ftp_nb_get
    (PHP 4 >= 4.3.0, PHP 5)
ftp_nb_get -- Retrieves a file from the FTP server and writes it to a local file (non-blocking)
Description
int 
ftp_nb_get ( resource ftp_stream, string local_file, string remote_file, int mode [, int resumepos] )
   ftp_nb_get() retrieves a remote file from the FTP server,
   and saves it into a local file. 
  
   The difference between this function and ftp_get() is that
   this function retrieves the file asynchronously, so your program can perform 
   other operations while the file is being downloaded.
  
Parameters
   
- ftp_stream
 
       The link identifier of the FTP connection.
      
- local_file
 
       The local file path (will be overwritten if the file already exists).
      
- remote_file
 
       The remote file path.
      
- mode
 
       The transfer mode. Must be either FTP_ASCII or
       FTP_BINARY.
      
- resumepos
 
 
  Return Values
   Returns FTP_FAILED or FTP_FINISHED
   or FTP_MOREDATA.
  
Examples
   
Example 1. ftp_nb_get() example 
<?php
  // Initate the download $ret = ftp_nb_get($my_connection, "test", "README", FTP_BINARY); while ($ret == FTP_MOREDATA) {        // Do whatever you want    echo ".";
     // Continue downloading...    $ret = ftp_nb_continue($my_connection); } if ($ret != FTP_FINISHED) {    echo "There was an error downloading the file...";    exit(1); } ?>
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   Example 2. Resuming a download with ftp_nb_get() 
<?php
  // Initate  $ret = ftp_nb_get($my_connection, "test", "README", FTP_BINARY,                        filesize("test")); // OR: $ret = ftp_nb_get($my_connection, "test", "README",  //                           FTP_BINARY, FTP_AUTORESUME); while ($ret == FTP_MOREDATA) {        // Do whatever you want    echo ".";
     // Continue downloading...    $ret = ftp_nb_continue($my_connection); } if ($ret != FTP_FINISHED) {    echo "There was an error downloading the file...";    exit(1); } ?>
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   Example 3. 
     Resuming a download at position 100 to a new
     file with ftp_nb_get()
     
<?php
  // Disable Autoseek ftp_set_option($my_connection, FTP_AUTOSEEK, false);
  // Initiate $ret = ftp_nb_get($my_connection, "newfile", "README", FTP_BINARY, 100); while ($ret == FTP_MOREDATA) {
     /* ... */        // Continue downloading...    $ret = ftp_nb_continue($my_connection); } ?>
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   In the example above, newfile is 100 bytes smaller
   than README on the FTP server because we started
   reading at offset 100. If we didn't disable 
   FTP_AUTOSEEK, the first 100 bytes of
   newfile would be '\0'.