<!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 `remove_var` fn in crate `std`."><meta name="keywords" content="rust, rustlang, rust-lang, remove_var"><title>std::env::remove_var - 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><link rel="shortcut icon" href="https://doc.rust-lang.org/favicon.ico"></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">☰</div><a href='../../std/index.html'><img src='https://www.rust-lang.org/logos/rust-logo-128x128-blk-v2.png' alt='logo' width='100'></a><div class="sidebar-elems"><p class='location'><a href='../index.html'>std</a>::<wbr><a href='index.html'>env</a></p><script>window.sidebarCurrent = {name: 'remove_var', 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"><input class="search-input" name="search" autocomplete="off" placeholder="Click or press ‘S’ to search, ‘?’ for more options…" type="search"><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='in-band'>Function <a href='../index.html'>std</a>::<wbr><a href='index.html'>env</a>::<wbr><a class="fn" href=''>remove_var</a></span><span class='out-of-band'><span class='since' title='Stable since Rust version 1.0.0'>1.0.0</span><span id='render-detail'><a id="toggle-all-docs" href="javascript:void(0)" title="collapse all docs">[<span class='inner'>−</span>]</a></span><a class='srclink' href='../../src/std/env.rs.html#359-361' title='goto source code'>[src]</a></span></h1><pre class='rust fn'>pub fn remove_var<K: <a class="trait" href="../../std/convert/trait.AsRef.html" title="trait std::convert::AsRef">AsRef</a><<a class="struct" href="../../std/ffi/struct.OsStr.html" title="struct std::ffi::OsStr">OsStr</a>>>(k: K)</pre><div class='docblock'><p>Removes an environment variable from the environment of the currently running process.</p>
<p>Note that while concurrent access to environment variables is safe in Rust,
some platforms only expose inherently unsafe non-threadsafe APIs for
inspecting the environment. As a result extra care needs to be taken when
auditing calls to unsafe external FFI functions to ensure that any external
environment accesses are properly synchronized with accesses in Rust.</p>
<p>Discussion of this unsafety on Unix may be found in:</p>
<ul>
<li><a href="http://austingroupbugs.net/view.php?id=188">Austin Group Bugzilla</a></li>
<li><a href="https://sourceware.org/bugzilla/show_bug.cgi?id=15607#c2">GNU C library Bugzilla</a></li>
</ul>
<h1 id="panics" class="section-header"><a href="#panics">Panics</a></h1>
<p>This function may panic if <code>key</code> is empty, contains an ASCII equals sign
<code>'='</code> or the NUL character <code>'\0'</code>, or when the value contains the NUL
character.</p>
<h1 id="examples" class="section-header"><a href="#examples">Examples</a></h1>
<pre class="rust rust-example-rendered">
<span class="kw">use</span> <span class="ident">std</span>::<span class="ident">env</span>;
<span class="kw">let</span> <span class="ident">key</span> <span class="op">=</span> <span class="string">"KEY"</span>;
<span class="ident">env</span>::<span class="ident">set_var</span>(<span class="ident">key</span>, <span class="string">"VALUE"</span>);
<span class="macro">assert_eq</span><span class="macro">!</span>(<span class="ident">env</span>::<span class="ident">var</span>(<span class="ident">key</span>), <span class="prelude-val">Ok</span>(<span class="string">"VALUE"</span>.<span class="ident">to_string</span>()));
<span class="ident">env</span>::<span class="ident">remove_var</span>(<span class="ident">key</span>);
<span class="macro">assert</span><span class="macro">!</span>(<span class="ident">env</span>::<span class="ident">var</span>(<span class="ident">key</span>).<span class="ident">is_err</span>());<a class="test-arrow" target="_blank" href="https://play.rust-lang.org/?code=%23!%5Ballow(unused)%5D%0Afn%20main()%20%7B%0Ause%20std%3A%3Aenv%3B%0A%0Alet%20key%20%3D%20%22KEY%22%3B%0Aenv%3A%3Aset_var(key%2C%20%22VALUE%22)%3B%0Aassert_eq!(env%3A%3Avar(key)%2C%20Ok(%22VALUE%22.to_string()))%3B%0A%0Aenv%3A%3Aremove_var(key)%3B%0Aassert!(env%3A%3Avar(key).is_err())%3B%0A%7D">Run</a></pre>
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