Perl

Resume an Interrupted FTP Transfer

Demonstrates the RestartNext and PartialTransfer properties, which request that the next transfer resume from existing content and report whether a download was incomplete.

Note: The local paths are relative to the application's current working directory. Absolute paths may also be used. Supply the paths appropriate to your own environment.

Background: For a large transfer over a flaky link, restarting from zero after a drop is wasteful. Setting RestartNext makes the next download continue from the current local file size (and the next upload from the remote size); the flag is consumed by that one transfer and then reset. Afterward PartialTransfer tells you whether the download got only part of the file — the signal to set RestartNext again and resume once more.

Chilkat Perl Downloads

Download Chilkat for Perl

Perl

use chilkat();

$success = 0;

$ftp = chilkat::CkFtp2->new();

$ftp->put_Hostname("ftp.example.com");
$ftp->put_Username("myFtpLogin");

#  Normally you would not hard-code the password in source.  You should instead obtain it
#  from an interactive prompt, environment variable, or a secrets vault.
$ftp->put_Password("myPassword");

$success = $ftp->Connect();
if ($success == 0) {
    print $ftp->lastErrorText() . "\r\n";
    exit;
}

#  RestartNext requests that the NEXT transfer resume from existing content rather than starting
#  over.  It is consumed by that transfer and then automatically reset.
$ftp->put_RestartNext(1);

#  Resume a partially-downloaded file.  Because RestartNext is set, the download continues from
#  the current local file size.
$success = $ftp->GetFile("public_html/bigfile.zip","qa_output/bigfile.zip");
if ($success == 0) {
    print $ftp->lastErrorText() . "\r\n";
    exit;
}

#  PartialTransfer indicates whether the most recent download received some, but not all, of the
#  remote file -- distinguishing a mid-transfer failure from other outcomes.
if ($ftp->get_PartialTransfer()) {
    print "Only part of the file was received; another resume may be needed." . "\r\n";
}
else {
    print "The file was fully received." . "\r\n";
}

$success = $ftp->Disconnect();
if ($success == 0) {
    print $ftp->lastErrorText() . "\r\n";
    exit;
}