Using replace-regexp doesn't remove newlines?

Using replace-regexp doesn't remove newlines?

[ozark]

Some of the lines in the buffer have only the single character '#' in
them. I want to remove all such lines.
I tried doing the following:

M-x replace-regexp ^#$<RET><RET>
This replaces the lines with # in them by blank lines. As this is not I
want, I undid that, and instead tried

M-x replace-regexp ^#$C-qC-j<RET><RET>
This just says "Replaced 0 occurrences" and does nothing. Why is this
so? (I also tried C-m instead of C-j, it doesn't work either. I'm using
Linux)

I was able to achieve what I wanted by first replacing the # lines by
blank lines (the former of the two above), and then removing all blank
lines with
M-x replace-regexp C-qC-jC-qC-j<RET>C-qC-j<RET>
but in general, I may not want to remove all blank lines in the buffer.

So my question is:
a)Why doesn't M-x replace-regexp ^#$C-qC-j<RET><RET> work?
b)What is the regexp I must use to do what I intended?

Thanks,

Re: Using replace-regexp doesn't remove newlines?

[David Kastrup]

"ozark" <shreevatsa@gmail.com> writes:

> Some of the lines in the buffer have only the single character '#' in
> them. I want to remove all such lines.
> I tried doing the following:
>
> M-x replace-regexp ^#$<RET><RET>
> This replaces the lines with # in them by blank lines. As this is not I
> want, I undid that, and instead tried
>
> M-x replace-regexp ^#$C-qC-j<RET><RET>
> This just says "Replaced 0 occurrences" and does nothing. Why is this
> so? (I also tried C-m instead of C-j, it doesn't work either. I'm using
> Linux)

Leave off the $.  It is described in

(info "(emacs)Regexps")

`$'
     is similar to `^' but matches only at the end of a line.  Thus,
     `x+$' matches a string of one `x' or more at the end of a line.

     For historical compatibility reasons, `$' can be used with this
     meaning only at the end of the regular expression, or before `\)'
     or `\|'.

And the C-q C-j is quite enough to match the end of line.

-- 
David Kastrup, Kriemhildstr. 15, 44793 Bochum

Re: Using replace-regexp doesn't remove newlines?

[ozark]

Oh wow, thanks!
And thanks also for that emacs Regexps info page, I'd been looking for
it a long time, but just wasn't able to find it!

Thanks a lot,