autocommand BufRead not working in vim when saving an empty buffer

Question

I'm trying to use autocmd to get some filename-specific mappings. I followed some instructions online and write the following thing in my vimrc:

autocmd BufRead,BufNewFile special.txt (some mappings here)

It works fine when I enter a file or create a new buffer with the name special.txt, but not when I create an empty buffer (for example, when starting vim with no argument) and save it with a name special.txt.

Even a simple echomsg won't work:

autocmd BufRead,BufNewFile special.txt echomsg test

and there's no text test in message history.

But in the documentation of BufRead I see

Also triggered for the filetypedetect group when executing ":filetype detect" and when writing an unnamed buffer in a way that the buffer gets a name.

When I save an empty buffer with the name special.txt, the buffer gets a name and BufRead should be triggered. But in fact it is not. Is there anything I'm missing, or I just have to use another autocommand event?

And in case it is useful, I'm using command line version of vim in the vim-gtk package from Ubuntu repository.

Answer 1

You have to interpret the help text like this:

Also triggered [only] for the filetypedetect group when (executing ":filetype detect" [or] when writing an unnamed buffer in a way that the buffer gets a name).

So, this one works:

:autocmd filetypedetect BufRead,BufNewFile special.txt echomsg "ftdetect test"