my $len = length($tmp_line);
my $pos = 0;
my $tab = 5;
while ( my $s = unpack("x$pos A4000", $tmp_line) ) { 
    $tab--;
    print $frontend "$s\t";
    $pos += 4000;
    last if $pos >= $len;
}   
print $frontend "\t" x $tab;
print $frontend "\n";