167 lines
21 KiB
HTML
167 lines
21 KiB
HTML
<!DOCTYPE html>
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<html lang="zh" dir="ltr" class="client-nojs" xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh">
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<head><meta http-equiv="x-ua-compatible" content="ie=edge">
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<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
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<title>std::filesystem::permissions</title>
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<link rel="stylesheet" href="ext.css" />
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<link rel="stylesheet" href="site_modules.css" />
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</head>
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_filesystem_permissions skin-cppreference2 action-view cpp-navbar">
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<div id="cpp-content-base">
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<div id="content"><a id="top"></a>
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::filesystem::</span>permissions</h1>
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<div id="bodyContent">
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<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-filesystem.html">filesystem</a></span></div>
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<div id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr" xml:lang="zh">
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<table class="t-dcl-begin">
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<tbody>
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<tr class="t-dsc-header">
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<td>
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<div>定义于头文件 <code><a href="cpp-header-filesystem.html"><filesystem></a></code></div>
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</td>
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<td></td>
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<td></td>
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</tr>
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<tr class="t-dcl t-since-cxx17">
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<td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw4">void</span> permissions<span class="br0">(</span><span class="kw4">const</span> <a href="cpp-filesystem-path.html"><span class="kw2199">std::<span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">path</span></span></a><span class="sy3">&</span> p,<br /></span>
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<p> <a href="cpp-filesystem-perms.html"><span class="kw2219">std::<span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">perms</span></span></a> prms,<br />
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std<span class="sy4">::</span><span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">perm_options</span> opts <span class="sy1">=</span> perm_options<span class="sy4">::</span><span class="me2">replace</span><span class="br0">)</span><span class="sy4">;</span><br />
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<span class="kw4">void</span> permissions<span class="br0">(</span><span class="kw4">const</span> <a href="cpp-filesystem-path.html"><span class="kw2199">std::<span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">path</span></span></a><span class="sy3">&</span> p,<br />
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<a href="cpp-filesystem-perms.html"><span class="kw2219">std::<span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">perms</span></span></a> prms,<br />
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<a href="cpp-error-error_code.html"><span class="kw877">std::<span class="me2">error_code</span></span></a><span class="sy3">&</span> ec<span class="br0">)</span> <span class="kw1">noexcept</span><span class="sy4">;</span><br />
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<span class="kw4">void</span> permissions<span class="br0">(</span><span class="kw4">const</span> <a href="cpp-filesystem-path.html"><span class="kw2199">std::<span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">path</span></span></a><span class="sy3">&</span> p,<br />
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<a href="cpp-filesystem-perms.html"><span class="kw2219">std::<span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">perms</span></span></a> prms,<br />
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std<span class="sy4">::</span><span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">perm_options</span> opts,<br /></p>
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<a href="cpp-error-error_code.html"><span class="kw877">std::<span class="me2">error_code</span></span></a><span class="sy3">&</span> ec<span class="br0">)</span><span class="sy4">;</span></div>
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</td>
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<td class="t-dcl-nopad"></td>
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<td><span class="t-mark-rev t-since-cxx17">(C++17 起)</span></td>
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</tr>
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<tr class="t-dcl-sep">
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<td></td>
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<td></td>
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<td></td>
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</tr>
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</tbody>
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</table>
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<p>更改 <code>p</code> 所决定的文件的访问权限，如同用 POSIX <a rel="nofollow" class="external text" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/fchmodat.html">fchmodat</a> 。跟随符号链接，除非在 <code>opts</code> 中设置了 <code>perm_options::nofollow</code> 。</p>
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<p>第二个签名表现如同以设为 <span class="t-c"><span class="mw-geshi cpp source-cpp">perm_options<span class="sy4">::</span><span class="me2">replace</span></span></span> 的 <code>opts</code> 调用</p>
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<p>效果按如下方式依赖于 <code>prms</code> 与 <code>opts</code> ：</p>
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<ul>
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<li>若 <code>opts</code> 是 <span class="t-c"><span class="mw-geshi cpp source-cpp">perm_options<span class="sy4">::</span><span class="me2">replace</span></span></span> ，则准确设置文件权限为 <span class="t-c"><span class="mw-geshi cpp source-cpp">prms <span class="sy3">&</span> <a href="cpp-filesystem-perms.html"><span class="kw2237">std::<span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">mask</span></span></a></span></span> （表示应用 <code>prms</code> 的每个合法位）</li>
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<li>若 <code>opts</code> 是 <span class="t-c"><span class="mw-geshi cpp source-cpp">perm_options<span class="sy4">::</span><span class="me2">add</span></span></span> ，则准确设置文件权限为 <span class="t-c"><span class="mw-geshi cpp source-cpp">status<span class="br0">(</span>p<span class="br0">)</span>.<span class="me1">permissions</span><span class="br0">(</span><span class="br0">)</span> <span class="sy3">|</span> <span class="br0">(</span>prms <span class="sy3">&</span> perms<span class="sy4">::</span><span class="me2">mask</span><span class="br0">)</span></span></span> （表示每个设于 <code>prms</code> 却不在当前文件权限中的合法位被添加到文件权限）</li>
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<li>若 <code>opts</code> 是 <span class="t-c"><span class="mw-geshi cpp source-cpp">perm_options<span class="sy4">::</span><span class="me2">remove</span></span></span> ，则准确设置文件权限为 <span class="t-c"><span class="mw-geshi cpp source-cpp">status<span class="br0">(</span>p<span class="br0">)</span>.<span class="me1">permissions</span><span class="br0">(</span><span class="br0">)</span> <span class="sy3">&</span> ~<span class="br0">(</span>prms <span class="sy3">&</span> perms<span class="sy4">::</span><span class="me2">mask</span><span class="br0">)</span></span></span> （表示每个 <code>prms</code> 中清除却设于当前文件权限中的有效位从文件权限被清除）</li>
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</ul>
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<p><code>opts</code> 要求 <code>replace</code> 、 <code>add</code> 或 <code>remove</code> 中有且仅有一者被设置。</p>
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<p>不抛出重载在错误时无特殊行动。</p>
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<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">参数</span></h3>
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<table class="t-par-begin">
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<tr class="t-par">
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<td>p</td>
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<td>-</td>
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<td>要检验的路劲</td>
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</tr>
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<tr class="t-par">
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<td>prms</td>
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<td>-</td>
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<td>要设置、添加或移除的权限</td>
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</tr>
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<tr class="t-par">
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<td>opts</td>
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<td>-</td>
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<td>控制此函数所采用行动的选项</td>
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</tr>
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<tr class="t-par">
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<td>ec</td>
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<td>-</td>
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<td>不抛出重载中报告错误的输出参数</td>
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</tr>
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</table>
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<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">返回值</span></h3>
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<p>（无）</p>
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<h3><span class="mw-headline" id=".E5.BC.82.E5.B8.B8">异常</span></h3>
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<p>不接受 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-error-error_code.html"><span class="kw877">std::<span class="me2">error_code</span></span></a><span class="sy3">&</span></span></span> 参数的重载在底层 OS API 错误时抛出 <a href="cpp-filesystem-filesystem_error.html"><tt>filesystem_error</tt></a> ，以第一 path 参数 <code>p</code> 和作为错误码参数的 OS 错误码构造。若 OS API 调用失败，则接受 <span class="t-c"><span class="mw-geshi cpp source-cpp"><a href="cpp-error-error_code.html"><span class="kw877">std::<span class="me2">error_code</span></span></a><span class="sy3">&</span></span></span> 参数的重载设置该参数为 OS API 错误码，而若不出现错误则执行 <span class="t-c"><span class="mw-geshi cpp source-cpp">ec.<span class="me1">clear</span><span class="br0">(</span><span class="br0">)</span></span></span> 。若内存分配失败，则任何不标记为 <code>noexcept</code> 的重载可能抛出 <span class="t-lc"><a href="cpp-memory-new-bad_alloc.html">std::bad_alloc</a></span> 。</p>
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<h3><span class="mw-headline" id=".E6.B3.A8.E6.84.8F">注意</span></h3>
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<p>权限不必用位实现，但概念上用该方式处理它们。</p>
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<p>某些系统上某些权限位可能被忽略，而更改某些位可能自动影响其他（例如在无拥有者/群/全体区别的平台上，设置三者任一部分都会写入三者全体的位集）</p>
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<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
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<div class="t-example">
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<div class="t-example-live-link"></div>
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
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<div class="cpp source-cpp">
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<pre class="de1"><span class="co2">#include <fstream></span>
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<span class="co2">#include <bitset></span>
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<span class="co2">#include <iostream></span>
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<span class="co2">#include <filesystem></span>
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<span class="kw1">namespace</span> fs <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">filesystem</span><span class="sy4">;</span>
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<span class="kw4">void</span> demo_perms<span class="br0">(</span>fs<span class="sy4">::</span><span class="me2">perms</span> p<span class="br0">)</span>
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<span class="br0">{</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="br0">(</span><span class="br0">(</span>p <span class="sy3">&</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">owner_read</span><span class="br0">)</span> <span class="sy3">!</span><span class="sy1">=</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">none</span> <span class="sy4">?</span> <span class="st0">"r"</span> <span class="sy4">:</span> <span class="st0">"-"</span><span class="br0">)</span>
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<span class="sy1"><<</span> <span class="br0">(</span><span class="br0">(</span>p <span class="sy3">&</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">owner_write</span><span class="br0">)</span> <span class="sy3">!</span><span class="sy1">=</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">none</span> <span class="sy4">?</span> <span class="st0">"w"</span> <span class="sy4">:</span> <span class="st0">"-"</span><span class="br0">)</span>
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<span class="sy1"><<</span> <span class="br0">(</span><span class="br0">(</span>p <span class="sy3">&</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">owner_exec</span><span class="br0">)</span> <span class="sy3">!</span><span class="sy1">=</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">none</span> <span class="sy4">?</span> <span class="st0">"x"</span> <span class="sy4">:</span> <span class="st0">"-"</span><span class="br0">)</span>
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<span class="sy1"><<</span> <span class="br0">(</span><span class="br0">(</span>p <span class="sy3">&</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">group_read</span><span class="br0">)</span> <span class="sy3">!</span><span class="sy1">=</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">none</span> <span class="sy4">?</span> <span class="st0">"r"</span> <span class="sy4">:</span> <span class="st0">"-"</span><span class="br0">)</span>
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<span class="sy1"><<</span> <span class="br0">(</span><span class="br0">(</span>p <span class="sy3">&</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">group_write</span><span class="br0">)</span> <span class="sy3">!</span><span class="sy1">=</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">none</span> <span class="sy4">?</span> <span class="st0">"w"</span> <span class="sy4">:</span> <span class="st0">"-"</span><span class="br0">)</span>
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<span class="sy1"><<</span> <span class="br0">(</span><span class="br0">(</span>p <span class="sy3">&</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">group_exec</span><span class="br0">)</span> <span class="sy3">!</span><span class="sy1">=</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">none</span> <span class="sy4">?</span> <span class="st0">"x"</span> <span class="sy4">:</span> <span class="st0">"-"</span><span class="br0">)</span>
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<span class="sy1"><<</span> <span class="br0">(</span><span class="br0">(</span>p <span class="sy3">&</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">others_read</span><span class="br0">)</span> <span class="sy3">!</span><span class="sy1">=</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">none</span> <span class="sy4">?</span> <span class="st0">"r"</span> <span class="sy4">:</span> <span class="st0">"-"</span><span class="br0">)</span>
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<span class="sy1"><<</span> <span class="br0">(</span><span class="br0">(</span>p <span class="sy3">&</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">others_write</span><span class="br0">)</span> <span class="sy3">!</span><span class="sy1">=</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">none</span> <span class="sy4">?</span> <span class="st0">"w"</span> <span class="sy4">:</span> <span class="st0">"-"</span><span class="br0">)</span>
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<span class="sy1"><<</span> <span class="br0">(</span><span class="br0">(</span>p <span class="sy3">&</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">others_exec</span><span class="br0">)</span> <span class="sy3">!</span><span class="sy1">=</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">none</span> <span class="sy4">?</span> <span class="st0">"x"</span> <span class="sy4">:</span> <span class="st0">"-"</span><span class="br0">)</span>
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<span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span>
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<span class="br0">}</span>
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<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
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<span class="br0">{</span>
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<a href="cpp-io-basic_ofstream.html"><span class="kw1733">std::<span class="me2">ofstream</span></span></a><span class="br0">(</span><span class="st0">"test.txt"</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// 创建文件</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"Created file with permissions: "</span><span class="sy4">;</span>
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demo_perms<span class="br0">(</span>fs<span class="sy4">::</span><span class="me2">status</span><span class="br0">(</span><span class="st0">"test.txt"</span><span class="br0">)</span>.<span class="me1">permissions</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
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fs<span class="sy4">::</span><span class="me2">permissions</span><span class="br0">(</span><span class="st0">"test.txt"</span>,
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fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">owner_all</span> <span class="sy3">|</span> fs<span class="sy4">::</span><span class="me2">perms</span><span class="sy4">::</span><span class="me2">group_all</span>,
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fs<span class="sy4">::</span><span class="me2">perm_options</span><span class="sy4">::</span><span class="me2">add</span><span class="br0">)</span><span class="sy4">;</span>
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<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> <span class="st0">"After adding o+rwx and g+rwx: "</span><span class="sy4">;</span>
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demo_perms<span class="br0">(</span>fs<span class="sy4">::</span><span class="me2">status</span><span class="br0">(</span><span class="st0">"test.txt"</span><span class="br0">)</span>.<span class="me1">permissions</span><span class="br0">(</span><span class="br0">)</span><span class="br0">)</span><span class="sy4">;</span>
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fs<span class="sy4">::</span><span class="me2">remove</span><span class="br0">(</span><span class="st0">"test.txt"</span><span class="br0">)</span><span class="sy4">;</span>
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<span class="br0">}</span></pre></div>
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</div>
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<p>可能的输出：</p>
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<div dir="ltr" class="mw-geshi" style="text-align: left;">
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<div class="text source-text">
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<pre class="de1">Created file with permissions: rw-r--r--
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After adding o+rwx and g+wrx: rwxrwxr--</pre></div>
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</div>
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</div>
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<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
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<table class="t-dsc-begin">
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<tr class="t-dsc">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-filesystem-perms.html"><span class="t-lines"><span>perms</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx17">(C++17)</span></span></span></div>
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</div>
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</td>
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<td>标识文件系统权限<br />
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<span class="t-mark">(枚举)</span></td>
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</tr>
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<tr class="t-dsc">
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<td>
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<div class="t-dsc-member-div">
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<div><a href="cpp-filesystem-status.html"><span class="t-lines"><span>status</span><span>symlink_status</span></span></a></div>
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<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx17">(C++17)</span></span><span><span class="t-mark-rev t-since-cxx17">(C++17)</span></span></span></div>
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</div>
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</td>
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<td>确定文件属性<br />
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确定文件属性，检查符号链接目标<br />
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<span class="t-mark">(函数)</span></td>
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</tr>
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</table>
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</div>
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<div class="visualClear"></div>
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</div>
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</div>
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</div>
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</body>
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</html>
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