下午五点半是什么时辰

Question

I have au BufRead,BufNewFile *.vm set ft=velocity in vimrc.
But if open .vm file and run :set filetype?, still get filetype=conf.
How to fix this?

Answer 1

First as a general advice, :h :verbose is a good way to debug stuff with Vim:

                        *:verb* *:verbose*
:[count]verb[ose] {command}
            Execute {command} with 'verbose' set to [count].  If
            [count] is omitted one is used. ":0verbose" can be
            used to set 'verbose' to zero.

So using :verbose set ft? in the buffer with the wrong filetype allows you to see what was the last piece of configuration which set the filetype of your buffer. For example I get this result for a typescript source file:

filetype=typescript
        Last set from ~/.dotfiles/vim/plugged/yats.vim/ftdetect/typescript.vim

Secondly the best practice to write your own filetype is to use the ftdetect directory (:h ftdetect). The idea is to create a directory ftdetect in your runtimepath. In it you should create a file name mynewfiletype.vim (here it would be velocity.vim).

In this file you can create an autocommand like the one you put in your vimrc. Note that you should always put the autocommands in your vimrc in an augroup to avoid side effects but the autocommands used in the ftdetect files should not be in an augroup because Vim already does that for you.