Create a custom command and function to create a new file in vim.

command! -nargs=1 Ms call s:NewFile(<q-args>)`

function! s:NewFile(fp)
  echom a:fp
  execute "e " . "~/foo/bar/" . a:fp . ".ext"
endfunction

Useful help:

• :h %:h → filename modifiers
• :h expand() → expand wildcards, including filename modifiers

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