Where do filetype-specific autocommands live?

Question

I have a plugin for a specific filetype (*.tex), and I'm wondering where I can find all the commands which are executed when I type :e examplefile.tex? In general, is there a standardized practice for where to keep filetype-specific autocommands within a plugin?

Answer 1

Vim will load filetype-specific commands from an ftplugin. See :help ftplugin.

In short, you can create a file under ~/.vim/ftplugin (or %HOME%\vimfiles\ftplugin on Windows), or better ~/.vim/after/ftplugin (or %HOME%\vimfiles\after\ftplugin) named after the filetype for which it should be loaded.

For example, when a file is detected with filetype=tex, Vim will load files ftpugin/tex.vim, ftplugin/tex_*.vim and ftplugin/tex/*.vim (from both ~/.vim and ~/.vim/after), so you can use a suffix after an _ or a subdirectory if you want to manage multiple separate files with commands.

Usually, it's better to use the ~/.vim/after/ftplugin directory for your user ftplugins, because this directory is loaded last and the commands in it will run after the filetype-specific scripts from $VIMRUNTIME have loaded. Usually, that means you can have the final say on the value of options, if you're loading from ~/.vim/after.

Note that ftplugins are loaded based on the filetype and not the extension of the file! There's a process by which Vim autocmds will define what to set the 'filetype' option to, when opening a file. It usually bases the decision on the file extension (or the whole filename in many cases), but it can often include inspecting the contents of the file itself.

For example, a *.tex file can get 'filetype' set to either tex (which actually means it's a LaTeX file), or plaintex (pure TeX). If you typically edit LaTeX only, you might want to add let g:tex_flavor = "latex" to your vimrc in order to make that the default. See :help ft-tex-plugin for more details on how the auto-detection works.

If you want to add auto-detection for new filetypes, see :help new-filetype. The :help plugin-filetype section also has useful information, you might want to take a peek at that one as well.

Answer 2

A couple of other tips-n-tricks:

• with tpope/scriptease, you can use :Vedit (and other variants) to fill the location list with all runtimepath entries matching the provided file (e.g., :Vedit ftplugin/tex.vim)
• to actually put an autocommand on a specific filetype, such as "automatically run :Require on clojure files when they save," you can use a <buffer>-based autocommand in your ftplugin:

augroup CljRequire
  " can't use autocmd! here because it would clear the group entirely
  autocmd! * <buffer>
  autocmd BufWritePost <buffer> silent! Require
augroup END

and the matching b:undo_ftplugin entry is 'autocmd! CljRequire * <buffer>'.