Tcl

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 Tcl Downloads

Download Chilkat for Tcl

Tcl


load ./chilkat.dll

set success 0

set ftp [new_CkFtp2]

CkFtp2_put_Hostname $ftp "ftp.example.com"
CkFtp2_put_Username $ftp "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.
CkFtp2_put_Password $ftp "myPassword"

set success [CkFtp2_Connect $ftp]
if {$success == 0} then {
    puts [CkFtp2_lastErrorText $ftp]
    delete_CkFtp2 $ftp
    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.
CkFtp2_put_RestartNext $ftp 1

#  Resume a partially-downloaded file.  Because RestartNext is set, the download continues from
#  the current local file size.
set success [CkFtp2_GetFile $ftp "public_html/bigfile.zip" "qa_output/bigfile.zip"]
if {$success == 0} then {
    puts [CkFtp2_lastErrorText $ftp]
    delete_CkFtp2 $ftp
    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 {CkFtp2_get_PartialTransfer $ftp} then {
    puts "Only part of the file was received; another resume may be needed."
} else {
    puts "The file was fully received."
}

set success [CkFtp2_Disconnect $ftp]
if {$success == 0} then {
    puts [CkFtp2_lastErrorText $ftp]
    delete_CkFtp2 $ftp
    exit
}


delete_CkFtp2 $ftp