How to automatically update tag file in vim?

Question

I use vim C++ tag file for navigation using Ctrl-]. The problem is whenever some file gets modified, the links are no longer valid and I have to re-run ctags and update the tag

Answer 1

This logic works for most cases: When opening a new file in vim, change to the directory of that file and generate a tags file there if it does not already exist. When saving a changed buffer, generate a tags file in the directory of the file being saved:

---

function! GenerateTagsFile()
  if (!filereadable("tags"))
    exec ":!start /min ctags -R --c++-kinds=+p --fields=+iaS --extra=+q --sort=foldcase ."
  endif
endfunction

" Always change to directory of the buffer currently in focus.
autocmd! bufenter *.* :cd %:p:h
autocmd! bufread  *.* :cd %:p:h

" Generate tags on opening an existing file.
autocmd! bufreadpost *.cpp :call GenerateTagsFile()
autocmd! bufreadpost *.c   :call GenerateTagsFile()
autocmd! bufreadpost *.h   :call GenerateTagsFile()

" Generate tags on save. Note that this regenerates tags for all files in current folder.
autocmd! bufwritepost *.cpp :call GenerateTagsFile()
autocmd! bufwritepost *.c   :call GenerateTagsFile()
autocmd! bufwritepost *.h   :call GenerateTagsFile()