console.log(`stderr: ${data}`);
});

# Listen for the close event and print exit code
# Your code here

Need a hint?

Use pingProcess.on('close', (code) => { console.log(`Process exited with code: ${code}`); }).