ftp_nb_continue() function in PHP

The ftp_nb_continue() function continues to receive or send a file to the FTP server in non-blocking mode. This function is used with non-blocking FTP operations to check the status and continue the transfer process.

Syntax

ftp_nb_continue($ftp_connection);

Parameters

• ftp_connection − The FTP connection resource created by ftp_connect().

Return Value

The ftp_nb_continue() function returns one of the following constants −

• FTP_FAILED − The transfer failed

• FTP_FINISHED − The transfer completed successfully

• FTP_MOREDATA − The transfer is still in progress

Example

The following example shows how to use ftp_nb_continue() with ftp_nb_get() to download a file in non-blocking mode. Here, "local_file.txt" is the local destination file, and "remote_file.txt" is the file on the FTP server −

<?php
    // Establish FTP connection
    $ftp_conn = ftp_connect("ftp.example.com");
    ftp_login($ftp_conn, "username", "password");
    
    // Start non-blocking download
    $result = ftp_nb_get($ftp_conn, "local_file.txt", "remote_file.txt", FTP_BINARY);
    
    while ($result == FTP_MOREDATA) {
        // Download continues
        echo "File is downloading...<br>";
        $result = ftp_nb_continue($ftp_conn);
    }
    
    if ($result != FTP_FINISHED) {
        echo "Download failed!<br>";
        exit(1);
    } else {
        echo "Download completed successfully!<br>";
    }
    
    ftp_close($ftp_conn);
?>

File is downloading...
File is downloading...
Download completed successfully!

Key Points

• This function only works with non-blocking FTP operations like ftp_nb_get() and ftp_nb_put()

• Use it in a loop to continuously check the transfer status

• Always check the return value to determine if the transfer completed, failed, or needs to continue

Conclusion

The ftp_nb_continue() function is essential for managing non-blocking FTP transfers, allowing you to monitor progress and handle large file transfers efficiently without blocking script execution.