You probably havn't seen it yet, but I answered you in comp.lang.perl.tk

I made a fake sftp client for testing, but you can uncomment the real lines. Also, since you want to repeatedly send the same file, you didn't need the callback(unless you want to track large file progress).

#!/usr/bin/perl
use strict;
use warnings;
use Tk;
use Net::SFTP::Foreign;
use threads;
use threads::shared;

my $user = 'jlahowet';
my $server = 'mistral.unl.edu';
my $lcl = '/home/deadpickle/Desktop/Virtual Cockpit/uavposition';
my $rmt = '/home/jlahowet/UAV/COORDS/uavposition';


my $go:shared = 0;
#my $monitor:shared = 0;
my $die:shared = 0;
my $progress:shared = 0;
my @setup = ($user, $server, $lcl, $rmt);
#start thread before any Tk code
my $thr = threads->new(\&sftp, @setup);


#now setup Tk
my $mw = MainWindow->new();
$mw->protocol('WM_DELETE_WINDOW' => sub { &clean_exit }); 
$mw->configure(-title => 'VIRTUAL COCKPIT:SFTP', -background =>'blue')
+;
$mw->geometry('+400+300');
#User entry
my $usr = $mw->Frame(-relief => 'groove', -borderwidth => 3, -backgrou
+nd => 'blue')->pack(-side => 'top', -fill => 'x');
my $usrlbl = $usr->Label(-text => 'Username', -background => 'blue', -
+foreground => 'white')->pack(-side => 'left');
my $usreny = $usr->Entry(-width=> 10, -textvariable => \$user)->pack(-
+side => 'left', -pady => 3);
#Server entry
my $svr = $mw->Frame(-relief => 'groove', -borderwidth => 3, -backgrou
+nd => 'blue')->pack(-side => 'top', -fill => 'x');
my $svrlbl = $svr->Label(-text => 'Server', -background => 'blue', -fo
+reground => 'white')->pack(-side => 'left');
my $svreny = $svr->Entry(-width=> 15, -textvariable => \$server)->pack
+(-side => 'left', -pady => 3);
#File locations
my $loc = $mw->Frame(-relief => 'groove', -borderwidth => 3, -backgrou
+nd => 'blue')->pack(-side => 'top', -fill => 'x');
my $lcllbl = $loc->Label(-text => 'Local', -background => 'blue', -for
+eground => 'white')->pack(-side => 'left');
my $lcleny = $loc->Entry(-width=> 25, -textvariable => \$lcl)->pack(-s
+ide => 'left', -pady => 3);
my $rmtlbl = $loc->Label(-text => 'Remote', -background => 'blue', -fo
+reground => 'white')->pack(-side => 'left');
my $rmteny = $loc->Entry(-width=> 25, -textvariable => \$rmt)->pack(-s
+ide => 'left', -pady => 3);
#Connect button

my $btn = $mw->Button(-text => 'Connect', 
            -background => 'gray', 
        -command => \&sub1)
        ->pack(-side => 'bottom', -padx => 3, -pady => 3, -anchor => '
+e');

# to monitor file count, needs a timer to update
# from thread
my $val = 0;
my $label = $mw->Label(
         -width => 50,
         -textvariable => \$val )->pack(-side => 'bottom', -padx => 3,
+ -pady => 3, -anchor => 'w');


my $timer = $mw->repeat(10,sub{
              $val = $progress;
             });


MainLoop;

sub sub1 {
    if($btn->cget(-text) eq 'Connect'){
        $go = 1;
        $btn->configure(-text=> 'Stop');
        #$monitor = 0;
    }
    else{
        $go = 0;
        $btn->configure(-text=> 'Connect');
        #$monitor = 1;
    }
    print "go = $go\n";
}


sub sftp{
    $|++; 
      # setup your sftp connection 
    my $host = $_[1];
    my $usrname = $_[0];
    my $port = 22;
    my $seconds = 20;
    my %args = (user=>$usrname, port=>$port, timeout=>$seconds);
    my $local = $_[2];
    my $remote = $_[3];

# commented out to skip actual sftp use
#    my $sftp = Net::SFTP::Foreign->new($host, %args);
        my $sftp;
    print "sftp connected\n";


      #now go into a waiting loop, where you wait for
      #$go to be 1
      #when $go = 1, the sftp will keep sending the file
      
      #the only way to break out is to set $die=1


    while(1){
       if($die == 1){ goto END }; 
      
       # the go loop     
          if ( $go == 1 ){

            for(;;){
#                $sftp->put("$local", "$remote");
              print "fake file being sent\n";

                $progress++; 
                sleep 2;
                if($go == 0){last}
                if($die == 1){ goto END }; 
               }
  
             $go = 0; #turn off self before returning      
         }else { sleep 1 } # sleep if $go == 0
        # end of go loop

    }  #end of while loop

END:
undef $sftp;
print "sftp stopped thread ending\n";

}


sub clean_exit{
 $timer->cancel;

 my @running_threads = threads->list;
  if (scalar(@running_threads) < 1){print "\nFinished\n";exit}
  else{
     $die = 1;
     $thr->join;
     exit;
  }
}
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