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<!DOCTYPE html><html lang="en"><head><meta charset="utf-8"><meta name="viewport" content="width=device-width, initial-scale=1.0"><meta name="generator" content="rustdoc"><meta name="description" content="API documentation for the Rust `initgroups` fn in crate `nix`."><meta name="keywords" content="rust, rustlang, rust-lang, initgroups"><title>nix::unistd::initgroups - Rust</title><link rel="stylesheet" type="text/css" href="../../normalize.css"><link rel="stylesheet" type="text/css" href="../../rustdoc.css" id="mainThemeStyle"><link rel="stylesheet" type="text/css" href="../../dark.css"><link rel="stylesheet" type="text/css" href="../../light.css" id="themeStyle"><script src="../../storage.js"></script><noscript><link rel="stylesheet" href="../../noscript.css"></noscript><link rel="shortcut icon" href="../../favicon.ico"><style type="text/css">#crate-search{background-image:url("../../down-arrow.svg");}</style></head><body class="rustdoc fn"><!--[if lte IE 8]><div class="warning">This old browser is unsupported and will most likely display funky things.</div><![endif]--><nav class="sidebar"><div class="sidebar-menu">&#9776;</div><a href='../../nix/index.html'><div class='logo-container'><img src='../../rust-logo.png' alt='logo'></div></a><div class="sidebar-elems"><p class='location'><a href='../index.html'>nix</a>::<wbr><a href='index.html'>unistd</a></p><script>window.sidebarCurrent = {name: 'initgroups', ty: 'fn', relpath: ''};</script><script defer src="sidebar-items.js"></script></div></nav><div class="theme-picker"><button id="theme-picker" aria-label="Pick another theme!"><img src="../../brush.svg" width="18" alt="Pick another theme!"></button><div id="theme-choices"></div></div><script src="../../theme.js"></script><nav class="sub"><form class="search-form js-only"><div class="search-container"><div><select id="crate-search"><option value="All crates">All crates</option></select><input class="search-input" name="search" autocomplete="off" spellcheck="false" placeholder="Click or press S to search, ? for more options…" type="search"></div><a id="settings-menu" href="../../settings.html"><img src="../../wheel.svg" width="18" alt="Change settings"></a></div></form></nav><section id="main" class="content"><h1 class='fqn'><span class='out-of-band'><span id='render-detail'><a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class='inner'>&#x2212;</span>]</a></span><a class='srclink' href='../../src/nix/unistd.rs.html#1523-1535' title='goto source code'>[src]</a></span><span class='in-band'>Function <a href='../index.html'>nix</a>::<wbr><a href='index.html'>unistd</a>::<wbr><a class="fn" href=''>initgroups</a></span></h1><pre class='rust fn'>pub fn initgroups(user: &amp;<a class="struct" href="https://doc.rust-lang.org/nightly/std/ffi/c_str/struct.CStr.html" title="struct std::ffi::c_str::CStr">CStr</a>, group: <a class="struct" href="../../nix/unistd/struct.Gid.html" title="struct nix::unistd::Gid">Gid</a>) -&gt; <a class="type" href="../../nix/type.Result.html" title="type nix::Result">Result</a>&lt;<a class="primitive" href="https://doc.rust-lang.org/nightly/std/primitive.unit.html">()</a>&gt;</pre><div class='docblock'><p>Initialize the supplementary group access list.</p>
<p>Sets the supplementary group IDs for the calling process using all groups
that <code>user</code> is a member of. The additional group <code>group</code> is also added to
the list.</p>
<p><a href="http://man7.org/linux/man-pages/man3/initgroups.3.html">Further reading</a></p>
<p><strong>Note:</strong> This function is not available for Apple platforms. On those
platforms, group membership management should be achieved via communication
with the <code>opendirectoryd</code> service.</p>
<h1 id="examples" class="section-header"><a href="#examples">Examples</a></h1>
<p><code>initgroups</code> can be used when dropping privileges from the root user to
another user. For example, given the user <code>www-data</code>, we could look up the
UID and GID for the user in the system's password database (usually found
in <code>/etc/passwd</code>). If the <code>www-data</code> user's UID and GID were <code>33</code> and <code>33</code>,
respectively, one could switch the user as follows:</p>
<div class="example-wrap"><pre class="rust rust-example-rendered">
<span class="kw">let</span> <span class="ident">user</span> <span class="op">=</span> <span class="ident">CString</span>::<span class="ident">new</span>(<span class="string">&quot;www-data&quot;</span>).<span class="ident">unwrap</span>();
<span class="kw">let</span> <span class="ident">uid</span> <span class="op">=</span> <span class="ident">Uid</span>::<span class="ident">from_raw</span>(<span class="number">33</span>);
<span class="kw">let</span> <span class="ident">gid</span> <span class="op">=</span> <span class="ident">Gid</span>::<span class="ident">from_raw</span>(<span class="number">33</span>);
<span class="ident">initgroups</span>(<span class="kw-2">&amp;</span><span class="ident">user</span>, <span class="ident">gid</span>)<span class="question-mark">?</span>;
<span class="ident">setgid</span>(<span class="ident">gid</span>)<span class="question-mark">?</span>;
<span class="ident">setuid</span>(<span class="ident">uid</span>)<span class="question-mark">?</span>;</pre></div>
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