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The Node os module

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The os module of Node.js provides useful functions to interact with underlying system

This module provides many functions that you can use to retrieve information from the underlying operating system and the computer the program runs on, and interact with it.

const os = require('os')

There are a few useful properties that tell us some key things related to handling files:

os.EOL gives the line delimiter sequence. It’s \n on Linux and macOS, and \r\n on Windows.

When I say Linux and macOS I mean POSIX platforms. For simplicity I exclude other less popular operating systems Node can run on.

os.constants.signals tells us all the constants related to handling process signals, like SIGHUP, SIGKILL and so on.

os.constants.errno sets the constants for error reporting, like EADDRINUSE, EOVERFLOW and more.

You can read them all on https://nodejs.org/api/os.html#os_signal_constants.

Let’s now see the main methods that os provides:

os.arch()

Return the string that identifies the underlying architecture, like arm, x64, arm64.

os.cpus()

Return information on the CPUs available on your system.

Example:

[ { model: 'Intel(R) Core(TM)2 Duo CPU     P8600  @ 2.40GHz',
    speed: 2400,
    times:
     { user: 281685380,
       nice: 0,
       sys: 187986530,
       idle: 685833750,
       irq: 0 } },
  { model: 'Intel(R) Core(TM)2 Duo CPU     P8600  @ 2.40GHz',
    speed: 2400,
    times:
     { user: 282348700,
       nice: 0,
       sys: 161800480,
       idle: 703509470,
       irq: 0 } } ]

os.endianness()

Return BE or LE depending if Node was compiled with Big Endian or Little Endian.

os.freemem()

Return the number of bytes that represent the free memory in the system.

os.homedir()

Return the path to the home directory of the current user.

Example:

'/Users/flavio'

os.hostname()

Return the hostname.

os.loadavg()

Return the calculation made by the operating system on the load average.

It only returns a meaningful value on Linux and macOS.

Example:

[ 3.68798828125, 4.00244140625, 11.1181640625 ]

os.networkInterfaces()

Returns the details of the network interfaces available on your system.

Example:

{ lo0:
   [ { address: '127.0.0.1',
       netmask: '255.0.0.0',
       family: 'IPv4',
       mac: 'fe:82:00:00:00:00',
       internal: true },
     { address: '::1',
       netmask: 'ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff',
       family: 'IPv6',
       mac: 'fe:82:00:00:00:00',
       scopeid: 0,
       internal: true },
     { address: 'fe80::1',
       netmask: 'ffff:ffff:ffff:ffff::',
       family: 'IPv6',
       mac: 'fe:82:00:00:00:00',
       scopeid: 1,
       internal: true } ],
  en1:
   [ { address: 'fe82::9b:8282:d7e6:496e',
       netmask: 'ffff:ffff:ffff:ffff::',
       family: 'IPv6',
       mac: '06:00:00:02:0e:00',
       scopeid: 5,
       internal: false },
     { address: '192.168.1.38',
       netmask: '255.255.255.0',
       family: 'IPv4',
       mac: '06:00:00:02:0e:00',
       internal: false } ],
  utun0:
   [ { address: 'fe80::2513:72bc:f405:61d0',
       netmask: 'ffff:ffff:ffff:ffff::',
       family: 'IPv6',
       mac: 'fe:80:00:20:00:00',
       scopeid: 8,
       internal: false } ] }

os.platform()

Return the platform that Node was compiled for:

os.release()

Returns a string that identifies the operating system release number

os.tmpdir()

Returns the path to the assigned temp folder.

os.totalmem()

Returns the number of bytes that represent the total memory available in the system.

os.type()

Identifies the operating system:

os.uptime()

Returns the number of seconds the computer has been running since it was last rebooted.

os.userInfo()

Returns information about the current user

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