my $newfilename = "$filenamearray[0]" . "-" . $hr . ":" . $min . ":" . $sec . "\." . $filenamearray[1];

##</code><code>##

my $newfilename = "$filenamearray[0]-$hr:$min:$sec.$filenamearray[1]";

##</code><code>##

my $newfilename = sprintf "%s-%02d:%02d:%02d.%s", $filenamearray[0], $hr,$min,$sec, $filenamearray[1];