263 lines
23 KiB
HTML
263 lines
23 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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<title>std::filesystem::perms</title>
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<link rel="stylesheet" href="ext.css" />
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<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_filesystem_perms skin-cppreference2 action-view cpp-navbar">
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<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::filesystem::</span>perms</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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<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></td>
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<td></td>
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<div><span class="mw-geshi cpp source-cpp"><span class="kw2">enum</span> <span class="kw1">class</span> perms<span class="sy4">;</span></span></div>
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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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<p>此类型代表文件访问权限。 <code>perms</code> 满足<a href="cpp-named_req-BitmaskType.html"><span style="font-style:italic">位掩码类型</span> <span style="font-family: Georgia, 'DejaVu Serif', serif; font-style:italic">(BitmaskType)</span></a> 的要求(表示位运算符 <span class="t-c"><span class="mw-geshi cpp source-cpp">operator<span class="sy3">&</span></span></span> 、 <span class="t-c"><span class="mw-geshi cpp source-cpp">operator<span class="sy3">|</span></span></span> 、 <span class="t-c"><span class="mw-geshi cpp source-cpp">operator<span class="sy3">^</span></span></span> 、 <span class="t-c"><span class="mw-geshi cpp source-cpp">operator~</span></span> 、 <span class="t-c"><span class="mw-geshi cpp source-cpp">operator<span class="sy3">&</span><span class="sy1">=</span></span></span> 、 <span class="t-c"><span class="mw-geshi cpp source-cpp">operator<span class="sy3">|</span><span class="sy1">=</span></span></span> 及 <span class="t-c"><span class="mw-geshi cpp source-cpp">operator<span class="sy3">^</span><span class="sy1">=</span></span></span> 对此类型定义)</p>
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<p>访问权限模仿 <a rel="nofollow" class="external text" href="http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/sys_stat.h.html">POSIX 权限位</a>,而且任何单独的文件权限(由 <a href="cpp-filesystem-status.html">status</a> 报告)都是下列位的某些组合:</p>
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<h3><span class="mw-headline" id=".E6.88.90.E5.91.98.E5.B8.B8.E9.87.8F">成员常量</span></h3>
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<table class="wikitable" style="text-align:left; font-size:85%; max-width:90em;">
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<tr>
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<th>成员常量</th>
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<th>值(八进制)</th>
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<th>POSIX 等价</th>
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<th>含义</th>
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</tr>
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<tr>
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<td><code>none</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">​<span class="nu0">0</span>​</span></span></td>
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<td></td>
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<td>未设权限位</td>
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</tr>
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<tr>
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<td><code>owner_read</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="nu8">0400</span></span></span></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">S_IRUSR</span></span></td>
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<td>文件拥有者拥有读权限</td>
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</tr>
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<tr>
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<td><code>owner_write</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="nu8">0200</span></span></span></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">S_IWUSR</span></span></td>
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<td>文件拥有者拥有写权限</td>
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</tr>
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<tr>
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<td><code>owner_exec</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="nu8">0100</span></span></span></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">S_IXUSR</span></span></td>
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<td>文件拥有着拥有执行/查找权限</td>
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</tr>
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<tr>
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<td><code>owner_all</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="nu8">0700</span></span></span></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">S_IRWXU</span></span></td>
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<td>文件拥有者拥有读、写、执行/查找权限
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<p>等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp">owner_read <span class="sy3">|</span> owner_write <span class="sy3">|</span> owner_exec</span></span></p>
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</td>
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</tr>
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<tr>
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<td><code>group_read</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="nu8">040</span></span></span></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">S_IRGRP</span></span></td>
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<td>文件用户组拥有读权限</td>
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</tr>
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<tr>
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<td><code>group_write</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="nu8">020</span></span></span></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">S_IWGRP</span></span></td>
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<td>文件用户组拥有写权限</td>
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</tr>
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<tr>
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<td><code>group_exec</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="nu8">010</span></span></span></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">S_IXGRP</span></span></td>
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<td>文件用户组拥有执行/查找权限</td>
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</tr>
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<tr>
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<td><code>group_all</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="nu8">070</span></span></span></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">S_IRWXG</span></span></td>
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<td>文件用户组拥有读、写、执行/查找权限
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<p>等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp">group_read <span class="sy3">|</span> group_write <span class="sy3">|</span> group_exec</span></span></p>
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</td>
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</tr>
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<tr>
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<td><code>others_read</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="nu8">04</span></span></span></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">S_IROTH</span></span></td>
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<td>其他用户拥有读权限</td>
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</tr>
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<tr>
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<td><code>others_write</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="nu8">02</span></span></span></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">S_IWOTH</span></span></td>
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<td>其他用户拥有写权限</td>
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</tr>
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<tr>
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<td><code>others_exec</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="nu8">01</span></span></span></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">S_IXOTH</span></span></td>
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<td>其他用户拥有执行/查找权限</td>
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</tr>
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<tr>
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<td><code>others_all</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="nu8">07</span></span></span></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">S_IRWXO</span></span></td>
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<td>其他用户拥有拥有读、写及执行/查找权限
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<p>等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp">others_read <span class="sy3">|</span> others_write <span class="sy3">|</span> others_exec</span></span></p>
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</td>
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</tr>
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<tr>
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<td><code>all</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="nu8">0777</span></span></span></td>
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<td></td>
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<td>所有用户拥有读、写及执行/查找权限
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<p>等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp">owner_all <span class="sy3">|</span> group_all <span class="sy3">|</span> others_all</span></span></p>
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</td>
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</tr>
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<tr>
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<td><code>set_uid</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="nu8">04000</span></span></span></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">S_ISUID</span></span></td>
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<td>在执行上设置用户 ID 为文件拥有者的用户 ID</td>
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</tr>
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<tr>
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<td><code>set_gid</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="nu8">02000</span></span></span></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">S_ISGID</span></span></td>
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<td>在执行上设置组 ID 为文件用户的组 ID</td>
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</tr>
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<tr>
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<td><code>sticky_bit</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="nu8">01000</span></span></span></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp">S_ISVTX</span></span></td>
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<td>实现定义的含义,不过 POSIX XSI 指定在设置于目录时,唯有文件拥有者可以删除文件,即使该目录对其他人可写(与 <span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="sy2">/</span>tmp</span></span> 一并使用)</td>
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</tr>
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<tr>
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<td><code>mask</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="nu8">07777</span></span></span></td>
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<td></td>
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<td>所有合法权限位。
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<p>等价于 <span class="t-c"><span class="mw-geshi cpp source-cpp">all <span class="sy3">|</span> set_uid <span class="sy3">|</span> set_gid <span class="sy3">|</span> sticky_bit</span></span></p>
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</td>
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</tr>
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</table>
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<p>另外,定义此类型的下列常量,它不表示权限:</p>
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<table class="wikitable" style="text-align:left; font-size:85%; max-width:90em;">
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<tr>
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<th>成员常量</th>
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<th>值(十六进制)</th>
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<th>含义</th>
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</tr>
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<tr>
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<td><code>unknown</code></td>
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<td><span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="nu12">0xFFFF</span></span></span></td>
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<td>未知权限(例如当 <a href="cpp-filesystem-file_status.html">file_status</a> 以不带权限创建时)</td>
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</tr>
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</table>
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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-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>
|
|
<tr class="t-dsc">
|
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<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-filesystem-permissions.html"><span class="t-lines"><span>permissions</span></span></a></div>
|
|
<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>修改文件访问权限<br />
|
|
<span class="t-mark">(函数)</span></td>
|
|
</tr>
|
|
</table>
|
|
</div>
|
|
<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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