for my $outer ( qr/hi/, qr/bye/ ) {
    print grep { /$outer/ } qw/ bike hello hi /
}

##</code><code>##

my $outer = join "|", qw/ hi bye /;
print grep { /$outer/ } qw/ bike hello hi /;

##</code><code>##

$outer = join "|", qw/ hi bye /;
/($outer)/ and print $1
    for qw/ bike hello-hi hi-ho /;