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<!DOCTYPE html> <html lang="en"> <head> <meta charset="utf-8"> <meta name="viewport" content="width=device-width"> <meta name="nodejs.org:node-version" content="v22.22.0"> <title>OS | Node.js v22.22.0 Documentation</title> <link rel="stylesheet" href="https://fonts.googleapis.com/css?family=Lato:400,700,400italic&display=fallback"> <link rel="stylesheet" href="assets/style.css"> <link rel="stylesheet" href="assets/hljs.css"> <link rel="canonical" href="https://nodejs.org/api/os.html"> <script async defer src="assets/api.js" type="text/javascript"></script> <script> const storedTheme = localStorage.getItem('theme'); // Follow operating system theme preference if (storedTheme === null && window.matchMedia) { const mq = window.matchMedia('(prefers-color-scheme: dark)'); if (mq.matches) { document.documentElement.classList.add('dark-mode'); } } else if (storedTheme === 'dark') { document.documentElement.classList.add('dark-mode'); } </script> 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href="#oscpus"><code>os.cpus()</code></a></li> <li><a href="#osdevnull"><code>os.devNull</code></a></li> <li><a href="#osendianness"><code>os.endianness()</code></a></li> <li><a href="#osfreemem"><code>os.freemem()</code></a></li> <li><a href="#osgetprioritypid"><code>os.getPriority([pid])</code></a></li> <li><a href="#oshomedir"><code>os.homedir()</code></a></li> <li><a href="#oshostname"><code>os.hostname()</code></a></li> <li><a href="#osloadavg"><code>os.loadavg()</code></a></li> <li><a href="#osmachine"><code>os.machine()</code></a></li> <li><a href="#osnetworkinterfaces"><code>os.networkInterfaces()</code></a></li> <li><a href="#osplatform"><code>os.platform()</code></a></li> <li><a href="#osrelease"><code>os.release()</code></a></li> <li><a href="#ossetprioritypid-priority"><code>os.setPriority([pid, ]priority)</code></a></li> <li><a href="#ostmpdir"><code>os.tmpdir()</code></a></li> <li><a href="#ostotalmem"><code>os.totalmem()</code></a></li> <li><a href="#ostype"><code>os.type()</code></a></li> <li><a href="#osuptime"><code>os.uptime()</code></a></li> <li><a href="#osuserinfooptions"><code>os.userInfo([options])</code></a></li> <li><a href="#osversion"><code>os.version()</code></a></li> <li><a href="#os-constants">OS constants</a> <ul> <li><a href="#signal-constants">Signal constants</a></li> <li><a href="#error-constants">Error constants</a> <ul> <li><a href="#posix-error-constants">POSIX error constants</a></li> <li><a href="#windows-specific-error-constants">Windows-specific error constants</a></li> </ul> </li> <li><a href="#dlopen-constants">dlopen constants</a></li> <li><a href="#priority-constants">Priority constants</a></li> <li><a href="#libuv-constants">libuv constants</a></li> </ul> </li> </ul> </li> </ul></div></div> </li> <li class="picker-header"> <a href="#gtoc-picker" aria-controls="gtoc-picker"> <span class="picker-arrow"></span> Index </a> <div class="picker" tabindex="-1" id="gtoc-picker"><ul> <li><a href="documentation.html" class="nav-documentation">About this documentation</a></li> <li><a href="synopsis.html" class="nav-synopsis">Usage and example</a></li> <li> <a href="index.html">Index</a> </li> </ul> <hr class="line"> <ul> <li><a href="assert.html" class="nav-assert">Assertion testing</a></li> <li><a href="async_context.html" class="nav-async_context">Asynchronous context tracking</a></li> <li><a href="async_hooks.html" class="nav-async_hooks">Async hooks</a></li> <li><a href="buffer.html" class="nav-buffer">Buffer</a></li> <li><a href="addons.html" class="nav-addons">C++ addons</a></li> <li><a href="n-api.html" class="nav-n-api">C/C++ addons with Node-API</a></li> <li><a href="embedding.html" class="nav-embedding">C++ embedder API</a></li> <li><a href="child_process.html" class="nav-child_process">Child processes</a></li> <li><a href="cluster.html" class="nav-cluster">Cluster</a></li> <li><a href="cli.html" class="nav-cli">Command-line options</a></li> <li><a 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class="nav-https">HTTPS</a></li> <li><a href="inspector.html" class="nav-inspector">Inspector</a></li> <li><a href="intl.html" class="nav-intl">Internationalization</a></li> <li><a href="modules.html" class="nav-modules">Modules: CommonJS modules</a></li> <li><a href="esm.html" class="nav-esm">Modules: ECMAScript modules</a></li> <li><a href="module.html" class="nav-module">Modules: <code>node:module</code> API</a></li> <li><a href="packages.html" class="nav-packages">Modules: Packages</a></li> <li><a href="typescript.html" class="nav-typescript">Modules: TypeScript</a></li> <li><a href="net.html" class="nav-net">Net</a></li> <li><a href="os.html" class="nav-os active">OS</a></li> <li><a href="path.html" class="nav-path">Path</a></li> <li><a href="perf_hooks.html" class="nav-perf_hooks">Performance hooks</a></li> <li><a href="permissions.html" class="nav-permissions">Permissions</a></li> <li><a href="process.html" class="nav-process">Process</a></li> <li><a href="punycode.html" class="nav-punycode">Punycode</a></li> <li><a href="querystring.html" class="nav-querystring">Query strings</a></li> <li><a href="readline.html" class="nav-readline">Readline</a></li> <li><a href="repl.html" class="nav-repl">REPL</a></li> <li><a href="report.html" class="nav-report">Report</a></li> <li><a href="single-executable-applications.html" class="nav-single-executable-applications">Single executable applications</a></li> <li><a href="sqlite.html" class="nav-sqlite">SQLite</a></li> <li><a href="stream.html" class="nav-stream">Stream</a></li> <li><a href="string_decoder.html" class="nav-string_decoder">String decoder</a></li> <li><a href="test.html" class="nav-test">Test runner</a></li> <li><a href="timers.html" class="nav-timers">Timers</a></li> <li><a href="tls.html" class="nav-tls">TLS/SSL</a></li> <li><a href="tracing.html" class="nav-tracing">Trace events</a></li> <li><a href="tty.html" class="nav-tty">TTY</a></li> <li><a href="dgram.html" class="nav-dgram">UDP/datagram</a></li> <li><a href="url.html" class="nav-url">URL</a></li> <li><a href="util.html" class="nav-util">Utilities</a></li> <li><a href="v8.html" class="nav-v8">V8</a></li> <li><a href="vm.html" class="nav-vm">VM</a></li> <li><a href="wasi.html" class="nav-wasi">WASI</a></li> <li><a href="webcrypto.html" class="nav-webcrypto">Web Crypto API</a></li> <li><a href="webstreams.html" class="nav-webstreams">Web Streams API</a></li> <li><a href="worker_threads.html" class="nav-worker_threads">Worker threads</a></li> <li><a href="zlib.html" class="nav-zlib">Zlib</a></li> </ul> <hr class="line"> <ul> <li><a href="https://github.com/nodejs/node" class="nav-https-github-com-nodejs-node">Code repository and issue tracker</a></li> </ul></div> </li> <li class="picker-header"> <a href="#alt-docs" aria-controls="alt-docs"> <span class="picker-arrow"></span> Other versions </a> <div class="picker" tabindex="-1"><ol id="alt-docs"><li><a href="https://nodejs.org/docs/latest-v25.x/api/os.html">25.x</a></li> <li><a href="https://nodejs.org/docs/latest-v24.x/api/os.html">24.x <b>LTS</b></a></li> <li><a href="https://nodejs.org/docs/latest-v23.x/api/os.html">23.x</a></li> <li><a href="https://nodejs.org/docs/latest-v22.x/api/os.html">22.x <b>LTS</b></a></li> <li><a href="https://nodejs.org/docs/latest-v21.x/api/os.html">21.x</a></li> <li><a href="https://nodejs.org/docs/latest-v20.x/api/os.html">20.x <b>LTS</b></a></li> <li><a href="https://nodejs.org/docs/latest-v19.x/api/os.html">19.x</a></li> <li><a href="https://nodejs.org/docs/latest-v18.x/api/os.html">18.x</a></li> <li><a href="https://nodejs.org/docs/latest-v17.x/api/os.html">17.x</a></li> <li><a href="https://nodejs.org/docs/latest-v16.x/api/os.html">16.x</a></li> <li><a href="https://nodejs.org/docs/latest-v15.x/api/os.html">15.x</a></li> <li><a href="https://nodejs.org/docs/latest-v14.x/api/os.html">14.x</a></li> <li><a href="https://nodejs.org/docs/latest-v13.x/api/os.html">13.x</a></li> <li><a href="https://nodejs.org/docs/latest-v12.x/api/os.html">12.x</a></li> <li><a href="https://nodejs.org/docs/latest-v11.x/api/os.html">11.x</a></li> <li><a href="https://nodejs.org/docs/latest-v10.x/api/os.html">10.x</a></li> <li><a href="https://nodejs.org/docs/latest-v9.x/api/os.html">9.x</a></li> <li><a href="https://nodejs.org/docs/latest-v8.x/api/os.html">8.x</a></li> <li><a href="https://nodejs.org/docs/latest-v7.x/api/os.html">7.x</a></li> <li><a href="https://nodejs.org/docs/latest-v6.x/api/os.html">6.x</a></li> <li><a href="https://nodejs.org/docs/latest-v5.x/api/os.html">5.x</a></li> <li><a href="https://nodejs.org/docs/latest-v4.x/api/os.html">4.x</a></li> <li><a href="https://nodejs.org/docs/latest-v0.12.x/api/os.html">0.12.x</a></li> <li><a href="https://nodejs.org/docs/latest-v0.10.x/api/os.html">0.10.x</a></li></ol></div> </li> <li class="picker-header"> <a href="#options-picker" aria-controls="options-picker"> <span class="picker-arrow"></span> Options </a> <div class="picker" tabindex="-1"> <ul id="options-picker"> <li> <a href="all.html">View on single page</a> </li> <li> <a href="os.json">View as JSON</a> </li> <li class="edit_on_github"><a href="https://github.com/nodejs/node/edit/main/doc/api/os.md">Edit on GitHub</a></li> </ul> </div> </li> </ul> </div> <hr> </header> <details role="navigation" id="toc" open><summary>Table of contents</summary><ul> <li><span class="stability_2"><a href="#os">OS</a></span> <ul> <li><a href="#oseol"><code>os.EOL</code></a></li> <li><a href="#osavailableparallelism"><code>os.availableParallelism()</code></a></li> <li><a href="#osarch"><code>os.arch()</code></a></li> <li><a href="#osconstants"><code>os.constants</code></a></li> <li><a href="#oscpus"><code>os.cpus()</code></a></li> <li><a href="#osdevnull"><code>os.devNull</code></a></li> <li><a href="#osendianness"><code>os.endianness()</code></a></li> <li><a href="#osfreemem"><code>os.freemem()</code></a></li> <li><a href="#osgetprioritypid"><code>os.getPriority([pid])</code></a></li> <li><a href="#oshomedir"><code>os.homedir()</code></a></li> <li><a href="#oshostname"><code>os.hostname()</code></a></li> <li><a href="#osloadavg"><code>os.loadavg()</code></a></li> <li><a href="#osmachine"><code>os.machine()</code></a></li> <li><a href="#osnetworkinterfaces"><code>os.networkInterfaces()</code></a></li> <li><a href="#osplatform"><code>os.platform()</code></a></li> <li><a href="#osrelease"><code>os.release()</code></a></li> <li><a href="#ossetprioritypid-priority"><code>os.setPriority([pid, ]priority)</code></a></li> <li><a href="#ostmpdir"><code>os.tmpdir()</code></a></li> <li><a href="#ostotalmem"><code>os.totalmem()</code></a></li> <li><a href="#ostype"><code>os.type()</code></a></li> <li><a href="#osuptime"><code>os.uptime()</code></a></li> <li><a href="#osuserinfooptions"><code>os.userInfo([options])</code></a></li> <li><a href="#osversion"><code>os.version()</code></a></li> <li><a href="#os-constants">OS constants</a> <ul> <li><a href="#signal-constants">Signal constants</a></li> <li><a href="#error-constants">Error constants</a> <ul> <li><a href="#posix-error-constants">POSIX error constants</a></li> <li><a href="#windows-specific-error-constants">Windows-specific error constants</a></li> </ul> </li> <li><a href="#dlopen-constants">dlopen constants</a></li> <li><a href="#priority-constants">Priority constants</a></li> <li><a href="#libuv-constants">libuv constants</a></li> </ul> </li> </ul> </li> </ul></details> <div role="main" id="apicontent"> <h2>OS<span><a class="mark" href="#os" id="os">#</a></span><a aria-hidden="true" class="legacy" id="os_os"></a></h2> <p></p><div class="api_stability api_stability_2"><a href="documentation.html#stability-index">Stability: 2</a> - Stable</div><p></p> <p><strong>Source Code:</strong> <a href="https://github.com/nodejs/node/blob/v22.22.0/lib/os.js">lib/os.js</a></p> <p>The <code>node:os</code> module provides operating system-related utility methods and properties. It can be accessed using:</p> <pre class="with-30-chars"><input class="js-flavor-toggle" type="checkbox" checked aria-label="Show modern ES modules syntax"><code class="language-js mjs"><span class="hljs-keyword">import</span> os <span class="hljs-keyword">from</span> <span class="hljs-string">'node:os'</span>;</code><code class="language-js cjs"><span class="hljs-keyword">const</span> os = <span class="hljs-built_in">require</span>(<span class="hljs-string">'node:os'</span>);</code><button class="copy-button">copy</button></pre> <section><h3><code>os.EOL</code><span><a class="mark" href="#oseol" id="oseol">#</a></span><a aria-hidden="true" class="legacy" id="os_os_eol"></a></h3> <div class="api_metadata"> <span>Added in: v0.7.8</span> </div> <ul> <li>Type: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a></li> </ul> <p>The operating system-specific end-of-line marker.</p> <ul> <li><code>\n</code> on POSIX</li> <li><code>\r\n</code> on Windows</li> </ul> </section><section><h3><code>os.availableParallelism()</code><span><a class="mark" href="#osavailableparallelism" id="osavailableparallelism">#</a></span><a aria-hidden="true" class="legacy" id="os_os_availableparallelism"></a></h3> <div class="api_metadata"> <span>Added in: v19.4.0, v18.14.0</span> </div> <ul> <li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a></li> </ul> <p>Returns an estimate of the default amount of parallelism a program should use. Always returns a value greater than zero.</p> <p>This function is a small wrapper about libuv's <a href="https://docs.libuv.org/en/v1.x/misc.html#c.uv_available_parallelism"><code>uv_available_parallelism()</code></a>.</p> </section><section><h3><code>os.arch()</code><span><a class="mark" href="#osarch" id="osarch">#</a></span><a aria-hidden="true" class="legacy" id="os_os_arch"></a></h3> <div class="api_metadata"> <span>Added in: v0.5.0</span> </div> <ul> <li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a></li> </ul> <p>Returns the operating system CPU architecture for which the Node.js binary was compiled. Possible values are <code>'arm'</code>, <code>'arm64'</code>, <code>'ia32'</code>, <code>'loong64'</code>, <code>'mips'</code>, <code>'mipsel'</code>, <code>'ppc'</code>, <code>'ppc64'</code>, <code>'riscv64'</code>, <code>'s390'</code>, <code>'s390x'</code>, and <code>'x64'</code>.</p> <p>The return value is equivalent to <a href="process.html#processarch"><code>process.arch</code></a>.</p> </section><section><h3><code>os.constants</code><span><a class="mark" href="#osconstants" id="osconstants">#</a></span><a aria-hidden="true" class="legacy" id="os_os_constants"></a></h3> <div class="api_metadata"> <span>Added in: v6.3.0</span> </div> <ul> <li>Type: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a></li> </ul> <p>Contains commonly used operating system-specific constants for error codes, process signals, and so on. The specific constants defined are described in <a href="#os-constants">OS constants</a>.</p> </section><section><h3><code>os.cpus()</code><span><a class="mark" href="#oscpus" id="oscpus">#</a></span><a aria-hidden="true" class="legacy" id="os_os_cpus"></a></h3> <div class="api_metadata"> <span>Added in: v0.3.3</span> </div> <ul> <li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object[]></a></li> </ul> <p>Returns an array of objects containing information about each logical CPU core. The array will be empty if no CPU information is available, such as if the <code>/proc</code> file system is unavailable.</p> <p>The properties included on each object include:</p> <ul> <li><code>model</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a></li> <li><code>speed</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a> (in MHz)</li> <li><code>times</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> <ul> <li><code>user</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a> The number of milliseconds the CPU has spent in user mode.</li> <li><code>nice</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a> The number of milliseconds the CPU has spent in nice mode.</li> <li><code>sys</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a> The number of milliseconds the CPU has spent in sys mode.</li> <li><code>idle</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a> The number of milliseconds the CPU has spent in idle mode.</li> <li><code>irq</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a> The number of milliseconds the CPU has spent in irq mode.</li> </ul> </li> </ul> <!-- eslint-disable @stylistic/js/semi --> <pre><code class="language-js">[ { <span class="hljs-attr">model</span>: <span class="hljs-string">'Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz'</span>, <span class="hljs-attr">speed</span>: <span class="hljs-number">2926</span>, <span class="hljs-attr">times</span>: { <span class="hljs-attr">user</span>: <span class="hljs-number">252020</span>, <span class="hljs-attr">nice</span>: <span class="hljs-number">0</span>, <span class="hljs-attr">sys</span>: <span class="hljs-number">30340</span>, <span class="hljs-attr">idle</span>: <span class="hljs-number">1070356870</span>, <span class="hljs-attr">irq</span>: <span class="hljs-number">0</span>, }, }, { <span class="hljs-attr">model</span>: <span class="hljs-string">'Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz'</span>, <span class="hljs-attr">speed</span>: <span class="hljs-number">2926</span>, <span class="hljs-attr">times</span>: { <span class="hljs-attr">user</span>: <span class="hljs-number">306960</span>, <span class="hljs-attr">nice</span>: <span class="hljs-number">0</span>, <span class="hljs-attr">sys</span>: <span class="hljs-number">26980</span>, <span class="hljs-attr">idle</span>: <span class="hljs-number">1071569080</span>, <span class="hljs-attr">irq</span>: <span class="hljs-number">0</span>, }, }, { <span class="hljs-attr">model</span>: <span class="hljs-string">'Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz'</span>, <span class="hljs-attr">speed</span>: <span class="hljs-number">2926</span>, <span class="hljs-attr">times</span>: { <span class="hljs-attr">user</span>: <span class="hljs-number">248450</span>, <span class="hljs-attr">nice</span>: <span class="hljs-number">0</span>, <span class="hljs-attr">sys</span>: <span class="hljs-number">21750</span>, <span class="hljs-attr">idle</span>: <span class="hljs-number">1070919370</span>, <span class="hljs-attr">irq</span>: <span class="hljs-number">0</span>, }, }, { <span class="hljs-attr">model</span>: <span class="hljs-string">'Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz'</span>, <span class="hljs-attr">speed</span>: <span class="hljs-number">2926</span>, <span class="hljs-attr">times</span>: { <span class="hljs-attr">user</span>: <span class="hljs-number">256880</span>, <span class="hljs-attr">nice</span>: <span class="hljs-number">0</span>, <span class="hljs-attr">sys</span>: <span class="hljs-number">19430</span>, <span class="hljs-attr">idle</span>: <span class="hljs-number">1070905480</span>, <span class="hljs-attr">irq</span>: <span class="hljs-number">20</span>, }, }, ]</code> <button class="copy-button">copy</button></pre> <p><code>nice</code> values are POSIX-only. On Windows, the <code>nice</code> values of all processors are always 0.</p> <p><code>os.cpus().length</code> should not be used to calculate the amount of parallelism available to an application. Use <a href="#osavailableparallelism"><code>os.availableParallelism()</code></a> for this purpose.</p> </section><section><h3><code>os.devNull</code><span><a class="mark" href="#osdevnull" id="osdevnull">#</a></span><a aria-hidden="true" class="legacy" id="os_os_devnull"></a></h3> <div class="api_metadata"> <span>Added in: v16.3.0, v14.18.0</span> </div> <ul> <li>Type: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a></li> </ul> <p>The platform-specific file path of the null device.</p> <ul> <li><code>\\.\nul</code> on Windows</li> <li><code>/dev/null</code> on POSIX</li> </ul> </section><section><h3><code>os.endianness()</code><span><a class="mark" href="#osendianness" id="osendianness">#</a></span><a aria-hidden="true" class="legacy" id="os_os_endianness"></a></h3> <div class="api_metadata"> <span>Added in: v0.9.4</span> </div> <ul> <li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a></li> </ul> <p>Returns a string identifying the endianness of the CPU for which the Node.js binary was compiled.</p> <p>Possible values are <code>'BE'</code> for big endian and <code>'LE'</code> for little endian.</p> </section><section><h3><code>os.freemem()</code><span><a class="mark" href="#osfreemem" id="osfreemem">#</a></span><a aria-hidden="true" class="legacy" id="os_os_freemem"></a></h3> <div class="api_metadata"> <span>Added in: v0.3.3</span> </div> <ul> <li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a></li> </ul> <p>Returns the amount of free system memory in bytes as an integer.</p> </section><section><h3><code>os.getPriority([pid])</code><span><a class="mark" href="#osgetprioritypid" id="osgetprioritypid">#</a></span><a aria-hidden="true" class="legacy" id="os_os_getpriority_pid"></a></h3> <div class="api_metadata"> <span>Added in: v10.10.0</span> </div> <ul> <li><code>pid</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> The process ID to retrieve scheduling priority for. <strong>Default:</strong> <code>0</code>.</li> <li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a></li> </ul> <p>Returns the scheduling priority for the process specified by <code>pid</code>. If <code>pid</code> is not provided or is <code>0</code>, the priority of the current process is returned.</p> </section><section><h3><code>os.homedir()</code><span><a class="mark" href="#oshomedir" id="oshomedir">#</a></span><a aria-hidden="true" class="legacy" id="os_os_homedir"></a></h3> <div class="api_metadata"> <span>Added in: v2.3.0</span> </div> <ul> <li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a></li> </ul> <p>Returns the string path of the current user's home directory.</p> <p>On POSIX, it uses the <code>$HOME</code> environment variable if defined. Otherwise it uses the <a href="https://en.wikipedia.org/wiki/User_identifier#Effective_user_ID">effective UID</a> to look up the user's home directory.</p> <p>On Windows, it uses the <code>USERPROFILE</code> environment variable if defined. Otherwise it uses the path to the profile directory of the current user.</p> </section><section><h3><code>os.hostname()</code><span><a class="mark" href="#oshostname" id="oshostname">#</a></span><a aria-hidden="true" class="legacy" id="os_os_hostname"></a></h3> <div class="api_metadata"> <span>Added in: v0.3.3</span> </div> <ul> <li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a></li> </ul> <p>Returns the host name of the operating system as a string.</p> </section><section><h3><code>os.loadavg()</code><span><a class="mark" href="#osloadavg" id="osloadavg">#</a></span><a aria-hidden="true" class="legacy" id="os_os_loadavg"></a></h3> <div class="api_metadata"> <span>Added in: v0.3.3</span> </div> <ul> <li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number[]></a></li> </ul> <p>Returns an array containing the 1, 5, and 15 minute load averages.</p> <p>The load average is a measure of system activity calculated by the operating system and expressed as a fractional number.</p> <p>The load average is a Unix-specific concept. On Windows, the return value is always <code>[0, 0, 0]</code>.</p> </section><section><h3><code>os.machine()</code><span><a class="mark" href="#osmachine" id="osmachine">#</a></span><a aria-hidden="true" class="legacy" id="os_os_machine"></a></h3> <div class="api_metadata"> <span>Added in: v18.9.0, v16.18.0</span> </div> <ul> <li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a></li> </ul> <p>Returns the machine type as a string, such as <code>arm</code>, <code>arm64</code>, <code>aarch64</code>, <code>mips</code>, <code>mips64</code>, <code>ppc64</code>, <code>ppc64le</code>, <code>s390</code>, <code>s390x</code>, <code>i386</code>, <code>i686</code>, <code>x86_64</code>.</p> <p>On POSIX systems, the machine type is determined by calling <a href="https://linux.die.net/man/3/uname"><code>uname(3)</code></a>. On Windows, <code>RtlGetVersion()</code> is used, and if it is not available, <code>GetVersionExW()</code> will be used. See <a href="https://en.wikipedia.org/wiki/Uname#Examples">https://en.wikipedia.org/wiki/Uname#Examples</a> for more information.</p> </section><section><h3><code>os.networkInterfaces()</code><span><a class="mark" href="#osnetworkinterfaces" id="osnetworkinterfaces">#</a></span><a aria-hidden="true" class="legacy" id="os_os_networkinterfaces"></a></h3> <div class="api_metadata"> <details class="changelog"><summary>History</summary> <table> <tbody><tr><th>Version</th><th>Changes</th></tr> <tr><td>v18.4.0</td> <td><p>The <code>family</code> property now returns a string instead of a number.</p></td></tr> <tr><td>v18.0.0</td> <td><p>The <code>family</code> property now returns a number instead of a string.</p></td></tr> <tr><td>v0.6.0</td> <td><p><span>Added in: v0.6.0</span></p></td></tr> </tbody></table> </details> </div> <ul> <li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a></li> </ul> <p>Returns an object containing network interfaces that have been assigned a network address.</p> <p>Each key on the returned object identifies a network interface. The associated value is an array of objects that each describe an assigned network address.</p> <p>The properties available on the assigned network address object include:</p> <ul> <li><code>address</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> The assigned IPv4 or IPv6 address</li> <li><code>netmask</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> The IPv4 or IPv6 network mask</li> <li><code>family</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> Either <code>IPv4</code> or <code>IPv6</code></li> <li><code>mac</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> The MAC address of the network interface</li> <li><code>internal</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Boolean_type" class="type"><boolean></a> <code>true</code> if the network interface is a loopback or similar interface that is not remotely accessible; otherwise <code>false</code></li> <li><code>scopeid</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><number></a> The numeric IPv6 scope ID (only specified when <code>family</code> is <code>IPv6</code>)</li> <li><code>cidr</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> The assigned IPv4 or IPv6 address with the routing prefix in CIDR notation. If the <code>netmask</code> is invalid, this property is set to <code>null</code>.</li> </ul> <!-- eslint-skip --> <pre><code class="language-js">{ <span class="hljs-attr">lo</span>: [ { <span class="hljs-attr">address</span>: <span class="hljs-string">'127.0.0.1'</span>, <span class="hljs-attr">netmask</span>: <span class="hljs-string">'255.0.0.0'</span>, <span class="hljs-attr">family</span>: <span class="hljs-string">'IPv4'</span>, <span class="hljs-attr">mac</span>: <span class="hljs-string">'00:00:00:00:00:00'</span>, <span class="hljs-attr">internal</span>: <span class="hljs-literal">true</span>, <span class="hljs-attr">cidr</span>: <span class="hljs-string">'127.0.0.1/8'</span> }, { <span class="hljs-attr">address</span>: <span class="hljs-string">'::1'</span>, <span class="hljs-attr">netmask</span>: <span class="hljs-string">'ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff'</span>, <span class="hljs-attr">family</span>: <span class="hljs-string">'IPv6'</span>, <span class="hljs-attr">mac</span>: <span class="hljs-string">'00:00:00:00:00:00'</span>, <span class="hljs-attr">scopeid</span>: <span class="hljs-number">0</span>, <span class="hljs-attr">internal</span>: <span class="hljs-literal">true</span>, <span class="hljs-attr">cidr</span>: <span class="hljs-string">'::1/128'</span> } ], <span class="hljs-attr">eth0</span>: [ { <span class="hljs-attr">address</span>: <span class="hljs-string">'192.168.1.108'</span>, <span class="hljs-attr">netmask</span>: <span class="hljs-string">'255.255.255.0'</span>, <span class="hljs-attr">family</span>: <span class="hljs-string">'IPv4'</span>, <span class="hljs-attr">mac</span>: <span class="hljs-string">'01:02:03:0a:0b:0c'</span>, <span class="hljs-attr">internal</span>: <span class="hljs-literal">false</span>, <span class="hljs-attr">cidr</span>: <span class="hljs-string">'192.168.1.108/24'</span> }, { <span class="hljs-attr">address</span>: <span class="hljs-string">'fe80::a00:27ff:fe4e:66a1'</span>, <span class="hljs-attr">netmask</span>: <span class="hljs-string">'ffff:ffff:ffff:ffff::'</span>, <span class="hljs-attr">family</span>: <span class="hljs-string">'IPv6'</span>, <span class="hljs-attr">mac</span>: <span class="hljs-string">'01:02:03:0a:0b:0c'</span>, <span class="hljs-attr">scopeid</span>: <span class="hljs-number">1</span>, <span class="hljs-attr">internal</span>: <span class="hljs-literal">false</span>, <span class="hljs-attr">cidr</span>: <span class="hljs-string">'fe80::a00:27ff:fe4e:66a1/64'</span> } ] }</code> <button class="copy-button">copy</button></pre> </section><section><h3><code>os.platform()</code><span><a class="mark" href="#osplatform" id="osplatform">#</a></span><a aria-hidden="true" class="legacy" id="os_os_platform"></a></h3> <div class="api_metadata"> <span>Added in: v0.5.0</span> </div> <ul> <li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a></li> </ul> <p>Returns a string identifying the operating system platform for which the Node.js binary was compiled. The value is set at compile time. Possible values are <code>'aix'</code>, <code>'darwin'</code>, <code>'freebsd'</code>,<code>'linux'</code>, <code>'openbsd'</code>, <code>'sunos'</code>, and <code>'win32'</code>.</p> <p>The return value is equivalent to <a href="process.html#processplatform"><code>process.platform</code></a>.</p> <p>The value <code>'android'</code> may also be returned if Node.js is built on the Android operating system. <a href="https://github.com/nodejs/node/blob/HEAD/BUILDING.md#android">Android support is experimental</a>.</p> </section><section><h3><code>os.release()</code><span><a class="mark" href="#osrelease" id="osrelease">#</a></span><a aria-hidden="true" class="legacy" id="os_os_release"></a></h3> <div class="api_metadata"> <span>Added in: v0.3.3</span> </div> <ul> <li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a></li> </ul> <p>Returns the operating system as a string.</p> <p>On POSIX systems, the operating system release is determined by calling <a href="https://linux.die.net/man/3/uname"><code>uname(3)</code></a>. On Windows, <code>GetVersionExW()</code> is used. See <a href="https://en.wikipedia.org/wiki/Uname#Examples">https://en.wikipedia.org/wiki/Uname#Examples</a> for more information.</p> </section><section><h3><code>os.setPriority([pid, ]priority)</code><span><a class="mark" href="#ossetprioritypid-priority" id="ossetprioritypid-priority">#</a></span><a aria-hidden="true" class="legacy" id="os_os_setpriority_pid_priority"></a></h3> <div class="api_metadata"> <span>Added in: v10.10.0</span> </div> <ul> <li><code>pid</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> The process ID to set scheduling priority for. <strong>Default:</strong> <code>0</code>.</li> <li><code>priority</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a> The scheduling priority to assign to the process.</li> </ul> <p>Attempts to set the scheduling priority for the process specified by <code>pid</code>. If <code>pid</code> is not provided or is <code>0</code>, the process ID of the current process is used.</p> <p>The <code>priority</code> input must be an integer between <code>-20</code> (high priority) and <code>19</code> (low priority). Due to differences between Unix priority levels and Windows priority classes, <code>priority</code> is mapped to one of six priority constants in <code>os.constants.priority</code>. When retrieving a process priority level, this range mapping may cause the return value to be slightly different on Windows. To avoid confusion, set <code>priority</code> to one of the priority constants.</p> <p>On Windows, setting priority to <code>PRIORITY_HIGHEST</code> requires elevated user privileges. Otherwise the set priority will be silently reduced to <code>PRIORITY_HIGH</code>.</p> </section><section><h3><code>os.tmpdir()</code><span><a class="mark" href="#ostmpdir" id="ostmpdir">#</a></span><a aria-hidden="true" class="legacy" id="os_os_tmpdir"></a></h3> <div class="api_metadata"> <details class="changelog"><summary>History</summary> <table> <tbody><tr><th>Version</th><th>Changes</th></tr> <tr><td>v2.0.0</td> <td><p>This function is now cross-platform consistent and no longer returns a path with a trailing slash on any platform.</p></td></tr> <tr><td>v0.9.9</td> <td><p><span>Added in: v0.9.9</span></p></td></tr> </tbody></table> </details> </div> <ul> <li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a></li> </ul> <p>Returns the operating system's default directory for temporary files as a string.</p> <p>On Windows, the result can be overridden by <code>TEMP</code> and <code>TMP</code> environment variables, and <code>TEMP</code> takes precedence over <code>TMP</code>. If neither is set, it defaults to <code>%SystemRoot%\temp</code> or <code>%windir%\temp</code>.</p> <p>On non-Windows platforms, <code>TMPDIR</code>, <code>TMP</code> and <code>TEMP</code> environment variables will be checked to override the result of this method, in the described order. If none of them is set, it defaults to <code>/tmp</code>.</p> <p>Some operating system distributions would either configure <code>TMPDIR</code> (non-Windows) or <code>TEMP</code> and <code>TMP</code> (Windows) by default without additional configurations by the system administrators. The result of <code>os.tmpdir()</code> typically reflects the system preference unless it's explicitly overridden by the users.</p> </section><section><h3><code>os.totalmem()</code><span><a class="mark" href="#ostotalmem" id="ostotalmem">#</a></span><a aria-hidden="true" class="legacy" id="os_os_totalmem"></a></h3> <div class="api_metadata"> <span>Added in: v0.3.3</span> </div> <ul> <li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a></li> </ul> <p>Returns the total amount of system memory in bytes as an integer.</p> </section><section><h3><code>os.type()</code><span><a class="mark" href="#ostype" id="ostype">#</a></span><a aria-hidden="true" class="legacy" id="os_os_type"></a></h3> <div class="api_metadata"> <span>Added in: v0.3.3</span> </div> <ul> <li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a></li> </ul> <p>Returns the operating system name as returned by <a href="https://linux.die.net/man/3/uname"><code>uname(3)</code></a>. For example, it returns <code>'Linux'</code> on Linux, <code>'Darwin'</code> on macOS, and <code>'Windows_NT'</code> on Windows.</p> <p>See <a href="https://en.wikipedia.org/wiki/Uname#Examples">https://en.wikipedia.org/wiki/Uname#Examples</a> for additional information about the output of running <a href="https://linux.die.net/man/3/uname"><code>uname(3)</code></a> on various operating systems.</p> </section><section><h3><code>os.uptime()</code><span><a class="mark" href="#osuptime" id="osuptime">#</a></span><a aria-hidden="true" class="legacy" id="os_os_uptime"></a></h3> <div class="api_metadata"> <details class="changelog"><summary>History</summary> <table> <tbody><tr><th>Version</th><th>Changes</th></tr> <tr><td>v10.0.0</td> <td><p>The result of this function no longer contains a fraction component on Windows.</p></td></tr> <tr><td>v0.3.3</td> <td><p><span>Added in: v0.3.3</span></p></td></tr> </tbody></table> </details> </div> <ul> <li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#Number_type" class="type"><integer></a></li> </ul> <p>Returns the system uptime in number of seconds.</p> </section><section><h3><code>os.userInfo([options])</code><span><a class="mark" href="#osuserinfooptions" id="osuserinfooptions">#</a></span><a aria-hidden="true" class="legacy" id="os_os_userinfo_options"></a></h3> <div class="api_metadata"> <span>Added in: v6.0.0</span> </div> <ul> <li><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a> <ul> <li><code>encoding</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a> Character encoding used to interpret resulting strings. If <code>encoding</code> is set to <code>'buffer'</code>, the <code>username</code>, <code>shell</code>, and <code>homedir</code> values will be <code>Buffer</code> instances. <strong>Default:</strong> <code>'utf8'</code>.</li> </ul> </li> <li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a></li> </ul> <p>Returns information about the currently effective user. On POSIX platforms, this is typically a subset of the password file. The returned object includes the <code>username</code>, <code>uid</code>, <code>gid</code>, <code>shell</code>, and <code>homedir</code>. On Windows, the <code>uid</code> and <code>gid</code> fields are <code>-1</code>, and <code>shell</code> is <code>null</code>.</p> <p>The value of <code>homedir</code> returned by <code>os.userInfo()</code> is provided by the operating system. This differs from the result of <code>os.homedir()</code>, which queries environment variables for the home directory before falling back to the operating system response.</p> <p>Throws a <a href="errors.html#class-systemerror"><code>SystemError</code></a> if a user has no <code>username</code> or <code>homedir</code>.</p> </section><section><h3><code>os.version()</code><span><a class="mark" href="#osversion" id="osversion">#</a></span><a aria-hidden="true" class="legacy" id="os_os_version"></a></h3> <div class="api_metadata"> <span>Added in: v13.11.0, v12.17.0</span> </div> <ul> <li>Returns: <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a></li> </ul> <p>Returns a string identifying the kernel version.</p> <p>On POSIX systems, the operating system release is determined by calling <a href="https://linux.die.net/man/3/uname"><code>uname(3)</code></a>. On Windows, <code>RtlGetVersion()</code> is used, and if it is not available, <code>GetVersionExW()</code> will be used. See <a href="https://en.wikipedia.org/wiki/Uname#Examples">https://en.wikipedia.org/wiki/Uname#Examples</a> for more information.</p> </section><section><h3>OS constants<span><a class="mark" href="#os-constants" id="os-constants">#</a></span><a aria-hidden="true" class="legacy" id="os_os_constants_1"></a></h3> <p>The following constants are exported by <code>os.constants</code>.</p> <p>Not all constants will be available on every operating system.</p> <div> <h4>Signal constants<span><a class="mark" href="#signal-constants" id="signal-constants">#</a></span><a aria-hidden="true" class="legacy" id="os_signal_constants"></a></h4> <div class="api_metadata"> <details class="changelog"><summary>History</summary> <table> <tbody><tr><th>Version</th><th>Changes</th></tr> <tr><td>v5.11.0</td> <td><p>Added support for <code>SIGINFO</code>.</p></td></tr> </tbody></table> </details> </div> <p>The following signal constants are exported by <code>os.constants.signals</code>.</p> <table> <tbody><tr> <th>Constant</th> <th>Description</th> </tr> <tr> <td><code>SIGHUP</code></td> <td>Sent to indicate when a controlling terminal is closed or a parent process exits.</td> </tr> <tr> <td><code>SIGINT</code></td> <td>Sent to indicate when a user wishes to interrupt a process (<kbd>Ctrl</kbd>+<kbd>C</kbd>).</td> </tr> <tr> <td><code>SIGQUIT</code></td> <td>Sent to indicate when a user wishes to terminate a process and perform a core dump.</td> </tr> <tr> <td><code>SIGILL</code></td> <td>Sent to a process to notify that it has attempted to perform an illegal, malformed, unknown, or privileged instruction.</td> </tr> <tr> <td><code>SIGTRAP</code></td> <td>Sent to a process when an exception has occurred.</td> </tr> <tr> <td><code>SIGABRT</code></td> <td>Sent to a process to request that it abort.</td> </tr> <tr> <td><code>SIGIOT</code></td> <td>Synonym for <code>SIGABRT</code></td> </tr> <tr> <td><code>SIGBUS</code></td> <td>Sent to a process to notify that it has caused a bus error.</td> </tr> <tr> <td><code>SIGFPE</code></td> <td>Sent to a process to notify that it has performed an illegal arithmetic operation.</td> </tr> <tr> <td><code>SIGKILL</code></td> <td>Sent to a process to terminate it immediately.</td> </tr> <tr> <td><code>SIGUSR1</code> <code>SIGUSR2</code></td> <td>Sent to a process to identify user-defined conditions.</td> </tr> <tr> <td><code>SIGSEGV</code></td> <td>Sent to a process to notify of a segmentation fault.</td> </tr> <tr> <td><code>SIGPIPE</code></td> <td>Sent to a process when it has attempted to write to a disconnected pipe.</td> </tr> <tr> <td><code>SIGALRM</code></td> <td>Sent to a process when a system timer elapses.</td> </tr> <tr> <td><code>SIGTERM</code></td> <td>Sent to a process to request termination.</td> </tr> <tr> <td><code>SIGCHLD</code></td> <td>Sent to a process when a child process terminates.</td> </tr> <tr> <td><code>SIGSTKFLT</code></td> <td>Sent to a process to indicate a stack fault on a coprocessor.</td> </tr> <tr> <td><code>SIGCONT</code></td> <td>Sent to instruct the operating system to continue a paused process.</td> </tr> <tr> <td><code>SIGSTOP</code></td> <td>Sent to instruct the operating system to halt a process.</td> </tr> <tr> <td><code>SIGTSTP</code></td> <td>Sent to a process to request it to stop.</td> </tr> <tr> <td><code>SIGBREAK</code></td> <td>Sent to indicate when a user wishes to interrupt a process.</td> </tr> <tr> <td><code>SIGTTIN</code></td> <td>Sent to a process when it reads from the TTY while in the background.</td> </tr> <tr> <td><code>SIGTTOU</code></td> <td>Sent to a process when it writes to the TTY while in the background.</td> </tr> <tr> <td><code>SIGURG</code></td> <td>Sent to a process when a socket has urgent data to read.</td> </tr> <tr> <td><code>SIGXCPU</code></td> <td>Sent to a process when it has exceeded its limit on CPU usage.</td> </tr> <tr> <td><code>SIGXFSZ</code></td> <td>Sent to a process when it grows a file larger than the maximum allowed.</td> </tr> <tr> <td><code>SIGVTALRM</code></td> <td>Sent to a process when a virtual timer has elapsed.</td> </tr> <tr> <td><code>SIGPROF</code></td> <td>Sent to a process when a system timer has elapsed.</td> </tr> <tr> <td><code>SIGWINCH</code></td> <td>Sent to a process when the controlling terminal has changed its size.</td> </tr> <tr> <td><code>SIGIO</code></td> <td>Sent to a process when I/O is available.</td> </tr> <tr> <td><code>SIGPOLL</code></td> <td>Synonym for <code>SIGIO</code></td> </tr> <tr> <td><code>SIGLOST</code></td> <td>Sent to a process when a file lock has been lost.</td> </tr> <tr> <td><code>SIGPWR</code></td> <td>Sent to a process to notify of a power failure.</td> </tr> <tr> <td><code>SIGINFO</code></td> <td>Synonym for <code>SIGPWR</code></td> </tr> <tr> <td><code>SIGSYS</code></td> <td>Sent to a process to notify of a bad argument.</td> </tr> <tr> <td><code>SIGUNUSED</code></td> <td>Synonym for <code>SIGSYS</code></td> </tr> </tbody></table> </div><div> <h4>Error constants<span><a class="mark" href="#error-constants" id="error-constants">#</a></span><a aria-hidden="true" class="legacy" id="os_error_constants"></a></h4> <p>The following error constants are exported by <code>os.constants.errno</code>.</p> <div> <h5>POSIX error constants<span><a class="mark" href="#posix-error-constants" id="posix-error-constants">#</a></span><a aria-hidden="true" class="legacy" id="os_posix_error_constants"></a></h5> <table> <tbody><tr> <th>Constant</th> <th>Description</th> </tr> <tr> <td><code>E2BIG</code></td> <td>Indicates that the list of arguments is longer than expected.</td> </tr> <tr> <td><code>EACCES</code></td> <td>Indicates that the operation did not have sufficient permissions.</td> </tr> <tr> <td><code>EADDRINUSE</code></td> <td>Indicates that the network address is already in use.</td> </tr> <tr> <td><code>EADDRNOTAVAIL</code></td> <td>Indicates that the network address is currently unavailable for use.</td> </tr> <tr> <td><code>EAFNOSUPPORT</code></td> <td>Indicates that the network address family is not supported.</td> </tr> <tr> <td><code>EAGAIN</code></td> <td>Indicates that there is no data available and to try the operation again later.</td> </tr> <tr> <td><code>EALREADY</code></td> <td>Indicates that the socket already has a pending connection in progress.</td> </tr> <tr> <td><code>EBADF</code></td> <td>Indicates that a file descriptor is not valid.</td> </tr> <tr> <td><code>EBADMSG</code></td> <td>Indicates an invalid data message.</td> </tr> <tr> <td><code>EBUSY</code></td> <td>Indicates that a device or resource is busy.</td> </tr> <tr> <td><code>ECANCELED</code></td> <td>Indicates that an operation was canceled.</td> </tr> <tr> <td><code>ECHILD</code></td> <td>Indicates that there are no child processes.</td> </tr> <tr> <td><code>ECONNABORTED</code></td> <td>Indicates that the network connection has been aborted.</td> </tr> <tr> <td><code>ECONNREFUSED</code></td> <td>Indicates that the network connection has been refused.</td> </tr> <tr> <td><code>ECONNRESET</code></td> <td>Indicates that the network connection has been reset.</td> </tr> <tr> <td><code>EDEADLK</code></td> <td>Indicates that a resource deadlock has been avoided.</td> </tr> <tr> <td><code>EDESTADDRREQ</code></td> <td>Indicates that a destination address is required.</td> </tr> <tr> <td><code>EDOM</code></td> <td>Indicates that an argument is out of the domain of the function.</td> </tr> <tr> <td><code>EDQUOT</code></td> <td>Indicates that the disk quota has been exceeded.</td> </tr> <tr> <td><code>EEXIST</code></td> <td>Indicates that the file already exists.</td> </tr> <tr> <td><code>EFAULT</code></td> <td>Indicates an invalid pointer address.</td> </tr> <tr> <td><code>EFBIG</code></td> <td>Indicates that the file is too large.</td> </tr> <tr> <td><code>EHOSTUNREACH</code></td> <td>Indicates that the host is unreachable.</td> </tr> <tr> <td><code>EIDRM</code></td> <td>Indicates that the identifier has been removed.</td> </tr> <tr> <td><code>EILSEQ</code></td> <td>Indicates an illegal byte sequence.</td> </tr> <tr> <td><code>EINPROGRESS</code></td> <td>Indicates that an operation is already in progress.</td> </tr> <tr> <td><code>EINTR</code></td> <td>Indicates that a function call was interrupted.</td> </tr> <tr> <td><code>EINVAL</code></td> <td>Indicates that an invalid argument was provided.</td> </tr> <tr> <td><code>EIO</code></td> <td>Indicates an otherwise unspecified I/O error.</td> </tr> <tr> <td><code>EISCONN</code></td> <td>Indicates that the socket is connected.</td> </tr> <tr> <td><code>EISDIR</code></td> <td>Indicates that the path is a directory.</td> </tr> <tr> <td><code>ELOOP</code></td> <td>Indicates too many levels of symbolic links in a path.</td> </tr> <tr> <td><code>EMFILE</code></td> <td>Indicates that there are too many open files.</td> </tr> <tr> <td><code>EMLINK</code></td> <td>Indicates that there are too many hard links to a file.</td> </tr> <tr> <td><code>EMSGSIZE</code></td> <td>Indicates that the provided message is too long.</td> </tr> <tr> <td><code>EMULTIHOP</code></td> <td>Indicates that a multihop was attempted.</td> </tr> <tr> <td><code>ENAMETOOLONG</code></td> <td>Indicates that the filename is too long.</td> </tr> <tr> <td><code>ENETDOWN</code></td> <td>Indicates that the network is down.</td> </tr> <tr> <td><code>ENETRESET</code></td> <td>Indicates that the connection has been aborted by the network.</td> </tr> <tr> <td><code>ENETUNREACH</code></td> <td>Indicates that the network is unreachable.</td> </tr> <tr> <td><code>ENFILE</code></td> <td>Indicates too many open files in the system.</td> </tr> <tr> <td><code>ENOBUFS</code></td> <td>Indicates that no buffer space is available.</td> </tr> <tr> <td><code>ENODATA</code></td> <td>Indicates that no message is available on the stream head read queue.</td> </tr> <tr> <td><code>ENODEV</code></td> <td>Indicates that there is no such device.</td> </tr> <tr> <td><code>ENOENT</code></td> <td>Indicates that there is no such file or directory.</td> </tr> <tr> <td><code>ENOEXEC</code></td> <td>Indicates an exec format error.</td> </tr> <tr> <td><code>ENOLCK</code></td> <td>Indicates that there are no locks available.</td> </tr> <tr> <td><code>ENOLINK</code></td> <td>Indications that a link has been severed.</td> </tr> <tr> <td><code>ENOMEM</code></td> <td>Indicates that there is not enough space.</td> </tr> <tr> <td><code>ENOMSG</code></td> <td>Indicates that there is no message of the desired type.</td> </tr> <tr> <td><code>ENOPROTOOPT</code></td> <td>Indicates that a given protocol is not available.</td> </tr> <tr> <td><code>ENOSPC</code></td> <td>Indicates that there is no space available on the device.</td> </tr> <tr> <td><code>ENOSR</code></td> <td>Indicates that there are no stream resources available.</td> </tr> <tr> <td><code>ENOSTR</code></td> <td>Indicates that a given resource is not a stream.</td> </tr> <tr> <td><code>ENOSYS</code></td> <td>Indicates that a function has not been implemented.</td> </tr> <tr> <td><code>ENOTCONN</code></td> <td>Indicates that the socket is not connected.</td> </tr> <tr> <td><code>ENOTDIR</code></td> <td>Indicates that the path is not a directory.</td> </tr> <tr> <td><code>ENOTEMPTY</code></td> <td>Indicates that the directory is not empty.</td> </tr> <tr> <td><code>ENOTSOCK</code></td> <td>Indicates that the given item is not a socket.</td> </tr> <tr> <td><code>ENOTSUP</code></td> <td>Indicates that a given operation is not supported.</td> </tr> <tr> <td><code>ENOTTY</code></td> <td>Indicates an inappropriate I/O control operation.</td> </tr> <tr> <td><code>ENXIO</code></td> <td>Indicates no such device or address.</td> </tr> <tr> <td><code>EOPNOTSUPP</code></td> <td>Indicates that an operation is not supported on the socket. Although <code>ENOTSUP</code> and <code>EOPNOTSUPP</code> have the same value on Linux, according to POSIX.1 these error values should be distinct.)</td> </tr> <tr> <td><code>EOVERFLOW</code></td> <td>Indicates that a value is too large to be stored in a given data type.</td> </tr> <tr> <td><code>EPERM</code></td> <td>Indicates that the operation is not permitted.</td> </tr> <tr> <td><code>EPIPE</code></td> <td>Indicates a broken pipe.</td> </tr> <tr> <td><code>EPROTO</code></td> <td>Indicates a protocol error.</td> </tr> <tr> <td><code>EPROTONOSUPPORT</code></td> <td>Indicates that a protocol is not supported.</td> </tr> <tr> <td><code>EPROTOTYPE</code></td> <td>Indicates the wrong type of protocol for a socket.</td> </tr> <tr> <td><code>ERANGE</code></td> <td>Indicates that the results are too large.</td> </tr> <tr> <td><code>EROFS</code></td> <td>Indicates that the file system is read only.</td> </tr> <tr> <td><code>ESPIPE</code></td> <td>Indicates an invalid seek operation.</td> </tr> <tr> <td><code>ESRCH</code></td> <td>Indicates that there is no such process.</td> </tr> <tr> <td><code>ESTALE</code></td> <td>Indicates that the file handle is stale.</td> </tr> <tr> <td><code>ETIME</code></td> <td>Indicates an expired timer.</td> </tr> <tr> <td><code>ETIMEDOUT</code></td> <td>Indicates that the connection timed out.</td> </tr> <tr> <td><code>ETXTBSY</code></td> <td>Indicates that a text file is busy.</td> </tr> <tr> <td><code>EWOULDBLOCK</code></td> <td>Indicates that the operation would block.</td> </tr> <tr> <td><code>EXDEV</code></td> <td>Indicates an improper link.</td> </tr> </tbody></table> </div><div> <h5>Windows-specific error constants<span><a class="mark" href="#windows-specific-error-constants" id="windows-specific-error-constants">#</a></span><a aria-hidden="true" class="legacy" id="os_windows_specific_error_constants"></a></h5> <p>The following error codes are specific to the Windows operating system.</p> <table> <tbody><tr> <th>Constant</th> <th>Description</th> </tr> <tr> <td><code>WSAEINTR</code></td> <td>Indicates an interrupted function call.</td> </tr> <tr> <td><code>WSAEBADF</code></td> <td>Indicates an invalid file handle.</td> </tr> <tr> <td><code>WSAEACCES</code></td> <td>Indicates insufficient permissions to complete the operation.</td> </tr> <tr> <td><code>WSAEFAULT</code></td> <td>Indicates an invalid pointer address.</td> </tr> <tr> <td><code>WSAEINVAL</code></td> <td>Indicates that an invalid argument was passed.</td> </tr> <tr> <td><code>WSAEMFILE</code></td> <td>Indicates that there are too many open files.</td> </tr> <tr> <td><code>WSAEWOULDBLOCK</code></td> <td>Indicates that a resource is temporarily unavailable.</td> </tr> <tr> <td><code>WSAEINPROGRESS</code></td> <td>Indicates that an operation is currently in progress.</td> </tr> <tr> <td><code>WSAEALREADY</code></td> <td>Indicates that an operation is already in progress.</td> </tr> <tr> <td><code>WSAENOTSOCK</code></td> <td>Indicates that the resource is not a socket.</td> </tr> <tr> <td><code>WSAEDESTADDRREQ</code></td> <td>Indicates that a destination address is required.</td> </tr> <tr> <td><code>WSAEMSGSIZE</code></td> <td>Indicates that the message size is too long.</td> </tr> <tr> <td><code>WSAEPROTOTYPE</code></td> <td>Indicates the wrong protocol type for the socket.</td> </tr> <tr> <td><code>WSAENOPROTOOPT</code></td> <td>Indicates a bad protocol option.</td> </tr> <tr> <td><code>WSAEPROTONOSUPPORT</code></td> <td>Indicates that the protocol is not supported.</td> </tr> <tr> <td><code>WSAESOCKTNOSUPPORT</code></td> <td>Indicates that the socket type is not supported.</td> </tr> <tr> <td><code>WSAEOPNOTSUPP</code></td> <td>Indicates that the operation is not supported.</td> </tr> <tr> <td><code>WSAEPFNOSUPPORT</code></td> <td>Indicates that the protocol family is not supported.</td> </tr> <tr> <td><code>WSAEAFNOSUPPORT</code></td> <td>Indicates that the address family is not supported.</td> </tr> <tr> <td><code>WSAEADDRINUSE</code></td> <td>Indicates that the network address is already in use.</td> </tr> <tr> <td><code>WSAEADDRNOTAVAIL</code></td> <td>Indicates that the network address is not available.</td> </tr> <tr> <td><code>WSAENETDOWN</code></td> <td>Indicates that the network is down.</td> </tr> <tr> <td><code>WSAENETUNREACH</code></td> <td>Indicates that the network is unreachable.</td> </tr> <tr> <td><code>WSAENETRESET</code></td> <td>Indicates that the network connection has been reset.</td> </tr> <tr> <td><code>WSAECONNABORTED</code></td> <td>Indicates that the connection has been aborted.</td> </tr> <tr> <td><code>WSAECONNRESET</code></td> <td>Indicates that the connection has been reset by the peer.</td> </tr> <tr> <td><code>WSAENOBUFS</code></td> <td>Indicates that there is no buffer space available.</td> </tr> <tr> <td><code>WSAEISCONN</code></td> <td>Indicates that the socket is already connected.</td> </tr> <tr> <td><code>WSAENOTCONN</code></td> <td>Indicates that the socket is not connected.</td> </tr> <tr> <td><code>WSAESHUTDOWN</code></td> <td>Indicates that data cannot be sent after the socket has been shutdown.</td> </tr> <tr> <td><code>WSAETOOMANYREFS</code></td> <td>Indicates that there are too many references.</td> </tr> <tr> <td><code>WSAETIMEDOUT</code></td> <td>Indicates that the connection has timed out.</td> </tr> <tr> <td><code>WSAECONNREFUSED</code></td> <td>Indicates that the connection has been refused.</td> </tr> <tr> <td><code>WSAELOOP</code></td> <td>Indicates that a name cannot be translated.</td> </tr> <tr> <td><code>WSAENAMETOOLONG</code></td> <td>Indicates that a name was too long.</td> </tr> <tr> <td><code>WSAEHOSTDOWN</code></td> <td>Indicates that a network host is down.</td> </tr> <tr> <td><code>WSAEHOSTUNREACH</code></td> <td>Indicates that there is no route to a network host.</td> </tr> <tr> <td><code>WSAENOTEMPTY</code></td> <td>Indicates that the directory is not empty.</td> </tr> <tr> <td><code>WSAEPROCLIM</code></td> <td>Indicates that there are too many processes.</td> </tr> <tr> <td><code>WSAEUSERS</code></td> <td>Indicates that the user quota has been exceeded.</td> </tr> <tr> <td><code>WSAEDQUOT</code></td> <td>Indicates that the disk quota has been exceeded.</td> </tr> <tr> <td><code>WSAESTALE</code></td> <td>Indicates a stale file handle reference.</td> </tr> <tr> <td><code>WSAEREMOTE</code></td> <td>Indicates that the item is remote.</td> </tr> <tr> <td><code>WSASYSNOTREADY</code></td> <td>Indicates that the network subsystem is not ready.</td> </tr> <tr> <td><code>WSAVERNOTSUPPORTED</code></td> <td>Indicates that the <code>winsock.dll</code> version is out of range.</td> </tr> <tr> <td><code>WSANOTINITIALISED</code></td> <td>Indicates that successful WSAStartup has not yet been performed.</td> </tr> <tr> <td><code>WSAEDISCON</code></td> <td>Indicates that a graceful shutdown is in progress.</td> </tr> <tr> <td><code>WSAENOMORE</code></td> <td>Indicates that there are no more results.</td> </tr> <tr> <td><code>WSAECANCELLED</code></td> <td>Indicates that an operation has been canceled.</td> </tr> <tr> <td><code>WSAEINVALIDPROCTABLE</code></td> <td>Indicates that the procedure call table is invalid.</td> </tr> <tr> <td><code>WSAEINVALIDPROVIDER</code></td> <td>Indicates an invalid service provider.</td> </tr> <tr> <td><code>WSAEPROVIDERFAILEDINIT</code></td> <td>Indicates that the service provider failed to initialized.</td> </tr> <tr> <td><code>WSASYSCALLFAILURE</code></td> <td>Indicates a system call failure.</td> </tr> <tr> <td><code>WSASERVICE_NOT_FOUND</code></td> <td>Indicates that a service was not found.</td> </tr> <tr> <td><code>WSATYPE_NOT_FOUND</code></td> <td>Indicates that a class type was not found.</td> </tr> <tr> <td><code>WSA_E_NO_MORE</code></td> <td>Indicates that there are no more results.</td> </tr> <tr> <td><code>WSA_E_CANCELLED</code></td> <td>Indicates that the call was canceled.</td> </tr> <tr> <td><code>WSAEREFUSED</code></td> <td>Indicates that a database query was refused.</td> </tr> </tbody></table> </div></div><div> <h4>dlopen constants<span><a class="mark" href="#dlopen-constants" id="dlopen-constants">#</a></span><a aria-hidden="true" class="legacy" id="os_dlopen_constants"></a></h4> <p>If available on the operating system, the following constants are exported in <code>os.constants.dlopen</code>. See <a href="http://man7.org/linux/man-pages/man3/dlopen.3.html"><code>dlopen(3)</code></a> for detailed information.</p> <table> <tbody><tr> <th>Constant</th> <th>Description</th> </tr> <tr> <td><code>RTLD_LAZY</code></td> <td>Perform lazy binding. Node.js sets this flag by default.</td> </tr> <tr> <td><code>RTLD_NOW</code></td> <td>Resolve all undefined symbols in the library before dlopen(3) returns.</td> </tr> <tr> <td><code>RTLD_GLOBAL</code></td> <td>Symbols defined by the library will be made available for symbol resolution of subsequently loaded libraries.</td> </tr> <tr> <td><code>RTLD_LOCAL</code></td> <td>The converse of <code>RTLD_GLOBAL</code>. This is the default behavior if neither flag is specified.</td> </tr> <tr> <td><code>RTLD_DEEPBIND</code></td> <td>Make a self-contained library use its own symbols in preference to symbols from previously loaded libraries.</td> </tr> </tbody></table> </div><div> <h4>Priority constants<span><a class="mark" href="#priority-constants" id="priority-constants">#</a></span><a aria-hidden="true" class="legacy" id="os_priority_constants"></a></h4> <div class="api_metadata"> <span>Added in: v10.10.0</span> </div> <p>The following process scheduling constants are exported by <code>os.constants.priority</code>.</p> <table> <tbody><tr> <th>Constant</th> <th>Description</th> </tr> <tr> <td><code>PRIORITY_LOW</code></td> <td>The lowest process scheduling priority. This corresponds to <code>IDLE_PRIORITY_CLASS</code> on Windows, and a nice value of <code>19</code> on all other platforms.</td> </tr> <tr> <td><code>PRIORITY_BELOW_NORMAL</code></td> <td>The process scheduling priority above <code>PRIORITY_LOW</code> and below <code>PRIORITY_NORMAL</code>. This corresponds to <code>BELOW_NORMAL_PRIORITY_CLASS</code> on Windows, and a nice value of <code>10</code> on all other platforms.</td> </tr> <tr> <td><code>PRIORITY_NORMAL</code></td> <td>The default process scheduling priority. This corresponds to <code>NORMAL_PRIORITY_CLASS</code> on Windows, and a nice value of <code>0</code> on all other platforms.</td> </tr> <tr> <td><code>PRIORITY_ABOVE_NORMAL</code></td> <td>The process scheduling priority above <code>PRIORITY_NORMAL</code> and below <code>PRIORITY_HIGH</code>. This corresponds to <code>ABOVE_NORMAL_PRIORITY_CLASS</code> on Windows, and a nice value of <code>-7</code> on all other platforms.</td> </tr> <tr> <td><code>PRIORITY_HIGH</code></td> <td>The process scheduling priority above <code>PRIORITY_ABOVE_NORMAL</code> and below <code>PRIORITY_HIGHEST</code>. This corresponds to <code>HIGH_PRIORITY_CLASS</code> on Windows, and a nice value of <code>-14</code> on all other platforms.</td> </tr> <tr> <td><code>PRIORITY_HIGHEST</code></td> <td>The highest process scheduling priority. This corresponds to <code>REALTIME_PRIORITY_CLASS</code> on Windows, and a nice value of <code>-20</code> on all other platforms.</td> </tr> </tbody></table> </div><div> <h4>libuv constants<span><a class="mark" href="#libuv-constants" id="libuv-constants">#</a></span><a aria-hidden="true" class="legacy" id="os_libuv_constants"></a></h4> <table> <tbody><tr> <th>Constant</th> <th>Description</th> </tr> <tr> <td><code>UV_UDP_REUSEADDR</code></td> <td></td> </tr> </tbody></table></div></section> <!-- API END --> </div> </div> </div> </body> </html>