Modeline magic

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created 2002 · complexity basic · version 6.0

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Options set in your vimrc will apply to all files that you edit. You can also set:

• Different options for all files of a certain type (for example, all *.py files). See filetype.vim and filetypes and an example.
• Different options for a particular file using modelines (this tip).

The modeline cannot be anywhere in the file: it must be in the first or last few lines. The exact location where vim checks for the modeline is controlled by the modelines variable; see :help 'modelines'. By default, it is set to 5 lines.

In a Python file, the '#' starts a comment so the modeline is not interpreted by Python.

The following examples show some alternatives that could be in a C file:

// vim: noai:ts=4:sw=4
   -or-
/* vim: noai:ts=4:sw=4
*/
   -or-
/* vim: set noai ts=4 sw=4: */
   -or-
/* vim: set fdm=expr fde=getline(v\:lnum)=~'{'?'>1'\:'1': */

" Use substitute() instead of printf() to handle '%%s' modeline in LaTeX " files. function! AppendModeline()

 let l:modeline = printf(" vim: set ts=%d sw=%d tw=%d %set :",
       \ &tabstop, &shiftwidth, &textwidth, &expandtab ?  : 'no')
 let l:modeline = substitute(&commentstring, "%s", l:modeline, "")
 call append(line("$"), l:modeline)

endfunction nnoremap <silent> <Leader>ml :call AppendModeline()<CR>

In a C file, you would get a modeline like this:

/* vim: set ts=8 sw=4 tw=0 noet : */

Alternatively, you could use a simple menu entry, for example:

amenu Edit.Insert\ &modeline <C-
Security
 TO DO 

*Need note on security implications of modelines and reference to alternatives.
*Text other than "vim:" can be recognised as a modeline.
*Google "vim modeline vulnerability" (without quotes) for information.

References
*:help auto-setting
*:help modeline
*:help 'modeline' determines whether to look for modelines
*:help 'modelines' number of lines checked to find each modeline

Comments
This mechanism can be extended to 'let' – see script#83.

See script#1876 - securemodelines

How can we make this page more discoverable? New users may have seen a comment at the top of a file, with vim settings in it, but they don't know that this is called a 'modeline'. They may search for something like "set options in a comment" and we should return this page. --Preceding unsigned comment added bIt should help Google find that as well. In practice it is difficult anticipating what people might search for, but your suggested text is very reasonable so a redirect is worthwhile. JohnBeckett (talk) 09:10, November 26, 2013 (UTC)
::I just tried "vim set options in a comment" (without quotes) in Google, and this page was #3, behind Stackoverflow at #1 and #2. It's hard to improve on #3, but we'll see what happens in a few days. JohnBeckett (talk) 09:12, November 26, 2013 (UTC)