SFTP stands for [ssh] file transfer protocol; curiously, the pertinent Wikipedia article
[http://en.wikipedia.org/wiki/SSH_file_transfer_protocol]
refers to the operative [IETF] draft
[http://www.vandyke.com/technology/draft-ietf-secsh-filexfer.txt] 
only rather obliquely. When encountering the
term '''sftp''', one may in fact see references to two different things:

   1. the ''secure file transfer program'' client, which is a command line program that comes with OpenSSH and which is an interactive interface similar to the normal [ftp] clients one may find on their platform.

   2. the true ssh file transfer ''protocol''. http://en.wikipedia.org/wiki/SSH_file_transfer_protocol refers to this as being almost a remote file system protocol.  Full support of the protocol is more than just running ftp over SSH-2 or with an [SSL] layer.

A [vfs] module for the ssh file transfer protocol would be ''extremely cool''.

----
While there's a widespread belief that [Expect] is essentially necessary for effective automation of sftp (first sense), 
this is not true.  Several distinct approaches exist
[http://support.attachmate.com/techdocs/2126.html]
[http://www.freedownloadscenter.com/Best/sftp-automation.html]
[http://www.hiteksoftware.com/jasf/sftp-secure-file-transfer.htm]
... [[explain]]
OTOH, most of these seem to be alternative SFTP clients with built-in automation support, so for use from within Tcl the most portable solution may well be to use [Expect] (or '''sftp''' in batch mode, if that is sufficient).

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'''[BF] - 2012-02-08 16:05:18'''

This guy claims to have a solution to the FTP on TLS problem 
https://groups.google.com/group/comp.lang.tcl/browse_thread/thread/2040029cb6d9d626/4a418d988305b0e0?lnk=gst&q=ftp+ssl#4a418d988305b0e0
----
'''[gavino] - 16aug2012'''

I automated sftp login and change dir and download:<<br>>
1 without keys <<br>>
2 SSH was turned OFF on the server, so ONLY pure SFTP connections are not dropped. 
My Expect attempt failed, Net::SFTP failed since it uses SSH, which was turned off: so I used perl expect in order to script monitor the sftp server's working condition.  <<br>>
I would love to see how tcl or tcl expect would do this without keys, and without ssh: only sftp connections get handled.<<br>>
code follows:

===
#!/usr/bin/perl
use strict;
use Expect;

# Uncomment the following line if you want to see what expect is doing
#$Expect::Exp_Internal = 1;

# Uncomment the following line if you don't want to see any output from the script
#$Expect::Log_Stdout = 0;

# set your username/password here
my $sftpUsername = "gerogebush" ;
my $sftpPassword = "texas";
my $sftpServer = "bush.texas.com";
my $fileToFetch1 = "file1";
my $fileToFetch2 = "file2";
my $dir1 = "IN";
my $dir2 = "OUT";
my $timeout = 1;

# If sftp is not in your path replace with absolute path of sftp program
my $command = 'sftp';
my $params = ("$sftpUsername\@$sftpServer");

# Create the Expect object
my $exp = Expect->spawn($command, $params) or die "Cannot spawn sftp command \n";

# If this is the first time you are running this , expect will send "yes" to add the key
# for the sftp server to the ~/.ssh/known_hosts file else
# wait for "Password Authentication" string to show up
$exp->expect($timeout,
        ["Password Authentication"],
        ["Are you sure you want to continue connecting", sub {my $self = shift; $self->send("yes\n");}]
        );

# Wait for Password prompt to show up
#$exp->expect($timeout, ["password:"]);
$exp->expect($timeout, ["password:"]);
#$exp->expect($timeout, ["Password:"]);

# Sent the sftp password
$exp->send("$sftpPassword\n");

# Wait for sftp prompt
$exp->expect($timeout, ["sftp>"]);

$exp->send("cd $dir1\n");

# Wait for sftp prompt
$exp->expect($timeout, ["sftp>"]);

$exp->send("get $fileToFetch1\n");

# Wait for sftp prompt
$exp->expect($timeout, ["sftp>"]);

$exp->send("cd ../$dir2\n");

# Wait for sftp prompt
$exp->expect($timeout, ["sftp>"]);

$exp->send("get $fileToFetch2\n");

# Wait for sftp prompt
$exp->expect($timeout, ["sftp>"]);

# Close ftp session
$exp->send("bye\n");

# Destroy the expect object
$exp->soft_close();
===

<<categories>> Acronym | Security