open ( my $input_fh, "<", $input_file );
open ( my $output_fh, ">", $output_file );
foreach my $line ( <$input_fh> )
{
  unless ( $line =~ m/\A\s*\Z/ )
  {
    $line =~ s/(GL\d{6}))\d+/$1/;
    print $output_fh $line;
  }
}
close ( $input_fh );
close ( $output_fh );