perl -wMstrict -e
"my $str = 'abcdabcdabcdabcdabcdabcd';
 print join qq(\n), $str =~ /.{8}/g, qq(\n);
 my $alphabet = qr{ abcd }xms;
 print join qq(\n), $str =~ /$alphabet$alphabet/g, qq(\n);
 print join qq(\n), $str =~ /$alphabet{2}/g, qq(\n);
"
abcdabcd
abcdabcd
abcdabcd

abcdabcd
abcdabcd
abcdabcd

abcdabcd
abcdabcd
abcdabcd