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English
The first parameter of the ftp_site function is the SITE command, which must follow the specific format expected by the FTP server. FTP servers often provide different SITE command options depending on the operating system. For instance, UNIX systems may support commands like SITE CHMOD or SITE LIST. As different FTP servers have unique command syntaxes and parameter requirements, an incorrectly formatted command will trigger an error response from the server and result in execution failure.
<span><span><span class="hljs-variable">$ftp_conn</span></span><span> = </span><span><span class="hljs-title function_ invoke__">ftp_connect</span></span><span>(</span><span><span class="hljs-string">"ftp.example.com"</span></span><span>);
</span><span><span class="hljs-title function_ invoke__">ftp_login</span></span><span>(</span><span><span class="hljs-variable">$ftp_conn</span></span><span>, </span><span><span class="hljs-string">"username"</span></span><span>, </span><span><span class="hljs-string">"password"</span></span><span>);
</span><span><span class="hljs-title function_ invoke__">ftp_site</span></span><span>(</span><span><span class="hljs-variable">$ftp_conn</span></span><span>, </span><span><span class="hljs-string">"CHMOD 777 somefile.txt"</span></span><span>); </span><span><span class="hljs-comment">// Correct command</span></span><span>
</span><span><span class="hljs-title function_ invoke__">ftp_site</span></span><span>(</span><span><span class="hljs-variable">$ftp_conn</span></span><span>, </span><span><span class="hljs-string">"CHMOD777 somefile.txt"</span></span><span>); </span><span><span class="hljs-comment">// Incorrect format</span></span><span>
</span></span>In the second example, the command CHMOD777 is improperly formatted, causing the FTP server to fail to interpret it correctly and resulting in execution failure.
The SITE commands supported by an FTP server depend on its configuration and operating system. Some servers may not support certain commands or may reject specific options due to current configuration restrictions. If an unsupported command or parameter is used, the ftp_site function will return FALSE.
<span><span><span class="hljs-title function_ invoke__">ftp_site</span></span><span>(</span><span><span class="hljs-variable">$ftp_conn</span></span><span>, </span><span><span class="hljs-string">"SITE SETMODE 755"</span></span><span>); </span><span><span class="hljs-comment">// Suppose this command is not supported</span></span><span>
</span></span>In the example above, SITE SETMODE might not be recognized by the server. Since different FTP implementations vary, sending an unsupported command will result in failure.
The second parameter of ftp_site defines the specific command and action. If this parameter is incomplete or missing required parts, the FTP server may not understand it, causing failure. For instance, the SITE CHMOD command requires both a permission value and a file path. If either is missing, execution will fail.
<span><span><span class="hljs-title function_ invoke__">ftp_site</span></span><span>(</span><span><span class="hljs-variable">$ftp_conn</span></span><span>, </span><span><span class="hljs-string">"SITE CHMOD"</span></span><span>); </span><span><span class="hljs-comment">// Missing permission and path</span></span><span>
</span><span><span class="hljs-title function_ invoke__">ftp_site</span></span><span>(</span><span><span class="hljs-variable">$ftp_conn</span></span><span>, </span><span><span class="hljs-string">"SITE CHMOD 777"</span></span><span>); </span><span><span class="hljs-comment">// Missing file path</span></span><span>
</span></span>Both examples above lack essential command parameters, causing ftp_site to fail.
Sometimes, ftp_site may fail due to incorrect parameter types (e.g., passing a number instead of a string). Although the function expects string inputs, some improperly formatted or invalid content may prevent the FTP server from recognizing the command.
<span><span><span class="hljs-title function_ invoke__">ftp_site</span></span><span>(</span><span><span class="hljs-variable">$ftp_conn</span></span><span>, </span><span><span class="hljs-string">"SITE CHMOD 755 12345"</span></span><span>); </span><span><span class="hljs-comment">// 12345 might not be a valid file path</span></span><span>
</span></span>In this example, 12345 might not represent a valid file path or name, leading to execution failure.
In some cases, the ftp_site function fails not due to command errors, but because the user lacks the necessary permissions. For example, changing file permissions or altering directory settings may require elevated privileges. If the current FTP user lacks the required access rights, the server will deny the command.
<span><span><span class="hljs-title function_ invoke__">ftp_site</span></span><span>(</span><span><span class="hljs-variable">$ftp_conn</span></span><span>, </span><span><span class="hljs-string">"SITE CHMOD 777 sensitive_file.txt"</span></span><span>); </span><span><span class="hljs-comment">// Permission denied</span></span><span>
</span></span>In this case, the FTP user may not have the required permission to change permissions on sensitive_file.txt, causing the operation to fail.
Network problems are one of the most common reasons for FTP operation failures. If the client’s connection to the FTP server is unstable, or if the server response times out during command execution, the ftp_site command might not succeed.
<span><span><span class="hljs-variable">$ftp_conn</span></span><span> = </span><span><span class="hljs-title function_ invoke__">ftp_connect</span></span><span>(</span><span><span class="hljs-string">"ftp.example.com"</span></span><span>, </span><span><span class="hljs-number">21</span></span><span>, </span><span><span class="hljs-number">10</span></span><span>); </span><span><span class="hljs-comment">// Set timeout</span></span><span>
</span><span><span class="hljs-title function_ invoke__">ftp_login</span></span><span>(</span><span><span class="hljs-variable">$ftp_conn</span></span><span>, </span><span><span class="hljs-string">"username"</span></span><span>, </span><span><span class="hljs-string">"password"</span></span><span>);
</span><span><span class="hljs-title function_ invoke__">ftp_site</span></span><span>(</span><span><span class="hljs-variable">$ftp_conn</span></span><span>, </span><span><span class="hljs-string">"SITE CHMOD 777 somefile.txt"</span></span><span>); </span><span><span class="hljs-comment">// Fails due to network issue</span></span><span>
</span></span>If the network is unstable or the FTP server does not respond in time during command execution, ftp_site may fail.
When an FTP server is under heavy load, it may respond slowly or fail to process certain commands. Although this is a less common scenario, in high-traffic environments, server resources can become saturated, leading to ftp_site execution failures.
