General UNIX puzzle

[Chris Pressey]

On Sat, 17 Jan 2004 14:50:18 -0700
Brett Glass <brett at lariat.org> wrote:

> For example, while I received answers involving languages, such as
> sed and awk, the simplest answer to at least one of them seems to use
> grep.

How so?  My first thought for #3 was 'fgrep -v string', but on
re-reading the problem, I realized that wouldn't quite cut it.
Unless grep has a 'change behaviour after first match' type switch that
I've somehow failed to see in its man page...

-Chris