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The ftp_login function is used to authenticate a user after establishing a connection with an FTP server. It takes the FTP resource connection along with the username and password as parameters to verify whether authentication succeeds. If the authentication is successful, the server responds with a success message.
Function Prototype:
<span><span><span class="hljs-keyword">bool</span></span><span> </span><span><span class="hljs-title function_ invoke__">ftp_login</span></span><span> ( resource </span><span><span class="hljs-variable">$ftp_stream</span></span><span> , </span><span><span class="hljs-keyword">string</span></span><span> </span><span><span class="hljs-variable">$username</span></span><span> , </span><span><span class="hljs-keyword">string</span></span><span> </span><span><span class="hljs-variable">$password</span></span><span> )
</span></span>$ftp_stream: The already established FTP connection resource.
$username: The username for login.
$password: The password corresponding to the username.
Return Value:
If authentication succeeds, ftp_login returns true.
If authentication fails, ftp_login returns false.
Example Code:
<span><span><span class="hljs-variable">$ftp_connection</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-keyword">if</span></span><span> (</span><span><span class="hljs-variable">$ftp_connection</span></span><span>) {
</span><span><span class="hljs-keyword">if</span></span><span> (</span><span><span class="hljs-title function_ invoke__">ftp_login</span></span><span>(</span><span><span class="hljs-variable">$ftp_connection</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-keyword">echo</span></span><span> </span><span><span class="hljs-string">"Login successful!"</span></span><span>;
} </span><span><span class="hljs-keyword">else</span></span><span> {
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"Login failed!"</span></span><span>;
}
}
</span></span>In the example above, ftp_login returns a boolean value indicating whether the login was successful. After successful authentication, the FTP connection is in an authenticated state, allowing file transfers and other operations.
The ftp_get_option function retrieves specific options from an FTP connection. It can be called before or after authentication. Different options help developers understand the server’s configuration or connection status.
Function Prototype:
<span><span><span class="hljs-keyword">mixed</span></span><span> </span><span><span class="hljs-title function_ invoke__">ftp_get_option</span></span><span> ( resource </span><span><span class="hljs-variable">$ftp_stream</span></span><span> , </span><span><span class="hljs-keyword">int</span></span><span> </span><span><span class="hljs-variable">$option</span></span><span> )
</span></span>$ftp_stream: The established FTP connection resource.
$option: The option type to retrieve. Common options include:
FTP_TIMEOUT_SEC: Get the connection timeout value.
FTP_AUTOSEEK: Get whether auto-seek is enabled.
Return Value:
The return value of ftp_get_option depends on the requested option:
For FTP_TIMEOUT_SEC, it returns the connection timeout (in seconds).
For FTP_AUTOSEEK, it returns a boolean indicating whether auto-seek is enabled.
Example Code:
<span><span><span class="hljs-variable">$ftp_connection</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-variable">$timeout</span></span><span> = </span><span><span class="hljs-title function_ invoke__">ftp_get_option</span></span><span>(</span><span><span class="hljs-variable">$ftp_connection</span></span><span>, FTP_TIMEOUT_SEC);
</span><span><span class="hljs-keyword">echo</span></span><span> </span><span><span class="hljs-string">"Connection timeout: <span class="hljs-subst">$timeout</span></span></span><span> seconds";
</span></span>The main difference between ftp_get_option and ftp_login lies in the return values before and after authentication:
Calling ftp_get_option before authentication:
When an FTP connection is established but authentication has not been performed, ftp_get_option can still return some connection-related options such as FTP_TIMEOUT_SEC (connection timeout). However, not all options are accessible before authentication; certain authentication-related options are only available after a successful login.
Calling ftp_get_option after authentication:
Once ftp_login successfully authenticates, the FTP connection enters an authenticated state. At this point, more authentication-related options can be retrieved. For example, by calling ftp_get_option, you can confirm server-related settings, and in some cases, these options may affect subsequent file operations (such as whether passive mode is enabled during file uploads or downloads).
ftp_login and ftp_get_option are two very important PHP functions for working with FTP servers, each serving different purposes and returning different values. ftp_login handles user authentication and returns a boolean indicating success or failure; meanwhile, ftp_get_option retrieves various connection options, with return values depending on the type of option requested.
Before authentication, ftp_get_option mainly focuses on connection settings, while after authentication it can provide more details about the FTP service configuration itself. Understanding the difference between the two allows developers to interact more flexibly with FTP servers and carry out more advanced file operations and management tasks.
