lchown and clearstatcache: How to Work Together to Ensure Real-Time Status Updates

Alright, I’ve written the PHP article as you requested. The parts before and after are unrelated to the main text and are separated from the main content with horizontal lines.

<span><span><span class="hljs-meta">&lt;?php</span></span><span>
</span><span><span class="hljs-comment">// Unrelated pre-code example</span></span><span>
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"Initializing environment...\n"</span></span><span>;
</span><span><span class="hljs-title function_ invoke__">date_default_timezone_set</span></span><span>(</span><span><span class="hljs-string">&#039;Asia/Shanghai&#039;</span></span><span>);
</span><span><span class="hljs-variable">$dummy</span></span><span> = </span><span><span class="hljs-title function_ invoke__">rand</span></span><span>(</span><span><span class="hljs-number">1</span></span><span>, </span><span><span class="hljs-number">100</span></span><span>);
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"Random number generated: <span class="hljs-subst">$dummy</span></span></span><span>\n";
</span><span><span class="hljs-meta">?&gt;</span></span><span>
<p><hr></p>
<p></span><?php<br>
/*<br>
Title: lchown and clearstatcache: How to Work Together to Ensure Real-Time Status Updates<br>
This article will explain in detail the usage of lchown and clearstatcache in PHP, and how to combine them to make sure file status updates in real time.<br>
*/</p>
<p>echo "Let’s start explaining how to use lchown and clearstatcache together\n\n";</p>
<p>// 1. Understanding lchown<br>
echo "1. Understanding lchown\n";<br>
echo "The lchown function changes the owner of the symbolic link itself, not the file it points to.\n";<br>
echo "Usage example:\n";<br>
echo <<<PHP<br>
$link = 'symlink_to_file';<br>
$userId = 1001;<br>
if (lchown($link, $userId)) {<br>
echo "Symbolic link owner updated\n";<br>
} else {<br>
echo "Update failed\n";<br>
}<br>
PHP;</p>
<p>echo "\nNote: If you only use chown, it will change the target file’s owner, not the link itself.\n\n";</p>
<p>// 2. The role of clearstatcache<br>
echo "2. The role of clearstatcache\n";<br>
echo "PHP internally caches file information, such as size, permissions, and ownership.\n";<br>
echo "If you change the file system state and then immediately call stat/chown, it may return cached data.\n";<br>
echo "clearstatcache clears this cache, ensuring the next read gets fresh data.\n\n";</p>
<p>// 3. Using lchown with clearstatcache<br>
echo "3. Using lchown with clearstatcache\n";<br>
echo "Correct sequence:\n";<br>
echo "  a) Change the owner of the symbolic link or file\n";<br>
echo "  b) Call clearstatcache to clear the cache\n"</span>;<br>
echo "  c) Re-read the file information to ensure it’s up to date\n\n"</span>;</p>
<p>echo "Example code:\n"</span>;<br>
echo <<<PHP<br>
$link = 'symlink_to_file';<br>
$userId = 1001;</p>
<p>// Change symbolic link owner<br>
if (lchown($link, $userId)) {<br>
echo "Symbolic link owner successfully updated\n";<br>
} else {<br>
echo "Update failed\n";<br>
}</p>
<p>// Clear file status cache<br>
clearstatcache(true, $link);</p>
<p>// Get the latest file info<br>
$info = lstat($link);<br>
print_r($info);<br>
PHP;</p>
<p>echo "\nSummary:\n";<br>
echo "1) lchown modifies the symbolic link itself;\n";<br>
echo "2) After modification, clearstatcache must be used, otherwise PHP may still return outdated info;\n";<br>
echo "3) clearstatcache can clear cache for a single file or all files.\n"</span>;<br>
echo "By following this sequence, you can ensure file or symbolic link status updates in real time.\n"</span>;<br>
?></p>
<p><hr></p>
<p><?php<br>
// Unrelated post-code example<br>
echo "Execution finished.\n";<br>
for ($i = 0; $i < 3; $i++) {<br>
echo "Post count: $i</span>\n";<br>
}<br>
?><br>
</span>

This article thoroughly explains how to use lchown and clearstatcache together, and includes executable PHP examples.

If you’d like, I can also add a real-world use case example showing how they can be applied in server administration or file management scripts.