my $line1 = 'CABGFE';
my $line2 = 'DBF';

say for $line1 =~ /[$line2]/g;

##</code><code>##

my @line1 = qw(C A B G F E);
my @line2 = qw(D B F);

my $line1 = join '', @line1;
my $line2 = join '', @line2;

say for $line1 =~ /[$line2]/g;