How do I yank all matching lines into one buffer?

Question

How do you yank all matching lines into a buffer?

Given a file like:

match 1
skip
skip
match 2
match 3
skip

I want to be able issue a c

Answer 1

Oh I just realized after commenting above that it's easy to yank matching lines into a temporary buffer...

:r !grep "pattern" file.txt

The simplest solutions come once you've given up on finding them. :)