RE: [External] : Re: Regexp for matching control character, say, FORM FEED. (Was: Re: The `^L' appeared in built-in help.)

[Drew Adams <drew.adams@oracle.com>]

> > > M-x insert-char RET form feed (ff) RET
> >
> > aka:
> >
> > `C-q C-l'
> >
> > https://www.gnu.org/software/emacs/manual/html_node/emacs/Inserting-Text.html
> 
> If I don't know the Unicode name and the above input sequence of it,
> to be more specifically, I only know its representation in Emacs is
> ^L, then how to search/match/find/filter out it with regexp.
> 
> As a similar example, I can grep it with the following
> 
> $ grep $'\014' 11.txt | cat -te
> ^L$
> $ grep $'\f' 11.txt | cat -te
> ^L$

It's not clear (to me) what you're trying to do.
The initial question was about _inserting_ the char, I believe.
For that, `C-q' is the easiest way for a control char, since
you can just hit the key for the control char (`C-l' in this case).

For other Unicode chars, `M-x insert-char' can help, but you don't
need that just to insert an ASCII control char.

Now you seem to be asking something else, and what it is is not
clear to me.  If you're asking about search, then just use `C-q':
`C-s C-q C-l'