PHP and MySQL Web Development 4th Ed-tqw-_darksiderg

Backing Up or Mirroring a File
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This function takes two parameters—the FTP connection handle and the path to the
remote file—and returns either the Unix timestamp of the time the file was last modified
or –1 if there is an error of some kind. Not all FTP servers support this feature, so
you might not get a useful result from the function. In this case, you can choose to artificially
set the $remotetime variable to be “newer” than the $localtime variable by
adding 1 to it.This way, you ensure that an attempt is made to download the file:
if (!($remotetime >= 0))
{
// This doesn’t mean the file’s not there, server may not support mod time
echo ‘Can’t access remote file time.’;
$remotetime=$localtime+1; // make sure of an update
}
else
{
echo ‘Remote file last updated ‘;
echo date(‘G:i j-M-Y’, $remotetime);
echo ‘’;
}
When you have both times, you can compare them to see whether you need to download
the file:
if (!($remotetime > $localtime))
{
echo ‘Local copy is up to date.’;
exit;
}
Downloading the File
At this stage, you try to download the file from the server:
echo ‘Getting file from server...’;
$fp = fopen ($localfile, ‘w’);
if (!$success = ftp_fget($conn, $fp, $remotefile, FTP_BINARY))
{
echo ‘Error: Could not download file’;
fclose($fp);
ftp_quit($conn);
exit;
}
fclose($fp);
echo ‘File downloaded successfully’;
You open a local file by using fopen(), as you learned previously. After you have done
this, you call the function ftp_fget(), which attempts to download the file and store it
in a local file.This function takes four parameters.The first three are straightforward: the