Re: grep command doc - point out that you can chain now

[David Kastrup]

"Drew Adams" <address@hidden> writes:

> I just found out from Le Wang that you can now chain grep commands within
> the Emacs `grep' command. I mean that you can now do `M-x grep foo *.el |
> grep bar | grep toto'.
>
> This is absolutely wonderful. I don't know when it was added (I suspect
> Emacs 22) - it wasn't available in Emacs 20, in any case. (In Emacs 20, I've
> been using `M-!' to chain greps, or doing it outside Emacs. BTW,
> `flush-lines' doesn't work in *grep*, because it throws off the `next-error'
> index.)
>
> Chaining this way, in my experience, represents how most programmers use
> grep. Instead of trying to come up with a complex regexp, they just use two
> or three chained greps. The technique is so useful that I've applied it to
> the use of regexps generally (e.g. regexp searching) in my own libraries.
>
> So, I'm disappointed to see that this is not pointed out in the Emacs manual
> presentation of `grep'. I really think this is worth pointing out
> explicitly, with a simple example, especially since it was not possible
> before.

Why wouldn't it have been possible before?

-- 
David Kastrup, Kriemhildstr. 15, 44793 Bochum