Wanrong Lin <wanrong.lin@gmail.com> writes:

> I am trying to customize the org-agenda-file-regexp variable to exclude
> those auto backup files starting with "#", but found out the regexp does
> not have any effect on agend file list. And I further found out it seems
> the variable org-agenda-file-regexp is not used in org.el at all. In
> function "org-agenda-files", the regular expression is hard coded to
> "\\.org\\'", as in these two lines:
>
> (if (file-directory-p f)
>     (directory-files f t "\\.org\\'")
>
> I wonder whether this is a bug and should be fixed. Thank you.

I think this should be fixed.  Here is a patch.