Here is a way to do it without the call to unix tail... My
GUI does not freeze up with this code... 

Regards,
    Stacy.


my $exit = 0;
  for (;;) {
    while ($line = <MLOG>) {
      
      $main->update; 
      
      if ($line =~ m/estimate finish/) {
        $line =~ s/^\s+//; #remove leading whitespace
        $perc = (split(/\s+/, $line))[0];
        chop($perc); #get rid of the "%"
        $perc = sprintf("%3.0f", $perc);
        $progress_label -> configure(-text => "Percent completed: $per
+c%");
        $progress_scale -> set($perc);
        $main->update; } 
      elsif ($line =~ /extents written/) { $exit = 1 }
      else { next }
       
    }#end of while
    last if $exit == 1;
    seek(MLOG,0,1);
    $main->update; 
  }
  close(MLOG);
[download]