use strict;
use warnings;
while (<DATA>) {
    my $var=$_;
    $var=~s/(.{9})/$1\n/;
    print "$var";
}

__DATA__
dgbjhdghjdfgjhd
dfgjdjfghjkdhgdfg
dgbhgdfjgjhgdfgdfg
ghgjgglhkdjghkdhgk