Writing modified buffer to a temporary file

Question

I'd like to write the modified buffer I'm currently editing to a temporary file periodically. In the background I could then, for example, use external tools to analyze the file.

I don't want to write the file to it real location in this process - I want the user to be in charge of that through the normal :w command.

How can I do this in a vimscript called by the CursorHold autocommand? Vim 7.4 and up is fine.

Answer 1

This is rather simple:

:autocmd CursorHold *
\   let save_modified = &modified |
\       silent! execute 'write' fnameescape(tempname()) |
\   let &modified = save_modified

However, this has the side effect of naming a :new buffer on the first triggering. (It doesn't affect existing files; this is the difference between :write and :saveas.) You can either add another check (empty(bufname(''))) and undo that via :0file, or move to lower-level functions altogether:

:autocmd CursorHold * call writefile(getline(1, '$'), tempname())

The caveat of this approach is that the file contents will always be persisted

• with Vim's 'encoding' setting, i.e. you lose any custom 'fileencoding' of the original buffer, and
• with Unix (LF) line endings (which you could restore with a map() over the list returned by getline()).