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<h2>Table of Contents</h2>
<ul>
<li>
<p><span class="stability_2"><a href="#os_os">OS</a></span></p>
<ul>
<li><a href="#os_os_eol">os.EOL</a></li>
<li><a href="#os_os_arch">os.arch()</a></li>
<li><a href="#os_os_constants">os.constants</a></li>
<li><a href="#os_os_cpus">os.cpus()</a></li>
<li><a href="#os_os_endianness">os.endianness()</a></li>
<li><a href="#os_os_freemem">os.freemem()</a></li>
<li><a href="#os_os_getpriority_pid">os.getPriority([pid])</a></li>
<li><a href="#os_os_homedir">os.homedir()</a></li>
<li><a href="#os_os_hostname">os.hostname()</a></li>
<li><a href="#os_os_loadavg">os.loadavg()</a></li>
<li><a href="#os_os_networkinterfaces">os.networkInterfaces()</a></li>
<li><a href="#os_os_platform">os.platform()</a></li>
<li><a href="#os_os_release">os.release()</a></li>
<li><a href="#os_os_setpriority_pid_priority">os.setPriority([pid, ]priority)</a></li>
<li><a href="#os_os_tmpdir">os.tmpdir()</a></li>
<li><a href="#os_os_totalmem">os.totalmem()</a></li>
<li><a href="#os_os_type">os.type()</a></li>
<li><a href="#os_os_uptime">os.uptime()</a></li>
<li><a href="#os_os_userinfo_options">os.userInfo([options])</a></li>
<li>
<p><a href="#os_os_constants_1">OS Constants</a></p>
<ul>
<li><a href="#os_signal_constants">Signal Constants</a></li>
<li>
<p><a href="#os_error_constants">Error Constants</a></p>
<ul>
<li><a href="#os_posix_error_constants">POSIX Error Constants</a></li>
<li><a href="#os_windows_specific_error_constants">Windows Specific Error Constants</a></li>
</ul>
</li>
<li><a href="#os_dlopen_constants">dlopen Constants</a></li>
<li><a href="#os_priority_constants">Priority Constants</a></li>
<li><a href="#os_libuv_constants">libuv Constants</a></li>
</ul>
</li>
</ul>
</li>
</ul>
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<div id="apicontent">
<h1>OS<span><a class="mark" href="#os_os" id="os_os">#</a></span></h1>
<p></p><div class="api_stability api_stability_2"><a href="documentation.html#documentation_stability_index">Stability: 2</a> - Stable</div><p></p>
<p>The <code>os</code> module provides a number of operating system-related utility methods.
It can be accessed using:</p>
<pre><code class="language-js">const os = require('os');
</code></pre>
<h2>os.EOL<span><a class="mark" href="#os_os_eol" id="os_os_eol">#</a></span></h2>
<div class="api_metadata">
<span>Added in: v0.7.8</span>
</div>
<ul>
<li><a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Data_structures#String_type" class="type"><string></a></li>
</ul>
<p>A string constant defining 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>
<h2>os.arch()<a class="srclink" href="https://github.com/nodejs/node/blob/5182a7ece0b71feeb9157f7aa348a15d53e32058/lib/os.js#L112">[src]</a><span><a class="mark" href="#os_os_arch" id="os_os_arch">#</a></span></h2>
<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>The <code>os.arch()</code> method returns a string identifying the operating system CPU
architecture for which the Node.js binary was compiled.</p>
<p>The current possible values are: <code>'arm'</code>, <code>'arm64'</code>, <code>'ia32'</code>, <code>'mips'</code>,
<code>'mipsel'</code>, <code>'ppc'</code>, <code>'ppc64'</code>, <code>'s390'</code>, <code>'s390x'</code>, <code>'x32'</code>, and <code>'x64'</code>.</p>
<p>Equivalent to <a href="process.html#process_process_arch"><code>process.arch</code></a>.</p>
<h2>os.constants<span><a class="mark" href="#os_os_constants" id="os_os_constants">#</a></span></h2>
<div class="api_metadata">
<span>Added in: v6.3.0</span>
</div>
<ul>
<li><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 commonly used operating system specific constants
for error codes, process signals, and so on. The specific constants currently
defined are described in <a href="#os_os_constants_1">OS Constants</a>.</p>
<h2>os.cpus()<a class="srclink" href="https://github.com/nodejs/node/blob/5182a7ece0b71feeb9157f7aa348a15d53e32058/lib/os.js#L108">[src]</a><span><a class="mark" href="#os_os_cpus" id="os_os_cpus">#</a></span></h2>
<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>The <code>os.cpus()</code> method returns an array of objects containing information about
each logical CPU core.</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>
<p><code>times</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a></p>
<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 semi -->
<pre><code class="language-js">[
{
model: 'Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz',
speed: 2926,
times: {
user: 252020,
nice: 0,
sys: 30340,
idle: 1070356870,
irq: 0
}
},
{
model: 'Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz',
speed: 2926,
times: {
user: 306960,
nice: 0,
sys: 26980,
idle: 1071569080,
irq: 0
}
},
{
model: 'Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz',
speed: 2926,
times: {
user: 248450,
nice: 0,
sys: 21750,
idle: 1070919370,
irq: 0
}
},
{
model: 'Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz',
speed: 2926,
times: {
user: 256880,
nice: 0,
sys: 19430,
idle: 1070905480,
irq: 20
}
},
{
model: 'Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz',
speed: 2926,
times: {
user: 511580,
nice: 20,
sys: 40900,
idle: 1070842510,
irq: 0
}
},
{
model: 'Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz',
speed: 2926,
times: {
user: 291660,
nice: 0,
sys: 34360,
idle: 1070888000,
irq: 10
}
},
{
model: 'Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz',
speed: 2926,
times: {
user: 308260,
nice: 0,
sys: 55410,
idle: 1071129970,
irq: 880
}
},
{
model: 'Intel(R) Core(TM) i7 CPU 860 @ 2.80GHz',
speed: 2926,
times: {
user: 266450,
nice: 1480,
sys: 34920,
idle: 1072572010,
irq: 30
}
}
]
</code></pre>
<p>Because <code>nice</code> values are UNIX-specific, on Windows the <code>nice</code> values of all
processors are always 0.</p>
<h2>os.endianness()<a class="srclink" href="https://github.com/nodejs/node/blob/5182a7ece0b71feeb9157f7aa348a15d53e32058/lib/os.js#L143">[src]</a><span><a class="mark" href="#os_os_endianness" id="os_os_endianness">#</a></span></h2>
<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>The <code>os.endianness()</code> method returns a string identifying the endianness of the
CPU <em>for which the Node.js binary was compiled</em>.</p>
<p>Possible values are:</p>
<ul>
<li><code>'BE'</code> for big endian</li>
<li><code>'LE'</code> for little endian.</li>
</ul>
<h2>os.freemem()<span><a class="mark" href="#os_os_freemem" id="os_os_freemem">#</a></span></h2>
<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>The <code>os.freemem()</code> method returns the amount of free system memory in bytes as
an integer.</p>
<h2>os.getPriority([pid])<a class="srclink" href="https://github.com/nodejs/node/blob/5182a7ece0b71feeb9157f7aa348a15d53e32058/lib/os.js#L226">[src]</a><span><a class="mark" href="#os_os_getpriority_pid" id="os_os_getpriority_pid">#</a></span></h2>
<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>The <code>os.getPriority()</code> method 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>
<h2>os.homedir()<span><a class="mark" href="#os_os_homedir" id="os_os_homedir">#</a></span></h2>
<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>The <code>os.homedir()</code> method returns the home directory of the current user as a
string.</p>
<h2>os.hostname()<span><a class="mark" href="#os_os_hostname" id="os_os_hostname">#</a></span></h2>
<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>The <code>os.hostname()</code> method returns the hostname of the operating system as a
string.</p>
<h2>os.loadavg()<a class="srclink" href="https://github.com/nodejs/node/blob/5182a7ece0b71feeb9157f7aa348a15d53e32058/lib/os.js#L87">[src]</a><span><a class="mark" href="#os_os_loadavg" id="os_os_loadavg">#</a></span></h2>
<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>The <code>os.loadavg()</code> method 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. As a rule of thumb, the load
average should ideally be less than the number of logical CPUs in the system.</p>
<p>The load average is a UNIX-specific concept with no real equivalent on
Windows platforms. On Windows, the return value is always <code>[0, 0, 0]</code>.</p>
<h2>os.networkInterfaces()<a class="srclink" href="https://github.com/nodejs/node/blob/5182a7ece0b71feeb9157f7aa348a15d53e32058/lib/os.js#L197">[src]</a><span><a class="mark" href="#os_os_networkinterfaces" id="os_os_networkinterfaces">#</a></span></h2>
<div class="api_metadata">
<span>Added in: v0.6.0</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>The <code>os.networkInterfaces()</code> method returns an object containing only 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">{
lo: [
{
address: '127.0.0.1',
netmask: '255.0.0.0',
family: 'IPv4',
mac: '00:00:00:00:00:00',
internal: true,
cidr: '127.0.0.1/8'
},
{
address: '::1',
netmask: 'ffff:ffff:ffff:ffff:ffff:ffff:ffff:ffff',
family: 'IPv6',
mac: '00:00:00:00:00:00',
scopeid: 0,
internal: true,
cidr: '::1/128'
}
],
eth0: [
{
address: '192.168.1.108',
netmask: '255.255.255.0',
family: 'IPv4',
mac: '01:02:03:0a:0b:0c',
internal: false,
cidr: '192.168.1.108/24'
},
{
address: 'fe80::a00:27ff:fe4e:66a1',
netmask: 'ffff:ffff:ffff:ffff::',
family: 'IPv6',
mac: '01:02:03:0a:0b:0c',
scopeid: 1,
internal: false,
cidr: 'fe80::a00:27ff:fe4e:66a1/64'
}
]
}
</code></pre>
<h2>os.platform()<a class="srclink" href="https://github.com/nodejs/node/blob/5182a7ece0b71feeb9157f7aa348a15d53e32058/lib/os.js#L117">[src]</a><span><a class="mark" href="#os_os_platform" id="os_os_platform">#</a></span></h2>
<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>The <code>os.platform()</code> method returns a string identifying the operating system
platform as set during compile time of Node.js.</p>
<p>Currently possible values are:</p>
<ul>
<li><code>'aix'</code></li>
<li><code>'darwin'</code></li>
<li><code>'freebsd'</code></li>
<li><code>'linux'</code></li>
<li><code>'openbsd'</code></li>
<li><code>'sunos'</code></li>
<li><code>'win32'</code></li>
</ul>
<p>Equivalent to <a href="process.html#process_process_platform"><code>process.platform</code></a>.</p>
<p>The value <code>'android'</code> may also be returned if the Node.js is built on the
Android operating system. However, Android support in Node.js is considered
<a href="https://github.com/nodejs/node/blob/master/BUILDING.md#androidandroid-based-devices-eg-firefox-os">to be experimental</a> at this time.</p>
<h2>os.release()<span><a class="mark" href="#os_os_release" id="os_os_release">#</a></span></h2>
<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>The <code>os.release()</code> method returns a string identifying the operating system
release.</p>
<p>On POSIX systems, the operating system release is determined by calling
<a href="https://linux.die.net/man/3/uname"></a><a href="http://man7.org/linux/man-pages/man3/uname.3.html"><code>uname(3)</code></a>. On Windows, <code>GetVersionExW()</code> is used. Please see
<a href="https://en.wikipedia.org/wiki/Uname#Examples">https://en.wikipedia.org/wiki/Uname#Examples</a> for more information.</p>
<h2>os.setPriority([pid, ]priority)<a class="srclink" href="https://github.com/nodejs/node/blob/5182a7ece0b71feeb9157f7aa348a15d53e32058/lib/os.js#L211">[src]</a><span><a class="mark" href="#os_os_setpriority_pid_priority" id="os_os_setpriority_pid_priority">#</a></span></h2>
<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>The <code>os.setPriority()</code> method 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 priority
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, it is recommended to set <code>priority</code> to one of the priority constants.</p>
<p>On Windows setting priority to <code>PRIORITY_HIGHEST</code> requires elevated user,
otherwise the set priority will be silently reduced to <code>PRIORITY_HIGH</code>.</p>
<h2>os.tmpdir()<a class="srclink" href="https://github.com/nodejs/node/blob/5182a7ece0b71feeb9157f7aa348a15d53e32058/lib/os.js#L122">[src]</a><span><a class="mark" href="#os_os_tmpdir" id="os_os_tmpdir">#</a></span></h2>
<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>The <code>os.tmpdir()</code> method returns a string specifying the operating system's
default directory for temporary files.</p>
<h2>os.totalmem()<span><a class="mark" href="#os_os_totalmem" id="os_os_totalmem">#</a></span></h2>
<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>The <code>os.totalmem()</code> method returns the total amount of system memory in bytes
as an integer.</p>
<h2>os.type()<span><a class="mark" href="#os_os_type" id="os_os_type">#</a></span></h2>
<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>The <code>os.type()</code> method returns a string identifying the operating system name
as returned by <a href="https://linux.die.net/man/3/uname"></a><a href="http://man7.org/linux/man-pages/man3/uname.3.html"><code>uname(3)</code></a>. For example, <code>'Linux'</code> on Linux, <code>'Darwin'</code> on
macOS, and <code>'Windows_NT'</code> on Windows.</p>
<p>Please 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"></a><a href="http://man7.org/linux/man-pages/man3/uname.3.html"><code>uname(3)</code></a> on various operating
systems.</p>
<h2>os.uptime()<span><a class="mark" href="#os_os_uptime" id="os_os_uptime">#</a></span></h2>
<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>The <code>os.uptime()</code> method returns the system uptime in number of seconds.</p>
<h2>os.userInfo([options])<a class="srclink" href="https://github.com/nodejs/node/blob/5182a7ece0b71feeb9157f7aa348a15d53e32058/lib/os.js#L241">[src]</a><span><a class="mark" href="#os_os_userinfo_options" id="os_os_userinfo_options">#</a></span></h2>
<div class="api_metadata">
<span>Added in: v6.0.0</span>
</div>
<ul>
<li>
<p><code>options</code> <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Object" class="type"><Object></a></p>
<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>The <code>os.userInfo()</code> method 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 several
environment variables for the home directory before falling back to the
operating system response.</p>
<h2>OS Constants<span><a class="mark" href="#os_os_constants_1" id="os_os_constants_1">#</a></span></h2>
<p>The following constants are exported by <code>os.constants</code>.</p>
<p>Not all constants will be available on every operating system.</p>
<h3>Signal Constants<span><a class="mark" href="#os_signal_constants" id="os_signal_constants">#</a></span></h3>
<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
(<code>(Ctrl+C)</code>).</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>
<h3>Error Constants<span><a class="mark" href="#os_error_constants" id="os_error_constants">#</a></span></h3>
<p>The following error constants are exported by <code>os.constants.errno</code>:</p>
<h4>POSIX Error Constants<span><a class="mark" href="#os_posix_error_constants" id="os_posix_error_constants">#</a></span></h4>
<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 currently 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. Note that
while <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>
<h4>Windows Specific Error Constants<span><a class="mark" href="#os_windows_specific_error_constants" id="os_windows_specific_error_constants">#</a></span></h4>
<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>
<h3>dlopen Constants<span><a class="mark" href="#os_dlopen_constants" id="os_dlopen_constants">#</a></span></h3>
<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>
<h3>Priority Constants<span><a class="mark" href="#os_priority_constants" id="os_priority_constants">#</a></span></h3>
<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>
<h3>libuv Constants<span><a class="mark" href="#os_libuv_constants" id="os_libuv_constants">#</a></span></h3>
<table>
<tbody><tr>
<th>Constant</th>
<th>Description</th>
</tr>
<tr>
<td><code>UV_UDP_REUSEADDR</code></td>
<td></td>
</tr>
</tbody></table>
</div>
</div>
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