Vim_create_path.md

Vim will not create parent directories if they do not exist on write.

A common method to ensure the path exists is to use an autocmd to check if the parent path exists and if not create it.

function! MkDir(path) abort
  if !isdirectory(a:path)
    call mkdir(a:path, 'p')
  endif
endfunction

augroup MkDir
  autocmd!
  autocmd BufWritePre * call MkDir(expand('<afile>:p:h'))
augroup END

This is effective but hardly efficient. Every time we write any buffer we check for the existence of the parent path.

Firstly the BufWritePre event can be swapped for the BufNewFile event, the later being triggered far less often. However this means if we open a new file but choose to abandon it (not writing it) we now have inadvertently created a path on disk. Instead of immediately creating the path we want to defer it to when/if the buffer is written. So upon editing a new file check if its parent path exists, if not set up a buffer local one shot autocmd to create the path prior to any attempt to write it.

function! MkDir(path) abort
  if !isdirectory(a:path)
    execute "autocmd MkDir BufWritePre <buffer>"
      \ "call mkdir(" . a:path . ", 'p')"
      \ "| autocmd! MkDir * <buffer>"
  endif
endfunction

augroup MkDir
  autocmd!
  autocmd BufNewFile * call MkDir(expand('<afile>:p:h'))
augroup END

This checks the path once and only creates it (if needed) on write.