[me@fedora ~]$ time sed -e '/^........k.$/!d; /a/!d; /b/!d; /c/!d; /a.*a/d; /b.*b/d; /c.*c/d' /usr/share/dict/words | wc -l 17 real 0m0,075s user 0m0,070

[me@fedora ~]$ time sed -e '/^........k.$/!d; /a/!d; /b/!d; /c/!d; /a.*a/d; /b.*b/d; /c.*c/d' /usr/share/dict/words | wc -l 17 real 0m0,075s user 0m0,070s sys 0m0,006s