Node.js os Module

Java FileNode.js built-in modules

Node.js'sosos module is a built-in core module that provides practical methods and properties related to the operating system. Through this module, we can obtain various information about the operating system on which Node.js is currently running, such as CPU architecture, memory usage, network interfaces, etc.

Why do we need the os module?

When developing applications, sometimes we need to perform different operations based on different operating system environments, or we need to monitor the system's resource usage.osThe os module provides us with this capability, allowing us to easily obtain this system information.

How to use the os module

To useosthe module, we first need to import it:

const os = require('os');

Introduction to common methods

1. Get operating system information

Example

console.log(os.platform());  // Returns the operating system platform, e.g., 'darwin', 'win32', 'linux'
console.log(os.type());      // Returns the operating system name, e.g., 'Linux', 'Darwin', 'Windows_NT'
console.log(os.arch());      // Returns the CPU architecture, e.g., 'x64', 'arm'
console.log(os.release());   // Returns the operating system version

2. Get memory information

Example

console.log(os.totalmem());  // Returns the total system memory (bytes)
console.log(os.freemem());   // Returns the available system memory (bytes)

// Convert to MB for display
console.log(`Total memory: ${os.totalmem() / 1024 / 1024} MB`);
console.log(`Available memory: ${os.freemem() / 1024 / 1024} MB`);

3. Get CPU information

Example

console.log(os.cpus());      // Returns an array of objects containing information about each CPU/core
console.log(os.loadavg());   // Returns the average load for 1, 5, and 15 minutes (Linux/Unix only)

// Get the number of CPU cores
console.log(`Number of CPU cores: ${os.cpus().length}`);

4. Get network interface information

Example

console.log(os.networkInterfaces());  // Returns network interface information

5. Get user-related information

Example

console.log(os.homedir());   // Returns the home directory of the current user
console.log(os.userInfo());  // Returns information about the current user
console.log(os.hostname());  // Returns the hostname of the operating system

Practical application examples

Example 1: System monitoring tool

Example

const os = require('os');

function systemMonitor() {
  console.log('=== System monitoring ===');
  console.log(`Operating system: ${os.type()} ${os.release()}`);
  console.log(`CPU architecture: ${os.arch()}`);
  console.log(`Number of CPU cores: ${os.cpus().length}`);
  console.log(`Total memory: ${(os.totalmem() / 1024 / 1024).toFixed(2)} MB`);
  console.log(`Available memory: ${(os.freemem() / 1024 / 1024).toFixed(2)} MB`);
  console.log(`System uptime: ${(os.uptime() / 60 / 60).toFixed(2)}hours`);
}

systemMonitor();

Example 2: Get network IP address

Example

const os = require('os');

function getLocalIP() {
  const interfaces = os.networkInterfaces();
  for (const interfaceName in interfaces) {
    for (const iface of interfaces[interfaceName]) {
      if (iface.family === 'IPv4' && !iface.internal) {
        return iface.address;
      }
    }
  }
  return '127.0.0.1';
}

console.log(`Local IP address: ${getLocalIP()}`);

Notes

  1. osThe information provided by the os module is read-only and cannot be used to modify system configuration.
  2. The information returned by different operating systems may vary, especially between Windows and Unix-like systems.
  3. Some methods (such asloadavg()) may not be available on Windows or may return different values.
  4. Memory information is returned in bytes and usually needs to be converted to more readable units (such as MB or GB).

Methods

The common methods and properties of os are as follows:

MethodDescriptionExample
os.arch()Returns the CPU architecture of the operating system.console.log(os.arch()); // 输出：'x64'
os.constantsReturns an object containing operating system-specific constants (such as error codes, signals, etc.).console.log(os.constants.signals);
os.cpus()Returns an array of objects, each containing information about a CPU core, such as model, speed, usage, etc.console.log(os.cpus());
os.endianness()Returns the CPU byte order (BEmeans big-endian byte order,LEmeans little-endian byte order).console.log(os.endianness()); // 输出：'LE'
os.freemem()Returns the amount of free memory of the system (in bytes), which can be used to monitor system resources.console.log(os.freemem());
os.homedir()Returns the home directory path of the current user.console.log(os.homedir());
os.hostname()Returns the hostname.console.log(os.hostname());
os.loadavg()Returns an array containing the average load for 1, 5, and 15 minutes, only valid on Unix systems.console.log(os.loadavg());
os.networkInterfaces()Returns an object containing address information for each network interface, such asIP 地址、MAC 地址。console.log(os.networkInterfaces());
os.platform()Returns the operating system platform, such as'darwin'、'win32'、'linux'etc.console.log(os.platform());
os.release()Returns the distribution version of the operating system.console.log(os.release());
os.tmpdir()Returns the default temporary file directory path of the operating system.console.log(os.tmpdir());
os.totalmem()Returns the total system memory (in bytes).console.log(os.totalmem());
os.type()Returns the name of the operating system, such as'Linux'、'Darwin'（macOS）、'Windows_NT'etc.console.log(os.type());
os.uptime()Returns the operating system uptime, in seconds.console.log(os.uptime());
os.userInfo([options])Returns detailed information about the current user, such as username, home directory, UID, GID, etc. Supports configuring an options object to set the character encoding (default is'utf8'）。console.log(os.userInfo());

Properties

PropertyDescriptionExample
os.EOLReturns the end-of-line marker for the current operating system (\nor\r\n), convenient for handling cross-platform file reading and writing.console.log(os.EOL); // Windows 输出：'\r\n'，Linux 输出：'\n'

Example

Create a main.js file with the following code:

Example

const os = require('os');

// Get system architecture
console.log('System architecture:', os.arch());

// Get CPU information
console.log('CPU information:', os.cpus());

// Get free memory
console.log('Free memory:', os.freemem());

// Get total memory
console.log('Total memory:', os.totalmem());

// Get home directory
console.log('Home directory:', os.homedir());

// Get system platform
console.log('System platform:', os.platform());

// Get system name
console.log('System name:', os.type());

// Get average load (only applies to Unix systems)
console.log('Average load:', os.loadavg());

// Get network interface information
console.log('Network interface information:', os.networkInterfaces());

The code execution result is similar to the following:

系统架构: arm64
CPU 信息: [
  {
    model: 'Apple M1',
    speed: 24,
    times: { user: 18515240, nice: 0, sys: 9460280, idle: 38401220, irq: 0 }
  }
...
]
空闲内存: 167411712
总内存: 8589934592
主目录: /Users/EXAMPLE
系统平台: darwin
系统名称: Darwin
平均负载: [ 11.4658203125, 4.49560546875, 3.35791015625 ]
网络接口信息: {
...

Node.js 工具模块Node.js utility modules

Java FileNode.js built-in modules

Other extensions