132 lines
12 KiB
HTML
132 lines
12 KiB
HTML
<!DOCTYPE html>
|
|
<html lang="zh" dir="ltr" class="client-nojs" xmlns="http://www.w3.org/1999/xhtml" xml:lang="zh">
|
|
<head><meta http-equiv="x-ua-compatible" content="ie=edge">
|
|
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
|
|
<title>std::filesystem::create_hard_link</title>
|
|
<link rel="stylesheet" href="ext.css" />
|
|
<link rel="stylesheet" href="site_modules.css" />
|
|
</head>
|
|
<body class="mediawiki ltr sitedir-ltr ns-0 ns-subject page-cpp_filesystem_create_hard_link skin-cppreference2 action-view cpp-navbar">
|
|
<div id="cpp-content-base">
|
|
<div id="content"><a id="top"></a>
|
|
<h1 id="firstHeading" class="firstHeading"><span style="font-size:0.7em; line-height:130%">std::filesystem::</span>create_hard_link</h1>
|
|
<div id="bodyContent">
|
|
<div id="contentSub"><span class="subpages">< <a href="cpp.html">cpp</a>‎ | <a href="cpp-filesystem.html">filesystem</a></span></div>
|
|
<div id="mw-content-text" lang="zh" dir="ltr" class="mw-content-ltr" xml:lang="zh">
|
|
<table class="t-dcl-begin">
|
|
<tbody>
|
|
<tr class="t-dsc-header">
|
|
<td>
|
|
<div>定义于头文件 <code><a href="cpp-header-filesystem.html"><filesystem></a></code></div>
|
|
</td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
<tr class="t-dcl t-since-cxx17">
|
|
<td>
|
|
<div><span class="mw-geshi cpp source-cpp"><span class="kw4">void</span> create_hard_link<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> target,<br /></span>
|
|
<p> <span class="kw4">const</span> path<span class="sy3">&</span> std<span class="sy4">::</span><span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">link</span> <span class="br0">)</span><span class="sy4">;</span><br />
|
|
<span class="kw4">void</span> create_hard_link<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> target,<br />
|
|
<span class="kw4">const</span> path<span class="sy3">&</span> std<span class="sy4">::</span><span class="me2">filesystem</span><span class="sy4">::</span><span class="me2">link</span>,<br /></p>
|
|
<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>
|
|
</td>
|
|
<td class="t-dcl-nopad"></td>
|
|
<td><span class="t-mark-rev t-since-cxx17">(C++17 起)</span></td>
|
|
</tr>
|
|
<tr class="t-dcl-sep">
|
|
<td></td>
|
|
<td></td>
|
|
<td></td>
|
|
</tr>
|
|
</tbody>
|
|
</table>
|
|
<p>创建硬链接 <code>link</code> ，将其目标设为 <code>target</code> ，如同用 POSIX <a rel="nofollow" class="external text" href="http://pubs.opengroup.org/onlinepubs/9699919799/functions/link.html">link()</a> ：路径名 <code>target</code> 必须存在。</p>
|
|
<p>一旦创建， <code>link</code> 与 <code>target</code> 就是指代同一文件的二个逻辑名（它们<a href="cpp-filesystem-equivalent.html">等价</a>）。即使原名 <code>target</code> 被删除，文件也会继续存在，并可以 <code>link</code> 访问。</p>
|
|
<h3><span class="mw-headline" id=".E5.8F.82.E6.95.B0">参数</span></h3>
|
|
<table class="t-par-begin">
|
|
<tr class="t-par">
|
|
<td>target</td>
|
|
<td>-</td>
|
|
<td>要链接到的文件或目录名</td>
|
|
</tr>
|
|
<tr class="t-par">
|
|
<td>link</td>
|
|
<td>-</td>
|
|
<td>新硬链接的路径</td>
|
|
</tr>
|
|
<tr class="t-par">
|
|
<td>ec</td>
|
|
<td>-</td>
|
|
<td>不抛出重载中报告错误的输出参数</td>
|
|
</tr>
|
|
</table>
|
|
<h3><span class="mw-headline" id=".E8.BF.94.E5.9B.9E.E5.80.BC">返回值</span></h3>
|
|
<p>（无）</p>
|
|
<h3><span class="mw-headline" id=".E5.BC.82.E5.B8.B8">异常</span></h3>
|
|
<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>target</code>，第二 path 参数 <code>link</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>
|
|
<h3><span class="mw-headline" id=".E6.B3.A8.E6.84.8F">注意</span></h3>
|
|
<p>一些操作系统完全不支持硬链接，或仅对常规文件支持。</p>
|
|
<p>某些文件系统不支持符号链接，无关乎操作系统，例如用于某些内存卡和闪存驱动器的 FAT 系统。</p>
|
|
<p>某些文件系统限制每个文件的链接数。</p>
|
|
<p>典型的到目录的硬链接对超级用户限制。</p>
|
|
<p>典型的硬链接不能跨越文件系统边界。</p>
|
|
<p>特殊路径名点（<span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="st0">"."</span></span></span>）是到其亲目录的硬链接。特殊路径名双点（<span class="t-c"><span class="mw-geshi cpp source-cpp"><span class="st0">".."</span></span></span>）是到其亲目录的亲目录的硬链接。</p>
|
|
<h3><span class="mw-headline" id=".E7.A4.BA.E4.BE.8B">示例</span></h3>
|
|
<div class="t-example">
|
|
<div class="t-example-live-link"></div>
|
|
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="cpp source-cpp">
|
|
<pre class="de1"><span class="co2">#include <iostream></span>
|
|
<span class="co2">#include <fstream></span>
|
|
<span class="co2">#include <filesystem></span>
|
|
<span class="kw1">namespace</span> fs <span class="sy1">=</span> std<span class="sy4">::</span><span class="me2">filesystem</span><span class="sy4">;</span>
|
|
|
|
<span class="kw4">int</span> main<span class="br0">(</span><span class="br0">)</span>
|
|
<span class="br0">{</span>
|
|
fs<span class="sy4">::</span><span class="me2">create_directories</span><span class="br0">(</span><span class="st0">"sandbox/subdir"</span><span class="br0">)</span><span class="sy4">;</span>
|
|
<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">"sandbox/a"</span><span class="br0">)</span>.<span class="me1">put</span><span class="br0">(</span><span class="st0">'a'</span><span class="br0">)</span><span class="sy4">;</span> <span class="co1">// 创建常规文件</span>
|
|
fs<span class="sy4">::</span><span class="me2">create_hard_link</span><span class="br0">(</span><span class="st0">"sandbox/a"</span>, <span class="st0">"sandbox/b"</span><span class="br0">)</span><span class="sy4">;</span>
|
|
fs<span class="sy4">::</span><span class="me2">remove</span><span class="br0">(</span><span class="st0">"sandbox/a"</span><span class="br0">)</span><span class="sy4">;</span>
|
|
<span class="co1">// 通过存活的硬链接读取原始文件</span>
|
|
<span class="kw4">char</span> c <span class="sy1">=</span> <a href="cpp-io-basic_ifstream.html"><span class="kw1732">std::<span class="me2">ifstream</span></span></a><span class="br0">(</span><span class="st0">"sandbox/b"</span><span class="br0">)</span>.<span class="me1">get</span><span class="br0">(</span><span class="br0">)</span><span class="sy4">;</span>
|
|
<a href="cpp-io-cout.html"><span class="kw1758">std::<span class="me2">cout</span></span></a> <span class="sy1"><<</span> c <span class="sy1"><<</span> <span class="st0">'<span class="es1">\n</span>'</span><span class="sy4">;</span>
|
|
fs<span class="sy4">::</span><span class="me2">remove_all</span><span class="br0">(</span><span class="st0">"sandbox"</span><span class="br0">)</span><span class="sy4">;</span>
|
|
<span class="br0">}</span></pre></div>
|
|
</div>
|
|
<p>输出：</p>
|
|
<div dir="ltr" class="mw-geshi" style="text-align: left;">
|
|
<div class="text source-text">
|
|
<pre class="de1">a</pre></div>
|
|
</div>
|
|
</div>
|
|
<h3><span class="mw-headline" id=".E5.8F.82.E9.98.85">参阅</span></h3>
|
|
<table class="t-dsc-begin">
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-filesystem-create_symlink.html"><span class="t-lines"><span>create_symlink</span><span>create_directory_symlink</span></span></a></div>
|
|
<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>
|
|
</div>
|
|
</td>
|
|
<td>创建一个符号链接<br />
|
|
<span class="t-mark">(函数)</span></td>
|
|
</tr>
|
|
<tr class="t-dsc">
|
|
<td>
|
|
<div class="t-dsc-member-div">
|
|
<div><a href="cpp-filesystem-hard_link_count.html"><span class="t-lines"><span>hard_link_count</span></span></a></div>
|
|
<div><span class="t-lines"><span><span class="t-mark-rev t-since-cxx17">(C++17)</span></span></span></div>
|
|
</div>
|
|
</td>
|
|
<td>返回指代特定文件的硬链接数<br />
|
|
<span class="t-mark">(函数)</span></td>
|
|
</tr>
|
|
</table>
|
|
</div>
|
|
<div class="visualClear"></div>
|
|
</div>
|
|
</div>
|
|
</div>
|
|
</body>
|
|
</html>
|